Model Simulation of the Influence of Global SST Anomalies on Sahel Rainfall

Abstract

A general circulation model sensitivity study was carried out to investigate the influence of global sea surface temperature (SST) on Sahel rainfall. This study was inspired by the impressive model simulations of Sahel rainfall reported by Folland et al. and Rowell et al. The model was integrated from June through September with three different atmospheric initial conditions and four years (1950, 1958, 1983, and 1984) of SST. In three out of four cases (1950, 1983, 1984), the area-averaged simulated rainfall anomaly was consistent with the observations. However, the model’s internal variability was rather large. The simulated anomalies had relatively larger sensitivity to the initial conditions in this study than those in a desertification study performed previously by the authors. This model failed to simulate the rainfall anomaly for 1958. Additional model experiments are needed to establish the role of SST variation in determining the Sahel rainfall variation.