Relationships Between Tropical Oceanic Convective Structure and Near-storm Environments Through the Lens of Idealized Numerical Modeling

Tropical oceanic convection plays a key role in driving regional and global weather and climate. Prediction challenges remain, however, partly attributed to a lack of understanding of tropical convective structure and how it evolves in response to nearby moisture and wind conditions. Therefore, analysis of three-dimensional convective structure—ranging from mesoscale convective systems down to cellular convection—and near-storm environments is essential to improve convective process-level knowledge and, subsequently, weather and climate modeling. This need motivated the NASA Convective Processes Experiment (CPEX) field campaign series in the tropical Atlantic, which provides coincident airborne radar, Doppler wind lidar, and dropsonde measurements that are used to investigate these near-storm relationships and serve as benchmark databases for numerical model simulations.

In this study, CPEX observations are used in combination with idealized tropical oceanic convection simulations from the Cloud Model 1 (CM1) numerical model to investigate relationships between tropical oceanic convection and relative humidity and vertical wind shear over different vertical layers. Simulations are initialized by and nudged to moist tropical soundings informed by typical near-storm environmental moisture and wind profiles from the CPEX campaign series to analyze their influence on domain-wide convective organization and vertical structure. In particular, sensitivity tests varying moisture in the planetary boundary layer and below and above the freezing level will be discussed, as well as sensitivity tests involving the introduction of a mid-level easterly jet and varying deep layer wind shear. Results from these idealized numerical model simulations in the context of observations will be presented, including comparisons with similar analysis of tropical oceanic convective structure from the CPEX field campaign series.