Properties of Tropical Cloud Ensembles Estimated Using a Cloud Model and an Observed Updraft Population

Abstract

A simple cloud model is developed which is designed for both diagnostic studies and mesoscale cumulus parameterization experiments. The cloud model is combined with an observed population of tropical convective updrafts and used to examine the vertical distributions of convective beating and moistening produced by tropical cloud ensembles. Although the cloud model ensembles are dominated by deep cumulonimbi, their vertical beating and moistening profiles differ significantly from those of individual clouds. These profiles and the total rainfall are sensitive to assumptions that affect the vertical mass flux distributions of the clouds. The ensemble heating and moistening profiles are in general agreement with large-scale budget analyses except for a tendency for the former to concentrate more of the heating above 600 mb. Modeled convective properties are found to be highly sensitive to assumptions concerning the convective environment immediately surrounding the updrafts and downdrafts. This has important implications for cumulus parameterization experiments, particularly in coarse-grid models.