The Saharan air layer and the fate of African easterly waves: NASA's AMMA field study of tropical cyclogenesis

National Aeronautics and Space Administration's (NASA) African Monsoon Multidisciplinary Analysis (AMMA), NAMMA, is a large international project that aims to improve the understanding of the West African monsoon, especially the African easterly waves (AEW). The project also aims to gain an improved understanding of the linkage between AEWs, the Saharan air layer (SAL), and tropical cyclogenesis. The seven AEWs sampled during the NAMMA field campaign has represented the best validation database ever obtained in the eastern North Atlantic, providing an opportunity to evaluate the latest remote sensing retrieval algorithms, and dynamics and microphysics parameterizations used in numerical models. It also gives an insight into how weak disturbances intensify and the role played by the structure and evolution of the SAL, with main development area for tropical cyclones in the Atlantic basin.