Circulation and Hydrography of Canada's Coastal and Inland Waters

Canada has the longest coastline in the world, with vast continental shelves in the Atlantic, Arctic and Pacific, as well as huge inland freshwater systems across its continent. The coastal and inland waters have diverse ecosystems and ample resources that are vital to Canadians. Monitoring, understanding and predicting the physical variability and trends in Canada’s coastal and inland waters have long been priorities for Fisheries and Oceans Canada, Environment Canada and Canadian academia. The demand for knowledge of the physical environment in coastal and inland waters is even more compelling under a changing climate in response to both natural and anthropogenic forcing. There are numerous issues related to the physical environment of coastal and inland waters, such as climate change impacts, aquaculture, pollution and transportation. Every year, the Congress of the Canadian Meteorological and Oceanographic Society (CMOS) hosts a theme session “Coastal Oceanography and Inland Waters,” with overwhelming contributions and interest from Canadian oceanographers and limnologists. This special section includes five research papers focused on circulation and hydrography. They were originally presented as part of the Coastal Oceanography and Inland Waters session at the 44 CMOS Congress held in Ottawa in June 2010. Placentia Bay is located off the south coast of Newfoundland and is host to diverse marine ecosystems, viable commercial fisheries, emerging aquaculture and heavy marine traffic including oil tankers. Because of the heavy marine traffic, the risk of oil spills is high in Placentia Bay. Ma et al. (2012) developed a three-dimensional baroclinic circulation model for Placentia Bay. They showed that the model is able to simulate tides accurately and sub-tidal sea level and currents approximately. The model reproduces well the vertical structure of temperature, the temporal evolution of stratification and the coastal upwelling, which are important physical features having significant implications for the survival and growth of fish larvae in the bay. The Bay of Fundy has the largest tidal range in the world. This large tidal range always plays a role in flooding events along its coastal region. Greenberg et al. (2012) showed that the tidal range is increasing in the Bay of Fundy, because of the rise in mean sea level in response to climate change. They predicted that the compounding effects of mean sea level rise and the increase in tidal range will lead to a drastic increase in flood risk in the twenty-first century. The eastern Canadian Shelf is located in the western boundary confluence zone of the North Atlantic between the subpolar and subtropical gyres. The circulation and hydrography in this large shelf system is predominately influenced by the Labrador Current as part of the subpolar gyre and the Gulf Stream and the North Atlantic Current. Urrego-Blanco and Sheng (2012) investigated the main physical processes governing the interannual variability of circulation using a coupled ice–ocean model. They found varying mechanisms underlying the interannual variability for different regions (e.g., dominant advective effects of high-latitude variability over the Labrador and northern Newfoundland shelves and strong influences of the Gulf Stream in the Slope Water region off Nova Scotia). The Discovery Islands are located between the British Columbia mainland and Vancouver Island. The region, with its numerous fjords and narrow channels, is characterized by strong tidal currents and prominent wind-driven and freshwater-driven flows. With the development of the salmon aquaculture in the region, there is an increasing need to understand the circulation patterns that affect the dispersion of organisms and pollutants. Foreman et al. (2012) developed a three-dimensional model for this region. The simulation for April 2010 produces accurate tidal elevations and approximate surface tidal currents. It shows that the tidal residual is significant in the mean current, but the wind-driven component is not. The model produced numerous residual and transient eddies that may have important implications for retention of organisms and pollution. Great Bear Lake, which crosses the Arctic Circle, is one of the polar lakes that are highly sensitive to climate change. Rao et al. (2012) simulated the physical processes affecting the lake temperature and stratification and assessed the climate change impacts on them during the ice-free period using a three-dimensional hydrodynamic model. It predicts an increase in the surface temperature of 0.5° to 2C between the 1970–2000 base climate and the 2041–70 warming climate. The increase appears to result mainly from the changes in the air–lake temperature gradient and the wind speeds in the warming climate. Finally, I would like to thank guest editors Jinyu Sheng and Yerubandi R. Rao, the authors, reviewers and staff of AtmosphereOcean and Taylor & Francis for their contributions to this special section.