Mapping of Active Frazil for Antarctic Coastal Polynyas, With an Estimation of Sea-Ice Production

The importance of the area of active frazil and associated high sea-ice production in Antarctic coastal polynyas has been increasingly recognized in recent in situ and high-resolution satellite observations. However, the occurrence and spatial distribution of active-frazil area are not well understood. We present the first mapping of active-frazil area for Antarctic coastal polynyas, based on the thin ice algorithm of AMSR-E that discriminates active-frazil area. Mapping of sea-ice production is presented by taking account of active-frazil area. Active-frazil area is predominant along East Antarctica, particularly very close to the coast, locally leading to very high ice-production rates exceeding 20 m/yr. For frazil-dominant polynyas, estimated ice production is similar to 20%-50% higher compared with previous studies. Analyses of all the major polynyas suggest that active-frazil extent depends on offshore wind and air temperature, while ice production is determined by offshore wind only.