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

• Main Authors: van Kampenhout, Leonardus, Rhoades, Alan M, Herrington, Adam R, Zarzycki, Colin M, Lenaerts, Jan TM, Sacks, William J, van den Broeke, Michiel R
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: eScholarship, University of California 2019
• Subjects: Earth Sciences; Physical Geography and Environmental Geoscience; Atmospheric Sciences; Climate Action; Oceanography; Meteorology & Atmospheric Sciences; Greenland; Ice Sheet; The Cryosphere
• Online Access: https://escholarship.org/uc/item/9mq493tf

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° (∼55km) and 0.25° (∼28km), maintaining a quasi-uniform resolution of 1° (∼111km) 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.