Vertical Wind Shear Influences on Tropical Oceanic Convection in Idealized Numerical Model Simulations

Deep tropical oceanic convection (TOC) is a prevailing component of the tropical atmosphere. Given its frequent occurrence, understanding environmental controls on collective spatial organization of TOC has implications for TOC impacts on global and regional weather and climate. Isolating the influence of known environmental factors, such as vertical wind shear and moisture, require idealized modeling grounded in reality. Informed by high-resolution near-storm environmental observations from the NASA Convective Processes Experiment (CPEX) airborne field campaign series in the tropical North Atlantic, Cloud Model 1 idealized simulations of TOC were executed to investigate how local wind shear and moisture separately influence collective TOC spatial organization. Using sensitivity simulations, each with a different combination of three unique deep layer wind shear and lower free tropospheric moisture profiles, deep layer shear was found to consistently promote collective TOC spatial organization. Notably, convective spatial organization was more dependent on deep layer shear in environments with moderate lower free tropospheric moisture (e.g., 60-76% relative humidity), wherein convection self-aggregated perpendicular to the shear vector. When lower free tropospheric moisture was high (e.g., 90% relative humidity), it was the dominant control of TOC spatial organization over deep layer shear. Extending impacts to the vertical, stronger deep layer shear and a drier lower free troposphere were both found to promote more bottom-heavy convection. Deep layer shear was also consistently linked to less intense convection, likely through updraft deflection from convective tilting that also increased convective system areas, further highlighting the three-dimensional influence of shear on TOC.