Australian rainfall patterns and the southern oscillation. 1. A continental perspective

Abstract

Various Australian rainfall records have been subjected to filter-analysis. The results represent an extension of the findings of Currie and Vines (1996) in their analyses of more than 300 annual rainfall-series gathered from weather stations widely spaced across the continent. Further evidence is presented for the existence of "cyclic" variations in precipitation with periods of 16?20 years and 10?11 years. Links are suggested with the luni-solar cycle of 18.6 years and the sunspot cycle of nominal period 10?12 years. A shorter "cycle" of 6?7 years is also postulated. Similar analyses of yearly data for the Southern Oscillation yield further suggestions of "cycles" that correspond closely with those obtained from the rainfall records. Explanations are proposed which appear to account for a substantial proportion of the interannual variability of rainfall, particularly in eastern Australia - with connections being made between EI Niño/Southern Oscillation events and the incidence of drought in various parts of the continent. A major implication is that a variety of climatic effects in different parts of the world can be largely ascribed to the influence of the (18.6 year) luni-solar cycle.