Hurricane Model Experiments with a New Cumulus Parameterization Scheme

Abstract

A cumulus parameterization scheme that utilizes a one-dimensional cloud model is tested in a revised, axisymmetric hurricane model. The details of how the parameterization scheme may he incorporated into a larger wale model are presented. With a mean tropical sounding, the cumulus parameterization scheme yields a vertical distribution of heating that is appropriate for tropical cyclone development. The structure of the model hurricane and the properties of the convective clouds at various stages of the model storm development are described. The vertical distribution of the cloud-scale heating and the vertical eddy fluxes of heat, moisture and momentum are given as a function of radius from the storm center during the mature stage. The vertical fluxes of heat and moisture cool and dry the lower troposphere while they warm and moisten the upper troposphere. The vertical transport of radial momentum by the cumulus convection is relatively unimportant, however, the transport of tangential momentum is significant in reducing the vertical shear of the tangential wind.