THE CLIMATE WEATHER EYE


  
 
Sunset from Western Australia                            Photo: John Maunder 
 
 
 "The Sun pays no heed to human committees"

*This phrase with a minor change is given in a NASA release on "New Solar Cycle Prediction" on May 29 2009 (see http://science.nasa.gov/headlines/y2009/29may_noaaprediction.htm 

Last Update October 16, 2017 

The Weekend Sun newspaper is published every Friday in Tauranga ( New Zealand) and contains a range of local information including comments from several columnists. During part of 2012, I provided a "Weather Eye" comment which was published on the second and fourth Friday of each month. My column was also published  on the website SunLive  which attracts over 200,000 weekly visitors. 

 
From  March 2013 my column is continuing and is now published each week on Sunlive.

****************************************************

The latest  WeatherEye No 232 i ssued on  October  16 , 2017


Tropospheric Temperatures 1992 to September 2017

Weather Eye
with John Maunder

The chart below shows that since 1979, when reliable satellite observations became available, there has been little overall trend in the average tropospheric temperatures, apart from  milder/warmer temperatures since about 1997, and two significant warm periods associated with the El Nino events in 1998 and 2015-16

 

 

 

 The latest global average temperatures of the troposphere updated to September 2017– observed from US National Oceanic and Atmospheric Administration satellites – are computed by the University of Alabama at Huntsville in the United States. The data shows variations from the 30 year period 1981-2010.

Since 1979, NOAA satellites have been carrying instruments which measure the natural microwave thermal emissions from oxygen in the atmosphere. The intensity of the signals these microwave radiometers measure at different microwave frequencies is directly proportional to the temperature of different, deep layers of the atmosphere. Every month, researchers at the University of Alabama   (Dr John Christy and  Dr Roy Spencer) update global temperature datasets that represent the piecing together of the temperature data from a total of fourteen instruments flying on different satellites over the years.

The graph above represents the latest update; updates are usually made within the first week of every month. Contrary to some reports, the satellite measurements are not calibrated in any way with the global surface-based thermometer records of temperature. They instead use their own on-board precision redundant platinum resistance thermometers calibrated to a laboratory reference standard before launch.

The troposphere is the lowest layer of Earth's atmosphere.

It contains approximately 75 per cent of the atmosphere's mass and 99 per cent of its water vapour and aerosols.

The average depth of the troposphere is approximately 17 km in the middle latitudes.

The tropospheric temperature data for 2011 is January 0.0 degrees Celsius, February -0.02, March -0.10, April +0.12, May +0.14, June +0.32, July +0.38, August +0.33, September +0.29, October +0.12, November +0.12, December +0.10 degrees.

The data for 2012 is: January -0.09 degrees, February -0.12, March +0.11, April +0.29, May +0.29, June +0.37, July +0.28, August +0.34, November +0.28, December +0.20 degrees.

The data for 2013 is: January +0.50 degrees, February +0.18, March +0.20, April +0.10, May +0.07, June +0.30, July +0.17, August +0,16, September +0.37, October +0.29, November +0.19, December +0.23 degrees.

The data for 2014 is: January +0.30 degrees, February +0.18, March +0.17, April +0.19, May +0.33, June +0.31, July +0.30, August +0.20, September +0.30, October +0.37, November +0.33, and December +0.33 degrees Celsius.

The data for 2015 is: January +0.20 degrees C, February +0.18 degrees C, March +0.14 degrees C, April +0.07 degrees C, May +0.30 degrees C, June +0.32 degrees C, July +0.18 degrees C, August +0.22 degrees C, September +0.20 degrees C, October +0.32 degrees C, November +0.40 degrees C, and December +0.48 degrees C.

The data for 2016 is: January +0.55 degrees C,  February +0.83 degrees C, March  +0.73 degrees C, April +0.71 degrees C, May +0.55  degrees, June +0.33 degrees C, July +0.39 degrees C, August +0.38 degrees C, September  +0.44 degrees C, October +0.35 degrees, November +0.40 degrees C, and December +0.24 degrees C.

The data for 2017 is: January +0.31 degrees C, February +0.35 degrees C, March +0.37 degrees C,  April +0.40 degrees C ,  May  +0.47 degrees C , June  +0.21 degrees C, July +0.28 degrees C, August +0.41 degrees C, and September +0.54 degrees C.   

The coolest months since 1979 were September 1984, with minus 0.49 degrees Celsius, and November 1984, with minus 0.42 degrees Celsius.

The warmest months were February 2016 with plus 0.83 degrees C, February and April 1998, both plus 0.76 degrees Celsius, and March 2016 plus 0.73 degrees, and April 2016 plus 0.73 degrees Celsius.

The chart shows the El Nino warming in the 1998 period, and 2015-16, and the Mount Pinatubo, volcanic cooling during 1992-1993.


Tauranga September Average Afternoon Temperatures 1913-2017

Weather Eye
with John Maunder

Temperatures have been recorded in the Tauranga area at several sites in the last 100 years, including the current Tauranga Airport site from June 1990.

 

 The graph shows details of the average daily maximum temperatures (simply called “afternoon”) for Tauranga for September from 1913-2017.

The long-term average afternoon temperature in September for Tauranga is 16.6 degrees C, ranging from the “cool” September months of 1964 (14.8 degrees C), and 1977 (14.9 degrees C), to the “warm” September months of 1915 (18.4 degrees C), and 18.3 degrees in 1914.

The afternoon temperature for 2015 was 16.1 degrees C, which made it the coolest September for 11 years.

In contrast, September 2017 had an average afternoon temperature of   16.8 degrees C, which was close to normal.

The graph of the average afternoon temperatures for September shows generally "normal" variations from September to September during the last 100 years, but five of the warmest six September months occurred from 1913 to 1921.

From 1913 to 2017, there have been ten September months with an average afternoon temperature of 17.5 degrees C or more, and eight September months with an average afternoon temperature of less than 15.4 degrees C.

The tenth “warmest” September months (in terms of afternoon temperatures) on record, in chronological order, are 1913, 1914, 1915, 1916, 1921, 1926, 1940, 2006, 2009 and 2014.

By contrast, the eighth “coolest” September months (in terms of afternoon temperatures) on record, in chronological order, are 1935, 1964, 1967, 1977, 1992, 1993, 1994 and 1997.

The average afternoon temperature during September for the period 1914-62 was 16.6 degrees, compared with 16.5 degrees from 1963-2011



Tauranga September Rainfalls 1898-2017

Weather Eye
with John Maunder

Rainfalls for the month of September have been recorded in Tauranga since 1898, except for 1904, 1907, 1908, and 1909.

The graph below shows the range of rainfalls from an extreme high of 274 mm in 1973 to a low of only 16 mm in 1965.

 

 

The second wettest September was in 1900, when 256 mm was recorded, and the second driest September was in 1944, when only 27 mm fell. The long-term average rainfall for Tauranga for September is 105 mm.

The graph of the September rainfall shows normal variations from year to year. Since 1898, there have been five Septembers with a rainfall of 200 mm or more (four of which occurred during the period 1900 to 1928, but there's only been one since then), compared with six September months with a rainfalls of 40 mm or less.

The rainfall for September 2016 was 166 mm, and the rainfall in September 2017 was 185 mm,  was the tenth wettest September on record, and the wettest since 1973.

In chronological order, the ten wettest September months (rainfalls over 180 mm) are 1900,1912,1919,1923,1928,1946,1960,1969,1971,1973, and 2017.

In contrast the eleven driest September months (rainfalls of 50 mm or less) are 1910, 1913, 1914, 1921, 1922, 1944, 1965, 1993, 1987, 2006 and 2011.

The average rainfall for Tauranga for September for the 50 years 1961-2010 of 103 mm is similar to the rainfall for the previous 50 years (1910-1960).

For further information on a range of weather/climate matters see https://sites.google.com/site/climatediceandthebutterfly/

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The Southern Oscillation Index

Weather Eye
with John Maunder

 

The Southern Oscillation Index (SOI) is a standardized index based on the observed sea level pressure differences between Tahiti and Darwin, Australia.

The SOI is a leading measure of the large-scale fluctuations in air pressure occurring between the western and eastern tropical Pacific (i.e., the state of the Southern Oscillation) during El Niño and La Niña episodes.

In general, smoothed time series of the SOI correspond very well with changes in ocean temperatures across the eastern tropical Pacific. 

The negative phase of the SOI represents below-normal air pressure at Tahiti and above-normal air pressure at Darwin. 

The positive phase of the SOI represents above-normal air pressure at Tahiti and below-normal air pressure at Darwin. 

Prolonged periods of negative SOI values coincide with abnormally warm  ocean waters across the eastern tropical Pacific typical of El Niño episodes. 

In contrast, prolonged periods of positive SOI values coincide with abnormally cold ocean waters across the eastern tropical Pacific typical of La Niña episodes. 

Sustained negative values of the SOI below −8 often indicate El Niño episodes.

These negative values are usually accompanied by sustained warming of the central and eastern tropical Pacific Ocean, a decrease in the strength of the Pacific Trade Winds.

Sustained positive values of the SOI above +8 are typical of a La Niña episode.

They are associated with stronger Pacific trade winds and warmer sea temperatures to the north of Australia. Waters in the central and eastern tropical Pacific Ocean become cooler during this time.

The El Niño—Southern Oscillation (ENSO) is currently neutral. All international climate models surveyed by the Australian Bureau of Meteorology suggest the tropical Pacific Ocean is likely to stay ENSO neutral for the remainder of 2017.

Sea surface temperatures (SSTs) have cooled over much of the central tropical Pacific during the past four weeks, and are now close to the long-term average, and within the neutral range. The 30-day Southern Oscillation Index (SOI) also remains neutral, having steadied over the past three weeks. Other indicators of ENSO, such as cloudiness near the Date Line and trade winds are also at neutral levels.

The graph below ( from the Bureau of Meteorology in Australia) shows monthly values of the SOI in recent years updated to mid September 2017. 

The tropical Pacific Ocean is currently neutral. Most climate models indicate the Pacific is likely to remain ENSO neutral for the remainder of 2017. This means the Bureau's ENSO Outlook is currently “inactive”, with neither El Niño nor La Niña expected to influence Australia's climate this year.

Although the tropical Pacific Ocean is slightly warmer than usual, this warmth is within the ENSO neutral range. The Southern Oscillation Index (SOI) has recently been negative due to higher than normal atmospheric pressure in the Australian region, but all other ENSO indicators are at neutral levels.

 

 

 

Most atmospheric and oceanic indicators of ENSO are currently neutral. However, sea surface temperatures (SSTs) in the eastern Pacific Ocean have warmed since the start of the year, and the Southern Oscillation Index (SOI) has been trending downwards. While these are fairly typical changes in the lead up to El Niño, trade winds and cloudiness have not shown any significant shift away from neutral.

El Nino and La Nina weather affects over New Zealand (source Niwa)

During El Niño, New Zealand tends to experience stronger or more frequent winds from the west in summer, typically leading to drought in east coast areas and more rain in the west.

In winter, the winds tend to be more from the south, bringing colder conditions to both the land and the surrounding ocean.

In spring and autumn south–westerly winds are more common.

La Niña events have different impacts on New Zealand's climate. More north–easterly winds are characteristic, which tend to bring moist, rainy conditions to the north–east of the North Island, and reduced rainfall to the south and south–west of the South Island.

Therefore, some areas, such as central Otago and South Canterbury, can experience drought in both El Niño and La Niña.

Warmer than normal temperatures typically occur over much of the country during La Niña, although there are regional and seasonal exceptions.

Although ENSO events have an important influence on New Zealand's climate, it accounts for less than 25 per cent of the year to year variance in seasonal rainfall and temperature at most New Zealand measurement sites.

For further information on  a range of weather and climate matters see: https://sites.google.com/site/climatediceandthebutterfly/




Tropospheric Temperatures 1979 to August 2017

Weather Eye
with John Maunder

The chart below shows that since 1979, when reliable satellite observations became available, there has been little overall trend in the average tropospheric temperatures, apart from  milder/warmer temperatures since about 1997, and two significant warm periods associated with the El Nino events in 1998 and 2015-16.

The latest global average temperatures of the troposphere updated to June 2017– observed from US National Oceanic and Atmospheric Administration satellites – are computed by the University of Alabama at Huntsville in the United States. The data shows variations from the 30 year period 1981-2010.

Since 1979, NOAA satellites have been carrying instruments which measure the natural microwave thermal emissions from oxygen in the atmosphere. The intensity of the signals these microwave radiometers measure at different microwave frequencies is directly proportional to the temperature of different, deep layers of the atmosphere. Every month, researchers at the University of Alabama   (Dr John Christy and  Dr Roy Spencer) update global temperature datasets that represent the piecing together of the temperature data from a total of fourteen instruments flying on different satellites over the years.

The graph above represents the latest update; updates are usually made within the first week of every month. Contrary to some reports, the satellite measurements are not calibrated in any way with the global surface-based thermometer records of temperature. They instead use their own on-board precision redundant platinum resistance thermometers calibrated to a laboratory reference standard before launch.

The troposphere is the lowest layer of Earth's atmosphere.

It contains approximately 75 per cent of the atmosphere's mass and 99 per cent of its water vapour and aerosols.

The average depth of the troposphere is approximately 17 km in the middle latitudes.

The tropospheric temperature data for 2011 is January 0.0 degrees Celsius, February -0.02, March -0.10, April +0.12, May +0.14, June +0.32, July +0.38, August +0.33, September +0.29, October +0.12, November +0.12, December +0.10 degrees.

The data for 2012 is: January -0.09 degrees, February -0.12, March +0.11, April +0.29, May +0.29, June +0.37, July +0.28, August +0.34, November +0.28, December +0.20 degrees.

The data for 2013 is: January +0.50 degrees, February +0.18, March +0.20, April +0.10, May +0.07, June +0.30, July +0.17, August +0,16, September +0.37, October +0.29, November +0.19, December +0.23 degrees.

The data for 2014 is: January +0.30 degrees, February +0.18, March +0.17, April +0.19, May +0.33, June +0.31, July +0.30, August +0.20, September +0.30, October +0.37, November +0.33, and December +0.33 degrees Celsius.

The data for 2015 is: January +0.20 degrees C, February +0.18 degrees C, March +0.14 degrees C, April +0.07 degrees C, May +0.30 degrees C, June +0.32 degrees C, July +0.18 degrees C, August +0.22 degrees C, September +0.20 degrees C, October +0.32 degrees C, November +0.40 degrees C, and December +0.48 degrees C.

The data for 2016 is: January +0.55 degrees C,  February +0.83 degrees C, March  +0.73 degrees C, April +0.71 degrees C, May +0.55  degrees, June +0.33 degrees C, July +0.39 degrees C, August +0.38 degrees C, September  +0.44 degrees C, October +0.35 degrees, November +0.40 degrees C, and December +0.24 degrees C.

The data for 2017 is: January +0.31 degrees C, February +0.35 degrees C, March +0.37 degrees C,  April +0.40 degrees C ,  May  +0.47 degrees C , June  +0.21 degrees C, July +0.28 degrees C, and August +0.41 degrees C.    

The coolest months since 1979 were September 1984, with minus 0.49 degrees Celsius, and November 1984, with minus 0.42 degrees Celsius.

The warmest months were February 2016 with plus 0.83 degrees C, February and April 1998, both plus 0.76 degrees Celsius, and March 2016 plus 0.73 degrees, and April 2016 plus 0.73 degrees Celsius.

The chart shows the El Nino warming in the 1998 period, and 2015-16, and the Mount Pinatubo, volcanic cooling during 1992-1993.

Details: http://www.drroyspencer.com/latest-global-temperatures/

For further information see: https://sites.google.com/site/climatediceandthebutterfly/





Tauranga August Average Afternoon Temperatures 1913-2017

Weather Eye
with John Maunder

 

Temperatures have been recorded in the Tauranga area at several sites in the last 100 years, including the current Tauranga Airport site from June 1990.

The graph shows details of the average daily maximum temperatures, called simply ‘afternoon' for Tauranga for August from 1913-2015. The average for August 2017 was 16.0 degrees Celsius which made August 2107 as the fourth equal mildest August on record.

 

The long-term average afternoon temperature in August for Tauranga is 14.8 degrees Celsius. The coolest August months have been 1932 with 13.8 degrees Celsius, and 1941 and 1992 recording 13.9 degrees Celsius.

The warm August months have been 2013 with 16.7 degrees Celsius, 1915 with 16.4 degrees Celsius, 2009 had 16.2 degrees Celsius, and 2017 with 16.0 degrees Celsius.

The graph of the average afternoon temperatures for August shows generally normal variations from August to August during the last 100 years.

But several recent August months have been a little warmer than others since 1913.  This includes August 2013, the warmest on record with a temperature of 16.7 degrees Celsius, which was 1.9 degrees Celsius above average.

In comparison, the value for August 2016 was 15.1 degrees Celsius, which made it 1.6 degrees Celsius colder than August 2013.

From 1913 to 2017, there have been 11 August months with an average afternoon temperature of 15.8 degrees Celsius or more.

Thirteen August months have had an average afternoon temperature of less than 14.3 degrees Celsius.

The seventh warmest August months – in terms of afternoon temperatures – on record in chronological order are: 1915, 1967, 1971, 2009, 2012, 2013, and 2017. By contrast, the fifth coolest August months – in terms of afternoon temperatures – on record, in chronological order are: 1932, 1941, 1966, 1992 and 2004.

The average afternoon temperatures during August for the period 1914-1963 were 14.7 degrees Celsius, compared with 15.0 degrees Celsius from 1964 to 2013.

For further information on a range of weather/climate matters see: https://sites.google.com/site/climatediceandthebutterfly/




Tauranga Rainfalls August 1898-2017

Weather Eye
with John Maunder

Rainfalls for the month of August have been recorded in Tauranga since 1898, except for 1904, 1907, 1908 and 1909.

From January 1898 to December 1904, the observation site was described as the Tauranga Harbour, from November 1904 to April 1907 the site was described as simply ‘Tauranga'. From January 1910 to December 1923 the site was Waikareao, in Otumoetai; from January 1924 to September 1940 the site was at 148 Waihi Rd, in Judea; from October 1940 to January 1941 the site was at Te Puna; and from February 1941 to now, the site is Tauranga Airport.

The methodology use in adjusting the older sites to the current observing site is published in the ‘NZ Meteorological Service Miscellaneous Publication' No 180 in 1984.

It is considered that the homogeneous rainfall series described here is a fair and true record of what the rainfall would have been if the current observation site (Tauranga Airport) had been used since 1898.

This should be coupled with the understanding that although standard accepted methodologies have been used, any adjustments are only estimates of what would have occurred if the location of the rainfall records had always been in the same place with the same surroundings and the same or similar recording gauge.

In terms of climate change (such as is it getting wetter or drier, or warmer or colder), the methodology used in computing an ‘official' set of climate observations is very important, as otherwise erroneous conclusions may be drawn.

 

 

The graph shows the range of rainfalls from an extreme high of 274 mm in 2010 to a low of only 17 mm in 1914.

The second wettest August was 1916 when 263 mm was recorded, and the second driest August was in 1982 when only 31 mm fell.

The long-term average rainfall for Tauranga for August is 124 mm. The rainfall for Tauranga for August  2017 was  159 mm.

The graph of the August rainfall shows normal variations from year-to-year.

There is a small decrease in the overall August rainfalls during the last 50 years – from 1961-2010 – from an average of 121 mm, compared with an average of 133 mm during the 50 years from 1911-1960. Since 1898, there have been 11 August months with a rainfall of 220 mm or more – with 10 occurring during 1900 to 1976 – and only one August month since then 2010, which was the highest rainfall for any August. Only five August months have had rainfalls of 50 mm or less.

Chronologically, the 11 wettest August months are 1913, 1916, 1920, 1927, 1938, 1942, 1957, 1965, 1970, 1976 and 2010.

In contrast, chronologically the five driest August months are 1914, 1921, 1982, 1983 and 2002.

For further information on a range of weather/climate matters see :  https://sites.google.com/site/climatediceandthebutterfly/





Sunspots and the Maunder Minimum

Weather Eye
with John Maunder

The ‘Maunder Minimum' is the name given to the period from 1645 to 1715 when the number of sunspots – ‘storms' on the sun – became almost zero.

The period is named after the solar astronomer Edward Walter Maunder (1851-1928), who was working at The Royal Observatory at Greenwich when he discovered the dearth of sunspots during this period.

During one 30-year period within the Maunder Minimum there were only about 50 sunspots compared with a more typical 40,000.

Maunder was a driving force in the foundation of the British Astronomical Association and a fellow of the Royal Astronomical Society.

The sun was well observed during the period of the Maunder Minimum and this lack of sunspots is well documented.

 

This period of solar inactivity corresponded to a climatic period called the ‘Little Ice Age' when in Europe rivers that were normally ice-free, froze and snow fields remained at low altitudes throughout the year.

There is evidence the sun had similar periods of inactivity during the years 1100-1250 and 1460-1550.

Sunspots generally follow a cycle of about 11 years, but cycles have varied from eight-15 years.

The connection between solar activity and the earth's climate is an area of ongoing and sometimes controversial research.

 

Time will tell whether the sun will once again go into another ‘Maunder Minimum' within the lifetime of the present generation, but if this happens we're likely have a much colder climate for a few decades.

 

A sunspot is a relatively dark, sharply defined region on the solar disc – marked by an umbra, dark area, which is 2000 degrees cooler than the effective photospheric temperature.

The average diameter of a sunspot is 4000 km, but they can exceed 200,000 km.

The NASA solar physics website, and other websites such as the Royal Observatory of Belgium, include information on sunspot numbers, the ‘Maunder Minimum' and sunspot cycle predictions.

The sunspot index is updated monthly and available from 1749. The last time the monthly sunspot number was above 100 during the last 14 years was in September 2002, when the value was 110. February 2014 had a sunspot value of 102.

The last time the value was above 200 was in August 1990, when the value was 200.3 – and there were no sunspots observed in September 2009. The value for  sunspots on August 27 was 35. Since January 2017, 24% of the days of the year have been “spotless”. (days without sunspots).

 

For further information see: https://sites.google.com/site/climatediceandthebutterfly/




Tropospheric Temperatures 1979 to July 2017

Weather Eye
with John Maunder

 

The chart below shows that since 1979, when reliable satellite observations became available, there has been little overall trend in the average tropospheric temperatures, apart from a period of somewhat milder temperatures since about 1997, and two significant warm periods associated with the El Nino events in 1998 and 2015-16.

 

 


The latest global average temperatures of the troposphere updated to June 2017– observed from US National Oceanic and Atmospheric Administration satellites – are computed by the University of Alabama at Huntsville in the United States. The data shows variations from the 30 year period 1981-2010.

Since 1979, NOAA satellites have been carrying instruments which measure the natural microwave thermal emissions from oxygen in the atmosphere. The intensity of the signals these microwave radiometers measure at different microwave frequencies is directly proportional to the temperature of different, deep layers of the atmosphere. Every month, researchers at the University of Alabama   (Dr John Christy and  Dr Roy Spencer) update global temperature datasets that represent the piecing together of the temperature data from a total of fourteen instruments flying on different satellites over the years.

The graph above represents the latest update; updates are usually made within the first week of every month. Contrary to some reports, the satellite measurements are not calibrated in any way with the global surface-based thermometer records of temperature. They instead use their own on-board precision redundant platinum resistance thermometers calibrated to a laboratory reference standard before launch.

The troposphere is the lowest layer of Earth's atmosphere.

It contains approximately 75 per cent of the atmosphere's mass and 99 per cent of its water vapour and aerosols.

The average depth of the troposphere is approximately 17 km in the middle latitudes.

The tropospheric temperature data for 2011 is January 0.0 degrees Celsius, February -0.02, March -0.10, April +0.12, May +0.14, June +0.32, July +0.38, August +0.33, September +0.29, October +0.12, November +0.12, December +0.10 degrees.

The data for 2012 is: January -0.09 degrees, February -0.12, March +0.11, April +0.29, May +0.29, June +0.37, July +0.28, August +0.34, November +0.28, December +0.20 degrees.

The data for 2013 is: January +0.50 degrees, February +0.18, March +0.20, April +0.10, May +0.07, June +0.30, July +0.17, August +0,16, September +0.37, October +0.29, November +0.19, December +0.23 degrees.

The data for 2014 is: January +0.30 degrees, February +0.18, March +0.17, April +0.19, May +0.33, June +0.31, July +0.30, August +0.20, September +0.30, October +0.37, November +0.33, and December +0.33 degrees Celsius.

The data for 2015 is: January +0.20 degrees C, February +0.18 degrees C, March +0.14 degrees C, April +0.07 degrees C, May +0.30 degrees C, June +0.32 degrees C, July +0.18 degrees C, August +0.22 degrees C, September +0.20 degrees C, October +0.32 degrees C, November +0.40 degrees C, and December +0.48 degrees C.

The data for 2016 is: January +0.55 degrees C,  February +0.83 degrees C, March  +0.73 degrees C, April +0.71 degrees C, May +0.55  degrees, June +0.33 degrees C, July +0.39 degrees C, August +0.38 degrees C, September  +0.44 degrees C, October +0.35 degrees, November +0.40 degrees C, and December +0.24 degrees C.

The data for 2017 is: January +0.31 degrees C, February +0.35 degrees C, March +0.37 degrees C,  April +0.40 degrees C ,  May  +0.47 degrees C , June  +0.21 degrees C, and July +0.28 degrees C.     

The coolest months since 1979 were September 1984, with minus 0.49 degrees Celsius, and November 1984, with minus 0.42 degrees Celsius.

The warmest months were February 2016 with plus 0.83 degrees C, February and April 1998, both plus 0.76 degrees Celsius, and March 2016 plus 0.73 degrees, and April 2016 plus 0.73 degrees Celsius.

The chart shows the El Nino warming in the 1998 period, and 2015-16, and the Mount Pinatubo, volcanic cooling during 1992-1993.

Details: http://www.drroyspencer.com/latest-global-temperatures/

For further information see:  https://sites.google.com/site/climatediceandthebutterfly/



Tauranga July Average Daily Maximum Temperatures 1913-2017

Weather Eye
with John Maunder

The graph below shows details of the average daily maximum temperatures, called ‘afternoon', for Tauranga for July from 1913-2017.

The temperature for July 2017 was 14.4 degrees Celsius, which was the second coolest July since July 2004.

 

 

It's very common for areas such as Tauranga to have had different observation sites during the years, and readings from the earlier sites have been adjusted to the present site using standard climatologically procedures.

The temperature series described here is a record of what the temperature would have been if the current observation site, Tauranga Airport, had been used throughout the period.

It's important to note, in considering climate change, the methodology used in computing an official set of climate observations is very important as otherwise erroneous conclusions may be drawn.

Traditionally, temperature observations have been recorded with a set of maximum and minimum temperature thermometers.

These record the daily maximum temperature, usually recorded in mid-afternoon, and daily minimum temperature, usually recorded just before dawn.

This analysis of temperatures for Tauranga is for the average daily maximum temperatures.

The long-term average afternoon temperature in July for Tauranga is 14.1 degrees Celsius, ranging from cool July months of 1918 and 1939, both 12.3 degrees Celsius, and 1965, with 12.9 degrees Celsius.

Warm July months include 1916 and 2010, both 15.8 degrees Celsius, and 1915 with 15.7 degrees Celsius.

The graph of the average afternoon temperatures for July shows generally normal variations from July to July in the last 100 years.

But several July months since 1997 have been a little warmer than many of the July months since 1913.

From 1913 to 2017, there have been 10 July months with an average afternoon temperature of 15 degrees Celsius or more, and 11 July months with an average afternoon temperature of less than 13.3 degrees Celsius.

The 11 mildest July months for afternoon temperatures on record, in chronological order are: 1915, 1916, 1917, 1984, 1985, 1998, 2000, 2011, 2012, 2014, and 2016.

By contrast, the seven coolest July months for afternoon temperatures on record, in chronological order are: 1918, 1929, 1935, 1939, 1963, 1965, and 1969.

The average afternoon temperature for Tauranga for July for the 50 years from 1914-1963 was 14.0 degrees Celsius, compared with the average afternoon temperature for Tauranga for July for the 50 years from 1964-2013 was 14.3 degrees Celsius.

For further information see:  https://sites.google.com/site/climatediceandthebutterfly/





Tauranga July Rainfalls 1898-2017

Weather Eye
with John Maunder

Rainfalls for the month of July have been recorded in Tauranga since 1898, except for 1904, 1907, 1908, and 1909.

The graph for the period 1898-2017 shows the range of rainfalls from an extreme high of 348 mm in 1951, to a low of only 2 mm in 1902.

The rainfall for July 2017 was 124 mm. The graph shows the second wettest July was 2012 when 328 mm was recorded, and the second driest July was in 1983 when only 22 mm fell.

 

The long-term average rainfall for Tauranga for July is 129 mm. The graph of the July rainfall shows ‘normal' variations from year to year.

There is a very small decrease in the overall July rainfalls during the last 50 years (1961-2010) from an average of 127 mm, compared with an average of 132 mm during the 50 years from 1911-1960.

Since 1898, there have been 13 July months with a rainfall of 200 mm or more, but only four July months with rainfalls of 40 mm or less.

The ten wettest July months (in chronological order) have been 1905, 1927, 1938, 1951,1963,1979,1988, 2007, 2008, and 2012. The ten driest July months ( in chronological order) have been 1902, 1918, 1922, 1949, 1969, 1975, 1983, 1997, 2001, and 2010,

For further information on a variety of weather and climate matters see 

https://sites.google.com/site/theweatherclimateeye/

https://sites.google.com/site/nzrainfalls/newzealandmonthlyrainfalls



Arctic and Antarctic Temperatures ..... January 2000 to May 2017

Weather Eye
with John Maunder

Each month Professor Ole Humlum of the The University Centre in Svalbard (UNIS), in Norway publishes on the web his very comprehensive web site updating a large number of charts and related analyses of data from international sources such as NASA.

His latest page can be found at: 

http://www.climate4you.com/Text/Climate4you_June_2017.pdf 

Alternatively, you can use the June 2017‘update' link on www.climate4you.com 

One example of what is contained in his web base is a chart of Arctic and Antarctic surface air temperatures from January 200 to May 2017. 

HadCRUT4 is a global temperature dataset, providing gridded temperature anomalies across the world as well as averages for the hemispheres and the globe as a whole. CRUTEM4 and HadSST3 are the land and ocean components of this overall dataset, respectively.

These datasets have been developed by the Climatic Research Unit (University of East Anglia) in conjunction with the Hadley Centre (UK Met Office), apart from the sea surface temperature (SST) dataset which was developed solely by the Hadley Centre. 

Diagram showing area weighted Arctic (70-90 degrees N) monthly surface air temperature anomalies (HadCRUT4) since January 2000, in relation to the WMO normal period 1961-1990. The thin line shows the monthly temperature anomaly, while the thicker line shows the running 37-month (c. 3 year) average.

Diagram showing area weighted Antarctic (70-90 N) monthly surface air temperature anomalies (HadCRUT4) since January 2000, in relation to the WMO normal period 1961-1990.

The thin line shows the monthly temperature anomaly, while the thicker line shows the running 37-month (c. 3 year) average.

For further information on a range of weather/climate matters see: https://sites.google.com/site/climatediceandthebutterfly/

 





Global Monthly Temperatures from NASA ... 1996-June 2017

Weather Eye
with John Maunder

Global temperatures are compiled for various areas including global (land-ocean), global (meteorological stations), three latitude bands, and hemispheric, by the Goddard Institute for Space Studies of NASA.

The graph shows the monthly mean global surface temperature anomaly from the base period 1951-1980, for the period 1996- June 2017. The black line shows meteorological stations only; the dotted line is the land-ocean temperature index obtained from satellite measurements.

For details see https://data.giss.nasa.gov/gistemp/ ( see graphs at the top right hand corner of the front web page and go to months)

The GISS Surface Temperature Analysis (GISTEMP) is an estimate of global surface temperature change. Graphs and tables are updated around the middle of every month using current data files from NOAA GHCN v3 (meteorological stations), ERSST v4 (ocean areas), and SCAR (Antarctic stations), combined as described in our December 2010 publication (Hansen et al. 2010). These updated files incorporate reports for the previous month and also late reports and corrections for earlier month

The basic GISS temperature analysis scheme was defined in the late 1970's by James Hansen when a method of estimating global temperature change was needed for comparison with one-dimensional global climate models. The scheme was based on the finding that the correlation of temperature change was reasonably strong for stations separated by up to 1200 km, especially at middle and high latitudes. This fact proved sufficient to obtain useful estimates for global mean temperature changes. 

 

The chart above shows that from 1995 to mid 2015,  there was a small warming in the global monthly temperatures, and a relatively warm period associated with the recent 2015-2017 El Nino events. 

For further information on a variety of weather and climate matters see: https://sites.google.com/site/climatediceandthebutterfly/





Tauranga Average Afternoon Temperatures June 1914-2017

Weather Eye
with John Maunder

Temperatures have been recorded in the Tauranga area at several sites during the last 100 years, including at the current Tauranga Airport site from June 1990.

The graph shows details of the average daily maximum temperatures, called simply ‘afternoon', for Tauranga for June from 1913-2017.

The long-term average afternoon temperature in June for Tauranga is 14.7 degrees Celsius.

The ‘cool' June months were in 1972 with 13.0 degrees Celsius, 1936 with 13.2 degrees Celsius, and 1933 with 13.3 degrees Celsius.

The ‘warm' June months include 2014 with 16.9 degrees Celsius, 1916 and 2011, both with 16.6 degrees Celsius, and June 2016 with 16.5 degrees Celsius.

June 2014 had an average afternoon temperature of 16.9 degrees Celsius and the warmest June on record since observations were first made in 1913. June 2016 had an average afternoon temperatures of 16.5 degrees C, and this year June had an average afternoon temperature of 16.1 degrees Celsius. This compares with an average afternoon temperature in June 2015 of 15.4 degrees Celsius.

The graph of the average afternoon temperatures for June shows generally ‘normal' variations from June to June during the last 100 years.

But many of the last 20 June months since 1996 have been a little ‘warmer' than other June months since 1913.

From 1913 to 2017, there have been 16 June months with an average afternoon temperature of 15.6 degrees Celsius or more, and 12 June months with an average afternoon temperature of less than 13.9 degrees Celsius.

The 10 ‘warmest' June months on record, in chronological order, are: 1916, 1971, 1981, 1998, 1999, 2002, 2003, 2011, 2014, 2016, and 2016.

By contrast, the seventh ‘coolest' June months on record, in chronological order, are 1933, 1936, 1941, 1944, 1969, 1972 and 1976.

The average afternoon temperature in June during the 50 year period 1914-1963 was 14.7 degrees Celsius compared with 14.8 degrees Celsius for the 50 year period from 1964 to 2013.

For further information on range of weather/climate matters see: https://sites.google.com/site/climatediceandthebutterfly/

For further information contact John Maunder at climate@ihug.co.nz.



Latest Global Average Tropospheric Temperatures 1979 to June 2017

Weather Eye
with John Maunder

The chart below shows that since 1979, when reliable satellite observations became available, there has been little overall trend in the average tropospheric temperatures, apart from a period of somewhat milder temperatures since about 1997, and two significant warm periods associated with the El Nino events in 1998 and 2015-16.

 

The latest global average temperatures of the troposphere updated to June 2017– observed from US National Oceanic and Atmospheric Administration satellites – are computed by the University of Alabama at Huntsville in the United States. The data shows variations from the 30 year period 1981-2010.

Since 1979, NOAA satellites have been carrying instruments which measure the natural microwave thermal emissions from oxygen in the atmosphere. The intensity of the signals these microwave radiometers measure at different microwave frequencies is directly proportional to the temperature of different, deep layers of the atmosphere. Every month, researchers at the University of Alabama   (Dr John Christy and  Dr Roy Spencer) update global temperature datasets that represent the piecing together of the temperature data from a total of fourteen instruments flying on different satellites over the years.

The graph above represents the latest update; updates are usually made within the first week of every month. Contrary to some reports, the satellite measurements are not calibrated in any way with the global surface-based thermometer records of temperature. They instead use their own on-board precision redundant platinum resistance thermometers calibrated to a laboratory reference standard before launch.

The troposphere is the lowest layer of Earth's atmosphere.

It contains approximately 75 per cent of the atmosphere's mass and 99 per cent of its water vapour and aerosols.

The average depth of the troposphere is approximately 17 km in the middle latitudes.

The tropospheric temperature data for 2011 is January 0.0 degrees Celsius, February -0.02, March -0.10, April +0.12, May +0.14, June +0.32, July +0.38, August +0.33, September +0.29, October +0.12, November +0.12, December +0.10 degrees.

The data for 2012 is: January -0.09 degrees, February -0.12, March +0.11, April +0.29, May +0.29, June +0.37, July +0.28, August +0.34, November +0.28, December +0.20 degrees.

The data for 2013 is: January +0.50 degrees, February +0.18, March +0.20, April +0.10, May +0.07, June +0.30, July +0.17, August +0,16, September +0.37, October +0.29, November +0.19, December +0.23 degrees.

The data for 2014 is: January +0.30 degrees, February +0.18, March +0.17, April +0.19, May +0.33, June +0.31, July +0.30, August +0.20, September +0.30, October +0.37, November +0.33, and December +0.33 degrees Celsius.

The data for 2015 is: January +0.20 degrees C, February +0.18 degrees C, March +0.14 degrees C, April +0.07 degrees C, May +0.30 degrees C, June +0.32 degrees C, July +0.18 degrees C, August +0.22 degrees C, September +0.20 degrees C, October +0.32 degrees C, November +0.40 degrees C, and December +0.48 degrees C.

The data for 2016 is: January +0.55 degrees C,  February +0.83 degrees C, March  +0.73 degrees C, April +0.71 degrees C, May +0.55  degrees, June +0.33 degrees C, July +0.39 degrees C, August +0.38 degrees C, September  +0.44 degrees C, October +0.35 degrees, November +0.40 degrees C, and December +0.24 degrees C.

The data for 2017 is: January +0.31 degrees C, February +0.35 degrees C, March +0.37 degrees C,  April +0.40 degrees C ,  May  +0.47 degrees C , and June  +0.21 degrees C.      

The coolest months since 1979 were September 1984, with minus 0.49 degrees Celsius, and November 1984, with minus 0.42 degrees Celsius.

The warmest months were February 2016 with plus 0.83 degrees C, February and April 1998, both plus 0.76 degrees Celsius, and March 2016 plus 0.73 degrees, and April 2016 plus 0.73 degrees Celsius.

The chart shows the El Nino warming in the 1998 period, and 2015-16, and the Mount Pinatubo, volcanic cooling during 1992-1993.

Details: http://www.drroyspencer.com/latest-global-temperatures/

For further information see:  https://sites.google.com/site/climatediceandthebutterfly




Tauranga June Rainfalls 1898-2017

Weather Eye
with John Maunder

The methodology use in adjusting the older sites to the current observing site is published in the ‘NZ Meteorological Service Miscellaneous Publication' No 180 in 1984.

It is considered that the homogeneous rainfall series described here is a fair and true record of what the rainfall would have been if the current observation site (Tauranga Airport) had been used since 1898, with the understanding that although standard accepted methodologies have been used, any adjustments are only estimates of what would have occurred if the location of the rainfall records had always been in the same place with the same surroundings and the same or similar recording gauge.

In terms of climate change (such as is it getting wetter or drier, or warmer or colder), the methodology used in computing an ‘official' set of climate observations is very important, as otherwise erroneous conclusions may be drawn.

The graph shows the range of rainfalls from an extreme high of 381 mm in 1925 to a low of 19 mm in 1906. There is a small decrease in the overall June rainfalls during the last 50 years, from 1961-2010, from an average of 126 mm, compared with an average of 139 mm during the 50 years from 1911-1960.

Since 1898, there have been 17 June months with a rainfall of 200 mm or more, and 11 June months with rainfalls of 50 mm or less.

In chronological order the wettest 17 June months are: 1915, 1917, 1920, 1925, 1930, 1935, 1939, 1943, 1946, 1961, 1968, 1971, 1981, 1985, 1997, 2010, and 2014.

By contrast the driest June months in chronological order are: 1906, 1913, 1914, 1933, 1942, 1958, 1959, 1967, 2001, 2012, and 2015.





The Maunder Minimum and Sunspots

Weather Eye
with John Maunder

The ‘Maunder Minimum' is the name given to the period from 1645 to 1715 when the number of sunspots – ‘storms' on the sun – became almost zero.

The period is named after the solar astronomer Edward Walter Maunder (1851-1928), who was working at The Royal Observatory at Greenwich when he discovered the dearth of sunspots during this period.

During one 30-year period within the Maunder Minimum there were only about 50 sunspots compared with a more typical 40,000.

Maunder was a driving force in the foundation of the British Astronomical Association and a fellow of the Royal Astronomical Society.

The sun was well observed during the period of the Maunder Minimum and this lack of sunspots is well documented.

 

This period of solar inactivity corresponded to a climatic period called the ‘Little Ice Age' when in Europe rivers that were normally ice-free, froze and snow fields remained at low altitudes throughout the year.

There is evidence the sun had similar periods of inactivity during the years 1100-1250 and 1460-1550.

Sunspots generally follow a cycle of about 11 years, but cycles have varied from eight-15 years.

The connection between solar activity and the earth's climate is an area of ongoing and sometimes controversial research. 

Time will tell whether the sun will once again go into another ‘Maunder Minimum' within the lifetime of the present generation, but if this happens we're likely have a much colder climate for a few decades.

 

A sunspot is a relatively dark, sharply defined region on the solar disc – marked by an umbra, dark area, which is 2000 degrees cooler than the effective photospheric temperature.

The average diameter of a sunspot is 4000 km, but they can exceed 200,000 km.

The NASA solar physics website, and other websites such as the Royal Observatory of Belgium, include information on sunspot numbers, the ‘Maunder Minimum' and sunspot cycle predictions.

The sunspot index is updated monthly and available from 1749. The last time the monthly sunspot number was above 100 during the last 14 years was in September 2002, when the value was 110. February 2014 had a sunspot value of 102.

The last time the value was above 200 was in August 1990, when the value was 200.3 – and there were no sunspots observed in September 2009. The value for June 28, 2017 is 27. 

For further information contact John Maunder at climate@ihug.co.nz



Tauranga May Average Afternoon Temperatures 1913-2017

Weather Eye
with John Maunder

The average afternoon temperature in Tauranga in May 2017 was a relatively cool 17.6 degrees Celsius.

In contrast,  May 2016 was was equal with May 1916 as the warmest May on record, both recording 19.3 degrees.

Temperatures have been recorded in the Tauranga area at several sites during the last 100 years, including the current Tauranga Airport site from June 1990.

 

It's very common for areas, such as Tauranga, to have experienced different observation sites during the years – and the readings from the earlier sites have been adjusted to the present site using standard climatological procedures.

It's considered the temperature series described here is a fair and true record of what the temperature would have been if the current observation site (of Tauranga Airport) had been used throughout the period.

Traditionally, temperature observations have been recorded with a set of maximum and minimum temperature thermometers.

These record the daily maximum temperature – usually recorded in mid-afternoon – and daily minimum temperature – usually recorded just before dawn.

This analysis of temperatures for Tauranga is for the average daily maximum temperatures.

The graph shows details of the average daily maximum temperatures, called simply ‘afternoon', for Tauranga for May from 1913-2017. May 1964 is not included because of incomplete data.

The long-term average afternoon temperature in May for Tauranga is 16.9 degrees Celsius, ranging from the cool May months of 1936, 1940, and 1997 with an average afternoon temperature of 14.9 degrees Celsius, to the warm May months of 1916 and 2016 both with an average afternoon temperature of 19.3 degrees Celsius, May 2011 with 19.1 degrees Celsius, and May 2007 with 18.9 degrees Celsius.

The graph of the average afternoon temperatures for May shows generally normal variations from May to May.

However, the last 20 May months have been a little warmer than other May months since 1913.

From 1913 to 2016, there have been 14 May months with an average afternoon temperature of 18 degrees Celsius or more, and 11 May months with an average afternoon temperature of less than 16 degrees Celsius.

The value for May 2013 was 18.5 degrees Celsius, which is the sixth warmest on record, and for May 2014 the temperature was 18.4 degrees Celsius – the seventh warmest on record, and May 2016 which was equal first warmest on record.

The 14 warmest May months, in terms of afternoon temperatures, on record in chronological order are: 1916, 1928, 1938, 1950, 1999, 2000, 2003, 2005, 2007, 2010, 2011, 2013, 2014, and 2016.

In contrast, the 11 coolest May months, in terms of afternoon temperatures, on record in chronological order are: 1913, 1920, 1924, 1936, 1940, 1945, 1959, 1967, 1977, 1983, and 1992.

The average afternoon temperature in May during the 49-year period 1914-1962 was 16.7 degrees Celsius, compared with 17.1 degrees Celsius for the 49-year period from 1963-2011.

 

- See more at: http://www.sunlive.co.nz/blogs/10985-tauranga-may-average-afternoon-temperatures-19132017.html#sthash.UQpokG8m.dpuf



Tauranga May Rainfalls 1898-2017

Weather Eye
with John Maunder

The May rainfall in Tauranga in 2017 was 154 mm.

 

Apart from the exceptional rainfall of 634 mm in May 2005, the graph shows a small decrease in overall May rainfalls when two recent adjacent 50-year periods are compared.

Since 1898, there have been 14 May months with a rainfall of 200 mm or more. In chronological order, the wettest May months are: 1899, 1900, 1917, 1925, 1926, 1928, 1949, 1950, 1956, 1961, 1962, 1971, 2005, and 2010.

In terms of dry May months, there have been only nine May months with a rainfall of less than 40 mm.

In chronological order, the driest May months are: 1901, 1918, 1939, 1941, 1978, 1991, 1999, 2007, and 2014. Of particular significance is the exceptional rainfall in May 2005.

I estimated that such a rainfall is likely to occur in Tauranga only about twice in every 1000 years.

This suggests central government could have had a much more important role in the financial implications of the floods, which affected many areas of Tauranga in May 2005 that occurred.

- See more at: http://www.sunlive.co.nz/blogs/10965-tauranga-may-rainfalls-18982017.html#sthash.ARhYV9bl.dpuf


Tauranga April Average Afternoon Temperatures 1913-2017

Weather Eye
with John Maunder

Temperatures have been recorded in the Tauranga area at several sites during the last 100 years, including the current Tauranga Airport site from June 1990.

It's very common for areas such as Tauranga to have had different observation sites during the years – and the readings from the earlier sites have been adjusted to the present site using standard climatologically procedures.

The temperature series, as shown in the graph, are based on the data from the original observations from the various sites as available on the NIWA National Climate Database archive, with data from the sites prior to the Tauranga Airport site being adjusted, where appropriate, to temperatures which are likely to have been recorded at the current airport site.

Traditionally, temperature observations have been recorded with a set of maximum and minimum temperature thermometers.

These record the daily maximum temperature (usually recorded in mid-afternoon), and the daily minimum temperature (usually recorded just before dawn).

The graph shows details of the average daily maximum temperatures (called simply ‘afternoon'), for Tauranga for April from 1913-2017. Note April 1947 and 1964 are not included because of incomplete data.

The long-term average afternoon temperature in April for Tauranga for is 20.0 degrees Celsius, ranging from the cool April months of 1925, with an average afternoon temperature of 18.2 degrees Celsius, and 1923 with an average afternoon temperature of 18.3 degrees Celsius, to the warm April months of 1938 (22.2 degrees Celsius), and 1916 (22.1 degrees Celsius).

The graph of the average afternoon temperatures for April shows generally normal variations from April to April, but several of the last 20 April months have been  a little warmer than other April months.

From 1913 to 2017, there have been 15 April months with an average afternoon temperature of 21.0 degrees Celsius or more, and eight April months with an average afternoon temperature of less than 19.0 degrees Celsius.

The value for April 2017 was 20.9 degrees Celsius,

The 15 warmest April months – in terms of afternoon temperatures – on record, in chronological order, are 1916, 1924, 1928, 1935, 1938, 1948, 1955, 1956, 1978, 1981, 2010, 2012, 2013, 2014, and 2016. In contrast, the eight coolest April months – in terms of afternoon temperatures – on record, in chronological order, are 1923, 1925, 1940, 1941, 1949, 1980, 1991 and 1992.

The average afternoon temperatures for Tauranga for the 50 years 1914-1962, and the 50-year period 1963-2011 are both 20.0 degrees Celsius.

- See more at: http://www.sunlive.co.nz/blogs/10938-tauranga-april-average-afternoon-temperatures-19132017.html#sthash.gfCyMYVr.dpuf


Tauranga April Rainfalls 1898-2017

        
Weather Eye
with John Maunder

Rainfalls in Tauranga during the month of April 2013 and April 2014 and April 2017 were all relatively wet, with April 2013 recording 284 mm – the seventh highest April rainfall since 1898 – and in April 2014 the total was 225 mm – the 16th highest April rainfall in the city since 1898.

April 2017 had a rainfall of 293 mm, the sixth highest rainfall for April.

 

The graph shows the range of rainfalls from a high of 383 mm in 1911 to a low of 10 mm in 1958.

The second wettest April was 1948, when 333 mm was recorded; and the second driest was April 2010 with only 12 mm.

The long-term average rainfall for Tauranga for April is 120 mm.

Since 1898, there have been 11 April months with a rainfall of 250 mm or more.

In chronological order, the wettest April months are: 1911, 1923, 1935, 1938, 1948, 1959, 1995, 2000, 2001, 2013, and 2017.

In terms of dry April months, there have been nine months with rainfall of 30 mm or less.

In chronological order, the driest April months are: 1898, 1910, 1913, 1919, 1958, 1979, 1984, 2005, and 2010.

- See more at: http://www.sunlive.co.nz/blogs/10911-tauranga-april-rainfalls-18982017.html#sthash.rrLfu0Z9.dpuf

******





Climate Extremes in NZ: Tauranga has one of them

Weather Eye
with John Maunder

Climate extremes in New Zealand, since instrumental records became available in the 1850's, show a range from the highest temperature of 42.4 degrees Celsius recorded in Rangiora on February 7, 1973, to the most intense rainfall in 10 minutes – 34 mm which occurred in Tauranga on April 17, 1948.

The National Institute of Water and Atmospheric Research (NIWA) updates the weather extremes recorded in New Zealand since observations were officially recorded in the 1850's.

The current extremes up to December 2016 include the following:

Wettest: A record 34 mm occurred in 10 minutes in Tauranga on April 17, 1948. In one hour, 134 mm was recorded  at Cropp at Waterfall in the Hokitika Catchment. This site also has the NZ record for the highest 24 hours' fall of 758 mm on December 27-28, 1989, and the highest 48-hour-fall of 1049 mm on December 11-13, 1995. It also had the highest fall in a calendar month of 2827 mm in December 1995, and the highest fall in a calendar year of 16,617 mm in 1998.

Driest: Only 9 mm of rain fell at Cape Campbell, Marlborough, from January to March 2001; the driest three months ever recorded in New Zealand. The driest six months was also recorded at Cape Campbell, from November 2000 to April 2001 when only 52 mm of rain was recorded. The driest 12 months was in Alexandra from November 1963 to October 1964, when only 167 mm was recorded. The longest period without rain is 71 days, which occurred in Wai-iti, Marlborough, from February 8, 1939.

Warmest: Until 1973, the highest temperatures officially recorded in New Zealand was 101.3 degrees Fahrenheit (38.4 degrees Celsius) at Ashburton and Darfield on January 19, 1956. However, under extreme northwesterly conditions on February 7, 1973, there was a recorded 42.4 degrees Celsius (108.3 degrees Fahrenheit) at Rangiora. A temperature of 42.3 degree Celsius was also recorded on this day at Jordan, Marlborough.

Coldest: The coldest air temperature ever recorded was minus 25.6 degrees Celsius in Eweburn, Ranfurly, on July 17, 1903. The lowest grass temperature is minus 21.6 degrees Celsius recorded at Lake Tekapo on August 4, 1938.

Sunniest: Nelson, Takaka, Riwaka, Blenheim, Lake Tekapo, Tauranga and Whakatane often appear in the list of very sunny places in New Zealand – but officially Richmond has recorded the most sunshine in any one year with 2840 hours in 2016. In the North Island, Whakatane recorded 2792 hours of sunshine in 2012.

In contrast, only 1333 hours of sunshine was recorded in Invercargill in 1983. For one month, the sunniest locations Nelson with 336 hours in December 1934, and New Plymouth also recording 336 hours in January 2015; and the least sunny location is Taumaranui, with only 27 hours in June 2002.

Wind Gust: The highest wind gusts recorded in New Zealand were 250 km/h at Mt John, Canterbury, on April 17, 1970 and 248 km/h at Hawkins Hill, Wellington, on November 6, 1959, and July 4, 1962.

- See more at: http://www.sunlive.co.nz/blogs/10863-climate-extremes-new-zealand-tauranga-has-one-of-them.html#sthash.4M6vtRrf.dpuf


Villach and Climate Change

Weather Eye
with John Maunder

Among the many climate science meetings I've attended, the most significant – at least in terms of climate change is concerned – was my involvement in the UN-sponsored International Conference in Villach, Austria, in October 1985.

About 100 from 30 countries attended this meeting – in contrast to the 25,000 who now attend such meetings – and I was privileged to be the only New Zealander invited.

We were all there as experts – not representing our respective organisations or necessarily the views of our respective Governments – in various fields of science, endeavouring to do the best we could in looking at the complexities of climate science.

Among principal findings of this conference was: “while other factors, such as aerosol concentration, changes in solar energy input, and changes in vegetation, may also influence climate, greenhouse gases are likely to be the most important cause of climate change over the next century”.

At the time, even though I was partly responsible for the writing of the above paragraph, I along with a few of my colleagues, had some misgivings about this phrase.

And I was somewhat surprised that within a year ‘human-induced global warming' caught the imagination of many around the world.

Today not a day goes by without some mention of global warming, climate change etc – all terms which up until 1980 were the preserve of academic text books,  and terms such as ‘emission trading schemes',  weren't even thought.

Despite this concern, a colleague of mine from Australia, Bill Kininmonth, who in 2004 wrote an excellent book called ‘Climate Change - A Natural Hazard' has mentioned to me on several occasions that I've changed from being a ‘gamekeeper' and become the ‘poacher'.

Whether this is true is a matter of opinion. However, irrespective of my personal views on the matter, it's clear there are two main views held by climate scientists and others on the subject of global warming and climate change.

First, those mainly involved in the Intergovernmental Panel on Climate Change IPCC) and many or most government scientists, plus others, such as Al Gore, many politicians and most journalists who consider humans and human activity, including domestic animals, is the prime cause of recent changes in the climate.

Second, there are are those – including some university scientists, several retired climatologists and climate scientists, and a minority of politicians and journalists, who consider nature is the main cause of changes in the climate

Thirty years ago it was unconceivable the New Zealand Government  and most other governments in the world would have a Minister of Climate Change.

Back then, as weather forecasters and climatologists, we just got on with our job of making the best possible weather forecast and providing the best climate advice to all who requested information – without guidance or interference from the Government of the day.

How things have changed.

- See more at: http://www.sunlive.co.nz/blogs/10828-villach-and-climate-change.html#sthash.bG54TrPn.dpuf


The State of the climate in 2016

Weather Eye
with John Maunder

A report on the State of the Climate in 2016 which is based exclusively on observations rather than climate models was published on March 22, 2017 by the Global Warming Policy Foundation (GWPF).

 

The report is compiled by Dr Ole Humlum, Professor of Physical Geography at the University Centre in Svalbard (Norway). The new climate survey is in sharp contrast to the habitual alarmism of other reports that are mainly based on computer modelling and climate predictions.

