Recherche de structures spatio-temporelles en climatologie : l'exemple de la variabilité pluviométrique en Afrique orientale

Abstract. — Research of space-time structures in climatology. The example of rainfall variability in Eastern Africa. — Using monthly data from 79 stations between Eritrea and Mozambique, the space-time distribution of rainfall is studied for the 1953-1985 period. This part of Africa exhibits a large variety in the seasonal distribution of rainfall, ranging from double-peak equatorial regimes to single-peak tropical regimes. Several original patterns, particularly along the east coasts of Kenya and Madagascar, and over the Ethiopian Highlands, are also noticed. Thus, on the basis of interannual variability, this area clearly stands out as a distinct region, with its own unity. Maximum spatial coherence is experienced from October to December. Correlations between the rainfall signals associated to this region, and various climatic fields and indices, reveal that this spatial coherence of Eastern Africa is chiefly determined by large-scale climatic features of the equatorial Indian and Pacific oceans.