Meridional interactions between rainfall and surface pressure

Abstract

WE have been investigating temporal variation in rainfall over a part of the Southern Hemisphere^1–4. In view of the current concern regarding food production and future climatic change (for example, a shift in the westerlies over the Northern Hemisphere) this area of research is of some importance. The recent drought and resulting famine in the Sahel^5–7 also shows that stresses in one hemisphere can be a burden on the food resources of the other. Until now, however, quantitative interactions between rainfall and the general circulation have not been given; here we show first, that there are structural relationships between annual rainfall over Southern Africa and the month to month variation in the mean latitude of the surface high pressure belt, L (ref. 8). The evidence adds credibility to findings related to the temporal variation in rainfall^2,4. Second, a means of forecasting annual rainfall totals is shown to be feasible. The method used in the analysis is neither geographically restricted, nor applicable to rainfall only.