Summary

  • The CAT study is an innovative and risky exploration in remote ice-covered waters of the Canadian High Arctic. Observations are recorded within autonomous submerged instruments which must be retrieved to collect data
  • Three arrays of these instruments were placed in August 2007. All instruments and two years of observations, a complete IPY data set, were successfully recovered in August 2009
  • We now have values for CAT, water flow of 1.75 million cubic metres per second (totaling 55,000 cubic kilometres per year), freshwater flow of about 115,000 cubic metres per second (totaling 3,600 cubic kilometres per year)
  • About 45% of the CAT moves through Nares Strait, 15% through Cardigan Strait plus Hell Gate and 40% through Lancaster Sound. About 40% of the seawater component comes from the nutrient-rich Pacific Ocean and the remainder from the Atlantic
  • The through-flows move in relatively narrow (10 km) ‘rivers’ that do not fill the full width of the straits
  • The NEMO (Nucleus for European Modeling of the Ocean) numerical simulation model has been configured for the Canadian Archipelago (bathymetry, initial conditions, boundary conditions, forcing)
  • The model suggests that the average flow through the Canadian Archipelago is driven by a small (approximately 10 cm) difference in sea level between the Beaufort Sea and Baffin Bay
  • When ice is free to drift, CAT is enhanced as much as 80% by strong winds that result when air flow funnels through Canadian Arctic straits. Beneath a stationary ice canopy of winter, however, the flow is isolated from the force of wind and slowed down by friction against the ice,
  • Observations suggest that rate of flow through Parry Channel is influenced by changing winds in the Beaufort Sea, which pile water against the western shores of the Archipelago
  • Very thick old sea ice remains common in the Canadian High Arctic, despite the large recent decrease in the abundance of such ice in the Arctic Ocean