Observations of sea-ice deformation and floe interaction from satellite observations and airborne laser scanner surveys during MOSAiC

Arctic sea ice is a mosaic of ice floes whose distribution greatly impacts the interaction of sea ice with the atmosphere and the ocean. However, we are still lacking physics to describe the complex interplay of ice floes that are a key characteristic of sea ice. Kilometer-scale satellite and buoy observations have been used to describe the deformation of sea-ice as a continuum of floes, whereas ice fracture of individual floes has been studied in laboratory and field experiments. In our contribution, we aim to bridge this gap and outline a framework to characterize sea-ice deformation at the floe-scale from observational data by studying the mechanical interaction of multiple identifiable floes. We use Sentinel SAR imagery and airborne laser scanner surveys acquired during the MOSAiC expedition to map ice floes in the larger area around Polarstern. This combination of data products allows us to describe the floe-size distribution from hundreds of kilometers down to the meter-scale. With the repeated coverage of both data products, ice motion is tracked and deformation estimates are derived. By combining both floe-size estimates and deformation rates we provide insights into how the floe composition changes in regions that were exposed to deformation. This relationship between floe sizes and mechanical redistribution could constrain parameterizations to improve the representation of sea-ice deformation and floe sizes in large-scale continuum models. Finally, we highlight the potential to use the presented floe and deformation information to initialise and evaluate floe-resolving sea-ice simulations using discrete element models.