Seasonal Variability of Snow Stratigraphy and Spectral Optical Properties on Sea Ice

The optical properties of snow strongly influence the surface energy balance within the coupled atmosphere-ice- ocean system. They control the amount of solar short-wave radiation, reflected at the surface (surface albedo), scattered and absorbed within snow, and transmitted into the sea ice underneath. Snow stratigraphy and spectral transmission are crucial for biological studies on sea ice related communities and bio-chemical processes. Furthermore, the increasing importance of remote sensors for studying snow and sea ice in both Polar Regions raises the need of ground truth data of physical and. spectral optical snow and sea ice properties. We perform simultaneous spectral radiation and detailed snow stratigraphy measurements in various regions in the Arctic (Arctic Basin, Svalbard, Fram Strait) during different seasons. Time series of spectral albedo and transmission through snow and sea ice together with snow observations were gathered during drift stations and long term monitoring programs. These data sets give valuable information about the seasonal cycle of surface characteristics. For the optical measurements we are using high resolution ASD FieldSpec and TriOS Ramses radiometers. Snow studies are mainly based on systematic snow pit measurements of various properties, e.g. grain size, grain type, wetness, temperature complemented by photo documentary, thickness profiles, and physical properties of sea ice. Additionally, data analyses benefits from the application of the high resolution numerical snow model SNTHERM, which performs well in simulating snow properties on sea ice under various boundary conditions. Simulations are conducted for regions and times where in situ snow data are not available, and for performing detailed snow process studies.