Buoyancy-forced circulations around islands and ridges

Author: Spall M.A.

Source: Journal of Marine Research, Volume 58, Number 6, 1 November 2000 , pp. 957-982(26)

Publisher: Sears Foundation for Marine Research

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Abstract:

Observations, theory, and modeling studies indicate that dominant components of both the upwelling and downwelling limbs of the thermohaline circulation take place near boundaries and in regions of steep and/or rough topography. Analytic and numerical results are used here to show that the interaction of upwelling regions with lateral boundaries fundamentally alters the resulting large-scale circulation compared to cases of open ocean upwelling. For narrow upwelling regions, viscous fluxes emerge as a leading term in the potential vorticity budget. The strong horizontal recirculation gyres that are found for sub-basin-scale open ocean upwelling ( beta

-plumes) are replaced by weak, unidirectional flow into or out of the region of vertical motion. If the upwelling is located near an island or mid-ocean ridge, potential vorticity budgets require that a strong, large-scale recirculation develop around the topography, sometimes far from the region of mixing. The resulting boundary layers provide an important dynamic link between the large-scale horizontal components of the thermohaline circulation and the small-scale regions of strong vertical motions.

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Document Type: Research article

DOI: http://dx.doi.org/10.1357/002224000763485764

Publication date: 2000-11-01

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