Exploring Variability of the Level of Neutral Buoyancy and Level of Maximum Detrainment for Deep Convective Clouds

 
Poster PDF

Authors

Michael Jensen — Brookhaven National Laboratory
Die Wang — Brookhaven National Laboratory
Jennifer Anna Diorio — The Pennsylvania State University
Gina Jozef — University of Colorado, Boulder
Karen Lee Johnson — Brookhaven National Laboratory
Scott Giangrande — Brookhaven National Laboratory
Mariusz Starzec — University of North Dakota

Category

Convective clouds, including aerosol interactions

Description

Deep convective clouds are important drivers of large-scale atmospheric circulation representing the main vertical transport pathway through the depth of the tropopause for heat, momentum, water and chemical species. The strength and depth of this transport is impacted by the convective updraft size and strength driven by buoyancy and dynamical forcing and mixing of environmental air, i.e. entrainment. In this study, we use the difference between the level of neutral buoyancy (LNB; the theoretical height that a surface parcel raised above the level of free convection would reach with no mixing) and the level of maximum detrainment (LMD; height of maximum reflectivity in forward anvil cloud), as a proxy for the bulk convective entrainment rate (ER). Using the Active Remote Sensing of CLouds (ARSCL) value added product we identify deep convective clouds with a well observed forward anvil for ARM fixed-site deployments in the Tropical Western Pacific (Manus, Nauru, Darwin), and ARM Mobile Facility Deployments at: Niamey, Niger; Gan Island, Maldives; and Manacapuru, Brazil. For each identified cloud the LNB and LMD were determined along with several other convective indices. We investigate the relationships between these convective indices and the proxy entrainment finding that the CAPE and Level of Free Convection explain the greatest portion of the variance of any of the selected variables.