Among the key findings of the survey are:

  • While 2016 was one of the warmest years on record, global temperatures dropped back at the end of the year to levels prior to the strong 2015/16 El Niño. This fact suggests that much of the global 2015–16 temperature peak was caused by a one of the strongest El Niños on record.
  • Since 2003, the global temperature estimate based on surface station measurements has consistently drifted away from the satellite-based estimate in a warm direction, and is now about 0.1◦C higher.
  • Much of the heat given off during the 2015–16 El Niño appears to have been transported to the polar regions, especially to the Arctic, causing severe weather phenomena and unseasonably high air temperatures.
  • Data from tide gauges all over the world suggest an average global sea-level rise of 1–1.5 mm/year, while the satellite-derived record suggests a rise of more than 3 mm/yr. This noticeable difference between the two data sets still has no broadly accepted explanation.
  • Arctic and Antarctic sea-ice extents since 1979 have developed in opposite directions, decreasing and increasing, respectively. In the Arctic, a 5.3-year periodic variation is important, while for the Antarctic a cycle of about 4.5 years duration is important. Both these variations reached their minima simultaneously in 2016, which explains the recent minimum in global sea-ice extent.

Prof Humlum said: “There is little doubt that we are living in a warm period. However, there is also little doubt that current climate change is not abnormal and not outside the range of natural variations. 

http://www.thegwpf.org/the-worlds-first-state-of-the-climate-survey-based-on-observations-only/

- See more at: http://www.sunlive.co.nz/blogs/10801-the-state-of-climate-2016.html#sthash.ZKCjQ7p1.dpuf


The New Zealand Drought Index

Weather Eye
with John Maunder

A new tool to monitor drought conditions across New Zealand has been launched by the National Institute of Water and Atmospheric Research (NIWA).

Called The New Zealand Drought Index (NZDI), it is an easy-to-use, colour coded map that defines the scientifically observed drought status of every New Zealand district.

The NZDI is modelled on similar indexes used around the world, displaying the dryness of each district in five categories: dry, very dry, extremely dry, drought and severe drought. Each category is colour coded from yellow for dry, through to dark red for severe drought.

NIWA has developed the index in conjunction with the Ministry for Primary Industries (MPI) over the past two years.

The new index will be used by MPI as one of the criteria, alongside the wider impact on the rural community, to determine whether a drought is a medium or large scale adverse event. The Minister for Primary Industries then decides what support and recovery measures should be made available.

NIWA climate scientist Dr Andrew Tait says the index is based on the most up-to-date science and the information is automatically updated daily.

“We would like this initiative to be seen as the premier index for drought in New Zealand. It is a climate data-based indicator based on four commonly-used climatological drought indicators.”

These are:  the Standardised Precipitation Index, the Soil Moisture Deficit, the Soil Moisture Deficit Anomaly, and the Potential Evapotranspiration Deficit.

The index is presented as a map and as charts, enabling people to select districts and climatological indicators to keep track of particular areas.

Dr Tait says that “This is a useful tool for farmers, irrigators, regional councils, water managers and anyone who needs to know about dry conditions. They can rely on the science behind the index to monitor what is happening in their area. It is the place to go look at current drought indicators around New Zealand.”

While the map covers the whole of New Zealand, the charts have the ability for people to seek more information about a particular district. It is searchable by date and any combination of the drought indicators. 

The NZDI can be accessed at www.niwa.co.nz/drought-index 

- See more at: http://www.sunlive.co.nz/blogs/10792-the-new-zealand-drought-index.html#sthash.xWrg1YJS.dpuf


The Southern Oscillation Index (SOI)


Weather Eye
with John Maunder

The Southern Oscillation Index (SOI) is a standardized index based on the observed sea level pressure differences between Tahiti and Darwin, Australia.

The SOI is a leading measure of the large-scale fluctuations in air pressure occurring between the western and eastern tropical Pacific (i.e., the state of the Southern Oscillation) during El Niño and La Niña episodes.

In general, smoothed time series of the SOI correspond very well with changes in ocean temperatures across the eastern tropical Pacific. 

The negative phase of the SOI represents below-normal air pressure at Tahiti and above-normal air pressure at Darwin. 

The positive phase of the SOI represents above-normal air pressure at Tahiti and below-normal air pressure at Darwin. 

Prolonged periods of negative SOI values coincide with abnormally warm  ocean waters across the eastern tropical Pacific typical of El Niño episodes. 

In contrast, prolonged periods of positive SOI values coincide with abnormally cold ocean waters across the eastern tropical Pacific typical of La Niña episodes. 

Sustained negative values of the SOI below −8 often indicate El Niño episodes.

These negative values are usually accompanied by sustained warming of the central and eastern tropical Pacific Ocean, a decrease in the strength of the Pacific Trade Winds.

Sustained positive values of the SOI above +8 are typical of a La Niña episode.

They are associated with stronger Pacific trade winds and warmer sea temperatures to the north of Australia. Waters in the central and eastern tropical Pacific Ocean become cooler during this time.

The graph below ( from the Bureau of Meteorology in Australia) shows monthly values of the SOI in recent years updated to mid April 2017. 

The El Niño-Southern Oscillation (ENSO) is neutral. However, model outlooks and recent warming in the Pacific Ocean mean there is an increased chance of El Niño forming later this year. The Australian Bureau of Meteorology  ENSO Outlook is currently at El Niño WATCH, which means the likelihood of El Niño forming this year is around double the average chance at 50%.

Most atmospheric and oceanic indicators of ENSO are currently neutral. However, sea surface temperatures (SSTs) in the eastern Pacific Ocean have warmed since the start of the year, and the Southern Oscillation Index (SOI) has been trending downwards. While these are fairly typical changes in the lead up to El Niño, trade winds and cloudiness have not shown any significant shift away from neutral.

All eight international models surveyed by the Bureau show steady warming of the central tropical Pacific Ocean over the next six months. Six models suggest El Niño thresholds may be reached by July 2017. However, some caution must be taken, as models have lower accuracy when forecasting through the autumn months than at other times of the year.

El Nino and La Nina weather affects over New Zealand (source Niwa)

During El Niño, New Zealand tends to experience stronger or more frequent winds from the west in summer, typically leading to drought in east coast areas and more rain in the west.

In winter, the winds tend to be more from the south, bringing colder conditions to both the land and the surrounding ocean.

In spring and autumn south–westerly winds are more common.

La Niña events have different impacts on New Zealand's climate. More north–easterly winds are characteristic, which tend to bring moist, rainy conditions to the north–east of the North Island, and reduced rainfall to the south and south–west of the South Island.

Therefore, some areas, such as central Otago and South Canterbury, can experience drought in both El Niño and La Niña.

Warmer than normal temperatures typically occur over much of the country during La Niña, although there are regional and seasonal exceptions.

Although ENSO events have an important influence on New Zealand's climate, it accounts for less than 25 per cent of the year to year variance in seasonal rainfall and temperature at most New Zealand measurement sites.

- See more at: http://www.sunlive.co.nz/blogs/10759-the-southern-oscillation-index-soi.html#sthash.QRFO0Jha.dpuf


WMO Day, March 23, 2017

        
Weather Eye
with John Maunder

The World Meteorological Organization WMO), is the successor of the International Meteorological Organization (IMO) which was created in 1873.

Its fundamental mission is to support the countries of the world in providing meteorological and hydrological services to protect life and property from natural disasters related to weather, climate, and water, to safeguard the environment, and to contribute to sustainable development.

This cannot happen without the necessary observations, research and operations that develop the understanding and knowledge of weather and climate.

Since 1961, World Meteorological Day has commemorated the coming into force on 23 March 1950 of the Convention establishing the World Meteorological Organization  (WMO) and the essential contribution that National Meteorological and Hydrological Services make to the safety and well-being of society.

Each year, the celebrations focus on a theme of topical interest.

The theme for the 2015 World Meteorological Day  “Climate knowledge for climate action,” provided an opportunity to take stock of the climate knowledge built during the last decades, as an essential base to support the path towards more ambitious action to address climate change and climate variability.

The NZ MetService communications meteorologist Lisa Murray says that “Understanding Clouds” the theme of World Meteorological Day this year, is to highlight the enormous importance of clouds for weather climate and water.

It also marks the launch of the new edition of the International Cloud Atlas, the single authoritative and most comprehensive reference for identifying clouds and a treasure trove of hundreds of images of clouds, including a few newly-classified cloud types.

To celebrate World Meteorological Day here in New Zealand, the MetService is showcasing a collection of cloud photos, taken by New Zealanders, on their website's Social Media Gallery.

The structure of the WMO which has headquarters in Geneva involves the Congress, the Executive Council, and eight Technical Commissions.

The World Meteorological Congress, the supreme body of the Organization, assembles delegates of Members (countries) once every four years to determine general policies for the fulfilment of the purposes of the Organization; to consider membership of the Organization; to determine the general, technical, financial and staff regulations; to establish and coordinate the activities of constituent bodies of the Organization; to approve long-term plans and budget for the following financial period; to elect the President and Presidents of the Organization and members of the Executive Council; and to appoint the Secretary-General. The Executive Council is the executive body of the Organization, which meets annually, implements decisions of Congress, coordinates the programmes, examines the utilization of budgetary resources, considers and takes action on recommendations of regional associations and technical commissions and guides their work programme, provides technical information, counsel and assistance in the fields of activity of the Organization and studies and takes action on matters affecting international meteorology and related activities.

The Council is composed of 37 directors of National Meteorological or Hydrometeorological Services, serving in an individual capacity as representatives of the Organization and not as representatives of particular Members thereof.

They include the President and three Vice-Presidents who are elected by Congress, and the presidents of the six regional associations.

The remaining 27 members are elected by Congress.

There are also eight Technical Commissions which are composed of experts designated by Members and are responsible for studying meteorological, climatological, and hydrological operational systems, applications and research.

They establish methodology and procedures and make recommendations to the Executive Council and the Congress. The Technical Commissions usually meet once every four years, when they elect a President* and Vice-President.  

*From 1989 to 1996, I was President of one of Technical Commissions, namely the “Commission for Climatology” .

In addition, three others from New Zealand have been Presidents of WMO Technical Commissions, Dr Jim Salinger (Commission for Agricultural Meteorology), Dr Neil Gordon ( Commission for Aeronautical Meteorology), and Dr John Gabites (Commission  for Atmospheric Sciences).

- See more at: http://www.sunlive.co.nz/blogs/10681-wmo-day-march-23-2017.html#sthash.MElvB7Y8.dpuf


Tropospheric Global Temperatures - 1979 to February 2017

Weather Eye
with John Maunder

The chart below shows that since 1979, when reliable satellite observations became available, there has been little overall trend from the average temperatures during the 30-year period from 1981-2010 in the tropospheric temperatures, apart from a period of somewhat warmer temperatures since about 1997, and two significant warm periods associated with the El Nino events in 1998 and 2015-16.

The latest global average temperatures of the troposphere – those observed from US National Oceanic and Atmospheric Administration satellites – are computed by the University of Alabama at Huntsville in the United States.

The troposphere is the lowest layer of Earth's atmosphere.

It contains approximately 75 per cent of the atmosphere's mass and 99 per cent of its water vapour and aerosols.

The average depth of the troposphere is approximately 17 km in the middle latitudes.

The tropospheric temperature data for 2011 is January 0.0 degrees Celsius, February -0.02, March -0.10, April +0.12, May +0.14, June +0.32, July +0.38, August +0.33, September +0.29, October +0.12, November +0.12, December +0.10 degrees.

The data for 2012 is: January -0.09 degrees, February -0.12, March +0.11, April +0.29, May +0.29, June +0.37, July +0.28, August +0.34, November +0.28, December +0.20 degrees.

The data for 2013 is: January +0.50 degrees, February +0.18, March +0.20, April +0.10, May +0.07, June +0.30, July +0.17, August +0,16, September +0.37, October +0.29, November +0.19, December +0.23 degrees.

The data for 2014 is: January +0.30 degrees, February +0.18, March +0.17, April +0.19, May +0.33, June +0.31, July +0.30, August +0.20, September +0.30, October +0.37, November +0.33, and December +0.33 degrees Celsius.

The data for 2015 is: January +0.20 degrees C, February +0.18 degrees C, March +0.14 degrees C, April +0.07 degrees C, May +0.30 degrees C, June +0.32 degrees C, July +0.18 degrees C, August +0.22 degrees C, September +0.20 degrees C, October +0.32 degrees C, November +0.40 degrees C, and December +0.48 degrees C.

The data for 2016 is: January +0.55 degrees C,  February +0.83 degrees C, March  +0.73 degrees C, April +0.71 degrees C, May +0.55  degrees, June +0.33 degrees C, July +0.39 degrees C, August +0.38 degrees C, September  +0.44 degrees C, October +0.35 degrees, November +0.40 degrees C, and December +0.24 degrees C.

The data for 2017 is: January +0.31 degrees C, February +0.35 degrees C.

The coolest months since 1979 were September 1984, with minus 0.49 degrees Celsius, and November 1984, with minus 0.42 degrees Celsius.

The warmest months were February 2016 with plus 0.83 degrees C, February and April 1998, both plus 0.76 degrees Celsius, and March 2016 plus 0.73 degrees, and April 2016 plus 0.73 degrees Celsius.

The chart shows the El Nino warming in the 1998 period, and 2015-16, and the Mount Pinatubo, volcanic cooling during 1992-1993.

- See more at: http://www.sunlive.co.nz/blogs/10654-tropospheric-global-temperatures-1979-to-february-2017.html#sthash.dh4oQLHo.dpuf

Tauranga February Average Afternoon Temperatures 1914-2017

Weather Eye
with John Maunder

This is the 200th issue of WeatherEye

Temperatures have been recorded in the Tauranga area at several sites during the last 100 years, including the current Tauranga Airport site from June 1990.

It's very common for areas such as Tauranga to have had different observation sites during the years; and the readings from the earlier sites have been adjusted to the present site using ‘standard climatological procedures'.

It's considered the temperature series described here is a fair and true record of what the temperature would have been if the current observation site (Tauranga Airport) had been used throughout the period.

It's important to note that in considering ‘climate change', the methodology used in computing an 'official' set of climate observations is very important – as otherwise erroneous conclusions may be drawn.

Traditionally, temperature observations have been recorded with a set of maximum and minimum temperature thermometers. These record the daily maximum temperature (usually recorded in mid-afternoon), and daily minimum temperature (usually recorded just before dawn).

This analysis of February temperatures for Tauranga is for the average daily maximum temperatures.

 The graph above shows details of the average daily maximum temperatures (called simply ‘afternoon'), for Tauranga for February from 1914-2017.

The long-term average afternoon temperature in February for Tauranga is 23.8 degrees Celsius, ranging from the ‘cool' February months of 1934, with an average afternoon temperature of 21.6 degrees C , and 1921 with an average afternoon temperature of 21.8 degrees Celsius, to the ‘warm' February months of 1916 (26.4 degrees Celsius), and 1998 (26.2 degrees Celsius).

The graph of the average afternoon temperatures for February shows generally 'normal' variations from February to February.

The average afternoon February temperature for the 49 years from 1963-2011 of 24.0 degrees Celsius: this is just 0.3 degrees Celsius higher than the average afternoon February temperature for the 49 years from 1914-1962.

From 1914 to 2017, there have been six February months with an average afternoon temperature of 25.5 degrees Celsius or more, and six February months with an average afternoon temperature of 22.5 degrees Celsius or less.

The average afternoon temperature for February this year was  24.7 degrees Celsius.

The six ‘warmest' February months (in terms of afternoon temperatures) on record, in chronological order, are: 1916, 1928, 1954, 1955, 1998, and 2011.

In contrast the six ‘coolest' February months (in terms of afternoon temperatures) on record, in chronological order, are: 1921, 1931, 1934, 1940, 1976, and 2004.

- See more at: http://www.sunlive.co.nz/blogs/10594-tauranga-february-average-afternoon-temperatures-19142017.html#sthash.aOCseUuh.dpuf










Tauranga Annual Rainfalls 1898-2016

Weather Eye
with John Maunder

Monthly rainfalls for Tauranga have been recorded at several recording sites during the last 118 years.

From January 1898 to December 1904, the observation site was described as the Tauranga Harbour, from November 1904 to April 1907 the site was described as simply ‘Tauranga'.From January 1910 to December 1923 the site was Waikareao, in Otumoetai; from January 1924 to September 1940 the site was at 148 Waihi Rd, in Judea; from October 1940 to January 1941 the site was at Te Puna; and from February 1941 to now, the site is Tauranga Airport.

The methodology use in adjusting the older sites to the current observing site is published in the ‘NZ Meteorological Service Miscellaneous Publication' No 180 in 1984.

It is considered that the homogeneous rainfall series described here is a fair and true record of what the rainfall would have been if the current observation site (Tauranga Airport) had been used since 1898.

This should be coupled with the understanding that although standard accepted methodologies have been used, any adjustments are only estimates of what would have occurred if the location of the rainfall records had always been in the same place with the same surroundings and the same or similar recording gauge.

In terms of climate change (such as is it getting wetter or drier, or warmer or colder), the methodology used in computing an ‘official' set of climate observations is very important, as otherwise erroneous conclusions may be drawn.

The graph below shows the  annual rainfalls at Tauranga from the period 1898-2016.

 

The long-term average rainfall for Tauranga for the calendar year is 1300 mm, ranging from a low of 747 mm in 2002, to a high of 2049 mm in 1962.

For comparison, the rainfall for the last year, 2016, was 1302 mm, with 842 mm recorded in 2015.

Since 1898, there have been only five years with a rainfall of less than 900 mm, they are 1914, 1982, 1993, 2002, and 2015.

And there's only been four years with a rainfall of more than 1800 mm; they are the two consecutive years of 1916 and 1917, plus 1938 and 1962.

The ten wettest years on record are: 1962 which had 2049 mm or 57 per cent above of the long-term average, while 1917 had 1985 mm or 52 per cent above average. Also, 1916 had 1941 mm or 49 per cent above average, plus 1938 (1817 mm), 1920 (1789 mm), 1956 (1777 mm), 1979 (1730 mm), 2011 (1696 mm), 2005 (1682 mm), and 1935 (1670 mm).

In chronological order, these wettest years occurred in 1916, 1917, 1920, 1935, 1938, 1956, 1962, 1979, 2005 and 2011.

In contrast, the 11 driest years on record are: 2002 (747 mm or 48 per cent below the long-term average), 1914 (773 mm or 41 per cent below the long-term average), 1982  and 2015 (842 mm or 36 per cent below the long-term average), plus 1993 (863 mm), 1906 (950 mm), 1919 (962 mm), 1997 (978 mm), 1973 (989 mm), 1986 (991 mm), and 1999 (1002 mm).

In chronological order, these driest years occurred in 1906, 1914, 1919, 1973, 1982, 1986, 1993, 1997, 1999, 2002, and 2015.

The average rainfall in Tauranga for the 50 years 1911-60 was 1365 mm, compared with the average rainfall for the 50 years 1961-2010  of 1263 mm. This indicates a decrease of 100 mm  over the last 50 years compared with the previous 50 years.

- See more at: http://www.sunlive.co.nz/blogs/10417-tauranga-annual-rainfalls-18982016.html#sthash.qwd5Q8Sd.dpuf








Tauranga Average Afternoon Temperatures December 1913-2016

        
Weather Eye
with John Maunder

Temperatures have been recorded in the Tauranga area at several sites during the last 100 years, including the current Tauranga Airport site from June 1990.

The average afternoon temperature in December 2016 was 22.3 degrees Celsius, only 0.1 degrees warmer the average over the last 104 years.

The graph below shows details of the average daily maximum temperatures, called simply ‘afternoon', for Tauranga for December from 1913-2016.

 

The long-term average afternoon temperature in December for Tauranga is 22.1 degrees Celsius, ranging from the ‘cool' December months of 2004 (20.1), 1968 (20.5) and 1944 and 1951 (both 20.7), to the ‘warm' December months of 1940 (24.4), 1937 (24.0), and 1990 (23.8).

The graph of the average afternoon temperatures for December shows generally normal variations from December-to-December during the last 100 years.

The average December afternoon temperature during the 50 years from 1963 to 2011 of 22.2 degrees Celsius which is the same as that  recorded in the 50 years from 1914 to 1961.

The average afternoon temperature of 23.0 degrees Celsius or more, and 12 December months with an average afternoon temperature of less than 21.0 degrees Celsius or less.

The seven warmest December months (in terms of afternoon temperatures), on record, in chronological order, are 1930, 1934, 1937, 1940, 1990, 1993, and 1994.

By contrast, the seven coolest December months (in terms of afternoon temperatures), on record, in chronological order, are 1921, 1946, 1951, 1962, 1968, 1977, and 2004.

- See more at: http://www.sunlive.co.nz/blogs/10393-tauranga-average-afternoon-temperatures-december-19132016.html#sthash.tvqEuLM7.dpuf


In the Bleak Mid-winter


        
Weather Eye
with John Maunder

In the bleak mid-winter,

Frosty wind made moan,

Earth stood hard as iron,

Water like a stone,

Snow had fallen,

Snow on snow, Snow on snow,

In the bleak mid-winter,

Long ago.

These words, from the first verse of the well-known carol, were written by the English poet Christina Rossetti in 1872 in response to a request from the magazine ‘Scribner's Monthly' for a Christmas poem.

It was published posthumously in Rossetti's ‘Poetic Works' in 1904.

The poem became a Christmas carol after it appeared in ‘The English Hymnal' in 1906.

The text of this Christmas poem has been set to music many times; the most famous settings being composed by Gustav Holst and Harold Edwin Darke in the early 20th Century.

The version by Darke is favoured by cathedral choirs, and is the one usually heard performed on the radio broadcasts of ‘Nine Lessons and Carols' by the King's College choir.

The carol featured in the Queen's Christmas TV  message a few years ago. Of some significance is that three years ago on December 15, 2013, the ‘Mail Online' (UK) had the following headlines relating to a severe snow storm, which hit the Holy City  – and at the same time Cairo experienced its first snowfall in more than 100 years. Perhaps a reminder that Christmas carols  do come alive?

A Christmas card come to Life: Jerusalem hit by worst snowstorm for 20 years, as eight inches fall across Holy City.

- Unusually heavy snowfall, as temperatures dip below freezing.

- Dome of the Rock and Western Wall bathed in white blanket.

- Prime Minister Natanyahu gets in on the fun with family snowball fight.

As all my readers will be aware, the weather is always with us; and although we may all hope that the weather this Christmas and in 2017  will be to our liking, it is perhaps important to remember that in the Southern Hemisphere where the carol ‘In the Bleak Mid-Winter' may seem unusual, there have been two significant and tragic events.

The first was on Christmas Eve in New Zealand, in 1953, when the Tangiwai rail disaster occurred with loss of 151 lives, caused by a volcanic lahar from the crater lake on Mount Ruapehu.

The second was in Darwin, in Australia on Christmas Day 1974, when Tropical Cyclone Tracy killed 71 people and destroyed 80 per cent of the city's houses.

I take this opportunity of wishing all my readers a very happy Christmas and I will be back in 2017 with some more WeatherEyes.





Tauranga November Average Afternoon Temperatures 1913-2016

        
Weather Eye
with John Maunder

During November 2013, Tauranga had its warmest November ( average afternoon temperature of 22.3 degrees Celsius), since records began in 1913.

Since then the November temperatures have been 20.5 degrees Celsius in 2014, 20.7 degrees Celsius in 2015, and 21.0 degrees Celsius in 2016.

Temperatures have been recorded in the Tauranga area at several sites in the last 100 years, including the current Tauranga Airport site from June 1990.

The graph shows details of the average daily maximum temperatures (called simply ‘afternoon') for Tauranga for Novembers from 1913-2016.

 

The long-term average afternoon temperature in November for Tauranga is 20.1 degrees Celsius, ranging from the cool November months of 1976 (18.4 degrees Celsius), and 1941 (18.5 degrees Celsius), to the warm November months of 2013 (22.3 degrees Celsius), and 1954 (22.0 degrees Celsius).

The graph of the average afternoon temperatures for November shows generally normal variations from November to November during the last 100 years, but of note are the four warm Novembers in the years 2009, 2010, 2011, and 2013.

The average November afternoon temperature during the 50 years from 1963 to 2011 of 20.1 degrees Celsius, is nearly the same as the 20 degrees Celsius recorded in the 50 years 1914 to 1961.

From 1913 to 2016, there have been 16 November months with an average afternoon temperature of 21.0 degrees Celsius or more, and seven November months with an average afternoon temperature of less than 19.0 degrees Celsius.

The seventh warmest November months (in terms of afternoon temperatures), on record, in chronological order, are 1945, 1954, 1961, 1982, 2010, 2011, and 2013.

By contrast, the seventh coolest November months (in terms of afternoon temperatures), on record, in chronological order, are 1918, 1930, 1946, 1968, 1976, 1991, and 1985.




Tauranga November Rainfalls 1898-2016

Weather Eye
with John Maunder

The graph shows the range of November rainfalls from 1898 to 2016 in Tauranga, from an extreme high of 285 mm in 1916 to a low of only 12 mm in 2009.

 

The second wettest November was 1967, when 240 mm was recorded; the second driest November was in 2011, when only 13 mm fell.

The long-term average rainfall for Tauranga in the month of November is 85 mm. The rainfall for November 2016 was 78 mm.

The graph of the November rainfall shows at first glance normal variations from year to year.

However, there has been a notable decrease in the November rainfalls during the last few years.

Indeed, the average November rainfall in Tauranga for the 50-year period from 1961-2010 of 78 mm is only 85 per cent of the rainfall for the 50-year period 1910-1960.

Since 1898, there have been 11 November months with a rainfall of 150 mm or more (seven of which occurred during the period 1913-1952).

In chronological order, the wettest Novembers are: 1913 with 205 mm, 1916 with 285 mm, 1925 with 167 mm, 1933 with 152 mm, 1936 with 153 mm, 1938 with 174 mm, 1952 with 232 mm, 1967 with 240 mm, 1981 with 191 mm, 1995 with 204 mm, and 1999 with 160 mm.

In terms of dry Novembers, there have been 13 months with rainfall of 30 mm of less, four of which have occurred since 1997.

In chronological order the driest Novembers are 1901 14 mm, 1902 26 mm, 1914 with 17 mm, 1919 with 23 mm, 1928 with 28 mm, 1945 with 20 mm, 1963 with 30 mm, 1982 with 24 mm, 1984 with 19 mm, 1997 with 24 mm, 2009 with 12 mm, 2011 with 13 mm, and 2012 with 27 mm.




Tauranga November Average Afternoon Temperatures 1913-2016


Weather Eye
with John Maunder

During November 2013, Tauranga had its warmest November ( average afternoon temperature of 22.3 degrees Celsius), since records began in 1913.

Since then the November temperatures have been 20.5 degrees Celsius in 2014, 20.7 degrees Celsius in 2015, and 21.0 degrees Celsius in 2016.

Temperatures have been recorded in the Tauranga area at several sites in the last 100 years, including the current Tauranga Airport site from June 1990.

The graph shows details of the average daily maximum temperatures (called simply ‘afternoon') for Tauranga for Novembers from 1913-2016.

 

The long-term average afternoon temperature in November for Tauranga is 20.1 degrees Celsius, ranging from the cool November months of 1976 (18.4 degrees Celsius), and 1941 (18.5 degrees Celsius), to the warm November months of 2013 (22.3 degrees Celsius), and 1954 (22.0 degrees Celsius).

The graph of the average afternoon temperatures for November shows generally normal variations from November to November during the last 100 years, but of note are the four warm Novembers in the years 2009, 2010, 2011, and 2013.

The average November afternoon temperature during the 50 years from 1963 to 2011 of 20.1 degrees Celsius, is nearly the same as the 20 degrees Celsius recorded in the 50 years 1914 to 1961.

From 1913 to 2016, there have been 16 November months with an average afternoon temperature of 21.0 degrees Celsius or more, and seven November months with an average afternoon temperature of less than 19.0 degrees Celsius.

The seventh warmest November months (in terms of afternoon temperatures), on record, in chronological order, are 1945, 1954, 1961, 1982, 2010, 2011, and 2013.

By contrast, the seventh coolest November months (in terms of afternoon temperatures), on record, in chronological order, are 1918, 1930, 1946, 1968, 1976, 1991, and 1985.

- See more at: http://www.sunlive.co.nz/blogs/10336-tauranga-november-average-afternoon-temperatures-19132016.html#sthash.vbliCg9A.dpuf





http://www.sunlive.co.nz/blogs/10261-tropospheric-global-temperatures-1979-to-october-2016.html

Tropospheric Global Temperatures 1979 to October 2016

        
Weather Eye
with John Maunder

The chart below shows that since 1979, when reliable satellite observations became available, there has been little overall trend from the average temperatures during the 30-year period from 1981-2010 in the tropospheric temperatures, apart from a period of somewhat warmer temperatures since about 1997, and two significant warm periods associated with the El Nino events in 1998 and 2015-16.

 

The latest global average temperatures of the troposphere – those observed from US National Oceanic and Atmospheric Administration satellites – are computed by the University of Alabama at Huntsville in the United States.

The troposphere is the lowest layer of Earth's atmosphere.

It contains approximately 75 per cent of the atmosphere's mass and 99 per cent of its water vapour and aerosols.

The average depth of the troposphere is approximately 17 km in the middle latitudes.

The tropospheric temperature data for 2011 is January 0.0 degrees Celsius, February -0.02, March -0.10, April +0.12, May +0.14, June +0.32, July +0.38, August +0.33, September +0.29, October +0.12, November +0.12, December +0.10 degrees.

The data for 2012 is: January -0.09 degrees, February -0.12, March +0.11, April +0.29, May +0.29, June +0.37, July +0.28, August +0.34, November +0.28, December +0.20 degrees.

The data for 2013 is: January +0.50 degrees, February +0.18, March +0.20, April +0.10, May +0.07, June +0.30, July +0.17, August +0,16, September +0.37, October +0.29, November +0.19, December +0.23 degrees.

The data for 2014 is: January +0.30 degrees, February +0.18, March +0.17, April +0.19, May +0.33, June +0.31, July +0.30, August +0.20, September +0.30, October +0.37, November +0.33, and December +0.33 degrees Celsius.

The data for 2015 is: January +0.20 degrees C, February +0.18 degrees C, March +0.14 degrees C, April +0.07 degrees C, May +0.30 degrees C, June +0.32 degrees C, July +0.18 degrees C, August +0.22 degrees C, September +0.20 degrees C, October +0.32 degrees C, November +0.40 degrees C, and December +0.48 degrees C.

The data for 2016 is: January +0.55 degrees C,  February +0.83 degrees C, March  +0.73 degrees C, April +0.71 degrees C, May +0.55  degrees, June +0.33 degrees C, July +0.39 degrees C, August +0.38 degrees C, September  +0.44 degrees C, and October 0.41 degrees C. 

The coolest months since 1979 were September 1984, with minus 0.49 degrees Celsius, and November 1984, with minus 0.42 degrees Celsius.

The warmest months were February 2016 with plus 0.83 degrees C, February and April 1998, both plus 0.76 degrees Celsius, and March 2016 plus 0.73 degrees, and April 2016 plus 0.73 degrees Celsius.

The chart shows the El Nino warming in the 1998 period, and 2015-16, and the Mount Pinatubo, volcanic cooling during 1992-1993.

For further information see:  https://sites.google.com/site/theweatherclimateeye/

- See more at: http://www.sunlive.co.nz/blogs/10261-tropospheric-global-temperatures-1979-to-october-2016.html#sthash.iXTe1SwF.dpuf






The Southern Oscillation Index (SOI)

        
Weather Eye
with John Maunder

The Southern Oscillation Index (SOI) is a standardized index based on the observed sea level pressure differences between Tahiti and Darwin, Australia.

The SOI is a leading measure of the large-scale fluctuations in air pressure occurring between the western and eastern tropical Pacific (i.e., the state of the Southern Oscillation) during El Niño and La Niña episodes.

In general, smoothed time series of the SOI correspond very well with changes in ocean temperatures across the eastern tropical Pacific.  

The negative phase of the SOI represents below-normal air pressure at Tahiti and above-normal air pressure at Darwin.  

The positive phase of the SOI represents above-normal air pressure at Tahiti and below-normal air pressure at Darwin.  

Prolonged periods of negative SOI values coincide with abnormally warm  ocean waters across the eastern tropical Pacific typical of El Niño episodes.  

In contrast, prolonged periods of positive SOI values coincide with abnormally cold ocean waters across the eastern tropical Pacific typical of La Niña episodes.  

Sustained negative values of the SOI below −8 often indicate El Niño episodes.

These negative values are usually accompanied by sustained warming of the central and eastern tropical Pacific Ocean, a decrease in the strength of the Pacific Trade Winds.

Sustained positive values of the SOI above +8 are typical of a La Niña episode.

They are associated with stronger Pacific trade winds and warmer sea temperatures to the north of Australia. Waters in the central and eastern tropical Pacific Ocean become cooler during this time.

The graph below ( from the Bureau of Meteorology in Australia) shows monthly values of the SOI in recent years updated to early November 2016.

 

Outlooks from the eight international climate models surveyed by the Australian Bureau of Meteorology continue to indicate that neutral conditions are the most likely outcome for the Southern Hemisphere spring–summer period. However, two models indicate the likelihood of a brief, late-starting La Niña over the summer.

El Nino and La Nina weather affects over New Zealand (source Niwa)

During El Niño, New Zealand tends to experience stronger or more frequent winds from the west in summer, typically leading to drought in east coast areas and more rain in the west.

In winter, the winds tend to be more from the south, bringing colder conditions to both the land and the surrounding ocean.

In spring and autumn south–westerly winds are more common.

La Niña events have different impacts on New Zealand's climate. More north–easterly winds are characteristic, which tend to bring moist, rainy conditions to the north–east of the North Island, and reduced rainfall to the south and south–west of the South Island.

Therefore, some areas, such as central Otago and South Canterbury, can experience drought in both El Niño and La Niña.

Warmer than normal temperatures typically occur over much of the country during La Niña, although there are regional and seasonal exceptions.

Although ENSO events have an important influence on New Zealand's climate, it accounts for less than 25 per cent of the year to year variance in seasonal rainfall and temperature at most New Zealand measurement sites.

For further information see:  https://sites.google.com/site/climatediceandthebutterfly/

- See more at: http://www.sunlive.co.nz/blogs/10225-the-southern-oscillation-index-soi.html#sthash.Lwx12Zv1.dpuf






Tauranga October Average Afternoon Temperatures 1913-2016

        
Weather Eye
with John Maunder

Temperatures have been recorded in the Tauranga area at several sites in the last 100 years, including the current Tauranga Airport site from June 1990.

The graph shows details of the average daily maximum temperatures (called simply ‘afternoon') for Tauranga for October from 1913-2016.

 

October 2013 had its warmest October (20.3 degrees Celsius) , since records began in 1913.

Since then afternoon temperatures in October 2014 and October 2015 and October 2016  have been 18.3 and 19.4 and  19.1  degrees Celsius.

The long-term average afternoon temperature in October for Tauranga is 18.1 degrees Celsius, ranging from the cool October months of 1964 (15.7 degrees Celsius), and 1992 (16.5 degrees Celsius), to the warm October months of 2013 (20.3 degrees Celsius), and 1915 (19.9 degrees Celsius).

The graph of the average afternoon temperatures for October shows generally normal variations from October to October during the last 100 years.

The average October afternoon temperatures during the 50 years from 1963-2011 of 18.0 degrees Celsius is slightly cooler than the 18.3 degrees Celsius recorded in the 50 years from 1914-1961.

From 1913 to 2016, there have been fourteen October months with an average afternoon temperature of  19.0 degrees Celsius or more; and eight October months have had an average afternoon temperature of 17.0 degrees Celsius or less.

The five warmest October months (in terms of afternoon temperatures), on record, in chronological order, are 1913, 1915, 1940, 2013, and 2015.

By contrast, the fifth coolest October months (in terms of afternoon temperatures), on record, in chronological order, are 1941, 1964, 1978, 1982, and 1992.

 

For further information see: https://sites.google.com/site/theweatherclimateeye/

Tauranga October Rainfalls 1898-2016

        
Weather Eye
with John Maunder

The graph below shows the range of Tauranga's October rainfalls, from an extreme high of 357 mm in 1916 to a low of only 7 mm in 1984.

The second wettest October was 1928, when 269 mm was recorded; and the second driest October was in 1928, when only 11 mm fell.

The long-term average rainfall for Tauranga in the month of October is 110 mm.

The rainfall in October 2016 was 55mm.

The graph of the October rainfall shows at first glance normal variations from year to year.

However, there has been a notable decrease in the October rainfalls during the last few years.

Indeed, the average October rainfall in Tauranga during the 50-year period from 1961-2010 of 88 mm, is only 70 per cent of the rainfall for the 50-year period 1910-1960.

Since 1898, there have been 11 October months with a rainfall of 200 mm or more (10 of which occurred during the period 1900-1958), and only one October month since then has recorded this much. Ten October months have also experienced rainfalls of 25 mm or less.

In chronological order the eleven wettest October months are 1900, 1905, 1916, 1918, 1921, 1926, 1928, 1941, 1952, 1958, and 1983.  In contrast the eleventh driest October months are 1906, 1938, 1963, 1965, 1969, 1973, 1984, 1993, 2010, 2013, and 2015.

For further information on a range of weather/climate matters see:  https://sites.google.com/site/climatediceandthebutterfly/




Global monthly temperatures 1979-2016

        
Weather Eye
with John Maunder

Professor Ole Humlum, of the Institute of Geosciences, University of Oslo, Norway, maintains a very comprehensive climate web site and much of this WeatherEye is from his website

A graph of five global monthly temperatures January 1979 to August/September 2016 is shown below.

The graph shows a superimposed plot of Quality Class 1, and Quality Class 2, and Quality Class 3 global monthly temperature estimates from five international recording agencies

As the base period differs for the different temperature estimates, they have all been normalised by comparing to the average value of 30 years from January 1979 to December 2008.

The heavy black line represents the simple running 37 month mean of the average of all temperature records. The numbers shown in the lower right corner represent the temperature anomaly relative to the individual 1979-2008 averages.

For further information visit: https://sites.google.com/site/climatediceandthebutterfly/




Latest global troposphere temperatures

        
Weather Eye
with John Maunder

The chart below shows that since 1979, when reliable satellite observations became available, there has been little overall trend from the average temperatures during the 30-year period from 1981-2010 in the tropospheric temperatures, apart from a period of somewhat warmer temperatures since about 1997, and two significant warm periods associated with the El Nino events in 1998 and 2015-16.

The latest global average temperatures of the troposphere – those observed from US National Oceanic and Atmospheric Administration satellites – are computed by the University of Alabama at Huntsville in the United States.

The troposphere is the lowest layer of Earth's atmosphere.

It contains approximately 75 per cent of the atmosphere's mass and 99 per cent of its water vapour and aerosols.

The average depth of the troposphere is approximately 17 km in the middle latitudes.

The tropospheric temperature data for 2011 is January 0.0 degrees Celsius, February -0.02, March -0.10, April +0.12, May +0.14, June +0.32, July +0.38, August +0.33, September +0.29, October +0.12, November +0.12, December +0.10 degrees.

The data for 2012 is: January -0.09 degrees, February -0.12, March +0.11, April +0.29, May +0.29, June +0.37, July +0.28, August +0.34, November +0.28, December +0.20 degrees.

The data for 2013 is: January +0.50 degrees, February +0.18, March +0.20, April +0.10, May +0.07, June +0.30, July +0.17, August +0,16, September +0.37, October +0.29, November +0.19, December +0.23 degrees.

The data for 2014 is: January +0.30 degrees, February +0.18, March +0.17, April +0.19, May +0.33, June +0.31, July +0.30, August +0.20, September +0.30, October +0.37, November +0.33, and December +0.33 degrees Celsius.

The data for 2015 is: January +0.20 degrees C, February +0.18 degrees C, March +0.14 degrees C, April +0.07 degrees C, May +0.30 degrees C, June +0.32 degrees C, July +0.18 degrees C, August +0.22 degrees C, September +0.20 degrees C, October +0.32 degrees C, November +0.40 degrees C, and December +0.48 degrees C.

The data for 2016 is: January +0.55 degrees C,  February +0.83 degrees C, March  +0.73 degrees C, April +0.71 degrees C, May +0.55  degrees, June +0.33 degrees C, July +0.39 degrees C, August +0.38 degrees C, and September  +0.44 degrees C.  

The coolest months since 1979 were September 1984, with minus 0.49 degrees Celsius, and November 1984, with minus 0.42 degrees Celsius.

The warmest months were February 2016 with plus 0.83 degrees C, February and April 1998, both plus 0.76 degrees Celsius, and March 2016 plus 0.73 degrees, and April 2016 plus 0.73 degrees Celsius.

The chart shows the El Nino warming in the 1998 period, and 2015-16, and the Mount Pinatubo, volcanic cooling during 1992-1993.

For further information see:  https://sites.google.com/site/theweatherclimateeye/



Tauranga September Average Afternoon Temperatures 1913-2016

        
Weather Eye
with John Maunder

Temperatures have been recorded in the Tauranga area at several sites in the last 100 years, including the current Tauranga Airport site from June 1990.

 

The graph shows details of the average daily maximum temperatures (simply called “afternoon”) for Tauranga for September from 1913-2015.

The long-term average afternoon temperature in September for Tauranga is 16.6 degrees C, ranging from the “cool” September months of 1964 (14.8 degrees C), and 1977 (14.9 degrees C), to the “warm” September months of 1915 (18.4 degrees C), and 18.3 degrees in 1914.

The afternoon temperature for 2015 was 16.1 degrees C, which made it the coolest September for 11 years.

In contrast, September 2016 had an average afternoon temperature of 16.7 degrees C, which was very close to the average over the last 100 years.

The graph of the average afternoon temperatures for September shows generally "normal" variations from September to September during the last 100 years, but five of the warmest six September months occurred from 1913 to 1921.

From 1913 to 2016, there have been ten September months with an average afternoon temperature of 17.5 degrees C or more, and eight September months with an average afternoon temperature of less than 15.4 degrees C.

The tenth “warmest” September months (in terms of afternoon temperatures) on record, in chronological order, are 1913, 1914, 1915, 1916, 1921, 1926, 1940, 2006, 2009 and 2014.

By contrast, the eighth “coolest” September months (in terms of afternoon temperatures) on record, in chronological order, are 1935, 1964, 1967, 1977, 1992, 1993, 1994 and 1997.

The average afternoon temperature during September for the period 1914-62 was 16.6 degrees, compared with 16.5 degrees from 1963-2011.

For further information see: https://sites.google.com/site/theweatherclimateeye/



http://www.sunlive.co.nz/blogs/10105-taurangasetember-average-afternoon-temperatures-19132016.html

Tauranga September Rainfalls : 1898-2016


Weather Eye
with John Maunder

Rainfalls for the month of September have been recorded in Tauranga since 1898, except for 1904, 1907, 1908, and 1909.

The graph below shows the range of rainfalls from an extreme high of 274 mm in 1973 to a low of only 16 mm in 1965.

The second wettest September was in 1900, when 256 mm was recorded, and the second driest September was in 1944, when only 27 mm fell. The long-term average rainfall for Tauranga for September is 105 mm.

 

The graph of the September rainfall shows normal variations from year to year. Since 1898, there have been five Septembers with a rainfall of 200 mm or more (four of which occurred during the period 1900 to 1928, but there's only been one since then), compared with six September months with a rainfalls of 40 mm or less.

The rainfall for September 2016 was 166 mm, which was the eleventh wettest September on record, and the wettest since 1973.

In chronological order, the ten wettest September months (rainfalls over 180 mm) are 1900,1912,1919,1923,1928,1946,1960,1969,1971 and 1973.

In contrast the eleven driest September months (rainfalls of 50 mm or less) are 1910, 1913, 1914, 1921, 1922, 1944, 1965, 1993, 1987, 2006 and 2011.

The average rainfall for Tauranga for September for the 50 years 1961-2010 of 103 mm is similar to the rainfall for the previous 50 years (1910-1960).




**************

El Niño and La Niña :The Southern Oscillation Index


Weather Eye
with John Maunder

El Niño and La Niña are complex weather patterns resulting from variations in ocean temperatures in the Equatorial Pacific.

El Niño and La Niña are opposite phases of what is known as the El Niño-Southern Oscillation (ENSO) cycle.

La Niña is sometimes referred to as the cold phase of the ENSO cycle, and El Niño as the warm phase of ENSO.

These deviations from normal surface temperatures can have large-scale impacts not only on ocean processes, but also on global weather and climate.

El Niño and La Niña episodes typically last nine to 12 months, but some prolonged events may last for years.

While their frequency can be quite irregular, El Niño and La Niña events occur on average every two to seven years. Typically, El Niño occurs more frequently than La Niña.

El Niño

El Niño means The Little Boy, or Christ Child in Spanish. El Niño was originally recognized by fishermen off the coast of South America in the 1600's, with the appearance of unusually warm water in the Pacific Ocean.

The name was chosen based on the time of year (around December) during which these warm waters events tended to occur.

The term El Niño refers to the large-scale ocean-atmosphere climate interaction linked to a periodic warming in sea surface temperatures across the central and east-central Equatorial Pacific.

The presence of El Niño can significantly influence weather patterns, ocean conditions, and marine fisheries across large portions of the globe for an extended period of time.


A typical El Nino weather pattern (Source NIWA)

La Niña

La Niña means The Little Girl in Spanish. La Niña is also sometimes called El Viejo, anti-El Niño, or simply "a cold event."

La Niña episodes represent periods of below-average sea surface temperatures across the east-central Equatorial Pacific.

Global climate La Niña impacts tend to be opposite those of El Niño impacts. In the tropics, ocean temperature variations in La Niña also tend to be opposite those of El Niño.


A typical La Nina weather pattern (source NIWA)

El Nino and La Nina weather affects over New Zealand (source Niwa)

During El Niño, New Zealand tends to experience stronger or more frequent winds from the west in summer, typically leading to drought in east coast areas and more rain in the west.

In winter, the winds tend to be more from the south, bringing colder conditions to both the land and the surrounding ocean.

In spring and autumn south–westerly winds are more common.

La Niña events have different impacts on New Zealand's climate. More north–easterly winds are characteristic, which tend to bring moist, rainy conditions to the north–east of the North Island, and reduced rainfall to the south and south–west of the South Island.

Therefore, some areas, such as central Otago and South Canterbury, can experience drought in both El Niño and La Niña.

Warmer than normal temperatures typically occur over much of the country during La Niña, although there are regional and seasonal exceptions.

Although ENSO events have an important influence on New Zealand's climate, it accounts for less than 25 per cent of the year to year variance in seasonal rainfall and temperature at most New Zealand measurement sites.

East coast droughts may be common during El Niño events, but they can also happen in non El Niño years (for example, the severe 1988–89 drought).

Also, serious east coast droughts do not occur in every El Niño.

However, the probabilities of the climate variations discussed above happening in association with ENSO events are sufficient to warrant management actions and planning to be taken when an El Niño or La Niña is expected or in progress.

My thanks to NIWA for much of the above information.

Southern Oscillation Index:  Current Conditions

The latest 30-day Southern Oscillation Index (SOI)  (assessed by the Australian Bureau of Meteorology) for 11 September 2016 is +8.6, edging over the boundary into La Niña range. The 30-day SOI has hovered around +7 for the past week. The 90-day value is currently +5.9.

Sustained positive values of the SOI above +7 typically indicate La Niña conditions while sustained negative values below −7 typically indicate El Niño conditions. Values between about +7 and −7 generally indicate neutral conditions.




********************

Global Average Temperatures of the Troposphere 1979 to August 2016


Weather Eye
with John Maunder

The latest global average temperatures of the troposphere – those observed from US National Oceanic and Atmospheric Administration satellites – are computed by the University of Alabama at Huntsville in the United States.

 

The above chart shows that since 1979, when reliable satellite observations became available, there has been little overall trend from the average temperatures during the 30-year period from 1981-2010 in the tropospheric temperatures, apart from a period of somewhat warmer temperatures since about 1997, and two significant warm periods associated with the El Nino events in 1998 and 2015-16.

The troposphere is the lowest layer of Earth's atmosphere.

It contains approximately 75 per cent of the atmosphere's mass and 99 per cent of its water vapour and aerosols.

The average depth of the troposphere is approximately 17 km in the middle latitudes.

The tropospheric temperature data for 2011 is January 0.0 degrees Celsius, February -0.02, March -0.10, April +0.12, May +0.14, June +0.32, July +0.38, August +0.33, September +0.29, October +0.12, November +0.12, December +0.10 degrees.

The data for 2012 is: January -0.09 degrees, February -0.12, March +0.11, April +0.29, May +0.29, June +0.37, July +0.28, August +0.34, November +0.28, December +0.20 degrees.

The data for 2013 is: January +0.50 degrees, February +0.18, March +0.20, April +0.10, May +0.07, June +0.30, July +0.17, August +0,16, September +0.37, October +0.29, November +0.19, December +0.23 degrees.

The data for 2014 is: January +0.30 degrees, February +0.18, March +0.17, April +0.19, May +0.33, June +0.31, July +0.30, August +0.20, September +0.30, October +0.37, November +0.33, and December +0.33 degrees Celsius.

The data for 2015 is: January +0.20 degrees C, February +0.18 degrees C, March +0.14 degrees C, April +0.07 degrees C, May +0.30 degrees C, June +0.32 degrees C, July +0.18 degrees C, August +0.22 degrees C, September +0.20 degrees C, October +0.32 degrees C, November +0.40 degrees C, and December +0.48 degrees C.

The data for 2016 is: January +0.55 degrees C,  February +0.83 degrees C, March  +0.73 degrees C, April +0.71 degrees C, May +0.55  degrees, June +0.33 degrees C, July +0.39 degrees C, and August +0.44 degrees C.

The coolest months since 1979 were September 1984, with minus 0.49 degrees Celsius, and November 1984, with minus 0.42 degrees Celsius.

The warmest months were February 2016 with plus 0.83 degrees C, February and April 1998, both plus 0.76 degrees Celsius, and March 2016 plus 0.73 degrees, and April 2016 plus 0.73 degrees Celsius.

The chart shows the El Nino warming in the 1998 period, and 2015-16, and the Mount Pinatubo, volcanic cooling during 1992-1993.


Tauranga August Average Afternoon Temperatures 1913-2016


Weather Eye
with John Maunder

Temperatures have been recorded in the Tauranga area at several sites in the last 100 years, including the current Tauranga Airport site from June 1990.

The graph shows details of the average daily maximum temperatures, called simply ‘afternoon' for Tauranga for August from 1913-2015. The average for August 2015 was 15.1 degrees Celsius.

 

The long-term average afternoon temperature in August for Tauranga is 14.8 degrees Celsius. The coolest August months have been 1932 with 13.8 degrees Celsius, and 1941 and 1992 recording 13.9 degrees Celsius.

The warm August months have been 2013 with 16.7 degrees Celsius, and 1915 with 16.4 degrees Celsius, while 2009 had 16.2 degrees Celsius.

The graph of the average afternoon temperatures for August shows generally normal variations from August to August during the last 100 years.

But several recent August months have been a little warmer than others since 1913.  This includes August 2013, the warmest on record with a temperature of 16.7 degrees Celsius, which was 1.9 degrees Celsius above average.

In comparison, the value for August 2016 was 15.1 degrees Celsius, which made it 1.6 degrees Celsius colder than August 2013.

From 1913 to 2015, there have been 11 August months with an average afternoon temperature of 15.8 degrees Celsius or more.

Thirteen August months have had an average afternoon temperature of less than 14.3 degrees Celsius.

The sixth warmest August months – in terms of afternoon temperatures – on record in chronological order are: 1915, 1967, 1971, 2009, 2012 and 2013. By contrast, the fifth coolest August months – in terms of afternoon temperatures – on record, in chronological order are: 1932, 1941, 1966, 1992 and 2004.

The average afternoon temperatures during August for the period 1914-1962 were 14.7 degrees Celsius, compared with 15.0 degrees Celsius from 1963 to 2011.



******************




Tauranga August Rainfalls 1898-2016


Weather Eye
with John Maunder

Rainfalls for the month of August have been recorded in Tauranga since 1898, except for 1904, 1907, 1908 and 1909.

From January 1898 to December 1904, the observation site was described as the Tauranga Harbour, from November 1904 to April 1907 the site was described as simply ‘Tauranga'. From January 1910 to December 1923 the site was Waikareao, in Otumoetai; from January 1924 to September 1940 the site was at 148 Waihi Rd, in Judea; from October 1940 to January 1941 the site was at Te Puna; and from February 1941 to now, the site is Tauranga Airport.

The methodology use in adjusting the older sites to the current observing site is published in the ‘NZ Meteorological Service Miscellaneous Publication' No 180 in 1984.

It is considered that the homogeneous rainfall series described here is a fair and true record of what the rainfall would have been if the current observation site (Tauranga Airport) had been used since 1898.

This should be coupled with the understanding that although standard accepted methodologies have been used, any adjustments are only estimates of what would have occurred if the location of the rainfall records had always been in the same place with the same surroundings and the same or similar recording gauge.

In terms of climate change (such as is it getting wetter or drier, or warmer or colder), the methodology used in computing an ‘official' set of climate observations is very important, as otherwise erroneous conclusions may be drawn.

 

The graph shows the range of rainfalls from an extreme high of 274 mm in 2010 to a low of only 17 mm in 1914.

The second wettest August was 1916 when 263 mm was recorded, and the second driest August was in 1982 when only 31 mm fell.

The long-term average rainfall for Tauranga for August is 124 mm. The rainfall for Tauranga for August  2016 was 75 mm. This was 49 mm below average.

The graph of the August rainfall shows normal variations from year-to-year.

There is a small decrease in the overall August rainfalls during the last 50 years – from 1961-2010 – from an average of 121 mm, compared with an average of 133 mm during the 50 years from 1911-1960. Since 1898, there have been 11 August months with a rainfall of 220 mm or more – with 10 occurring during 1900 to 1976 – and only one August month since then 2010, which was the highest rainfall for any August. Only five August months have had rainfalls of 50 mm or less.

Chronologically, the 11 wettest August months are 1913, 1916, 1920, 1927, 1938, 1942, 1957, 1965, 1970, 1976 and 2010.

In contrast, chronologically the five driest August months are 1914, 1921, 1982, 1983 and 2002.






Global Monthly Temperatures  January 1979 to June/July 2016


Weather Eye
with John Maunder

Professor Ole Humlum, of the Institute of Geosciences, University of Oslo, Norway, maintains a very comprehensive climate web site and much of this WeatherEye is from his website.  See http://www.climate4you.com

A graph of five global monthly temperatures January 1979 to June/July 2016 is shown below.

The graph shows a superimposed plot of Quality Class 1 and Quality Class 2 and Quality Class 3 global monthly temperature estimates.

As the base period differs for the different temperature estimates, they have all been normalised by comparing to the average value of 30 years from January 1979 to December 2008.

The heavy black line represents the simple running 37 month mean of the average of all temperature records.

 

The numbers shown in the lower right corner represent the temperature anomaly relative to the individual 1979-1988 averages.

It should be kept in mind that satellite and surface-based temperature estimates are derived from different types of measurements, and comparing them directly as done in the diagram above therefore may be somewhat problematical.

However, the different types of temperature estimates appear to agree quite well as to the overall temperature variations on a two-three year scale, although on a shorter time scale there are often considerable differences between the individual records.

All five global temperature estimates presently show a general overall stagnation, at least since 2002.

However, there appears to be  small increase (warming) during the last few years. The year 1998 and the current 2015/16 period was affected by the oceanographic El Nino event.

This stagnation doesn't exclude the possibility that global temperatures will begin to increase again later.

On the other hand, it also remains a possibility that Earth just now is passing a temperature peak, and global temperatures will begin to decrease during the coming years.

Time will show which of these two possibilities is correct.

One of several key global temperature graphs is the monthly average surface air temperature calculated by the Goddard Institute for Space Studies, at Columbia University, New York City, USA.

The graph below is updated to July 2016. GISS is a laboratory of the Earth-Sun Exploration Division of NASA's Goddard Space Flight Center and a unit of the Columbia University Earth Institute.

The thick line is the simple running 37 month average, nearly corresponding to a running 3 year average.









