Effects of downdrafts and mesoscale convective organization on the heat and moisture budgets of tropical cloud clusters. Part I: a diagnostic cumulus ensemble model

Abstract

The model adopts the spectral representation of a cumulus ensemble and includes the vertical momentum budgets for both convective-scale updrafts and downdrafts. The downdrafts are initiated and maintained by the loading and evaporation cooling effects of rainwater which is generated in the updrafts tilting from the vertical. A theory for determining the updraft tilting angle based on the stability analysis of the rainwater budget equation is presented. We find a remarkable correlation between the diagnosed updraft tilting angle and the degree of mesoscale convective organization observed by radar. -from Author