This award supports a three-year collaborative research project between Ms. Karyn Sawyer, with the University Corporation for Atmospheric Research (UCAR), Dr. Wassila Thiaw, with UCAR's African Desk at the National Center for Environmental Prediction (NCEP), and Dr. Saidou Sall, with the Laboratorie de Physique de l'Atmosphere of the Ecole Superieure Polytechnique at the University of Dakar in Senegal. They will study the interannual variability of African waves and influence on Sahel precipitation.
African waves are inherent components of the West Africa monsoon system. They start from the African interior, and as they multiply and move westward mesoscale convective systems (MCSs) often form and develop within the waves. These waves are most active during July and August. This is also the period of active convective rains in the Sahel. But little is known about the interannual variability of the waves or how they influence the interannual variability of rainfall in the Sahel. In order to determine the influence of the African waves on Sahel rainfall variability, the investigators will consider the relationship between the number of African waves and the amount of Sahel precipitation, the relationship between the number of African waves and the position and intensity of the Intertropical Convergence Zone (ITCZ), and whether the African waves and the position of the ITCZ modulate Sahel rainfall. They will use NCEP-UCAR data, satellite imagery, and field data obtained from observation studies. A convective index will be derived for each time step to determine the characteristics associated with the life cycle of the MCSs. Statistical analyses will then be performed to investigate the relationship between the number of African waves and Sahel precipitation. The results are expected to advance the current understanding of the West African monsoon system, especially the contribution of the interannual variability in the African waves to Sahel precipitation variability. It should advance our understanding of how large scale climate systems interact with local scale phenomena. It combines the international project expertise of Ms. Sawyer, with Dr. Thiaw's expertise in estimating rainfall and climate prediction in West Africa, and Dr. Sall's knowledge about convective systems.
