A novel Antarctic Sea-Ice Velocity Retrieval Framework Based on FY-3D/MWRI Imagery

Sea-ice motion plays a pivotal role in the variability of the Antarctic climate system by modulating the atmosphere–ocean fluxes and the ocean freshwater budget. Due to the variability of the ice surface, snow–ice formation, as well as high speeds, remote sensing of sea-ice motion by passive microwave method presents higher uncertainty in the Antarctic than in the Arctic. Our study develops a novel sea-ice velocity (SIV) retrieval framework based on the pattern tracking method using FY-3D satellite microwave radiation imager (MWRI) 36 GHz brightness temperature (TB) data and acquired swath/daily-mean SIV data with 30-km spatial resolution in the Southern Ocean for the first time. Our framework has three advantages. It 1) employs 36 GHz TB for SIV retrieval both in winter and summer to ensure consistency in the spatial resolution of SIV; 2) uses swath TB image pairs with a consistent 24-h interval to keep SIV’s temporal consistency; and 3) combines template selection scheme and two-direction retrieval scheme to improve the accuracy of SIV. The SIV obtained using the new framework has the same spatial resolution throughout the year and its spatial coverage exceeds 88% of the sea ice area. Compared with OSI-455 daily SIV data, merged daily MWRI SIV shows an annual mean spatial correlation of 0.89 (0.88 in winter and 0.89 in summer). In summary, the SIV acquired by our novel framework has great potential in monitoring the variability of Antarctic sea-ice cover.