Global Average Temperatures of the Troposphere: January 1979 – July 2016


Weather Eye
with John Maunder

The latest global average temperatures of the troposphere – those observed from US National Oceanic and Atmospheric Administration satellites – are computed by the University of Alabama at Huntsville in the United States.

 

The above chart shows that since 1979, when reliable satellite observations became available, there has been little overall trend from the average temperatures during the 30-year period from 1981-2010 in the tropospheric temperatures, apart from a period of somewhat warmer temperatures since about 1997, and two significant warm periods associated with the El Nino events in 1998 and 2015-16.

The troposphere is the lowest layer of Earth's atmosphere.

It contains approximately 75 per cent of the atmosphere's mass and 99 per cent of its water vapour and aerosols.

The average depth of the troposphere is approximately 17 km in the middle latitudes.

The tropospheric temperature data for 2011 is January 0.0 degrees Celsius, February -0.02, March -0.10, April +0.12, May +0.14, June +0.32, July +0.38, August +0.33, September +0.29, October +0.12, November +0.12, December +0.10 degrees.

The data for 2012 is: January -0.09 degrees, February -0.12, March +0.11, April +0.29, May +0.29, June +0.37, July +0.28, August +0.34, November +0.28, December +0.20 degrees.

The data for 2013 is: January +0.50 degrees, February +0.18, March +0.20, April +0.10, May +0.07, June +0.30, July +0.17, August +0,16, September +0.37, October +0.29, November +0.19, December +0.23 degrees.

The data for 2014 is: January +0.30 degrees, February +0.18, March +0.17, April +0.19, May +0.33, June +0.31, July +0.30, August +0.20, September +0.30, October +0.37, November +0.33, and December +0.33 degrees Celsius.

The data for 2015 is: January +0.20 degrees C, February +0.18 degrees C, March +0.14 degrees C, April +0.07 degrees C, May +0.30 degrees C, June +0.32 degrees C, July +0.18 degrees C, August +0.22 degrees C, September +0.20 degrees C, October +0.32 degrees C,. November +0.40 degrees C, and December +0.48 degrees C.

The data for 2016 is: January +0.55 degrees C,  February +0.83 degrees C, March  +0.73 degrees C, April +0.71 degrees C, May +0.55  degrees, June +0.33 degrees C, and July +0.39 degrees C.

The coolest months since 1979 were September 1984, with minus 0.49 degrees Celsius, and November 1984, with minus 0.42 degrees Celsius.

The warmest months were February 2016 with plus 0.83 degrees C, February and April 1998, both plus 0.76 degrees Celsius, and March 2016 plus 0.73 degrees, and April 2016 plus 0.73 degrees Celsius.

The chart shows the El Nino warming in the 1998 period, and 2015-16 periods, and the Mount Pinatubo, volcanic cooling during 1992-1993.






Central England Temperatures since 1650


Weather Eye
with John Maunder

Thermometers, have been available to record air temperatures since the early 1600's, and the first known temperatures were those recorded in England at about 1650.

Various people have been credited with the invention of the thermometer and Galileo Galilei seems to be the first in the early 1600's; with Robert Fludd in 1638 being the first to show a scale to the new invention.

The graph below shows the central England surface air temperature series, which is the longest existing meteorological record. Thin lines show the annual values; and the thick lines show the running 11-year average.

The graphs for the annual, summer and winter temperatures have been prepared using the composite monthly meteorological series, originally painstakingly homogenised and published by the late professor Gordon Manley in 1974. The data series is now updated by the UK's Hadley Centre.

 

Among other things, the graphs show the cold of the 1660-1670 decade, associated with very low sunspot numbers; the 1815-1816, a “year without a summer”, associated with the Mount Tambora volcano in Indonesia; and the warming trend of the last 20 years.

The graph is one of many from the website: http://www.climate4you.com/

It gives links to many official climate data websites, produced by NASA, NOAA, and The University of East Anglia, etc.





Tauranga: Average July Afternoon Temperatures 1913-2016

 
Weather Eye
with John Maunder

The graph below shows details of the average daily maximum temperatures, called ‘afternoon', for Tauranga for July from 1913-2016.

The temperature for July 2016 was 15.2 degrees Celsius, 1.1 degrees milder than July last year, which was the coolest July since July 2004.

It's very common for areas such as Tauranga to have had different observation sites during the years, and readings from the earlier sites have been adjusted to the present site using standard climatologically procedures.

The temperature series described here is a record of what the temperature would have been if the current observation site, Tauranga Airport, had been used throughout the period.

It's important to note, in considering climate change, the methodology used in computing an official set of climate observations is very important as otherwise erroneous conclusions may be drawn.

Traditionally, temperature observations have been recorded with a set of maximum and minimum temperature thermometers.

These record the daily maximum temperature, usually recorded in mid-afternoon, and daily minimum temperature, usually recorded just before dawn.

This analysis of temperatures for Tauranga is for average daily maximum temperatures.

The long-term average afternoon temperature in July for Tauranga is 14.1 degrees Celsius, ranging from cool July months of 1918 and 1939, both 12.3 degrees Celsius, and 1965, with 12.9 degrees Celsius.

Warm July months included 1916 and 2010, both 15.8 degrees Celsius, and 1915 with 15.7 degrees Celsius.

The graph of the average afternoon temperatures for July shows generally normal variations from July to July in the last 100 years.

But several July months since 1997 have been a little warmer than many of the July months since 1913.

From 1913 to 2016, there have been 10 July months with an average afternoon temperature of 15 degrees Celsius or more, and 11 July months with an average afternoon temperature of less than 13.3 degrees Celsius.

The value for July 2016 was 15.2 degrees Celsius, compared with a cool 14.1 degrees Celsius last July ( the coolest July since 2004).

The 11 mildest July months for afternoon temperatures on record, in chronological order are: 1915, 1916, 1917, 1984, 1985, 1998, 2000, 2011, 2012, 2014, and 2016.

By contrast, the seven coolest July months for afternoon temperatures on record, in chronological order are: 1918, 1929, 1935, 1939, 1963, 1965, and 1969.

The average afternoon temperature for Tauranga for July for 49 years from 1914-1962 was 14.0 degrees Celsius, compared with the average afternoon temperature for Tauranga for July for 49 years from 1963-2011 was 14.2 degrees Celsius.



Tauranga July Rainfalls 1898-2016

 0 0Google +0 0
Weather Eye
with John Maunder

Rainfalls for the month of July have been recorded in Tauranga since 1898, except for 1904, 1907, 1908, and 1909.

The graph for the period 1898-2016 shows the range of rainfalls from an extreme high of 348 mm in 1951, to a low of only 2 mm in 1902.

The rainfall for July 2016 was 154mm. The graph shows the second wettest July was 2012 when 328mm was recorded, and the second driest July was in 1983 when only 22mm fell.

The long-term average rainfall for Tauranga for July is 129mm. The graph of the July rainfall shows ‘normal' variations from year to year.

There is a very small decrease in the overall July rainfalls during the last 50 years (1961-2010) from an average of 127 mm, compared with an average of 132 mm during the 50 years from 1911-1960.

Since 1898, there have been 13 July months with a rainfall of 200 mm or more, but only four July months with rainfalls of 40 mm or less.

The ten wettest July months (in chronological order) have been 1905, 1927, 1938, 1951,1963,1979,1988, 2007, 2008, and 2012. The ten driest July months ( in chronological order) have been 1902, 1918, 1922, 1949, 1969, 1975, 1983, 1997, 2001, and 2010, For further information on a variety of weather and climate matters see   https://sites.google.com/site/nzrainfalls/newzealandmonthlyrainfalls


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1816: The Year Without a Summer


Weather Eye
with John Maunder

‘The year without a summer', was caused by dust from volcanic eruption of Mount Tambora in Indonesia, which shrouding the earth after it erupted in early-April 1815.

During the summer, sunlight was blocked which had a number of significant affects. The map below courtesy of the US Geological Survey shows the location of active volcanoes, plate tectonics, and “The Ring of Fire”.

In Switzerland, the damp and dismal summer of 1816 led to the creation of a significant literary work.

A group of writers, including Lord Byron, Percy Bysshe Shelley, and his future wife, challenged each other to write dark tales inspired by the gloomy and chilly weather.

During the miserable weather, Mary Shelley wrote her classic novel Frankenstein.

At the same time, in the United States, the Albany Advertiser proposed some theories about why the weather was so bizarre, which shows the thoughts of an editor over 200 years ago. The mention of sunspots is interesting, as at that time, sunspots had been seen by astronomers. And many people, to this day, wonder about what, if any effect, sunspots may have had on the weird weather.

What's also fascinating is the newspaper article from 1816 proposes such events be studied, so people can learn what is going on. For example:

“Many seem disposed to charge the peculiarities of the season, the present year, upon the spots on the sun.

“If the dryness of the season has in any measure depended on the latter cause, it has not operated uniformly in different places – the sunspots have been visible in Europe, as well as in the United States and yet in some parts of Europe, as we have already remarked, they have been drenched with rain.”

“Without undertaking to discuss, much less to decide, such a learned subject as this, we should be glad if proper pains were taken to ascertain, by regular journals of the weather from year to year, the state of the seasons in this country and in Europe, as well as the general state of health in both quarters of the globe.”

“We think the facts might be collected, and the comparison made, without much difficulty; and when once made, that it would be of great advantage to medical men, and medical science.”

Today, we now know volcanoes can pose many hazards. One hazard is volcanic ash can be a threat to jet aircraft where ash particles can be melted by the high operating temperature. The melted particles then adhere to the turbine blades and alter their shape, disrupting the operation of the turbine.

Large volcanic eruptions can also affect temperature, as ash and droplets of sulphuric acid obscure the sun and cool the Earth's lower atmosphere, or troposphere.

However, they also absorb heat radiated up from the Earth, thereby warming the upper atmosphere, or stratosphere.

Historically, the so-called volcanic winters (in addition to 1815) have caused catastrophic famines.




Solar Activity and the Earth's Climate


Weather Eye
with John Maunder

A sunspot is a relatively dark, sharply defined region on the solar disc - marked by an umbra (dark area) which is 2000 degrees Celsius cooler than the effective photosphere temperature.

The average diameter of a sunspot is 4000 km, but can exceed 200,000 km.

The NASA Solar Physics website (and other web sites such as the Royal Observatory of Belgium) includes information on sunspot numbers, the ‘Maunder Minimum', and sunspot cycle predictions. The sunspot index is updated monthly and available from 1749. The last time the monthly sunspot number was above 100 for any significant period of time was September 2002 when the value was 109.6, and the last time the value was above 200 was in August 1990 when the value was 200.3.

The peak of latest solar cycle Number 24 was reached in April 2014, with a maximum of the 13-month smoothed sunspot number at 81.8. Since then, solar activity has steadily declined. The monthly mean sunspot number is now around 45.

Solar cycle 24 proved to be 30% weaker than the previous solar cycle, which reached 119.7 in July 2000, and thus belongs to the category of moderate cycles, like cycles 12 to 15, which were the norm in the late 19th and early 20th century.

As this late maximum comes more than 5 years after the preceding minimum in December 2008, cycle 24 has now entered its long declining phase, as none of the past observed cycles had longer delays between minimum and maximum. Therefore, the average solar activity should progressively decrease towards a minimum around 2020. However, over the next 2 or 3 years, we can still expect strong but brief peaks of activity caused by the appearance of a few big complex groups, a typical feature of the late phase of solar cycles.

We are currently over six years into solar cycle 24. This the smallest sunspot cycle since solar cycle 14 which had a maximum of 64.2 in February of 1906.

The “Maunder Minimum” period is named after the solar astronomer Edward Walter Maunder (1851-1928), who while working at The Royal Observatory at Greenwich discovered the dearth of sunspots during the 1650-1700 period.

Time will tell whether the sun will once again go into another “Maunder Minimum” within the lifetime of the present generation, and what affect it will have on our climate.


Tauranga June Rainfalls 1898-2016


Weather Eye
with John Maunder

Rainfalls for the month of June have been recorded in Tauranga since 1898 – except for 1904, 1907, 1908 and 1909.

The graph shows the range of rainfalls from an extreme high of 381mm in 1925 to a low of 19mm in 1906.

The second wettest June was 1920, when 309mm was recorded, and the second and third driest June months were in 1959 and 2012 when only 27mm fell.

The monthly average rainfall for Tauranga for June is 131mm.

The graph of the June rainfall shows normal variations from year to year.

There is a small decrease in the overall June rainfalls during the last 50 years, from 1961-2010, from an average of 126mm, compared with an average of 139mm during the 50 years from 1911-1960.

Since 1898, there have been 17 June months with a rainfall of 200mm or more, and 11 June months with rainfalls of 50mm or less.

The estimated rainfall for June 2016 was 160mm. Because of a malfunction in the rainguage, the actual rainfall at the Tauranga Airport was not recorded for one day (which was wet) in the month.

In chronological order the wettest 17 June months are: 1915, 1917, 1920, 1925, 1930, 1935, 1939, 1943, 1946, 1961, 1968, 1971, 1981, 1985, 1997, 2010, and 2014.

By contrast the driest June months in chronological order are: 1906, 1913, 1914, 1933, 1942, 1958, 1959, 1967, 2001, 2012, and 2015.



Tauranga June Average Afternoon Temperatures 1913-2016


Weather Eye
with John Maunder

Temperatures have been recorded in the Tauranga area at several sites during the last 100 years, including at the current Tauranga Airport site from June 1990.

The graph shows details of the average daily maximum temperatures, called simply ‘afternoon', for Tauranga for June from 1913-2016.

 

The long-term average afternoon temperature in June for Tauranga is 14.7 degrees Celsius.

The ‘cool' June months were in 1972 with 13.0 degrees Celsius, 1936 with 13.2 degrees Celsius, and 1933 with 13.3 degrees Celsius.

The ‘warm' June months include last year, 2014 with 16.9 degrees Celsius, 1916 and 2011, both with 16.6 degrees Celsius, and June 2016 with 16.5 degrees Celsius.

June 2014 had an average afternoon temperature of 16.9 degrees Celsius and the warmest June on record since observations were first made in 1913, and this year June had an average afternoon temperatures of 16.5 degrees C.

This compares with an average afternoon temperature in June 2015 of 15.4 degrees Celsius.

The graph of the average afternoon temperatures for June shows generally ‘normal' variations from June to June during the last 100 years.

But many of the last 20 June months since 1996 have been a little ‘warmer' than other June months since 1913.

From 1913 to 2016, there have been 15 June months with an average afternoon temperature of 15.6 degrees Celsius or more, and 12 June months with an average afternoon temperature of less than 13.9 degrees Celsius.

The 10 ‘warmest' June months on record, in chronological order, are: 1916, 1971, 1981, 1998, 1999, 2002, 2003, 2011, 2014, and 2016.

By contrast, the seventh ‘coolest' June months on record, in chronological order, are 1933, 1936, 1941, 1944,1969, 1972 and 1976.

The average afternoon temperature in June during the period 1914-1962 was 14.7 degrees Celsius compared with 14.8 degrees Celsius from 1963 to 2011.



Global Average Temperatures of the Troposphere: January 1969 - May 2016


Weather Eye
with John Maunder

The latest global average temperatures of the troposphere – those observed from US National Oceanic and Atmospheric Administration satellites – are computed by the University of Alabama at Huntsville in the United States.

 

The above chart shows that since 1979, when reliable satellite observations became available, there has been little overall trend from the average temperatures during the 30-year period from 1981-2010 in the tropospheric temperatures, apart from a period of somewhat warmer temperatures since about 1997, and two significant warm periods associated with the El Nino events in 1998 and 2015-16.

The troposphere is the lowest layer of Earth's atmosphere.

It contains approximately 75 per cent of the atmosphere's mass and 99 per cent of its water vapour and aerosols.

The average depth of the troposphere is approximately 17 km in the middle latitudes.

The tropospheric temperature data for 2011 is January 0.0 degrees Celsius, February -0.02, March -0.10, April +0.12, May +0.14, June +0.32, July +0.38, August +0.33, September +0.29, October +0.12, November +0.12, December +0.10 degrees.

The data for 2012 is: January -0.09 degrees, February -0.12, March +0.11, April +0.29, May +0.29, June +0.37, July +0.28, August +0.34, November +0.28, December +0.20 degrees.

The data for 2013 is: January +0.50 degrees, February +0.18, March +0.20, April +0.10, May +0.07, June +0.30, July +0.17, August +0,16, September +0.37, October +0.29, November +0.19, December +0.23 degrees.

The data for 2014 is: January +0.30 degrees, February +0.18, March +0.17, April +0.19, May +0.33, June +0.31, July +0.30, August +0.20, September +0.30, October +0.37, November +0.33, and December +0.33 degrees Celsius.

The data for 2015 is: January +0.20 degrees C, February +0.18 degrees C,  March +0.14 degrees C, April +0.07 degrees C, May +0.30 degrees C, June +0.32 degrees C, July +0.18 degrees C, August +0.22 degrees C, September +0.20 degrees C, October +0.32 degrees C,. November +0.40 degrees C, and December +0.48 degrees C.

The data for 2016 is: January +0.55 degrees C,  February +0.83 degrees C, March  +0.73 degrees C, April +0.71 degrees C, May +0.55  degrees.

The coolest months since 1979 were September 1984, with minus 0.49 degrees Celsius, and November 1984, with minus 0.42 degrees Celsius.

The warmest months were February 2016 with plus 0.83 degrees C, and February and April 1998, both plus 0.76 degrees Celsius.

The chart shows the El Nino warming in the 1998 period, and 2015-16 periods, and the Mount Pinatubo, volcanic cooling during 1992-1993.



Climate Extremes in New Zealand: Tauranga has one of them


Weather Eye
with John Maunder

Climate extremes in New Zealand, since instrumental records became available in the 1850's, show a range from the highest temperature of 42.4 degrees Celsius recorded in Rangiora on February 7, 1973, to the most intense rainfall in 10 minutes – 34 mm which occurred in Tauranga on April 17, 1948.

The National Institute of Water and Atmospheric Research (NIWA) updates the weather extremes recorded in New Zealand since observations were officially recorded in the 1850's.

The current extremes up to December 2015 include the following:

Wettest: A record 34 mm occurred in 10 minutes in Tauranga on April 17, 1948. In one hour, 134 mm was recorded  at Cropp at Waterfall in the Hokitika Catchment.

This site also has the NZ record for the highest 24 hours' fall of 758 mm on December 27-28, 1989, and the highest 48-hour-fall of 1049 mm on December 11-13, 1995. It also had the highest fall in a calendar month of 2827 mm in December 1995, and the highest fall in a calendar year of 16,617 mm in 1998.

Driest: Only 9 mm of rain fell at Cape Campbell, Marlborough, from January to March 2001; the driest three months ever recorded in New Zealand. The driest six months was also recorded at Cape Campbell, from November 2000 to April 2001 when only 52 mm of rain was recorded. The driest 12 months was in Alexandra from November 1963 to October 1964, when only 167 mm was recorded. The longest period without rain is 71 days, which occurred in Wai-iti, Marlborough, from February 8, 1939.

Warmest: Until 1973, the highest temperatures officially recorded in New Zealand was 101.3 degrees Fahrenheit (38.4 degrees Celsius) at Ashburton and Darfield on January 19, 1956. However, under extreme northwesterly conditions on February 7, 1973, there was a recorded 42.4 degrees Celsius (108.3 degrees Fahrenheit) at Rangiora. A temperature of 42.3 degree Celsius was also recorded on this day at Jordan, Marlborough.

Coldest: The coldest air temperature ever recorded was minus 25.6 degrees Celsius in Eweburn, Ranfurly, on July 17, 1903. The lowest grass temperature is minus 21.6 degrees Celsius recorded at Lake Tekapo on August 4, 1938.

Sunniest: Nelson, Takaka, Riwaka, Blenheim, Lake Tekapo, Tauranga and Whakatane often appear in the list of very sunny places in New Zealand – but officially Blenheim has recorded the most sunshine in any one year with 2814 hours in 2015. In the North Island, Whakatane recorded 2792 hours of sunshine in 2012.

In contrast, only 1333 hours of sunshine was recorded in Invercargill in 1983. For one month, the sunniest locations Nelson with 336 hours in December 1934, and New Plymouth also recording 336 hours in January 2015; and the least sunny location is Taumaranui, with only 27 hours in June 2002.

Wind Gust: The highest wind gusts recorded in New Zealand were 250 km/h at Mt John, Canterbury, on April 17, 1970 and 248 km/h at Hawkins Hill, Wellington, on November 6, 1959, and July 4, 1962.



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Tauranga Average Afternoon Temperatures for May 1913-2016


Weather Eye
with John Maunder

May 2016 was equal with May 1916 as the warmest May on record.

Temperatures have been recorded in the Tauranga area at several sites during the last 100 years, including the current Tauranga Airport site from June 1990.

 

It's very common for areas, such as Tauranga, to have experienced different observation sites during the years – and the readings from the earlier sites have been adjusted to the present site using standard climatological procedures.

It's considered the temperature series described here is a fair and true record of what the temperature would have been if the current observation site (of Tauranga Airport) had been used throughout the period.

Traditionally, temperature observations have been recorded with a set of maximum and minimum temperature thermometers.

These record the daily maximum temperature – usually recorded in mid-afternoon – and daily minimum temperature – usually recorded just before dawn.

This analysis of temperatures for Tauranga is for the average daily maximum temperatures.

The graph shows details of the average daily maximum temperatures, called simply ‘afternoon', for Tauranga for May from 1913-2016. May 1964 is not included because of incomplete data.

The long-term average afternoon temperature in May for Tauranga is 16.9 degrees Celsius, ranging from the cool May months of 1936, 1940, and 1997 with an average afternoon temperature of 14.9 degrees Celsius, to the warm May months of 1916 and 2016 both with an average afternoon temperature of 19.3 degrees Celsius, 2011 with 19.1 degrees Celsius, and 2007 with 18.9 degrees Celsius.

The graph of the average afternoon temperatures for May shows generally normal variations from May to May.

However, the last 20 May months have been a little warmer than other May months since 1913.

From 1913 to 2016, there have been 14 May months with an average afternoon temperature of 18 degrees Celsius or more, and 11 May months with an average afternoon temperature of less than 16 degrees Celsius.

The value for May 2013 was 18.5 degrees Celsius, which is the sixth warmest on record, and for May 2014 the temperature was 18.4 degrees Celsius – the seventh warmest on record, and May 2016 which was equal first warmest on record.

The 14 warmest May months, in terms of afternoon temperatures, on record in chronological order are: 1916, 1928, 1938, 1950, 1999, 2000, 2003, 2005, 2007, 2010, 2011, 2013, 2014, and 2016.

In contrast, the 11 coolest May months, in terms of afternoon temperatures, on record in chronological order are: 1913, 1920, 1924, 1936, 1940, 1945, 1959, 1967, 1977, 1983, and 1992.

The average afternoon temperature in May during the 49-year period 1914-1962 was 16.7 degrees Celsius, compared with 17.1 degrees Celsius for the 49-year period from 1963-2011.


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The latest WeatherEye No 162 issued on June 7, 2016

May Rainfalls for Tauranga 1898-2016


Weather Eye
with John Maunder

Rainfalls for the month of May have been recorded in Tauranga since 1898 – except for 1904, 1907, 1908, and 1909.

The graph shows the range of rainfalls from an extreme high of 634 mm in 2005 to a low of 13 mm in 2001.

The rainfall for May 2016 was 89 mm, 36 mm less than average.

 

The second wettest May was 1950, when 311 mm was recorded, and the second driest May was in 1918, when only 24 mm fell.

The long-term average rainfall for Tauranga for May is 124mm.

Apart from the exceptional rainfall of 634mm in May 2005, the graph shows a small decrease in overall May rainfalls when two 50-year periods are compared.

Since 1898, there have been 14 May months with a rainfall of 200 mm or more. In chronological order, the wettest May months are: 1899, 1900, 1917, 1925, 1926, 1928, 1949, 1950, 1956, 1961, 1962, 1971, 2005, and 2010.

In terms of dry May months, there have been only nine May months with a rainfall of less than 40 mm.

In chronological order, the driest May months are: 1901, 1918, 1939, 1941, 1978, 1991, 1999, 2007, and 2014. Of particular significance is the exceptional rainfall in May 2005.

I estimated that such a rainfall is likely to occur in Tauranga only about twice in every 1000 years.

This suggests central government could have had a much more important role in financial implications of the floods, which affected many areas of Tauranga in May 2005.



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The latest WeatherEye No 161 issued on May 30, 2016

Global Temperatures 1880-2015


Weather Eye
with John Maunder

Global temperatures are compiled for various areas, including global (land-ocean), global (meteorological stations), three latitude bands, and hemispheric, by the Goddard Institute for Space Studies of NASA.

A graph of the global temperatures (for the land/ocean) from 1880 to 2016, show a general warming from 1910 to the early 1940's, a cooling from the early 1940's to the mid-1970's; a general warming from the mid-1970's to about 1998; a stable period of temperatures until about the 2012, and  a warming from 2013.

The green bars on the graph show the uncertainty estimates at various times

The yearly global temperatures (expressed as differences from the 1951-1980 average), since 1998 are:

1998:   +0.58 degrees Celsius

1999:   +0.33 degrees Celsius

2000:   +0.35 degrees Celsius

2001:   +0.48 degrees Celsius

2002:   +0.56 degrees Celsius

2003:   +0.56 degrees Celsius

2004:   +0.49 degrees Celsius

2005:   +0.69 degrees Celsius

2006:   +0.63 degrees Celsius

2007:   +0.66 degrees Celsius

2008:   +0.53 degrees Celsius

2009:   +0.64 degrees Celsius

2010:   +0.72 degrees Celsius

2011:   +0.60 degrees Celsius

2012:   +0.63 degrees Celsius

2013:   +0.65 degrees Celsius

2014:   +0.74 degrees Celsius

2015:   +0.87 degrees Celsius


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The latest WeatherEye No 160 issued on May 23, 2016

Villach and Climate Change


Weather Eye
with John Maunder

Among the many climate science meetings I've attended, the most significant – at least in terms of climate change is concerned – was my involvement in the UN-sponsored International Conference in Villach, Austria, in October 1985.

About 100 from 30 countries attended this meeting – in contrast to the 20,000 who now attend such meetings – and I was privileged to be the only New Zealander invited.

We were all there as experts – not representing our respective organisations or necessarily the views of our respective Governments – in various fields of science, endeavouring to do the best we could in looking at the complexities of climate science.

 

Among principal findings of this conference was: “while other factors, such as aerosol concentration, changes in solar energy input, and changes in vegetation, may also influence climate, greenhouse gases are likely to be the most important cause of climate change over the next century”.

At the time, even though I was partly responsible for the writing of the above paragraph, I along with a few of my colleagues, had some misgivings about this phrase.

And I was somewhat surprised that within a year ‘human-induced global warming' caught the imagination of many around the world.

Today not a day goes by without some mention of global warming, climate change etc – all terms which up until 1980 were the preserve of academic text books,  and terms such as ‘emission trading schemes',  weren't even thought.

Despite this concern, a colleague of mine from Australia, Bill Kininmonth, who in 2004 wrote an excellent book called ‘Climate Change - A Natural Hazard' has mentioned to me on several occasions that I've changed from being a ‘gamekeeper' and become the ‘poacher'.

Whether this is true is a matter of opinion. However, irrespective of my personal views on the matter, it's clear there are two main views held by climate scientists and others on the subject of global warming and climate change.

First, those mainly involved in the Intergovernmental Panel on Climate Change IPCC) and many or most government scientists, plus others, such as Al Gore, many politicians and most journalists who consider humans and human activity, including domestic animals, is the prime cause of recent changes in the climate.

Second, there are are those – including some university scientists, several retired climatologists and climate scientists, and a minority of politicians and journalists, who consider nature is the main cause of changes in the climate

Twenty years ago it was unconceivable the New Zealand Government  and most other governments in the world would have a Minister of Climate Change.

Back then, as weather forecasters and climatologists, we just got on with our job of making the best possible weather forecast and providing the best climate advice to all who requested information – without guidance or interference from the Government of the day.

How things have changed.



The latest WeatherEye No 159 issued on May 16, 2016

Planet Earth and climate change

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Weather Eye
with John Maunder

There is an excellent website compiled and updated monthly by Dr Ole Humlum, who is a Danish professor of physical geography at the University of Oslo, and adjunct professor of physical geography at the University Centre in Svalbard.

See http://climate4you.com, the following is complied from his website.

Planet Earth has an age of about 4600 million years. 

Global climate change has been the rule for the entire history of Earth, not the exception.

If each year of planet Earth is represented by one millimetre, the entire stratigraphic history would be about 4600km long. 

In North America, 4600km corresponds to the distance between San Francisco  and Quebec City. On this scale modern humans would appear within the last 200 m, the polar bear within the last 150 m, and the entire global meteorological record since about 1850 would take up the last 160 mm.

From time to time the Earth has been affected by millions of years with relatively cold climate, each such period leading to a long succession of glacial and interglacial periods.

During the last couple of millions of years, planet Earth has been in such a cold stage.

The last (until now) ice age ended around 11,600 years ago, and we are currently living in a so-called interglacial period, until the next ice age which presumably will begin some time into the future.

The last four glacial periods and interglacial periods are shown in the diagram below, covering the last 420,000 years in Earth's climatic history.

 

The diagram above  shows a reconstruction of global temperature based on ice core analysis from the Antarctica.

The present interglacial period (the Holocene) is seen to the right (red square).

The preceding four interglacials are seen at about 125,000, 280,000, 325,000 and 415,000 years before now, with much longer glacial periods in between.

All four previous interglacials are seen to be warmer (by 1 to 3 degrees Celsius) than the present.

The typical length of a glacial period is about 100,000 years, while an interglacial period typical lasts for about 10-15,000 years.

The present interglacial period has now lasted about 11,600 years.

According to ice core analysis, the atmospheric carbon dioxide concentrations during all four prior interglacials never rose above approximately 290 ppm; whereas the atmospheric carbon dioxide concentration today stands at nearly 390 ppm.

The present interglacial is about 2 degrees Celsius colder than the previous interglacial, even though the atmospheric carbon dioxide concentration now is about 100 ppm higher.


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The Latest WeatherEye  No 158 issued on May 9,2016

Tauranga Average April Afternoon Temperatures 1913-2016


Weather Eye
with John Maunder

Temperatures have been recorded in the Tauranga area at several sites during the last 100 years, including the current Tauranga Airport site from June 1990.

It's very common for areas such as Tauranga to have had different observation sites during the years – and the readings from the earlier sites have been adjusted to the present site using standard climatologically procedures.

The temperature series, as shown in the graph, are based on the data from the original observations from the various sites as available on the NIWA National Climate Database archive, with data from the sites prior to the Tauranga Airport site being adjusted, where appropriate, to temperatures which are likely to have been recorded at the current airport site.

Traditionally, temperature observations have been recorded with a set of maximum and minimum temperature thermometers.

These record the daily maximum temperature (usually recorded in mid-afternoon), and the daily minimum temperature (usually recorded just before dawn).

The graph shows details of the average daily maximum temperatures (called simply ‘afternoon'), for Tauranga for April from 1913-2016. Note April 1947 and 1964 are not included because of incomplete data.

 

The long-term average afternoon temperature in April for Tauranga for is 20.0 degrees Celsius, ranging from the cool April months of 1925, with an average afternoon temperature of 18.2 degrees Celsius, and 1923 with an average afternoon temperature of 18.3 degrees Celsius, to the warm April months of 1938 (22.2 degrees Celsius), and 1916 (22.1 degrees Celsius).

The graph of the average afternoon temperatures for April shows generally normal variations from April to April, but several of the last 20 April months have been  a little warmer than other April months.

From 1913 to 2016, there have been 15 April months with an average afternoon temperature of 21.0 degrees Celsius or more, and eight April months with an average afternoon temperature of less than 19.0 degrees Celsius.

The value for April 2016 was 21.0  degrees Celsius, 1.0 degrees Celsius average. This meant that April 2016 was equal to the thirteenth warmest April on record.

The 15 warmest April months – in terms of afternoon temperatures – on record, in chronological order, are 1916, 1924, 1928, 1935, 1938, 1948, 1955, 1956, 1978, 1981, 2010, 2012, 2013, 2014, and 2016. In contrast, the eight coolest April months – in terms of afternoon temperatures – on record, in chronological order, are 1923, 1925, 1940, 1941, 1949, 1980, 1991 and 1992.

The average afternoon temperatures for Tauranga for the 50 years 1914-1962, and the 50-year period 1963-2011 are both 20.0 degrees Celsius.


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Tauranga April Rainfalls 1898-2016


Weather Eye
with John Maunder

Rainfalls in Tauranga during the month of April 2013 and April 2014 were both relatively wet, with April 2013 recording 284 mm – the sixth highest April rainfall since 1898 – and in April 2014 the total was 225 mm – the 17th highest April rainfall in the city since 1898.

In contrast, the rainfalls in Tauranga for April 2015 (116 mm), and April 2016 (87 mm) were about average.

The graph shows the range of rainfalls from a high of 383 mm in 1911 to a low of 10 mm in 1958.

The second wettest April was 1948, when 333 mm was recorded; and the second driest was April 2010 with only 12 mm.

The long-term average rainfall for Tauranga for April is 120 mm.

Since 1898, there have been 10 April months with a rainfall of 250 mm or more.

In chronological order, the wettest April months are: 1911, 1923, 1935, 1938, 1948, 1959, 1995, 2000, 2001, and 2013.

In terms of dry April months, there have been nine months with rainfall of 30 mm or less.

In chronological order, the driest April months are: 1898, 1910, 1913, 1919, 1958, 1979, 1984, 2005, and 2010.


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Climate Change - Methods of Inferring/Detecting Change


Weather Eye
with John Maunder

What causes the climate to change as well as understanding the methods for detecting changes in the climate are on-going research activities.

The following is a brief summary of the methods scientists and others, such as historians, employ in inferring and detecting changes in climate during a variety of time scales. I am indebted to a NIWA web site for much of this summary.

Instrumental measurements

Data from instruments and written or oral records provide quantitative records of temperature and other meteorological records for the last 150 years in New Zealand – and up to 350 years in a few other countries, such as summer, winter, and annual temperature charts for central England from 1659-2015 shown in the graph.

Such records must be analysed carefully, to identify the influence of any non-climate factors, such as changes in observing site or method, or encroaching urban development. Records of sea level and land movements are also important for assessing sea level change.

Source of graph: http://www.climate4you.com/

Proxy data

Beyond the scope of instrumental measurements, information about past climate can be obtained from natural proxy archives, as well as historical records of events, such as harvests etc.

Changes observed in these archives often identify so closely to climate variations they can be used as a substitute for climate records prior to the instrumental record after a careful calibration process has been undertaken.

Piecing evidence together from various natural proxy data sources includes:

Ice cores

Ice cores drilled in Greenland, the Antarctic ice sheets, the Himalayas, and in other alpine regions of the world comprise very important archives because they provide extensive detailed information about past climate variability and atmospheric composition

The ratio of oxygen isotopes in ice can indicate the temperature at the time ice was deposited as snow. Air bubbles can be analysed to measure atmospheric carbon dioxide and methane concentrations at the time the bubbles were trapped in the ice.

Dust trapped in the ice may indicate windy, arid conditions. Geochemistry, including trace elements and salts, can tell a story about regional atmospheric circulation. The core from the Russian Rostock station in Antarctica provides information back to at least 160,000 years ago, and when drilling is completed a climate record of the last 500,000 years is probable.

Fossil pollen and phytoliths

Different classes of plants produce pollen grains and phytoliths (siliceous formations precipitated by plants) that have distinctive shapes. Pollen grains and phytoliths are often found preserved in sediment cores from ponds, lakes and marine environments.

Lake sediments

Composition and sedimentation rates in lakes change in response to variations in environmental conditions during periods of wet and dry climate. Pollen in the sediments can indicate the type of vegetation present, and plankton biota indicates physical and chemical conditions in the lake water. In some cases, stark seasonal changes in lake inflows and sedimentation can cause annual layers to form in lake sediments.

Annual layers, or varves, commonly form in lakes fed by glacial meltwater, and can be used to infer the amount of melted ice and what past warm season temperatures were like. Within the sediment layers, microfossils like diatoms, bugs, and plant material are preserved. These fossils can also reveal information about what past environmental conditions were like, sometimes with incredible precision.

Ocean sediment cores

These cores contain primitive shelled animals (foraminifera) whose abundance in the surface layers of the ocean depends on surface water temperature and other conditions. Off New Zealand the rate and type of sediment deposition depends on factors such as the amount of glacial activity and on other climate-driven erosion processes.

Pollen types and the isotopic composition of material in the sediments provide further information on past climates. Cores obtained off New Zealand from the international deep sea drilling project provide information as far back as 6.3 million years, and drilling of more cores is planned.

New Zealand is coordinating an interesting international drilling project near Cape Roberts in Antarctica, to establish more information about past Antarctic climate and ice extent.

Loess

Loess are fine-grained wind-blown dust deposits on land. They typically accumulate during periods characterised by dry and windy conditions. In New Zealand, they are associated with cool and cold intervals that coincide with glacial advances. Numerous loess sections can be found on the South Island, particularly in eastern regions.

Glaciers

Variations in the past size of glaciers can be inferred from the location of moraines (rocks and debris deposited by glaciers that mark a former ice margin position), outwash fans, buried soils, and by the presence of glacial features in the landscape. In New Zealand, cool summer temperatures are only one factor in promoting ice accumulation on glaciers, and snow accumulation rates also respond to changes in the strength and direction of the westerly wind flow and sea level pressure in summer.

Speleothems

Speleothems are used to describe a stalactite, stalagmite or flowstone cave deposit of crystalline nature. These deposits occur within karst terranes in subterranean caverns mainly as calcite precipitated from groundwater that percolated through overlying limestone or marble rock.

Tree rings

Tree rings are some of the best resolved records of past climate in the world. This is because, in many cases, one tree ring is grown each year, allowing tree rings to be dated with great precision and with annual resolution.

Tree growth is dependent on many factors. However, common growth patterns often emerge at the regional scale between trees, suggesting there is a common growth response to climate changes. Correlations of tree ring data with soil moisture, temperature, and precipitation often enable tree ring records to be substituted for instrumental climate data into the distant past.

In the case of NZ, which has many long lived tree species suitable for dendrochronology, long climate reconstructions of droughts, storms, and even El Nino events are possible.

Boreholes

It is sometimes possible to deduce past surface temperatures going back several hundred years by measuring the way temperature varies with depth in a borehole several hundred metres deep (at a suitable site not disturbed by groundwater flow). This is because fluctuations in ground surface temperatures propagate slowly downwards into the earth as a “temperature wave”.

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THE SUN AND OUR CLIMATE

TT

Weather Eye
with John Maunder

The NASA Solar Physics website (and other web sites such as the Royal Observatory of Belgium) includes information on the sun, sunspot numbers, the ‘Maunder Minimum', and sunspot cycle predictions.

The  sunspot index is updated monthly and available from 1749.

The last time the monthly sunspot number was above 100 for any significant period of time was September 2002 when the value was 109.6, and the last time the value was above 200 was in August 1990 when the value was 200.3.

The current sunspot number is 30.

A sunspot is a relatively dark, sharply defined region on the solar disc - marked by an umbra (dark area) which is 2000 degrees Celsius cooler than the effective photosphere temperature.

The average diameter of a sunspot is 4000 km, but can exceed 200,000 km.

The recent decline in solar activity may have been associated with the recent/current “hiatus” in the pace of “global warming” apart from the warming associated with the significant 1998 and 2015/16  El Nino events.

The maximum of Solar Cycle 24 was reached in April 2014, with a maximum of the 13-month smoothed sunspot number at 81.8. Since then, solar activity has steadily declined (the monthly mean sunspot number is now around 30).

The current Solar Cycle 24 proved to be 30% weaker than the previous solar cycle, which reached 119.7 in July 2000, and thus belongs to the category of “moderate cycles”, like cycles 12 to 15, which were the norm in the late 19th and early 20th century.

As this late maximum comes more than 5 years after the preceding minimum in December 2008, cycle 24 must have now entered its long declining phase, as none of the past observed cycles had longer delays between minimum and maximum.

Therefore, the average solar activity should progressively decrease towards a minimum around 2020.

We are currently over six years into solar cycle 24. This the smallest sunspot cycle since solar cycle 14 which had a maximum of 64.2 in February of 1906.

The “Maunder Minimum” period is named after the solar astronomer Edward Walter Maunder (1851-1928), who while working at The Royal Observatory at Greenwich discovered the dearth of sunspots during the 1650-1700 period.

Time will tell whether the sun will once again go into another “Maunder Minimum” within the lifetime of the present generation, and what affect it will have on our climate.




Tauranga Average Afternoon Temperatures: March 1913-2016


Weather Eye
with John Maunder

Temperatures have been recorded in the Tauranga area at several sites during the last 100 years including the current Tauranga Airport site from June 1990.

The graph shows details of the average daily maximum temperatures, called simply ‘afternoon', for Tauranga for the months of March from 1913-2016.

March 1947 is not included because of incomplete data.

The average daily maximum temperature for March 2016 was 23.4 degrees Celsius, 0.9 degrees Celsius milder than average.

The long-term average afternoon temperature in March for Tauranga is 22.5 degrees Celsius, ranging from the cool March months of 1960 with an average afternoon temperature of 20.4 degrees Celsius, and 1940 with an average afternoon temperature of 20.8 degrees Celsius, to the warm March months of 1916 (24.7 degrees Celsius), and 1938 and 1968 (24.6 degrees Celsius).

The graph of the average afternoon temperatures for March shows generally normal variations from March to March.

From 1913 to 2015, there have been seven March months with an average afternoon temperature of 24.0 degrees Celsius or more, and 13 March months with an average afternoon temperature of 21.5 degrees Celsius or less.

The seven warmest March months – in terms of average afternoon temperatures on record –in chronological order are: 1913, 1914,1916, 1938, 1968, 2010 and 2013.

In contrast the 13 coolest March months – in terms of afternoon temperatures on record –in chronological order are: 1923, 1934,1936, 1940, 1944, 1945, 1949, 1960, 1974, 1976, 1992, 1993 and 1998.

The average afternoon temperature for March for the 48 years from 1914-1962 was 22.4 degrees Celsius, compared with an average of 22.6 degrees Celsius for the 48 years from 1963-2011.



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Tauranga March Rainfalls 1898-2016


Weather Eye
with John Maunder

Rainfalls for the month of March have been recorded in Tauranga since 1898 – except for 1904, 1908 and 1909.

This graph below shows the range of rainfalls from a high of 504 mm in 1979, to a low of 5 mm in 1943.

The second wettest March was in 1972, when 318 mm was recorded, and two March months – 1921 and 2010 – recorded 14 mm.

The long-term average rainfall for Tauranga for March is 109 mm. The rainfall for March 2016 was 146 mm.

 

The graph shows no significant overall trend in rainfalls in March during the last 110 years, apart from a small increase in the average rainfall for the 50 years ending in 1960 of 103 mm, compared with 117 mm in the 50 years to 2010.

Since 1898, there have been eleven March months with a rainfall of 200 mm or more, and eleven March months with a rainfall of 30 mm or less.

The wettest March months in chronological order are: 1902,1918,1922,1935,1941,1944,1957,1962,1972,1979 and 1987.

The driest March months in chronological order are: 1903,1905,1921,1943,1951,1952,1953,1969, 2004, 2010 and 2013.

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The Latest WeatherEye  No 152 issued on March 29, 2016

Global Monthly Temperatures: January 1979 to February 2016


Weather Eye
with John Maunder

Professor Ole Humlum, of the Institute of Geosciences, University of Oslo, Norway, maintains a very comprehensive climate web site and much of this WeatherEye is from his website.  See http://www.climate4you.com/Text/Climate4you_February_2016.pdf

A graph of five global monthly temperatures January 1979 to January/February 2016 is shown below.

The graph shows a superimposed plot of Quality Class 1 and Quality Class 2 and Quality Class 3 global monthly temperature estimates.

As the base period differs for the different temperature estimates, they have all been normalised by comparing to the average value of 30 years from January 1979 to December 2008.

The heavy black line represents the simple running 37 month mean of the average of all temperature records.

 

The numbers shown in the lower right corner represent the temperature anomaly relative to the individual 1979-1988 averages.

It should be kept in mind that satellite and surface-based temperature estimates are derived from different types of measurements, and comparing them directly as done in the diagram above therefore may be somewhat problematical.

However, the different types of temperature estimates appear to agree quite well as to the overall temperature variations on a two-three year scale, although on a shorter time scale there are often considerable differences between the individual records.

All five global temperature estimates presently show a general overall stagnation, at least since 2002.

However, there appears to be  small increase (warming) during the last few years. The year 1998 and the current 2015/16 period was affected by the oceanographic El Nino event.

This stagnation doesn't exclude the possibility that global temperatures will begin to increase again later.

On the other hand, it also remains a possibility that Earth just now is passing a temperature peak, and global temperatures will begin to decrease during the coming years.

Time will show which of these two possibilities is correct. One of several key global temperature graphs is the monthly average surface air temperature calculated by the Goddard Institute for Space Studies, at Columbia University, New York City, USA.

The graph is updated to February 2016. GISS is a laboratory of the Earth-Sun Exploration Division of NASA's Goddard Space Flight Center and a unit of the Columbia University Earth Institute.

The thick line is the simple running 37 month average, nearly corresponding to a running 3 year average

 

The following link will take you directly to a monthly very comprehensive newsletter with global meteorological information updated to February 2016.

http://www.climate4you.com/

The website referred to above is produced by Professor Ole Humlum, of the Institute of Geosciences, University of Oslo, Norway.



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The Latest WeatherEye  No 151 issued on March 21 2016

Global Average Temperatures of the Troposphere: 1979 to February 2016


Weather Eye
with John Maunder

The latest global average temperatures of the troposphere – those observed from US National Oceanic and Atmospheric Administration satellites – are computed by the University of Alabama at Huntsville in the United States.

The above chart shows that since 1979, when reliable satellite observations became available, there has been little overall trend from the average temperatures during the 30-year period from 1981-2010 in the tropospheric temperatures, apart from a period of somewhat warmer temperatures since about 1997, and two significant warm periods associated with the El Nino events in 1998 and 2015-16.

The troposphere is the lowest layer of Earth's atmosphere.

It contains approximately 75 per cent of the atmosphere's mass and 99 per cent of its water vapour and aerosols.

The average depth of the troposphere is approximately 17 km in the middle latitudes.

The tropospheric temperature data for 2011 is January 0.0 degrees Celsius, February -0.02, March -0.10, April +0.12, May +0.14, June +0.32, July +0.38, August +0.33, September +0.29, October +0.12, November +0.12, December +0.10 degrees.

The data for 2012 is: January -0.09 degrees, February -0.12, March +0.11, April +0.29, May +0.29, June +0.37, July +0.28, August +0.34, November +0.28, December +0.20 degrees. The data for 2013 is: January +0.50 degrees, February +0.18, March +0.20, April +0.10, May +0.07, June +0.30, July +0.17, August +0,16, September +0.37, October +0.29, November +0.19, December +0.23 degrees.

The data for 2014 is: January +0.30 degrees, February +0.18, March +0.17, April +0.19, May +0.33, June +0.31, July +0.30, August +0.20, September +0.30, October +0.37, November +0.33, and December +0.33 degrees Celsius.

The data for 2015 is: January +0.20 degrees C, February +0.18 degrees C,  March +0.14 degrees C, April +0.07 degrees C, May +0.30 degrees C, June +0.32 degrees C, July +0.18 degrees C, August +0.22 degrees C, September +0.20 degrees C, October +0.32 degrees C,. November +0.40 degrees C, and December +0.48 degrees C.

The data for 2016 is: January +0.55 degrees C,  and February +0.83 degrees C.

The coolest months since 1979 were September 1984, with minus 0.49 degrees Celsius, and November 1984, with minus 0.42 degrees Celsius.

The warmest months were February 2016 with plus 0.83 degrees C, and February and April 1998, both plus 0.76 degrees Celsius.

The chart shows the El Nino warming in the 1998 period, and 2015-16 periods, and the Mount Pinatubo, volcanic cooling during 1992-1993.


Average February Afternoon Temperatures 1915-2016


Weather Eye
with John Maunder

This is the 150th issue of WeatherEye

Temperatures have been recorded in the Tauranga area at several sites during the last 100 years, including the current Tauranga Airport site from June 1990.

It's very common for areas such as Tauranga to have had different observation sites during the years; and the readings from the earlier sites have been adjusted to the present site using ‘standard climatological procedures'.

It's considered the temperature series described here is a fair and true record of what the temperature would have been if the current observation site (Tauranga Airport) had been used throughout the period.

It's important to note that in considering ‘climate change', the methodology used in computing an 'official' set of climate observations is very important – as otherwise erroneous conclusions may be drawn.

Traditionally, temperature observations have been recorded with a set of maximum and minimum temperature thermometers. These record the daily maximum temperature (usually recorded in mid-afternoon), and daily minimum temperature (usually recorded just before dawn).

This analysis of February temperatures for Tauranga is for the average daily maximum temperatures.

The graph above shows details of the average daily maximum temperatures (called simply ‘afternoon'), for Tauranga for February from 1915-2015.

The long-term average afternoon temperature in February for Tauranga is 23.8 degrees Celsius, ranging from the ‘cool' February months of 1934, with an average afternoon temperature of 21.6 degrees C , and 1921 with an average afternoon temperature of 21.8 degrees Celsius, to the ‘warm' February months of 1916 (26.4 degrees Celsius), and 1998 (26.2 degrees Celsius).

The graph of the average afternoon temperatures for February shows generally 'normal' variations from February to February.

The average afternoon February temperature for the 49 years from 1963-2011 of 24.0 degrees Celsius: this is just 0.3 degrees Celsius higher than the average afternoon February temperature for the 49 years from 1914-1962.

From 1915 to 2016, there have been six February months with an average afternoon temperature of 25.5 degrees Celsius or more, and six February months with an average afternoon temperature of 22.5 degrees Celsius or less.

The average afternoon temperature for February this year was  25.1 degrees Celsius, which was 1.3 degrees Celsius above the long term average.

The six ‘warmest' February months (in terms of afternoon temperatures) on record, in chronological order, are: 1916, 1928, 1954, 1955, 1998, and 2011.

In contrast the six ‘coolest' February months (in terms of afternoon temperatures) on record, in chronological order, are: 1921, 1931, 1934, 1940, 1976, and 2004.










Tauranga February Rainfalls - 1898-2016


Weather Eye
with John Maunder

Rainfalls for the month of February have been recorded in Tauranga since 1898 (except for 1904, 1908, and 1909).

The graph of February rainfalls in Tauranga shows the range of rainfalls from a high of 343 mm in 1936 to a low of only 7 mm in 1973.

The graph shows predominantly "normal" variations from year to year.

Nine February months have had a rainfall of less than 15 mm. Nine February months also have had a rainfall of 200 mm or more.

The wettest February was 1936 with 343 mm, and the second wettest February was 2001 when 268 mm was recorded.

The driest February month was 1973 with 7 mm, and the February months of 1942, 1987, and 2011 each had a rainfall of 8 mm.

The rainfall for February 2016 was 145 mm. The long-term February rainfall for Tauranga is 90 mm.

In chronological order, the wettest nine February months were 1920, 1933, 1934, 1936, 1938, 1960, 1966, 2001, and 2004.

In chronological order, the driest nine February months were 1942, 1970, 1972, 1973, 1987, 1999, 2000, 2010, and 2011.




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Arctic and Antarctica Sea Ice 1980-2015


Weather Eye
with John Maunder

The National Snow and Ice Data Centre, in Boulder, Colorado, has an extensive website on Arctic and Antarctic sea ice.  (see http://nsidc.org/data/seaice_)

Graphs of the extent of the Northern Hemisphere and Southern Hemisphere ice – updated to December 2015 – from the above website are shown below.

These show from 1979 to 2015 the Northern Hemisphere ice extent decreased at the rate of 3.4 per cent per decade, compared with an increase of 2.2 per cent per decade during the same period in the Southern Hemisphere.

The end of 2015 finished with the Arctic sea ice extent tracking between one and two standard deviations below average, as it did throughout the autumn.

This caps a year that saw the lowest sea ice maximum in February, and the fourth lowest minimum in September.

In Antarctica, December 2015 sea ice extent was slightly above average, but far below the exceptionally large ice extents recorded for December 2013 and 2014.

A slow-down in the rate of Antarctic sea ice growth in July was followed by near-average extents in the subsequent months

The year 2015 will be remembered for three major events in sea ice extent: the lowest Arctic maximum in the satellite record, the fourth lowest Arctic minimum in the satellite record.

From February 2013 through June 2015, Antarctic sea ice was at record or near-record daily extents.

Antarctic sea ice set consecutive record winter maxima in 2012, 2013 and 2014.

(Contrary to 2013 and 2014, autumn and spring conditions in 2012 were near-average.) But during this year's mid-winter period, Antarctic sea ice growth slowed.

Since then, extent in the Southern Hemisphere has generally been slightly above average levels for Antarctic sea ice extent after more than two years of record and near-record highs.




http://www.sunlive.co.nz/blogs/9323-arctic-and-antarctica-sea-ice-19802015.html

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Global Temperatures 1880-2015


Weather Eye
with John Maunder

Global temperatures are compiled for various areas, including global (land-ocean), global (meteorological stations), three latitude bands, and hemispheric, by the Goddard Institute for Space Studies of NASA.

A graph of the global temperatures (for the land/ocean) from 1880 to 2015, show a general warming from 1910 to the early 1940's, a cooling from the early 1940's to the mid-1970's; a general warming from the mid-1970's to about 1998; a stable period of temperatures until about the 2010, and  a warming from 2011.

 

The green bars on the graph show the uncertainty estimates at various times

The yearly global temperatures (expressed as differences from the 1951-1980 average), since 1998 are:

1998:   +0.58 degrees Celsius

1999:   +0.33 degrees Celsius

2000:   +0.35 degrees Celsius

2001:   +0.48 degrees Celsius

2002:   +0.56 degrees Celsius

2003:   +0.56 degrees Celsius

2004:   +0.49 degrees Celsius

2005:   +0.69 degrees Celsius

2006:   +0.63 degrees Celsius

2007:   +0.66 degrees Celsius

2008:   +0.53 degrees Celsius

2009:   +0.64 degrees Celsius

2010:   +0.72 degrees Celsius

2011:   +0.60 degrees Celsius

2012:   +0.63 degrees Celsius

2013:   +0.65 degrees Celsius

2014:   +0.74 degrees Celsius

2015:   +0.87 degrees Celsius



http://www.sunlive.co.nz/blogs/9289-global-temperatures-18802015.html

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http://www.sunlive.co.nz/blogs/16_regular-columnists.html/page-2

Tauranga Average January Afternoon Temperatures 1914-2016

 0 0Google +0 0
Weather Eye
with John Maunder

Temperatures have been recorded in the Tauranga area at several sites during the last 100 years, including the current Tauranga Airport site from June 1990.

 

The graph above shows details of the average daily maximum temperatures (called simply ‘afternoon') for Tauranga for January from 1914-2016.

The long-term average afternoon temperature in January for Tauranga is 23.8 degrees Celsius, ranging from the cool January months of 1920, with 21.6 degrees Celsius, and 1939 with 21.8 degrees Celsius, to the very warm January month of 1935, with 27.7 degrees Celsius, and January 1970 with 25.7 degrees Celsius.

The average afternoon temperature in January 2016 was 24.1 degrees Celsius.

The graph of the average afternoon temperatures for January shows generally normal variations from January to January during the last 100 years.

The average January afternoon temperature during the 50 years from 1963 to 2011 of 23.8 degrees Celsius, is the same average recorded in the 50 year period from 1914 to 1962.

From 1914 to 2015, there have been seven January months with an average afternoon temperature of 25.4 degrees Celsius or higher, and seven January months with an average afternoon temperature of 22.5 degrees Celsius or lower.

The seventh-warmest January months (in terms of afternoon temperatures), on record, in chronological order, are 1915, 1935, 1970, 1957, 1999, 2009 and 2015.


