Parameterization of Subgrid-Scale Fluxes in Mesoscale Meteorological Models

Abstract : The problem of subgrid turbulent flux parameterization for mesoscale meteorological models is considered. A particular scheme is recommended, based on a quasi-equilibrium approximation to the A.R.A.P. second-order closure model of turbulent transport in the atmosphere. Tests of this scheme, as compared with results from a full second-order closure, high resolution, 1-D model, indicate reasonable results when the model grid resolution is adequate to include a few points in the unstable boundary layer. The scheme incorporates parameterization as an integral part of the quasi-equilibrium, and suggests that intermittency is a fundamental feature of cumulus cloud environment. Further testing of the scheme is recommended, particularly for the cumulus parameterization. Keywords: Turbulent flux parameterization; Convective scalar diffusion; Free convection surface layer; Cumulus parameterization; Planetary boundary layer.