AN EXPLICIT APPROACH TO MICROPHYSICS IN MC2

An explicit microphysics scheme, including warm rain and ice-phase pro cesses, has been incorporated into the Canadian Mesoscale Compressible Community Model (MC2). Three equations for cloud water mixing ratio, rain wafer mixing ratio, and ice or snow mixing ratio are solved expli citly. The hydrometeor mass loading term is also included Far the sing le ice category, a generalized gamma size distribution is assumed and a new formulation by Meyers et al. (1992) is used to predict the ice c oncentration. A numerical simulation of the ERICA IOP2 cyclone shows t hat the scheme is efficient. Despite running at a relatively large tim e step, the scheme succeeded in capturing the deepening rates and the mesoscale features of the cyclone. The distribution of cloud and preci pitation is in good agreement with satellite observations. Comparison with other implicit schemes available in MC2 show comparable performan ce in terms of deepening rate and precipitation rate. However, the exp licit scheme generates mesoscale features in better agreement with obs ervations.