Convective Organization in African Easterly Waves Observed During the NAMMA and CPEX‐CV Field Campaigns

Abstract Fundamental questions remain about where and when convection will occur within African easterly waves. In this study, we aim to better understand the dynamical processes that govern moist convective organization at the meso‐alpha scale in tropical easterly waves using NASA airborne field campaigns and satellite observations. We employ the SAMURAI 3D variational analysis technique in a vortex‐centric approach, integrating the fifth generation ECMWF (ERA5) reanalysis and research aircraft observations from 20 African easterly wave (AEW) cases sampled during the NASA African Monsoon Multidisciplinary Analyses (NAMMA) in 2006 and Convective Processes Experiment‐Cabo Verde (CPEX‐CV) in 2022. Infrared satellite imagery is used to obtain the frequency of occurrence within the wave of clear air, shallow/moderate convection, and deep convection relative to a potential vorticity (PV) centroid location. We identified four clusters of organized deep convection denoted as minimal deep, southern, southwestern, and widespread. Composites of the dynamical fields from the variational analyses show that high PV and relative humidity (RH) at mid‐levels were approximately co‐located with regions of low‐level convergence and more frequent deep convection, particularly for the southwestern and widespread clusters, which had the highest frequencies of deep convection. Waves with a higher frequency of deep convection are characterized by stronger PV and higher RH at mid‐levels compared to waves with a lower frequency of deep convection. The results suggest that improved understanding of the causal relationships between PV and RH and deep convection in easterly waves can lead to future forecast improvements of convective organization and tropical cyclogenesis.