African Monsoon Systems: Basic Dynamics and Applications to Interannual and Decadal Prediction

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Research conducted in this project will address the basic dynamics of monsoon systems in Africa, focusing on West Africa, the Greater Horn of Africa (GHA), and the influence of "cold surges" moving across North Africa from the Mediterranean. In West Africa, the research will focus on the role of inertial instability in producing the often abrupt "jump" of the monsoon rains from the Guinea coast to the Sahel. In the GHA, the focus is on understanding the relationship between rainfall distribution and Somali jet, a low-level air current which forms in two distinct stages with are associated with the onset of monsoon rains in their respective subregions. The cold surges are important for rains in the Sahel, as they appear to be linked to the occurrence of break periods during the monsoon season when the rains are suppressed. Much of the work is carried out with a regional climate system model, which is capable of representing the weather and climate of the region, the upper layer of the adjacent oceans, and the land surface and its vegetation. The research seeks to identify the relevant physical mechanisms in present-day climate, and additional experiments will explore the possible effects of anthropogenic global warming on the African monsoon systems.The broader impacts of the work lie in the potential for a better understanding of the dynamics of the African monsoon systems to lead to skill in predicting monsoon variations, and to anticipate the effects of global warming. The PI notes that the populations of the regions considered in this study are extremely vulnerable to climate variability and change, for reasons including food and water security, health risks, and political stability. The work would also support a graduate student, thereby helping to develop the scientific workforce of the future.