Investigating the role of lateral water transport in modulating land surface- atmosphere interactions in Southern Great Plains

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Description

The potential influence of the land surface on the atmosphere raises the question of whether a more detailed representation of land processes in numerical atmospheric models, for example, vegetation dynamics and terrestrial hydrology, would significantly affect model results, including surface fluxes, the structure of the boundary layer, and the initiation of convective clouds. The development of the integrated models have enabled scientific explorations of interactions and feedback mechanisms in the aquifer-soil-vegetation-atmosphere continuum using a holistic and physically based approach. Therefore, it is of great scientific interest to further develop the integrated models and benchmarks to achieve improved understanding of complex interactions in the fully coupled Earth system. The WRF model has been recently coupled with the National Center for Atmospheric Research Distributed Hydrologic Modeling System within the WRF-Hydro modeling system. In the standard version of WRF, runoff–infiltration partitioning is computed in a 1-D soil column without taking into account lateral water flow. In WRF-Hydro, the LSMs are enhanced with surface and subsurface flow routing, thus accounting for horizontal processes involved in runoff–infiltration partitioning for investigating the role of terrestrial hydrology on meso-scale land–atmosphere feedbacks. In this study, we configured WRF-hydro over a 100 km by 100 km domain centered around the Department of Energy Atmospheric Radiation Measurement (ARM) Facility’s Southern Great Plains (SGP) site, representative of a one-degree box used in current generation general circulation models. The surface and subsurface of the domain is discretized into 1 km for water and energy simulations in the vertical direction, while the lateral routing of overland and river flow is computed at 100 m resolution. Offline simulations of WRF-hydro are first conducted that are driven by meteorological forcing from the North American Land Data Assimilation System (NLDAS) for 2011 and 2012 to evaluate the effect of lateral water transport on surface energy and water budgets, benchmarked against observations from energy balance Bowen ratio (EBBR) and eddy correlation (ECOR) stations. Nested WRF simulations will be conducted to explore how different representations of hydrologic processes affect land-atmosphere interactions over SGP.