Influence of Indian Ocean sea-surface temperature variability on winter rainfall across eastern Australia

This study investigates the relationship between sea-surface temperature (SST) variability occurring over the Indian Ocean and winter rainfall variability in eastern Australia. Previous research has identified a number of modes of SST variability over the Indian Ocean that may be connected to rainfall variability in Australia. Six indices of SST variability are compared and their relationship to winter rainfall over eastern Australia is determined. It is shown that a strong relationship exists between a number of these indices and winter rainfall. Additionally, this relationship is shown to hold true irrespective of potential impacts on rainfall by the El Niño/Southern Oscillation (ENSO). A possible physical process by which Indian Ocean SST anomalies may influence winter rainfall in eastern Australia is proposed involving impacts on the nature of the Northwest Australian Cloud Band. This study demonstrates marked controls on winter climate variability comparable to that induced in summer by the better known ENSO processes, and hence offers improved understanding of year-round seasonal climates.