Seasonal Effects Examples

The largest amount of sea ice at the North Pole normally occurs during February and March when the amount of sea ice is approximately 4 million square kilometres above the long term trend. Between April and August there is a consistent drop from month to month as temperatures are rising. The smallest amount of sea ice regularly occurs in September where the amount of sea ice is approximately 5 million square kilometres below the long term trend. After this the temperatures start cooling down again increasing the amount of ice on a month to month basis until it returns to its peak in February and March.

The seasonal pattern for male live births is not very consistent. On average the highest number of births occurs in the first quarter (January to March) where there are approximately 230 more births than the long term trend. The lowest on average occurs in the fourth quarter (October to December) where there are approximately 150 births less than the long term trend, however there are many years that it does not follow this pattern.

There is a consistent seasonal pattern for the population of penguins on Philip Island. There are clear highs of approximately 450 penguins above the average every December. The population then starts to reduce until it reaches a low of about 250 animals less than the average in March before climbing again to about 150 more than the average in May. Numbers rapidly decline again to about 330 penguins less than the average in June. Penguin numbers then gradually increase to its highs in December.

The number of visitors arriving here from Australia follows a simple quarterly pattern. There is a distinctive high in the first quarter where 8000 more visitors than the average arrive. This number then takes a sharp dive to its yearly low of about 6000 less than the average in the second quarter before gradually increasing back to its high in the first quarter.

The seasonal variation of this data set is not regular. There does not appear to be a consistent seasonal pattern, apart from the fact that there is a regular low in January where Total Airport CIF is approximately $150,000,000 less than the average and a regular high in November where Total Airport CIF is approximately $90,000,000 more than the average.

This pattern would appear to be related to the shopping habits associated with Christmas. A large increase in imports in November would coincide with retailers stocking up for Christmas. And a large reduction in imports in January would coincide with the lack of imports by retailers as they, instead, try and sell off their existing stocks in post-Christmas and New Years sales.

The seasonal variation of this data set is reasonably regular. There is a regular low in the first quarter of every year where the amount of harvested timber from plantation forests is just over 400 million m³ than the average. We then see a lot of harvesting during the 2nd and 3rd quarters of every year where approximately 200 and 230 million m³ of wood more than the average is harvested.

Harvesting appears to be done more in the winter months than summer or spring. This may be because trees grow quicker in Summer and Spring and therefore it would be better to harvest them after this stage to get more wood.