The effect of grid resolution on sub-ice shelf circulation in the Energy Exascale Earth System Model

Global ocean models are typically too coarse to explicitly resolve physical processes, such as mesoscale eddies, that transport heat into ice-shelf cavities and contribute to melting. As a result, mesoscale processes around Antarctica in such models need to be parameterized. Here we investigate the performance of these parameterizations in the Energy Exascale Earth System Model (E3SM), specifically focusing on the heat transport into an ice shelf cavity, the strength and direction of sub ice shelf circulation, and the rate of basal melting. Taking advantage of E3SMs variable-resolution capabilities we set up a sequence of configurations with nominal grid sizes of 12, 8, 4, 2, and 1 km in the southern Weddell Sea, such that with increasing resolution, less eddies are parameterized and more resolved explicitly. The analysis is focused on the Filchner-Ronne Ice Shelf, because it is oceanographically interesting, it is important for sea level projections, and there are relatively abundant datasets from this region available for model validation.