Long-term variations in the Southern Oscillation and relationships with Australian rainfall

Abstract

Climatic eposides constituting the long-term variation of the Southern Oscillation (SO) are identified from accumulated Darwin mean sea level pressure (MSLP) anomalies. Features of the rainfall and pressure variations in these episodes are analysed. A bi-modal periodicity of two to three years and three to five years in the SO was found and areas of Australia showing significant rainfall variance corresponding to these two periods are defined. Darwin pressure anomalies are stratified into phases of a typical cycle of the oscillation in Darwin pressure and the evolution of rainfall anomalies associated with each phase is described. Frequencies of rainfall departures from the climatological average in each phase of the typical cycle in pressure departures are presented. -Authors