Deformation of the Arctic Ocean ice cover after the 2007 record minimum in summer ice extent

Abstract

We examine the deformation of the Arctic Ocean sea ice cover after the record minimum in summer extent in 2007. The period spans ~ 2.5 months between September 15 and December 1. Ice drift and deformation inside the ice edge, within a domain that initially covers ~ 0.76 × 10 6 km 2 of the western Arctic, are derived from high-resolution RADARSAT imagery from the Alaska Satellite Facility. Poleward of 80°N, we find a net convergence of more than 14% over the period. This large convergence is associated with the strength, location, and persistence of the Beaufort high-pressure pattern that led to prevailing on-shore winds north of Ellesmere Island and Greenland. This can be contrasted to the nearly 25% divergence of the ice cover, accompanied by a large regional vorticity of − 0.93 (or a clockwise rotation of ~ 53°) south of 80°N. The same atmospheric pattern produced openings as the ice cover drifts southwest towards the unconstrained ice-free part of the southern Beaufort and Chukchi Seas. These sustained strain rates, especially convergence, impacts the area and thickness distribution of the sea ice cover in the Arctic Basin. If unaccounted for, this deformation-induced decrease in ice coverage (in this region with predominantly multiyear ice) could be incorrectly ascribed to ice export with a concurrent decrease in Arctic sea ice volume, when in fact the ice volume is conserved but with a local redistribution in thickness. ► Examined deformation of the Arctic sea ice cover after the record minimum in summer extent in 2007. ► Ice drift and deformation derived from high-resolution RADARSAT imagery. ► Poleward of 80°N, we find a net convergence of more than 14% over the period. ► South of 80°N, there is a 25% divergence, accompanied by a large regional vorticity of − 0.93 (or a clockwise rotation of ~ 53°). ► These sustained strain rates, impacts the area and thickness distribution of the sea ice cover in the Arctic Basin.