SIMULATED CHANGES IN EXTREME RAINFALL OVER SOUTHERN AFRICA

A general circulation model simulation is used to investigate possible changes in rainfall over southern Africa resulting from a doubling of atmospheric carbon dioxide. Simulated increases in rainfall intensity are found to be a spatially coherent and an apparently less regionall y dependent signal of climatic change than changes in annual means or number of I-din-days. Accordingly, increases in both the frequency and intensity of extreme daily rainfall events are simulated throughout m ost of the subcontinent. Simulated increases in the intensity of the l owest frequency foods are shown to be particularly severe, suggesting that greenhouse-related climatic change may be most detectable through an increase in extreme food events rather than changes in long-term m eans. Similar results are evident when changes in the frequency and in tensity of prolonged rainfall events, measured over a period of five c onsecutive days, are analysed. All results are qualitatively similar t o those for the Australian region, except that the model's sensitivity to sharp changes in topography over southern Africa is highlighted.