Multi-decadal variability of rainfall and streamflow across eastern Australia

This study investigates the influence of the El Nino/Southern Oscillation (ENSO) and the Interdecadal Pacific Oscillation (IPO) on rainfall and streamflow regimes of eastern Australia. An analysis of historical rainfall and streamflow data for Queensland (QLD), New South Wales (NSW) and Victoria (VIC) reveals strong relationships between these indices and seasonal rainfall and streamflow totals. Rainfall and streamflow in NSW and QLD are shown to be significantly enhanced during the La Nina phase of ENSO, with La Nina impacts diminishing as one moves south into VIC. In addition, the study shows that on a multi-decadal time scale, the negative phase of the IPO is associated with "wetter" conditions than the positive phase. Importantly, the already enhanced La Nina rainfall and streamflow is demonstrated to be even further magnified during La Nina events that occur in the IPO negative phase. The results also indicate that some useful predictability of ENSO impacts can be achieved during the negative phase of the IPO for VIC