Dataset associated with "Controls on the Development and Circulation of Terminal versus Transient Congestus Clouds and Implications for Midlevel Aerosol Transport"

Cumulus congestus is the middle mode of tropical convection, with cloud tops typically around or exceeding the 0ºC freezing level (~5km AGL). While some congestus are terminal, meaning they are capped by the freezing level inversion, others are transient and may develop into deep convection. Although this distinction impacts convective transport into the mid-troposphere and the congestus-to-deep convection transition, little is understood about what determines whether a congestus overshoots the freezing level. We simulate a field of tropical congestus using high-resolution idealized model simulations, identify and track the updrafts, and composite congestus properties. Congestus updrafts are characterized by a similar overturning circulation between the updraft and its surrounding subsiding shell. However, transient congestus have stronger updrafts, and the downward branch of their corresponding circulations are found to be constrained by the freezing level inversion. The balance between buoyancy and perturbation pressure gradient accelerations is shown to determine the shape of the vertical velocity profile, though horizontal advection also impacts the magnitude of vertical velocity especially for mature transient congestus. Previous studies have focused on buoyancy as a control on congestus height, but we find that perturbation pressure gradient accelerations are equally important in allowing congestus to overshoot the freezing level. Finally, we explore how congestus updrafts influence their near environment: terminal congestus regenerate more aerosol through evaporation along their edges, while transient congestus create stronger detrainment layers of aerosol and water vapor in the midlevels due to regenerated aerosol being trapped above the freezing level stable layer.
These data represent the model namelist and source codes used to generate idealized large eddy simulations of congestus clouds using the Regional Atmospheric Modeling System (RAMS) version 6.3.02.
Department of Atmospheric Science
Rights Access
cumulus congestus
momentum budget
convective transport
numerical modeling
large eddy simulation
Associated Publications
Leung, G. R., and S. C. van den Heever, 2022: Controls on the Development and Circulation of Terminal versus Transient Congestus Clouds and Implications for Midlevel Aerosol Transport. J. Atmos. Sci., 79, 3083–3101,