Tropical Waves Are Key Drivers of Extreme Precipitation Events in the Central Sahel

Peyrillé, Philippe ; Roehrig, Romain ; Sanogo, Sidiki

Année de publication
<p align=justify>Extreme precipitation events (EPE) are often associated with severe floods and significant damages in Central Sahel. To better understand their formation and improve their forecasts, we investigate the sub-seasonal drivers of EPEs. A composite analysis reveals that moist, cyclonic and upper-level divergence anomalies are found on average as a result of several tropical waves. The equatorial Rossby wave (ER) dominates at large scale providing a moist and convectively-active anomaly over the northern Sahel together with a smaller-scale African Easterly Wave (AEW). The Madden-Julian Oscillation provides upper-level divergence anomalies and a Kelvin wave increases convection during the EPE. Statistics show the prevalence of AEW and emphasize ER as a key driver of EPE. The co-occurrences of several tropical waves, especially those involving AEW, ER, and Kelvin waves, increase the probability of EPE. Monitoring these tropical waves combinations could improve EPEs forecasts.</p>
Texte intégral

puce  Accès à la notice sur le site du portail documentaire de Météo-France

  Liste complète des notices publiques