92nd American Meteorological Society Annual Meeting (January 22-26, 2012)

Thursday, 26 January 2012
Modeling the West African Monsoon and the Formation of African Easterly Waves
Hall E (New Orleans Convention Center )
Keri Younger, Embry Riddle Aeronautical University, Daytona Beach, FL; and E. D. Maloney and R. McCrary

The West African Monsoon brings seasonal rains to the Sahel region during the summer months of May to October. During this season, the African Easterly Jet (AEJ) is most strongly developed as a result of temperature and moisture gradients that span the region from the Gulf of Guinea to the Saharan desert. African easterly waves (AEWs) form in association with this jet. It is important to study AEW development and maintenance since AEWs propagate westward over the Atlantic and can foster development of hurricanes, as well as provide beneficial rainfall to west Africa during the summertime.

In this study, we use the regional Weather Research and Forecasting (WRF) Model version 3 over West Africa to study processes related to AEWs. We use ERA-Interim data from May 2006 to September 2006 to force the model at the boundary and validate the model runs. ECMWF AMMA reanalysis data were used to help validate the model runs. The conditions that cause variations in the strength of easterly waves within a season are discussed, as well as the influence these waves have on convection over West Africa. A series of model runs are conducted in which AEW information is filtered out of the ERA-Interim input data and boundary conditions to assess the impact on convection within the domain. Extension of the model domain to the west over the Atlantic is used to assess the implication of AEWs and their variability for tropical cyclone formation, including examination of how cyclogenesis statistics change when easterly waves are suppressed.

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