Evaluating Environmental Moisture Relative to Tropical Deep Convective Growth Using CPEX-CV Airborne and Satellite Observations

Mesoscale convective systems (MCSs) associated with African easterly waves (AEWs) that propagate and intensify over the tropical East Atlantic may serve as precursors for tropical cyclones. Previous studies utilizing satellite- and reanalysis-based data emphasized that deep convective growth over tropical oceans favors moister environments, particularly near the AEW trough. Unknowns remain in the relationship between near-storm environmental parameters and convective lifecycle over the tropical East Atlantic. To address these knowledge gaps, NASA Convective Processes Experiment—Cabo Verde (CPEX-CV), based out of Sal Island in September 2022, deployed an airborne precipitation radar, a Doppler wind lidar, a microwave sounding radiometer, and dropsondes in this region. This study assessed the relationship between moisture and deep convection growth and sustainability using a combination of this unique airborne data set and satellite-derived products. More specifically, layer-averaged relative humidity was analyzed for a growing deep convection system sampled with multiple passes during Research Flight 7. These aircraft observations, supplemented with a geostationary satellite-based MCS tracker and reanalysis data, showed mid-tropospheric moistening facilitating continued growth and maintenance of the convective system during and after the flight in association with an AEW. In comparison, Research Flight 11 sampled a convective system in a drier environment closer to the West African coastline that dissipated after the flight, underscoring the importance of mid-tropospheric moisture for sustaining convective growth.