THE AUSTRALIAN SUMMER MONSOON - A REVIEW

The Australian summer monsoon influences the climate of the Australian tropics during the period from December to March. During this period, interannual and intraseasonal variations of rainfall associated with global-scale circulation anomalies strongly effect human life and economic activities in this region. Any changes in the global-scale circulation patterns in relation to changes in the heat balance components under enhanced greenhouse condition could alter monsoonal circulation characteristics and thus could bring serious impacts to human life in the monsoon-dominated region. To provide a basis for looking at changes in monsoonal characteristics under enhanced greenhouse condition, the current understanding of the Australian summer monsoonal circulation characteristics is reviewed here. Detailed information is given on the formation and the steady development of the Pilbara heat low over the northwestern part of Australia and the importance of the location of the monsoon shear line, active and break cycles of the monsoon, influence of South China Sea cold surges on monsoon activity, 40-50 oscillation in monsoon rainfall and winds and their link to El Nino/Southern Oscillation (ENSO) phenomenon, the influence of the ENSO phenomenon on rainfall on interannual time scales and the Mk between monsoonal activity and tropical cyclones. The problems related to the above mentioned topics and their research priorities are highlighted.