Intercomparison of Multi-Day Simulations of Convection during TOGA COARE with Several Cloud-Resolving and Single-Column Models

The goal of the Global Energy and Water Experiment (GEWEX) Cloud System Study (GCSS) is to improve the parameterization of cloud-related processes in global climate models (GCMs) through an improved physical understanding of these processes. The main tool of GCSS is the cloud-resolving model (CRM), which is a numerical model that resolves cloud-scale (and mesoscale) circulations in either two or three spatial dimensions. In contrast, a GCM cannot resolve the individual convective cells or even the accompanying mesoscale circulations. Therefore, the collective effects of these sub-grid scale processes must be parameterized. A CRM is able to determine these collective effects directly, to the extent that its representation of gridscale dynamics and the parameterizations of its own subgrid processes are accurate. A general approach for using CRMs, in conjunction with single-column models (SCMs) and observations, to test and develop parameterizations for GCMs was described by Randall et al. (1996).