A CONVECTIVE CLOUD MODEL FOR USE IN A CUMULUS PARAMETERIZATION SCHEME

A quasi-one-dimensional steady-state cloud model that is based on inte grating the two-dimensional equation for the azimuthal vorticity over the cloud radius is described. The equations are reduced to one dimens ion in the vertical direction by assuming that the streamfunction is o scillatory and a function of r only allowing this model to incorporate the nonhydrostatic pressure gradient force. It also includes an empir ical buoyancy correction to account for vertical wind shear; the corre ction is based on application of the Klemp-Wilhelmson convective cloud model to a variety of buoyancy and wind-shear environments. In additi on, the model includes consideration of rainwater, freezing of condens ate, and a moist penetrative downdraft. The downdraft includes conside ration of the nonhydrostatic pressure gradient, rainwater loading, and buoyancy; below cloud base, it is unsaturated. The results from the m odel for cases with and without vertical wind shear are compared to th e Schlesinger three-dimensional cloud model results for the same envir onmental conditions. The amount and vertical variation of the vertical mass flux, heat flux, and water vapor flux calculated by the quasi-on e-dimensional model are comparable to the same produced by the Schlesi nger model. Finally, implications of these results in regard to using this model in cumulus parameterization are given.