Journal Article

E3SM‐Arctic: Regionally Refined Coupled Model for Advanced Understanding of Arctic Systems Interactions

Osinski, Robert, Wu, Mingxuan, Baxter, Ian, Rasch, Philip J., Zhang, Yu, Wolfe, Jonathan D., Zhang, Xiangdong, Garuba, Oluwayemi A., Weijer, Wilbert, Zhang, Jing, Comeau, Darin, Lin, Wuyin, Maslowski, Wieslaw, Lee, Younjoo J., Huo, Yiling, Craig, Anthony P., Asay‐Davis, Xylar, Roberts, Andrew F., Zhang, Shixuan, Wang, Hailong, Fu, Qiang, Roesler, Erika, Ma, Weiming, Hillman, Benjamin R., Veneziani, Milena, Seefeldt, Mark W., Sweeney, Aodhan

2025

Overview

Earth system models are essential tools for climate projections, but coarse resolutions limit regional accuracy, especially in the Arctic. Regionally refined meshes (RRMs) enhance resolution in key areas while maintaining computational efficiency. This paper provides an overview of the United States (U.S.) Department of Energy's (DOE's) Energy Exascale Earth System Model version 2.1 with an Arctic RRM, hereafter referred to as E3SMv2.1‐Arctic, for the atmosphere (25 km), land (25 km), and ocean/ice (10 km) components. We evaluate the atmospheric component and its interactions with land, ocean, and cryosphere by comparing the RRM (E3SM2.1‐Arctic) historical simulations (1950–2014) with the uniform low‐resolution (LR) counterpart, reanalysis products, and observational data sets. The RRM generally reduces biases in the LR model, improving simulations of Arctic large‐scale mean fields, such as precipitation, atmospheric circulation, clouds, atmospheric river frequency, and sea ice thickness. However, it introduces a seasonally dependent surface air temperature bias, reducing the LR cold bias in summer but enhancing the LR warm bias in winter, which contributes to the underestimated winter sea ice area and volume. Radiative feedback analysis shows similar climate feedback strengths in both model configurations, with the RRM exhibiting a more positive surface albedo feedback and contributing to a stronger surface warming than LR. These findings underscore the importance of high‐resolution modeling for advancing our understanding of Arctic climate changes and their broader global impacts, although some persistent biases appear to be independent of model resolution at 10–100 km scales. Plain Language Summary Earth system models (ESMs) are essential tools for understanding the climate system and projecting future changes, but standard coarse model resolutions often fail to realistically represent regional processes and topography, particularly in the polar regions, while uniform high‐resolution grids are too computationally expensive. To address this, regionally refined meshes (RRMs) have been developed within ESMs to provide high‐resolution simulations in target areas, improving the accuracy of regional climate simulations while maintaining computational efficiency. This study looks at how well the U.S. DOE's RRM model, E3SMv2.1‐Arctic, performs in simulating Arctic climate. The RRM, which focuses on the Arctic region, is compared to a uniform low‐resolution version, as well as to observations and reanalysis data. The RRM does a better job of simulating important Arctic climate features like precipitation, atmospheric circulation, clouds, sea ice and atmospheric rivers compared to the low‐resolution model. However, it shows some seasonal temperature biases, reducing the cold bias in summer but increasing the warm bias in winter. The RRM also underestimates winter sea ice, consistent with the warm winter bias. While the study demonstrates the advantages of using high‐resolution models to better understand Arctic climate changes, it also notes that some biases remain despite the increased resolution. Key Points Evaluation of atmosphere‐land‐ocean‐ice fully coupled E3SM‐Arctic historical simulations with regionally refined meshes for the Arctic E3SM‐Arctic reduces bias in precipitation, clouds and atmospheric rivers due to better topography compared to its low‐resolution counterpart Higher resolution leads to an increased albedo feedback and more accurate sea ice area, but with faster sea ice melting due to a warm bias

• Publisher: John Wiley & Sons, Inc,American Geophysical Union (AGU)
• Subject: Air temperature / air-sea ice-ocean interactions / Albedo / Arctic climate changes / Arctic climates / Arctic modeling / Atmosphere / Atmospheric boundary layer / Atmospheric circulation / Climate / Climate change / Climate feedback / Climatic analysis / Cryosphere / Cyclones / Energy Exascale Earth System Model (E3SM) / Ice / Ice thickness / Oceans / Precipitation / radiative feedbacks / regionally refined mesh / Sea ice / Sea ice thickness / Simulation / Surface temperature / Surface-air temperature relationships / Temperature / Wang, Chen / Winter