Using a Snow Model to Map Antarctic Ice Sheet Surface Mass Balance at a 1-km Resolution

Accurately determining mass balance of the Antarctic Ice Sheet (AIS) is critical to estimates of future sea level change. Specifically, the spatial and temporal variability of surface mass balance (SMB) is a major contributor to uncertainties in AIS mass balance. Wind erosion heavily influences SMB on spatial scales that are smaller than those captured by atmospheric reanalyses, especially in the dry and windy ice sheet interior. To resolve these fine scale SMB variations, we can use a detailed physical model of snow processes. In this study, we apply a one-dimensional, multi-layered snow cover model (SNOWPACK) to the AIS, driven by hourly atmospheric data from the MERRA-2 reanalysis. In order to adapt this alpine model for use in Antarctic environments, the lower boundary temperature was set to MERRA-2 annual mean surface temperatures, and we designed a more realistic method of determining erosion during snow blowing events. For model evaluation and improvement, we derived relative accumulation rates from Operation IceBridge snow radar echograms over the West Antarctic ice sheet. Overall, MERRA-2 accumulation is well correlated with accumulation rates derived from the snow radar over the 2016 Thwaites/Pine Island Glacier flight. However, sub-MERRA-2 grid scale variability is notable from the snow radar-derived accumulation, which we aim to resolve using SNOWPACK. Future work will focus on running SNOWPACK in distributed mode, to generate a high-resolution (1 km) SMB product for the entire AIS.