Geophysical Research Letters

Southern Australian rainfall and the subtropical ridge: Variations, interrelationships, and trends



[1] Monthly values of the latitude and intensity (mean maximum pressure) of the subtropical ridge (STR), averaged across Australian longitudes (105–155°E), have been related to variations and trends in rainfall over southern Australia (south of 30°S), for 1958–2005. There is an abrupt shift of latitude of the subtropical ridge over Australia at the onset of winter. In the cooler part of the year the intensity of the STR is more closely related to rainfall variations (and correlations between latitude and rainfall are a by-product of the relationship of intensity with both latitude and rainfall), whereas in summer the latitude of the STR is more closely related to rainfall. The decline in southern Australian rainfall in recent decades (which has occurred principally in autumn) appears related to a trend towards a more intense STR, rather than a trend in the latitude of the STR.