Change of rainfall distribution and circulation patterns over Southern Africa in summer

Abstract

Abstract The change of mean monthly rainfall, expressed as a percentage of mean annual rainfall, is described for the region south of 17°S during the course of summer. The areas with most rapidly increasing rainfall during monthly intervals are found to follow an almost circular path, starting out along the east coast and the adjacent interior in September and then being successively displaced to Zimbabwe, northern Botswana and northern South West Africa/Namibia, central and southern South West Africa/Namibia and ending in the central Cape Province in March. Several features of the atmospheric circulation and humidity are suggested and described as being partly responsible for the changing rainfall distribution.