The Influence of Land Surface Properties on Sahel Climate. Part II. Afforestation

Abstract

A numerical experiment was performed to explore the nature of and mechanisms for the effect of large-scale afforestation in the sub-Saharan area on the climate. This sensitivity study, which consists of several short-term integrations of a climate model, suggests that afforestation would enhance the rainfall in the region and would have the largest impact during dry years. While the rainfall increased in the afforestation area, it decreased to the south of that region. It was found that this land surface change altered the surface energy balance and induced a circulation change that led to a change in rainfall. The influences of different vegetation species and the extent of the afforestation area on the rainfall were tested and are discussed. Reducing the afforestation area by about 50% still resulted in a positive simulated rainfall anomaly. A detailed analysis of the surface energy balance is presented. A comparison between the effects of afforestation and desertification is also made.