Exploring the Influence of Equatorial Waves on a Record-Breaking Extreme Precipitation Event in Central Sahel: Insights From Convection Permitting Simulations
Étude de l'influence des ondes équatoriales sur un épisode de précipitations extrêmes record dans le centre du Sahel : enseignements tirés de simulations à résolution permettant la convection
Diakhaté, Moussa ; Peyrillé, Philippe ; Chaboureau, Jean-Pierre ; Beucher, Florent ; Couvreux, Fleur
Année de publication
2026
The floods of 01 September 2009 in Ouagadougou, Burkina Faso, were among the most severe in the Central Sahel's history, highlighting the region's persistent flood risk. This extreme precipitation event (EPE) was influenced by various atmospheric drivers, including Convectively Coupled Equatorial Waves (CCEWs). This study uses the Meso-NH numerical model to assess the individual impacts of CCEWs on the 2009 EPE. Results indicate that Tropical Disturbances (TDs) and Equatorial Rossby waves (ERs) significantly affect the system's propagation and intensity, with TD removal causing a northward shift and ER removal reducing precipitation due to upstream drying. Removing both TDs and ERs eliminates the EPE entirely in Ouagadougou, while other waves have minimal impact. These findings emphasize the crucial role of TD and ER interactions in triggering EPEs in the Central Sahel and highlight the importance of accurately representing these waves in forecasting models.</div>
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