High-Resolution Modeling Captures Observed Kilometer-Scale Antarctic Accumulation Variability

Abstract:

Advances in satellite altimetry (e.g. ICESat-2 and CryoSat-2) allow us to measure ice sheet surface height change at horizontal scales of less than 1 km. However, widely used Antarctic surface mass balance and firn densification models have not kept pace with observational advances, thus limiting our ability to reliably convert observed surface height change into local mass change. For example, most models use relatively coarse horizontal resolutions (5.5 – 35 km), employ simplified firn densification models, and often do not include drifting snow processes. To improve model representation of local surface mass balance and snow processes, including densification and meltwater production and retention, we combine the detailed snow model SNOWPACK, MERRA-2 atmospheric reanalysis, and a new drifting snow scheme. We then leverage this unique combination to map surface mass balance at unprecedentedly high-spatial resolution (1 km) over Thwaites and Pine Island Glaciers in West Antarctica. We go on to show that our model captures observed kilometer-scale wind-driven snow accumulation variability not currently reproduced by existing models. Because our new surface mass balance product successfully captures kilometer-scale accumulation variability, it can be used to examine the spatial representativeness of ice core accumulation records, investigate local firn meltwater processes which may contribute to ice shelf instability, and calculate local mass change from satellite altimetry.