Projected and Observed Changes in East African Climate

Regional climate model simulations with 30-km resolution and 20 ensemble members capture the complex seasonal patterns of the East African rainfall climatology with greater accuracy than coupled GCM simulations.   One reason for the improved accuracy of the regional climate model is that the low-level circulation is more realistically simulated when the topography is better resolved, and it is also important to choose physical parameterizations that work well in the focus region.  Projections for the mid-21^st c., forced with GCM-generated sea surface temperatures and a business-as-usual atmospheric CO₂ scenario, indicate that the boreal spring long rains will be weakened in association with a strengthening of the Saharan and Arabian highs.  In contrast, the boreal fall short rains will be enhanced by positive trends in the easterly moisture transport due to increases in SSTs in the western Indian Ocean.

Reanalyses and precipitation observations are analyzed to understand if these processes are currently developing and contributing to the observed changes in the East African climate.