Observations of snow cover processes on Antarctic sea ice from in-situ and model studies

The snow cover on Antarctic sea ice impacts the energy, mass, and momentum balance of the sea ice cover, which in turn strongly influences fluxes between ocean, sea ice, and atmosphere. Despite the fact that snow depth is qualified as an Essential Climate Variable, the knowledge of the snow cover distribution and properties is still mostly vague and no large-scale (e.g. Antarctic wide) snow depth data product is available. Snow on Antarctic sea ice is characterized through a high spatial and temporal variability, and shows a highly heterogeneous internal stratification. This poses a challenge to air or space borne snow depth retrieval algorithms. Similarly, sea ice models are not yet able to resolve snow processes with enough accuracy. Here we present measurements of snow depth and physical snow properties along drift trajectories of autonomous Snow Buoys, which were deployed during several Polarstern cruises in the Weddell Sea since 2014. Resulting time series of snow depth show an event driven snow accumulation even during austral summer, whereas melting and a significant decrease of snow depth is only observed along the marginal sea ice zone. Additional analysis with the 1D multi-layer thermodynamic snow model SNOWPACK provides insights into internal processes such as snow to ice development cover along the trajectories. For these studies, SNOWPACK, which was previously used for land-based snow, has been extended with a sea ice module and is forced with re-analysis data. Comparisons between model and in-situ measurements show the capability of the model to reproduce the prevalent snow stratigraphy