Mapping Sea Ice Concentration in the Canadian Arctic with CryoSat-2

Abstract. Sea ice concentration (SIC) is an essential parameter for understanding environmental change in the polar regions. Historically, SIC has been determined using satellite passive microwave (PMV) radiometry, and this has revealed a progressive decline in the extent of the ice cover in the Arctic since records began in 1979. At regional and local scale, classifications based on satellite radar and optical imagery are practical. Here, we use CryoSat-2 to derive a new SIC product in the Canadian Arctic (CA), a region that is vital for shipping, freshwater production, and multi-year ice transport but is frequently excluded from pan-Arctic sea ice satellite observations. The 300 m along-track sampling of CryoSat-2 allows the fine-scale distribution of sea ice to be resolved, and an empirical correction for the overestimation of leads and misclassification of floes allows SIC to be determined. In general, spatial and temporal variations in SIC determined from CryoSat-2 are in close agreement with those determined from PMV and synthetic aperture radar (SAR) imagery in ice charts. Across the CA region, the root mean square difference (RMSD) between SIC determined monthly from CryoSat-2 and PMV and weekly from ice charts are 8.4 and 10 %, respectively. A local comparison to SIC determined from 82 cloud-free Landsat 8 scenes acquired in the central CA shows an RMSD of 3.3 %. Our findings highlight the complementarity of SIC records determined from CryoSat-2 and their potential to expand our knowledge of ice conditions in the CA.