RAINFALL VARIABILITY IN SUBEQUATORIAL AMERICA AND AFRICA AND RELATIONSHIPS WITH THE MAIN SEA-SURFACE TEMPERATURE MODES (1951-1990)

The rainfall variability of subequatorial South America and Africa is poorly documented owing to the scarcity of data. We present a new land -only data set of monthly precipitation from 1951 to 1990, focusing on subequatorial South America and Africa, which improves the knowledge of rainfall variability and allows comparisons with GCM outputs. The r esults of multivariate analyses are compared with those performed on t he best actual global rainfall data set developed by Mike Hulme. The m ain modes of bimonthly rainfall variability are not located in the maj or rain-forest basins of Zaire and Amazonia, but rather on the tropica l margins, such as Venezuela or Sudan, and near-coastal equatorial are as, such as Guyana, Nordeste, Guinea, and Gabon. A regionalization int o 13 homogeneous areas selected from the multivariate analyses is prop osed. The statistical links between the rainfall variability and the f our main sea-surface temperature modes indicate a strong influence of the El Nino-Southern Oscillation (ENSO) phenomenon upon South America (less/more rainfall during an El Nino/La Nina event) and a weaker impa ct, modulated by the Atlantic thermal state, upon Africa. The impact o f ENSO events seems stronger since 1965 than before.