OP-E2.5 Precipitation Downscaling

Poster Title	A new precipitation downscaling method for the topography-based subgrid structure in E3SM Model
Authors	Teklu Tesfa, Ruby Leung, Steve Ghan (Unlicensed)
First Author	Teklu Tesfa
Session Type	E3SM
Session ID	E2
Submission Type	Presentation
Group	Land
Experiment
Poster Link

Abstract

The effects of subgrid spatial heterogeneity of topography are not well represented in current Earth System Models (ESM). Recently, we developed a new representation of topography-based landunits within the hierarchical subgrid spatial structure of the Energy Exascale Earth System Model (E3SM) Land Model (ELM) to improve representation of land surface processes. This approach requires minimal increase in computational demand, while improving the ability to capture the spatial heterogeneity of atmospheric forcing and land cover influenced by topography. Because subgrid topography has important effects on atmospheric processes that control temperature, radiation, and precipitation, implementation of the new subgrid structure in E3SM necessitates the development of downscaling methods of atmospheric forcing from grid cell mean to the subgrid topography-based structures of the land surface model. This study specifically focusses on the development of a new topography-based precipitation downscaling method designed for the implementation of the new subgrid structure in E3SM. The method utilizes the Froude Number to capture the impact of topographic heterogeneity on orographic precipitation over topographically diverse regions. We present results evaluating the effectiveness of the new method as compared to other standard downscaling methods over the conterminous US domain.