The sea-ice compactness in the Greenland and Barents Seas during 1979-2003: Changes and links to the surface air flow

Abstract

Annual and winter (December-April) sea-ice area and extent are calculated for the Greenland Sea (GS) and Barents Sea (BS) from daily ice concentrations obtained from space-borne microwave radiometry for 1979-2003. The ice extent decreases significantly, particularly during winter, by 65 000 km2 (decade)-1 in the GS and by 72 000 km2 (decade)-1 in the BS. Ice-extent fractions (of these total extents) occupied by ice of five different ice-concentration ranges are calculated and analyzed. Changes in these fractions are again significant and most pronounced during winter. In the GS, the fraction of close to very compact ice (65-95%) decreases by 17 000 km2 (decade)-1 and the fraction of very compact ice (>95%) increases by 29 000 km2 (decade)-1, corresponding to a loss of 19% and a gain of 58% relative to the 25 year mean, respectively. In the BS, the fraction of close to compact ice (65-85%) increases by 26 000 km2 (decade)-1 and the fraction with compact to very compact ice (>85%) decreases by 66 000 km2 (decade)-1, corresponding to a gain of 30% and a loss of 67% relative to the 25 year mean, respectively. The changing surface wind pattern analyzed from ERA-40 data favours this increasing (decreasing) ice compactness in the GS (BS).