Experimental assessment of light propagation in the snowpack, RiS ID 12344

Snowpack is a key component in the Arctic regions. The albedo of freshly fallen snow is typically very high in the visible range (up to 0.9), playing a crucial role in Earth's energy balance. Snow albedo can eventually be reduced upon aging of snow crystals due to metamorphism and to the increasing presence of impurities (e.g., mineral dust and black carbon). Moreover, diverse reactions can occur in the snowpack driven by solar radiation, such as mercury emission, bromine oxidation and degradation of organic compounds. At present, snow albedo is measured by detecting the total light reflected by the snowpack, with almost no understanding of sunlight penetration through the snow. In fact, light penetration is almost only modelled numerically using rough approximations, without considering various snow properties. The lack of experimental data and dedicated studies leave a remarkable scientific gap in the snow research. The main aim of SNOWLIGHT is to address this issue on an experimental basis, exploiting a custom-made sensor entirely realized and calibrated within the Instrumental Optics Laboratory of the Physics Department at the University of Milan, specifically designed to better elucidate the propagation of sunlight in the snow. A tight experimentally-based approach will be adopted thus guaranteeing a model independent method to generate a reliable predictive tool. To achieve this goal, measurement will be conducted on glaciers the surroundings of Ny-Ålesund at different elevations, to assess the effect of different morphological and stratigraphical snow conditions, and on the sea ice close to Kongsvegen to explore the additional influence of algae beneath the surface. Field experiments will be complemented by snow pits, gathering data on physical and morphological layer-by-layer proprieties of the snowpack. In addition, snow samples will be collected to investigate the presence of impurities (MD/BC) and their chemical composition through further analyses.