Enhancement of Interdecadal Climate Variability in the Sahel by Vegetation Interaction

Abstract

The role of naturally varying vegetation in influencing the climate variability in the West African Sahel is explored in a coupled atmosphere-land-vegetation model. The Sahel rainfall variability is influenced by sea-surface temperature variations in the oceans. Land-surface feedback is found to increase this variability both on interannual and interdecadal time scales. Interactive vegetation enhances the interdecadal variation substantially but can reduce year-to-year variability because of a phase lag introduced by the relatively slow vegetation adjustment time. Variations in vegetation accompany the changes in rainfall, in particular the multidecadal drying trend from the 1950s to the 1980s.