Only satellite remote sensing can provide the pan-Arctic view required to fully understand changes to the Earth’s sea ice fields but important observational gaps remain which limit both our interpretation of remote-sensing data and our understanding of the Arctic climate system. In that regard, snow on sea ice represents both a major source of uncertainty in sea ice concentration and thickness retrievals from satellite data, and a poorly resolved quantity of climatic importance. The overarching objective of this proposal is to address these issues and to produce a state of the art now on sea ice thickness and density product. To achieve this goal we will use data from the most advanced and recent EO missions, namely ESA's ERS, Envisat, CryoSat-2 and SMOS missions as well as NASA's ICESat mission and ISRO and CNES' AltiKa mission.

We will utilize a comprehensive array of airborne and in-situ snow measurements to develop and validate two independent approaches to snow thickness retrieval on Arctic sea ice. In the Dual-altimeter Snow Thickness (DuST) product, we will utilize data from multiple contemporary satellite altimeters to derive information about the snow layer. In the SNOw on Drifting Sea Ice (SnoDSI) product we will utilize satellite-derived sea ice drift and precipitation from atmospheric reanalysis to build a package that accumulates, redistributes and melts snow on individually tracked ice parcels at daily resolution. Because of the impact of the snow thickness and density estimates for Envisat, ICESat and CS2 sea ice thickness retrievals this proposal will feed in the Arctic+ Theme 2: Arctic Sea Ice Mass intercomparison project. In addition the total snow water equivalent is an important source of freshwater in the Arctic and will also inform the Arctic+ Theme 3: Freshwater fluxes project or equivalent ongoing studies.