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Accelerating dense-water flow down a slope

Huthnance, John M.. 2009 Accelerating dense-water flow down a slope. Journal of Physical Oceanography, 39 (6). 1495-1511. 10.1175/2008JPO3964.1

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Abstract/Summary

Where water is denser on a shallow shelf than in the adjacent deep ocean, it tends to flow down the slope from shelf to ocean. The flow can be in a steady bottom boundary layer for moderate combinations of up-slope density gradient -ρx∞ and bottom slope (angle θ to horizontal): b ≡ |ρx∞| g sinθ / (f**2 ρ0) < 1. Here g is acceleration due to gravity, ρ0 is a mean density and f is twice the component of earth’s rotation normal to the sloping bottom. For stronger combinations of horizontal density gradient and bottom slope, the flow accelerates. Analysis of an idealised initial-value problem shows that when b ≥ 1 there is a bottom boundary layer with down-slope flow, intensifying exponentially at a rate fb**2 (1+b)**-1/2 /2, and slower-growing flow higher up. For stronger stratification b > 2**1/2, i.e. relatively weak Coriolis constraint, the idealised problem posed here may not be the most apposite but suggests that the whole water column accelerates, at a rate [ρ0**-1 |ρx∞| g sinθ]**1/2 if f is negligible.

Item Type: Publication - Article
Digital Object Identifier (DOI): 10.1175/2008JPO3964.1
Programmes: POL Programmes > Shallow coastal seas - function and impacts of change
Oceans 2025 > Shelf and coastal processes
ISSN: 0022-3670
Additional Keywords: Boundary layer; gravity current; continental slope; cascade
NORA Subject Terms: Marine Sciences
Physics
Date made live: 06 Jul 2009 12:17
URI: http://nora.nerc.ac.uk/id/eprint/7240

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