This paper reviews West African land/atmosphere interaction studies during the past decade. Four issues are addressed in this paper: land data development, land/atmosphere interactions at seasonal-interannual scales, mesoscale studies, and the future prospective. The development of the AMMA Land Surface Model Intercomparison Project has produced a valuable analysis of the land surface state and fluxes which have been applied in a number of large-scale African regional studies. In seasonal-interannual West African climate studies, the latest evidence from satellite data analyses and modeling studies confirm that the West African region has a climate which is particularly sensitive to land surface processes and there is a strong coupling between land surface processes and regional climate at intraseasonal/seasonal scales. These studies indicate that proper land surface process representations and land status initialization would substantially improve predictions and enhance the predictability of West African climate. Mesoscale studies have revealed new understanding of how soil moisture heterogeneity influences the development of convective storms over the course of the diurnal cycle. Finally, several important issues regarding the future prospective are briefly addressed. 1. Introduction West Africa is a diverse climatic region that includes a semiarid tropical zone in its northern section and a humid tropical climate zone in its southern section. Today, it is a bioclimatic zone of predominantly annual grasses with shrubs and trees, receiving a mean annual rainfall of between 150 and 2500？mm per year (Figure 1(a)). According to the United Nations’ definition [1], it includes 16 African countries and covers an area in excess of approximately 6？million？km2. Its northern boundary is along the southern margin of the Sahara Desert, with the Atlantic Ocean to its west and to its south. There is no consensus on its eastern boundary, which is commonly specified using a line running from Mount Cameroon to Lake Chad. The elevation of the vast majority of this land is less than 300 meters above sea level, though isolated points of higher elevation exist in several countries along the southern shore of the region. Figure 1: (a) Observed climate annual mean precipitation (mm？day ？1); (b) time series of June-July-August-September (JJAS) mean precipitation (mm？day ？1) averaged over 20°W to 20°E and 5°N to 20°N (the box outlined in (a)); (c) observed JJAS precipitation difference (mm？day ？1) between the 1980s and the 1950s; (d) observed JJAS precipitation difference
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