Improving the Representation of Subgrid Topographic Effects in the Energy Exascale Earth System Model

Monday, December 10, 2018 - 09:30
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Topography has major control on land surface processes; however, the effects of its subgrid spatial heterogeneity are not well represented in current Earth System Models (ESMs). Recently, we developed topography-based landunits within a hierarchical subgrid spatial structure to improve representation of land surface processes in the Energy Exascale Earth System Model (E3SM) with a minimal increase in computational demand, while improving the ability to capture the spatial heterogeneity of atmospheric forcing and land cover influenced by topography. Recognizing that subgrid topography also has important effects on atmospheric processes that control temperature, radiation, and precipitation, methods have been developed to downscale grid cell mean atmospheric forcings to the subgrid topography-based landunits. This study focuses on evaluation of the impacts of the new spatial structures on modeling land surface processes. Results using E3SM land simulations with and without subgrid topography and driven by grid cell mean atmospheric forcing will be compared to isolate the impacts of the subgrid topography on the simulated land surface states and fluxes. Furthermore, the impacts of the subgrid topographic structure combined with spatial downscaling of the atmospheric forcings on land surface modeling will be evaluated by comparing the results with observations and simulations forced by the grid cell mean atmospheric forcing in topographically diverse regions such as the western U.S.

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