UC Davis

The radiative effects of Saharan mineral dust (SMD) aerosols on the structure, location and energetics of the African easterly jet–African easterly wave (AEJ-AEW) system are examined for July–September 2006. Experiments are conducted with and without SMD using the Weather Research and Forecasting (WRF) model, which is radiatively coupled to an interactive dust model. The SMD-modified heating field shifts the AEJ northward, upward and westward, and enhances its zonal asymmetry. These SMD-induced changes to the AEJ are manifest in the AEWs: the northern and southern tracks of the AEWs shift northward (like the AEJ); and the zonal-scale of the AEWs expands and their westward propagation increases. The SMD also strengthens the energetics of the AEJ-AEW system. The domain and temporally averaged baroclinic energy conversion, which is an order of magnitude larger than the barotropic conversion, increases by a factor of 2.5. The eddy kinetic energy and generation of available potential energy increase by factors of 1.5 and 2.7, respectively. The implications of an SMD-modified AEJ-AEW system for West African precipitation and tropical cyclogenesis in the eastern Atlantic Ocean are discussed.