COMPARISON OF CLOUD MICROPHYSICS PARAMETERIZATIONS FOR SIMULATION OF MESOSCALE CLOUDS AND PRECIPITATION

Cloud physics parameterizations are comprehensively reviewed in order to examine their theoretical bases and to evaluate their applicability to mesoscale modeling. The constant distribution functions of hydrometeors assumed in previous work are found to be unrealistic. To circumvent this problem, new parameterizations are developed for mixing ratios of water vapor, cloud water, rain water, cloud ice, graupel and snowflakes. Equations are derived from theoretical considerations and multiple regression applied to results of simulations with a cloud model that incorporates sophisticated treatments of microphysics and dynamics. In a Lagrangian air parcel model under variable atmospheric conditions, the new parameterizations give consistent results and are computationally more efficient than previously available parameterizations.