An explicit approach to microphysics in MC2

An explicit microphysics scheme, including warm rain and ice-phase processes, 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 explicitly. The hydrometeor mass loading term is also included Far the single ice category, a generalized gamma size distribution is assumed and a new formulation by Meyers et al. (1992) is used to predict the ice concentration. A numerical simulation of the ERICA IOP2 cyclone shows that the scheme is efficient. Despite running at a relatively large time step, the scheme succeeded in capturing the deepening rates and the mesoscale features of the cyclone. The distribution of cloud and precipitation is in good agreement with satellite observations. Comparison with other implicit schemes available in MC2 show comparable performance in terms of deepening rate and precipitation rate. However, the explicit scheme generates mesoscale features in better agreement with observations.