Characteristics of Australian Land Surface Temperature Variability

Summary

 A study of the variability of Australian surface maximum and minimum temperature on seasonal and longer time scales for the period 1950 to 1994 is described. Using principal component analysis in the S-mode, it is shown that the variability of Australian temperature is dominated by the large scale, with approximately 80 percent of the temporal variance being explained by five independent modes. The application of orthogonal rotation techniques to these modes, has revealed that this variability displays much simple structure and is physically interpretable in terms of five largely non-overlapping spatial patterns. These five patterns, centred over the east, north, southwest, northwest and southeast of Australia are found when the analysis is performed on maximum and minimum temperature, using monthly, seasonal and annual data and appear to be a natural and optimal subdivision of the Australian region for the description of land surface temperature variability.

The highly compressed description of the temperature data provided by the rotated principal component modes is then used to investigate the characteristics and some mechanisms of Australian temperature variability. This analysis confirms the presence of a secular warming trends across much of Australia, but also reveals that some 80 to 90 percent of the temporal variance is unrelated to this trend. The role of rainfall and the El Niño-Southern Oscillation (ENSO) in modulating temperature is also investigated.