Informal Seminar: The Influence of Convectively Coupled Kelvin Waves on African Easterly Waves and Tropical Cyclogenesis

Recent research has illuminated a distinct relationship between convectively coupled Kelvin waves (CCKWs), African easterly waves (AEWs), and tropical cyclone (TC) formation. In this talk, I leverage a 39-year database of AEWs and TCs to investigate the cause and implications of these wave interactions. A composite analysis of ERA5 reanalysis and GridSat-B1 satellite data demonstrates that CCKWs directly influence characteristics of AEWs, such as their relative vorticity, humidity, and propagation speed. Furthermore, it is shown that AEW-CCKW interactions are exceedingly common in the Atlantic basin, with up to 76% of AEWs passing at least one CCKW in their lifetimes. Using these data, I will argue that CCKWs directly modulate TC genesis processes by enhancing convective aggregation and preconditioning their surrounding environment. I will also present preliminary results from ongoing experiments to dampen and amplify CCKWs in simulations of these wave interactions using NCAR’s Model for Prediction Across Scales (MPAS-A). These simulations are initialized using ECMWF’s Integrated Forecasting System (IFS), and results are compared to corresponding IFS forecast output.