Hudson Strait Inflow: Structure And Variability

Hudson Strait is the main pathway of heat, mass, and freshwater exchange between Hudson Bay and the Arctic and North Atlantic oceans. The outflow along the southern coast of the strait, a fresh, baroclinic jet directed toward the North Atlantic, has received more attention due to its potential impact on deep convection in the Labrador Sea. However, details about the westward, more barotropic inflow along the northern coast of Hudson Strait remain unknown due to a scarcity of observations. Hudson Strait inflow waters affect the physical and biogeochemical systems of the bay, as well as the marine ecosystem, which supports the livelihoods of many Indigenous communities surrounding the Hudson Bay region. Here, we address this knowledge gap by analyzing data from two hydrographic surveys and four moorings deployed across the strait from 2008 and 2009. Three moorings were deployed on the northern side of the strait to map the inflow, and one was deployed on the southern side of the strait to capture the outflow. Along the southern side, a stratified, fresh outflow was observed, consistent with earlier studies. Along the northern coast, the inflow is weakly stratified and more saline, with seasonal changes distributed throughout the water column. Source waters of the inflow stem mainly from Arctic Water in the Baffin Island Current. A comparison with historical data suggests that after modification in western Hudson Strait, part of the inflow enters northern Hudson Bay to become deep water in the bay.