MODELING STUDIES ON THE AUSTRALIAN SUMMER MONSOON

The ability of the Bureau of Meteorology Research Centre global spectral model to simulate features of the Australian summer monsoon during January and February 1987 has been studied. Two timescales were considered: namely, the short range, defined by periods of less than 5 days, and the long range (30-40 days). It is shown that the mean circulation and precipitation simulated by the model are sensitive to the sea surface temperature. However, this sensitivity is realized only if appropriate parameterizations of boundary layer fluxes are used. The short-term predictions of monsoon onset are sensitive to the initial moisture analysis and the parameterization of cumulus convection.