The Impact of Kelvin Waves during dry and wet African rainfall years

This study highlights the influence of convectively coupled Kelvin wave (KW) activity on deep convection and African easterly waves (AEWs) over North Africa during dry and wet boreal summer rainfall years. Composite analysis based on 25 years of rainfall, satellite observed cold cloud temperature, and reanalysis data sets show that KWs are more frequent and stronger in dry Central African years compared with wet years. Deep convection associated with KWs is slightly more amplified in dry years compared with wet years. Further, KW passage over North Africa strengthens the lower level zonal flow and deepens zonal moisture flux in dry years compared with wet years. Results also show that enhanced KW convection are in phase with above average AEW variance in dry years. However, enhanced KW convection is out-of-phase with average AEW activity in wet years. In general, evidence in this study suggests that KW passage over Africa enhances convective activity and more strongly modulate the monsoon flow and moisture flux during the dry years than wet years.Keywords: Kelvin waves; African easterly waves; African summer monsoon.