Semiprognostic tests of cumulus parameterization schemes in the middle latitudes

Abstract

The vertical distributions of warming and drying are fairly well reproduced by the Arakawa-Schubert scheme; however, excessive amounts are predicted in most of the lower troposphere and insufficient drying is predicted just near the surface. This was ameliorated by incorporating moist convective-scale downdrafts into the parameterization. For the Kreitzberg-Perkey scheme, the most severe limitations were found to be a lack of dependence on large-scale destabilizing effects in the dynamic control and the assumption that clouds instantly decay and mix with their environment in the feedback. For the Kuo-type schemes, tests of its dynamic control demonstrated the need to include mesoscale moisture convergence in order to correctly predict the vertical integrated heating and drying rates, unless the resolved scale is fairly small and the moistening parameter is set to zero. Tests with the feedback - wherein the vertical distribution of heating and drying is dictated by the differences between cloud and environmental thermodynamic properties - revealed serious shortcomings. -from Authors