A review of the role of submarine canyons in deep-ocean exchange with the shelf

[摘要] Cross shelf-break exchange is limited by the tendency of geostrophic flow tofollow bathymetric contours, not cross them. However, small scale topography,such as canyons, can reduce the local lengthscale of the flow and increasethe local Rossby number. These higher Rossby numbers mean the flow is nolonger purely geostrophic and significant cross-isobath flow can occur. Thiscross-isobath flow includes both upwelling and downwelling due to wind-drivenshelf currents and the strong cascading flows of dense shelf-water into theocean. Tidal currents usually run primarily parallel to the shelf-breaktopography. Canyons cut across these flows and thus are often regions ofgeneration of strong baroclinic tides and internal waves. Canyons can alsofocus internal waves. Both processes lead to greatly elevated levels ofmixing. Thus, through both advection and mixing processes, canyons canenhance Deep Ocean Shelf Exchange. Here we review the state of the sciencedescribing the dynamics of the flows and suggest further areas of research,particularly into quantifying fluxes of nutrients and carbon as well as heatand salt through canyons.

[学科分类] 海洋学与技术