Trends in extreme daily temperature and rainfall have been analysed from 1961 to 1998 for Southeast Asia and the South Pacific. This 38-year period was chosen to optimize data availability across the region. Using high-quality data from 91 stations in 15 countries, significant increases were detected in the annual number of hot days and warm nights, with significant decreases in the annual number of cool days and cold nights. These trends in extreme temperatures showed considerable consistency across the region. Extreme rainfall trends were generally less spatially coherent than were those for extreme temperature. The number of rain days (with at least 2 mm of rain) has decreased significantly throughout Southeast Asia and the western and central South Pacific, but increased in the north of French Polynesia, in Fiji, and at some stations in Australia. The proportion of annual rainfall from extreme events has increased at a majority of stations. The frequency of extreme rainfall events has declined at most stations (but not significantly), although significant increases were detected in French Polynesia. Trends in the average intensity of the wettest rainfall events each year were generally weak and not significant.

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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 link between monsoonal activity and tropical cyclones. The problems related to the above mentioned topics and their research priorities are highlighted.