Tauranga January Rainfalls 1898-2016


Weather Eye
with John Maunder

The graph shows the range of Tauranga's January rainfalls from 1898-2015, varied from an extreme high of 532 mm in 1907 to a low of only 1 mm in 1928.

The second wettest January was 2011, when 347 mm was recorded; and the second driest January was in 2013, when only 4 mm fell.

The long-term average rainfall for Tauranga for January is 89 mm.

The rainfall for January 2016 was 104 mm. The graph of the January rainfall shows generally normal variations from year to year.

Since 1898 there have been eight January months with a rainfall of 180 mm or more, with two such wet January months, 1940 and 1941, being consecutive.

Fourteen January months have experienced rainfalls of less than 20 mm, with two such dry January months, 1978 and 1979, being consecutive.

In chronological order, the eighth wettest January months are 1907 with 532 mm, 1920 with 196 mm, 1940 with 254 mm, 1941 with 245 mm, 1951 with 204 mm, 1965 with 183 mm, 1989 with 268 mm, and 2011 with 347 mm.

In contrast, the sixth driest January months in chronological order are 1900 with 8 mm, 1928 with 1 mm, 1944 with 10 mm, 1957 with 8 mm, 1988 with 9 mm,  2013 with 4 mm, and 2015 with 8 mm

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http://www.sunlive.co.nz/blogs/9199-groundhog-day-february-2-those-climate-predictions.html

Groundhog Day February 2... Those Climate Predictions


Weather Eye
with John Maunder

Groundhog Day, February 2, is a popular tradition in the United States. It is also a legend that traverses many centuries, its origins clouded in the mists of time with ethnic cultures and animals awakening on specific dates.

Myths such as this tie our present to the distant past, when nature did indeed influence our lives –and to many, nature is still influencing out lives. It is also the day the Groundhog comes out of his hole after a long winter sleep to look for his shadow.

Tradition has it if the groundhog sees his shadow, he regards it as an omen of six more weeks of bad weather and returns to his hole. But, if the day is cloudy and, hence, shadow less, he takes it as a sign of spring and stays above ground.

The groundhog tradition stems from similar beliefs associated with Candlemas Day and the days of early Christians in Europe. It marked a milestone in the winter and the weather that day was important. And according to an old English Song:

“If Candlemas be fair and bright,

Come, winter, have another flight;

If Candlemas brings clouds and rain,

Go winter, and come not again.”

The Roman legions, supposedly brought this tradition to the Teutons, or Germans, who picked it up and concluded that if the sun made an appearance on Candlemas Day, an animal, the hedgehog, would cast a shadow; thus predicting six more weeks of bad weather, which they interpolated as the length of the ‘Second Winter'.

In the United States, Pennsylvania's earliest settlers were Germans and they found groundhogs in profusion in many parts of the State. They determined the groundhog, resembling the European hedgehog, was a most intelligent and sensible animal; and therefore decided if the sun did appear on February 2nd, this wise animal would see its shadow and hurry back into its underground home for another six weeks of winter.

The Germans thus recited:

“For as the sun shines on Candlemas Day,

So far will the snow swirl until the May”.

This passage may be the one most closely-represented by the first Punxsutawney Groundhog Day observances because there were references to the length of shadows in early Groundhog Day predictions. The ancient Candlemas legend and similar belief continue to be recognised annually on February 2, due to the efforts of the Punxsutawney Groundhog Club.

Early observances of Phil's (the Groundhog) predictions were conducted privately in the wooded areas around the town. Today, the celebration today sees thousands of visitors from worldwide as revellers await Phil's appearance with national-wide TV coverage.

The ‘Punxsutawney Spirit' newspaper is credited with printing the news of the first observance in 1886.

“Today is groundhog day, and up to the time of going to press the beast has not seen his shadow.”

In 1993, Columbia Pictures released the movie Groundhog Day starring Bill Murray. In the years following the release of the movie, record crowds numbering as high as 30,000 have visited Gobbler's Knob in Punxsutawney.

Punxsutawney Phil gets his longevity from drinking “groundhog punch”. One sip, which is administered every summer at the Groundhog Picnic, gives him seven more years of life.

Contrary to media explanations , Phil's forecasts are not made in advance by the Inner Circle. Indeed, only after Phil emerges from his burrow on February 2 does he  speaks to the Groundhog Club President in “Groundhog Language”. Phil's proclamation is then translated for the world to hear.

The US National Weather Service notes that the Punxsutawney Groundhog Day predictions have been right 10 times and wrong 15 times since 1988. They comment that “Unfortunately ,the famous groundhog has shown no talent for predicting the arrival of spring, especially in recent years, and  Phil's competitor groundhogs across the Nation fared no better.”

However, it is a great story.

Tauranga Annual Average Afternoon Temperatures 1914-2015



Weather Eye
with John Maunder

Temperatures have been recorded in the Tauranga area at several sites in the last 100 years, including the current Tauranga Airport site from June 1990.

The graph below shows details of the average annual daily maximum temperatures (called simply 'afternoon'), for Tauranga for the years 1914-2015.

The long-term average afternoon temperatures for Tauranga for a calendar year is 18.6 degrees Celsius, including the cool years of 18.1 degrees Celsius in 1976, 18.1 degrees Celsius in 1992, 18.2 degrees Celsius in 1923, and 18.3 degrees Celsius in 1918.

In contrast, Tauranga's warmest years (in terms of the average afternoon temperature) are: 20.2 degrees Celsius in 2013, 20.1 degrees Celsius in 1916, 20.0 degrees Celsius in 1998, and 19.9 degrees Celsius in 2010.

The average afternoon temperature in 2015 was 19.6 degrees Celsius.

Since 1914, there have been twelve calendar years with an average afternoon temperature of 19.5 degrees Celsius or more. In chronological order these years are: 1914, 1915, 1916, 1928, 1998, 1999, 2005, 2010, 2011, 2013, 2014, and 2015.

In comparison, there have been 11 calendar years with an average afternoon temperature of 18.5 degrees Celsius or less. In chronological order these years are: 1918, 1920, 1923, 1941, 1945, 1965, 1976, 1977, 1980, 1991, and 1992.

The graph of the average afternoon temperatures for the years 1914-2014 shows generally normal variations from year to year from 1915 to the mid-1990's, followed by several years of above-average temperatures, including the last recent five “warm” years: 2010, 2011, 2013, 2014, and 2015.

The annual average afternoon temperature shows a warming of about 0.8 degrees Celsius during the 51 years from 1963-2013 from 19.0  degrees Celsius, compared with 18.2 degrees Celsius during the 49 years from 1914-1962.




Tauranga Average Afternoon December Temperatures 1913-2015


Weather Eye
with John Maunder

Temperatures have been recorded in the Tauranga area at several sites during the last 100 years, including the current Tauranga Airport site from June 1990.

The graph below shows details of the average daily maximum temperatures, called simply ‘afternoon', for Tauranga for December from 1913-2015.

The long-term average afternoon temperature in December for Tauranga is 22.1 degrees Celsius, ranging from the ‘cool' December months of 2004 (20.1), 1968 (20.5) and 1944 and 1951 (both 20.7), to the ‘warm' December months of 1940 (24.4), 1937 (24.0), and 1990 (23.8).

The graph of the average afternoon temperatures for December shows generally normal variations from December-to-December during the last 100 years.

The average December afternoon temperature during the 50 years from 1963 to 2011 of 22.2 degrees Celsius is the same as recorded in the 50 years from 1914 to 1961.

The average afternoon temperature in December 2015 was 22.9 degrees C.

From 1913 to 2015, there have been 21 December months with an average afternoon temperature of 23.0 degrees C or more, and 12 December months with an average afternoon temperature of less than 21.0 degrees C or less.

The seven warmest December months (in terms of afternoon temperatures), on record, in chronological order, are 1934, 1937, 1940, 1953, 1990, 1993, and 1994.

By contrast, the seven coolest December months (in terms of afternoon temperatures), on record, in chronological order, are 1921, 1946, 1951, 1962, 1968, 1977, and 2004.



Tauranga Annual Rainfalls 1898-2015


Weather Eye
with John Maunder

 Monthly rainfalls for Tauranga have been recorded at several recording sites during the last 117 years.

The rainfall for 2015 of  842 mm was the third (equal) lowest rainfall on record.

From January 1898 to December 1904, the observation site was described as the Tauranga Harbour; from November 1904 to April 1907 the site was described as simply ‘Tauranga'.

From January 1910 to December 1923 the site was Waikareao, in Otumoetai; from January 1924 to September 1940 the site was at 148 Waihi Rd, in Judea; from October 1940 to January 1941 the site was at Te Puna; and from February 1941 to now, the site is Tauranga Airport.

The methodology use in adjusting the older sites to the current observing site is published in the ‘NZ Meteorological Service Miscellaneous Publication' No 180 in 1984.

It is considered that the homogeneous rainfall series described here is a fair and true record of what the rainfall would have been if the current observation site (Tauranga Airport) had been used since 1898.

This should be coupled with the understanding that although standard accepted methodologies have been used, any adjustments are only estimates of what would have occurred if the location of the rainfall records had always been in the same place with the same surroundings and the same or similar recording gauge.

In terms of climate change (such as is it getting wetter or drier, or warmer or colder), the methodology used in computing an ‘official' set of climate observations is very important, as otherwise erroneous conclusions may be drawn.

The long-term average rainfall for Tauranga for the calendar year is 1300 mm, ranging from a low of 747 mm in 2002, to a high of 2049 mm in 1962.

For comparison, the rainfall for the last year, 2015, was 842 mm.

Since 1898, there have been only five years with a rainfall of less than 900 mm, they are 1914, 1982, 1993, 2002, and 2015.

And there's only been four years with a rainfall of more than 1800 mm; they are the two consecutive years of 1916 and 1917, plus 1938 and 1962.

The ten wettest years on record are: 1962 which had 2049 mm or 57 per cent above of the long-term average, while 1917 had 1985 mm or 52 per cent above average.

Also, 1916 had 1941 mm or 49 per cent above average, plus 1938 (1817 mm), 1920 (1789 mm), 1956 (1777 mm), 1979 (1730 mm), 2011 (1696 mm), 2005 (1682 mm), and 1935 (1670 mm).

In chronological order, these wettest years occurred in 1916, 1917, 1920, 1935, 1938, 1956, 1962, 1979, 2005, and 2011.

In contrast, the ten driest years on record are: 2002 (747 mm or 48 per cent below the long-term average), 1914 (773 mm or 41 per cent below the long-term average), 1982 (842 mm or 36 per cent below the long-term average), 2015 (842 mm or 36 per cent below the long term average), plus 1993 (863 mm), 1906 (950 mm), 1919 (962 mm), 1997 (978 mm), 1973 (989 mm), and 1986 (991 mm).

In chronological order, these driest years occurred in 1906, 1914, 1919, 1973, 1982, 1986, 1993, 1997, 1999, and 2015.

The average rainfall in Tauranga for the 50 years 1911-60 was 1365 mm, compared with the average rainfall for the 50 years 1961-2010  of 1263 mm.


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Tauranga December Rainfalls 1898-2015


Weather Eye
with John Maunder

The second wettest December was 2011, when 276 mm was recorded; and the second driest December was in 1994, when only 14 mm fell.

The graph below shows the range of Tauranga's December rainfalls, from an extreme high of 447 mm in 1962 to a low of only 4 mm in 1930.

The rainfall for December 2015 of 18 mm was the fourth lowest on record.

The long-term average rainfall for Tauranga for December is 100 mm. The rainfall for December 2015 was 18 mm which made it the fourth driest December on record.

The graph of the December rainfall shows, at first glance, normal variations from year to year.

However, there has been a notable increase in December rainfalls during the last few decades. Indeed, the average December rainfall in Tauranga for the 50-year period from 1961-2010 of 109 mm, is 20 per cent higher than the rainfall for the 50-year period 1911-1960.

Since 1898, there have been eight Decembers with a rainfall of 200 mm or more, five of which occurred during the period 1962 to 2011.

Seven December months have experienced rainfalls of 30 mm or less. Of significance are the high rainfalls in the consecutive December months of 1962 and 1963, of 447 mm and 224 mm respectively.

In chronological order, the eighth-wettest Decembers are 1924 with 225 mm, 1928 with 227 mm, 1936 with 240 mm, 1962 with 447 mm, 1963 with 224 mm, 1996 with 241 mm, 2001 with 208 mm and 2011 with 276 mm.

In contrast, the eighth-driest December months in chronological order are 1902 with 27 mm, 1912 with 22 mm, 1919 with 22 mm, 1930 with 4 mm, 1986 with 30 mm, 1990 with 21 mm, 1994 with 14 mm, and 2015 with 18 mm .





In the Bleak Mid-Winter


Weather Eye
with John Maunder

In the bleak mid-winter,

Frosty wind made moan,

Earth stood hard as iron,

Water like a stone,

Snow had fallen,

Snow on snow,

Snow on snow,

In the bleak mid-winter,

Long ago.

These words, from the first verse of the well-known carol, were written by the English poet Christina Rossetti in 1872 in response to a request from the magazine ‘Scribner's Monthly' for a Christmas poem.

It was published posthumously in Rossetti's ‘Poetic Works' in 1904. The poem became a Christmas carol after it appeared in ‘The English Hymnal' in 1906. The text of this Christmas poem has been set to music many times; the most famous settings being composed by Gustav Holst and Harold Edwin Darke in the early 20th Century.

The version by Darke is favoured by cathedral choirs, and is the one usually heard performed on the radio broadcasts of ‘Nine Lessons and Carols' by the King's College choir.

The carol featured in the Queen's Christmas TV  message a few year ago

Of some significance is that two years ago on December 15, 2013 the ‘Mail Online' (UK) had the following headlines relating to a severe snow storm, which hit the Holy City  – and at the same time Cairo experienced its first snowfall in more than 100 years. Perhaps a reminder that Christmas carols  do come alive?

A Christmas card come to Life: Jerusalem hit by worst snowstorm for 20 years, as eight inches fall across Holy City.

- Unusually heavy snowfall, as temperatures dip below freezing.
- Dome of the Rock and Western Wall bathed in white blanket.
- Prime Minister Natanyahu gets in on the fun with family snowball fight.

As all my readers will be aware, the weather is always with us; and although we may all hope that the weather this Christmas and in 2016  will be to our liking, it is perhaps important to remember that in the Southern Hemisphere where the carol ‘In the Bleak Mid-Winter' may seem unusual, there have been two significant and tragic events.

The first was on Christmas Eve in New Zealand, in 1953, when the Tangiwai rail disaster occurred with loss of 151 lives. The second was in Darwin, in Australia on Christmas Day 1974, when Tropical Cyclone Tracy killed 71 people and destroyed 80 per cent of the city's houses.

I take this opportunity of wishing all my readers a very happy Christmas and I will be back in 2016 with some more WeatherEyes.

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Tauranga November Average Afternoon Temperatures 1913-2015

 
Weather Eye
with John Maunder

During November 2013, Tauranga had its warmest November ( average afternoon temperature of 22.3 degrees Celsius), since records began in 1913. Since then the November temperatures have been 20.5 degrees Celsius in 2014, and 20.7 degrees Celsius in 2015.

Temperatures have been recorded in the Tauranga area at several sites in the last 100 years, including the current Tauranga Airport site from June 1990.

The graph shows details of the average daily maximum temperatures (called simply ‘afternoon') for Tauranga for Novembers from 1913-2015.

The long-term average afternoon temperature in November for Tauranga is 20.1 degrees Celsius, ranging from the cool November months of 1976 (18.4 degrees Celsius), and 1941 (18.5 degrees Celsius), to the warm November months of 2013 (22.3 degrees Celsius), and 1954 (22 degrees Celsius).

The graph of the average afternoon temperatures for November shows generally normal variations from November to November during the last 100 years, but of note are the three warm Novembers in the years 2009, 2010, 2011, and 2013.

The average November afternoon temperature during the 50 years from 1963 to 2011 of 20.1 degrees Celsius, is nearly the same as the 20 degrees Celsius recorded in the 50 years 1914 to 1961.

From 1913 to 2013, there have been 15 November months with an average afternoon temperature of 21 degrees Celsius or more, and seven November months with an average afternoon temperature of less than 19.0 degrees Celsius.

The seventh warmest November months (in terms of afternoon temperatures), on record, in chronological order, are 1945, 1954, 1961, 1982, 2010, 2011, and 2013.

By contrast, the seventh coolest November months (in terms of afternoon temperatures), on record, in chronological order, are 1918, 1930, 1946, 1968, 1976, 1991, and 1985.

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http://www.sunlive.co.nz/blogs/9032-tauranga-november-rainfalls-18982015.html

Tauranga November Rainfalls 1898-2015


Weather Eye
with John Maunder

The graph shows the range of November rainfalls from 1898 to 2015 in Tauranga, from an extreme high of 285 mm in 1916 to a low of only 12 mm in 2009.

The second wettest November was 1967, when 240 mm was recorded; the second driest November was in 2011, when only 13 mm fell. The long-term average rainfall for Tauranga in the month of November is 85 mm. The rainfall for November 2015 of 88 mm was the wettest November since 2001.

The graph of the November rainfall shows at first glance normal variations from year to year. However, there has been a notable decrease in the November rainfalls during the last few years. Indeed, the average November rainfall in Tauranga for the 50-year period from 1961-2010 of 78 mm is only 85 per cent of the rainfall for the 50-year period 1910-1960.

Since 1898, there have been 11 November months with a rainfall of 150 mm or more (seven of which occurred during the period 1913-1952). In chronological order, the wettest Novembers are: 1913 with 205 mm, 1916 with 285 mm, 1925 with 167 mm, 1933 with 152 mm, 1936 with 153 mm, 1938 with 174 mm, 1952 with 232 mm, 1967 with 240 mm, 1981 with 191 mm, 1995 with 204 mm, and 1999 with 160 mm.

In terms of dry Novembers, there have been 13 months with rainfall of 30 mm of less, four of which have occurred since 1997. In chronological order the driest Novembers are 1901 14 mm, 1902 26 mm, 1914 with 17 mm, 1919 with 23 mm, 1928 with 28 mm, 1945 with 20 mm, 1963 with 30 mm, 1982 with 24 mm, 1984 with 19 mm, 1997 with 24 mm, 2009 with 12 mm, 2011 with 13 mm, and 2012 with 27 mm.



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The Southern Oscillation Index (SOI)


Weather Eye
with John Maunder

The Southern Oscillation Index (SOI) is a standardized index based on the observed sea level pressure differences between Tahiti and Darwin, Australia. The SOI is a leading measure of the large-scale fluctuations in air pressure occurring between the western and eastern tropical Pacific (i.e., the state of the Southern Oscillation) during El Niño and La Niña episodes. In general, smoothed time series of the SOI correspond very well with changes in ocean temperatures across the eastern tropical Pacific.
 
The negative phase of the SOI represents below-normal air pressure at Tahiti and above-normal air pressure at Darwin.
 
The positive phase of the SOI represents above-normal air pressure at Tahiti and below-normal air pressure at Darwin.
 
Prolonged periods of negative SOI values coincide with abnormally warm  ocean waters across the eastern tropical Pacific typical of El Niño episodes.
 
In contrast, prolonged periods of positive SOI values coincide with abnormally cold ocean waters across the eastern tropical Pacific typical of La Niña episodes.
 
Sustained negative values of the SOI below −8 often indicate El Niño episodes. These negative values are usually accompanied by sustained warming of the central and eastern tropical Pacific Ocean, a decrease in the strength of the Pacific Trade Winds.
Sustained positive values of the SOI above +8 are typical of a La Niña episode. They are associated with stronger Pacific trade winds and warmer sea temperatures to the north of Australia. Waters in the central and eastern tropical Pacific Ocean become cooler during this time.

The graph below shows monthly values of the SOI in recent years updated to October 2015. As shown we are currently in a significant El Nino episode..

Source : Bureau of Meteorology, Australia

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Atmospheric Carbon Dioxide


Weather Eye
with John Maunder

Carbon dioxide is a colourless, odourless gas vital to life on Earth. This naturally occurring chemical compound is composed of a carbon atom covalently double bonded to two oxygen atoms. Carbon dioxide exists in the Earth's atmosphere as a trace gas at a concentration of about 0.04 per cent (400 ppm) by volume. Natural sources include volcanoes, hot springs and geysers and it is freed from carbonate rocks by dissolution in water and acids. Since carbon dioxide is soluble in water, it occurs naturally in groundwater, rivers and lakes, in ice caps and glaciers and in seawater. It is present in deposits of petroleum and natural gas.

Atmospheric carbon dioxide is the primary source of carbon in life on Earth and its concentration in Earth's pre-industrial atmosphere since late in the Precambrian was regulated by photosynthetic organisms and geological phenomena. As part of the carbon cycle, plants, algae, and cyanobacteria use light energy to photosynthesize carbohydrate from carbon dioxide and water, with oxygen produced as a waste product. Carbon dioxide is produced by plants during respiration.

Carbon dioxide is a product of respiration of all aerobic organisms. It is returned to water via the gills of fish and to the air via the lungs of air-breathing land animals, including humans. Carbon dioxide is produced during the processes of decay of organic materials and the fermentation of sugars in bread, beer and winemaking. It is produced by combustion of wood, carbohydrates and fossil fuels such as coal, peat, petroleum and natural gas.

Carbon dioxide is an important greenhouse gas. Burning of carbon-based fuels since the industrial revolution has rapidly increased its concentration in the atmosphere. It is also a major cause of ocean acidification since it dissolves in water to form carbonic acid.

Source: Wikipedia

The annual mean growth of Carbon Dioxide at the Mauna Loa Observatory in Hawaii is shown in the following chart.

 

The graph show the annual mean carbon dioxide growth rates for the Mauna Loa observatory in Hawaii. In the graph, decadal averages of the growth rate are also plotted, as horizontal lines for 1960 through 1969, 1970 through 1979, and so on.

The annual mean rate of growth of carbon dioxide in a given year is the difference in concentration between the end of December and the start of January of that year. If used as an average for the globe, it would represent the sum of all carbon dioxide added to, and removed from, the atmosphere during the year by human activities and by natural processes. There is a small amount of month-to-month variability in the carbon dioxide concentration that may be caused by anomalies of the winds or weather systems arriving at Mauna Loa.

Source: NOAA


Tauranga October Average Afternoon Temperatures: 1913-2015

 
Weather Eye
with John Maunder

October 2013 had its warmest October (20.3 degrees Celsius) , since records began in 1913. Since then afternoon temperatures in October 2014 and October 2015 have been 18.3 and 19.4 degrees Celsius.

Temperatures have been recorded in the Tauranga area at several sites in the last 100 years, including the current Tauranga Airport site from June 1990.

The graph shows details of the average daily maximum temperatures (called simply ‘afternoon') for Tauranga for October from 1913-2015.

 

The long-term average afternoon temperature in October for Tauranga is 18.1 degrees Celsius, ranging from the cool October months of 1964 (15.7 degrees Celsius), and 1992 (16.5 degrees Celsius), to the warm October months of 2013 (20.3 degrees Celsius), and 1915 (19.9 degrees Celsius).

The graph of the average afternoon temperatures for October shows generally normal variations from October to October during the last 100 years.

The average October afternoon temperatures during the 50 years from 1963-2011 of 18.0 degrees Celsius is slightly cooler than the 18.3 degrees Celsius recorded in the 50 years from 1914-1961.

From 1913 to 2013, there have been thirteen October months with an average afternoon temperature of  19.0 degrees Celsius or more; and eight October months have had an average afternoon temperature of 17.0 degrees Celsius or less.

The five warmest October months (in terms of afternoon temperatures), on record, in chronological order, are 2013, 1913, 1915, 1940,  and 2015.

By contrast, the fifth coolest October months (in terms of afternoon temperatures), on record, in chronological order, are 1941, 1964, 1978, 1982, and 1992.



Tauranga October Rainfalls 1898-2015


Weather Eye
with John Maunder

The graph below shows the range of Tauranga's October rainfalls, from an extreme high of 357 mm in 1916 to a low of only 7 mm in 1984.

The second wettest October was 1928, when 269 mm was recorded; and the second driest October was in 1928, when only 11 mm fell. The long-term average rainfall for Tauranga in the month of October is 110 mm. The rainfall in October 2015 was 27 mm, the eleventh lowest October rainfall.

The graph of the October rainfall shows at first glance normal variations from year to year. However, there has been a notable decrease in the October rainfalls during the last few years.

Indeed, the average October rainfall in Tauranga during the 50-year period from 1961-2010 of 88 mm, is only 70 per cent of the rainfall for the 50-year period 1910-1960.

Since 1898, there have been 11 October months with a rainfall of 200 mm or more (10 of which occurred during the period 1900-1958), and only one October month since then has recorded this much. Ten October months have also experienced rainfalls of 25 mm or less.

In chronological order the eleven wettest October months are 1900, 1905, 1916, 1918, 1921, 1926, 1928, 1941, 1952, 1958, and 1983.  In contrast the eleventh driest October months are 1906, 1938, 1963, 1965, 1969, 1973, 1984, 1993, 2010, 2013, and 2015.



Global Monthly Temperatures January 1979 to September 2015


Weather Eye
with John Maunder

A graph of five global monthly temperatures January 1979 to September is shown below.

A superimposed plot of Quality Class 1 and Quality Class 2 and Quality Class 3 global monthly temperature estimates. As the base period differs for the different temperature estimates, they have all been normalised by comparing to the average value of 30 years from January 1979 to December 2008. The heavy black line represents the simple running 37 month mean of the average of all temperature records.

As the base period for the individual temperature estimates varies, they have all been normalised by comparing with the average value of the initial 120 months – or 10 years – from January 1979 to December 1988.

The heavy black line represents the simple running 37-month average of the average of all five temperature records.

The numbers shown in the lower right corner represent the temperature anomaly relative to the individual 1979-1988 averages.

It should be kept in mind that satellite and surface-based temperature estimates are derived from different types of measurements, and comparing them directly as done in the diagram above therefore may be somewhat problematical.

However, the different types of temperature estimates appear to agree quite well as to the overall temperature variations on a two-three year scale. Although, on a shorter time scale there are often considerable differences between the individual records.

All five global temperature estimates presently show a general overall stagnation, at least since 2002. However, there appears to be  small increase (warming) during the last few years. The year 1998 was affected by the oceanographic El Nino event.

This stagnation doesn't exclude the possibility that global temperatures will begin to increase again later.

On the other hand, it also remains a possibility that Earth just now is passing a temperature peak, and global temperatures will begin to decrease during the coming years.

Time will show which of these two possibilities is correct.

One of several key global temperature graphs is the monthly average surface air temperature calculated by the Goddard Institute for Space Studies, at Columbia University, New York City, USA. The graph is updated to September 2015. GISS is a laboratory of the Earth-Sun Exploration Division of NASA's Goddard Space Flight Center and a unit of the Columbia University Earth Institute. The thick line is the simple running 37 month average, nearly corresponding to a running 3 year average

The following link will take you directly to a monthly very comprehensive newsletter with global meteorological information updated to September 2015.

http://www.climate4you.com/

The website referred to above is produced by Professor Ole Humlum, of the Institute of Geosciences, University of Oslo, Norway.


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Global Average Temperatures of the Troposphere 1979 to September 2015


Weather Eye
with John Maunder

The latest global average temperatures of the troposphere – those observed from National Oceanic and Atmospheric Administration satellites – are computed by the University of Alabama at Huntsville in the United States.

The above chart shows that since 1979, when reliable satellite observations became available, there has been little overall trend, from the average temperatures during the 30-year period from 1981-2010 in the tropospheric temperatures, apart from a period of warmer temperatures since about 1997.

Of significance, the observations shows there is has been very little change in the overall global tropospheric temperatures during the last 18 years since 1997.

The troposphere is the lowest layer of Earth's atmosphere. It contains approximately 75 per cent of the atmosphere's mass and 99 per cent of its water vapour and aerosols. The average depth of the troposphere is approximately 17 km in the middle latitudes.

The tropospheric temperature data for 2011 is January 0.0 degrees Celsius, February -0.02, March -0.10, April +0.12, May +0.14, June +0.32, July +0.38, August +0.33, September +0.29, October +0.12, November +0.12, December +0.10 degrees.

The data for 2012 is: January -0.09 degrees, February -0.12, March +0.11, April +0.29, May +0.29, June +0.37, July +0.28, August +0.34, November +0.28, December +0.20 degrees.

The data for 2013 is: January +0.50 degrees, February +0.18, March +0.20, April +0.10, May +0.07, June +0.30, July +0.17, August +0,16, September +0.37, October +0.29, November +0.19, December +0.23 degrees.

The data for 2014 is: January +0.30 degrees, February +0.18, March +0.17, April +0.19, May +0.33, June +0.31, July +0.30, August +0.20, September +0.30, October +0.37, November +0.33, and December +0.33 degrees Celsius.

The data for 2015 is: January +0.20 degrees C, February +0.18 degrees C,  March +0.14 degrees C, April +0.07 degrees C, May  +0.30 degrees C,  June +0.32 degrees C, July +0.18 degrees C,  August +0.20 degrees C, and September +0.25 degrees C as shown on the chart..

The coolest months since 1979 were September 1984, with minus 0.49 degrees Celsius, and November 1984, with minus 0.42 degrees Celsius.

The warmest months were February and April 1998, both plus 0.76 degrees Celsius.

The chart shows the El Nino warming in the 1998 period, and the Mount Pinatubo, volcanic, cooling during 1992-1993.

For further information on weather and climate matters see: https://sites.google.com/site/johnmaunder/thesunpaysnoheedtohumancommitteespage%27st

Tauranga September Average Afternoon Temperatures: 1913-2015


Weather Eye
with John Maunder

Temperatures have been recorded in the Tauranga area at several sites in the last 100 years, including the current Tauranga Airport site from June 1990.


The graph shows details of the average daily maximum temperatures (simply called “afternoon”) for Tauranga for September from 1913-2015.

The long-term average afternoon temperature in September for Tauranga is 16.6 degrees C, ranging from the “cool” September months of 1964 (14.8 degrees C), and 1977 (14.9 degrees C), to the “warm” September months of 1915 (18.4 degrees C), and 18.3 degrees in 1914. The afternoon temperature for 2015 was 16.1 degrees C, which made it the coolest September for 11 years, and the second coolest September since 1997.

The graph of the average afternoon temperatures for September shows generally "normal" variations from September to September during the last 100 years, but five of the warmest six September months occurred from 1913 to 1921.

From 1913 to 2015, there have been ten September months with an average afternoon temperature of 17.5 degrees C or more, and eight September months with an average afternoon temperature of less than 15.4 degrees C.

The tenth “warmest” September months (in terms of afternoon temperatures) on record, in chronological order, are 1913, 1914, 1915, 1916, 1921, 1926, 1940, 2006, 2009 and 2014. By contrast, the eighth “coolest” September months (in terms of afternoon temperatures) on record, in chronological order, are 1935, 1964, 1967, 1977, 1992, 1993, 1994 and 1997.

The average afternoon temperature during September for the period 1914-62 was 16.6 degrees, compared with 16.5 degrees from 1963-2011.





Tauranga September Rainfalls 1898-2015


Weather Eye
with John Maunder

Rainfall for the month of September have been recorded in Tauranga since 1898, except for 1904, 1907, 1908, and 1909.

The graph below shows the range of rainfalls from an extreme high of 274 mm in 1973 to a low of only 16 mm in 1965.

The second wettest September was in 1900, when 256 mm was recorded, and the second driest September was in 1944, when only 27 mm fell. The long-term average rainfall for Tauranga for September is 105 mm.

The graph of the September rainfall shows normal variations from year to year.

Since 1898, there have been five Septembers with a rainfall of 200 mm or more (four of which occurred during the period 1900 to 1928, but there's only been one since then), compared with six September months with a rainfalls of 40 mm or less.

The rainfall for September 2015 was  92 mm.

In chronological order, the ten wettest September months (rainfalls over 180 mm)  are 1900,1912,1919,1923,1928,1946,1960,1969,1971 and 1973.

In contrast the eleven driest September months (rainfalls of 50 mm or less) are 1910, 1913, 1914, 1921, 1922, 1944, 1965, 1993, 1987, 2006 and 2011.

The average rainfall for Tauranga for September for the 50 years 1961-2010 of 103 mm is similar to the rainfall for the previous 50 years (1910-1960).


What are El Niño and La Niña?


Weather Eye
with John Maunder

El Niño and La Niña are complex weather patterns resulting from variations in ocean temperatures in the Equatorial Pacific.

El Niño and La Niña are opposite phases of what is known as the El Niño-Southern Oscillation (ENSO) cycle.

La Niña is sometimes referred to as the cold phase of the ENSO cycle, and El Niño as the warm phase of ENSO. These deviations from normal surface temperatures can have large-scale impacts not only on ocean processes, but also on global weather and climate.

El Niño and La Niña episodes typically last nine to 12 months, but some prolonged events may last for years. While their frequency can be quite irregular, El Niño and La Niña events occur on average every two to seven years. Typically, El Niño occurs more frequently than La Niña.

El Niño

El Niño means The Little Boy, or Christ Child in Spanish. El Niño was originally recognized by fishermen off the coast of South America in the 1600's, with the appearance of unusually warm water in the Pacific Ocean. The name was chosen based on the time of year (around December) during which these warm waters events tended to occur.

The term El Niño refers to the large-scale ocean-atmosphere climate interaction linked to a periodic warming in sea surface temperatures across the central and east-central Equatorial Pacific.

The presence of El Niño can significantly influence weather patterns, ocean conditions, and marine fisheries across large portions of the globe for an extended period of time.


A typical El Nino weather pattern (Source NIWA)

La Niña

La Niña means The Little Girl in Spanish. La Niña is also sometimes called El Viejo, anti-El Niño, or simply "a cold event."

La Niña episodes represent periods of below-average sea surface temperatures across the east-central Equatorial Pacific. Global climate La Niña impacts tend to be opposite those of El Niño impacts. In the tropics, ocean temperature variations in La Niña also tend to be opposite those of El Niño.


A typical La Nina weather pattern (source NIWA)

El Nino and La Nina weather affects over New Zealand (source Niwa)

During El Niño, New Zealand tends to experience stronger or more frequent winds from the west in summer, typically leading to drought in east coast areas and more rain in the west. In winter, the winds tend to be more from the south, bringing colder conditions to both the land and the surrounding ocean. In spring and autumn south–westerly winds are more common.

La Niña events have different impacts on New Zealand's climate. More north–easterly winds are characteristic, which tend to bring moist, rainy conditions to the north–east of the North Island, and reduced rainfall to the south and south–west of the South Island. Therefore, some areas, such as central Otago and South Canterbury, can experience drought in both El Niño and La Niña. Warmer than normal temperatures typically occur over much of the country during La Niña, although there are regional and seasonal exceptions.

Although ENSO events have an important influence on New Zealand's climate, it accounts for less than 25% of the year to year variance in seasonal rainfall and temperature at most New Zealand measurement sites. East coast droughts may be common during El Niño events, but they can also happen in non El Niño years (for example, the severe 1988–89 drought). Also, serious east coast droughts do not occur in every El Niño. However, the probabilities of the climate variations discussed above happening in association with ENSO events are sufficient to warrant management actions and planning to be taken when an El Niño or La Niña is expected or in progress.


Solar Activity and the Earth’s Climate


Weather Eye
with John Maunder

A sunspot is a relatively dark, sharply defined region on the solar disc - marked by an umbra (dark area) which is 2000 degrees Celsius cooler than the effective photosphere temperature. The average diameter of a sunspot is 4000 km, but can exceed 200,000 km.

The NASA Solar Physics website ( and other web sites such as the Royal Observatory of Belgium) includes information on sunspot numbers, the ‘Maunder Minimum', and sunspot cycle predictions. The  sunspot index is updated monthly and available from 1749. The last time the monthly sunspot number was above 100 for any significant period of time was September 2002 when the value was 109.6, and the last time the value was above 200 was in August 1990 when the value was 200.3.

The recent decline in solar activity may have helped cause the recent/current “hiatus” in the pace of “global warming”.
The maximum of solar cycle 24 was reached in April 2014, with a maximum of the 13-month smoothed sunspot number at 81.8. Since then, solar activity has steadily declined (the monthly mean sunspot number is now around 50).

Therefore, solar cycle 24 proved to be 30% weaker than the previous solar cycle, which reached 119.7 in July 2000, and thus belongs to the category of moderate cycles, like cycles 12 to 15, which were the norm in the late 19th and early 20th century.

As this late maximum comes more than 5 years after the preceding minimum in December 2008, cycle 24 must have now entered its long declining phase, as none of the past observed cycles had longer delays between minimum and maximum. Therefore, the average solar activity should progressively decrease towards a minimum around 2020. However, over the next 2 or 3 years, we can still expect other strong but brief peaks of activity caused by the appearance of a few big complex groups, a typical feature of the late phase of solar cycles.

We are currently over six years into solar cycle 24. This the smallest sunspot cycle since solar cycle 14 which had a maximum of 64.2 in February of 1906. 

The “Maunder Minimum” period is named after the solar astronomer Edward Walter Maunder (1851-1928), who while working at The Royal Observatory at Greenwich discovered the dearth of sunspots during the 1650-1700 period.

Time will tell whether the sun will once again go into another “Maunder Minimum” within the lifetime of the present generation, and what affect it will have on our climate.

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Tauranga August Average Daily Afternoon Temperatures 1913-2015

Weather Eye
with John Maunder

Temperatures have been recorded in the Tauranga area at several sites in the last 100 years, including the current Tauranga Airport site from June 1990.

The graph shows details of the average daily maximum temperatures, called simply ‘afternoon' for Tauranga for August from 1913-2015. The average for August 2015 was 15.0 degrees Celsius.

The long-term average afternoon temperature in August for Tauranga is 14.8 degrees Celsius. The coolest August months have been 1932 with 13.8 degrees Celsius, and 1941 and 1992 recording 13.9 degrees Celsius. The warm August months have been 2013 with 16.7 degrees Celsius, and 1915 with 16.4 degrees Celsius, while 2009 had 16.2 degrees Celsius.

The graph of the average afternoon temperatures for August shows generally normal variations from August to August during the last 100 years.

But several recent August months have been a little warmer than others since 1913.  This includes August 2013,  the warmest on record with a temperature of 16.7 degrees Celsius, which was 1.9 degrees Celsius above average. In comparison, the value for August 2014 was 15.4 degrees Celsius, which was 1.3 degrees Celsius colder than August 2013.

From 1913 to 2015, there have been 11 August months with an average afternoon temperature of 15.8 degrees Celsius or more.

Thirteen August months have had an average afternoon temperature of less than 14.3 degrees Celsius.

The sixth warmest August months – in terms of afternoon temperatures – on record in chronological order are: 1915, 1967, 1971, 2009, 2012 and 2013.

By contrast, the fifth coolest August months – in terms of afternoon temperatures – on record, in chronological order are: 1932, 1941, 1966, 1992 and 2004.

The average afternoon temperatures during August for the period 1914-1962 were 14.7 degrees Celsius, compared with 15.0 degrees Celsius from 1963 to 2011.

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Tauranga August Rainfalls 1898-2015


Weather Eye
with John Maunder

Rainfalls for the month of August have been recorded in Tauranga since 1898, except for 1904, 1907, 1908 and 1909.

The graph shows the range of rainfalls from an extreme high of 274 mm in 2010 to a low of only 17 mm in 1914.

The second wettest August was 1916 when 263 mm was recorded, and the second driest August was in 1982 when only 31 mm fell.

The long-term average rainfall for Tauranga for August is 124 mm. The rainfall for Tauranga for August  2015 was 151 mm.

The graph of the August rainfall shows normal variations from year-to-year. There is a small decrease in the overall August rainfalls during the last 50 years – from 1961-2010 – from an average of 121 mm, compared with an average of 133 mm during the 50 years from 1911-1960.

Since 1898, there have been 11 August months with a rainfall of 220 mm or more – with 10 occurring during 1900 to 1976 – and only one August month since then 2010, which was the highest rainfall for any August. Only five August months have had rainfalls of 50 mm or less.

Chronologically, the 11 wettest August months are 1913, 1916, 1920, 1927, 1938, 1942, 1957, 1965, 1970, 1976 and 2010.

In contrast, chronologically the five driest August months are 1914, 1921, 1982, 1983 and 2002.



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Global Monthly Temperatures: January 1979 to June/July 2015


Weather Eye
with John Maunder

A graph of five global monthly temperatures January 1979 to June/July 2015 is shown below.

As the base period for the individual temperature estimates varies, they have all been normalised by comparing with the average value of the initial 120 months – or 10 years – from January 1979 to December 1988.

The heavy black line represents the simple running 37-month average of the average of all five temperature records.

The numbers shown in the lower right corner represent the temperature anomaly relative to the individual 1979-1988 averages.

It should be kept in mind that satellite and surface-based temperature estimates are derived from different types of measurements, and comparing them directly as done in the diagram above therefore may be somewhat problematical.

However, the different types of temperature estimates appear to agree quite well as to the overall temperature variations on a two-three year scale. Although, on a shorter time scale there are often considerable differences between the individual records.

All five global temperature estimates presently show a general overall stagnation, at least since 2002. As indicated on the chart, there has been no real increase in global air temperature since 1998, which was affected by the oceanographic El Nino event.

This stagnation doesn't exclude the possibility that global temperatures will begin to increase again later.

On the other hand, it also remains a possibility that Earth just now is passing a temperature peak, and global temperatures will begin to decrease during the coming years.

Time will show which of these two possibilities is correct.

One of the key global temperature graphs is monthly average surface air temperature – the thin line – since 1979 according to the Goddard Institute for Space Studies, at Columbia University, New York City, USA. The thick line is the simple running 37-month average. The graph is updated to July 2015.

The following link will take you directly to a monthly very comprehensive newsletter with global meteorological information updated to Jul 2015.

http://www.climate4you.com

The website referred to above is produced by Professor Ole Humlum, of the Institute of Geosciences, University of Oslo, Norway.

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Global Average Temperatures of the Troposphere 1979 to July 2015

 
Weather Eye
with John Maunder

The latest global average temperatures of the troposphere – those observed from National Oceanic and Atmospheric Administration satellites – are computed by the University of Alabama at Huntsville in the United States.

The above chart shows that since 1979, when reliable satellite observations became available, there has been little overall trend, from the average temperatures during the 30-year period from 1981-2010 in the tropospheric temperatures, apart from a period of warmer temperatures since about 1997.

Of significance there seems to be very little change in the overall global tropospheric temperatures during the last 18 years since 1997.

The troposphere is the lowest layer of Earth's atmosphere. It contains approximately 75 per cent of the atmosphere's mass and 99 per cent of its water vapour and aerosols. The average depth of the troposphere is approximately 17 km in the middle latitudes.

The tropospheric temperature data for 2011 is January 0.0 degrees Celsius, February -0.02, March -0.10, April +0.12, May +0.14, June +0.32, July +0.38, August +0.33, September +0.29, October +0.12, November +0.12, December +0.10 degrees.

The data for 2012 is: January -0.09 degrees, February -0.12, March +0.11, April +0.29, May +0.29, June +0.37, July +0.28, August +0.34, November +0.28, December +0.20 degrees.

The data for 2013 is: January +0.50 degrees, February +0.18, March +0.20, April +0.10, May +0.07, June +0.30, July +0.17, August +0,16, September +0.37, October +0.29, November +0.19, December +0.23 degrees.

The data for 2014 is: January +0.30 degrees, February +0.18, March +0.17, April +0.19, May +0.33, June +0.31, July +0.30, August +0.20, September +0.30, October +0.37, November +0.33, and December +0.33 degrees Celsius.

The data for 2015 is: January +0.20 degrees C, February +0.18 degrees C,  March +0.14 degrees C, April +0.07 degrees C, May  +0.30 degrees C,  June +0.32 degrees C, and July +0.18 degrees C, as as shown on the chart.

The coolest months since 1979 were September 1984, with minus 0.49 degrees Celsius, and November 1984, with minus 0.42 degrees Celsius.

The warmest months were February and April 1998, both plus 0.76 degrees Celsius.

The chart shows the El Nino warming in the 1998 period, and the Mount Pinatubo, volcanic, cooling during 1992-1993.

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Meteorology and Philately


Weather Eye
with John Maunder

On July 1 (Canada Day) Canada Post unveiled five new stamps designed to showcase one of Canadians' most popular topics: the weather. The five stamps, issued to coincide with the 175th anniversary of continuous weather observing in Canada, feature weather phenomena in all their photographic splendour.


The five photographs come from every corner of Canada. Daryl Benson snapped hoar frost covering a tree near Beaumont, Alberta. Geoff Whiteway focused on hazy, early-morning fog at Cape Spear Lighthouse National Historic Site in Newfoundland and Labrador. In Saint-Gideon, Quebec, Mike Grandmaison chased a rain shower to shoot a double rainbow, while Dave Reede captured radiant flashes of lightning near Winnipeg, Manitoba. Further north, in Iqaluit, Nunavut, Frank Reardon caught rarely witnessed sun dogs, created by ice crystals in the air, and posted the photograph on The Weather Network, where Canada Post discovered it.

“From coast-to-coast-to-coast Canada is known for its diversity, and weather is no exception. The images captured in weather wonders illustrate the natural beauty that can be seen across our country,” says the Honourable Lisa Raitt, Minister of Transport, responsible for Canada Post.

“Canadians love to talk about the weather,” says Canada Post President and CEO Deepak Chopra. “Our stamp programmme celebrates the people, stories and attributes that capture the Canadian experience and we can all reminisce on a special weather moment.”

Many countries ( including New Zealand) have also published stamps relating to a weather/climate topic and a a Finish climatologist (Reino Heino)  has made an in-depth study of this subject. Some of his research was published in 2008 in assocaiated with the World Meteorological Organization (WMO) and the Universal Postal Union (UPU). The title of his book  “From Weather Gods to Modern Meteorology: A  Philatelic Journey” is highly recommended. This  book of meteorology-related stamps and postal history items,  traces the development of weather-related activities, as illustrated in the philatelic pictorial material published by the postal administration of numerous countries.

Tauranga July Rainfalls 1898-2015


Weather Eye
with John Maunder

Rainfalls for the month of July have been recorded in Tauranga since 1898, except for 1904, 1907, 1908, and 1909.

The graph for the period 1898-2015 shows the range of rainfalls from an extreme high of 348 mm in 1951, to a low of only 2 mm in 1902. The rainfall for July 2015 was 91 mm.

The graph shows the second wettest July was 2012 when 328 mm was recorded, and the second driest July was in 1983 when only 22 mm fell. The long-term average rainfall for Tauranga for July is 129 mm.

The graph of the July rainfall shows ‘normal' variations from year to year. There is a very small decrease in the overall July rainfalls during the last 50 years (1961-2010) from an average of 127 mm, compared with an average of 132 mm during the 50 years from 1911-1960.

Since 1898, there have been 13 July months with a rainfall of 200 mm or more, but only four July months with rainfalls of 40 mm or less. Interestingly, there have been two occasions in July when rainfalls of more than 200 mm occurred in adjacent years (1979, 1978 and 2007, 2009).

The ten wettest July months (in chronological order) have been 1905, 1927, 1938, 1951,1963,1979,1988, 2007, 2008, and 2012.

The ten driest July months ( in chronological order) have been 1902, 1918, 1922, 1949, 1969, 1975, 1983, 1997, 2001, and 2010,



Tauranga July Average Afternoon Temperatures 1913-2015


Weather Eye
with John Maunder

The graph below shows details of the average daily maximum temperatures, called ‘afternoon', for Tauranga for July from 1913-2015. The temperatures for July 2015 was 14.1 degrees Celsius C , the coolest since July 2004, and 1.1 degrees Celsius cooler than July 2014.

It's very common for areas such as Tauranga to have had different observation sites during the years, and readings from the earlier sites have been adjusted to the present site using standard climatologically procedures.
It's considered the temperature series described here is a fair and true record of what the temperature would have been if the current observation site, Tauranga Airport, had been used throughout the period.

It's important to note, in considering climate change, the methodology used in computing an official set of climate observations is very important as otherwise erroneous conclusions may be drawn.

Traditionally, temperature observations have been recorded with a set of maximum and minimum temperature thermometers.

These record the daily maximum temperature, usually recorded in mid-afternoon, and daily minimum temperature, usually recorded just before dawn.

This analysis of temperatures for Tauranga is for average daily maximum temperatures.

The long-term average afternoon temperature in July for Tauranga is 14.1 degrees Celsius, ranging from cool July months of 1918 and 1939, both 12.3 degrees Celsius, and 1965, with 12.9 degrees Celsius.

Warm July months included 1916 and 2010, both 15.8 degrees Celsius, and 1915 with 15.7 degrees Celsius.

The graph of the average afternoon temperatures for July shows generally normal variations from June to June in the last 100 years.

But several July months since 1997 have been a little warmer than July months since 1913.

From 1913 to 2014, there have been 10 July months with an average afternoon temperature of 15 degrees Celsius or more, and 11 July months with an average afternoon temperature of less than 13.3 degrees Celsius.

The value for July 2015 was 14.1 degrees Celsius, compared with 15.2 degrees Celsius in July last year.

The 10 warmest July months for afternoon temperatures on record, in chronological order are: 1915, 1916, 1917, 1984, 1985, 1998, 2000, 2011, 2012, and 2014.

By contrast, the seven coolest July months for afternoon temperatures on record, in chronological order are: 1918, 1929, 1935, 1939, 1963, 1965, and 1969.

The average afternoon temperature for Tauranga for July for 49 years from 1914-1962 was 14.0 degrees Celsius, compared with the average afternoon temperature for Tauranga for July for 49 years from 1963-2011 was 14.2 degrees Celsius.

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Arctic and Antarctic Sea Ice: Contrasting Data
 
Weather Eye
with John Maunder

Arctic sea ice extent for June 2015 averaged 11.0 million square kilometers,  the third lowest June extent in the satellite record. This is 920,000 square kilometers below the 1981 to 2010 long-term average of 11.89 million square kilometers and 150,000 square kilometers  above the record low for the month observed in 2010.

Sea ice extent in Antarctica averaged 14.93 million square kilometers , the third highest June extent in the satellite record. The extent was slightly greater than the 1981 to 2010 average almost everywhere around the continent. The high amount of sea ice in the eastern Weddell and Ross seas is consistent with the pattern observed for the past several months. Satellite data show unusually extensive sea ice growth along the western side of the Antarctic Peninsula. This new feature in sea ice growth could be influenced by the strong atmospheric wave-3 pattern that has persisted over the past few months. In a wave-3 pattern, there are three major low-pressure areas around the continent separated by three high-pressure areas.

The National Snow and Ice Data Centre, in Boulder, Colorado, has an extensive website on Arctic and Antarctic sea ice.

Graphs of the extent of the Northern Hemisphere and Southern Hemisphere ice – updated to June 2015 – from the above website are shown below.

These show from 1979 to 2015 the Northern Hemisphere ice extent decreased at the rate of 3.6 per cent per decade, compared with an increase of 1.9 per cent per decade during the same period in the Southern Hemisphere.


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The Sun and the next 'Maunder Minimum' 2030-2040?


Weather Eye
with John Maunder

A new model of the Sun's interior is producing predictions of its behaviour with unprecedented accuracy; predictions with interesting consequences for Earth. Professor Valentina Zharkova of Northumbria University presented results for a new model of the Sun's interior dynamo in a talk at the Astronomical Society meeting last week. (http://astronomynow.com/2015/07/09/royal-astronomical-societys-national-astronomy-meeting-2015-report-4/)

The Sun has an approximately 11-year activity cycle. During peak periods, it exhibits lots of solar flares and sunspots. Magnetic bubbles of charged particles (coronal mass ejections) may burst from the surface during this period, streaming material into space. These ejections can affect satellites and power lines on Earth. However, during lull periods, such activity may almost stop altogether. But the 11-year cycle isn't quite able to predict all of the Sun's behaviour — which can seem erratic at times. Zharkova and her colleagues (Professor Simon Shepherd of Bradford University, Dr Helen Popova of Lomonosov Moscow State University, and Dr Sergei Zarkhov of Hull University) have found a way to account for the discrepancies called a ‘double dynamo' system.

The Sun, like all stars, is a large nuclear fusion reactor that generates powerful magnetic fields, similar to a dynamo. The model developed by Kharkov's team suggests there are two dynamos at work in the Sun; one close to the surface and one deep within the convection zone. They found this dual dynamo system could explain aspects of the solar cycle with much greater accuracy than before — possibly leading to enhanced predictions of future solar behaviour. “We found magnetic wave components appearing in pairs; originating in two different layers in the Sun's interior. They both have a frequency of approximately 11 years, although this frequency is slightly different [for both] and they are offset in time,” says Zharkova. The two magnetic waves either reinforce one another to produce high activity or cancel out to create lull periods.

 
Comparison of three images over four years apart illustrates how the level of solar activity has risen from near minimum to near maximum in the Sun's 11-years solar cycle. Image credit: SOHO/ESA/NASA.

Professor Zharkova and her colleagues used magnetic field observations from the Wilcox Solar Observatory in California for three solar cycles, from the period of 1976 to 2008. In addition, they compared their predictions to average sunspot numbers — another strong marker of solar activity. All the predictions and observations matched closely. Their predictions using the model suggest an interesting longer-term trend beyond the 11-year cycle.
 
It shows that solar activity is expected to fall by 60 % during the 2030's, to conditions last seen during the ‘Maunder Minimum*' of 1645-1715. “Over the cycle, the waves fluctuate between the Sun's northern and southern hemispheres. Combining both waves together and comparing to real data for the current solar cycle, we found that our predictions showed an accuracy of 97 %,” says Zharkova.

The model predicts that the magnetic wave pairs will become increasingly offset during the Solar Cycle 25, which peaks in 2022. Then during Cycle 26, which covers the decade from 2030-2040, the two waves will become exactly out of synch, cancelling one another out. This will cause a significant reduction in solar activity. “In Cycle 26, the two waves exactly mirror each other, peaking at the same time but in opposite hemispheres of the Sun. We predict that this will lead to the properties of a ‘Maunder minimum',” says Zharkova.

The sun was well observed during the period of the original “Maunder Minimum” and this lack of sunspots is well documented.This period of solar inactivity corresponded to a climatic period called the ‘Little Ice Age' when in Europe rivers that were normally ice-free, froze and snow fields remained at low altitudes throughout the year. There is evidence the sun had similar periods of inactivity during the years 1100-1250 and 1460-1550.

The connection between solar activity and the earth's climate is an area of ongoing and sometimes controversial research.Time will tell whether the sun will once again go into another “Maunder Minimum” within the lifetime of the present generation, and what affect it will have on our climate.

*The "Maunder Minimum" is the name given to the period from 1650 to 1700 when the number of sunspots became almost zero.  The period is named after the solar astronomer Edward Walter Maunder (1851-1928) who  while working at The Royal Observatory, Greenwich discovered the dearth of sunspots during the 1650-1700 period.

During one 30 year period within the Maunder Minimum there were only about  50 sunspots compared with a more typical 40,000.  Maunder was a driving force in the foundation of the British Astronomical Association, and was a fellow of the Royal Astronomical Society.

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The following lists the various WeatherEyes and the web site address in SunLive for them. For ease of reference the full text of  the WeatherEyes is also included.
 
