Observations of fresh, anticyclonic eddies in the Hudson Strait outflow

• Published in: Journal of Marine Systems
• Main Authors: Sutherland, David A., Straneo, Fiamma, Lentz, Steven J., St-Laurent, Pierre
• Format: Report
• Language: English
• Published: 2010
• Subjects: Hudson Strait; Hudson Bay; Labrador Current; Freshwater; Hudson; Labrador Shelf; Labrador Sea; North Atlantic
• Online Access: https://hdl.handle.net/1912/4903

Author Posting. © The Author(s), 2010. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Journal of Marine Systems 88 (2011): 375-384, doi:10.1016/j.jmarsys.2010.12.004. The waters that flow out through Hudson Strait, a coastal system that connects Hudson Bay with the Labrador Sea, constitute the third largest freshwater contribution to the northern North Atlantic. Recent studies have documented the mean structure and transport of the outflow, as well as highlighting significant variability on synoptic scales (days–week). This study examines the outflow’s variability on these synoptic scales through the use of observations collected by a mooring array from 2005-2006. We focus on the mechanisms that cause the freshwater export to be concentrated in a series of discrete pulses during the fall/winter season. We find that the pulses occur once every 4.4 days on average and are associated with anticyclonic, surface-trapped eddies propagated through the strait by the mean outflow. Their occurrence is related to the passage of storms across Hudson Bay, although local instability processes also play a role in their formation. The eddies are responsible for approximately 40% of the mean volume transport and 50% of the mean freshwater transport out of the strait. We discuss the implications of this freshwater release mechanism on the delivery of nutrient-rich and highly stratified waters to the Labrador shelf, a productive region south of Hudson Strait. This work was funded by National Science Foundation grant OCE-0751554, with additional funding from the Office of Naval Research grant N00014-08-10490.