Inter-decadal modulation of the impact of ENSO on Australia

The success of an ENSO-based statistical rainfall prediction scheme and the in#uence of ENSO on Australia are shown to vary in association with a coherent, inter-decadal oscillation in surface temperature over the Paci"c Ocean. When this Inter-decadal Paci"c Oscillation (IPO) raises temperatures in the tropical Paci"c Ocean, there is no robust relationship between year-to-year Australian climate variations and ENSO. When the IPO lowers temperature in the same region, on the other hand, year-to-year ENSO variability is closely associated with year-to-year variability in rainfall, surface temperature, river #ow and the domestic wheat crop yield. The contrast in ENSO's in#uence between the two phases of the IPO is quite remarkable. This highlights exciting new avenues for obtaining improved climate predictions.