Lane Processes in a High Resolution Community Climate Model with Sub-Grid Scale Prameterizations

Many crucial processes occur on spatial scales too fine to be resolved by most current climate models. This grant addressed the need for and development of a high-resolution, fine-mesh global model for these processes. The proposed research represented a natural continuation of our current CHAMMP project, which concentrated on the development of earlier versions of a high-resolution land surface model coupled to various versions of the NCAR Community Climate Model (CCM). Sub-grid land processes are represented by a sub-mesh imposed on each atmospheric model grid square, rather than by the more common mosaic approach. The main objective of this grant was to upgrade the current fine-mesh model configuration to a 0.2o sub-mesh representation within a T-239L semi-Lagrangian version of the NCAR Community Climate Model (CCM). An initial test of the sub-mesh approach carried out simulations using the standard T-42 CCM but with a 0.75o (T-239L) sub-mesh representation of land processes and compared these with a complete T-239L simulation. Besides the land sub-mesh parameterizations, including rainfall, snow, radiation, near-surface variables, topographic effects, and land heterogeneity within the sub-mesh, it impremented other improvements within land surface parameterizations coupled to the CCM including treatments of near-surface boundary layers, soil layer structure, snow, and vegetation