Regional grid refinement in an Earth system model: impacts on the simulated Greenland surface mass balance

• Published in: The Cryosphere
• Main Authors: van Kampenhout, Leonardus, Rhoades, Alan M., Herrington, Adam R., Zarzycki, Colin M., Lenaerts, Jan T. M., Sacks, William J., van den Broeke, Michiel R.
• Language: unknown
• Published: 2023
• Subjects: 54 ENVIRONMENTAL SCIENCES; Greenland; Ice Sheet
• Online Access: http://www.osti.gov/servlets/purl/1542412; https://www.osti.gov/biblio/1542412; https://doi.org/10.5194/tc-13-1547-2019

In this study, the resolution dependence of the simulated Greenland ice sheet surface mass balance (GrIS SMB) in the variable-resolution Community Earth System Model (VR-CESM) is investigated. Coupled atmosphere–land simulations are performed on two regionally refined grids over Greenland at 0.5° (~55 km) and 0.25° (~28 km), maintaining a quasi-uniform resolution of 1° (~111 km) over the rest of the globe. On the refined grids, the SMB in the accumulation zone is significantly improved compared to airborne radar and in situ observations, with a general wetting (more snowfall) at the margins and a drying (less snowfall) in the interior GrIS. Total GrIS precipitation decreases with resolution, which is in line with best-available regional climate model results. In the ablation zone, CESM starts developing a positive SMB bias with increased resolution in some basins, notably in the east and the north. The mismatch in ablation is linked to changes in cloud cover in VR-CESM, and a reduced effectiveness of the elevation classes subgrid parametrization in CESM. Overall, our pilot study introduces VR-CESM as a new tool in the cryospheric sciences, which could be used to dynamically downscale SMB in scenario simulations and to force dynamical ice sheet models through the CESM coupling framework.