 
Updated: July 20, 2015

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List of WeatherEyes
 
Column 1 "Tauranga rainfalls since 1898" is available at:
 
Column 2 " No trend in February rainfall" is available at 
 
Column 3 " Changing Spots on the Sun" is available at
 
Column 4 " March Rainfalls in Tauranga: Wetter during the last 50 years" is available at 
 
Column 5 " New Zealand Climate Extremes: Tauranga has one of them" is available at  
 
Column 6 "Tauranga April Rainfalls 1898-2011" is available at
 
Column 7 " Climate Change and Villach - what is the connection? is available at
 
Column 8 " Tauranga May Rainfalls 1898-2011" is available at
 
Column 9  "Global Annual Temperatures: 1880-2012" is available at
 
Column 10  "Tauranga June Rainfalls 1898-2011"  is available at
 
 Column 11 "Are we getting warmer or not?  Global monthly temperatures 1996-2012"
 
Column 12  "Tauranga July Rainfalls 1898-2011"  is available at
 
Column 13   "England -Winters of the last 200 years" is available at 
 
 
Column 14  "Tauranga August Rainfalls 1898-2011"  is available at
 
Column 15  "Tauranga September Rainfalls 1898-2011"  is available at
 
Column 16  "Tauranga February Rainfalls 1898-2013" is available at
 
Column 17  "Tauranga Annual Afternoon Temperatures 1913-2013" is available at
 
Column 18  "Tauranga March Afternoon Temperatures 1913-2013" is available at
 
Column 19  "Tauranga April Rainfalls 1898-2013" is available at
 
Column 20  "Tauranga April Afternoon Temperatures 1913-2013" is available at
 
Column 21  "Sunpots and the Maunder Butterfly"  is available at
 
 Column 22  "A eye on Tauranga May Rainfall 1898-2013"  is available at
 
 Column 23  "A eye on Tauranga May Afternoon Temperatures 1913-2013"  is available at
 
 Column 24  "Tauranga June Rainfalls 1898-2013"  is available at
 
 Column 25  "Tauranga June Afternoon Temperatures 1913-2013"  is available at
 
Column 26 "Global monthly temperatures over the1ast 15 years: no warming or cooling
  
Column 27 "Tauranga July Rainfalls 1898-2013"  is available at 
http://www.sunlive.co.nz/blogs/printer-friendly/4996-july-tauranga-rainfalls.html
 
Column 28 "Tauranga July Afternoon Temperatures 1913-2013" is available at 
 
Column 29 "The weather dice and the butterfly"  is available at 
Column 30 "Climate Extremes in New Zealand" is available at 
Column 31 "Tauranga August Rainfalls 1898-2013" is available at 
 
Column 32 "Tauranga August Afternoon Temperatures 1913-2013"  is available at 

http://www.sunlive.co.nz/blogs/printer-friendly/5209-august-afternoon-temperatures.html

Column 33 "The first 33 WeatherEyes" is available at 

http://www.sunlive.co.nz/blogs/printer-friendly/5231-where-to-find-weathereye.html

 
Column 34 "Tauranga September Rainfalls 1898 - 2013"  is available at 

http://www.sunlive.co.nz/blogs/printer-friendly/5285-tauranga-september-rainfalls-18982013.html

Column 35 "Tauranga September Afternoon  Temperatures 1914- 2013"  is available at  
 
Column 36 "Is the Arctic Ice decreasing or increasing'"  is available at   http://www.sunlive.co.nz/blogs/printer-friendly/5380-is-arctic-sea-ice-decreasing-or-increasing.html
 
Column 37 "Temperatures in Central England from 1650-2013"  is available at 
 
 
Column 38 "Tauranga's October rainfall 1898-2013: October 2013 third driest" is available at: 
 
Column 39 "Tauranga October Afternoon Temperatures 1914-2013" is available at 
 

Column 40. "Global Surface Temperatures : Stable since 2000"  is available at:

Column 41. "Global Average Temperatures Observed from Satellites 1979-2013"  is available at:

Column 42. "Tauranga's November Rainfalls 1898-2013" is available at:

Column 43. "Tauranga's November Afternoon Temperatures 1913-2013: warmest on record" is available at: http://www.sunlive.co.nz/blogs/5627-november-2013-warmest-on-record.html

Column 44. "In the Bleak Mid-Winter" is available at:

http://www.sunlive.co.nz/blogs/printer-friendly/5662-in-bleak-midwinter.html

Column 45. "Tauranga's December Rainfalls 1898-2013" is available at:

http://www.sunlive.co.nz/blogs/printer-friendly/5717-taurangas-december-rainfalls-18982013.html

Column 46. "Tauranga's December Afternon Tempeartures 1914 2013" is available at:

http://www.sunlive.co.nz/blogs/5776-taurangas-december-afternoon-temperatures-19132013.html

Column 47. "Tauranga's Annual  Rainfalls 1898-2013" is available at:

http://www.sunlive.co.nz/blogs/5747-tauranga-annual-rainfalls-18982013.html

Column 48. "Tauranga's Annual afternoon Temperatures 1914-2013" is available at:

http://www.sunlive.co.nz/blogs/5807-taurangas-warmest-year-is-2013.html

Column 49. "Tauranga's January Rainfalls 1898-2014" is available at:

http://www.sunlive.co.nz/blogs/5840-taurangas-january-rainfalls-18982014.html

Column 50.  "Groundhog Day February 2" is available at:

http://www.sunlive.co.nz/blogs/5878-weather-groundhog-day-way.html

Column 51. "Tauranga's January Afternon Temperatures 1914-2014" is available at:

http://www.sunlive.co.nz/blogs/5929-taurangas-january-average-daily-temperatures-19142014.html

Column 52. "Global Temperatures 1880-2013  ...  Are we really getting warmer?" is available at:

http://www.sunlive.co.nz/blogs/5980-global-temperatures-18802013-are-we-really-getting-warmer.html

Column 53. "Tauranga's February Rainfalls 1898-2014" is available at:

http://www.sunlive.co.nz/blogs/6026-taurangas-february-rainfalls-18982014.html

Column 54. "Tauranga's February Afternoon Temperatures 1915-2014" is available at:

http://www.sunlive.co.nz/blogs/6079-taurangas-february-afternoon-temperatures-19142014.html

Column 55. "Tropospheric Average Temperatures 1979-2014" is available at:

http://www.sunlive.co.nz/blogs/6124-tropospheric-global-temperatures.html

Column 56. "Sunspots" is available at:

http://www.sunlive.co.nz/blogs/6164-sunspots.html

Column 57. "Tauranga's March Rainfalls 1898-2014" is available at:

http://www.sunlive.co.nz/blogs/6199-taurangas-march-rainfalls-from-18982014.html

Column 58. "Climate Extremes In NZ  -Tauranga has one of them" is available at:

http://www.sunlive.co.nz/blogs/6236-climate-extremes-nz-tauranga-has-one.html

Column 59. "Tauranga's March Afternoon Temperatures 1915-2014" is available at:

http://www.sunlive.co.nz/blogs/6289-march-average-afternoon-temperatures-19152014.html

Column 60 "Arctic and Antarctic ice" is available at:

http://www.sunlive.co.nz/blogs/6358-arctic-and-antarctica-ice.html

Column 61. "Tauranga's April Rainfalls 1898-2014" is available at:

http://www.sunlive.co.nz/blogs/6397-taurangas-april-rainfalls-18982014.html

Column 62. "Tauranga's April Afternoon Temperatures 1913-2014" is available at:

http://www.sunlive.co.nz/blogs/6434-taurangas-average-april-afternoon-temperatures-19132014.html

Column 63. "Tropospheric Global Temperatures January 1979 to April 2014" is available at:

http://www.sunlive.co.nz/blogs/6479-tropospheric-global-temperatures-january-1979-to-april-2014.html

Column 64. "Climate Change - Methods of Inferring/Detecting Changes" is available at::

http://www.sunlive.co.nz/blogs/6532-climate-change-methods-of-inferringdetecting-changes.html

Column 65. "Tauranga's May Rainfalls 1898-2014. 2014 Fifth Driest" is available at:

http://www.sunlive.co.nz/blogs/6575-taurangas-fifth-driest-may-last-month.html

Column 66. "Tauranga's May Afternoon Temperatures 1913-2014" is available at:

http://www.sunlive.co.nz/blogs/6643-taurangas-may-afternoon-temperatures-19132014.html

Column 67. "Planet Earth... the last 420,000 years" is available at:

http://www.sunlive.co.nz/blogs/6682-planet-earth-last-420000-years.html

Column 68. "The Maunder Minimum and Sunspots" is available at:

http://www.sunlive.co.nz/blogs/6725-the-maunder-minimum-and-sunspots.html

Column 69. "Tauranga's June Rainfalls 1898-2014" is available at:

http://www.sunlive.co.nz/blogs/6752-taurangas-june-rainfalls-18982014.html

Column 70. "Tauranga's June Afternoon Temperatures - Warmest in 100  Years" is available at:

http://www.sunlive.co.nz/blogs/6791-last-month-taurangas-warmest-june-100-years.html

Column 71. "Global Tropospheric Temperatures: January 1979 - June 2014" is available at:

Column 72. "Brisbane has coldest morning for 102 years" is available at:

Column 73. "Climate Change ...Have things changed" is available at:


Column 74. "Tauranga's July Afternoon Temperatures - 1913-2014" is available at:

Column 75. "Polar ice: Less ice in the Arctic, more in the Antarctic" is available at:

Column 76. "The Year Without a Summer: 1816" is available at:

Column 77. "Sunspots and the Maunder Minimum" is available at:


Column 78. "1816 - The Year without a Summer" is available at:
 

Column 79. "Tauranga August Rainfalls 1898-2014" is available at:


Column 80. "Tauranga's August Afternoon Temperatures - 1913-2014" is available at:


Column 81. "Is Global Warming taking a break" is available at:

Column 82. "UN Climate Summit" is available at:

Column 83. "Tauranga September Rainfalls 1898-2014" is available at:

Column 84. "Tauranga's September Afternoon Temperatures - 1913-2014" is available at:

Column 85. "Global Monthly Temperatures: January 1979 - August 2014" is available at:

Column 86. "Tauranga October Rainfalls 1898-2014" is available at:

Column 87. In the Bleak Mid-winter" is available at:

Column 88. "Global Monthly Temperatures: January 1979 - October 2014" is available at

Column 89. "Tauranga December Rainfalls" 1898-2014" is available at

Column 90. "Tauranga December Afternoon Temperatures" 1914-2014" is available at

Column 91. "Global Average Tropospheric Temperatures: January 1979 - December 2014" is available at

Column 92. "Tauranga January Rainfalls" 1898-2015" is available at

Column 93. "Tauranga January Afternoon Temperatures" 1914-2015" is available at

Column 94. "Tauranga Annual Rainfalls" 1898-2014" is available at


Column 95. "Tauranga Annual Average Afternoon Temperatures" 1914-2014" is available at


Column 96. "Tauranga February Afternoon Temperatures" 1914-2015" is available at


Column 97. "Tauranga February Rainfalls" 1898-2015" is available at


Column 98. "Sunspots and the Maunder Minimum:  2015 update" is available at

Column 99. "World Meteorological Day - 2015" is available at

Column 100. "The Weather Dice and the Butterfly" is available at

Column 101. "Tauranga March Rainfalls" 1898-2015" is available at

Column 102. "Tauranga March Afternoon Temperatures 1914-2015" is available at

Column 103. "Climate Extremes in New Zealand" is available at

Column 104. "Tauranga April Rainfalls" 1898-2015" is available at

Column 105. "Tauranga April Afternoon Temperatures 1913-2015" is available at

Column 106. "Global Average Temperatures of the Troposphere 1970 to April 2015" is available at

Column 107. "Global Monthly Temperatures  - January 1979  to April 2015" is available at

Column 108. "Sunspots  and the Solar Cycle" is available at

Column 109. "Tauranga May Rainfalls" 1898-2015" is available at


Column 110. "Tauranga May Afternoon Temperatures 1913-2015" is available at


Column 111. "Global Monthly Temperatures  - January 1979  to April/May 2015" is available at


Column 112. "The Year without a Summer" is available at

Column 113. "Tauranga June Rainfalls" 1898-2015" is available at


Column 114. "Tauranga June Afternoon Temperatures" 1915-2015" is available at

Column 115. "The Sun and the Maunder Minimum 2030-2040" is available at


Column 116. "Arctic and Antarctic Ice: Contrasting Data" is available at

Column 117. "Tauranga July Afternoon Temperatures" 1913-2015" is available at


Column 118. "Tauranga July Rainfalls" 1898-2015" is available at


Column 119. "Meteorology and Philately" is available at


Column 120. "Global Average Temperatures of the Troposphere 1970 to July 2015" is available at


Column 121. "Global Monthly Temperatures  - January 1979  to June/July 2015" is available at



Column 122. "Tauranga August Rainfalls 1898-2015" is available at

Column 123. "Tauranga August Afternoon Temperatures" 1913-2015" is available at


Column 124. "Solar Activity and the Earth's Climate" is available at

Column 125. "What are El Nino and La Nina" is available at

Column 126. "Tauranga September Rainfalls 1898-2015" is available at


Column 127. "Tauranga September Afternoon Temperatures" 1913-2015" is available at






















































































Column 121:"Global Monthly Average Temperatures  January 1979 - June/July 2015" is available at



Column 122 "Tauranga August Rainfalls 1898-2015"  is available at:



Column 123 "Tauranga August Afternoon Temperatures 1913-2015"  is available at:


Column 124 "Solar Activity and the Earth's Climate" is available at:



Column 125 "What are El Nino and La Nina" is available at:


Column 126 "Tauranga September Rainfalls 1898-2015"  is available at:


Column 127 "Tauranga September Afternoon Temperatures 1913-2015"  is available at:








































































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Solar Activity and the Earth’s Climate


Weather Eye
with John Maunder

A sunspot is a relatively dark, sharply defined region on the solar disc - marked by an umbra (dark area) which is 2000 degrees Celsius cooler than the effective photosphere temperature. The average diameter of a sunspot is 4000 km, but can exceed 200,000 km.

The NASA Solar Physics website ( and other web sites such as the Royal Observatory of Belgium) includes information on sunspot numbers, the ‘Maunder Minimum', and sunspot cycle predictions. The  sunspot index is updated monthly and available from 1749. The last time the monthly sunspot number was above 100 for any significant period of time was September 2002 when the value was 109.6, and the last time the value was above 200 was in August 1990 when the value was 200.3.

The recent decline in solar activity may have helped cause the recent/current “hiatus” in the pace of “global warming”.
The maximum of solar cycle 24 was reached in April 2014, with a maximum of the 13-month smoothed sunspot number at 81.8. Since then, solar activity has steadily declined (the monthly mean sunspot number is now around 50).

Therefore, solar cycle 24 proved to be 30% weaker than the previous solar cycle, which reached 119.7 in July 2000, and thus belongs to the category of moderate cycles, like cycles 12 to 15, which were the norm in the late 19th and early 20th century.

As this late maximum comes more than 5 years after the preceding minimum in December 2008, cycle 24 must have now entered its long declining phase, as none of the past observed cycles had longer delays between minimum and maximum. Therefore, the average solar activity should progressively decrease towards a minimum around 2020. However, over the next 2 or 3 years, we can still expect other strong but brief peaks of activity caused by the appearance of a few big complex groups, a typical feature of the late phase of solar cycles.

We are currently over six years into solar cycle 24. This the smallest sunspot cycle since solar cycle 14 which had a maximum of 64.2 in February of 1906. 

The “Maunder Minimum” period is named after the solar astronomer Edward Walter Maunder (1851-1928), who while working at The Royal Observatory at Greenwich discovered the dearth of sunspots during the 1650-1700 period.

Time will tell whether the sun will once again go into another “Maunder Minimum” within the lifetime of the present generation, and what affect it will have on our climate.


Tauranga August Average Daily Afternoon Temperatures 1913-2015

 
Weather Eye
with John Maunder

Temperatures have been recorded in the Tauranga area at several sites in the last 100 years, including the current Tauranga Airport site from June 1990.

The graph shows details of the average daily maximum temperatures, called simply ‘afternoon' for Tauranga for August from 1913-2015. The average for August 2015 was 15.0 degrees Celsius.

The long-term average afternoon temperature in August for Tauranga is 14.8 degrees Celsius. The coolest August months have been 1932 with 13.8 degrees Celsius, and 1941 and 1992 recording 13.9 degrees Celsius. The warm August months have been 2013 with 16.7 degrees Celsius, and 1915 with 16.4 degrees Celsius, while 2009 had 16.2 degrees Celsius.

The graph of the average afternoon temperatures for August shows generally normal variations from August to August during the last 100 years.

But several recent August months have been a little warmer than others since 1913.  This includes August 2013,  the warmest on record with a temperature of 16.7 degrees Celsius, which was 1.9 degrees Celsius above average. In comparison, the value for August 2014 was 15.4 degrees Celsius, which was 1.3 degrees Celsius colder than August 2013.

From 1913 to 2015, there have been 11 August months with an average afternoon temperature of 15.8 degrees Celsius or more.

Thirteen August months have had an average afternoon temperature of less than 14.3 degrees Celsius.

The sixth warmest August months – in terms of afternoon temperatures – on record in chronological order are: 1915, 1967, 1971, 2009, 2012 and 2013.

By contrast, the fifth coolest August months – in terms of afternoon temperatures – on record, in chronological order are: 1932, 1941, 1966, 1992 and 2004.

The average afternoon temperatures during August for the period 1914-1962 were 14.7 degrees Celsius, compared with 15.0 degrees Celsius from 1963 to 2011.

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Tauranga August Rainfalls 1898-2015

 
Weather Eye
with John Maunder

Rainfalls for the month of August have been recorded in Tauranga since 1898, except for 1904, 1907, 1908 and 1909.

The graph shows the range of rainfalls from an extreme high of 274 mm in 2010 to a low of only 17 mm in 1914.

The second wettest August was 1916 when 263 mm was recorded, and the second driest August was in 1982 when only 31 mm fell.

The long-term average rainfall for Tauranga for August is 124 mm. The rainfall for Tauranga for August  2015 was 151 mm.

The graph of the August rainfall shows normal variations from year-to-year. There is a small decrease in the overall August rainfalls during the last 50 years – from 1961-2010 – from an average of 121 mm, compared with an average of 133 mm during the 50 years from 1911-1960.

Since 1898, there have been 11 August months with a rainfall of 220 mm or more – with 10 occurring during 1900 to 1976 – and only one August month since then 2010, which was the highest rainfall for any August. Only five August months have had rainfalls of 50 mm or less.

Chronologically, the 11 wettest August months are 1913, 1916, 1920, 1927, 1938, 1942, 1957, 1965, 1970, 1976 and 2010.

In contrast, chronologically the five driest August months are 1914, 1921, 1982, 1983 and 2002.


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Meteorology and Philately


Weather Eye
with John Maunder

On July 1 (Canada Day) Canada Post unveiled five new stamps designed to showcase one of Canadians' most popular topics: the weather. The five stamps, issued to coincide with the 175th anniversary of continuous weather observing in Canada, feature weather phenomena in all their photographic splendour.


The five photographs come from every corner of Canada. Daryl Benson snapped hoar frost covering a tree near Beaumont, Alberta. Geoff Whiteway focused on hazy, early-morning fog at Cape Spear Lighthouse National Historic Site in Newfoundland and Labrador. In Saint-Gideon, Quebec, Mike Grandmaison chased a rain shower to shoot a double rainbow, while Dave Reede captured radiant flashes of lightning near Winnipeg, Manitoba. Further north, in Iqaluit, Nunavut, Frank Reardon caught rarely witnessed sun dogs, created by ice crystals in the air, and posted the photograph on The Weather Network, where Canada Post discovered it.

“From coast-to-coast-to-coast Canada is known for its diversity, and weather is no exception. The images captured in weather wonders illustrate the natural beauty that can be seen across our country,” says the Honourable Lisa Raitt, Minister of Transport, responsible for Canada Post.

“Canadians love to talk about the weather,” says Canada Post President and CEO Deepak Chopra. “Our stamp programmme celebrates the people, stories and attributes that capture the Canadian experience and we can all reminisce on a special weather moment.”

Many countries have also published stamps relating to a weather/climate topic and a a Finish climatologist (Reino Heino)  has made an in-depth study of this subject. Some of his research was published in 2008 in assocaiated with the World Meteorological Organization (WMO) and the Universal Postal Union (UPU). The title of his book  “From Weather Gods to Modern Meteorology: A  Philatelic Journey” is highly recommended. This  book of meteorology-related stamps and postal history items,  traces the development of weather-related activities, as illustrated in the philatelic pictorial material published by the postal administration of numerous countries.

Tauranga July Rainfalls 1898-2015


Weather Eye
with John Maunder

Rainfalls for the month of July have been recorded in Tauranga since 1898, except for 1904, 1907, 1908, and 1909.

The graph for the period 1898-2015 shows the range of rainfalls from an extreme high of 348 mm in 1951, to a low of only 2 mm in 1902. The rainfall for July 2015 was 91 mm.

The graph shows the second wettest July was 2012 when 328 mm was recorded, and the second driest July was in 1983 when only 22 mm fell. The long-term average rainfall for Tauranga for July is 129 mm.

The graph of the July rainfall shows ‘normal' variations from year to year. There is a very small decrease in the overall July rainfalls during the last 50 years (1961-2010) from an average of 127 mm, compared with an average of 132 mm during the 50 years from 1911-1960.

Since 1898, there have been 13 July months with a rainfall of 200 mm or more, but only four July months with rainfalls of 40 mm or less. Interestingly, there have been two occasions in July when rainfalls of more than 200 mm occurred in adjacent years (1979, 1978 and 2007, 2009).

The ten wettest July months (in chronological order) have been 1905, 1927, 1938, 1951,1963,1979,1988, 2007, 2008, and 2012.

The ten driest July months ( in chronological order) have been 1902, 1918, 1922, 1949, 1969, 1975, 1983, 1997, 2001, and 2010,


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Tauranga July Average Afternoon Temperatures 1913-2015


Weather Eye
with John Maunder

The graph below shows details of the average daily maximum temperatures, called ‘afternoon', for Tauranga for July from 1913-2015. The temperatures for July 2015 was 14.1 degrees Celsius C , the coolest since July 2004, and 1.1 degrees Celsius cooler than July 2014.

It's very common for areas such as Tauranga to have had different observation sites during the years, and readings from the earlier sites have been adjusted to the present site using standard climatologically procedures.
It's considered the temperature series described here is a fair and true record of what the temperature would have been if the current observation site, Tauranga Airport, had been used throughout the period.

It's important to note, in considering climate change, the methodology used in computing an official set of climate observations is very important as otherwise erroneous conclusions may be drawn.

Traditionally, temperature observations have been recorded with a set of maximum and minimum temperature thermometers.

These record the daily maximum temperature, usually recorded in mid-afternoon, and daily minimum temperature, usually recorded just before dawn.

This analysis of temperatures for Tauranga is for average daily maximum temperatures.

The long-term average afternoon temperature in July for Tauranga is 14.1 degrees Celsius, ranging from cool July months of 1918 and 1939, both 12.3 degrees Celsius, and 1965, with 12.9 degrees Celsius.

Warm July months included 1916 and 2010, both 15.8 degrees Celsius, and 1915 with 15.7 degrees Celsius.

The graph of the average afternoon temperatures for July shows generally normal variations from June to June in the last 100 years.

But several July months since 1997 have been a little warmer than July months since 1913.

From 1913 to 2014, there have been 10 July months with an average afternoon temperature of 15 degrees Celsius or more, and 11 July months with an average afternoon temperature of less than 13.3 degrees Celsius.

The value for July 2015 was 14.1 degrees Celsius, compared with 15.2 degrees Celsius in July last year.

The 10 warmest July months for afternoon temperatures on record, in chronological order are: 1915, 1916, 1917, 1984, 1985, 1998, 2000, 2011, 2012, and 2014.

By contrast, the seven coolest July months for afternoon temperatures on record, in chronological order are: 1918, 1929, 1935, 1939, 1963, 1965, and 1969.

The average afternoon temperature for Tauranga for July for 49 years from 1914-1962 was 14.0 degrees Celsius, compared with the average afternoon temperature for Tauranga for July for 49 years from 1963-2011 was 14.2 degrees Celsius.

Arctic and Antarctic Sea Ice: Contrasting Data


Weather Eye
with John Maunder

Arctic sea ice extent for June 2015 averaged 11.0 million square kilometers,  the third lowest June extent in the satellite record. This is 920,000 square kilometers below the 1981 to 2010 long-term average of 11.89 million square kilometers and 150,000 square kilometers  above the record low for the month observed in 2010.

Sea ice extent in Antarctica averaged 14.93 million square kilometers , the third highest June extent in the satellite record. The extent was slightly greater than the 1981 to 2010 average almost everywhere around the continent. The high amount of sea ice in the eastern Weddell and Ross seas is consistent with the pattern observed for the past several months. Satellite data show unusually extensive sea ice growth along the western side of the Antarctic Peninsula. This new feature in sea ice growth could be influenced by the strong atmospheric wave-3 pattern that has persisted over the past few months. In a wave-3 pattern, there are three major low-pressure areas around the continent separated by three high-pressure areas.

The National Snow and Ice Data Centre, in Boulder, Colorado, has an extensive website on Arctic and Antarctic sea ice.

Graphs of the extent of the Northern Hemisphere and Southern Hemisphere ice – updated to June 2015 – from the above website are shown below.

These show from 1979 to 2015 the Northern Hemisphere ice extent decreased at the rate of 3.6 per cent per decade, compared with an increase of 1.9 per cent per decade during the same period in the Southern Hemisphere.



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The Sun and the next 'Maunder Minimum' 2030-2040?


Weather Eye
with John Maunder

A new model of the Sun's interior is producing predictions of its behaviour with unprecedented accuracy; predictions with interesting consequences for Earth. Professor Valentina Zharkova of Northumbria University presented results for a new model of the Sun's interior dynamo in a talk at the Astronomical Society meeting last week. (http://astronomynow.com/2015/07/09/royal-astronomical-societys-national-astronomy-meeting-2015-report-4/)

The Sun has an approximately 11-year activity cycle. During peak periods, it exhibits lots of solar flares and sunspots. Magnetic bubbles of charged particles (coronal mass ejections) may burst from the surface during this period, streaming material into space. These ejections can affect satellites and power lines on Earth. However, during lull periods, such activity may almost stop altogether. But the 11-year cycle isn't quite able to predict all of the Sun's behaviour — which can seem erratic at times. Zharkova and her colleagues (Professor Simon Shepherd of Bradford University, Dr Helen Popova of Lomonosov Moscow State University, and Dr Sergei Zarkhov of Hull University) have found a way to account for the discrepancies called a ‘double dynamo' system.

The Sun, like all stars, is a large nuclear fusion reactor that generates powerful magnetic fields, similar to a dynamo. The model developed by Kharkov's team suggests there are two dynamos at work in the Sun; one close to the surface and one deep within the convection zone. They found this dual dynamo system could explain aspects of the solar cycle with much greater accuracy than before — possibly leading to enhanced predictions of future solar behaviour. “We found magnetic wave components appearing in pairs; originating in two different layers in the Sun's interior. They both have a frequency of approximately 11 years, although this frequency is slightly different [for both] and they are offset in time,” says Zharkova. The two magnetic waves either reinforce one another to produce high activity or cancel out to create lull periods.

 
Comparison of three images over four years apart illustrates how the level of solar activity has risen from near minimum to near maximum in the Sun's 11-years solar cycle. Image credit: SOHO/ESA/NASA.

Professor Zharkova and her colleagues used magnetic field observations from the Wilcox Solar Observatory in California for three solar cycles, from the period of 1976 to 2008. In addition, they compared their predictions to average sunspot numbers — another strong marker of solar activity. All the predictions and observations matched closely. Their predictions using the model suggest an interesting longer-term trend beyond the 11-year cycle.
 
It shows that solar activity is expected to fall by 60 % during the 2030's, to conditions last seen during the ‘Maunder Minimum*' of 1645-1715. “Over the cycle, the waves fluctuate between the Sun's northern and southern hemispheres. Combining both waves together and comparing to real data for the current solar cycle, we found that our predictions showed an accuracy of 97 %,” says Zharkova.

The model predicts that the magnetic wave pairs will become increasingly offset during the Solar Cycle 25, which peaks in 2022. Then during Cycle 26, which covers the decade from 2030-2040, the two waves will become exactly out of synch, cancelling one another out. This will cause a significant reduction in solar activity. “In Cycle 26, the two waves exactly mirror each other, peaking at the same time but in opposite hemispheres of the Sun. We predict that this will lead to the properties of a ‘Maunder minimum',” says Zharkova.

The sun was well observed during the period of the original “Maunder Minimum” and this lack of sunspots is well documented.This period of solar inactivity corresponded to a climatic period called the ‘Little Ice Age' when in Europe rivers that were normally ice-free, froze and snow fields remained at low altitudes throughout the year. There is evidence the sun had similar periods of inactivity during the years 1100-1250 and 1460-1550.

The connection between solar activity and the earth's climate is an area of ongoing and sometimes controversial research.Time will tell whether the sun will once again go into another “Maunder Minimum” within the lifetime of the present generation, and what affect it will have on our climate.

*The "Maunder Minimum" is the name given to the period from 1650 to 1700 when the number of sunspots became almost zero.  The period is named after the solar astronomer Edward Walter Maunder (1851-1928) who  while working at The Royal Observatory, Greenwich discovered the dearth of sunspots during the 1650-1700 period.

During one 30 year period within the Maunder Minimum there were only about  50 sunspots compared with a more typical 40,000.  Maunder was a driving force in the foundation of the British Astronomical Association, and was a fellow of the Royal Astronomical Society.

Tauranga  June Average Afternoon Temperatures 1913-2015

Weather Eye
with John Maunder

Temperatures have been recorded in the Tauranga area at several sites during the last 100 years, including at the current Tauranga Airport site from June 1990.

The graph shows details of the average daily maximum temperatures, called simply ‘afternoon', for Tauranga for June from 1913-2015.

The long-term average afternoon temperature in June for Tauranga is 14.7 degrees Celsius.

The cool' June months were in 1972 with 13.0 degrees Celsius, 1936 with 13.2 degrees Celsius, and 1933 with 13.3 degrees Celsius.

The ‘warm' June months include last year , 2014 with 16.9 degrees Celsius, and 1916 and 2011, both with 16.6 degrees Celsius.

June last year had an average afternoon temperature of 16.9 degrees Celsius was the warmest June on record since observations were first made in 1913.

This compares with an average afternoon temperature in June this year of 15.4 degrees Celsius.

The graph of the average afternoon temperatures for June shows generally ‘normal' variations from June to June during the last 100 years.

But many of the last 15 June months since 1996 have been a little ‘warmer' than other June months since 1913.

From 1913 to 2015, there have been 14 June months with an average afternoon temperature of 15.6 degrees Celsius or more, and 12 June months with an average afternoon temperature of less than 13.9 degrees Celsius.

The ninth ‘warmest' June months on record, in chronological order, are: 1916, 1971, 1981, 1998, 1999, 2002, 2003, 2011 and 2014.

By contrast, the seventh ‘coolest' June months on record, in chronological order, are 1933, 1936, 1941, 1944,1969, 1972 and 1976.

The average afternoon temperature in June during the period 1914-1962 was 14.7 degrees Celsius compared with 14.8 degrees Celsius from 1963 to 2011.

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Tauranga’s June rainfalls 1898-2015


Weather Eye
with John Maunder

Rainfalls for the month of June have been recorded in Tauranga since 1898 – except for 1904, 1907, 1908 and 1909.

The graph shows the range of rainfalls from an extreme high of 381mm in 1925 to a low of 19mm in 1906.

The second wettest June was 1920, when 309mm was recorded, and the second and third driest June months were in 1959 and 2012 when only 27mm fell.

The monthly average rainfall for Tauranga for June is 131mm.

The graph of the June rainfall shows normal variations from year to year.

There is a small decrease in the overall June rainfalls during the last 50 years, from 1961-2010, from an average of 126mm, compared with an average of 139mm during the 50 years from 1911-1960.

Since 1898, there have been 17 June months with a rainfall of 200mm or more, and 11 June months with rainfalls of 50mm or less.

The rainfall for June 2015 was 35mm, which made it the sixth driest on record.

In chronological order the wettest 17 June months are: 1915, 1917, 1920, 1925, 1930, 1935, 1939, 1943, 1946, 1961, 1968, 1971, 1981, 1985, 1997, 2010, and 2014.

By contrast the driest June months in chronological order are: 1906, 1913, 1914, 1933, 1942, 1958, 1959, 1967, 2001, 2012, and 2015.

For further information on a variety of weather and climate matters see: https://sites.google.com/site/doesgodplaytheclimatedice/

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The Year without a Summer


Weather Eye
with John Maunder

 

Last week most parts of New Zealand experienced extremely cold temperatures with night time temperatures of minus 20 degrees Celsius being recorded in inland parts of North Otago and South Canterbury – only five degrees Celsius milder than NZ's lowest air temperature recorded at Eweburn in Ranfurly in Central Otago on July 17, 1905.

With these temperatures in mind, spare a few thoughts for those who lived in parts of the Northern Hemisphere in the summer of 1815 which had “no summer”.

It was 1816 that was the year without a summer, caused by dust from volcano Mount Tambora in Indonesia shrouding the earth after it erupted in early-April 1815.

In Switzerland, the damp and dismal summer of 1816 led to the creation of a significant literary work.

A group of writers, including Lord Byron, Percy Bysshe Shelley, and his future wife, challenged each other to write dark tales inspired by the gloomy and chilly weather.

During the miserable weather Mary Shelley wrote her classic novel ‘Frankenstein'.

The US Albany Advertiser went on to propose some theories about why the weather was so bizarre.

The mention of sunspots is interesting, as sunspots had been seen by astronomers.

And many people, to this day, wonder about what, if any effect, sunspots may have had on the weird weather.

What's also fascinating is the newspaper article from 1816 proposes such events be studied, so people can learn what is going on.

For example: “Many seem disposed to charge the peculiarities of the season, the present year, upon the spots on the sun”.

“If the dryness of the season has in any measure depended on the latter cause, it has not operated uniformly in different places – the spots have been visible in Europe, as well as in the United States and yet in some parts of Europe, as we have already remarked, they have been drenched with rain”.

“Without undertaking to discuss, much less to decide, on such a learned subject as this, we should be glad if proper pains were taken to ascertain, by regular journals of the weather from year to year, the state of the seasons in this country and Europe, as well as the general state of health in both quarters of the globe”.

“We think the facts might be collected, and the comparison made, without much difficulty; and when once made, that it would be of great advantage to medical men, and medical science.”

And from Wood, Gillen D'Arcy. ‘1816, The Year without a Summer'. BRANCH: Britain, Representation and Nineteenth-Century History. Ed. Dino Franco Felluga. Extension of Romanticism and Victorianism on the Net, we read the following:

“To be alive in the years 1816-18, almost anywhere in the world, meant to be hungry. Across the globe during the so-called ‘Year without a Summer' – which was, in fact, a three-year climate crisis – harvests perished in frost and drought or were washed away by flooding rains.

“Villagers in Vermont survived on hedgehogs and boiled nettles, while the peasants of Yunnan in China sucked on white clay. Summer tourists traveling in France mistook beggars crowding the roads for armies on the march.”

“Famine-friendly diseases cholera and typhus stalked the globe from India to Italy, while the price of bread and rice, the world's staple foods, skyrocketed with no relief in sight. Across a European continent devastated by the Napoleonic wars, tens of thousands of unemployed veterans found themselves unable to feed their families. They gave vent to their desperation in town square riots and military-style campaigns of arson, while governments everywhere feared revolution. In New England, 1816 was nicknamed ‘Eighteen-Hundred-and-Froze-to-Death' while Germans called 1817 ‘The Year of the Beggar'.

“In the scientific literature, the 1816's cold summer was the most significant meteorological event of the nineteenth century. The global climate emergency period of 1816-18, as a whole, offers us a clear window onto a world convulsed by weather anomalies, with human communities everywhere struggling to adapt to sudden, radical shifts in weather patterns, and to a consequent tsunami of famine, disease, dislocation and unrest.”


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Global Monthly Temperatures January 1979-April/May 2015


Weather Eye
with John Maunder

A graph of five global monthly temperatures January 1979 to April 2015 is shown below.

As the base period for the individual temperature estimates varies, they have all been normalised by comparing with the average value of the initial 120 months – or 10 years – from January 1979 to December 1988.

The heavy black line represents the simple running 37-month average of the average of all five temperature records.

The numbers shown in the lower right corner represent the temperature anomaly relative to the individual 1979-1988 averages.

It should be kept in mind that satellite and surface-based temperature estimates are derived from different types of measurements, and comparing them directly as done in the diagram above therefore may be somewhat problematical.

However, the different types of temperature estimates appear to agree quite well as to the overall temperature variations on a two-three year scale. Although, on a shorter time scale there are often considerable differences between the individual records.

All five global temperature estimates presently show a general overall stagnation, at least since 2002. As indicated on the chart, there has been no real increase in global air temperature since 1998, which was affected by the oceanographic El Nino event.

This stagnation doesn't exclude the possibility that global temperatures will begin to increase again later.

On the other hand, it also remains a possibility that Earth just now is passing a temperature peak, and global temperatures will begin to decrease during the coming years.

Time will show which of these two possibilities is correct.

One of the key global temperature graphs is monthly average surface air temperature – the thin line – since 1979 according to the Goddard Institute for Space Studies, at Columbia University, New York City, USA. The thick line is the simple running 37-month average.

The following link will take you directly to a monthly very comprehensive newsletter with global meteorological information updated to May 2015.

http://www.climate4you.com/

The website referred to above is produced by Professor Ole Humlum, of the Institute of Geosciences, University of Oslo, Norway.

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Tauranga’s May Average Afternoon Temperatures 1913-2015


Weather Eye
with John Maunder

Temperatures have been recorded in the Tauranga area at several sites during the last 100 years, including the current Tauranga Airport site from June 1990.

It's very common for areas such as Tauranga to have experienced different observation sites during the years – and the readings from the earlier sites have been adjusted to the present site using standard climatological procedures.

It's considered the temperature series described here is a fair and true record of what the temperature would have been if the current observation site (of Tauranga Airport) had been used throughout the period.

Traditionally, temperature observations have been recorded with a set of maximum and minimum temperature thermometers.

These record the daily maximum temperature – usually recorded in mid-afternoon – and daily minimum temperature – usually recorded just before dawn.

This analysis of temperatures for Tauranga is for the average daily maximum temperatures.

The graph shows details of the average daily maximum temperatures, called simply ‘afternoon', for Tauranga for May from 1913-2015. May 1964 is not included because of incomplete data.

The long-term average afternoon temperature in May for Tauranga is 16.9 degrees Celsius, ranging from the cool May months of 1936, 1940, and 1997 with an average afternoon temperature of 14.9 degrees Celsius, to the warm May months of 1916 with an average afternoon temperature of 19.3 degrees Celsius, 2011 with 19.1 degrees Celsius, and 2007 with 18.9 degrees Celsius.

The graph of the average afternoon temperatures for May shows generally normal variations from May to May.

However, the last 20 May months have been a little warmer than other May months since 1913.

From 1913 to 2015, there have been 13 May months with an average afternoon temperature of 18 degrees Celsius or more, and 11 May months with an average afternoon temperature of less than 16 degrees Celsius.

The value for May 2013 was 18.5 degrees Celsius, which is the fifth warmest on record, and for May 2014 the temperature was 18.4 degrees Celsius – the sixth warmest on record.

However, the value for May 2015 was a relatively “cool” 17.3 degrees Celsius.

The 13 warmest May months, in terms of afternoon temperatures, on record in chronological order are: 1916, 1928, 1938, 1950, 1999, 2000, 2003, 2005, 2007, 2010, 2011, 2013 and 2014.

In contrast, the 11 coolest May months, in terms of afternoon temperatures, on record in chronological order are: 1913, 1920, 1924, 1936, 1940, 1945, 1959, 1967, 1977, 1983, and 1992.

The average afternoon temperature in May during the 49-year period 1914-1962 was 16.7 degrees Celsius, compared with 17.1 degrees Celsius for the 49-year period from 1963-2011.

For more information on climate matters, see: https://sites.google.com/site/climatediceandthebutterfly/


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Tauranga May Rainfalls 1898-2015


Weather Eye
with John Maunder

Rainfalls for the month of May have been recorded in Tauranga since 1898 – except for 1904, 1907, 1908, and 1909.

The graph shows the range of rainfalls from an extreme high of 634 mm in 2005 to a low of 13 mm in 2001. The rainfall for May last year 2014 was 28 mm – the fifth driest May since records became available in 1898. The rainfall for May 2015 was 95 mm, about 25 % less than the long term average.

The second wettest May was 1950, when 311 mm was recorded, and the second driest May was in 1918, when only 24 mm fell. The long-term average rainfall for Tauranga for May is 124 mm.

Apart from the exceptional rainfall of 634 mm in May 2005, the graph shows a small decrease in overall May rainfalls when two 50-year periods are compared.

Since 1898, there have been 14 May months with a rainfall of 200 mm or more. In chronological order, the wettest May months are: 1899, 1900, 1917, 1925, 1926, 1928, 1949, 1950, 1956, 1961, 1962, 1971, 2005, and 2010.

In terms of dry May months, there have been only nine May months with rainfall of less than 40 mm. In chronological order, the driest May months are: 1901, 1918, 1939, 1941, 1978, 1991, 1999, 2007, and 2014.

Of particular significance is the exceptional rainfall in May 2005. I estimate such a rainfall is likely to occur in Tauranga only about twice in every 1000 years.

This suggests central government could have had a much more important role in financial implications of the floods, which affected many areas of Tauranga in May 2005.

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Sunspots and Solar Cycle


Weather Eye
with John Maunder

The connection between solar activity and the earth's climate is an area of on-going and sometimes controversial research.

A sunspot is a relatively dark, sharply defined region on the solar disc - marked by an umbra (dark area) which is 2000 degrees C cooler than the effective photosphere temperature. The average diameter of a sunspot is 4000 km, but can exceed 200,000 km.

The NASA Solar Physics website ( and other web sites such as the Royal Observatory of Belgium) includes information on sunspot numbers, the ‘Maunder Minimum', and sunspot cycle predictions. The  sunspot index is updated monthly and available from 1749. The last time the monthly sunspot number was above 100 for any significant period of time was September 2002 when the value was 109.6, and the last time the value was above 200 was in August 1990 when the value was 200.3.

The recent decline in solar activity may have helped cause the current “hiatus” in the pace of “global warming”.
The maximum of solar cycle 24 was reached in April 2014, with a maximum of the 13-month smoothed sunspot number at 81.8. Since then, solar activity has steadily declined (monthly mean sunspot number is now around 40).

Therefore, solar cycle 24 proved to be 30% weaker than the previous solar cycle, which reached 119.7 in July 2000, and thus belongs to the category of moderate cycles, like cycles 12 to 15, which were the norm in the late 19th and early 20th century.

As this late maximum comes more than 5 years after the preceding minimum in December 2008, cycle 24 must have now entered its long declining phase, as none of the past observed cycles had longer delays between minimum and maximum. Therefore, the average solar activity should progressively decrease towards a minimum around 2020. However, over the next 2 or 3 years, we can still expect other strong but brief peaks of activity caused by the appearance of a few big complex groups, a typical feature of the late phase of solar cycles.

We are currently over six years into solar cycle 24. This the smallest sunspot cycle since solar cycle 14 which had a maximum of 64.2 in February of 1906.    

Sunspots are typically confined to an equatorial belt, on the sun, between 35 degrees south and 35 degrees north latitude. At the beginning of a new solar cycle, sunspots tend to form at high latitudes, but as the cycle reaches a maximum – that is a large numbers of sunspots,the spots form at lower latitudes. Near the minimum of the cycle, sunspots appear even closer to the equator. And as a new cycle starts again, sunspots again appear at high latitudes. This recurrent behaviour of sunspots gives rise to the ‘Maunder Butterfly' pattern as shown in the chart from NASA.

The “Maunder Minimum” period is named after the solar astronomer Edward Walter Maunder (1851-1928), who while working at The Royal Observatory at Greenwich discovered the dearth of sunspots during the 1650-1700 period.

Time will tell whether the sun will once again go into another “Maunder Minimum” within the lifetime of the present generation, and what affect it will have on our climate.

For further information on a range of climate matters see: https://sites.google.com

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Global Monthly Temperatures January 1979 to April 2015


Weather Eye
with John Maunder

A superimposed graph of five global monthly temperatures January 1979 to April 2015 is shown below.

 

As the base period for the individual temperature estimates varies, they have all been normalised by comparing with the average value of the initial 120 months (10 years) from January 1979 to December 1988.

The heavy black line represents the simple running 37 month average of the average of all five temperature records. The numbers shown in the lower right corner represent the temperature anomaly relative to the individual 1979-1988 averages.

It should be kept in mind that satellite and surface-based temperature estimates are derived from different types of measurements, and that comparing them directly as done in the diagram above therefore may be somewhat problematical.

However, the different types of temperature estimates appear to agree quite well as to the overall temperature variations on a two-three year scale, although on a shorter time scale there are often considerable differences between the individual records.

All five global temperature estimates presently show a general overall stagnation, at least since 2002. As indicated on the chart, there has been no real increase in global air temperature since 1998, which was affected by the oceanographic El Niño event.

This stagnation does not exclude the possibility that global temperatures will begin to increase again later. On the other hand, it also remain a possibility that Earth just now is passing a temperature peak, and that global temperatures will begin to decrease during the coming years.

Time will show which of these two possibilities is correct.

Below is a link which will take you directly to a monthly newsletter with global meteorological information updated to April 2015.

http://www.climate4you.com/Text/Climate4you_April_2015.pdf

The website referred to above is produced by  Professor Ole Humlum, of the Institute of Geosciences, University of Oslo, Norway.


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Global Average Temperatures of the Troposphere - 1970 to April 2015


Weather Eye
with John Maunder

The latest global average temperatures of the troposphere – those observed from National Oceanic and Atmospheric Administration satellites – are computed by the University of Alabama at Huntsville in the United States.

The above chart shows that since 1979, when reliable satellite observations became available, there has been little overall trend, from the average temperatures during the 30-year period from 1981-2010 in the tropospheric temperatures, apart from a period of warmer temperatures since about 1997.

Of significance there seems to be very little change in the overall global tropospheric temperatures during the last 18 years since 1997.

The troposphere is the lowest layer of Earth's atmosphere. It contains approximately 75 per cent of the atmosphere's mass and 99 per cent of its water vapour and aerosols. The average depth of the troposphere is approximately 17 km in the middle latitudes.

The tropospheric temperature data for 2011 is January 0.0 degrees Celsius, February -0.02, March -0.10, April +0.12, May +0.14, June +0.32, July +0.38, August +0.33, September +0.29, October +0.12, November +0.12, December +0.10 degrees.

The data for 2012 is: January -0.09 degrees, February -0.12, March +0.11, April +0.29, May +0.29, June +0.37, July +0.28, August +0.34, November +0.28, December +0.20 degrees.

The data for 2013 is: January +0.50 degrees, February +0.18, March +0.20, April +0.10, May +0.07, June +0.30, July +0.17, August +0,16, September +0.37, October +0.29, November +0.19, December +0.23 degrees.

The data for 2014 is: January +0.30 degrees, February +0.18, March +0.17, April +0.19, May +0.33, June +0.31, July +0.30, August +0.20, September +0.30, October +0.37, November +0.33, and December +0.33 degrees Celsius.

The data for 2015 is: January +0.20 degrees C, February +0.18 degrees C,  March +0.14 degrees C, and April +0.07 degrees C, as shown on the chart.

The coolest months since 1979 were September 1984, with minus 0.49 degrees Celsius, and November 1984, with minus 0.42 degrees Celsius.

The warmest months were February and April 1998, both plus 0.76 degrees Celsius.

The chart shows the El Nino warming in the 1998 period, and the Mount Pinatubo, volcanic, cooling during 1992-1993.



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Tauranga April Afternoon Temperatures 1913-2015

 
Weather Eye
with John Maunder

Temperatures have been recorded in the Tauranga area at several sites during the last 100 years, including the current Tauranga Airport site from June 1990.

It is very common for areas such as Tauranga to have had different observation sites during the years – and the readings from the earlier sites have been adjusted to the present site using standard climatologically procedures.

The temperature series, as shown in the graph, are based on the data from the original observations from the various sites as available on the NIWA National Climate Database archive, with data from the sites prior to the Tauranga Airport site being adjusted, where appropriate, to temperatures which are likely to have been recorded at the current airport site.

Traditionally, temperature observations have been recorded with a set of maximum and minimum temperature thermometers. These record the daily maximum temperature (usually recorded in mid-afternoon), and daily minimum temperature (usually recorded just before dawn).

The graph shows details of the average daily maximum temperatures (called simply ‘afternoon'), for Tauranga for April from 1913-2015. Note April 1947 and 1964 are not included because of incomplete data.

The long-term average afternoon temperature in April for Tauranga for is 20.0 degrees Celsius, ranging from the cool April months of 1925, with an average afternoon temperature of 18.2 degrees Celsius, and 1923 with an average afternoon temperature of 18.3 degrees Celsius, to the warm April months of 1938 (22.5 degrees Celsius), and 1916 (22.4 degrees Celsius).

The graph of the average afternoon temperatures for April shows generally normal variations from April to April, with several of the last 15 April months being a little warmer than other April months.

From 1913 to 2015, there have been 13 April months with an average afternoon temperature of 21.0 degrees Celsius or more, and eight April months with an average afternoon temperature of less than 19.0 degrees Celsius.

The value for April 2015 was 20.3 degrees Celsius, very close to the long-term average.

The 13 warmest April months – in terms of afternoon temperatures – on record, in chronological order, are 1916, 1924, 1928, 1935, 1938, 1948, 1955, 1956, 1978, 1981, 2012, 2013 and 2014.

In contrast, the eight coolest April months – in terms of afternoon temperatures – on record, in chronological order, are 1923, 1925, 1940, 1941, 1949, 1980, 1991 and 1992.

The average afternoon temperatures for Tauranga for the 50 years 1914-1962, and the 50-year period 1963-2011 are both 20.0 degrees Celsius.

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Tauranga April Rainfalls 1898-2015


Weather Eye
with John Maunder

Rainfalls in Tauranga during the month of April 2014 and April 2013 were both relatively wet, with April 2013 recording 284 mm – the sixth highest April rainfall since 1898 – and April 2014 the total was 225 mm – the 17th highest April rainfall in the city since 1898. In contrast, rainfall in Tauranga for April 2015 was just a little less than the long-term average.

The graph shows the range of rainfalls from a high of 383 mm in 1911 to a low of 10 mm in 1958.

The second wettest April was 1948, when 333 mm was recorded; and the second driest was April 2010 with only 12 mm. The long-term average rainfall for Tauranga for April is 120 mm.

Since 1898, there have been 10 April months with a rainfall of 250 mm or more. In chronological order, the wettest April months are: 1911, 1923, 1935, 1938, 1948, 1959, 1995, 2000, 2001, and 2013.

In terms of dry April months, there have been nine months with rainfall of 30 mm or less. In chronological order, the driest April months are: 1898, 1910, 1913, 1919, 1958, 1979, 1984, 2005, and 2010.




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Climate Extremes in New Zealand


Weather Eye
with John Maunder

Climate extremes in New Zealand, since instrumental records became available in the 1850's, show a range from the highest temperature of 42.4 degrees Celsius recorded in Rangiora on February 7, 1973, to the most intense rainfall in 10 minutes – 34 mm which occurred in Tauranga on April 17, 1948.

The National Institute of Water and Atmospheric Research ( NIWA) updates the weather extremes recorded in New Zealand since observations were officially recorded in the 1850's. The current extremes include the following:

Wettest: A record 34 mm occurred in 10 minutes in Tauranga on April 17, 1948.

In one hour, 134 mm was recorded  at Cropp at Waterfall in the Hokitika Catchment. This site also has the NZ record for the highest 24 hours' fall of 758 mm on December 27-28, 1989, and the highest 48-hour-fall of 1049 mm on December 11-13, 1995. It also had the highest fall in a calendar month of 2827 mm in December 1995, and the highest fall in a calendar year of 16,617 mm in 1998.

Driest: Only 9 mm of rain fell at Cape Campbell, Marlborough, from January to March 2001; the driest three months ever recorded in New Zealand.

The driest six months was also recorded at Cape Campbell, from November 2000 to April 2001 when only 52 mm of rain was recorded. The driest 12 months was in Alexandra from November 1963 to October 1964, when only 167 mm was recorded. The longest period without rain is 71 days, which occurred in Wai-iti, Marlborough, from February 8, 1939.

Warmest: Until 1973, the highest temperatures officially recorded in New Zealand was 101.3 degrees Fahrenheit (38.4 degrees Celsius) at Ashburton and Darfield on January 19, 1956.

However, under extreme northwesterly conditions on February 7, 1973, there was a recorded 42.4 degrees Celsius (108.3 degrees Fahrenheit) at Rangiora. A temperature of 42.3 degree Celsius was also recorded on this day at Jordan, Marlborough.

Coldest: The coldest air temperature ever recorded was minus 25.6 degrees Celsius in Eweburn, Ranfurly, on July 17, 1903. The lowest grass temperature is minus 21.6 degrees Celsius recorded at Lake Tekapo on August 4, 1938.

Sunniest: Nelson, Takaka, Riwaka, Blenheim, Lake Tekapo, Tauranga and Whakatane often appear in the list of very sunny places in New Zealand – but officially Nelson has recorded the most sunshine in any one year with 2711 hours in 1931, with Blenheim recording 2673 hours in 1961.

In the North Island, Whakatane recorded 2602 hours of sunshine in 2012. In contrast, only 1333 hours of sunshine was recorded in Invercargill in 1983.

For one month, the sunniest location is Nelson with 336 hours in December 1934 (with Taupo recording 335 hours in December in 1950); and the least sunny location is Taumaranui, with only 27 hours in June 2002.

Wind Gust: The highest wind gusts recorded in New Zealand were 250 km/h at Mt John, Canterbury, on April 17, 1970 and 248 km/h at Hawkins Hill, Wellington, on November 6, 1959, and July 4, 1962.

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Tauranga March Afternoon Temperatures: 1914-2015


Weather Eye
with John Maunder

Temperatures have been recorded in the Tauranga area at several sites during the last 100 years including the current Tauranga Airport site from June 1990.

The graph shows details of the average daily maximum temperatures, called simply ‘afternoon', for Tauranga for the months of March from 1915-2014. March 1947 is not included because of incomplete data. The average daily maximum temperature for March 2015 was 22.8 degrees Celsius.

The long-term average afternoon temperature in March for Tauranga is 22.5 degrees Celsius, ranging from the cool March months of 1960 with an average afternoon temperature of 20.4 degrees Celsius, and 1940 with an average afternoon temperature of 20.8 degrees Celsius, to the warm March months of 1916 (24.7 degrees Celsius), and 1938 and 1968 (24.6 degrees Celsius).

The graph of the average afternoon temperatures for March shows generally normal variations from March to March.

From 1915 to 2015, there have been seven March months with an average afternoon temperature of 24.0 degrees Celsius or more, and 13 March months with an average afternoon temperature of 21.5 degrees Celsius or less.

The seven warmest March months – in terms of average afternoon temperatures on record –in chronological order are: 1913, 1914,1916, 1938, 1968, 2010 and 2013.

In contrast the 13 coolest March months – in terms of afternoon temperatures on record –in chronological order are: 1923, 1934,1936, 1940, 1944,1945, 1949, 1960, 1974, 1976, 1992, 1993 and 1998.

The average afternoon temperature for March for the 48 years from 1914-1962 was 22.4 degrees Celsius, compared with an average of 22.6 degrees Celsius for the 48 years from 1963-2011.


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Tauranga March Rainfalls 1898-2015


Weather Eye
with John Maunder

Rainfalls for the month of March have been recorded in Tauranga since 1898 – except for 1904, 1908 and 1909.

This graph below shows the range of rainfalls from a high of 504 mm in 1979, to a low of 5 mm in 1943.

The second wettest March was in 1972, when 318 mm was recorded, and two March months – 1921 and 2010 – recorded 14 mm.

The long-term average rainfall for Tauranga for March is 109 mm. The rainfall for March 2015 was 77 mm.

The graph shows no significant overall trend in rainfalls in March during the last 110 years, apart from a small increase in the average rainfall for the 50 years ending in 1960 of 103 mm, to 117 mm in the 50 years to 2010.

Since 1898, there have been eleven March months with a rainfall of 200 mm or more, and eleven March months with a rainfall of 30 mm or less.

