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Reexamination of Fram Strait sea ice export and its role in recently accelerated Arctic sea ice retreat

Wei, Jianfen, Zhang, Xiangdong, Wang, Zhaomin
Climate dynamics 2019 v.53 no.3-4 pp. 1823-1841
North Atlantic Oscillation, atmospheric circulation, basins, climate, melting, models, sea ice, summer, wind, Arctic region
Using the high-resolution global ocean-sea ice model MITgcm-ECCO2, variability and changes of Arctic sea ice export through Fram Strait during 1979–2012 are examined. The simulated annual mean ice export is about 3216 km³/year, which is 12.7% of the 34-year averaged Arctic sea ice volume, with the maximum and minimum occurring in 1994/95 and 1984/1985, respectively. Winter (October–March) ice export is much more than summer (April–September) and exhibits a greater interannual variation. This study suggests that a significant regime shift of Fram Strait ice export from high to low value occurs around the mid-1990s. Further analysis shows that the regime shift of the atmospheric circulation from conventional Arctic Oscillation/North Atlantic Oscillation (AO/NAO) to the dipole-structure Arctic Rapid change Pattern (ARP) plays an important role on the regime shift of ice export. This shift of atmospheric circulation pattern dominates the variability of ice motion and changes the main source region of ice outflow. Combined with the decreased ice thickness and the less ice outflow related to the weakened northerly/northeasterly winds near the strait, sea ice export decreased, eventually generating a regime shift around the mid-1990s. The distinct impact of changes in Fram Strait ice export on the Arctic sea ice inside the basin before and after mid-1990s indicates that the recent continuing loss of Arctic sea ice was mainly induced by the accelerated ice melting in the Arctic Ocean, rather than the ice outflow through Fram Strait.