Assessment of Satellite Altimetric and Compact Polarimetric SAR Parameters over Early Spring Snow-Covered Landfast Sea Ice in the Canadian Arctic

The snow cover on first-year sea ice is a critically under-observed parameter in the Arctic sea ice system, recognized by the World Meteorological Organization as an Essential Climate Variable due to its influence on energy exchange between the atmosphere and ocean through turbulent, radiative, and conductive processes. Measurements of snow properties are limited but present and future satellite missions provide opportunities for regular and continuous monitoring. This study explores the sub km- to km-scale spatial association between in-situ snow depth measurements, Cryo2ice satellite altimetric measurements and RADARSAT Constellation Misson compact polarimetric (CP) synthetic aperture radar (SAR) parameters over snow-covered landfast first-year sea ice in the Canadian Arctic Archipelago. In-situ snow depth measurements were collected at four unique sites along a 75 km track of near-coincidental Cryo2ice acquisitions in early spring 2022. We find that the Cryo2ice-retrived elevation difference (altimetric snow depth) can provide an estimate of snow depth on sea ice that is within one standard deviation (∼6 to 14 cm) of the in-situ measured values, particularly where the snow salinity is concentrated in the basal snow layer (bottom 2 cm). A statistically significant correlation (-0.77 to -0.85; p<0.01) is found between CP SAR backscatter coefficients at C-band and altimetric backscatter coefficients at Ku-band, particularly where there is low snow depth and smooth ice surface topography. Inconsistent statistical relationships are found between altimetric snow depth and CP SAR backscatter parameters that vary with snow and ice topography observed at the in-situ measurement sites.