Physical processes affecting circulation and hydrography in the Sable Gully of Nova Scotia

The Sable Gully is the largest submarine canyon along the shelf break off the east coast of North America. The circulation and hydrography in the Gully have significant temporal and spatial variability. This paper presents a numerical study of the three-dimensional circulation and hydrography in the Gully using a multi-nested ocean circulation model. The model is forced by tides, wind stress and surface heat/freshwater fluxes. Model results are in fair agreement with the current and hydrographic observations made in the Gully in 2006 and 2007. A process study is conducted to examine the main physical processes affecting the circulation and hydrography, including tide–topography interaction, wind forcing, and the shelf-scale circulation over the eastern Canadian Shelf. The model results demonstrate that the circulation and hydrography above the canyon rim are influenced significantly by wind, particularly during storm events, while the subsurface flow over the shelf slope is affected by the shelf-scale circulation. There is also significant tide–topography interaction inside the Gully.