The DOE E3SM Coupled Model Version 1: Overview and Evaluation at Standard Resolution
Authors: Golaz Jean‐Christophe , Caldwell Peter M. , Van Roekel Luke P. , Petersen Mark R. , Tang Qi , Wolfe Jonathan D. , Abeshu Guta , Anantharaj Valentine , Asay‐Davis Xylar S. , Bader David C. , Baldwin Sterling A. , Bisht Gautam , Bogenschutz Peter A. , Branstetter Marcia , Brunke Michael A. , Brus Steven R. , Burrows Susannah M. , Cameron‐Smith Philip J. , Donahue Aaron S. , Deakin Michael , Easter Richard C. , Evans Katherine J. , Feng Yan , Flanner Mark , Foucar James G. , Fyke Jeremy G. , Griffin Brian M. , Hannay Cécile , Harrop Bryce E. , Hoffman Mattthew J. , Hunke Elizabeth C. , Jacob Robert L. , Jacobsen Douglas W. , Jeffery Nicole , Jones Philip W. , Keen Noel D. , Klein Stephen A. , Larson Vincent E. , Leung L. Ruby , Li Hong‐Yi , Lin Wuyin , Lipscomb William H. , Ma Po‐Lun , Mahajan Salil , Maltrud Mathew E. , Mametjanov Azamat , McClean Julie L. , McCoy Renata B. , Neale Richard B. , Price Stephen F. , Qian Yun , Rasch Philip J. , Reeves Eyre J. E. Jack , Riley William J. , Ringler Todd D. , Roberts Andrew F. , Roesler Erika L. , Salinger Andrew G. , Shaheen Zeshawn , Shi Xiaoying , Singh Balwinder , Tang Jinyun , Taylor Mark A. , Thornton Peter E. , Turner Adrian K. , Veneziani Milena , Wan Hui , Wang Hailong , Wang Shanlin , Williams Dean N. , Wolfram Phillip J. , Worley Patrick H. , Xie Shaocheng , Yang Yang , Yoon Jin‐Ho , Zelinka Mark D. , Zender Charles S. , Zeng Xubin , Zhang Chengzhu , Zhang Kai , Zhang Yuying , Zheng Xue , Zhou Tian , Zhu Qing 
Published: March 2019

This work documents the first version of the U.S. Department of Energy (DOE) new Energy Exascale Earth System Model (E3SMv1). We focus on the standard resolution of the fully coupled physical model designed to address DOE mission‐relevant water cycle questions. Its components include atmosphere and land (110‐km grid spacing), ocean and sea ice (60 km in the midlatitudes and 30 km at the equator and poles), and river transport (55 km) models. This base configuration will also serve as a foundation for additional configurations exploring higher horizontal resolution as well as augmented capabilities in the form of biogeochemistry and cryosphere configurations. The performance of E3SMv1 is evaluated by means of a standard set of Coupled Model Intercomparison Project Phase 6 (CMIP6) Diagnosis, Evaluation, and Characterization of Klima simulations consisting of a long preindustrial control, historical simulations (ensembles of fully coupled and prescribed SSTs) as well as idealized CO2 forcing simulations. The model performs well overall with biases typical of other CMIP‐class models, although the simulated Atlantic Meridional Overturning Circulation is weaker than many CMIP‐class models. While the E3SMv1 historical ensemble captures the bulk of the observed warming between preindustrial (1850) and present day, the trajectory of the warming diverges from observations in the second half of the twentieth century with a period of delayed warming followed by an excessive warming trend. Using a two‐layer energy balance model, we attribute this divergence to the model's strong aerosol‐related effective radiative forcing (ERFari+aci = −1.65 W/m2) and high equilibrium climate sensitivity (ECS = 5.3 K).