Assessing Moisture-Shear-Convection Relationships with CPEX-CV Airborne Observations and Reanalysis

Prior studies have linked increased environmental moisture to larger tropical oceanic mesoscale convective systems (MCSs) and higher rainfall rates, with conditional dependence on vertical wind shear and mixed results across studies. A challenge in comparing these observations across studies and regions is the use of different datasets (i.e., satellite, reanalysis, and models), with limited in situ observations over tropical oceans, and differing definitions of MCSs, moisture, and wind shear. To address data sparsity in the East Atlantic, NASA’s Convective Processes Experiment-Cabo Verde (CPEX-CV) conducted multiple Research flights (RFs) in 2022 using modern remote sensing and dropsonde instrumentation to sample a variety of oceanic MCSs and their environments. This study uses high-resolution CPEX-CV airborne observations to examine the interaction between near-storm moisture, vertical shear, and oceanic MCS characteristics in the East Atlantic, and evaluates the sensitivity of these relationships to dataset. Using an MCS tracker with geostationary satellite data as a storm-relative framework, we compared moisture-shear-convection relationships between remote sensors, dropsondes, and reanalysis for RFs 7 and 11. Most datasets showed a long-lived MCS growing in a moister mid-level and lower deep-layer shear environment than a short-lived, less intense storm. However, moisture-convection relationships were less clear when using remote sensor data, owing to sampling biases that affected conclusions about the temporal evolution of both cases, as well as challenges in reanalysis representing observed convection. These findings suggest that using different datasets can yield different conclusions about MCS-environment relationships, with implications for tropical regions with limited data availability.