Restrictions on Deep Flow Across the Shelf-break and the Role of Submarine Canyons in Facilitating such Flow |
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| Authors: | Susan E Allen |
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| Institution: | (1) Department of Earth and Ocean Science, University of British Columbia, 6339 Stores Rd., Vancouver, BC, Canada, V6T1Z4 |
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| Abstract: | The shelf-break acts as a separator between the coastal ocean and the open ocean. Circulation (particularly deep near-bottom flow) is restricted from crossing the bathymetry. Eddies become elongated in the region of the shelf-break restricting exchange. An estimate of the horizontal eddy diffusivity over the shelf-break of less than 10m2s-1 is found from a numerical model. Various mechanisms are responsible for the weak cross-isobath flow that does occur. One is the increase of the Rossby number over small-scale topography such as submarine canyons. Along-shore flow (in the direction opposite to Kelvin wave propagation) generates upwelling through submarine canyons. A review of upwelling through submarine canyons is given. The deep cross-shelf flow generated by the canyons is shown to be as significant as the wind-driven upwelling in some regions. Examples for the reduction of flow across the shelf-break and for upwelling through canyons are taken from the West Coast of Vancouver Island. |
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| Keywords: | shelf-break subinertial flow submarine canyon topography upwelling |
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