Sea Ice Dynamics in Foxe Basin: Formation of a Thick Dirty Seasonal Ice Cover along a Proposed Year-Round Shipping Route

Foxe Basin is a shallow inland sea in the Canadian Arctic that has strong tidal dynamics and is covered by a notoriously deformed and dirty sea ice cover for 9 months a year. Observations are limited, but the proposed development of year-round shipping to Steensby Inlet in northern Foxe Basin makes it imperative to characterize the ice pack. Using a new processing scheme to improve standard estimates of ice thickness from ICESat-2 we provide the first detailed examination of the regional sea-ice dynamics. Ice thickness varies considerably across the Basin, from thin ice in the polynyas of western Foxe Basin to ice thicker than 6 m in eastern Foxe Basin. The prevailing north-northwesterly winds drive much of this asymmetry, while tidal dynamics amplify deformation throughout Foxe Basin, particularly in the east where tidal ranges reach 5 m during winter. Tides promote the formation of thick, sediment-laden ice in tidal flaw leads, which form in shallow coastal waters, and tidal-bathymetry polynyas. These areas of persistent low sea ice concentrations within the ice pack are suggested to be the result of divergent ice drift caused by shallow bathymetry. Ice thickness along the proposed shipping route is interpreted with recommendations for future observations.