THE CLIMATE WEATHER EYE

25
  
 
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 November, 19, 2018

The Weekend Sun ( New Zealand) is published each Friday 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.

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

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WEATHEREYE # 289

Tropospheric Temperatures 1979 to October 2018

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 October 2018 - 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 latest data for October 2018 is +0.22 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.

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The physicist Leo Szilard once announced to his friend Hans Bethe that he was thinking of keeping a diary: 'I don't intend to publish, I am merely going to record the facts for the information of God.' 'Don't you think God knows the facts?' Bethe asked. 'Yes' said Szilard. ‘He knows the facts, but he does not know THIS version of the facts'

"(From Hans Christian von Baeyer, "Taming the Atom" (from the preface paragraph in "A Short History of Nearly Everything", by Bill Bryson, A Black Swan Book, 2004)

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



Tauranga October Average Afternoon Temperatures 1913-2018

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 1913-2018.

The average afternoon temperature for October 2018 for Tauranga was 19.3 degrees C, which was the equal sixth warmest on record.

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 2018, there have been fifteen 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.

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

The physicist Leo Szilard once announced to his friend Hans Bethe that he was thinking of keeping a diary: 'I don't intend to publish, I am merely going to record the facts for the information of God.' 'Don't you think God knows the facts?' Bethe asked. 'Yes' said Szilard. ‘He knows the facts, but he does not know THIS version of the facts'

"(From Hans Christian von Baeyer, "Taming the Atom" (from the preface paragraph in "A Short History of Nearly Everything", by Bill Bryson, A Black Swan Book, 2004)

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



Tauranga October Rainfalls 1898-2018

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 2018 was 79 mm.

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

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




Arctic and Antarctic Temperatures ..... January 2000 to August 2018

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:

 

https://www.climate4you.com/Text/Climate4you

 

One example of what is contained in his web base is a chart of Arctic and Antarctic surface air temperatures from January 2000 to August 2018.

Note.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.

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

Global Temperatures 1996 – August 2018

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- August 2018. The black line shows meteorological stations only; the dotted line is the land-ocean temperature index obtained from satellite measurements.

For details see data.giss.nasa. (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 1997 to August 2018 there has been 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 wide range of climate matters see:https://sites.google.com/site/climatediceandthebutterfly/




Sea Level Changes

Weather Eye
with John Maunder

Global (or eustatic) sea-level change is measured relative to an idealised reference level, the geoid, which is a mathematical model of planet Earth’s surface. Global sea-level is a function of the volume of the ocean basins and the volume of water they contain. Changes in global sea-level are caused by – but not limited to - four main mechanisms:

Source: www.climat4you.com

1. Changes in local and regional air pressure and wind, and tidal changes introduced by the Moon.

2. Changes in ocean basin volume by tectonic (geological) forces.

3. Changes in ocean water density caused by variations in currents, water temperature and salinity.

4. Changes in the volume of water caused by changes in the mass balance of terrestrial glaciers.

In addition to these there are other mechanisms influencing sea-level; such as storage of ground water, storage in lakes and rivers, evaporation, etc.

Mechanism 1 is controlling sea-level at many sites on a time scale from months to several years. As an example, many coastal stations show a pronounced annual variation reflecting seasonal changes in air pressures and wind speed. Longer-term climatic changes playing out over decades or centuries will also affect measurements of sea-level changes.

Mechanism 2 – with the important exception of earthquakes and tsunamis - typically operates over long (geological) time scales, and is not significant on human time scales. It may relate to variations in the sea-floor spreading rate, causing volume changes in mid-ocean mountain ridges, and to the slowly changing configuration of land and oceans.

Mechanism 3 (temperature-driven expansion) only affects the uppermost part of the oceans on human time scales. Usually, temperature-driven changes in density are more important than salinity-driven changes. Seawater is characterised by a relatively small coefficient of expansion, but the effect should however not be overlooked, especially when interpreting satellite altimetry data. Temperature-driven expansion of a column of seawater will not affect the total mass of water within the column considered and will therefore not affect the potential at the top of the water column. Temperature-driven ocean water expansion will therefore not in itself lead to lateral displacement of water, but only lift the ocean surface locally.

Mechanism 4 (changes in glacier mass balance) is an important driver for global sea-level changes along coasts, for human time scales. Volume changes of floating glaciers – ice shelves – has no influence on the global sea-level, just like volume changes of floating sea ice has no influence. Only the mass-balance of grounded or land-based glaciers is important for the global sea-level along coasts.

Summing up: Mechanism 1 and 4 are the most important for understanding sea-level changes along coasts.

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


Tauranga September Average Afternoon Temperatures 1913-2018

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 1913-2018.

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 2018 was 17.2 degrees C.

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.

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




Tauranga September Rainfalls 1898-2018

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 seven September months with a rainfalls of 40 mm or less.

The rainfall for September 2018 was 34 mm.