The wettest March months in chronological order are: 1902,1918,1922,1935,1941,1944,1957,1962,1972,1979 and 1987.

The driest March months in chronological order are: 1903,1905,1921,1943,1951,1952,1953,1969, 2004, 2010 and 2013.

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The Weather Dice and the Butterfly

 
Weather Eye
with John Maunder

The Weekend Sun newspaper is published every Friday in Tauranga ( New Zealand) and contains a range of local information including comments from several columnists. During part of 2012, I provided a "Weather Eye" comment which was published on the second and fourth Friday of each month. My column was also published on the website SunLive.
 
From March 2013, the column has been published each week on Sunlive.
 
This is the 100th WeatherEye.
 
The following web site lists the various WeatherEyes and the web site address on SunLive for them. For ease of reference the full text of  the WeatherEyes is also included.
 
https://sites.google.com/site/theweatherclimateeye/

Weather dice were shown on the cover of my book  published in 1986.

The book cover, which has two dice on a "monopoly board" with various weather symbols on each side of the dice, represent the reality that most,  if not all, of the weather (and ultimately most of the climate), is ultimately related to how the weather dice fall.

Who or what controls the fall of the weather dice, and how significant the role of human induced activities is, is the ultimate question for all meteorologists and climate scientists.

However, many meteorologists consider that the atmosphere is generally in a chaotic mode and have coined the phase the the "butterfly effect",  which if correct, means that we just have to continue to live, and adapt to whatever the weather and the climate provides.

Professor Edward Lorenz (1917-2008) was a meteorologist who worked at the Massachusetts Institute of Technology (MIT) in the United States, and in 1972 presented an academic paper entitled "Predictability: Does the flap of a butterfly's wings in Brazil set off a tornado in Texas?"

This paper resulted in the development of "chaos theory" or simply "the butterfly effect" which among other things, endeavours to explain why it is so hard to make good weather forecasts beyond about 10 days, and has implications for making good climate forecasts, particularly when considering the natural causes of climate change.

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World Meteorological Day... March 23


Weather Eye
with John Maunder

The World Meteorological Organization WMO), is the successor of the International Meteorological Organization (IMO) which was created in 1873. Its fundamental mission is to support the countries of the world in providing meteorological and hydrological services to protect life and property from natural disasters related to weather, climate, and water, to safeguard the environment, and to contribute to sustainable development. This cannot happen without the necessary observations, research and operations that develop the understanding and knowledge of weather and climate.

Since 1961, World Meteorological Day has commemorated the coming into force on 23 March 1950 of the Convention establishing the World Meteorological Organization  (WMO) and the essential contribution that National Meteorological and Hydrological Services make to the safety and well-being of society. Each year, the celebrations focus on a theme of topical interest.

The theme for the 2015 World Meteorological Day  “Climate knowledge for climate action,” provides an opportunity to take stock of the climate knowledge built during the last decades, as an essential base to support the path towards more ambitious action to address climate change and climate variability.

The structure of the WMO which has headquarters in Geneva involves the Congress, the Executive Council, and eight Technical Commissions. The World Meteorological Congress, the supreme body of the Organization, assembles delegates of Members once every four years to determine general policies for the fulfilment of the purposes of the Organization; to consider membership of the Organization; to determine the general, technical, financial and staff regulations; to establish and coordinate the activities of constituent bodies of the Organization; to approve long-term plans and budget for the following financial period; to elect the President and Vice-Presidents of the Organization and members of the Executive Council; and to appoint the Secretary-General.

The Executive Council is the executive body of the Organization, which meets annually, implements decisions of Congress, coordinates the programmes, examines the utilization of budgetary resources, considers and takes action on recommendations of regional associations and technical commissions and guides their work programme, provides technical information, counsel and assistance in the fields of activity of the Organization and studies and takes action on matters affecting international meteorology and related activities.

The Council is composed of 37 directors of National Meteorological or Hydrometeorological Services, serving in an individual capacity as representatives of the Organization and not as representatives of particular Members thereof. They include the President and three Vice-Presidents who are elected by Congress, and the presidents of the six regional associations. The remaining 27 members are elected by Congress.

There are also eight Technical Commissions which are composed of experts designated by Members and are responsible for studying meteorological, climatological, and hydrological operational systems, applications and research. They establish methodology and procedures and make recommendations to the Executive Council and the Congress. The Technical Commissions usually meet once every four years, when they elect a President* and Vice-President.
 
*From 1989 to 1996, I was President of one of Technical Commissions, namely the “Commission for Climatology”

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Sunspots and the Maunder Minimum: 2015 Update


Weather Eye
with John Maunder

The “Maunder Minimum” period is named after the solar astronomer Edward Walter Maunder (1851-1928), who while working at The Royal Observatory at Greenwich discovered the dearth of sunspots during the 1650-1700 period.

During one 30-year period within the Maunder Minimum, there were only about 50 sunspots compared with a more typical 40,000. This period coincided with an extremely cold period in Europe. Maunder was a driving force in the foundation of the British Astronomical Association, and was a Fellow of the Royal Astronomical Society.

Throughout the solar cycle, which is usually about 11 years in length, the latitude of sunspot occurrences varies with an interesting pattern. The chart shows the latitude of sunspot occurrence versus time, in years.

The current prediction for Sunspot Cycle 24 gives a smoothed sunspot number maximum of about 72 in late 2013. The smoothed sunspot number reached a peak of 81.9 in April 2014. We are currently over six years into Cycle 24. The current predicted and observed size makes this the smallest sunspot cycle since Cycle 14 which had a maximum of 64.2 in February of 1906.     

Sunspots are typically confined to an equatorial belt, on the sun, between 35 degrees south and 35 degrees north latitude. At the beginning of a new solar cycle, sunspots tend to form at high latitudes, but as the cycle reaches a maximum – that is a large numbers of sunspots,the spots form at lower latitudes. Near the minimum of the cycle, sunspots appear even closer to the equator. And as a new cycle starts again, sunspots again appear at high latitudes. This recurrent behaviour of sunspots gives rise to the ‘Maunder Butterfly' pattern as shown in the chart from Nasa.

Time will tell whether the sun will once again go into another Maunder Minimum within the lifetime of the present generation, and what affect it will have on our climate.

Tauranga February Rainfalls: 1898-2015


Weather Eye
with John Maunder

Rainfalls for the month of February have been recorded in Tauranga since 1898 (except for 1904, 1908, and 1909).

The graph of February rainfalls in Tauranga shows the range of rainfalls from a high of 343 mm in 1936 to a low of only 7 mm in 1973.

The graph shows predominantly "normal" variations from year to year.

Nine February months have had a rainfall of less than 15 mm. Nine February months also have had a rainfall of 200 mm or more.

The wettest February was 1936 with 343 mm, and the second wettest February was 2001 when 268 mm was recorded.

The driest February month was 1973 with 7 mm, and the February months of 1942, 1987, and 2011 each had a rainfall of 8 mm.

The rainfall for February 2015 was 44 mm. The long-term February rainfall for Tauranga is 90 mm.

In chronological order, the wettest nine February months were 1920, 1933, 1934, 1936, 1938, 1960, 1966, 2001, and 2004.

In chronological order, the driest nine February months were 1942, 1970, 1972, 1973, 1987, 1999, 2000, 2010, and 2011.

For further Information on rainfalls in Tauranga see

Tauranga: Average Afternoon Temperatures in February - 1915-2015


Weather Eye
with John Maunder

Temperatures have been recorded in the Tauranga area at several sites during the last 100 years, including the current Tauranga Airport site from June 1990.

It is very common for areas such as Tauranga to have had different observation sites during the years; and the readings from the earlier sites have been adjusted to the present site using ‘standard climatological procedures'.

It is considered the temperature series described here is a fair and true record of what the temperature would have been if the current observation site (Tauranga Airport) had been used throughout the period.

It is important to note that in considering ‘climate change', the methodology used in computing an 'official' set of climate observations is very important – as otherwise erroneous conclusions may be drawn.

Traditionally, temperature observations have been recorded with a set of maximum and minimum temperature thermometers. These record the daily maximum temperature (usually recorded in mid-afternoon), and daily minimum temperature (usually recorded just before dawn).

This analysis of February temperatures for Tauranga is for the average daily maximum temperatures.

The graph above shows details of the average daily maximum temperatures (called simply ‘afternoon'), for Tauranga for February from 1915-2015.

The long-term average afternoon temperature in February for Tauranga is 23.8 degrees Celsius, ranging from the ‘cool' February months of 1934, with an average afternoon temperature of 21.6 degrees C , and 1921 with an average afternoon temperature of 21.8 degrees Celsius, to the ‘warm' February months of 1916 (26.4 degrees Celsius), and 1998 (26.2 degrees Celsius).

The graph of the average afternoon temperatures for February shows generally 'normal' variations from February to February.

The average afternoon February temperature for the 49 years from 1963-2011 of 24.0 degrees Celsius: this is just 0.3 degrees Celsius higher than the average afternoon February temperature for the 49 years from 1914-1962.

From 1915 to 2015, there have been six February months with an average afternoon temperature of 25.5 degrees Celsius or more, and six February months with an average afternoon temperature of 22.5 degrees Celsius or less.

The average afternoon temperature for February this year was  24.1 degrees Celsius, which was 0.2 degrees Celsius above the long term average.

The six ‘warmest' February months (in terms of afternoon temperatures) on record, in chronological order, are: 1916, 1928, 1954, 1955, 1998, and 2011.

In contrast the six ‘coolest' February months (in terms of afternoon temperatures) on record, in chronological order, are: 1921, 1931, 1934, 1940, 1976, and 2004.

Tauranga: Annual Average Afternoon Temperatures 1914-2014


Weather Eye
with John Maunder

Temperatures have been recorded in the Tauranga area at several sites in the last 100 years, including the current Tauranga Airport site from June 1990.

The graph below shows details of the average annual daily maximum temperatures (called simply 'afternoon'), for Tauranga for the years 1914-2014.

The long-term average afternoon temperatures for Tauranga for a calendar year is 18.6 degrees Celsius, including the cool years of 18.1 degrees Celsius in 1976, 18.1 degrees Celsius in 1992, 18.2 degrees Celsius in 1923, and 18.3 degrees Celsius in 1918.

In contrast, Tauranga's warmest years (in terms of the average afternoon temperature) are: 20.2 degrees Celsius in 2013, 20.1 degrees Celsius in 1916, 20.0 degrees Celsius in 1998, and 19.9 degrees Celsius in 2010.

The average afternoon temperature in 2014 was 19.8 degrees Celsius.

Since 1914, there have been eleven calendar years with an average afternoon temperature of 19.6 degrees Celsius or more. In chronological order these years are: 1914, 1915, 1916, 1928, 1998, 1999, 2005, 2010, 2011, 2013, and 2014. 

In comparison, there have been 11 calendar years with an average afternoon temperature of 18.5 degrees Celsius or less. In chronological order these years are: 1918, 1920, 1923, 1941, 1945, 1965, 1976, 1977, 1980, 1991, and 1992.

The graph of the average afternoon temperatures for the years 1914-2014 shows generally normal variations from year to year from 1915 to the mid-1990s, followed by several years of above-average temperatures, including the last recent four “warm” years: 2010, 2011, 2013, and 2014.

The annual average afternoon temperature shows a warming of about 0.8 degrees Celsius during the 51 years from 1963-2013 from 19.0  degrees Celsius, compared with 18.2 degrees Celsius during the 49 years from 1914-1962.

Tauranga Annual Rainfalls: 1898-2014

  
Weather Eye
with John Maunder

Monthly rainfalls for Tauranga have been recorded at several recording sites during the last 115 years.

From January 1898 to December 1904, the observation site was described as the Tauranga Harbour, from November 1904 to April 1907 the site was described as simply ‘Tauranga'.

From January 1910 to December 1923 the site was Waikareao, in Otumoetai; from January 1924 to September 1940 the site was at 148 Waihi Rd, in Judea; from October 1940 to January 1941 the site was at Te Puna; and from February 1941 to now, the site is Tauranga Airport.

The methodology use in adjusting the older sites to the current observing site is published in the ‘NZ Meteorological Service Miscellaneous Publication' No 180 in 1984.

It is considered that the homogeneous rainfall series described here is a fair and true record of what the rainfall would have been if the current observation site (Tauranga Airport) had been used since 1898.

This should be coupled with the understanding that although standard accepted methodologies have been used, any adjustments are only estimates of what would have occurred if the location of the rainfall records had always been in the same place with the same surroundings and the same or similar recording gauge.

In terms of climate change (such as is it getting wetter or drier, or warmer or colder), the methodology used in computing an ‘official' set of climate observations is very important, as otherwise erroneous conclusions may be drawn.

The long-term average rainfall for Tauranga for the calendar year is 1300 mm, ranging from a low of 747 mm in 2002, to a high of 2049 mm in 1962.

For comparison, the rainfall for the last year, 2014, was 1125 mm.

Since 1898, there have been only four years with a rainfall of less than 900 mm, they are 1914, 1982, 1993, and 2002.

And there's only been four years with a rainfall of more than 1800 mm; they are the two consecutive years of 1916 and 1917, plus 1938 and 1962.

The ten wettest years on record are: 1962 which had 2049 mm or 57 per cent above of the long-term average, while 1917 had 1985 mm or 52 per cent above average. Also, 1916 had 1941 mm or 49 per cent above average, plus 1938 (1817 mm), 1920 (1789 mm), 1956 (1777 mm), 1979 (1730 mm), 2011 (1696 mm), 2005 (1682 mm), and 1935 (1670 mm).

In chronological order, these wettest years occurred in 1916, 1917, 1920, 1935, 1938, 1956, 1962, 1979, 2005 and 2011.

In contrast, the 10 driest years on record are: 2002 (747 mm or 48 per cent below the long-term average), 1914 (773 mm or 41 per cent below the long-term average), 1982 (842 mm or 36 per cent below the long-term average), plus 1993 (863 mm), 1906 (950 mm), 1919 (962 mm), 1997 (978 mm), 1973 (989 mm), 1986 (991 mm), and 1999 (1002 mm).

In chronological order, these driest years occurred in 1906, 1914, 1919, 1973, 1982, 1986, 1993, 1997, 1999, and 2002.

The average rainfall in Tauranga for the 50 years 1911-60 was 1365 mm, compared with the average rainfall for the 50 years 1961-2010  of 1263 mm.

Tauranga: Average Afternoon Temperatures - January 1915-2015


Weather Eye
with John Maunder

Temperatures have been recorded in the Tauranga area at several sites during the last 100 years, including the current Tauranga Airport site from June 1990.

The graph above shows details of the average daily maximum temperatures (called simply ‘afternoon') for Tauranga for January from 1914-2015.

The long-term average afternoon temperature in January for Tauranga is 23.8 degrees Celsius, ranging from the cool January months of 1920, with 21.6 degrees Celsius, and 1939 with 21.8 degrees Celsius, to the very warm January month of 1935, with 27.7 degrees Celsius.

In 1970 the temperature reached 25.7 degrees Celsius. The average afternoon temperature in January 2015 was 25.4 degrees Celsius which was the seventh-warmest on record.

The graph of the average afternoon temperatures for January shows generally normal variations from January to January during the last 100 years.

The average January afternoon temperature during the 50 years from 1963 to 2011 of 23.8 degrees Celsius, is the same average recorded in the 50 year period from 1914 to 1962.

From 1914 to 2015, there have been seven January months with an average afternoon temperature of 25.4 degrees Celsius or higher, and seven January months with an average afternoon temperature of 22.5 degrees Celsius or lower.

The seventh-warmest January months (in terms of afternoon temperatures), on record, in chronological order, are 1915, 1935, 1970, 1957, 1999, 2009 and 2015.

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Tauranga January Rainfalls: 1898-2015 - Third driest on record


Weather Eye
with John Maunder

The graph shows the range of Tauranga's January rainfalls from 1898-2015, varied from an extreme high of 532 mm in 1907 to a low of only 1 mm in 1928. The second wettest January was 2011, when 347 mm was recorded; and the second driest January was in 2013, when only 4 mm fell.

The long-term average rainfall for Tauranga for January is 89 mm. The rainfall for January 2015 was 8 mm (also recorded in 1900 and 1957)

The graph of the January rainfall shows generally normal variations from year to year.

Since 1898 there have been eight January months with a rainfall of 180 mm or more, with two such wet January months, 1940 and 1941, being consecutive.

Fourteen January months have experienced rainfalls of less than 20 mm, with two such dry January months, 1978 and 1979, being consecutive.

In chronological order, the eighth wettest January months are 1907 with 532 mm, 1920 with 196 mm, 1940 with 254 mm, 1941 with 245 mm, 1951 with 204 mm, 1965 with 183 mm, 1989 with 268 mm, and 2011 with 347 mm.

In contrast, the sixth driest January months in chronological order are 1900 with 8 mm, 1928 with 1 mm, 1944 with 10 mm, 1957 with 8 mm, 1988 with 9 mm,  2013 with 4 mm, and 2015 with 8 mm.

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Global Average Tropospheric Temperatures: January 1979 – December 2014


Weather Eye
with John Maunder

The latest global average temperatures of the troposphere – those observed from National Oceanic and Atmospheric Administration satellites – are computed by the University of Alabama at Huntsville in the United States.

The above chart shows since 1979, when reliable satellite observations became available, there has been little overall trend, from the average temperatures during the 30-year period from 1981-2010 in the temperatures, apart from a period of warmer temperatures since about 1997.

However, of significance there appears to be very little change in the overall global tropospheric temperatures during the last 16 years.

The troposphere is the lowest layer of Earth's atmosphere. It contains approximately 75 per cent of the atmosphere's mass and 99 per cent of its water vapour and aerosols. The average depth of the troposphere is approximately 17 km in the middle latitudes.

The data for 2011 is January 0.0 degrees Celsius, February -0.02, March -0.10, April +0.12, May +0.14, June +0.32, July +0.38, August +0.33, September +0.29, October +0.12, November +0.12, December +0.10 degrees.

The data for 2012 is: January -0.09 degrees, February -0.12, March +0.11, April +0.29, May +0.29, June +0.37, July +0.28, August +0.34, November +0.28, December +0.20 degrees.

The data for 2013 is: January +0.50 degrees, February +0.18, March +0.20, April +0.10, May +0.07, June +0.30, July +0.17, August +0,16, September +0.37, October +0.29, November +0.19, December +0.23 degrees.

The data for 2014 is: January +0.30 degrees, February +0.18, March +0.17, April +0.19, May +0.33, June +0.31, July +0.30, August +0.20, September +0.30, October +0.37, November +0.33, and December +0.33 degrees Celsius.

The coolest months since 1979 were September 1984, with minus 0.49 degrees Celsius, and November 1984, with minus 0.42 degrees Celsius.

The warmest months were February and April 1998, both plus 0.76 degrees Celsius.

The chart shows the El Nino warming in the 1998 period, and the Mount Pinatubo, volcanic, cooling during 1992-1993.

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Tauranga December Afternoon Temperatures: 1913-2014


Weather Eye
with John Maunder

Temperatures have been recorded in the Tauranga area at several sites during the last 100 years, including the current Tauranga Airport site from June 1990.

The graph below shows details of the average daily maximum temperatures, called simply ‘afternoon', for Tauranga for December from 1913-2014.

The long-term average afternoon temperature in December for Tauranga is 22.1 degrees celsius, ranging from the ‘cool' December months of 2004 (20.1), 1968 (20.5) and 1944 and 1951 (both 20.7), to the ‘warm' December months of 1940 (24.4), 1937 (24.0), and 1990 (23.8).

The graph of the average afternoon temperatures for December shows generally normal variations from December-to-December during the last 100 years.

The average December afternoon temperature during the 50 years from 1963 to 2011 of 22.2 degrees Celsius is exactly the same figure recorded in the 50 years from 1914 to 1961.

The average afternoon temperature in December 2014 was 21.8 (one degree cooler than December 2013).

From 1913 to 2013, there have been 23 December months with an average afternoon temperature of 23 or more, and 12 December months with an average afternoon temperature of less than 21 or less.

The seven warmest December months (in terms of afternoon temperatures), on record, in chronological order, are 1930, 1934, 1937, 1940, 1990, 1993, and 1994.

By contrast, the seven coolest December months (in terms of afternoon temperatures), on record, in chronological order, are 1921, 1946, 1951, 1962, 1968, 1977, and 2004.


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Tauranga December Rainfalls 1914-2014


Weather Eye
with John Maunder

The graph below shows the range of Tauranga's December rainfalls, from an extreme high of 447 mm in 1962 to a low of only 4 mm in 1930.

 

The second wettest December was 2011, when 276mm was recorded; and the second driest December was in 1994, when only 14mm fell.

The long-term average rainfall for Tauranga for December is 100mm. The rainfall for December 2014 was 145 mm.

The graph of the December rainfall shows, at first glance, normal variations from year to year.

However, there has been a notable increase in December rainfalls during the last few decades. Indeed, the average December rainfall in Tauranga for the 50-year period from 1961-2010 of 109mm, is 20 per cent higher than the rainfall for the 50-year period 1911-1960.

Since 1898, there have been eight Decembers with a rainfall of 200mm or more, five of which occurred during the period 1962 to 2011.

Seven December months have experienced rainfalls of 30mm or less. Of significance are the high rainfalls in the consecutive December months of 1962 and 1963, of 447mm and 224mm respectively.

In chronological order, the eighth-wettest Decembers are 1924 with 225mm, 1928 with 227mm, 1936 with 240mm, 1962 with 447mm, 1963 with 224mm, 1996 with 241mm, 2001 with 208mm and 2011 with 276mm.

In contrast, the seventh-driest December months in chronological order are 1902 with 27mm, 1912 with 22mm, 1919 with 22mm, 1930 with 4mm, 1986 with 30mm, 1990 with 21mm and 1994 with 14mm.

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Global Monthly Temperatures: January 1979 to October 2014


Weather Eye
with John Maunder

A superimposed graph of five global monthly temperatures January 1979 to October 2014 is shown below.

As the base period differs for the individual temperature estimates, they have all been normalised by comparing with the average value of the initial 120 months (10 years) from January 1979 to December 1988.

The heavy black line represents the simple running 37 month (c. 3 year) mean of the average of all five temperature records. The numbers shown in the lower right corner represent the temperature anomaly relative to the individual 1979-1988 averages.

It should be kept in mind that satellite and surface-based temperature estimates are derived from different types of measurements, and that comparing them directly as done in the diagram above therefore may be somewhat problematical.

However, the different types of temperature estimates appear to agree quite well as to the overall temperature variations on a two-three year scale, although on a shorter time scale there are often considerable differences between the individual records.

 All five global temperature estimates presently show a general overall stagnation, at least since 2002. There has been no real increase in global air temperature since 1998, which was affected by the oceanographic El Niño event.

This stagnation does not exclude the possibility that global temperatures will begin to increase again later. On the other hand, it also remain a possibility that Earth just now is passing a temperature peak, and that global temperatures will begin to decrease during the coming years.

Time will show which of these two possibilities is correct.

Below is a link which will take you directly to a monthly newsletter with global meteorological information updated to October/November 2014.

http://www.climate4you.com/Text/Climate4you_November_2014.pdf

This website is produced by  Ole Humlum, Professor of Physical Geography, Institute of Geosciences, University of Oslo.

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In the Bleak Mid-winter


Weather Eye
with John Maunder

In the bleak mid-winter,

Frosty wind made moan,

Earth stood hard as iron,

Water like a stone,

Snow had fallen,

Snow on snow,

Snow on snow,

In the bleak mid-winter,

Long ago.

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These words, from the first verse of the well-known carol, were written by the English poet Christina Rossetti in 1872 in response to a request from the magazine ‘Scribner's Monthly' for a Christmas poem.

The carol was selected by the Queen in her TV Christmas message last year.

It was published posthumously in Rossetti's ‘Poetic Works' in 1904. The poem became a Christmas carol after it appeared in ‘The English Hymnal' in 1906.

The text of this Christmas poem has been set to music many times; the most famous settings being composed by Gustav Holst and Harold Edwin Darke in the early 20th Century.

The version by Darke is favoured by cathedral choirs, and is the one usually heard performed on the radio broadcasts of ‘Nine Lessons and Carols' by the King's College choir.

Of some significance is that on December 15 2013, the ‘Mail Online' (UK) had the following headlines relating to a severe snow storm, which hit the Holy City on Saturday – and at the same time Cairo experienced its first snowfall in more than 100 years.

Perhaps the Christmas carol has come alive?

A Christmas card come to Life: Jerusalem hit by worst snowstorm for 20 years, as eight inches fall across Holy City.

  • Unusually heavy snowfall, as temperatures dip below freezing.
  • Dome of the Rock and Western Wall bathed in white blanket.
  • Prime Minister Natanyahu gets in on the fun with family snowball fight.

The weather is always with us; and although we may all hope the weather each Christmas will be to our liking, it is perhaps important to remember that in the Southern Hemisphere where the carol ‘In the Bleak Mid-Winter' may seem unusual, there have been two significant and tragic weather and other natural disasters..

The first was on Christmas Eve in New Zealand, in 1953, when the Tangiwai rail disaster occurred with loss of 151 lives. The second was in Darwin, on Christmas Day 1974, when Tropical Cyclone Tracy killed 71 people and destroyed 80 per cent of the city's houses.

I take this opportunity of wishing all my readers a seasons greeting, and I will be back in 2015 with some more WeatherEyes.***********************************************************************************************************



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Tauranga: October Rainfalls 1898-2014


Weather Eye
with John Maunder

The graph below shows the range of Tauranga's October rainfalls, from an extreme high of 357 mm in 1916 to a low of only 7 mm in 1984.

The second wettest October was 1928, when 269 mm was recorded; and the second driest October was in 1928, when only 11 mm fell. The long-term average rainfall for Tauranga in the month of October is 110 mm. The rainfall in October 2014 was 38 mm, the thirteenth-lowest October rainfall.

The graph of the October rainfall shows at first glance normal variations from year to year. However, there has been a notable decrease in the October rainfalls during the last few years.

Indeed, the average October rainfall in Tauranga for the 50-year period from 1961-2010 of 88 mm is only 70 per cent of the rainfall for the 50-year period 1910-1960.

Since 1898, there have been 11 October months with a rainfall of 200 mm or more (10 of which occurred during the period 1900-1958), and only one October month since then has recorded this much. Ten October months have also experienced rainfalls of 25 mm or less.

In chronological order the eleven wettest October months are 1900, 1905, 1916, 1918, 1921, 1926, 1928, 1941, 1952, 1958, and 1983.  In contrast the ten driest October months are 1906, 1938, 1963, 1965, 1969, 1973, 1984, 1993, 2010, and 2013.



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Global Monthly Temperatures: January 1979 - August 2014


Weather Eye
with John Maunder

A superimposed graph of five global monthly temperatures January 1979 to August 2014 is shown below.

As the base period differs for the individual temperature estimates, they have all been normalised by comparing with the average value of the initial 120 months (10 years) from January 1979 to December 1988.

The heavy black line represents the simple running 37 month mean of the average of all five temperature records. The small numbers shown in the lower right corner represent the temperature anomaly relative to the individual 1979-1988 averages.

Below is a link which will take you directly to a monthly newsletter with global meteorological information updated to August/September 2014:

http://www.climate4you.com/Text/Climate4you_August_2014.pdf

The website is produced by  Ole Humlum, Professor of Physical Geography, Institute of Geosciences, University of Oslo.

 

All five global temperature estimates presently show an overall stagnation, at least since 2002. There has been no increase in global air temperature since 1998, which however was affected by the oceanographic El Niño event.

Professor Humlum considers that this stagnation does not exclude the possibility that global temperatures will begin to increase again later.

On the other hand, it also remain a possibility that the Earth just now is passing a temperature peak, and that global temperatures will begin to decrease during the coming years. Time will show which of these two possibilities is correct.

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Tauranga’s September Average Afternoon Temperatures: 1913-2014


Weather Eye
with John Maunder

Temperatures have been recorded in the Tauranga area at several sites in the last 100 years, including the current Tauranga Airport site from June 1990.

 

The graph shows details of the average daily maximum temperatures (simply called “afternoon”) for Tauranga for September from 1913-2014.

The long-term average afternoon temperature in September for Tauranga is 16.6 degrees C, ranging from the “cool” September months of 1964 (14.8 degrees C), and 1977 (14.9 degrees C), to the “warm” September months of 1915 (18.4 degrees C), and 18.3 degrees in 1914. The afternoon temperature for 2014 was 17.6 degrees.

The graph of the average afternoon temperatures for September shows generally "normal" variations from September to September during the last 100 years, but five of the warmest six September months occurred from 1913 to 1921.

From 1913 to 2014, there have been ten September months with an average afternoon temperature of 17.5 degrees C or more, and eight September months with an average afternoon temperature of less than 15.4 degrees C.

The tenth “warmest” September months (in terms of afternoon temperatures) on record, in chronological order, are 1913, 1914, 1915, 1916, 1921, 1926, 1940, 2006, 2009 and 2014. By contrast, the eighth “coolest” September months (in terms of afternoon temperatures) on record, in chronological order, are 1935, 1964, 1967, 1977, 1992, 1993, 1994 and 1997.

The average afternoon temperature during September for the period 1914-62 was 16.6 degrees, compared with 16.5 degrees from 1963-2011.


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Tauranga: September Rainfalls 1898-2014


Weather Eye
with John Maunder

 

Rainfall for the month of September have been recorded in Tauranga since 1898, except for 1904, 1907, 1908, and 1909.

The graph below shows the range of rainfalls from an extreme high of 274 mm in 1973 to a low of only 16 mm in 1965.

The second wettest September was in 1900, when 256 mm was recorded, and the second driest September was in 1944, when only 27 mm fell. The long-term average rainfall for Tauranga for September from 1898-2013 is 105 mm.

The graph of the September rainfall shows normal variations from year to year.

There is a very small decrease in the average for September rainfalls during the last 50 years (1961-2010) from an average of 103 mm, compared with an average of 105 mm during the 50 years from 1911-1960.  

Since 1898, there have been five Septembers with a rainfall of 200 mm or more (four of which occurred during the period 1900 to 1928, but there's only been since then), compared with six September months with a rainfalls of 40 mm or less.

The rainfall for September 2014 was 101 mm.

In chronological, order the ten wettest September months (rainfalls over 180 mm)  are 1900,1912,1919,1923,1928,1946,1960,1969,1971 and 1973.

In contrast the eleven driest September months (rainfalls of 50 mm or less) are 1910, 1913, 1914, 1921, 1922, 1944, 1965, 1993, 1987, 2006 and 2011. 

The average rainfall for Tauranga for September for the 50 years 1961-2010 of 103 mm is similar to the rainfall for the previous 50 years (1910-1960).



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UN Climate Summit 2014


Weather Eye
with John Maunder

The following is a summary of the Climate Conference held in New York on September 23:

The purpose of the 2014 Climate Summit was to raise political momentum for a meaningful, universal climate agreement in Paris in 2015 and to galvanize transformative action in all countries to reduce emissions and build resilience to the adverse impacts of climate change.

An unprecedented number of world leaders attended the Summit, including 100 Heads of State and Government. They were joined by more than 800 leaders from business, finance and civil society.  This summary details their most significant announcements.

A comprehensive global vision on climate change emerged from the statements of leaders at the Summit including the following:

Leaders acknowledged that climate action should be undertaken within the context of efforts to eradicate extreme poverty and promote sustainable development.

Leaders committed to limit global temperature rise to less than 2 degrees Celsius from pre-industrial levels.

Many leaders called for all countries to take national actions consistent with a less than 2 degree C pathway and a number of countries committed to doing so.

Leaders committed to finalise a meaningful, universal new agreement under the United Nations Framework Convention on Climate Change (UNFCCC) in Paris in 2015, and to arrive at the first draft of such an agreement at a meeting in Lima, in December 2014.

Leaders concurred that the new agreement should be effective, durable and comprehensive and that it should balance support for mitigation and adaptation.  Many underlined the importance of addressing loss and damage.

Many leaders, from all regions and all levels of economic development advocated for a peak in greenhouse gas emissions before 2020, dramatically reduced emissions thereafter, and climate neutrality in the second-half of the century.

Leaders from more than 40 countries, 30 cities and dozens of corporations launched a large-scale commitment to double the rate of global energy efficiency by 2030 through vehicle fuel efficiency, lighting, appliances, buildings and district energy.

Seventy-three national Governments, 11 regional governments and more than 1,000 businesses and investors signalled their support for pricing carbon. Together these leaders represent 52 per cent of global GDP, 54 per cent of global greenhouse gas emissions and almost half of the world's population.

Some leaders agreed to join a new Carbon Pricing Leadership Coalition to drive action aimed at strengthening carbon pricing policies and redirecting investment

Note. Of course not all of the world's media were focused on the Climate Summit.

Indeed, Christopher Booker, writing in the UK's Daily Telegraph, stated: “Apart from the Middle East, there can have been few more depressing places to be in the world last Tuesday than the UN General Assembly in New York, where an endless queue of world leaders, including Barack Obama and David Cameron, treated an increasingly soporific audience to leaden little appeals for humanity to take urgent action to halt global warming.”

For a full summary of the summit, click here.

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Is Global Warming taking a break?

 
Weather Eye
with John Maunder

The UN Secretary-General Ban Ki-moon has invited world leaders, from government, finance, business, and civil society to Climate Summit 2014 and this summit will be held this week in New York.

The aim of the conference is to galvanize and catalyse climate action.  The Secretary General has asked world leaders to bring bold announcements and actions to the Summit that will reduce emissions, strengthen climate resilience, and mobilize political will for a meaningful legal agreement in 2015. I will summarise the finding of this conference next week.  

Meantime, the so called global warming is currently taking a break. Global temperatures rose drastically into the late 1990's, but the global average temperature has risen only slightly since 1998 , which is too many people is surprising, considering most climate models predicted considerable warming due to rising greenhouse gas emissions. Several so called climate sceptics, although I much prefer the term climate realists, have used this apparent contradiction to question many aspects of the climate change story – or at least the harm potential caused by greenhouse gases – as well as the validity of the climate models.

However, the majority of climate scientists continue to emphasize that the short-term warming hiatus could largely be explained on the basis of current scientific understanding and did not contradict longer term warming.

Researchers have been looking into the possible causes of the warming hiatus during the last few years.  Reto Knutti, professor of climate physics at ETH Zurich, in Switzerland, has systematically examined all current hypotheses. In a study published in the latest issue of the journal ‘Nature Geoscience', he concludes that two important factors are equally responsible for the hiatus.

One of the important reasons is natural climate fluctuations, of which the weather phenomena El Nino and La Nina in the Pacific are the most important and well known. "1998 was a strong El Nino year, which is why it was so warm that year," says Reto.

In contrast, the counter-phenomenon La Nina has made the past few years cooler than they would otherwise have been.

The second important reason for the ‘warming hiatus' is that solar irradiance has been weaker than predicted in the last few years. This is because the identified fluctuations in the intensity of solar irradiance are unusual at the present time. In general, sunspot cycles each lasted about 11 years in the past, but for unknown reasons the last period of weak solar irradiance lasted 13 years.

Furthermore, several volcanic eruptions, such as Eyjafjallajökull in Iceland in 2010, have increased the concentration of floating particles (aerosols) in the atmosphere, which has further weakened the solar irradiance arriving at the Earth's surface.


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Tauranga’s August Average Afternoon Temperatures 1914-2014


Weather Eye
with John Maunder

Temperatures have been recorded in the Tauranga area at several sites in the last 100 years, including the current Tauranga Airport site from June 1990.

The graph shows details of the average daily maximum temperatures, called simply ‘afternoon' for Tauranga for August from 1913-2014.

The long-term average afternoon temperature in August for Tauranga is 14.8 degrees Celsius, with the cool August months of 1932 with 13.8 degrees Celsius, and 1941 and 1992 both with 13.9 degrees Celsius.

The warm August months have been 2013 with 16.7 degrees Celsius, and 1915 with 16.4 degrees Celsius, while 2009 had 16.2 degrees Celsius.

The graph of the average afternoon temperatures for August shows generally normal variations from August to August during the last 100 years.

But four of the last August months have been a little warmer than others since 1913.

This includes August 2013, which was 1.9 degrees Celsius above average and the warmest on record.

In comparison, the value for August 2014 was 15.4 degrees Celsius, which was 1.3 degrees Celsius colder than August 2013.

From 1913 to 2013, there have been 11 August months with an average afternoon temperature of 15.8 degrees Celsius or more.

Thirteen August months have had an average afternoon temperature of less than 14.3 degrees Celsius.

The sixth warmest August months – in terms of afternoon temperatures – on record in chronological order are: 1915, 1967, 1971, 2009, 2012 and 2013.

By contrast, the fifth coolest August months – in terms of afternoon temperatures – on record in chronological order are: 1932, 1941, 1966, 1992 and 2004.

The average afternoon temperatures during August for the period 1914-1962 were 14.7 degrees Celsius, compared with 15 degrees Celsius from 1963 to 2011.

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Tauranga August Rainfalls 1898-2014





Weather Eye
with John Maunder

Rainfalls for the month of August have been recorded in Tauranga since 1898, except for 1904, 1907, 1908 and 1909.

The graph shows the range of rainfalls from an extreme high of 274mm in 2010 to a low of only 17mm in 1914.

The second wettest August was 1916 when 263mm was recorded, and the second driest August was in 1982 when only 31mm fell.

The long-term average rainfall for Tauranga for August is 124mm. The rainfall for Tauranga for July 2014 was 82mm.

The graph of the August rainfall shows normal variations from year-to-year. There is a small decrease in the overall August rainfalls during the last 50 years – from 1961-2010 – from an average of 121mm, compared with an average of 13 mm during the 50 years from 1911-1960.

Since 1898, there have been 11 August months with a rainfall of 220mm or more – with 10 occurring during 1900 to 1976 – and only one August month since then 2010, which was the highest rainfall for any August. Only five August months have had rainfalls of 50mm or less.

Chronologically, the 11 wettest August months are 1913, 1916, 1920, 1927, 1938, 1942, 1957, 1965, 1970, 1976 and 2010.

In contrast, chronologically the five driest August months are 1914, 1921, 1982, 1983 and 2002.




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1816: The Year without a Summer


Weather Eye
with John Maunder

As discussed in a previous Weathereye, 1816 was ‘The year without a summer', caused by dust from Mount Tambora in Indonesia shrouding the earth after it erupted in early-April 1815.

And with the sunlight blocked 1816 did not have a normal summer.

In Switzerland, the damp and dismal summer of 1816 led to the creation of a significant literary work.

A group of writers, including Lord Byron, Percy Bysshe Shelley, and his future wife, challenged each other to write dark tales inspired by the gloomy and chilly weather.

During the miserable weather Mary Shelley wrote her classic novel ‘Frankenstein'.

The Albany Advertiser went on to propose some theories about why the weather was so bizarre.

The mention of sunspots is interesting, as sunspots had been seen by astronomers.

And many people, to this day, wonder about what, if any effect, sunspots may have had on the weird weather.

What's also fascinating is the newspaper article from 1816 proposes such events be studied, so people can learn what is going on. For example:

“Many seem disposed to charge the peculiarities of the season, the present year, upon the spots on the sun.

“If the dryness of the season has in any measure depended on the latter cause, it has not operated uniformly in different places – the spots have been visible in Europe, as well as in the United States and yet in some parts of Europe, as we have already remarked, they have been drenched with rain.

“Without undertaking to discuss, much less to decide, such a learned subject as this, we should be glad if proper pains were taken to ascertain, by regular journals of the weather from year to year, the state of the seasons in this country and Europe, as well as the general state of health in both quarters of the globe.

“We think the facts might be collected, and the comparison made, without much difficulty; and when once made, that it would be of great advantage to medical men, and medical science.”

Today, we now know volcanoes can pose many hazards. One hazard is volcanic ash can be a threat to jet aircraft where ash particles can be melted by the high operating temperature.

The melted particles then adhere to the turbine blades and alter their shape, disrupting the operation of the turbine.

Large eruptions can affect temperature, as ash and droplets of sulphuric acid obscure the sun and cool the Earth's lower atmosphere, or troposphere.

However, they also absorb heat radiated up from the Earth, thereby warming the upper atmosphere, or stratosphere.

Historically, so-called volcanic winters have caused catastrophic famines.

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Sunspots and the Maunder Minimum


Weather Eye
with John Maunder

The Maunder Minimum period is named after the solar astronomer Edward Walter Maunder (1851-1928), who while working at The Royal Observatory at Greenwich discovered the dearth of sunspots during the 1650-1700 period.


During one 30-year period within the Maunder Minimum, there were only about 50 sunspots compared with a more typical 40,000. This period coincided with an extremely cold period in Europe.

Maunder was a driving force in the foundation of the British Astronomical Association, and was a Fellow of the Royal Astronomical Society.

Throughout the solar cycle, of about 11 years, the latitude of sunspot occurrences varies with an interesting pattern. The chart shows the latitude of sunspot occurrence versus time, in years.

Sunspots are typically confined to an equatorial belt, on the sun, between 35 degrees south and 35 degrees north latitude.

At the beginning of a new solar cycle, sunspots tend to form at high latitudes, but as the cycle reaches a maximum – that is a large numbers of sunspots – the spots form at lower latitudes.

Near the minimum of the cycle, sunspots appear even closer to the equator. And as a new cycle starts again, sunspots again appear at high latitudes. This recurrent behaviour of sunspots gives rise to the ‘Maunder Butterfly' pattern shown.

Time will tell whether the sun will once again go into another Maunder Minimum within the lifetime of the present generation, and what affect it will have on our climate.

A graph of the sunspot numbers, from 1700 to July 2014, is shown below. The graph is from a website of the Royal Belgium Observatory.



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The Year Without a Summer: 1816


Weather Eye
with John Maunder

The peculiar 19th Century weather disaster – dubbed The Year Without a Summer – happened in 1816, when weather in Europe and North America took a bizarre turn which resulted in widespread crop failures and famine.

On April 10, 1815, Mount Tambora in Indonesia produced the largest eruption known on the planet during the last 10,000 years.

The volcano erupted more than 50 cubic kilometres of magma. The eruption produced global climatic effects and killed more than 100,000 people, directly and indirectly.

Pyroclastic flows reached the sea on all sides of the peninsula, and heavy tephra fall devastated croplands, causing an estimated 60,000 fatalities.

Entire villages were buried under thick pumice deposits. Some of the settlements have recently been brought back to light by archaeological excavations, making the site a called ‘Pompeii of Indonesia'.

While the death toll of people living on Sumbawa and surrounding coastal areas was high enough, even more fatalities can be attributed to an indirect effect of global climate deterioration after the eruption.

These changes turned 1816 into ‘The Year without a Summer' for much of Europe, causing widespread famine. It's estimated it caused the death of more than 100,000 people.

The reason for the climatic changes was increased absorption of sunlight due to a veil of aerosols dispersed around both hemispheres by stratospheric currents from the tall eruption column.

Global temperatures dropped by as much as three degrees Celsius in 1816.

‘The Year without a Summer' was well reported in the United States and Europe, as the following description suggests.

The weather in 1816 was unprecedented. Spring arrived but then everything seemed to turn backward, as cold temperatures returned. The sky seemed permanently overcast. The lack of sunlight became so severe farmers lost their crops and food shortages were reported in Ireland, France, England, and the United States.

In Virginia, Thomas Jefferson retired from the presidency and farming at Monticello sustained crop failures that sent him further into debt.

It would be more than a century before anyone understood the reason for the peculiar weather disaster: the eruption of an enormous volcano on a remote island in the Indian Ocean one year earlier had thrown enormous amounts of volcanic ash into the upper atmosphere.

For further information, see: www.volcanodiscovery.com/tambora.html or see http://history1800s.about.com/od/crimesanddisasters/a/The-Year-Without-A-Summer.htm

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Polar ice: Less ice in Arctic, more in Antarctic

 
Weather Eye
with John Maunder

Arctic sea ice extent declined at a fairly rapid rate through the first three weeks of July, but the loss rate then slowed due to a shift in weather patterns.

In Antarctica, the advance of sea ice nearly halted for about a week in early July, and then resumed. At the end of the month, Antarctic extent was at or near a record high for this time of year.

The National Snow and Ice Data Centre, in Boulder, Colorado, has an extensive website on Arctic and Antarctic sea ice. For details, see: http://nsidc.org/data/seaice_index/

In the Arctic, the July 2014 average ice extent was 8.25 million square kilometres. This is 1.85 million square kilometres less than the 1981 to 2010 average for July.

July 2014 is the fourth lowest Arctic sea ice extent in the satellite record, with 340,000 square kilometres more than the previous record lows in July 2011, 2012, and 2007.

The monthly linear rate of decline for July is 7.4 per cent, per decade.

Arctic sea ice reached its annual maximum extent for 2014 on March 21.

Overall, the 2014 Arctic sea ice coverage was the fifth lowest in the 1978-2014 record.

In contrast, Antarctic sea ice reached its annual minimum for 2014 on February 23.

This is the fourth highest Antarctic minimum in the satellite record. This continues a strong pattern of greater-than-average sea ice extent in Antarctica for the last two years.

Graphs of the extent of the Northern Hemisphere and Southern Hemisphere ice – updated to July 2014 – from the above website are shown below.

These show from 1979 to 2014 the Northern Hemisphere ice extent decreased at the rate of 7.4 per cent per decade, compared with an increase of 1.2 per cent per decade during the same period in the Southern Hemisphere.


For further information on the climate science scene see: https://sites.google.com/site/climatediceandthebutterfly/


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Tauranga’s Afternoon Temperatures: July 1913-2014


Weather Eye
with John Maunder

Temperatures have been recorded in the Tauranga area at several sites during the last 100 years, including the current Tauranga Airport site from June 1990.

The graph below shows details of the average daily maximum temperatures, called ‘afternoon' for Tauranga for July from 1913-2014.

It's very common for areas such as Tauranga to have had different observation sites during the years, and readings from the earlier sites have been adjusted to the present site using standard climatologically procedures.

It's considered the temperature series described here is a fair and true record of what the temperature would have been if the current observation site, Tauranga Airport, had been used throughout the period.

It's important to note, in considering climate change, the methodology used in computing an official set of climate observations is very important as otherwise erroneous conclusions may be drawn.

Traditionally, temperature observations have been recorded with a set of maximum and minimum temperature thermometers.

These record the daily maximum temperature, usually recorded in mid-afternoon, and daily minimum temperature, usually recorded just before dawn.

This analysis of temperatures for Tauranga is for average daily maximum temperatures.

The long-term average afternoon temperature in July for Tauranga is 14.1 degrees Celsius, ranging from cool July months of 1918 and 1939, both 12.3 degrees Celsius, and 1965, with 12.9 degrees Celsius.

Warm July months included 1916 and 2010, both 15.8 degrees Celsius, and 1915 with 15.7 degrees Celsius.

The graph of the average afternoon temperatures for July shows generally normal variations from June to June in the last 100 years.

But several July months since 1997 have been a little warmer than July months since 1913.

From 1913 to 2014, there have been 10 July months with an average afternoon temperature of 15 degrees Celsius or more, and 11 July months with an average afternoon temperature of less than 13.3 degrees Celsius.

The value for July 2013 was 14.9 degrees Celsius, and July this year was 15.2 degrees Celsius.

The 10 warmest July months for afternoon temperatures on record, in chronological order are: 1915, 1916, 1917, 1984, 1985, 1998, 2000, 2011, 2012, and 2014.

By contrast, the seven coolest July months for afternoon temperatures on record, in chronological order are: 1918, 1929, 1935, 1939, 1963, 1965, and 1969.

The average afternoon temperature for Tauranga for July for 49 years from 1914-1962 was 14.0 degrees Celsius, compared with the average afternoon temperature for Tauranga for July for 49 years from 1963-2011 was 14.2 degrees Celsius.

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Climate Change – Gamekeeper or Poacher?
 
Weather Eye
with John Maunder

Among the many climate science meetings I've attended, the most significant – at least in terms of climate change is concerned – is my involvement in the UN-sponsored International Conference in Villach, Austria, in October 1985.

About 100 from 30 countries attended the meeting – in contrast to the 10,000-20,000 who now attend such meetings – and I was privileged to be the only New Zealander invited.

We were all there as experts – not representing our respective organisations or necessarily the views of our respective Governments – in various fields of science, endeavouring to do the best we could in looking at the complexities of climate science.

Among principal findings of this conference was: “while other factors, such as aerosol concentration, changes in solar energy input, and changes in vegetation, may also influence climate, greenhouse gases are likely to be the most important cause of climate change over the next century”.

At the time, even though I was partly responsible for the writing of the above paragraph, along with a few of my colleagues I had some misgivings about this phrase.

And I was somewhat surprised that within a year ‘human-induced global warming' caught the imagination of many around the world.

Today not a day goes by without some mention of global warming, climate change etc – all terms which up until 1980 were the preserve of academic text books along terms such as ‘emission trading schemes', which weren't even thought of until very recently.

Despite this concern, a colleague of mine from Australia, Bill Kininmonth, who in 2004 wrote an excellent book called ‘Climate Change - A Natural Hazard' has mentioned to me on several occasions I've changed from being the ‘gamekeeper' and become the ‘poacher'.

Whether this is true is a matter of opinion. However, irrespective of my personal views on the matter, it's clear there are two main views held by climate scientists and others on the subject of global warming and climate change.

Those mainly involved in the Intergovernmental Panel on Climate Change and many or most government scientists, plus others, such as Al Gore, many politicians and most journalists consider man, including domestic animals, is the prime cause of recent changes in the climate.

Then there's those – including some university scientists, several retired climatologists and climate scientists, and a minority of politicians and journalists, who consider nature is the main cause of changes in the climate

Twenty years ago it was unconceivable the New Zealand Government would have a Minister of Climate Change.

Back then, as weather forecasters and climatologists, we just got on with our job of making the best possible weather forecast and providing the best climate advice to all who requested information – without guidance or interference from the Government of the day.

How things have changed.



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Brisbane feels coldest morning in 103 years


Weather Eye
with John Maunder

Slightly unbelievable from the depths of winter in New Zealand – but it not always warm in Queensland.

Brisbane recorded its coldest morning in 103 years on July 13, 2014, with low temperatures also being felt across the rest of the Queensland state.

The Australian Bureau of Meteorology says the state's capital dropped to 2.6 degrees Celsius just before 7am. The bureau says it's been exceptionally cold.

Clermont in central Queensland had record-low temperatures on Friday, July 11, but broke records again on Saturday morning July 12, with the temperature dropping down to minus 4.5 degrees Celsius.

And the five coldest places were Oakley with minus six degrees Celsius, Warwick with 5.9 degrees Celsius, and Kingaroy minus 5.7 degrees Celsius.

In New South Wales, Glen Innes recorded a temperature of minus 11.3 degrees Celsius, while Thredbo recorded a low of minus 4.1 degrees Celsius.

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Global temperatures: January 1979-June 2014


Weather Eye
with John Maunder

The latest global average temperatures of the troposphere – those observed from National Oceanic and Atmospheric Administration satellites – are computed by the University of Alabama at Huntsville in the United States.

Of significance there appears to be very little change in the overall global temperatures during the last 15 years.

The chart shows since 1979, when reliable satellite observations have been available, there has been little overall trend.

However, that's except for a small warming trend from the average temperatures during the 30-year period from 1981-2010 in the temperatures in troposphere, apart from ‘normally expected' variations.

The data for 2011 is January 0.0 degrees Celsius, February -0.02, March -0.10, April +0.12, May +0.14, June +0.32, July +0.38, August +0.33, September +0.29, October +0.12, November +0.12, December +0.10 degrees.

The data for 2012 is: January -0.09 degrees, February -0.12, March +0.11, April +0.29, May +0.29, June +0.37, July +0.28, August +0.34 , November +0.28, December +0.20 degrees.

The data for 2013 is: January +0.50 degrees, February +0.18, March +0.20, April +0.10, May +0.07, June +0.30, July +0.17, August +0,16, September +0.37, October +0.29, November +0.19, December +0.23 degrees.

The data for 2014 is: January +0.29 degrees, February +0.17 degrees, March +0.17 degrees, April +0.19 degrees, May +0.33 degrees, and June +0.30 degrees Celsius.

The coolest months since 1979 were September 1984 with minus 0.49 degrees Celsius and November 1984 with minus 0.42 degrees Celsius.

The warmest months were February and April 1998, both 0.76 degrees Celsius.

The chart shows the El Nino warming in the 1998 period and the Mount Pinatubo, volcanic, cooling during 1992-1993.

- See more at: http://www.sunlive.co.nz/blogs/6830-global-temperatures-january-1979june-2014.html#sthash.fcCb2Kko.dpuf

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Tauranga’s Warmest (afternoon temperatures) in June in 100 Years


Weather Eye
with John Maunder

Temperatures have been recorded in the Tauranga area at several sites during the last 100 years, including at the current Tauranga Airport site from June 1990.

The graph shows details of the average daily maximum temperatures, called simply ‘afternoon', for Tauranga for June from 1913-2014.

The long-term average afternoon temperature in June for Tauranga is 14.7 degrees Celsius.

The cool' June months were in 1972 with 13.0 degrees Celsius, 1936 with 13.2 degrees Celsius, and 1933 with 13.3 degrees Celsius.

The ‘warm' June months include this year – 2014 – with 16.9 degrees Celsius, and 1916 and 2011, both with 16.6 degrees Celsius.

Last month's average temperature of 16.9 degrees Celsius is the warmest June on record since observations were first made in 1913.

The graph of the average afternoon temperatures for June shows generally ‘normal' variations from June to June during the last 100 years.

But many of the last 15 June months since 1996 have been a little ‘warmer' than other June months since 1913.

From 1913 to 2012, there have been 14 June months with an average afternoon temperature of 15.6 degrees Celsius or more, and 12 June months with an average afternoon temperature of less than 13.9 degrees Celsius.

The ninth ‘warmest' June months on record, in chronological order, are: 1916, 1971, 1981, 1998, 1999, 2002, 2003, 2011 and 2014.

By contrast, the seventh ‘coolest' June months on record, in chronological order, are 1933, 1936, 1941, 1944,1969, 1972 and 1976.

The average afternoon temperature in June during the period 1914-1962 was 14.7 degrees Celsius compared with 14.8 degrees Celsius from 1963 to 2011.

 


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Tauranga’s June rainfalls 1898-2014


Weather Eye
with John Maunder

The sixth wettest on record rainfall for the month of June have been recorded in Tauranga in 2014.

The graph shows the range of rainfalls from an extreme high of 381 mm in 1925 to a low of 19mm in 1906.

The second wettest June was 1920, when 309mm was recorded, and the second and third driest June months were in 1959 and 2012 when only 27mm fell.

The long-monthly average rainfall for Tauranga for June is 131 mm.

The graph of the June rainfall shows normal variations from year to year.

There is a small decrease in the overall June rainfalls during the last 50 years, form 1961-2010, from an average of 126mm, compared with an average of 139mm during the 50 years from 1911-1960.

Since 1898, there have been 17 June months with a rainfall of 200mm or more, and 10 June months with rainfalls of 50mm or less.

The rainfall for June 2014 was 229 mm, which made it the sixth wettest on record.

In chronological order the wettest 17 June months are: 1915, 1917, 1920, 1925, 1930, 1935, 1939, 1943, 1946, 1961, 1968, 1971, 1981, 1985, 1997, 2010, and 2014.

By contrast the driest June months in chronological order are: 1906, 1913, 1914, 1933, 1942, 1958, 1959, 1967, 2001, and 2012.

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 The Maunder Minimum and Sunspots


Weather Eye
with John Maunder

The ‘Maunder Minimum' is the name given to the period from 1645 to 1715 when the number of sunspots – ‘storms' on the sun – became almost zero.

The period is named after the solar astronomer Edward Walter Maunder (1851-1928), who was working at The Royal Observatory at Greenwich when he discovered the dearth of sunspots during this period.

During one 30-year period within the Maunder Minimum there were only about 50 sunspots compared with a more typical 40,000.


Photo image: Google.

