While flooding is a complex process involving both meteorological systems and surface conditions, most high-impact events are characterized by high rainfall totals. This study focuses on understanding storm systems that deliver high rainfall amounts over the West African Sahel, a relatively remote region known to be particularly vulnerable to flooding due to the frequent occurrence of intense rainfall and relatively low adaptive capacity. The overarching goal is to advance our physical understanding of the development of extreme rainfall-producing systems over the West African Sahel by investigating how environmental conditions contribute the development of such storms. Given the consequences of high-impact rainfall events for the livelihoods of West Africans, as well as the known role of these systems over the West African Sahel in Atlantic hurricanes, the knowledge gained from this study will be valuable for improving not only the prediction of high-impact rainfall events over the West African Sahel but also the weather forecast for our own national interests. The project also contributes to the education of the next generation of atmospheric scientists through involving and training a post-doctoral researcher and a graduate student as well as through a K-12 outreach program.

The specific objectives of this project are: (1) to understand the characteristics of precipitating systems that deliver high-impact rainfall amounts; and (2) to determine the set of environmental conditions that favor the development of these rainfall events. These objectives will be addressed by utilizing high-resolution satellite-derived rainfall products, state-of-the-art atmospheric reanalysis data, along with convection-permitting regional climate modeling. Satellite-derived rainfall estimates and ground-based observations will be used to identify and characterize high-impact rainfall events over the region, and these will be cross-referenced with ground-truth to identify events associated with reported flooding. Atmospheric reanalysis data and convection-permitting modeling will be used to identify the environmental conditions associated with intense storms, and to develop and test hypotheses regarding how they are related to deepen our understanding of the physical processes associated with the development of high-impact rainfall events.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.