High-frequency precipitation changes in southeastern Africa due to anthropogenic forcing

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Abstract

This study evaluates differences in the precipitation regime over southeastern Africa simulated by two global climate models under present (1961–1990) and future (2071–2100) conditions as a result of greenhouse gases anthropogenic forcing. In particular, the characteristics of precipitation episodes with duration of some days are compared in both simulations. Precipitation in the models is previously compared to precipitation data obtained from the ERA-40 reanalyses and the Climate Prediction Centre (CPC), Climate Prediction Merged Analysis of Precipitation (CMAP). A precipitation episode is defined here as a period with a minimum number of consecutive days with daily precipitation above a threshold amount.

We consider a great range of episodes according to the preset threshold number of days (1–15 days) and daily precipitation amount (1–15 mm/day). For both climates, the number of episodes, their average duration and intensity are compared. The analysis is performed for both models. The results clearly show a tendency for a decrease in the number of episodes, in most of the region and for most episode categories, due to anthropogenic climate change. The duration of the episodes is reduced in the future climate for weak episode categories. For mild to intense episodes their duration is expected to increase over a small part of the region. The intensity of all episode categories is increased practically over the whole region. The spatial structure of these changes and its distribution according to the episode category are documented in this study. Copyright © 2007 Royal Meteorological Society

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