Subseasonal Earth system prediction with CESM2

• Published in: Weather and Forecasting
• Other Authors: Richter, Jadwiga H. (author), Glanville, Anne A. (author), Edwards, James (author), Kauffman, Brian (author), Davis, Nicholas A. (author), Jaye, Abigail (author), Kim, Hyemi (author), Pedatella, Nicholas M. (author), Sun, Lantao (author), Berner, Judith (author), Kim, Who M. (author), Yeager, Stephen G. (author), Danabasoglu, Gokhan (author), Caron, Julie M. (author), Oleson, Keith W. (author)
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2022
• Subjects: North Atlantic; North Atlantic oscillation
• Online Access: https://doi.org/10.1175/WAF-D-21-0163.1

Prediction systems to enable Earth system predictability research on the subseasonal time scale have been developed with the Community Earth System Model, version 2 (CESM2) using two configurations that differ in their atmospheric components. One system uses the Community Atmosphere Model, version 6 (CAM6) with its top near 40 km, referred to as CESM2(CAM6). The other employs the Whole Atmosphere Community Climate Model, version 6 (WACCM6) whose top extends to similar to 140 km, and it includes fully interactive tropospheric and stratospheric chemistry [CESM2(WACCM6)]. Both systems are utilized to carry out subseasonal reforecasts for the 1999-2020 period following the Subseasonal Experiment's (SubX) protocol. Subseasonal prediction skill from both systems is compared to those of the National Oceanic and Atmospheric Administration CFSv2 and European Centre for Medium-Range Weather Forecasts (ECMWF) operational models. CESM2(CAM6) and CESM2(WACCM6) show very similar subseasonal prediction skill of 2-m temperature, precipitation, the Madden-Julian oscillation, and North Atlantic Oscillation to its previous version and to the NOAA CFSv2 model. Overall, skill of CESM2(CAM6) and CESM2(WACCM6) is a little lower than that of the ECMWF system. In addition to typical output provided by subseasonal prediction systems, CESM2 reforecasts provide comprehensive datasets for predictability research of multiple Earth system components, including three-dimensional output for many variables, and output specific to the mesosphere and lower-thermosphere (MLT) region from CESM2(WACCM6). It is shown that sudden stratosphere warming events, and the associated variability in the MLT, can be predicted similar to 10 days in advance. Weekly real-time forecasts and reforecasts with CESM2(CAM6) and CESM2(WACCM6) are freely available. Significance StatementWe describe here the design and prediction skill of two subseasonal prediction systems based on two configurations of the Community Earth System Model, version 2 (CESM2): CESM2 with the ...