ENSO and the Interdecadal Pacific Oscillation: their impact on Australian rainfall

The spatial and temporal impact upon Australian rainfall/ENSO relationships by an inter-decadal oscillation in surface temperature of the Pacific Ocean has been examined by analysing a high resolution (0.25degree x 0.25degree) seasonal rainfall dataset. It is shown that for seasons when the Inter-decadal Pacific Oscillation (IPO) lowers the surface temperature of the Pacific Ocean there is a stronger relationship between ENSO and Australian rainfall then when the IPO raises Pacific Ocean temperatures. Largest differences in the relationship occur in southern and eastern Australia during the Austral Spring. These findings highlight the contrasting impact of ENSO during the two phases of the IPO, and hence may provide a means for improved seasonal climate prediction.