The structure and possible forcing mechanisms of the 1991-1992 drought in Southern Africa

Abstract

A diagnostic model is used to investigate the underlying atmospheric processes that gave rise to the 1991-1992 drought over Southern Africa. The first indicator of the impending drought was a rise of more than 1 °C in the sea surface temperatures of the tropical part of the Southern Indian Ocean in the winter of 1991. This may have been instrumented in causing an anomaly in the mean Walker circulation to develop, through which the inflow of warm, moist air from the Mozambique Channel to the eastern escarpment of Southern Africa was inhibited, with a concurrent reduction in rainfall. It is concluded that the pattern and cycles of summer rainfall over Southern Africa are now sufficiently well understood to venture tentative predictions, but that increased co-operation between the meteorological bodies of Southern Africa will be required to achieve this.