An Approach for the Representation of Surface Heterogeneity in Land Surface Models. Part II: Validation and Sensitivity Experiments

Abstract

This paper discusses a series of sensitivity experiments aimed at testing the surface heterogeneity representation proposed in the companion paper by Giorgi. When driven by observed climatic forcings at three locations and run in point mode, the model shows good performance in reproducing observed surface fluxes. The temperature heterogeneity representation mostly affects the process of snow formation and, therefore, the winter and spring energy and water budgets. The soil water heterogeneity primarily influences the processes of soil water movement and runoff generation, thereby modifying the surface hydrologic budget. In addition, the heterogeneous model results compare reasonably well with aggregated results from point-mode experiments. Model sensitivity to the presence of impermeable surface fractional cover, fractional precipitation area, and a crude delayed runoff formulation is also discussed. As a next phase of model evaluation, it is planned to include this heterogeneity representation within a regional climate model and assess its effect on atmospheric circulations.