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 twelfth driest September months (rainfalls of 50 mm or less) are 1910, 1913, 1914, 1921, 1922, 1944, 1965, 1993, 1987, 2006, 2011 and 2018.

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/



Sunspots and the Sun

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 10.

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 seven years into solar cycle 24. This is the smallest sunspot cycle since solar cycle 14 which had a maximum of 64.2 in February of 1906.

Spotless Days

Since mid-2016, the Sun has occasionally been devoid of sunspots. These spotless disks will gradually become a familiar feature as the solar cycle is heading for its next minimum, currently expected by the end of this decade. The number of spotless days can vary significantly from one solar cycle transit to another. For example, during the previous minimum (around 2008), no less than 817 spotless days were recorded, whereas the minimum period leading into solar cycle 23 (around 1996) counted only 309 such blemishless days.

As the current solar cycle 24 will gradually give way to the new solar cycle 25, several consecutive days and even weeks without sunspots will become the norm. In order to have an idea on the number of spotless days, and how these numbers compare to past solar cycles, the SILSO web site has created a “Spotless Days page”. This page contains graphs and tables on the accumulated number of spotless days, stretches of spotless days, and comparisons to other solar cycles – all supplemented with a word of explanation.

The previous minimum surprised scientists and solar observers by being the deepest in nearly 90 years. Will the upcoming solar cycle minimum show as many spotless days, or will solar cycle 25 take off much faster than expected? The “Spotless Days page” will provide you with a front-row seat on the current status of the solar cycle minimum and the number of spotless days. Enjoy! Perhaps a new “Maunder Minimum” era is upon us!



Tropospheric Temperatures 1979 to August 2018

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 January 2018 - 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, September +0.54 degrees C, October +0.63 degrees C, November +0.50 degrees C, and December +0.30 degrees C.

The data for 2018 is: January +0.26 degrees C. February +0.20, March +0.24, April +0.21, May +0.28, June +0.23, July 0.32 , and August +0.19 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 for information see: https://sites.google.com/site/climatediceandthebutterfly



Tauranga August Average Afternoon Temperatures 1913-2018

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 1913-2018. The average for August 2018 was 15.6 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.

From 1913 to 2018, 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 1914-1963 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/theweatherclimateeye/





Tauranga August Rainfalls 1898-2018

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 2018 was 140 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 see: https://sites.google.com/site/theweatherclimateeye/



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 graph below ( from the Australian Bureau of Meteorology) shows monthly values of the SOI from 1880 to early August 2018..

The El Niño–Southern Oscillation (ENSO) is currently neutral. While the tropical Pacific Ocean has cooled in the past month, most international climate models forecast warming to resume in the coming weeks, with El Niño development possible in the Southern Hemisphere spring. Therefore, the Bureau's ENSO Outlook remains at El Niño WATCH. El Niño WATCH means there is approximately a 50% chance of El Niño forming in 2018; double the normal chance.

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/




Tropospheric Temperatures 1989- July 2018

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 July 2018 - 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, September +0.54 degrees C, October +0.63 degrees C, November +0.50 degrees C, and December +0.30 degrees C.

The data for 2018 is January +0.26 degrees C, February + 0.20 degrees C, March + 0.24 degrees C, April +0.21 degrees C, May +0.28 degrees C, June +0.23 degrees C, and July +0.32 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: Average July Afternoon Temperatures 1913-2018

Weather Eye
with John Maunder

The graph below shows details of the average daily maximum temperatures, called ‘afternoon', for Tauranga for July from 1913-2018. The temperature for July 2018 was 15.1 degrees Celsius.

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 2018, there have been 6 July months with an average afternoon temperature of 15.2 degrees Celsius or more, and 11 July months with an average afternoon temperature of less than 13.3 degrees Celsius.

The 6 mildest July months for afternoon temperatures on record, in chronological order are: 1915, 1916, 1917, 1984, 1998, and 2000..

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.

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





Tauranga July Rainfalls 1898-2018

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 1898-2018 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 2018 was 93 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/nzrainfalls/newzealandmonthlyrainfalls




Yearly Temperatures in England 1700-2018

Weather Eye
with John Maunder

Yearly mean temperatures have been recorded in Central England since about 1700. It is the longest temperature series in the world derived from instrumental records. It shows an increase in temperature of approximately 1.3°C degrees from the end of the 17th Century to the end of the 20th Century/beginning of 21st Century. Subtle difference in timing between the warming/cooling phases between the Central England record and the other localities may reflect local climate variation, but the similarity in events between continents suggests the Central England Temperature record is recording global temperature patterns.

