Characteristics of upper-level updrafts and downdrafts in the anvils of tropical deep convective clouds

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Abstract his study examines thermodynamic and microphysical relationships between in-cloud updrafts and downdrafts within tropical deep convective anvil clouds, using aircraft in situ measurements from the Aerosol, Cloud, Precipitation, and Radiation Interactions and Dynamics of Convective Cloud Systems–Cloud Processes of the Main Precipitation Systems in Brazil (ACRIDICON–CHUVA) field campaign. Our results extend current knowledge of in-cloud drafts to higher altitudes and add detail regarding their microphysical characteristics. Key findings include observational evidence of supersaturated downdrafts and higher cloud particle number concentrations in downdrafts than in updrafts within optically thick anvil clouds. Mean draft diameters exhibit a broadening trend with altitude, while mean air-mass fluxes decrease due to decreasing vertical velocity intensity and atmospheric density. Cloud water content is comparable in up- and downdrafts and increases with vertical velocity at all levels, without a clear trend with altitude. At upper levels (10–14 km), large negative vertical velocities are observed in supersaturated regions ; therefore, upper-level downdrafts do not appear to be driven by latent cooling. Optically thick cloud regions exhibit higher median RH and ice water content (IWC) compared with optically thin clouds, with downdrafts () showing higher median and IWC than updrafts. Particle size distributions are similar for up- and downdrafts of comparable strength. With altitude, maximum particle size increases, and the number concentration of larger particles () increases more strongly in stronger drafts than in weaker drafts. Stronger drafts also exhibit higher concentrations of particles smaller than 100 m at upper levels. Optically thick regions exhibit higher particle number concentrations across all sizes than optically thin regions. Notably, within the optically thick regions, downdrafts show higher particle number concentrations than updrafts for all sizes. Overall, the characteristics of updrafts and downdrafts in anvil clouds exhibit strong similarities, suggesting the influence of processes, such as updraft–downdraft mixing and inertia-driven downdrafts originating from older updraft cores, shaping microphysical and dynamical properties of anvil clouds.