Sea Ice Dynamics in Hudson Strait and Its Impact on Winter Shipping Operations

Hudson Strait is seasonally ice covered and is the only part of the Canadian Arctic where winter shipping takes place. Yet, very little is known about the thickness and dynamics of this ice pack. During winter operations, icebreakers often face besetting events, which can slow or immobilize vessels for up to a few days. Using in situ observations of ice draft and drift collected by moored sonars at two sites in Hudson Strait from 2005 to 2009, we provide the first detailed analysis of sea ice dynamics within Hudson Strait and provide insights into the processes that dictate ice thickness and internal pressure along this unique winter shipping corridor. Prevailing northwesterly winds drive south‐southeastward ice motion within the Strait, maintaining polynyas along Baffin Island on the north side of the Strait, and compressing the ice pack against Nunavik on the southern side. As a result, ice on the northern side remains young and thin throughout winter (x¯March ${\bar{x}}_{\text{March}}$ = 1.25 m), whereas ice on the southern side is older, heavily deformed and ∼60% thicker by March (x¯March ${\bar{x}}_{\text{March}}$ = 2.01 m). Intermittent reversals to southeasterly winds decompress the ice pack on the southern side, increasing the presence of leads and easing navigation through the ice pack to the port in Deception Bay. The spatial variability in sea ice thickness elucidated by the moorings is corroborated at the regional scale using satellite observations from ICESat‐2 during winter 2019, 2020, and 2021, and complimented by high‐resolution fields of sea ice motion during winter 2021. Plain Language Summary Hudson Strait is located in northeastern Canada, separating northern Quebec (Nunavik) from Baffin Island, and is seasonally covered by sea ice from December to June. The Strait is a key shipping corridor in the Canadian Arctic, and while most of the shipping occurs during the open water season (July–October), two ice breaking bulk carriers operate through the ice pack during winter. The vessels have a sufficient Polar Class rating (Polar Class 4, rated for year‐round operation in thick first year ice) for the regional ice pack, but ridges and pressured ice regularly slow the ships or cause them to become immobilized within the ice, causing delays and potentially hazardous conditions. Within this paper, we use in situ observations of ice thickness collected from oceanographic moorings between 2005 and 2009 to characterize ice thickness within Hudson