A Climatonomic Description of the Surface Energy Balance in the Central Sahel. Part II: The Evapoclimatonomy Submodel

Abstract

In Part I of this article we presented a study of the shortwave radiation budget in the West African Sahel, using Lettau's climatonomy model. In Part II, we apply the second of Lettau's submodels, evapoclimatonomy, to quantifying the surface water balance in the Sahel near Niamey, Niger. The model uses monthly means of ground-absorbed solar radiation and precipitation as input, and it predicts evapotranspiration, runoff, and exchangeable soil moisture. Sensitivity studies show that the model results are most affected by precipitation and by two prescribed model parameters, an evaporivity (e*) and a residence time (t*). Model results suggest that in the Sahel, rainfall and not insolation is the limiting factor in determining water balance characteristics.