An atmospheric general circulation model with realistic land surface properties is used to investigate the climatic effect of doubling the extent of the earth's deserts. Control and anomaly integrations are performed for 10 years. In the anomaly case, deserts are expanded over North Africa, South Africa, Australia, south-central Asia, southwestern North America, and parts of South America.
In the anomaly case, the troposphere is cooler across most of the tropics and subtropics, including all areas where desertification occurs. Annual mean precipitation is reduced over North and South Africa, south-central Asia, and Australia. Precipitation over the eastern Sahel is reduced by over 60%, and droughts persist in all seasons over northern and southern Africa. Asia and Australia exhibit weaker monsoons, but there is little effect during winter. Precipitation increases over central Africa between the two desertified regions, over the ocean equatorward of Asia and Australia during those regions' monsoons, and over the desertified areas of western North America. Regions of increased rainfall occur over the ocean to the west of the desert regions of North and South America, Australia, and South Africa. Remote effects in the winter circulation include a pronounced trough over northern Europe, and increased geopotential heights over the southern oceans.
last update: 18 October 1994
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