Relating Convective Lifecycle to Near-Storm Environmental Parameters: Insights from Two CPEX-CV Cases

Convective systems associated with African Easterly Waves (AEWs) that propagate and intensify over the tropical east Atlantic may serve as precursors for tropical cyclones. Due to sparse data in the tropical east Atlantic, the interaction between near-storm environmental parameters with convective lifecycle and 3-D structure is not completely understood. Previous studies using satellite and reanalysis data emphasized column moisture influence on convective rainfall over tropical oceans with variability of environmental moisture at different pressure levels. Higher temporal and spatial resolution airborne data from NASA’s Convective Processes Experiment-Cabo Verde (CPEX-CV), operating from Sal Island during September 2022, is available from the Airborne Precipitation Radar (APR-3), Doppler Aerosols Wind Lidar (DAWN), High Altitude Microwave Sounding Radiometer (HAMSR), and dropsondes to measure near-storm environmental parameters near convective systems. Our approach to evaluating the relationship between convective lifecycle and environmental parameters consists of computing relative humidity (RH) and vertical wind shear over defined low-, mid-, and upper- levels with respect to proximity to growing, mature, and decaying convective systems obtained by the airborne radar from CPEX-CV.

Research Flight 7 (RF7), occurring on 16 September 2022, made multiple passes through a growing mesoscale convective system (MCS) along with nearby mature and decaying convective cells associated with a weak AEW. The convective cells were located to the west of the broad AEW center and on the moist side of a large-scale gradient with dry, dusty mid-level air to the northwest. Our research found that mid-level RH is greatest near convection for both the growing MCS and the decaying convective cell and drier toward the AEW center. Additionally, vertical wind shear is greatest near convection for both the growing MCS and the decaying convective cell, with higher vertical wind shear values associated with the growing MCS. We will present results from this flight in comparison with another CPEX-CV research flight with multiple passes through a convective system to discuss variability among cases.