The West African Sahel lies between the wet, humid equatorial zone of Africa to the south and the Sahara Desert to the north. This topography results in a strong north-south rainfall gradient and a climate with notoriously unreliable rainfall. In semiarid regions such as the Sahel, it has been shown that the influence of land cover and soil moisture are key components in the organization of surface fluxes and rainfall. The goal of this study is to further investigate this phenomenon and compare surface fluxes in dry versus wet regimes in the late summer of 1992.

A coupled land-atmosphere (cloud-resolving) model is used in conjunction with observed data from the Hydrological Atmospheric Pilot Experiment in the Sahel (HAPEX-Sahel) to simulate both wet and dry periods. Individual case studies are compared to available observations to evaluate the simulation of the diurnal cycles. Surface and subsurface soil moisture, surface fluxes, and rainfall are the key elements of the water balance examined in this study.