Sea ice draft observations in Nares Strait from 2003 to 2012

Abstract

Time series observation of sea ice draft and velocity from Nares Strait between 2003 and 2012 provides new insights on the statistical properties of sea ice leaving the Arctic for the Atlantic Oceans. Median ice draft is 0.8 m, but it varies annually from 1.5 m in 2007–2008 to 0.5 m in 2008–2009. Probability density distributions of sea ice draft depend on location across the channel with thicker ice near Canada and thinner ice near Greenland. Nevertheless, sea ice motion stops seasonally due to arching land-fast ice that spans the 30–40 km wide channel for up to 190 days per year such as during the 2011–2012 winter. In contrast, the 2006–2010 period exhibits a single ice arch lasting 47 days in April/May 2008. Hence sea ice statistics are weighted by space not by time, using sea ice velocities estimated from colocated velocity observations. Multiyear sea ice with drafts exceeding 5 m constitute between 9% (2003–2004) and 16% (2007–2008) of the observed sea ice. The probability g(D) of this thick, ridged, multiyear ice decays exponentially with draft D at an e-folding scale D0 of 3.0 ± 0.2 m. The trend of D0 with time is statistically indistinguishable from zero. This observation suggests a steady export of multiyear sea ice at decadal time scales. We speculate that our observations document the draining of the last reservoir of thick ice from the Arctic Ocean found to the north of Ellesmere Island and Greenland.