Maunder was a driving force in the foundation of the British Astronomical Association and a fellow of the Royal Astronomical Society.

The sun was well observed during the period of the Maunder Minimum and this lack of sunspots is well documented.

This period of solar inactivity corresponded to a climatic period called the ‘Little Ice Age' when in Europe rivers that were normally ice-free, froze and snow fields remained at low altitudes throughout the year.

There is evidence the sun had similar periods of inactivity during the years 1100-1250 and 1460-1550.

Sunspots generally follow a cycle of about 11 years, but cycles have varied from eight-15 years.

The connection between solar activity and the earth's climate is an area of ongoing and sometimes controversial research.


Photo image: Google.

Time will tell whether the sun will once again go into another ‘Maunder Minimum' within the lifetime of the present generation, but if this happens we're likely have a much colder climate for a few decades.

A sunspot is a relatively dark, sharply defined region on the solar disc – marked by an umbra, dark area, which is 2000 degrees cooler than the effective photospheric temperature.

The average diameter of a sunspot is 4000km, but they can exceed 200,000km.

The NASA solar physics website, and other websites such as the Royal Observatory of Belgium, include information on sunspot numbers, the ‘Maunder Minimum' and sunspot cycle predictions.

The sunspot index is updated monthly and available from 1749.


Photo image: Google.

The last time the monthly sunspot number was above 100 during the last 14 years was in September 2002, when the value was 110. February 2014 had a sunspot value of 102.

The last time the value was above 200 was in August 1990, when the value was 200.3 – and there were no sunspots observed in September 2009. The value for May 2014 was 75.

For further information on climate matters, see:



Photo image: Google.

 

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Planet Earth – the last 420,000 years


Weather Eye
with John Maunder

There's an excellent website compiled and updated monthly by Dr Ole Hilum, who is a Danish professor of physical geography at the University of Oslo, and adjunct professor of physical geography at the University Centre in Svalbard.

You can check it out at: http://climate4you.com

His academic focus includes glacial and periglacial, geomorphology, and climatology. The following item is compiled from his website.

Planet Earth has an age of about 4600 million years.

Most, if not all, of geological divisions are based on the recognition of environmental changes affecting the entire planet. That is past global climate changes, which has been the rule for the entire history of Earth – not the exception.

If each year of the 4600 million years is represented by one millimetre, the entire period would be about 4600 kilometres long.

On this scale modern humans would appear within the last 200 metres, the polar bear within the last 150 metres, and the entire global meteorological record since about 1850 would take up the last 160mm.

From time to time the planet has been affected by millions of years with a relatively cold climate, each such period leading to a long succession of glacial and interglacial periods. During the last couple of millions of years, Earth has been in such a cold stage.

The last, until now, ice age ended about 11,600 years ago, and we're living in a so-called interglacial period, until the next ice age will begin sometime in the future.

The last four glacial periods and interglacial periods are shown in the diagram, covering the last 420,000 years in Earth's climatic history.

The reconstructed global temperature shown, which covers the last 420,000 years, is based on the Vostok ice core from Antarctica.

The records span during four glacial periods and five interglacials, including the present. The horizontal line indicates the modern temperature.

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Tauranga’s May Afternoon temperatures 1913-2014

Weather Eye
with John Maunder

Temperatures have been recorded in the Tauranga area at several sites during the last 100 years, including the current Tauranga Airport site from June 1990.

 

It is very common for areas such as Tauranga to have experienced different observation sites during the years; and the readings from the earlier sites have been adjusted to the present site using standard climatological procedures.

It is considered the temperature series described here is a fair and true record of what the temperature would have been if the current observation site (Tauranga Airport) had been used throughout the period.

Traditionally, temperature observations have been recorded with a set of maximum and minimum temperature thermometers.

These record the daily maximum temperature – usually recorded in mid-afternoon – and daily minimum temperature – usually recorded just before dawn.

The analysis of temperatures for Tauranga is for the average daily maximum temperatures.

The graph shows details of the average daily maximum temperatures, called simply ‘afternoon' from now on, for Tauranga for May from 1913-2014. May 1964 is not included because of incomplete data.

The long-term average afternoon temperature in May for Tauranga is 16.9 degrees Celsius, ranging from the cool May months of 1936, 1940, and 1997 with an average afternoon temperature of 14.9 degrees Celsius, to the warm May months of 1916 with 19.3 degrees Celsius, 2011 having 19.1 degrees Celsius and 2007 with 18.9 degrees Celsius.

The graph of the average afternoon temperatures for May shows generally normal variations from May to May.

However, the last 20 May months have been a little warmer than other since 1913.

From 1913 to 2014, there have been 13 May months with an average afternoon temperature of 18.0 degrees Celsius or more, and 11 May months with an average afternoon temperature of less than 16.0 degrees Celsius.

The value for May 2013 was 18.5 degrees Celsius, which is the fifth warmest on record and for May 2014 the temperature was 18.4 degrees Celsius – the sixth warmest on record.

The 13 warmest May months, in terms of afternoon temperatures, on record in chronological order are: 1916, 1928, 1938, 1950, 1999, 2000, 2003, 2005, 2007, 2010, 2011, 2013 and 2014.

In contrast, the 11 coolest May months, in terms of afternoon temperatures, on record in chronological order are: 1913, 1920, 1924, 1936, 1940, 1945, 1959, 1967, 1977, 1983, and 1992.

The average afternoon temperature in May during the 49-year period 1914-1962 was 16.7 degrees Celsius, compared with 17.1 degrees Celsius for the 49-year period from 1963-2011.

 


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Tauranga’s Fifth Driest May last month


Weather Eye
with John Maunder

Rainfalls for the month of May have been recorded in Tauranga since 1898 – except for 1904, 1907, 1908, and 1909 – and the city's fifth driest May occurred last month.

The graph shows the range of rainfalls from an extreme high of 634mm in 2005 to a low of 13mm in 2001. The rainfall for May 2014 is 28mm – the fifth driest May since records became available in 1898.

The second wettest May was 1950, when 311mm was recorded, and the second driest May was in 1918, when only 24mm fell. The long-term average rainfall for Tauranga for May is 124mm.

Apart from the exceptional rainfall of 634mm in May 2005, the graph shows a small decrease in overall May rainfalls when two 50-year periods are compared.

The average May rainfall of 127mm during the 50 years from 1911-1960 has dropped to 115mm during the five decades from 1961 to 2010.

Since 1898, there have been 14 May months with a rainfall of 200mm or more. In chronological order, the wettest May months are: 1899, 1900, 1917, 1925, 1926, 1928, 1949, 1950, 1956, 1961, 1962, 1971, 2005, and 2010.

In terms of dry May months, there have been only nine May months with rainfall of less than 40mm. In chronological order, the driest May months are: 1901, 1918, 1939, 1941, 1978, 1991, 1999, 2007, and 2014.

Of particular significance is the exceptional rainfall in May 2005. I estimate such a rainfall is likely to occur in Tauranga only about twice in every 1000 years.

This suggests central government could have had a much more important role in financial implications of the floods, which affected many areas of Tauranga in May 2005.

 


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Global Average Temperatures Observed from Satellites 1979-2013

Weather Eye
with John Maunder

Global average temperatures of the troposphere – those observed from NOAA satellites – are computed each month by the University of Alabama. Temperatures shown are deviations from the average for the 30-year period 1981 to 2010.

The chart shows that, since 1979, when reliable satellite observations have been available, there has been little significant changes in global temperatures in the troposphere (except for ‘normal’ variations), apart from a small warming trend.

The coolest months (since 1979), were September 1984 (-0.49 degrees) and November 1984 (-0.42 degrees), associated with the cooling from the Mount Pinatubo volcanic eruption.

The warmest months were February and April 1998 (both +0.76 degrees), associated with a very strong El Nino event.

 

For further information, see: https://sites.google.com/site/climatediceandthebutterfly

 

 

 

 

 

 

 

 

 

 

 

 

 

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  TAURANGA RAINFALLS OBSERVATIONS SINCE 1898

Weather Eye
with John Maunder

Monthly rainfalls for Tauranga have been recorded at several recording sites over the last 114 years.

From January 1898 to December 1904, the observation site was the Tauranga Harbour, from November 1904 to April 1907 the site was described as simply ‘Tauranga’, from January 1910 to December 1923 the site was Waikareao in Otumoetai, from January 1924 to September 1940 the site was at 148 Waihi Road in Judea, from October 1940 to January 1941 the site was at Te Puna, and from February 1941 to the present, the site is Tauranga Airport.

C.S Thompson of the former New Zealand Meteorological Service computed a homogeneous rainfall series for Tauranga appropriate to the current recording site at the airport.

The methodology use in adjusting the older sites to the current observing site is published in the NZ Meteorological Service Miscellaneous Publication No 180 in 1984.

Although adjusting rainfall observations from one site to another is not without its difficulties, it is considered that the homogeneous rainfall series described here is a fair and true record of what the rainfall would have been if the current observation site (Tauranga Airport) had been used since 1898, with the understanding that although standard accepted methodologies have been used, any adjustments are only estimates of what would have occurred if the location of the rainfall records had always been in the same place with the same surroundings and the same or similar recording gauge.

In terms of climate change, (such as: is it getting wetter or drier, or warmer or colder?) the methodology used in computing an ‘official’ set of climate observations is very important as otherwise erroneous conclusions may be drawn.

The long-term average rainfall for Tauranga for the calendar year is 1300mm, ranging from a low of 747mm in 2002, to 2049mm in 1962.  

For comparison, the rainfall for the past year, 2011, was 1696mm, which made it the ninth wettest year since observations began in 1898.

Since 1898, there have been only three years with a rainfall of less than 1000mm (1993, 1982, 2002), and only three years with a rainfall over 1800mm (1938, 1917, 1916). 

The 10 wettest years on record are: 1962 (156% of the long term average), 1916 (147%), 1917 (143%), 1938 (138%), 1920 (136%), 1956 (135%), 1971 (133%), 1979 (131%), 2011 (129%), and 2005 (128%).

In chronological order these wettest years occurred in 1916, 1917, 1920, 1938, 1956, 1962, 1971, 1979, 2005 and 2011.

In contrast the 10 driest years on record are: 2002 (57% of the long term average), 1915 (59%), 1982 (64%), 1993 (66%), 1906 (72%), 1919 (73%), 1997 (74%), 1973 (75%), 1986 (75%), and 1999 (76%).

In chronological order these driest years occurred in 1906, 1915, 1919, 1973, 1982, 1986, 1993, 1997, 1999, and 2002.

A graph of the rainfalls for Tauranga for 1898-2011 shows little long-term change although the last three decades have shown some tendency towards drier years, with five of the driest 10 years occurring during the last 30 years.

However, two of wettest 10 years have occurred during the last decade.

 

Dr John Maunder is a retired climate scientist now living in Tauranga. He was President of the Commission for Climatology of the World Meteorological Organization (WMO) from 1989 to 1997. Over the last 60 years he has written four books and has been involved in the ‘weather business’ in various countries, including New Zealand, Australia, Canada, USA, Ireland, Switzerland, and the UK.

For further information, Google ‘Dr John Maunder’ or email climate@ihug.co.nz

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 NO TREND in TAURANGA FEBRUARY RAINFALLS: 1898-2011

Weather Eye
with John Maunder

Rainfalls for the month of February have been recorded in Tauranga since 1898 (except for 1904,1908,and 1909).

The graph show the range of rainfalls from a high of 343 mm in 1936 to a low of 7 mm in 1973. The long-term average rainfall for Tauranga for February is 90 mm. The graph show no significant overall trend in the rainfalls in February over the last 110 years apart from a small decrease the average rainfall from 95 mm in the 50 years ending in 1960 to 86 mm in the 50 years to 2010.

Since 1898 there have been 11 February months with rainfall of 200 mm or more, and 15 February  months with a rainfall of more than double the average. In contrast, 10 February months have had  rainfall of 10 mm or less, including both 2010 and 2011.  

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The Maunder Minimum: Changing spots on the Sun

Weather Eye
with John Maunder

The ‘Maunder Minimum’ is the name given to the period from 1645 to 1715 when the number of sunspots – ‘storms’ on the sun – became almost zero. 

The period is named after the solar astronomer Edward Walter Maunder (1851-1928) who, while working at The Royal Observatory at Greenwich, discovered the dearth of sunspots during this period.

During one 30-year period within the Maunder Minimum there were only about 50 sunspots compared with a more typical 40,000. Maunder was a driving force in the foundation of the British Astronomical Association and was a Fellow of the Royal Astronomical Society. 

The sun was well observed during the period of the Maunder Minimum and this lack of sunspots is well documented. This period of solar inactivity corresponded to a climatic period called the ‘Little Ice Age’ when rivers that are normally ice-free, froze and snow fields remained at low altitudes throughout the year. There is evidence the sun had similar periods of inactivity during the years 1100 to 1250 and 1460 to 1550. 
Sunspots generally follow a cycle of about 11 years, but cycles have varied from 8 to 15 years. The connection between solar activity and the earth’s climate is an area of on-going and sometimes controversial research. Time will tell whether the sun will once again go into another ‘Maunder Minimum’ within the lifetime of the present generation.
A sunpot is a relatively dark, sharply defined region on the solar disc – marked by an umbra (dark area) which is 2000 degrees cooler than the effective photospheric temperature. The average diameter of a sunspot is 4000km, but can exceed 200,000km. 

The NASA Solar Physics website includes information on sunspot numbers, the ‘Maunder Minimum’ and sunspot cycle predictions. The  sunspot index is updated monthly and available from 1749. The last time the monthly sunspot number was above 100 was September 2002 when the value was 109.6 and the last time the value was above 200 was in August 1990 when the value was 200.3. No sunspots were observed in September 2009.

 

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MARCH RAINFALLS in TAURANGA: 1898-2011

Weather Eye
with John Maunder

Rainfalls for the month of March have been recorded in Tauranga since 1898 – except for 1904, 1908, and 1909.

This graph shows the range of rainfalls from a high of 504mm in 1979, to a low of 5mm in 1943. The second wettest March was 1972 when 319mm was recorded, and two March months – 1910 and 2010 – recorded only 14mm. The long-term average rainfall for Tauranga for March is 110 mm.

The graph shows no significant overall trend in the rainfalls in March during the last 110 years, apart from a small increase in the average rainfall from 103mm in the 50 years ending in 1960, to 117mm in the 50 years to 2010. This can be compared with the months of January and February during the same 50 years, which both show a small decrease: In January, falls from 86mm to 81mm, and in February from 95mm to 86mm. Since 1898, there have been 11 March months with a  rainfall of 200mm or more – the same as the number of months in February with more than 200mm –and six March months have had  rainfall of 20mm or less.

 

CLIMATE EXTREMES IN NEW ZEALAND

Weather Eye
with John Maunder

Climate extremes in New Zealand, since instrumental records became available in the 1850s, show a range from the highest temperature of 42.4 degrees C recorded in Rangiora on February 7, 1973, to the most intense rainfall in 10 minutes of 34 mm which occurred in Tauranga on April 17, 1948. 

Each year, the National Institute of Water and Atmospheric Research updates the weather extremes recorded in New Zealand since observations were officially recorded in the 1850s. The current extremes – up to December 2010 – include the following: 

Wettest: 34mm in 10 minutes in Tauranga on April 17 1948. 134mm in one hour in the Hokitka Catchment. This site also has the records for the highest 24 hours fall of 758mm on December  27/28, 1989, the highest 48 hour fall of 1049mm on December 11/12/13, 1995, the highest fall in a calendar month of 2827mm in December 1995, and the highest fall in a calendar year of 16,617mm in 1998.  

Driest: Only 9mm of rain fell at Cape Campbell (Marlborough) from January to March 2001, the driest three-months ever recorded in New Zealand. The driest six months was also at Cape Campbell from November 2000 to April 2001 when only 52mm of rain was recorded. The driest 12 months was in Alexandra from November 1963 to October 1964, when only 167mm was recorded. The longest period without rain is 71 days, which occurred in Wai-iti, Marlbough from February 8 1939.  

Warmest: Until 1973, the highest temperatures officially recorded in New Zealand was 101.3 degrees Fahrenheit (38.4 degrees Celsius) at Ashburton and Darfield on January 19, 1956. However, under extreme northwesterly conditions on February 7, 1973, 42.4 degrees C (108.3 degrees Fahrenheit) was recorded at Rangiora. A temperature of 42.3 degree C was also recorded on this day at Jordan, Marlborough.

Coldest: The coldest air temperature ever recorded was -25.6 degrees C in Eweburn, Ranfurly on July 17, 1903. The lowest grass temperature is -21.6 degrees C recorded at Lake Tekapo on August 4, 1938.

Sunniest: Nelson, Takaka, Riwaka, Blenheim, Lake Tekapo, Tauranga and Whakatane often appear in the list of very sunny places in New Zealand, but officially, Nelson has recorded the most sunshine in any one year with 2711 hours in 1931, with Blenheim recording 2673 hours in 1961. In contrast, only 1333 hours of sunshine was recorded in Invercargill in 1983. For one month, the sunniest location is Nelson with 336 hours in December 1934, and the least sunny location is Taumaranui with only 27 hours in June 2002.  

Wind Gust: The highest wind gusts recorded in New Zealand were 250 km/h at Mt John, Canterbury on April 17, 1970 and 248 km/h at Hawkins Hill, Wellington on November 6, 1959, and July 4, 1962.

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 Tauranga April Rainfalls 1898-2011
 
 
Weather Eye
with John Maunder

Rainfalls for the month of April have been recorded in Tauranga since 1898 (except for 1904, 1908 and 1909).

The graph shows the range of rainfalls from a high of 383mm in 1911 to a low of 10mm in 1958.

The second wettest April was 1948 when 333mm was recorded, and April 2010 recorded only 12mm. The long-term average rainfall for Tauranga for April is 120mm.

The graph show no significant change in the rainfalls in April over the last 110 years except for small decease in the rainfall over the last 50 years compared with the first 50 years of the record from 133mm to 110mm.

This can be compared with the months of January and February and March over the same 110 years which show small decreases in the January and February and a small increase in March. Since 1898, there have been 17 April months with a rainfall of 200mm or more, but only eight April months with rainfalls of 30mm or less. 

 

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Climate change and Villach – what is the connection?

Weather Eye
with John Maunder

Among the many climate science meetings I have attended, the most significant, at least in term of climate change is concerned, is my involvement in the UN sponsored International Conference held in the beautiful town Villach, in Austria in October 1985.

One hundred experts from 30 countries attended the meeting (in contrast to ten to twenty thousand who now attend such meetings), and I was privileged to be the only New Zealander invited. We were all there as experts - and not representing our respective organisations - in various fields of science, endeavouring to do the best we could in looking at the complexities of climate science. 

Among the principal findings of this conference was that "while other factors, such as aerosol concentration, changes in solar energy input, and changes in vegetation, may also influence climate, the greenhouse gases are likely to be the most important cause of climate change over the next century”.

At that time, even though I was partly responsible for the writing of the above paragraph, I along with a few of my colleagues, had some misgivings about this phrase, and were somewhat surprised that within a year ‘human-induced global warming’ caught the imagination of much of the world. Indeed today, not a day goes by without some mention of ‘global warming’, climate change, emission trading schemes, etc, all terms which up until 1980 were the preserve of academic text books, as well as terms such as ‘emission trading schemes’, which were not even thought of until very recently.

Despite this concern, a colleague of mine from Australia, Bill Kinninmonth, who in 2004 wrote a book called "Climate Change - A Natural Hazard" has mentioned to me on several occasions that I have changed from being the ‘gamekeeper’ and become the ‘poacher’. Whether that is true is a matter of opinion. However, irrespective of my personal views on the matter, it is clear that there are two main views held by climate scientists and others on the subject of global warming and climate change.

First, those who are mainly involved in the Intergovernmental Panel on Climate Change and many or most government scientists, plus others, such as Al Gore, and many politicians and most journalists who consider that man, including domestic animals, is the prime cause of recent changes in the climate;

Second, those - in the main some university scientists, many retired climatologists, and a minority of politicians and journalists, who consider that nature is the main cause of changes in the climate.

Twenty years ago, it was inconceivable that the New Zealand Government would have a Minister of Climate Change; indeed back then, as weather forecasters and climatologists we just got on with our job of making the best possible weather forecast and providing the best climate advice to all those who requested information, without guidance or interference from the Government of the day. How things have changed!

 

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Tauranga May rainfalls: 1898-2011

Weather Eye
with John Maunder

Rainfalls for the month of May have been recorded in Tauranga since 1898 (except for 1904, 1907, 1908, and 1909).

The graph shows the range of rainfalls from an extreme high of 634mm in 2005 to a low of 13mm in 2001. The second wettest May was 1950 when 311mm was recorded, and the second driest May was in 1918 when only 24mm fell. The long-term average rainfall for Tauranga for May is 124mm.

Apart from the exceptional rainfall of 634mm in May 2005 (such a rainfall in Tauranga in May is likely to occur only about twice every 1000 years), the graph show a small decrease in the overall May rainfalls over the last 50 years (1961-2010) from an average of 115mm, compared with an average of 126mm over the 50 years from 1911-1960.

This is similar to the months of January and February and April for the same periods, which also show small decreases in the overall rainfalls during the last 100 years, compared with a small increase in the March rainfalls.

Since 1898, there have been 14 May months with a rainfall of 200mm or more, but only four May months with rainfalls of 30mm or less.

 

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Global Annual Temperatures: 1880-2012

Weather Eye
with John Maunder

Global annual temperatures for various areas including global (land-ocean), global (meteorological stations), three latitude bands, and hemispheric, are prepared by the Goddard Institute for Space Studies of NASA. 

The global temperature graph shows little change in global temperatures since 2000. This compares with little change from 1880 to about 1910, a general warming from 1910 to the early 1940s, a cooling from the early 1940s to the mid 1970s, a warming from the mid 1970s to about 2000, and little change during the last decade.

The likely causes of the cooling and the warming periods during the last 130 years are a combination of natural events (including solar activity,  volcanic activity, and ocean currents) and the increases in human induced and animal induced greenhouse gases. These and other causes of climate change will be discussed in a later WeatherEye.

Since 1880, when comparative instrumental temperature records are available, the four coldest years according to the NASA site are 1890 and 1917 (both 0.39 degrees below the 1951-80 average), and 1877 and 1909 (both 0.35 degrees below the 1950-1980 average), and the four warmest years are 2010 (0.63 degrees above the 1951-80 average), 2005 (0.62 degrees above the 1951-80 average), and 1998 and 2007 (both 0.58 degrees above the 1950-80 average). The graph shows an increase in the global annual temperature, during the last 130 years, of about 0.8 degrees C. Some nations, and some people, may find this as either a risk, or an opportunity, or both. The implications of this will be discussed in a later WeatherEye.

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Tauranga: June Rainfalls 1898-2011

 

Tauranga June rainfalls 1898-2011
Weather Eye
with John Maunder

Rainfalls for the month of June have been recorded in Tauranga since 1898 (except for 1904, 1907, 1908, and 1909).

The graph shows the range of rainfalls from an extreme high of 381mm in 1925 to a low of 19mm in 1906. The second wettest June was 1920, when 309mm was recorded, and the second driest June was in 1959 when only 27mm fell. The long-term average rainfall for Tauranga for June is 131mm.

The graph of the June rainfall shows ‘normal’ variations form year to year. There is a small decrease in the overall June rainfalls during the last 50 years (1961-2010) from an average of 126mm, compared with an average of 139mm during the 50 years from 1911-1960. This is similar to the months of January, February, April, and May for the same periods, which also show small decreases in the overall rainfalls during the last 100 years, compared with a small increase in the March rainfalls. Since 1898, there have been 16 June months with a rainfall of 200mm or more, but only five June months with rainfalls of 40mm or less.

 

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Are we getting warmer or not?

Weather Eye
with John Maunder

Global temperatures are compiled for various areas including global (land-ocean), global (meteorological stations), three latitude bands, and hemispheric, by the Goddard Institute for Space Studies of NASA.

A graph of the global temperatures since 1890 shows a general warming from 1910 to the early ‘40s, a cooling from the early ‘40s to the mid ‘70s,  and a general warming from the mid ‘70s to about 2000. However since then, global monthly temperatures have been relatively steady with no real cooling or warming.

The yearly global temperatures (expressed as differences from the 1951-80 average) since 1998 are:  1998,  +0.58 degrees; 1999, +0.33; 2000, +0.35; 2001, +0.48; 2002, +0.56; 2003, +0.56; 2004, +0.49; 2005, +0.62; 2006, +0.55; 2007 +0.58; 2008, +0.44, 2009, +0.57 ;  2010, +0.63 ; and 2011, +0.51 degrees.  

The graph shows the monthly mean global surface temperature anomaly from the base period 1951-1980. The black line shows meteorological stations only; the dotted line is the land-ocean temperature index obtained from satellite measurements.

Global temperatures are compiled for various areas including global (land-ocean), global (meteorological stations), three latitude bands, and hemispheric, by the Goddard Institute for Space Studies of NASA.

A graph of the global temperatures since 1890 shows a general warming from 1910 to the early ‘40s, a cooling from the early ‘40s to the mid ‘70s,  and a general warming from the mid ‘70s to about 2000. However since then, global monthly temperatures have been relatively steady with no real cooling or warming.

The yearly global temperatures (expressed as differences from the 1951-80 average) since 1998 are:  1998,  +0.58 degrees; 1999, +0.33; 2000, +0.35; 2001, +0.48; 2002, +0.56; 2003, +0.56; 2004, +0.49; 2005, +0.62; 2006, +0.55; 2007 +0.58; 2008, +0.44, 2009, +0.57 ;  2010, +0.63 ; and 2011, +0.51 degrees.  

The graph shows the monthly mean global surface temperature anomaly from the base period 1951-1980. The black line shows meteorological stations only; the dotted line is the land-ocean temperature index obtained from satellite measurements.

Global temperatures are compiled for various areas including global (land-ocean), global (meteorological stations), three latitude bands, and hemispheric, by the Goddard Institute for Space Studies of NASA.

A graph of the global temperatures since 1890 shows a general warming from 1910 to the early ‘40s, a cooling from the early ‘40s to the mid ‘70s,  and a general warming from the mid ‘70s to about 2000. However since then, global monthly temperatures have been relatively steady with no real cooling or warming.

The yearly global temperatures (expressed as differences from the 1951-80 average) since 1998 are:  1998,  +0.58 degrees; 1999, +0.33; 2000, +0.35; 2001, +0.48; 2002, +0.56; 2003, +0.56; 2004, +0.49; 2005, +0.62; 2006, +0.55; 2007 +0.58; 2008, +0.44, 2009, +0.57 ;  2010, +0.63 ; and 2011, +0.51 degrees.  

The graph shows the monthly mean global surface temperature anomaly from the base period 1951-1980. The black line shows meteorological stations only; the dotted line is the land-ocean temperature index obtained from satellite measurements.

 

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Tauranga July rainfalls 1898-2011

Weather Eye
with John Maunder

Rainfalls for the month of July have been recorded in Tauranga since 1898, except for 1904, 1907, 1908, and 1909.

The graph shows the range of rainfalls from an extreme high of 348mm in 1951 to a low of only 2mm in 1902. The second wettest July was 1998 when 315mm was recorded, and the second driest July was in 1983 when only 22mm fell. The long-term average rainfall for Tauranga for July is 129mm.

The graph of the July rainfall shows ‘normal’ variations from year to year. There is a very small decrease in the overall July rainfalls during the last 50 years (1961-2010) from an average of 127mm, compared with an average of 132mm during the 50 years from 1911-1960. This is similar to the months of January, February, April, May, and June during the same periods, which also show small decreases in the overall rainfalls during the last 100 years, compared with a small increase in the March rainfalls. Since 1898, there have been 12 July months with a rainfall of 200mm or more, but only two July months with rainfalls of 30mm or less. Interestingly, there have been two occasions in July when rainfalls of more that 200mm occurred in adjacent years (1979, 1978 and 2007, 2009).

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England: winters of the last 2000 years

Weather Eye
with John Maunder

If you are feeling the cold this winter, you might be thankful that you were not around in England in 1565, when the Thames was frozen solid between Christmas Day and January 13 and Queen Elizabeth I enjoyed daily trips on the ice.

This comment by reporter Andy Bloxham writing in UK newspaper the Daily Telegraph  on December 26, 2011, as well as the following extracts from the work of retired UK meteorologist Jim Rothwell, shows that at least in England there is really, to quote Ecclesiastes “...nothing new under the sun”.

Mr Rothwell, 80, has compiled The Central England Weather Series, which begins at 56BC in the era of Julius Caesar and is housed with Nottinghamshire County Council’s archives service. His sources, which number more than 50, range from county council and university archives to historical reference works, particularly those with pictures showing the weather in detail; to the writing of Samuel Pepys and John Evelyn, the 17th century diarists. He also used local newspapers to corroborate information and the library of De Bilt, in Holland, to get weather reports for the Middle Ages.

Using a wide variety of sources, Jim Rothwell has built what he believes to be the fullest study of weather across central England in existence. He has found striking examples of extreme weather going back hundreds of years.

For example, in 1357, after a dry early summer, then downpours throughout the autumn, winter saw starving wolves prowling through Sherwood Forest taking livestock and even threatening humans; the winter of 1458 saw a bridge destroyed over the river Trent because of floodwaters caused by melting ice which followed prolonged and heavy snowfall; and in 1635, severe blizzards led to very deep snow with drifts up to 6m deep in Lincolnshire.

However, Rothwell also found evidence of particularly mild winters. For example, in 1607, in the reign of James I, flowers were reported to be in bloom on Christmas Day; in 1249, witnesses claimed the winter was so mild that there were “birds singing like it was spring”. The summer of 1375 is also noteworthy, as evidence shows the warm, dry weather lasted well into October;  the rainy summer of 1315, which was so wet  on July 15 that it is thought to be the origin of the St Swithin’s Day belief that if it rains on that day, it will continue for 40 more;  and 1258, a wet and cool summer, leading to the failure of the crops and an appalling winter famine  which was one of the worst in English history, with 20,000 people starving to death in London alone, and reports of people driven to eat the bark off trees. Further, in 1635 in Gainsborough, Lincolnshire, eight young men drowned in winter when skating on a Sunday in what was known locally as the Divine Tragedy, as it was thought their deaths were a punishment for skating on a holy day.

For most Londoners, holding fairs and roasting oxen on thick ice on the River Thames today is unimaginable. In centuries past, though, it could and was done whenever there was a particularly cold spell. The first recorded Frost Fair was held in 1564 and Londoners danced and practised archery on the ice.

On December 23rd 1683, the diarist John Evelyn describes “a greate frost”. By January 1st 1684, the ice being so thick that booths were set up on the Thames. A few days later, he crossed the river on foot and saw streets of booths selling all kinds of wares and a whole ox was even roasted on the ice. 

During the winter of 1739-40 the frost began on Christmas Day and continued until February 17th and was known as the Great Frost. The last great Frost Fair held on the River Thames in 1813-14. The watermen, who usually earned a living by ferrying people across the river, replaced their lost earnings by charging people for entering the fair. The frost fairs came to an end when the flow of the river was increased by the demolition of the old London Bridge and the opening of the new London Bridge in 1831.

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Tauranga August rainfalls 1898-2011

Weather Eye
with John Maunder

Rainfalls for the month of July have been recorded in Tauranga since 1898 (except for 1904, 1907, 1908, and 1909).

 

The graph shows the range of rainfalls from an extreme high of 274mm in 2010 to a low of only 17mm in 1914. The second wettest July was 1916 when 263mm was recorded, and the second driest July was in 1982 when only 31mm fell. The long-term average rainfall for Tauranga for August is 124mm.

The graph of the August rainfall shows normal variations from year to year. There is a small decrease in the overall August rainfalls during the last 50 years (1961-2010)  from an average of 121mm, compared with an average of 133mm during the 50 years from 1911-1960. This is similar to the months of January, February, April, May, June and July over the same periods, which also show small decreases in the overall rainfalls during the last 100 years, compared with a small increase in the March rainfalls.

Since 1898, there have been 15 August months with a  rainfall of 200mm or more (14 of which occurred during the period 1900 to 1976, and only one August month since then), but only two August months with a rainfalls of 40mm or less. 

 

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Tauranga September rainfalls 1898-2011

Weather Eye
with John Maunder

Rainfalls for the month of September have been recorded in Tauranga since 1898, except for 1904, 1907, 1908, and 1909.

The graph shows the range of rainfalls from an extreme high of 274mm in 1973 to a low of only 16mm in 1965. The second wettest September was 1900 when 256mm was recorded, and the second driest September was in 1944 when only 27mm fell. The long-term average rainfall for Tauranga for September is 106mm.

The graph of the September rainfall shows normal variations from year to year. There is a very small decrease in the average of the September rainfalls during the last 50 years (1961-2010) from an average of 103mm, compared with an average of 105mm during the 50 years from 1911-1960. This is similar to the months of January, February, April, May, June, July and August during the same periods, which also show small decreases in the overall rainfalls during the last 100 years, compared with a small increase in the March rainfalls. Since 1898, there have been five September months with a  rainfall of 200mm or more (four of which occurred during the period 1900 to 1928, and only one September month since then), compared with six September months with a rainfalls of 40mm or less. 

 

For further information, Google "Dr John Maunder".

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February rainfalls 1898-2013

Weather Eye
with John Maunder

Rainfalls for the month of February have been recorded in Tauranga since 1898 (except for 1904,1908, and 1909).

The graph shows the range of rainfalls from a high of 343 mm in 1936 to a low of only 7 mm in 1973 and 2011.


Four February months have had a rainfall of less than 10mm and this compares with a total of 34 in the February of 2013. The second wettest February was 2001 when 268 mm was recorded. The long-term average rainfall for Tauranga for February is 82mm.

The graph of the February rainfalls (from 1898 to 2012) shows "normal" variations from year to year. By adding the February 2013 rainfall of 34mm does not change anything in the way of any significant change in the overall pattern of February rainfalls.

There is a small decrease in the overall February rainfalls over the last 50 years (1961-2010) from an average of 86 mm, compared with an average of 95 mm over the 50 years from 1911-1960.

This is similar to the months of January, April, May, June, July, August, September, October, and November over the same periods which also show small decreases in the overall rainfalls over the last 100 years, compared with a small increase in the March and December rainfalls.

For further information Google "Dr John Maunder"

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Tauranga Temperatures 1913-2012

Weather Eye
with John Maunder

Tauranga Temperatures 1913-2012

Temperatures have been recorded in the Tauranga area at several sites in the last 100 years including the current Tauranga Airport site from June 1990.


It is very common for areas such as Tauranga to have had different observation sites over the years and the readings from the earlier sites have been adjusted to the present site using "standard climatologically procedures".

It is considered that the temperature series described here is a fair and true record of what the temperature would have been if the current observation site (Tauranga Airport) had been used throughout the period.

It is important to note, that in considering “climate change”, the methodology used in computing an ‘official’ set of climate observations is very important as otherwise erroneous conclusions may be drawn.

Traditionally, temperature observations have been recorded with a set of maximum and minimum temperature thermometers. These record the daily maximum temperature (usually recorded in mid-afternoon), and daily minimum temperature (usually recorded just before dawn).

This analysis of temperatures for Tauranga are those for the average daily maximum temperatures. Later analyses will be for the average daily minimum temperatures.

The graph shows details of the average daily maximum temperatures (called simply "afternoon" from now on), for Tauranga from 1913-2011. Note that the years of 1942,1943,1947,1957,and 1964 are not included because of incomplete data.

The long-term average afternoon temperature for Tauranga for is 19.0 degrees C. ranging from the "cool" years of 1976 and 1992 with an average afternoon temperature of 18.1 degrees C , and 1923 with an average afternoon temperature of 18.2 degrees C, to the "warm" years of 1916 (20.1 degrees C),1998 (20.0 degrees C), and 2010 (19.9 degrees C).

The graph of the average afternoon temperatures shows generally "normal" variations from year to year with the earlier years of the record (1914, 1915, 1916), and in particular the last few years (1998, 1999, 2010, 2011) being notably "warmer" than other years.

From 1914 to 2011, there have been 15 years with an average afternoon temperature of 19.5 degrees or more, and 18 years with an average afternoon of 18.6 degrees or less.

The value for 2012 was 19.4 degrees. The 11 "warmest" years ( in terms of afternoon temperatures) on record, in chronological order, are 1914, 1915, 1916, 1928, 1938, 1998, 1999, 2005, 2010, 2011, and 2012. In contrast the 10 "coolest" years (in terms of afternoon temperatures) on record, in chronological order, are 1918,1920,1923,1941,1945,1965,1976,1977,1980, and 1992.

For further information

Google “Dr John Maunder”

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March Afternoon Temperatures 1913-2013

Weather Eye
with John Maunder

Temperatures have been recorded in the Tauranga area at several sites over the last 100 years including the current Tauranga Airport site from June 1990.

It is very common for areas such as Tauranga to have had different observation sites over the years and the readings from the earlier sites have been adjusted to the present site using "standard climatologically procedures".


It is considered that the temperature series described here is a fair and true record of what the temperature would have been if the current observation site (Tauranga Airport) had been used throughout the period.

It is important to note, that in considering “climate change”, the methodology used in computing an ‘official’ set of climate observations is very important as otherwise erroneous conclusions may be drawn.

Traditionally, temperature observations have been recorded with a set of maximum and minimum temperature thermometers. These record the daily maximum temperature (usually recorded in mid-afternoon), and daily minimum temperature (usually recorded just before dawn).

This analysis of temperatures for Tauranga are those for the average daily maximum temperatures. Later analyses will be for the average daily minimum temperatures.

The graph shows details of the average daily maximum temperatures (called simply "afternoon" from now on), for Tauranga for March from 1913-2012.

Note that March 1947 is not included because of incomplete data. The long-term average afternoon temperature in March Tauranga for is 22.5 degrees C, ranging from the "cool" March months of 1960 with an average afternoon temperature of 20.4 degrees C , and 1940 with an average afternoon temperature of 20.8 degrees C, to the "warm" March months of 1916 (24.7 degrees C), and 1938 and 1968 (24.6 degrees C).

The graph of the average afternoon temperatures for March shows generally "normal" variations from March to March with the earlier years of the record (1913, 1914, 1916), and the late 1990’s (1998,1999, 2002), being notably "warmer" than other March months.

From 1914 to 2012, there have been 13 March months with an average afternoon temperature of 23.6 degrees or more, and 11 years with an average afternoon temperature of 21.0 degrees or less.

The value for March 2013 was 24.1 degrees which shows that it was the fifth equal warmest March month since records began in 1913.

The 10 "warmest" March months ( in terms of afternoon temperatures) on record, in chronological order, are 1913, 1916, 1938,1948,1955,1968,1990, 2005, 2010 and 2013. In contrast the 10 "coolest" March months (in terms of afternoon temperatures) on record, in chronological order, are 1923,1934,1936,1940,1945,1949,1960,1974,1992, and 1998.

The average afternoon temperature For March for the 48 years from 1914-1962 was 22.4 degrees C, compared with an average of 22.6 degrees for the 48 years from 1963-2011.

This small warming over the last 96 years is similar to warming in the months of January, February, April, May, June, July and August , compared with slight cooling in the months of September, October, November and December.

For further information Google “Dr John Maunder” or https://sites.google.com/site/climaterisksandbenefits/.

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Tauranga April Rainfalls 1898-2013

April 2013: Third wettest rainfall

Weather Eye
with John Maunder

Rainfalls in Tauranga in the month of April were the third wettest since records began in 1898.


The graph shows the range of rainfalls from a high of 383mm in 1911 to a low of 10mm in 1958.

The rainfall for April 2013 was 286mm - a “near record” rainfall showing that sometimes a “near record” wet month sometimes hides a very dry first two or three weeks of the month.

The second wettest April was 1948 when 333mm was recorded, and the second driest was April 2010 with only 12mm. The long-term average rainfall for Tauranga for April is 120mm.

The graph show a small decease in the rainfall over the last 50 years compared with the first 50 years of the record from 133mm to 110mm.

This can be compared with the months of January, February and March over the same 110 years showing small decreases in the January and February, and a small increase in March. Since 1898, there have been 17 April months with a rainfall of 200mm or more, but only eight April months with rainfalls of 30mm or less.

For further information Google ”Dr John Maunder” or log onto https://sites.google.com/site/climaterisksandbenefits/

 

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Third warmest April on record in Tauranga

Weather Eye
with John Maunder

Temperatures have been recorded in the Tauranga area at several sites over the last 100 years including the current Tauranga Airport site from June 1990.

It is very common for areas such as Tauranga to have had different observation sites over the years and the readings from the earlier sites have been adjusted to the present site using "standard climatologically procedures".

It is considered that the temperature series described here is a fair and true record of what the temperature would have been if the current observation site (Tauranga Airport) had been used throughout the period.

It is important to note, that in considering “climate change”, the methodology used in computing an ‘official’ set of climate observations is very important as otherwise erroneous conclusions may be drawn.

Traditionally, temperature observations have been recorded with a set of maximum and minimum temperature thermometers. These record the daily maximum temperature (usually recorded in mid-afternoon), and daily minimum temperature (usually recorded just before dawn).

This analysis of temperatures for Tauranga are those for the average daily maximum temperatures. Later analyses will be for the average daily minimum temperatures.

The graph shows details of the average daily maximum temperatures (called simply "afternoon" from now on), for Tauranga for April from 1913-2012. Note that April 1947 and 1964 are not included because of incomplete data.

The long-term average afternoon temperature in April for Tauranga for is 20 degrees C, ranging from the "cool" April months of 1925 with an average afternoon temperature of 18.2 degrees C , and 1923 with an average afternoon temperature of 18.3 degrees C, to the "warm" April months of 1938 (22.5 degrees C), and 1916 (22.4 degrees C).

The graph of the average afternoon temperatures for April shows generally "normal" variations from April to April with 1920’s  and the last 15 Aprils being a little "warmer" than other April months. From 1913 to 2012, there have been 12 April months with an average afternoon temperature of 21degrees or more, and eight April months with an average afternoon temperature of less than 19degrees.

The value for April 2013 was 21.5 degrees, the third warmest on record.

The 12 "warmest" April months (in terms of afternoon temperatures) on record, in chronological order, are 1916, 1924,1928, 1935,1938,1948,1955, 1956,1978, 1981, 2012, and 2013. In contrast, the 8 "coolest" April months (in terms of afternoon temperatures) on record, in chronological order, are 1923,1925,1940,1941,1949,1980,1991, and 1992.

For further information Google “Dr John Maunder” or log onto https://sites.google.com/site/climatediceandthebutterfly/

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Sunspots and the Maunder butterfly

Weather Eye
with John Maunder

The "Maunder Minimum" is the name given to the period from 1650 to 1700 when the number of sunspots (solar storms) became almost zero. 

The period is named after the solar astronomer Edward Walter Maunder (1851-1928) who while working at The Royal Observatory, Greenwich discovered the dearth of sunspots during the 1650-1700 period.

During one 30 year period within the Maunder Minimum there were only about 50 sunspots compared with a more typical 40,000. This period coincided with an extremely cold period in Europe.

Maunder was a driving force in the foundation of the British Astronomical Association, and was a Fellow of the Royal Astronomical Society.

Throughout the solar cycle (of about 11 years) the latitude of sunspot occurrences varies with an interesting pattern. The chart shows the latitude of sunspot occurrence versus time (in years).

Sunspots are typically confined to an equatorial belt (on the sun) between 35 degrees south and 35 degrees north latitude. At the beginning of a new solar cycle, sunspots tend to form at high latitudes, but as the cycle reaches a maximum (that is, a large numbers of sunspots) the spots form at lower latitudes.

Near the minimum of the cycle, sunspots appear even closer to the equator, and as a new cycle starts again, sunspots again appear at high latitudes. This recurrent behaviour of sunspots gives rise to the “butterfly'' pattern shown.

The reason for this sunspot migration pattern, understanding this pattern and how the Sun's internal magnetic field is generated, as well as the connection between solar activity and terrestrial climate is a continuing area of research.

Time will tell whether the sun will once again go into another Maunder Minimum within the lifetime of the present generation and what affect it will have on our climate.

The Maunder Butterfly diagram shows the position of sunspots since 1950 and shows that these sunspots first form at mid-latitudes and then widen and move towards the solar equator as each solar cycle progresses.

For further information see http://sites.google.com/site/climatediceandthebutterfly/

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Tauranga May rainfalls 1898 - 2013

Weather Eye
with John Maunder

Rainfalls for the month of May have been recorded in Tauranga since 1898 (except for 1904, 1907, 1908, and 1909).

The graph shows the range of rainfalls from an extreme high of 634mm in 2005 to a low of 13mm in 2001.


The second wettest May was 1950 when 311mm was recorded, and the second driest May was in 1918 when only 24mm fell. The long-term average rainfall for Tauranga for May is 124mm. The rainfall for May 2013 was 119.0 mm.

Apart from the exceptional rainfall of 634mm in May 2005, the graph shows a small decrease in the overall May rainfalls in the last 50 years (1961-2010) from an average of 115mm, compared with an average of 126mm in the 50 years from 1911-1960.

Since 1898, there have been 14 May months with a rainfall of 200mm or more, but only four May months with rainfalls of 30mm or less. 

Of particular significance is the exceptional rainfall in May 2005. I estimate that such a rainfall is likely to occur in Tauranga only about twice in every 1000 years, which among things suggests central government could well have had a much more important role in relationship to the financial implications of the floods, which affected Tauranga during that month.

 

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yTaueon Tauranga May Temeratures

Weather Eye
with John Maunder

Tauranga Afternoon Temperatures 1913-2013

 

 

Temperatures have been recorded in the Tauranga area at several sites over the last 100 years including the current Tauranga Airport site from June 1990.


It is very common for areas such as Tauranga to have had different observation sites over the years and the readings from the earlier sites have been adjusted to the present site using "standard climatological procedures".

It is considered that the temperature series described here is a fair and true record of what the temperature would have been if the current observation site (Tauranga Airport) had been used throughout the period.

It is important to note, that in considering “climate change”, the methodology used in computing an ‘official’ set of climate observations is very important as otherwise erroneous conclusions may be drawn.

Traditionally, temperature observations have been recorded with a set of maximum and minimum temperature thermometers. These record the daily maximum temperature (usually recorded in mid-afternoon), and daily minimum temperature (usually recorded just before dawn).

This analysis of temperatures for Tauranga are those for the average daily maximum temperatures. Later analyses will be for the average daily minimum temperatures.

The graph shows details of the average daily maximum temperatures (called simply "afternoon" from now on), for Tauranga for May from 1913-2012. Note that April 1947 is not included because of incomplete data.

The long-term average afternoon temperature in May for Tauranga is  16.9 degrees C, ranging from the "cool" May months of 1936, 1940, 1949 with an average afternoon temperature of 14.9 degrees C, to the  "warm" May months of 1916 (19.3 degrees C), 2010 (19.1 degrees C), and 2007 (18.9 degrees).

The graph of the average afternoon temperatures for May shows generally "normal" variations from May to May.

However, the last 20 May months were a little "warmer" than other May months since 1913.

From 1913 to 2012, there have been 10 May months with an average afternoon temperature of 18 degrees or more, and 11 May months with an average afternoon temperature of less than 16 degrees. The value for May 2013 was 18.5 degrees, the fifth warmest on record.

The 12 "warmest" May months (in terms of afternoon temperatures) on record, in chronological order, are 1916, 1928,1938, 1950,1999, 2000, 2003, 2005, 2007, 2010, and 2013.

In contrast, the 11 "coolest" May months (in terms of afternoon temperatures) on record, in chronological order, are 1913, 1920, 1924, 1936, 1940, 1945, 1959, 1967, 1977, 1983,  and 1992.

The average afternoon temperature in May during the period 1914-1962 was 16.7 degrees, compared with 17.1 degrees from 1993 to 17.1 degrees from 1993 to 2011.

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Tauranga June Rainfalls 1898-2013
 
 
Rainfalls for the month of June have been recorded in Tauranga since 1898 (except for 1904, 1907, 1908, and 1909).


The graph shows the range of rainfalls from an extreme high of 381 mm in 1925 to a low of 19 mm in 1906.

The second wettest June was 1920, when 309 mm was recorded, and the second and third driest June months were in 1959 and 2012 when only 27 mm fell.

The long-monthly average rainfall for Tauranga for June is 131 mm.

The graph of the June rainfall shows ‘normal’ variations from year to year. There is a small decrease in the overall June rainfalls during the last 50 years (1961-2010) from an average of 126 mm, compared with an average of 139 mm during the 50 years from 1911-1960. 

Since 1898, there have been 16 June months with a rainfall of 200 mm or more, but only five June months with rainfalls of 40 mm or less. The rainfall for June 2013 was 140 mm.
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June 2013 temperatures

The graph shows details of the average daily maximum temperatures (called simply "afternoon" from now on), for Tauranga for June from 1913-2012.

(Note that June 1964 is not included because of incomplete data)

Temperatures have been recorded in the Tauranga area at several sites over the last 100 years including the current Tauranga Airport site from June 1990.

The long-term average afternoon temperature in June for Tauranga is 14.7 degrees C, ranging from the "cool" June months of 1972 (13.0 degrees C), 1936 (13.2 degrees C), and 1933 (13.3 degrees C), to the  "warm" June months of 1916, and 2011 (16.6 degrees C), 2002 and 2003 (16.5 degrees C).

The graph of the average afternoon temperatures for June shows generally "normal" variations from June to June over the last 100 years, but many of the last 15 June months since 1996 have been a little "warmer" than other June months since 1913.

From 1913 to 2012, there have been 13 June months with an average afternoon temperature of 15.6 degrees C or more, and 12 June months with an average afternoon temperature of less than 13.9 degrees C. The value for June 2013 was 15.5degrees C.

The eighth "warmest" June months (in terms of afternoon temperatures) on record, in chronological order, are 1916, 1971,1981, 1998, 1999, 2002, 2003, 2011.

By contrast, the seventh "coolest" June months (in terms of afternoon temperatures) on record, in chronological order, are 1933,1936,1941,1944,1969,1972,1976.

The average afternoon temperature in June during the period 1914-1962 was 14.7 degrees, compared with 14.8 degrees from 1963 to 2011.

For further information log onto https://sites.google.com/site/climatediceandthebutterfly/ and for a complete list of my WeatherEyes see: https://sites.google.com/site/theweatherclimateeye/ ,and for my new web site on “Maunders Future Climate” see https://sites.google.com/site/maundersfutureclimate/

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Global Monthly Temperatures over in the last 15 years: No cooling or warming.

Weather Eye
with John Maunder

Global monthly temperatures in the last 15 years have been relatively steady with no real cooling or warming.


Global temperatures are compiled for various areas including global (land-ocean), global (meteorological stations), three latitude bands, and hemispheric, by the Goddard Institute for Space Studies of NASA.

A graph of the global temperatures since 1890 shows a general warming from 1910 to the early 1940s, a cooling from the early 1940s to the mid-1970s, and a general warming from the mid-1970s to about 1998. However, since then global monthly temperatures have been relatively steady with no real cooling or warming.

The yearly global temperatures (expressed as differences from the 1951-80 average) since 1998 are:  1998, +0.58 degrees; 1999, +0.33; 2000, +0.35; 2001, +0.48; 2002, +0.56; 2003, +0.56; 2004, +0.49; 2005, +0.62; 2006, +0.55; 2007 +0.58; 2008, +0.44, 2009, +0.57 ;  2010, +0.63 ; 2011, +0.51 degrees; and 2012, 

The graph shows the monthly mean global surface temperature anomaly from the base period 1951-1980. The black line shows meteorological stations only; the dotted line is the land-ocean temperature index obtained from satellite measurements.

 

 

http://www.sunlive.co.nz/blogs/printer-friendly/4996-july-tauranga-rainfalls.html

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Throwing the weather dice

Weather Eye
with John Maunder

Weather dice were shown on the cover of my book (shown below) published in 1968.

The cover, which has two dice on a "monopoly board" with various weather symbols on each side of the dice, represent the reality that most,  if not all, of the weather (and ultimately most of the climate), is ultimately related to how the weather dice fall.

Who or what controls the fall of the weather dice, and how significant the role of human induced activities is, is the ultimate question for all meteorologists and climate scientists.

However, if the "butterfly effect" (see below) is correct, we may really just have to continue to live, and adapt to whatever the weather and the climate provides.

* Professor Edward Lorenz (1917-2008) was a meteorologist who worked at the Massachusetts Institute of Technology (MIT) in the United States, who in 1972 presented an academic paper entitled "

Predictability: Does the flap of a butterfly's wings in Brazil set off a tornado in Texas?"

This paper resulted in the development of "chaos theory" or simply "the butterfly effect" which among other things, endeavours to explain why it is so hard to make good weather forecasts beyond about 10 days, and has implications for making good climate forecasts, particularly when considering the natural causes of climate change."  For further details see http://www.answers.com/topic/Edward-Norton-Lorenz.

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Climate Extremes in New Zealand

Weather Eye
with John Maunder

Since instrumental records became available in the 1850,s, climatic values show a range from the highest temperature of 42.4 degrees C recorded in Rangiora on February 7, 1973, to the lowest temperature of-25.6 degrees C in Eweburn,Ranfurly on 17 July 1903. In terms of rainfall extremes, values vary from the most intense rainfall in 10 minutes at recorded in Tauranga on 17 April 1948, to 16,617 mm in a calendar year at Cropp in the Hokitika catchment in 1998.

Each year, the National Institute of Water and Atmospheric Research updates the weather extremes recorded in New Zealand since observations were officially recorded in the 1850’s. The current extremes – up to December 2012 – include the following:

Wettest: 34 mm in 10 minutes in Tauranga on April 17 1948. 134 mm in one hour in the Hokitika Catchment. This site also has the records for the highest 24 hours fall of 758 mm on December  27/28, 1989, the highest 48 hour fall of 1049 mm on December 11/12/13, 1995, the highest fall in a calendar month of 2927 mm in December 1995, and the highest fall in a calendar year of 16,617 mm in 1998. 

Driest: Only 9 mm of rain fell at Cape Campbell (Marlborough) from January to March 2001, the driest three-months ever recorded in New Zealand. The driest six months was also at Cape Campbell from November 2000 to April 2001 when only 52 mm of rain was recorded. The driest 12 months was in Alexandra from November 1963 to October 1964, when only 167 mm was recorded. The longest period without rain is 71 days, which occurred in Wai-iti, Marlborough starting in February 8,1939.

Warmest: Until 1973, the highest temperatures officially recorded in New Zealand was 101.3 degrees Fahrenheit (38.4 degrees Celsius) at Ashburton and Darfield on January 19, 1956. However, under extreme north-westerly conditions on February 7, 1973, 42.4 degrees C (108.3 degrees Fahrenheit) was recorded at Rangiora. A temperature of 42.3 degrees C was also recorded on this day at Jordan, Marlborough.

Coldest: The coldest air temperature ever recorded was -25.6 degrees C in Eweburn, Ranfurly on July 17, 1903. The lowest grass temperature is -21.6 degrees C recorded at Lake Tekapo on August 4, 1938.

Sunniest: Nelson, Takaka, Riwaka, Blenheim, Lake Tekapo, Tauranga and Whakatane often appear in the list of very sunny places in New Zealand, but officially, Nelson has recorded the most sunshine in any one year with 2711 hours in 1931, with Blenheim recording 2673 hours in 1961. In contrast, only 1333 hours of sunshine was recorded in Invercargill in 1983. For one month, the sunniest location is Nelson with 336 hours in December 1934, and the least sunny location is Taumarunui with only 27 hours in June 2002. 

Wind Gust: The highest wind gusts recorded in New Zealand were 250 km/h at Mt John, Canterbury on April 17, 1970, and 248 km/h at Hawkins Hill, Wellington on November 6, 1959, and July 4, 1962.

For further information log onto https://sites.google.com/site/climatediceandthebutterfly/

 
 
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Tauranga August Rainfalls 1898-2013

Weather Eye
with John Maunder

Rainfalls for the month of August have been recorded in Tauranga since 1898 (except for 1904, 1907, 1908, and 1909).


