Vegetation-climate interaction and Sahel climate variability

The role a naturally varying vegetation in influencing the climate variability in the Sahel is investigated in a coupled atmosphere-land-vegetation model of intermediate complexity. The Sahel rainfall variability is initially forced by sea surface temperature (SST). Land-surface hydrology is found to increase this variability both on interannual and interdecadal time scales. Interactive vegetation enhances the interdecadal variation significantly, but can reduce year to year change due to a phase lag introduced by the relatively slow vegetation adjusting time. The results suggest the need for a good representation of vegetation dynamics in clmate models.