PARAMETERIZATION OF SUBGRID DEEP CONVECTIVE CLOUD AT GRAY-ZONE RESOLUTIONS:PRELIMINA RY RESULTS|

When the horizontal grid size of a numerical weather prediction(NWP)model is between a few hundred meters and~10 km,referred to as the gray zone,updrafts in convective clouds cannot be fully resolved explicitly and the use of a subgrid convective cloud parameterization scheme is still necessary.Since some critical assumptions in the mass-flux formulation of conventional subgrid convective cloud parameterization become invalid for gray-zone resolutions,it is required for a generalized parameterization to be developed to properly describe subgrid convective clouds.To meet this requirement,a new subgrid convective cloud parameterization scheme that is based on the mass-flux formulation and suitable for gray-zone resolutions has been proposed and preliminarily tested in the Weather Research and Forecasting(WRF)model.This new scheme is automatically adaptive to variation in grid size(i.e.,scale-aware),and accounts for microphysical processes consistently with grid-resolved clouds.Numerical experiment of an idealized tropical cyclone shows that this new scheme has a substantial impact on the tropical cyclone’s intensity and precipitation distribution due to the effect of subgrid clouds on the total diabatic heating.