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Explore the benefits of watershed grid representation in the Energy Exascale Earth System Model (E3SM), addressing advantages, challenges, and future opportunities for realistic land surface modeling. Develop a mapping file for seamless atmospheric and land model interactions.
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Watershed Grid for the Energy Exascale Earth System Model (E3SM) Teklu K. Tesfa and Ruby Leung, Peter Thornton
Motivation: Why watershed grid? • Watershed grid representation offers distinct advantages • It follows the natural topographic divides and river network structure that governs hydrological processes • Simplifies representation of runoff schemes such as the TOPMODEL formulations Tesfa et al., 2014 a & b
Motivation: Why watershed grid? • Watershed grid representation offers distinct advantages • More realistic representation of land surface processes such as sediment, river transport, inundation and human impacts e.g. dams/reservoirs • Relaxed requirement for lateral water redistribution from neighboring watershed grids • Studies show clear scalability advantage compared to regular grid based land surface modeling Tesfa et al., 2014 a & b Mean Absolute Error
Motivation: Why watershed grid? • Watershed grid representation offers distinct advantages • Watershed grid offers an opportunity to developing a better topography-based subgrid structure • More realistic representation of topographic heterogeneity such as impacts of slope and aspect; • Option for configuring ELM-MOSART-WM on the same grid • also possibility for developing subgrid structures with hydrologic connectivity:
Watershed Grid Development: progress • Watershed Grid developed from high resolution elevation data • Stream network and other topographic attributes are developed from the same DEM
Watershed Grid Development: challenges • Delineation of watersheds located at the land-ocean interface (coastal area) require additional efforts beyond the normal watershed delineation process • Coastal outlet points identified over South American continent • The outlet points are used to delineate the coastal watersheds
Opportunities considered • Offline and online coupled simulations using the watershed grid • A mapping file is needed between the atmospheric grid and the watershed grid • Atmospheric model runs on grid-level only • Land model runs using watershed grid • Atmospheric fluxes are mapped onto the watershed grid • Land surfaces fluxes are mapped onto the atmospheric grid Atmospheric Grid Mapping to Watershed grid Mapping to Atmospheric grid Watershed grids
Discussion • The goal is to have a watershed grid-based configuration option in E3SM, with possibility to run ELM-MOSART-WM using watershed grid. For this purpose, a mapping file between atmospheric grid and watershed grid needs to be developed. • One way to implement the watershed grid configuration is to introduce a subroutine to facilitate the mapping of fluxes between the coupler and the land model component using a mapping file. • Is there other better approach to implementing the watershed-grid? • What is the implication of this to the computational demand and to the coupler?