The graph shows the range of rainfalls from an extreme high of 274 mm in 2010 to a low of only 17 mm in 1914.

The second wettest August was 1916 when 263 mm was recorded, and the second driest August was in 1982 when only 31 mm fell. The long-term average rainfall for Tauranga for August is 124 mm. The rainfall for Tauranga for August 2013 was 70 mm.

The graph of the August rainfall shows normal variations from year to year. There is a small decrease in the overall August rainfalls during the last 50 years (1961-2010)  from an average of 121 mm, compared with an average of 133 mm during the 50 years from 1911-1960.

Since 1898, there have been 15 August months with a  rainfall of 200 mm or more (14 of which occurred during the period 1900 to 1976, and only one August month since then (which was the highest rainfall in any August), but only two August months with a rainfalls of 40 mm or less.

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Tauranga August Afternoon Temperatures 1913-2013

Weather Eye
with John Maunder

Temperatures have been recorded in the Tauranga area at several sites in the last 100 years, including the current Tauranga Airport site from June 1990.

The graph shows details of the average daily maximum temperatures (called simply "afternoon") for Tauranga for August from 1913-2013.

The long-term average afternoon temperature in August for Tauranga is 14.8 degrees C, ranging from the "cool" August months of 1932 (13.8 degrees C), and 1941 and 1992 (both 13.9 degrees C), to the "warm" August months of 2013 (16.7 degrees C), and 16.4 degrees in 1915.

The graph of the average afternoon temperatures for August shows generally "normal" variations from August to August during the last 100 years, but five of the last August months have been a little "warmer" than other August months since 1913. This includes August 2013, which was 1.9 degrees C above average and the warmest on record.

From 1913 to 2013, there have been 11 August months with an average afternoon temperature of 15.8 degrees C or more, and 13 August months with an average afternoon temperature of less than 14.3 degrees C.

The sixth "warmest" August months (in terms of afternoon temperatures) on record, in chronological order, are 1915, 1967, 1971, 2009, 2012, and 2013.

By contrast, the fifth "coolest" August months (in terms of afternoon temperatures) on record, in chronological order, are 1932, 1941, 1966, 1992, and 2004.

The average afternoon temperatures during August for the period 1914-62 were14.7 degrees, compared with 15 degrees from 1963 to 2011.

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The first 33 WeatherEyes

Weather Eye
with John Maunder

The Sun pays no heed to human committees - this phrase with a minor change is given in a NASA release on "New Solar Cycle Prediction" on May 29, 2009.

Sunset from a cruise ship near Perth Photo: John Maunder

The Weekend Sun newspaper is published every Friday in Tauranga (New Zealand) and contains a range of local information including comments from several columnists.

During 2012, I provided a "Weather Eye" comment, which was generally published on the second and fourth Friday of each month. My column was also published on the website SunLive, which attracts over 200,000 weekly visitors.

From March 2013 my column is continuing and is now published exclusively on Sunlive.

A list of the first 32 WeatherEyes and the web site address in SunLive for each of them is available on the web site:

http://sites.google.com/site/theweatherclimateeye/

The first 32 WeatherEyes contain a wide range of topics on various aspects of the weather/climate scene including the following:

 

Tauranga Annual Rainfalls since 1898

Changing Spots on the Sun

New Zealand Climate Extremes: Tauranga has one of them

Climate Change and Villach - what is the connection?

Global Annual Temperatures: 1880-2012

Are we getting warmer or not?  Global monthly temperatures 1996-2013

England -Winters of the last 200 years 

Tauranga Annual Afternoon Temperatures 1913-2013  

Sunspots and the Maunder Butterfly  

Global monthly temperatures over the last 15 years: no warming or cooling

The weather dice and the butterfly 

Tauranga August Rainfalls 1898-2013

Tauranga August Afternoon Temperatures 1913-2013

 

Dr John Maunder is a retired climate scientist now living in Tauranga. He was President of the Commission for Climatology of the World Meteorological Organization (WMO) from 1989 to 1997. Over the last 60 years he has written four academic books and has been involved in the ‘weather busines’ in various countries, including New Zealand, Australia, Canada, USA, Ireland, Switzerland, and the UK.

For further information, Google ‘Dr John Maunder’ or email climate@ihug.co.nz

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Tauranga: September rainfalls 1898-2013

Weather Eye
with John Maunder

Rainfalls for the month of September have been recorded in Tauranga since 1898, except for 1904, 1907, 1908, and 1909.

The graph shows the range of rainfalls from an extreme high of 274 mm in 1973 to a low of only 16 mm in 1965. The second wettest September was 1900 when 256 mm was recorded, and the second driest September was in 1944 when only 27 mm fell. The long-term average rainfall for Tauranga for September from 1898-2013 is 105 mm.

The graph of the September rainfall shows normal variations from year to year. There is a very small decrease in the average of the September rainfalls during the last 50 years (1961-2010) from an average of 103 mm, compared with an average of 105 mm during the 50 years from 1911-1960.   Since 1898, there have been five September months with a  rainfall of 200 mm or more (four of which occurred during the period 1900 to 1928, but only one September 200 mm month since then), compared with six September months with a rainfalls of 40 mm or less.  The rainfall for September 2013 was 95 mm.

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Tauranga: September Afternoon Temperatures1914-2013

Temperatures have been recorded in the Tauranga area at several sites in the last 100 years, including the current Tauranga Airport site from June 1990.

The graph shows details of the average daily maximum temperatures (called simply "afternoon") for Tauranga for September from 1914-2013.

The long-term average afternoon temperature in September for Tauranga is 16.6 degrees C, ranging from the "cool" September months of 1964 (14.8 degrees C), and 1977 (14.9 degrees C), to the "warm" September months of 1915 (18.4 degrees C), and 18.3 degrees in 1914. The afternoon temperature for 2013 was 17.1 degrees.

The graph of the average afternoon temperatures for September shows generally "normal" variations from September to September during the last 100 years, but five of the warmest six September months occurred  from 1913 to 1921. From 1914 to 2013, there have been nine September months with an average afternoon temperature of 17.5 degrees C or more, and eight September months with an average afternoon temperature of less than 15.4 degrees C.

The eighth "warmest" September months (in terms of afternoon temperatures) on record, in chronological order, are 1914, 1915, 1916, 1921, 1926, 1940, 2006, and 2009. By contrast, the eighth "coolest" September months (in terms of afternoon temperatures) on record, in chronological order, are 1935, 1964, 1967, 1977, 1992, 1993, 1994,  and 1997.

The average afternoon temperature during September for the period 1914-62 was 16.6 degrees, compared with 16.5 degrees from 1963-2011.

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Is the Arctic Sea ice decreasing or increasing?

Weather Eye
with John Maunder

The University of Illinois compiles daily data of the extent of the Arctic sea ice. The data is available for any day from 1980 to the present; and allows a direct comparison between the extent of the Arctic sea ice on any two days during this period.

The area of Arctic ice for each month from 2002 to today can also be seen on a website, produced by the Japan Aerospace Exploration Agency. As shown in the graph below, during the last 10 years there has been decreases in the extent of Arctic sea ice in the Northern Hemisphere summer. However, the current NH summer season shows a reversal in this trend.

Date for the Arctic sea ice in the Northern Hemisphere summer shows that 2012 had lowest extent of the ice (in recent times), followed by 2007 (second), 2011 (third), and 2008 (fourth). However, for 2013 the Arctic ice sheet increased considerably and is now (October 2013) back to the levels of the first decade of 2000.

Time will tell whether this trend towards more ice in the Arctic will continue with its implications for among other things navigation.

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Temperatures in central England from 1650 to 2013

Weather Eye
with John Maunder

Various people have been credited with the invention of the thermometer and Galileo Galilei seems to be the first in the early 1600s; with Robert Fludd in 1638 being the first to show a scale to the new invention.

Thermometers, as we now know them, were then available to record air temperatures; and the first known temperatures were those recorded in England at about 1650.

The graph below shows the central England surface air temperature series, which is the longest existing meteorological record. Thin lines show the annual values; and the thick lines show the running 11-year average. The graphs for the annual, summer and winter temperatures have been prepared using the composite monthly meteorological series, originally painstakingly homogenised and published by the late professor Gordon Manley in 1974. The data series is now updated by the UK’s Hadley Centre, and has been updated this month (October 2013).

Among other things, the graphs show the cold of the 1660-1670 decade, associated with very low sunspot numbers; the 1815-1816, a “year without a summer”, associated with the Mount Tambora volcano in Indonesia; and the warming of the 1990-2000 decade.

The graph is one of many from the website: http://climate4you.com

It gives links to many official climate data websites, produced by NASA, NOAA, and The University of East Anglia, etc.

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Tauranga's October Rainfalls 1898-2013

Weather Eye
with John Maunder

 

The below graph shows the range of Tauranga’s October rainfalls, from an extreme high of 357 mm in 1916 to a low of only 7 mm in 1984. Rainfall in October 2013 was the third lowest on record.

 

 

The second wettest October was 1928, when 269 mm was recorded; and the second driest October was in 1938, when only 11 mm fell. The long-term average rainfall for Tauranga in the month of October is 110 mm.

The graph of the October rainfall shows at first glance normal variations from year to year. However, there has been a notable decrease in the October rainfalls during the last few years. Indeed, the average October rainfall in Tauranga for the 50-year period from 1961-2010 of 88 mm is only 70 per cent of the rainfall for the 50-year period 1910-1960.

Overall, the yearly rainfalls in Tauranga have declined during these two 50-year periods from an average of 1365 mm to 1263 mm. However, the months of March and December each show increases in the rainfall for these same 50-year periods.

Since 1898, there have been 11 October months with a rainfall of 200 mm or more (10 of which occurred during the period 1900-1958), and only one October month since then has recorded this much. Plus, 10 October months have experienced rainfalls of 25 mm or less.

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October Afternoon temperatures 1914-2013

Weather Eye
with John Maunder

This year, Tauranga had its warmest October since records began in 1913.

Temperatures have been recorded in the Tauranga area at several sites in the last 100 years, including the current Tauranga Airport site from June 1990.

The graph shows details of the average daily maximum temperatures (called simply ‘afternoon’) for Tauranga for October from 1913-2013.

The long-term average afternoon temperature in October for Tauranga is 18.1 degrees Celsius, ranging from the cool October months of 1964 (15.7 degrees Celsius), and 1992 (16.5 degrees Celsius), to the warm October months of 2013 (20.3 degrees Celsius), and 1915 (19.9 degrees Celsius).

The graph of the average afternoon temperatures for October shows generally normal variations from October to October during the last 100 years. But of note, are the three warm Octobers in the consecutive years 1913, 1914 and 1915.

The average October afternoon temperatures during the 50 years from 1963-2011 of 18 degrees Celsius is slightly cooler than the 18.3 degrees Celsius recorded in the 50 years from 1914-1961.

From 1913 to 2013, there have been 12 October months with an average afternoon temperature of degrees Celsius or more; and eight October months have had an average afternoon temperature of 17 degrees Celsius or less.

The four warmest October months (in terms of afternoon temperatures), on record, in chronological order, are 1913, 1915, 1940, and 2013.

By contrast, the fifth coolest October months (in terms of afternoon temperatures), on record, in chronological order, are 1941, 1964, 1978, 1982, and 1992.

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Global Surface Temperatures Stable since 2000

Weather Eye
with John Maunder

Much has been written about what is happening to the global climate.

The following diagram shows the trends in global surface temperatures during the 160 years from 1850.

The graph shows a cooling from 1880 to 1895, a warming from 1915 to 1945, a cooling from 1945 to 1950, a warming from 1965 to 2000 – and stable temperatures since 2000.

Global monthly average surface air temperature since 1850 – according to Hadley CRUT, a cooperative effort between the Hadley Centre for Climate Prediction and Research and the University of East Anglia's Climatic Research Unit (CRU) in the UK – sees the blue line represent the monthly values.

An introduction to the dataset has been published by Brohan et al. (2005). The base period is: 1961-1990. And, the last month shown is: December 2010. The diagram was last updated January 3, 2011.

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Global Average Temperatures Observed from Satellites 1979-2013

Weather Eye
with John Maunder

Global average temperatures of the troposphere – those observed from NOAA satellites – are computed each month by the University of Alabama. Temperatures shown are deviations from the average for the 30-year period 1981 to 2010.

The chart shows that, since 1979, when reliable satellite observations have been available, there has been little significant changes in global temperatures in the troposphere (except for ‘normal’ variations), apart from a small warming trend.

The coolest months (since 1979), were September 1984 (-0.49 degrees) and November 1984 (-0.42 degrees), associated with the cooling from the Mount Pinatubo volcanic eruption.

The warmest months were February and April 1998 (both +0.76 degrees), associated with a very strong El Nino event.

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Tauranga’s November rainfalls from 1898-2013

Weather Eye
with John Maunder

The graph shows the range of November rainfalls from 1898 to 2013 in Tauranga, from an extreme high of 285 mm in 1916 to a low of only 12 mm in 2009.

The second wettest November was 1967, when 240 mm was recorded; the second driest November was in 2011, when only 13 mm fell. The long-term average rainfall for Tauranga in the month of November is 85 mm. The rainfall for November 2013 of 66 mm is only 80 per cent of the average, but it’s still the wettest November since 2005 and the fifth wettest since 1995.

The graph of the November rainfall shows at first glance normal variations from year to year. However, there has been a notable decrease in the November rainfalls during the last few years. Indeed, the average November rainfall in Tauranga for the 50-year period from 1961-2010 of 78 mm is only 85 per cent of the rainfall for the 50-year period 1910-1960.

Since 1898, there have been 11 November months with a rainfall of 150 mm or more (seven of which occurred during the period 1913-1952). In chronological order, the wettest Novembers are: 1913 with 205 mm, 1916 with 285 mm, 1925 with 167 mm, 1933 with 152 mm, 1936 with 153 mm, 1938 with 174 mm, 1952 with 232 mm, 1967 with 240 mm, 1981 with 191 mm, 1995 with 204 mm, and 1999 with 160 mm.

In terms of dry Novembers, there have been 13 months with rainfall of 30 mm of less, four of which have occurred since 1997. In chronological order the driest Novembers are 1901 14 mm, 1902 26 mm, 1914 with 17 mm, 1919 with 23 mm, 1928 with 28 mm, 1945 with 20 mm, 1963 with 30 mm, 1982 with 24 mm, 1984 with 19 mm, 1997 with 24 mm, 2009 with 12 mm, 2011 with 13 mm, and 2012 with 27 mm.

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November 2013 warmest on record

Weather Eye
with John Maunder

During November 2013 Tauranga had its warmest November since records began in 1913.

Temperatures have been recorded in the Tauranga area at several sites in the last 100 years, including the current Tauranga Airport site from June 1990.

The graph shows details of the average daily maximum temperatures (called simply ‘afternoon’) for Tauranga for Novembers from 1913-2013.

The long-term average afternoon temperature in November for Tauranga is 20.1 degrees Celsius, ranging from the cool November months of 1976 (18.4 degrees Celsius), and 1941 (18.5 degrees Celsius), to the warm November months of 2013 (22.3 degrees Celsius), and 1954 (22 degrees Celsius).

The graph of the average afternoon temperatures for November shows generally normal variations from November to November during the last 100 years, but of note are the three warm Novembers in the years 2009, 2010, 2011, and 2013.

The average November afternoon temperature during the 50 years from 1963 to 2011 of 20.1 degrees Celsius, is nearly the same as the 20 degrees Celsius recorded in the 50 years 1914 to 1961.

From 1913 to 2013, there have been 15 November months with an average afternoon temperature of 21 degrees Celsius or more, and seven November months with an average afternoon temperature of less than 19.0 degrees Celsius.

The seventh warmest November months (in terms of afternoon temperatures), on record, in chronological order, are 1945, 1954, 1961, 1982, 2010, 2011, and 2013.

By contrast, the seventh coolest November months (in terms of afternoon temperatures), on record, in chronological order, are 1918, 1930, 1946, 1968, 1976, 1991, and 1985.

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I

IINN n the bleak mid-winter


Weather Eye
with John Maunder

In the bleak mid-winter,

Frosty wind made moan,

Earth stood hard as iron,

Water like a stone,

Snow had fallen,

Snow on snow,

Snow on snow,

In the bleak mid-winter,

Long ago.

These words, from the first verse of the well-known carol, were written by the English poet Christina Rossetti in 1872 in response to a request from the magazine ‘Scribner’s Monthly’ for a Christmas poem.

It was published posthumously in Rossetti’s ‘Poetic Works’ in 1904. The poem became a Christmas carol after it appeared in ‘The English Hymnal’ in 1906. The text of this Christmas poem has been set to music many times; the most famous settings being composed by Gustav Holst and Harold Edwin Darke in the early 20th Century.

The version by Darke is favoured by cathedral choirs, and is the one usually heard performed on the radio broadcasts of ‘Nine Lessons and Carols’ by the King’s College choir.

Of some significance is that on December 15, the ‘Mail Online’ (UK) had the following headlines relating to a severe snow storm, which hit the Holy City on Saturday – and at the same time Cairo experienced its first snowfall in more than 100 years. Perhaps the Christmas carol has come alive?

A Christmas card come to Life: Jerusalem hit by worst snowstorm for 20 years, as eight inches fall across Holy City.

  • Unusually heavy snowfall, as temperatures dip below freezing.
  • Dome of the Rock and Western Wall bathed in white blanket.
  • Prime Minister Natanyahu gets in on the fun with family snowball fight.

The weather is always with us; and although we may all hope the weather this Christmas will be to our liking, it is perhaps important to remember that in the Southern Hemisphere where the carol ‘In the Bleak Mid-Winter’ may seem unusual, there have been two significant and tragic weather events.

The first was on Christmas Eve in New Zealand, in 1953, when the Tangiwai rail disaster occurred with loss of 151 lives. The second was in Darwin, on Christmas Day 1974, when Tropical Cyclone Tracy killed 71 people and destroyed 80 per cent of the city’s houses.

I take this opportunity of wishing all my readers a very happy Christmas and I will be back in 2014 with some more Weathereyes.

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Tauranga’s December rainfalls 1898-2013

Weather Eye
with John Maunder

The graph below shows the range of Tauranga’s December rainfalls, from an extreme high of 447mm in 1962 to a low of only 4mm in 1930.

The second wettest December was 2011, when 276mm was recorded; and the second driest December was in 1994, when only 14mm fell.

The long-term average rainfall for Tauranga for December is 100mm.

The graph of the December rainfall shows, at first glance, normal variations from year to year.

However, there has been a notable increase in the December rainfalls during the last few decades. Indeed, the average December rainfall in Tauranga for the 50-year period from 1961-2010 of 109mm is 20 per cent higher than the rainfall for the 50-year period 1911-1960.

Since 1898, there have been eight Decembers with a rainfall of 200mm or more, five of which occurred during the period 1962 to 2011. Seven December months have experienced rainfalls of 30mm or less. Of significance are the rainfalls in the consecutive December months of 1922 and 1993, of 447mm and 224mm respectively.

In chronological order the eighth wettest Decembers are 1924 with 225 mm, 1928 with 227mm, 1936 with 240mm, 1962 with 447mm, 1963 with 224mm, 1996 with 241mm, 2001 with 208mm, and 2011 with 276mm.

In contrast, the seventh driest December months in chronological order are 1902 with 27mm, 1912 with 22mm, 1919 with 22mm, 1930 with 4mm, 1986 with 30mm, 1990 with 21mm, and 1994 with 14mm.

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Tauranga Annual Rainfalls 1898-2013

Weather Eye
with John Maunder

 Monthly rainfalls for Tauranga have been recorded at several recording sites during the last 114 years.

From January 1898 to December 1904, the observation site was described as the Tauranga Harbour, from November 1904 to April 1907 the site was described as simply ‘Tauranga’. From January 1910 to December 1923 the site was Waikareao, in Otumoetai; from January 1924 to September 1940 the site was at 148 Waihi Rd, in Judea; from October 1940 to January 1941 the site was at Te Puna; and from February 1941 to now, the site is Tauranga Airport.

The methodology use in adjusting the older sites to the current observing site is published in the ‘NZ Meteorological Service Miscellaneous Publication’ No 180 in 1984.

It is considered that the homogeneous rainfall series described here is a fair and true record of what the rainfall would have been if the current observation site (Tauranga Airport) had been used since 1898, with the understanding that although standard accepted methodologies have been used, any adjustments are only estimates of what would have occurred if the location of the rainfall records had always been in the same place with the same surroundings and the same or similar recording gauge.

In terms of climate change (such as is it getting wetter or drier, or warmer or colder), the methodology used in computing an ‘official’ set of climate observations is very important, as otherwise erroneous conclusions may be drawn.

The long-term average rainfall for Tauranga for the calendar year is 1300mm, ranging from a low of 747mm in 2002, to a high of 2049mm in 1962.

For comparison, the rainfall for the last year, 2013, was 1073mm, which made it the 20 driest year since observations began in 1898.

Since 1898, there have been only four years with a rainfall of less than 900mm, they are 1914, 1982, 1993, and 2002.

And there’s only been four years with a rainfall of more than 1800mm; they are the two consecutive years of 1916 and 1917, plus 1938 and 1962.

The wettest years on record are: 1962 which had 2049mm or 57 per cent above of the long-term average, while 1917 had 1985mm or 52 per cent above average. Also, 1916 had 1941mm or 49 per cent above average, plus 1938 (1817mm), 1920 (1789mm), 1956 (1777mm), 1979 (1730mm), 2011 (1696mm), 2005 (1682mm), and 1935 (1670mm).

In chronological order, these wettest years occurred in 1916, 1917, 1920, 1935, 1938, 1956, 1962, 1979, 2005 and 2011.

In contrast, the 10 driest years on record are: 2002 (747mm or 48 per cent below the long-term average), 1914 (773mm or 41 per cent below the long-term average), 1982 (842mm or 36 per cent below the long-term average), plus 1993 (863mm), 1906 (950mm), 1919 (962mm), 1997 (978mm), 1973 (989mm), 1986 (991mm), and 1999 (1002mm).

In chronological order, these driest years occurred in 1906, 1914, 1919, 1973, 1982, 1986, 1993, 1997, 1999, and 2002.

********************************

Tauranga’s December afternoon temperatures 1913-2013


Weather Eye
with John Maunder

Temperatures have been recorded in the Tauranga area at several sites during the last 100 years, including at the current Tauranga Airport site from June 1990.

The graph shows details of the average daily maximum temperatures, called simply ‘afternoon’, for Tauranga for December from 1913-2013.

The long-term average afternoon temperature in December for Tauranga is 22.1 degrees Celsius, ranging from the ‘cool’ December months of 2004 (20.1 degrees Celsius), 1968  (20.5 degrees Celsius) and 1944 and 1951 (both 20.7 degrees Celsius), to the ‘warm’ December months of 1940 (24.4 degrees Celsius), 1937 (24.0 degrees Celsius), and 1990 (23.8 degrees Celsius).

The graph of the average afternoon temperatures for December shows generally normal variations from December to December during the last 100 years.

The average December afternoon temperature during the 50 years from 1963 to 2011 of 22.2 degrees Celsius, is exactly the same figure recorded in the 50 years from 1914 to 1961.

The average afternoon temperature in December 2013 was 22.8 degrees Celsius.

From 1913 to 2013, there have been 23 December months with an average afternoon temperature of 23 degrees Celsius or more, and 12 December months with an average afternoon temperature of less than 21 degrees Celsius or less.

The seven warmest December months (in terms of afternoon temperatures), on record, in chronological order, are 1930, 1934, 1937, 1940, 1990, 1993, and 1994.

By contrast, the seven coolest December months (in terms of afternoon temperatures), on record, in chronological order, are 1921, 1946, 1951, 1962, 1968, 1977, and 2004.

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Tauranga’s Warmest Year is 2013

 
Weather Eye
with John Maunder

During 2013, Tauranga had it warmest year ( in terms of average afternoon temperatures) since records began in 1914.

Temperatures have been recorded in the Tauranga area at several sites in the last 100 years, including the current Tauranga Airport site from June 1990.

The graph shows details of the average daily maximum temperatures (called simply ‘afternoon’), for Tauranga for the years 1914-2013.

The long-term average afternoon temperatures for Tauranga for a calendar year is 18.6 degrees Celsius, ranging from the cool years of 18.1 degrees Celsius in 1976, 18.1 degrees Celsius in 1992, 18.2 degrees Celsius in 1923, and 18.3 degrees Celsius in 1918

Tauranga’s warm years are: 20.2 degrees Celsius in 2013, 20.1 degrees Celsius in 1916, 20 degrees Celsius in 1998, and 19.9 degrees Celsius in 2010.

As noted above, 2013 was the warmest year on record, with an average afternoon temperature of 20.2 degrees Celsius.

Since 1914, there have been only 10 calendar years with an average afternoon temperature of 19.6 degrees Celsius or more. In chronological order these years are: 1914, 1915, 1916, 1928, 1998, 1999, 2005, 2010, 2012, and 2013.  

In comparison, there have been 11 calendar years with an average afternoon temperature of 18.5 degrees Celsius or less. In chronological order these years are: 1918, 1920, 1923, 1941, 1945, 1965, 1976, 1977, 1980, 1991, and 1992.

The graph of the average afternoon temperatures for the years 1914-2013 shows generally normal variations from year to year from 1915 to the mid-1990s, followed by several years of above-average temperatures.

The average afternoon temperature shows a warming of about 0.8 degrees Celsius during the 50 years from 1963-2013 (of 19 degrees Celsius), compared with 18.2 degrees Celsius during the 50 years from 1914-1962.

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Tauranga’s January Rainfalls 1898-2014

 
Weather Eye
with John Maunder

The graph shows the range of Tauranga’s January rainfalls from 1898-2014, varied from an extreme high of 532 mm in 1907 to a low of only 1 mm in 1928. But do note the records for January 1904, 1908, and 1909 are incomplete.

The second wettest January was 2011, when 347 mm was recorded; and the second driest January was in 2013, when only 4 mm fell.

The long-term average rainfall for Tauranga for January is 89 mm. The rainfall for January 2)14 was 50 mm.

The graph of the January rainfall shows generally normal variations from year to year.

Since 1898 there have been eight January months with a rainfall of 180 mm or more, with two such wet January months, 1940 and 1941, being consecutive.

Thirteen January months have experienced rainfalls of less than 20 mm, with two such dry January months, 1978 and 1979, being consecutive.

In chronological order, the eighth wettest January months are 1907 with 532 mm, 1920 with 196 mm, 1940 with 254 mm, 1941 with 245 mm, 1951 with 204 mm, 1965 with 183 mm, 1989 with 268 mm, and 2011 with 347 mm.

In contrast, the sixth driest January months in chronological order are 1900 with 8 mm, 1928 with 1 mm, 1944 with 10 mm, 1957 with 8 mm, 1988 with 9 mm, and 2013 with 4 mm.


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GROUNDHOG DAY   February 2

 
Weather Eye
with John Maunder

Groundhog Day, February 2nd, is a popular tradition in the United States. It is also a legend that traverses many centuries, its origins clouded in the mists of time with ethnic cultures and animals awakening on specific dates.

Myths such as this tie our present to the distant past, when nature did indeed influence our lives –and to many, nature is still influencing out lives. It is also the day the Groundhog comes out of his hole after a long winter sleep to look for his shadow.

Tradition has it if the groundhog sees his shadow, he regards it as an omen of six more weeks of bad weather and returns to his hole. But, if the day is cloudy and, hence, shadow less, he takes it as a sign of spring and stays above ground.

The groundhog tradition stems from similar beliefs associated with Candlemas Day and the days of early Christians in Europe. It marked a milestone in the winter and the weather that day was important. And according to an old English Song:

“If Candlemas be fair and bright,

Come, winter, have another flight;

If Candlemas brings clouds and rain,

Go winter, and come not again.”

The Roman legions, supposedly brought this tradition to the Teutons, or Germans, who picked it up and concluded that if the sun made an appearance on Candlemas Day, an animal, the hedgehog, would cast a shadow; thus predicting six more weeks of bad weather, which they interpolated as the length of the ‘Second Winter’.

In the United States, Pennsylvania’s earliest settlers were Germans and they found groundhogs in profusion in many parts of the State. They determined the groundhog, resembling the European hedgehog, was a most intelligent and sensible animal; and therefore decided if the sun did appear on February 2nd, this wise animal would see its shadow and hurry back into its underground home for another six weeks of winter.

The Germans thus recited:

“For as the sun shines on Candlemas Day,

So far will the snow swirl until the May”.

This passage may be the one most closely-represented by the first Punxsutawney Groundhog Day observances because there were references to the length of shadows in early Groundhog Day predictions. The ancient Candlemas legend and similar belief continue to be recognised annually on February 2nd, due to the efforts of the Punxsutawney Groundhog Club.

Early observances of Phil’s (the Groundhog) predictions were conducted privately in the wooded areas around the town. The celebration today sees thousands of visitors from worldwide as revellers await Phil’s appearance.

The ‘Punxsutawney Spirit’ newspaper is credited with printing the news of the first observance in 1886.

“Today is groundhog day, and up to the time of going to press the beast has not seen his shadow.”

In 1993, Columbia Pictures released the movie Groundhog Day starring Bill Murray. In the years following the release of the movie, record crowds numbering as high as 30,000 have visited Gobbler’s Knob in Punxsutawney.

Punxsutawney Phil gets his longevity from drinking “groundhog punch”. One sip, which is administered every summer at the Groundhog Picnic, gives him seven more years of life.

And, contrary to the media, Phil’s forecasts are not made in advance by the Inner Circle. After Phil emerges from his burrow on February 2nd, he “speaks” to the Groundhog Club President in Groundhogs. His proclamation is then translated for the world.

This year, the handlers for groundhog Punxsutawney Phil said he’s forecasting six more weeks of what already has felt like a brutally long and cold winter.

The US National Weather Service notes that the Punxsutawney Groundhog Day predictions have been right 10 times and wrong 15 times since 1988.

“The groundhog has shown no talent for predicting the arrival of spring, especially in recent years,” according to the Weather Service. “Phil’s competitor groundhogs across the Nation fared no better.”

However, I am sure that you, and many others, may well choose to believe the prediction of the famous Groundhog.


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Tauranga’s January Average Daily Afternoon Temperatures 1914-2014

  
Weather Eye
with John Maunder


Temperatures have been recorded in the Tauranga area at several sites during the last 100 years, including the current Tauranga Airport site from June 1990.

The graph shows details of the average daily maximum temperatures (called simply ‘afternoon’) for Tauranga for January from 1914-2014.

The long-term average afternoon temperature in January for Tauranga is 23.8 degrees Celsius, ranging from the cool January months of 1920, with 21.6 degrees Celsius , and 1939 posting 21.8 degrees Celsius, to the warm January months of 1935, achieving 27.7 degrees Celsius, while in 1970 the temperature reached 25.7 degrees Celsius.

The graph of the average afternoon temperatures for January shows generally normal variations from January to January during the last 100 years.

The average January afternoon temperature during the 50 years from 1963 to 2011 of 23.8 degrees Celsius is exactly the same average recorded in the 50 years 1914 to 1962.

From 1914 to 2014, there have been six January months with an average afternoon temperature of 25.5 degrees Celsius or higher, and seven January months with an average afternoon temperature of 22.5 degrees Celsius or lower.

The warmest six January months (in terms of afternoon temperatures), on record, in chronological order, are 1915, 1935, 1970, 1957, 1999, and 2009.

By contrast, the coolest seven January months (in terms of afternoon temperatures), on record, in chronological order, are 1918, 1920, 1922, 1925, 1930, 1939, and 1980.

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Global temperatures 1880-2013 – are we really getting warmer?


Weather Eye
with John Maunder

Global temperatures are compiled for various areas, including global (land-ocean), global (meteorological stations), three latitude bands, and hemispheric, by the Goddard Institute for Space Studies of NASA.

A graph of the global temperatures (for the land/ocean) from 1880 to 2013, show a general warming from 1910 to the early 1940s, a cooling from the early 1940s to the mid-1970s; and a general warming from the mid-1970s to about 1998.

However, since then, global annual temperatures have been relatively steady with no real cooling or warming.

The yearly global temperatures (expressed as differences from the 1951-1980 average), since 1998 are:

1998:   +0.58 degrees Celsius

1999:   +0.33 degrees Celsius

2000:   +0.35 degrees Celsius

2001:   +0.48 degrees Celsius

2002:   +0.56 degrees Celsius

2003:   +0.56 degrees Celsius

2004:   +0.49 degrees Celsius

2005:   +0.62 degrees Celsius

2006:   +0.55 degrees Celsius

2007:   +0.58 degrees Celsius

2008:   +0.49 degrees Celsius

2009:   +0.59 degrees Celsius

2010:   +0.66 degrees Celsius

2011:   +0.55 degrees Celsius

2012:   +0.57 degrees Celsius

2013:   +0.60 degrees Celsius

 

The green bars show the uncertainty estimates at various times

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Tauranga’s February rainfalls 1898-2014


Weather Eye
with John Maunder

Rainfalls for the month of February have been recorded in Tauranga since 1898 (except for 1904, 1908, and 1909).

The graph of February rainfalls in Tauranga shows the range of rainfalls from a high of 343mm in 1936 to a low of only 7mm in 1973 and 2011.

The graph shows predominantly "normal" variations from year to year.

However, the average rainfall for Tauranga for February during the 50 years 1961-2010 was 10mm less than the average rainfall during the previous 50 years 1911-1960.

 

 

Nine February months have had a rainfall of less than 15mm. Nine February months also have had a rainfall of 200mm or more.

The wettest February was 1936 with 343mm, and the second wettest February was 2001 when 268mm was recorded.

The driest February month was 1973 with 7mm, and the February months of 1942, 1987, and 2011 each had a rainfall of 8mm.

The rainfall for February 2014 was 64mm. The long-term February rainfall for Tauranga is 90mm.

In chronological order, the wettest nine February months were 1920, 1933, 1934, 1936, 1938, 1960, 1966, 2001, and 2004.

In chronological order, the driest nine February months were 1942, 1970, 1972, 1973, 1987, 1999, 2000, 2010, and 2011.

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Tauranga’s February afternoon temperatures 1915-2014

 
Weather Eye
with John Maunder

Temperatures have been recorded in the Tauranga area at several sites during the last 100 years, including the current Tauranga Airport site from June 1990.

It is very common for areas such as Tauranga to have had different observation sites during the years; and the readings from the earlier sites have been adjusted to the present site using ‘standard climatologically procedures'.

It is considered the temperature series described here is a fair and true record of what the temperature would have been if the current observation site (Tauranga Airport) had been used throughout the period.

It is important to note, that in considering ‘climate change', the methodology used in computing an ‘official' set of climate observations is very important – as otherwise erroneous conclusions may be drawn.

Traditionally, temperature observations have been recorded with a set of maximum and minimum temperature thermometers.

These record the daily maximum temperature (usually recorded in mid-afternoon), and daily minimum temperature (usually recorded just before dawn).

This analysis of temperatures for Tauranga is for the average daily maximum temperatures.

The graph shows details of the average daily maximum temperatures (called simply ‘afternoon'), for Tauranga for February from 1915-2014.

The long-term average afternoon temperature in February for Tauranga is 23.8 degrees Celsius, ranging from the ‘cool' February months of 1934, with an average afternoon temperature of 21.6 degrees C , and 1921 with an average afternoon temperature of 21.8 degrees Celsius, to the ‘warm' February months of 1916 (26.4 degrees Celsius), and 1998 (26.2 degrees Celsius).

The graph of the average afternoon temperatures for February shows generally ‘normal' variations from February to February.

The average afternoon temperature for the 49 years from 1963-2011 of 24.0 degrees Celsius is just 0.3 degrees Celsius higher than the average afternoon temperature for the 49 years from 1914-1962.

From 1915 to 2014, there have been six February months with an average afternoon temperature of 25.5 degrees Celsius or more, and six February months with an average afternoon temperature of 22.5 degrees Celsius or less.

The average afternoon temperature for February this year was 24.3 degrees Celsius, which was 0.5 degrees Celsius above the long term average.

The six ‘warmest' February months (in terms of afternoon temperatures) on record, in chronological order, are: 1916, 1928, 1954, 1955, 1998, and 2011.

In contrast the six ‘coolest' February months (in terms of afternoon temperatures) on record, in chronological order, are: 1921, 1931, 1934, 1940, 1976, and 2004.

 .

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Tropospheric  Average Temperatures 1979-2014


The latest global average temperatures of the troposphere – those observed from NOAA satellites – are computed by the University of Alabama at Huntsville, in the United States.

The chart shows since 1979, when reliable satellite observations have been available, there has been little overall trend (from the average temperatures during the 30-year period 1981 – 2010 in the temperatures in troposphere), apart from ‘normally expected' variations, except for a small warming trend.

The data for 2011 are as follows: January 0.0 degrees Celsius, February -0.02, March -0.10, April +0.12, May +0.14, June +0.32, July +0.38, August +0.33, September +0.29, October +0.12, November +0.12, December +0.10 degrees.

The data for 2012 are: January -0.09 degrees, February -0.12, March +0.11, April +0.29, May +0.29, June +0.37, July +0.28, August +0.34 , November +0.28, December +0.20 degrees.

The data for 2013 are: January +0.50 degrees, February +0.18, March +0.20, April +0.10, May +0.07, June +0.30, July +0.17, August +0,16, September +0.37, October +0.29, November +0.19, December +0.23 degrees.

The data for 2014 are: January +0.29 degrees Celsius, February +0.17 degrees Celsius.

The coolest months (since 1979) were September 1984 (-0.49 degrees Celsius) and November 1984 (-0.42 degrees Celsius), and the warmest months were February and April 1998 (both +0.76 degrees Celsius). The chart shows the ‘El Nino' warming in the 1998 period and the Mount Pinatubo (volcanic) cooling during the 1992-1993 period.


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Sunspots

 
Weather Eye
with John Maunder

The connection between solar activity and the earth's climate is an area of on-going and sometimes controversial research.

A sunspot is a relatively dark, sharply defined region on the solar disc - marked by an umbra (dark area) which is 2000 degrees C cooler than the effective photosphere temperature. The average diameter of a sunspot is 4000 km, but can exceed 200,000 km.

The NASA Solar Physics website ( and other web sites such as the Royal Observatory of Belgium) includes information on sunspot numbers, the ‘Maunder Minimum', and sunspot cycle predictions. The  sunspot index is updated monthly and available from 1749. The last time the monthly sunspot number was above 100 for any significant period of time was September 2002 when the value was 109.6, and the last time the value was above 200 was in August 1990 when the value was 200.3.

Mike Lockwood, Professor of Space Environmental Physics at Reading University, UK, thinks that the current period of solar activity is likely  become the first "grand solar minimum" for four centuries. During a grand minimum the normal 11-year solar cycle is suppressed and the sun has virtually no sunspots for several decades.

Lockwood thinks there is now a 25 per cent chance of a repetition of the last grand minimum, the late 17th century “Maunder Minimum”, when there were no sunspots for 70 years.

But Lockwood says we should not expect a new grand minimum to bring on a new little ice age. There may, however, still be noticeable consequences. For instance, long term cold winters in the UK are common when solar activity is low. And less solar activity can slow the jet stream, triggering a suite of interlinked extreme weather events.

There have been 24 grand solar minima in the past 10,000 years. Their history is reconstructed by looking for isotopes like carbon-14 that cosmic rays generate in the atmosphere.

The recent decline in solar activity may have helped cause the current “hiatus” in the pace of “global warming”.


The chart ( from the Royal Observatory of Belgium) above shows the monthly (and 13 –month smoothed number) values of the sunspot number since 1955.

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Tauranga’s March rainfalls from 1898-2014


Weather Eye
with John Maunder

Rainfalls for the month of March have been recorded in Tauranga since 1898 – except for 1904, 1908 and 1909.

This graph below shows the range of rainfalls from a high of 504mm in 1979, to a low of five mm in 1943.

The second wettest March was in 1972, when 318mm was recorded, and two March months – 1921 and 2010 – recorded 14mm.

The long-term average rainfall for Tauranga for March is 109mm. The rainfall for March 2014 was 43mm.

The graph shows no significant overall trend in rainfalls in March during the last 110 years, apart from a small increase in the average rainfall for the 50 years ending in 1960 of 103mm, to 117mm in the 50 years to 2010.

Since 1898, there have been eleven March months with a rainfall of 200mm or more, and eleven March months with a rainfall of 30mm or less.

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Climate extremes in NZ – Tauranga has one


Weather Eye
with John Maunder

Climate extremes in New Zealand, since instrumental records became available in the 1850s, show a range from the highest temperature of 42.4 degrees Celsius recorded in Rangiora on February 7, 1973, to the most intense rainfall in 10 minutes – which occurred in Tauranga on April 17, 1948.

Each year, the National Institute of Water and Atmospheric Research updates the weather extremes recorded in New Zealand since observations were officially recorded in the 1850s. The current extremes include the following:

Wettest: A recorded 34mm in 10 minutes in Tauranga on April 17, 1948.

About 134 mm happened in one hour at Cropp at Waterfall in the Hokitika Catchment. This site also has the records for the highest 24 hours' fall of 758mm on December 27-28, 1989, and the highest 48-hour-fall of 1049mm on December 11-13, 1995. It also had the highest fall in a calendar month of 2827mm in December 1995, and the highest fall in a calendar year of 16,617mm in 1998. 

Driest: Only nine mm of rain fell at Cape Campbell, Marlborough, from January to March 2001; the driest three months ever recorded in New Zealand.

The driest six months was also recorded at Cape Campbell, from November 2000 to April 2001 when only 52mm of rain was recorded. The driest 12 months was in Alexandra from November 1963 to October 1964, when only 167mm was recorded. The longest period without rain is 71 days, which occurred in Wai-iti, Marlborough, from February 8, 1939. 

Warmest: Until 1973, the highest temperatures officially recorded in New Zealand was 101.3 degrees Fahrenheit (38.4 degrees Celsius) at Ashburton and Darfield on January 19, 1956.

However, under extreme northwesterly conditions on February 7, 1973, there was a recorded 42.4 degrees Celsius (108.3 degrees Fahrenheit) at Rangiora.

A temperature of 42.3 degree Celsius was also recorded on this day at Jordan, Marlborough.

Coldest: The coldest air temperature ever recorded was minus 25.6 degrees Celsius in Eweburn, Ranfurly, on July 17, 1903. The lowest grass temperature is minus 21.6 degrees Celsius recorded at Lake Tekapo on August 4, 1938.

Sunniest: Nelson, Takaka, Riwaka, Blenheim, Lake Tekapo, Tauranga and Whakatane often appear in the list of very sunny places in New Zealand – but officially Nelson has recorded the most sunshine in any one year with 2711 hours in 1931, with Blenheim recording 2673 hours in 1961.

In the North Island, Whakatane recorded 2602 hours of sunshine in 2012. In contrast, only 1333 hours of sunshine was recorded in Invercargill in 1983.

For one month, the sunniest location is Nelson with 336 hours in December 1934 (with Taupo recording 225 hours in December in 1950); and the least sunny location is Taumaranui, with only 27 hours in June 2002. 

Wind Gust: The highest wind gusts recorded in New Zealand were 250km/h at Mt John, Canterbury, on April 17, 1970 and 248 km/h at Hawkins Hill, Wellington, on November 6, 1959, and July 4, 1962.

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March Average Afternoon Temperatures 1915-2014

Weather Eye
with John Maunder

Temperatures have been recorded in the Tauranga area at several sites during the last 100 years including the current Tauranga Airport site from June 1990.

The graph shows details of the average daily maximum temperatures, called simply ‘afternoon', for Tauranga for the months of March from 1915-2014. March 1947 is not included because of incomplete data.

The long-term average afternoon temperature in March for Tauranga is 22.5 degrees Celsius, ranging from the cool March months of 1960 with an average afternoon temperature of 20.4 degrees Celsius, and 1940 with an average afternoon temperature of 20.8 degrees Celsius, to the warm March months of 1916 (24.7 degrees Celsius), and 1938 and 1968 (24.6 degrees Celsius).

The graph of the average afternoon temperatures for March shows generally normal variations from March to March.

From 1915 to 2014, there have been five March months with an average afternoon temperature of 24 degrees Celsius or more, and 10 March months with an average afternoon temperature of 21.5 degrees Celsius or less.

The five warmest March months – in terms of average afternoon temperatures on record –in chronological order are: 1916, 1938, 1968, 2010 and 2013.

In contrast the 10 coolest March months – in terms of afternoon temperatures on record –in chronological order are: 1936, 1940, 1945, 1949, 1960, 1974, 1976, 1992, 1993 and 1998.

The average afternoon temperature for March for the 48 years from 1914-1962 was 22.4 degrees Celsius, compared with an average of 22.6 degrees Celsius for the 48 years from 1963-2011.

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Arctic and Antarctica Ice

Weather Eye
with John Maunder

Arctic sea ice reached its annual maximum extent for 2014 on March 21. Overall, the 2014 Arctic sea ice coverage was the fifth lowest in the 1978-2014 record.

In contrast, Antarctic sea ice reached its annual minimum for 2014 on February 23. This is the fourth highest Antarctic minimum in the satellite record. This continues a strong pattern of greater-than-average sea ice extent in Antarctica for the last two years.

The National Snow and Ice Data Centre, in Boulder, Colorado, has an extensive website on Arctic and Antarctic sea ice.

Graphs of the extent of the Northern Hemisphere and Southern Hemisphere ice – updated to March, 2014 – from the above website are shown below.

These show from 1979 to 2011 the Northern Hemisphere ice extent decreased at the rate of 2.6 per cent per decade, compared with an increase of 4.5 per cent per decade during the same period in the Southern Hemisphere.

However, the Southern Hemisphere shows a relatively large variability compared with that for the Northern Hemisphere.


 

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Tauranga’s April Rainfalls 1898-2014

 
Weather Eye
with John Maunder

Rainfalls in Tauranga during the month of April 2014 and April 2013 were both relatively wet, with April 2013 recording 284mm – the sixth highest April rainfall since 1898 – and last month tallying 225mm – the 17th highest April rainfall in the city since 1898.

The graph shows the range of rainfalls from a high of 383mm in 1911 to a low of 10mm in 1958.

The second wettest April was 1948, when 333mm was recorded; and the second driest was April 2010 with only 12mm. The long-term average rainfall for Tauranga for April is 120mm.

Since 1898, there have been 10 April months with a rainfall of 250mm or more. In chronological order, the wettest April months are: 1911, 1923, 1935, 1938, 1948, 1959, 1995, 2000, 2001, and 2013.

In terms of dry April months, there have been nine months with rainfall of 30mm or less. In chronological order, the driest April months are: 1898, 1910, 1913, 1919, 1958, 1979, 1984, 2005, and 2010.

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Tauranga’s Average April Afternoon Temperatures 1913-2014


Weather Eye
with John Maunder

Temperatures have been recorded in the Tauranga area at several sites during the last 100 years, including the current Tauranga Airport site from June 1990.

It is very common for areas such as Tauranga to have had different observation sites during the years – and the readings from the earlier sites have been adjusted to the present site using standard climatologically procedures.

It is considered the temperature series described here is a fair and true record of what the temperature would have been if the current observation site (Tauranga Airport) had been used throughout the period.

The temperature series, as shown in the graph, are based on the data from the original observations from the various sites as available on the NIWA National Climate Database archive, with data from the sites prior to the Tauranga Airport site being adjusted, where appropriate, to temperatures which are likely to have been recorded at the current airport site.

Traditionally, temperature observations have been recorded with a set of maximum and minimum temperature thermometers. These record the daily maximum temperature (usually recorded in mid-afternoon), and daily minimum temperature (usually recorded just before dawn).

The graph shows details of the average daily maximum temperatures (called simply ‘afternoon'), for Tauranga for April from 1914-2014. Note April 1947 and 1964 are not included because of incomplete data.

The long-term average afternoon temperature in April for Tauranga for is 20 degrees Celsius, ranging from the cool April months of 1925, with an average afternoon temperature of 18.2 degrees Celsius, and 1923 with an average afternoon temperature of 18.3 degrees Celsius, to the warm April months of 1938 (22.5 degrees Celsius), and 1916 (22.4 degrees Celsius).

The graph of the average afternoon temperatures for April shows generally normal variations from April to April, with several of the last 15 Aprils being a little warmer than other April months.

From 1914 to 2014, there have been 13 April months with an average afternoon temperature of 21.0 degrees Celsius or more, and eight April months with an average afternoon temperature of less than 19.0 degrees Celsius.

The value for April 2014 was 21.6 degrees Celsius.

The 13 warmest April months – in terms of afternoon temperatures – on record, in chronological order, are 1916, 1924, 1928, 1935, 1938, 1948, 1955, 1956, 1978, 1981, 2012, 2013 and 2014.

In contrast, the eight coolest April months – in terms of afternoon temperatures – on record, in chronological order, are 1923, 1925, 1940, 1941, 1949, 1980, 1991 and 1992.

The average afternoon temperatures for Tauranga for the 50 years 1914-1962, and the 50-year period 1963-2011 are both 20 degrees Celsius.

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Tropospheric Global temperatures - January 1979 to April 2014


Weather Eye
with John Maunder

The latest global average temperatures of the troposphere - those observed from NOAA satellites, are computed by the University of Alabama at Huntsville, in the United States.
 
The troposphere is the lowest portion of Earth's atmosphere.  The average depth of the troposphere is approximately 17 km in the middle latitudes. The word troposphere derives from the Greek tropos for "change" reflecting the fact that turbulent  mixing plays an important role in the troposphere's structure  and behaviour. Most of the phenomena we associate with the day-to-day weather occur in the troposphere.
 
The chart shows that since 1979, when reliable satellite observations have been available, there has been little overall trend ( from the average temperatures over the 30 year period 1981 – 2010  in the temperatures in troposphere ( apart from  "normally expected " variations), except for a small warming trend.
 

 
The data for 2011 are: January 0.00 degrees, February -0.02, March -0.10, April +0.12, May +0.14, June +0.32, July +0.38, August +0.33, September +0.29, October +0.12, November +0.12, December +0.10 degrees C.
 
The data for 2012 are: January -0.09 degrees, February -0.12, March +0.11, April +0.29, May +0.29, June +0.37, July +0.28, August +0.34 , November +0.28, December +0.20 degrees C.
 
The data for 2013 are: January +0.50 degrees, February +0.18, March +0.20, April +0.10, May +0.07, June +0.30, July +0.17, August +0.16,  September +0.37, October +0.29, November +0.19, December +0.23 degrees C.
 
The data for 2014 are: January +0.29 degrees, February +0.17 degrees, March +0.17 degrees, and April +0.19 degrees C.

The coolest months (since 1979) were September 1984 (-0.49 degrees C) and November 1984 (-0.42 degrees C), and the warmest months were February and April 1998 (both +0.76 degrees C). The chart shows the “El Nino” warming in the 1998 period and the Mount Pinatubo (volcanic) cooling during the 1992-1993 period.

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Climate Change – Methods of Inferring/Detecting Changes


What causes the climate to change as well as understanding the methods for detecting changes in the climate are on-going research activities.

The following is a brief summary of the methods scientists and others, such as historians, employ in inferring and detecting changes in climate during a variety of time scales. I'm indebted for a website from NIWA for much of this summary.

Instrumental measurements

Data from instruments and written or oral records provide quantitative records of temperature and other meteorological records for the last 150 years in New Zealand – and up to 350 years in a few other countries such as summer, winter, and annual temperature charts for central England from 1660-2013 shown in the graph.

Such records must be analysed carefully, to identify the influence of any non-climate factors, such as changes in observing site or method, or encroaching urban development. Records of sea level and land movements are also important for assessing sea level change.

Proxy data

Beyond the scope of instrumental measurements, information about past climate can be obtained from natural proxy archives, as well as historical records of events, such as harvests etc.

Changes observed in these archives often identify so closely to climate variations they can be used as a substitute for climate records prior to the instrumental record after a careful calibration process has been undertaken.

Piecing evidence together from various natural proxy data sources includes:

Ice cores

Ice cores drilled in Greenland, the Antarctic ice sheets, the Himalayas, and in other alpine regions of the world comprise very important archives because they provide extensive detailed information about past climate variability and atmospheric composition

The ratio of oxygen isotopes in ice can indicate the temperature at the time ice was deposited as snow. Air bubbles can be analysed to measure atmospheric carbon dioxide and methane concentrations at the time the bubbles were trapped in the ice.

Dust trapped in the ice may indicate windy, arid conditions. Geochemistry, including trace elements and salts, can tell a story about regional atmospheric circulation. The core from the Russian Rostock station in Antarctica provides information back to at least 160,000 years ago, and when drilling is completed a climate record of the last 500,000 years is probable.

Fossil pollen and phytoliths

Different classes of plants produce pollen grains and phytoliths (siliceous formations precipitated by plants) that have distinctive shapes. Pollen grains and phytoliths are often found preserved in sediment cores from ponds, lakes and marine environments.

Lake sediments

Composition and sedimentation rates in lakes change in response to variations in environmental conditions during periods of wet and dry climate. Pollen in the sediments can indicate the type of vegetation present, and plankton biota indicates physical and chemical conditions in the lake water. In some cases, stark seasonal changes in lake inflows and sedimentation can cause annual layers to form in lake sediments.

Annual layers, or varves, commonly form in lakes fed by glacial meltwater, and can be used to infer the amount of melted ice and what past warm season temperatures were like. Within the sediment layers, microfossils like diatoms, bugs, and plant material are preserved. These fossils can also reveal information about what past environmental conditions were like, sometimes with incredible precision.

Ocean sediment cores

These cores contain primitive shelled animals (foraminifera) whose abundance in the surface layers of the ocean depends on surface water temperature and other conditions. Off New Zealand the rate and type of sediment deposition depends on factors such as the amount of glacial activity and on other climate-driven erosion processes.

Pollen types and the isotopic composition of material in the sediments provide further information on past climates. Cores obtained off New Zealand from the international deep sea drilling project provide information as far back as 6.3 million years, and drilling of more cores is planned.

New Zealand is coordinating an interesting international drilling project near Cape Roberts in Antarctica, to establish more information about past Antarctic climate and ice extent.

Loess

Loess are fine-grained wind-blown dust deposits on land. They typically accumulate during periods characterised by dry and windy conditions. In New Zealand, they are associated with cool and cold intervals that coincide with glacial advances. Numerous loess sections can be found on the South Island, particularly in eastern regions.

Glaciers

Variations in the past size of glaciers can be inferred from the location of moraines (rocks and debris deposited by glaciers that mark a former ice margin position), outwash fans, buried soils, and by the presence of glacial features in the landscape. In New Zealand, cool summer temperatures are only one factor in promoting ice accumulation on glaciers, and snow accumulation rates also respond to changes in the strength and direction of the westerly wind flow and sea level pressure in summer.

Speleothems

Speleothems are used to describe a stalactite, stalagmite or flowstone cave deposit of crystalline nature. These deposits occur within karst terranes in subterranean caverns mainly as calcite precipitated from groundwater that percolated through overlying limestone or marble rock.

Tree rings

Tree rings are some of the best resolved records of past climate in the world. This is because, in many cases, one tree ring is grown each year, allowing tree rings to be dated with great precision and with annual resolution.

Tree growth is dependent on many factors. However, common growth patterns often emerge at the regional scale between trees, suggesting there is a common growth response to climate changes. Correlations of tree ring data with soil moisture, temperature, and precipitation often enable tree ring records to be substituted for instrumental climate data into the distant past.

In the case of NZ, which has many long lived tree species suitable for dendrochronology, long climate reconstructions of droughts, storms, and even El Nino events are possible.

Boreholes

It is sometimes possible to deduce past surface temperatures going back several hundred years by measuring the way temperature varies with depth in a borehole several hundred metres deep (at a suitable site not disturbed by groundwater flow). This is because fluctuations in ground surface temperatures propagate slowly downwards into the earth as a “temperature wave”.

- See more at: http://www.sunlive.co.nz/blogs/6532-climate-change-methods-of-inferringdetecting-changes.html#sthash.OYayFvSl.dpuf