The rapid increase in ice thickness along Nares Strait following ice arch formation

Abstract

Nares Strait, situated between northwest Greenland and Ellesmere Island, is an important conduit for the export of sea ice from the Arctic, including thick multi-year ice that is undergoing an accelerated loss.  This export is modulated by the presence of ice arches that can form along the strait, and that can remain stable for months at a time.  When an arch is present, there is no export of sea ice along the Strait.  The formation and stability of ice arches is a function of sea ice thickness. There is a concern that the observed thinning of Arctic sea ice may be weakening the arches, resulting in an accelerated loss of sea ice from the Arctic. However, little is known about sea ice thickness's spatial and temporal variability along the Strait.  Here we show that after an arch forms, ice motion continues north of the arch for a period of time that results in a rapid dynamical thickening of the sea ice in the vicinity of the arch. Over the period of a month after arch formation, the ice thickness may increase by up to 1.0m.     This dynamically driven increase in sea ice thickness may help explain why the arches remain stable once they form.