A GCM simulation study of the influence of Saharan evapotranspiration and surface-albedo anomalies on July circulation and rainfall

Abstract

In the first experiment a soil moisture anomaly was prescribed over North Africa, whereas in the second experiment a soil moisture plus surface albedo anomaly was prescribed. The third experiment had the soil moisture and surface albedo anomalies of the second experiment and was run with the second version of the model that included a recently modified parameterization of evaporation of falling rain. The first experiment shows that increased soil moisture and its dependent evapotranspiration produces a cooler and moister PBL over North Africa that is able to support enhanced moist convection and rainfall in Sahel and southern Sahara. The second experiment shows that the lower surface albedo yields even higher moist static energy in the PBL and further enhances the local moist convection and rainfall. The third experiment, produces hydrological cycle and accompanying rainfall anomalies that were quite similar to those of the second experiment specifically over the anomaly region; however, some differences between the second and third experiments were evident in distant regions. -from Authors