Atmospheric influence on Arctic marginal ice zone position and width in the Atlantic sector, February–April 1979–2010

Arctic marginal ice zone (MIZ) widths in the Atlantic sector were measured during the months of maximum sea ice extent (February–April) for years 1979–2010 using a novel method based on objective curves through idealized sea ice concentration fields that satisfied Laplace’s equation. Over the record, the Labrador Sea MIZ (MIZ_L) had an average width of 122 km and narrowed by 28 % while moving 254 km poleward, the Greenland Sea MIZ (MIZ_G) had an average width of 98 km and narrowed by 43 % while moving 158 km west toward the Greenland coast, and the Barents Sea MIZ (MIZ_B) had an average width of 136 km and moved 259 km east toward the Eurasian coast without a trend in width. Trends in MIZ position and width were consistent with a warming Arctic and decreasing sea ice concentrations over the record. Beyond the trends, NAO-like atmospheric patterns influenced interannual variability in MIZ position and width: MIZ_L widened and moved southeast under anomalously strong northerly flow conducive to advection of sea ice into the Labrador Sea, MIZ_G widened and moved northeast under anomalously weak northerly flow conducive to diminishing the westward component of sea ice drift, and MIZ_B widened and moved poleward at the expense of pack ice under anomalously strong southwesterly flow conducive to enhancing oceanic heat flux into the Barents Sea. In addition, meridional flow anomalies associated with the NAO per se moved MIZ_B east and west by modulating sea ice concentration over the Barents Sea.