PNNL

Abstract

The Energy Exascale Earth System Model (E3SM) Land Model (ELM) is a state-of-the-art land surface model that simulates the intricate interactions between the terrestrial land surface and other components of the Earth system. Originating from the Community Land Model (CLM) version 4.5, ELM has been under active development, with added new features and functionality, including plant hydraulics, radiation-topography interaction, subsurface multiphase flow, and more explicit land use and management practices. This study integrates ELM with the Weather Research and Forecasting (WRF) Model through a modified Lightweight Infrastructure for Land Atmosphere Coupling (LILAC) framework, enabling affordable high-resolution simulations over a limited region by leveraging ELM’s innovative features alongside WRF’s diverse atmospheric parameterization options at regional scales. This framework includes a top-level driver for variable communication between WRF and ELM and Earth System Modeling Framework (ESMF) caps for WRF atmospheric component and ELM workflow control, encompassing initialization, execution, and finalization. Importantly, the core ELM structure is preserved, allowing future developments in ELM to transfer seamlessly to WRF-ELM. . To test the ability of the coupled model in capturing land-atmosphere interactions over regions with a variety of land uses and land covers, we conducted high-resolution (4 km) WRF-ELM ensemble simulations over the Great Lakes Region (GLR) in the summer of 2018 and systematically compared the results against observations, reanalysis data, and WRF-CTSM (WRF-coupled with the Community Terrestrial Systems Model). In general, the coupled model has effectively captured the spatial distribution of surface state variables and fluxes across the GLR, particularly over the natural vegetation areas. The evaluation results provide a baseline reference for further model improvements. Our work serves as an example to the model development community for expanding an advanced land surface model’s capability to represent fully-coupled land-atmosphere interactions at fine spatial scales. The development and release of WRF-ELM marks a significant advancement for the ELM user community, providing opportunities for fine-scale regional representation, parameter calibration in coupled mode, and examination of new schemes with atmospheric feedback.