Moment-Conserving Techniques for Warm Cloud Microphysical Computation. Part II. Model Testing and Results

Abstract

A model of an ascending parcel of air is used to evaluate and demonstrate the accuracy and utility of moment-conserving numerical techniques in cloud microphysical simulations. The sensitivity of the results to parameters of the computer code which might affect accuracy is evaluated. Discrepancies in the evolution of radar reflectivity are found to be satisfactorily small since the vertical displacement of equivalent radar reflectivities is shown to be within typical cloud model grid spacings. The collection calculation results are compared to a known solution and the condensation algorithm is tested by a comparison with a Lagrangian simulation. Simulations employing a maritime and two continental CCN distributions illuminate various features of the techniques employed. One of the continental cases is used to show the sensitivity of the evolution of large drops to the values of linear collision efficiency.