Comparison of Ascat Estimated Snow Thickness on First-Year Sea Ice in the Canadian Arctic with Modeled and Passive Microwave Data

Abstract

The snow cover on sea ice is an important parameter controlling heat and momentum fluxes in our polar regions. Our understanding of snow thickness distributions on sea ice is severely limited by its vastness and numerous logistical difficulties. As such, we rarely collect enough in situ data from similar geographic locations to determine if and how the snow thickness distribution changes spatiotemporally. Geophysical changes in snow cover manifest as differences in dielectric properties, which are detectable in microwave emission and backscatter. Active microwave remote sensing offers improved spatial resolution when compared to passive microwave approaches. We apply our recently developed method that exploits the indirect thermodynamic control of the snow cover on near ice surface geophysical properties. The variance of C-band (5.3 GHz HH-polarization) microwave backscatter in winter (prior to melt) is assessed and is then used to estimate relative snow cover thickness and distribution. We assess the capability of our approach over landfast, first-year sea ice in the Canadian Arctic Archipelago and evaluate and compare our method against the Canadian Regional Ice Ocean Prediction system and AMSR2 passive microwave snow thickness estimates. Results demonstrate that this method can separate thick snow from thin snow on thick FYI within a thickness range of 5 to 45 cm at a spatial resolution of less than 5 km.