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Charles Williams

Dr Charles Williams

Dr Charles Williams

Research Fellow

Grants awarded

Understanding rainfall variability and extreme events over southern Africa

Scheme: Dorothy Hodgkin Fellowship

Organisation: University of Reading

Dates: Jan 2007-Dec 2012

Value: £418,614.60

Summary: Recent climate-related disasters have demonstrated how extreme climate events can impact society. Rainfall extremes have been particularly devastating in recent years, as they cause both extreme drought and flooding and have caused massive personal, social and economic disaster. This is particularly true for vulnerable regions such as southern Africa. Here, environmental catastrophes are already causing widespread human suffering, and it is expected that they may become more frequent, more intense and possibly both with the effect of climate change. A good understanding of extreme rainfall is thus essential in order to provide accurate predictions of potential flooding. It is generally understood that various processes influence patterns of rainfall variability. Two important examples are the surface temperature of the sea in surrounding oceans, and the extent and type of land cover. However there are currently very few ground-based rainfall measurements over much of Africa, so other tools must therefore be used. Climate models are one such tool because they can simulate both present and future climate. My previous work was to use a climate model with a high resolution dataset in order to characterise the relationship between sea surface temperatures (SSTs) and rainfall over southern Africa. The other major process thought to be influential for extreme rainfall events is land use. My current project will therefore investigate the relationship between land cover and extreme rainfall and, thus, will tackle the question of whether local human changes to land use are the most important in influencing regional climate, or whether global atmospheric and oceanic processes dominate. The impacts of modifications to vegetation on climate will be studied, then existing data from previous studies will be incorporated into the model to investigate how land surface variations may impact extreme rainfall.

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