Exploring New Topography-based Subgrid Architecture in Land Surface Modeling

Monday, 15 December 2014
Teklu K Tesfa, Pacific Northwest National Laboratory, Richland, WA, United States, L. Ruby Leung, PNNL / Climate Physics, Richland, WA, United States, Hong-Yi Li, Pac NW National Lab, Richland, WA, United States and Maoyi Huang, Pacific NW Nat'l Lab-Atmos Sci, Richland, WA, United States
Topography exerts a major control on land surface processes through its influence on atmospheric forcing, soil and vegetation properties, network topology and drainage area. Land surface modeling using subbasins instead of rectangular grids as computational units has been demonstrated to improve scalability of simulated runoff and streamflow processes. A new land surface spatial structure is being developed to further divide subbasins based on elevation, topographic slope and aspect classes to take advantage of the emergent patterns and scaling properties of atmospheric, hydrologic, and vegetation processes in land surface models. The topography-based spatial structure is being applied in the Community Land Model (CLM4.5) to represent spatial heterogeneity influenced by topography, soil, and vegetation. In this study, different methods to represent subgrid land surface heterogeneity are explored. CLM simulations using the new spatial structure will be configured and compared against CLM simulations using the standard grid-based spatial structure over topographically and climatically contrasting regions of the United States to evaluate the implications of the new spatial structure in land surface modeling.