Records of sunspot numbers began in 1610 such that detailed estimates of solar variation for the years covered by the England temperature record can be made without resort to the use of proxy data. Reconstructions of total solar radiance (TSR) differ in magnitude, but there is agreement in form with 4 peaks and 4 to 6 troughs occurring over the time-scale of the England temperate record These are: a minimum in TSR associated with the Maunder Sunspot Minimum in the latter half of the 17th Century; a peak, possibly bi-modal approaching modern TSR values during the 18th Century; a well-defined trough corresponding with the Dalton Sunspot Minimum between 1800- 1820; a poorly defined TSR peak in the mid 19th Century; a reduction in TSR during the late 19th Century; increasing TSAR during the early 20th Century; a decrease in TSR from around 1950- 1975; and a second phase of TSR increase in the late 20th Century.

There is good correspondence with TSR throughout the England temperature record, with warm events correlating with high TSR and cool phases correlating with plateaus or decreases in TSR. However, for temperature increases from the beginning of the Industrial Revolution (Maunder Minimum and Dalton Minimum to end of 20th Century), high TSR models can account for only 63-67% of the temperature increase. This would suggest that one third of Global Warming/Climate Change can be attributed to anthropogenic global warming. Approximately two-thirds [0.8°C to 0.9°C] of climate warming since the mid-late 18th Century [1.3°C] can be attributed to solar causes, suggesting warming due to anthropogenic causes over the last two centuries is 0.4 to 0.5°C.

Source Alan D Smith

“An Analysis of Climate Forcing's from the Central

England Temperature Record”

British Journal of Environment & Climate Change

7(2): 113-118, 2017

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


Tropospheric Temperatures 1989 - June 2018

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 2018- 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 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, September +0.54 degrees C, October +0.63 degrees C, November +0.50 degrees C, and December +0.30 degrees C.
  •  
  • The data for 2018 is January +0.26 degrees C, February + 0.20 degrees C, March + 0.24 degrees C, April +0.21 degrees C, May +0.23 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.

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




Sunspots and the Maunder Minimum Revisited

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 20, and for the 16 days to July 16, 2018 here have been no sunspots.

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 seven 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.

Spotless Days

Since mid-2016, the Sun has occasionally been devoid of sunspots. These spotless disks will gradually become a familiar feature as the solar cycle is heading for its next minimum, currently expected by the end of this decade. The number of spotless days can vary significantly from one solar cycle transit to another. For example, during the previous minimum (around 2008), no less than 817 spotless days were recorded, whereas the minimum period leading into solar cycle 23 (around 1996) counted only 309 such blemishless days.

As the current solar cycle 24 will gradually give way to the new solar cycle 25, several consecutive days and even weeks without sunspots will become the norm. In order to have an idea on the number of spotless days, and how these numbers compare to past solar cycles, the SILSO web site has created a “Spotless Days page”. This page contains graphs and tables on the accumulated number of spotless days, stretches of spotless days, and comparisons to other solar cycles – all supplemented with a word of explanation.

The previous minimum surprised scientists and solar observers by being the deepest in nearly 90 years. Will the upcoming solar cycle minimum show as many spotless days, or will solar cycle 25 take off much faster than expected? The “Spotless Days page” will provide you with a front-row seat on the current status of the solar cycle minimum and the number of spotless days. Enjoy! Perhaps a new “Maunder Minimum” era is upon is!

For further information see: https://sites.google.com/site/johnmaunder/the-maunder-minmium---300-years-on




Tauranga June Average Afternoon Temperatures 1913-2018

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 1913-2018.

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 C.

June 2014 had an average afternoon temperature of 16.9 degrees Celsius was the warmest June on record since observations were first made in 1913. The temperature in June 2018 was a relatively cool 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 2018, 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 ninth ‘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.

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






Weather and Philately

Weather Eye
with John Maunder

On July 1, 2016 (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.

For further information on a variety of weather topic see: https://sites.google.com/site/theweatherclimateeye/

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

Villach 1985 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. The Australian SKY TV programmme has each weekday the Andrew Bolt programme which very often has an item on climate which is generally in contact to what we see or read about in NZ.

Thirty or twenty yaers 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.

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

https://www.sunlive.co.nz/blogs/12192-villach-1985-and-climate-change.html





Tauranga May Average Afternoon Temperatures 1913-2018

Weather Eye
with John Maunder

The average afternoon temperature in Tauranga in May 2018 was 18.1 degrees C.

In contrast, May 2016 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 2018, 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.

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


Tauranga May Rainfalls 1898-2018

Weather Eye
with John Maunder

Apart from the exceptional rainfall of 634 mm in May 2005, the graph shows a small decrease in overall May rainfalls over the last 120 years when two recent adjacent 50-year periods are compared. The rainfall for Tauranga for May 2018 was 71 mm.

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

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



Tropospheric Temperatures 1979 to April 2018

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 January 2018 - 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.

  1. 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, September +0.54 degrees C, October +0.63 degrees C, November +0.50 degrees C, and December +0.30 degrees C.
  2. data for 2018 is January +0.26 degrees C, February + 0.20 degrees C, and March + 0.24 degrees C, April +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.

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



Tauranga April Rainfalls 1898-2018

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.

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 2018 had a rainfall of 140 mm.

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.