East Australian rainfall events: interannual variations, trends, and relationships with the Southern Oscillation

Abstract

The number, average length, and average intensity of rain events at five stations located in eastern Australia have been calculated for each year from 1910 to 1988, using daily rainfall totals. A rain event has been defined as a period of consecutive days on which rainfall has been recorded on each day. Annual rainfall variations are found to be primarily caused by variations in intensity. Fluctuations in the three rain-event variables are essentially independent of each other. The large-scale geographical nature of east Australian rainfall fluctuations mainly reflects interstation correlations in the number of events. The El Nino-Southern Oscillation affects rainfall mainly by influencing the number and intensity of rain events. Twentieth century increases in east Australian rainfall have been due, primarily, to increased numbers of events. Intensity of rain events has generally declined, offsetting some of the increase in rainfall expected from more frequent events. -from Authors