The Role of Topography in Cross-Shelf-Break Tracer Exchange

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The rotation of the Earth and its Coriolis force limit the exchange of water between the coastal ocean and the deep ocean. This limited exchange is often illustrated by significant changes in water properties, such as colour, near the location of the shelf-break. Various processes can break these dynamical constraints and allow exchange flow. One of these is caused by small scale topography such as underwater canyons. We propose to quantify the amount of specific, environmentally important tracers that are transported through submarine canyons. These tracers include nitrate (a limiting nutrient for plankton growth), dissolved inorganic carbon (which can be upwelled and increase the flux of CO2 to the atmosphere), and water containing low oxygen (which can cause anoxia on the shelf). We will include the impact of the enhanced mixing that occurs in canyons and the impact of flow interactions among multiple canyons or between canyons and headlands. Our goal is to determine the net impact of multiple canyons on tracer flux in a shelf region over seasonal cycles.