Influence of Temporal Modes of Atmospheric/Oceanic Variability in the Southern Hemisphere on Australian Hydroclimatic Variation.

An exploratory analysis of the relationship between Southern Hemisphere's (SH) atmospheric/oceanic variables and streamflow and precipitation variation in Australia is presented. A 2.5x2.5 degrees gridded data of 500mb and 700mb geopotential heights (Z500, Z700) for the SH, obtained from the US National Center for Environmental Prediction (NCEP) and the National Center for Atmospheric Research (NCAR) reanalysis, were used to characterize the atmosphere. Longer memory processes occurring in the ocean were represented by Kaplan's 5x5 degrees dataset of sea surface temperature (SST). Empirical Orthogonal Functions (EOF) of monthly, seasonal and annual variation of the Z500, Z700 and SST grids were correlated to Australian hydroclimatic variables at different lags. A contingency analysis between these variables was also included. Previous studies in New Zealand suggest that part of the variance of precipitation records is potentially predictable (beyond the limits of deterministic predictability). It is expected that our study will show significant links between circulation and oceanic patterns and hydroclimatic variation in Australia. The objective of this ongoing study is to provide a basis for long-range precipitation and streamflow forecasts throughout Australia. Future work will include the identification of synoptic circulation types with the purpose of defining generalized patterns (associated with particular hydroclimatic conditions in Australia) than can be linked to analogous circulation patterns in the future using linear (regression) and non-linear models (e.g. self-organizing maps, map analysis, artificial neural networks).