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

Coupled atmosphere-land simulations are performed on two regionally refined grids over Greenland at 0.5 degrees (similar to 55 km) and 0.25 degrees (similar to 28 km), maintaining a quasi-uniform resolution of 1 degrees (similar to 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.