Diagnostic modeling of vertical mass and heat fluxes in a tropical mesoscale convective system

Hemispheric and global numerical prognostic models for the foreseeable future will be of synoptic scale, requiring the parameterization of cumulus-scale and mesoscale tropical convection. Over the past decade a relatively simple steady-state model which diagnoses vertical mass and heat flux using radar-derived rainfall data has been developed by Houze and his associates. This model is applied by the present study to the GATE data set of 5 September 1974 which consists of a large grid of hourly radar observations of cloud height and reflectivity on the cumulus-scale and mesoscale in an active portion of an Atlantic easterly wave. Results show certain unrealistic features in the mesoscale portion of the model due apparently to the non-steady-state nature of cumulus ensemble anvils. Refinements are proposed to enable the model to realistically parameterize the mesoscale as well as the cumulus-scale components of tropical convection.