Topographic Influence on the African Easterly Jet and African Easterly Wave Energetics

摘要

The topography of eastern Africa, namely, the Ethiopian Highlands and Marrah Mountains have been shown to play a key role in the genesis of African Easterly Waves (AEWs) through convective initiation in that region. Topographic influences on the African Easterly Jet, evolution and energetics of AEWs, and rainfall production across northern tropical Africa are examined here. The Weather Research and Forecasting model is employed to simulate the climate over a 60-day period for three years (2004, 2005, and 2006) for three cases with varying topography: realistic, half-height, and no topography. An energetics analysis for the resulting AEWs reveals that wave development by barotropic and baroclinic processes weakens when topography is flattened. These results show that topography in Africa plays a significant role in the wave development as they propagate westward, not only in their initiation over East Africa.