Australia: The Land Where Time Began

A biography of the Australian continent 

Seasonal extremes over Australia - Influence of Climate Variability

The climate of Australia is known to be affected by natural climate variability, by such events as El Niņo-Southern Oscillation (ENSO), the Indian Ocean Dipole (IOD) and the Southern Annular Mode (SAM), and of these the one it is affected by at any particular time depends on the season and region in question. There have been limited studies on climate extremes in Australia that are associated with natural climate variability. In this study the authors1 concentrated on the impact of climate variability on the interannual changes in seasonal extremes of rainfall and temperature throughout Australia from 1957-2010. Non-stationary Generalised Extreme Value (GEV) analysis was used, where GEV values were specified in a linear function of climate variability modes, and the authors1 compared their results with the case in which the variability of the climate is not considered. It was consistently suggested by the results from 2 station-based observational data sets that extreme responses overall resemble mean responses to climate variability. During El Niņo events anomalously hotter and drier conditions occur over northeastern Australia and the southern coast and a positive Indian Ocean Dipole phase (pIOD) in cold seasons, and during La Niņa events and the negative phase of the IOD wetter, cooler conditions were observed. Over much of the eastern part of the continent in summer a positive (negative) phase of the SAM is associated with wetter, cooler (warmer and drier) conditions. It was also found that covariation and the importance of ENSO and the IOD, as well as an inverse relationship between rainfall and the daily temperature maximum were also found to hold for extremes. It is suggested by this that teleconnections that are responsible for seasonal mean variations may be involved in interannual changes in extremes, which provides important implications for climate model evaluations and projected changes in regional climate change.

Sources & Further reading

  1. Min, Seung-Ki, Wenju Cai, and Penny Whetton. "Influence of Climate Variability on Seasonal Extremes over Australia." Journal of Geophysical Research: Atmospheres (2013): n/a-n/a.
Author: M. H. Monroe
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