Comparing Winter and Summer Simulated Estuarine Circulations in Foxe Basin, Canada

作者：Defossez M^*; Saucier F J; Myers P G; Caya D; Dumais J F

来源：Atmosphere-Ocean, 2012, 50(3): 386-401.

DOI：10.1080/07055900.2012.693256

• estuarine dynamics
• ice circulation
• polynyas
• salt budget
• buoyancy fluxes
• positive-negative estuaries
• inland seas

Foxe Basin is an Arctic inland sea located at the north of the Hudson Bay system (Canada). The characteristics of its estuarine circulation in winter differ from those in summer, mainly because of the sea-ice formation and cover. Using Lagrangian tracers and flux calculations from simulated data through a section at the outlet of the basin, we have shown that one-third of all the ice produced in winter is eventually exported toward the Labrador Sea. Foxe Basin is also a place where, in winter, latent heat polynyas to the west coexist with sensible heat polynyas around southwestern Foxe Peninsula, the latter resulting from an upwelling of intermediate water approximately 0.6 degrees C above the freezing point of seawater. Sea ice affects circulation in the basin by adding friction at the surface layer and by shielding the sea surface from the atmosphere, which leads to an average reduction of 11% in the surface currents. Sea ice also extracts approximately 1.3 x 10(14) kg of fresh water from the sea surface. Divided by Foxe Basin's surface area (0.2 x 10(12) m(2)) and by the freshwater density, this mass represents a mean layer of 0.65 m of fresh water. The salt transport anomaly versus depth at the outlet of the basin and the mean vertical buoyancy flux were also examined; this confirmed previous assumptions that the estuarine circulation forms a positive (summer)-negative (winter) couple. We suggest that the sensitivity of this couple to climate change may be used as a proxy to evaluate the impact of global warming in Foxe Basin.

• 出版日期2012