Effects of the asymmetry between surface and interior flow on the dynamics of a thermohaline loop

Pollmann, Friederike; Roquet, Fabien; Madec, Gurvan. 2015 Effects of the asymmetry between surface and interior flow on the dynamics of a thermohaline loop. Journal of Physical Oceanography, 45 (10). 2544-2563. 10.1175/JPO-D-15-0022.1

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Text © Copyright 2015 American Meteorological Society (AMS). Permission to use figures, tables, and brief excerpts from this work in scientific and educational works is hereby granted provided that the source is acknowledged. Any use of material in this work that is determined to be “fair use” under Section 107 of the U.S. Copyright Act September 2010 Page 2 or that satisfies the conditions specified in Section 108 of the U.S. Copyright Act (17 USC §108, as revised by P.L. 94-553) does not require the AMS’s permission. Republication, systematic reproduction, posting in electronic form, such as on a web site or in a searchable database, or other uses of this material, except as exempted by the above statement, requires written permission or a license from the AMS. Additional details are provided in the AMS Copyright Policy, available on the AMS Web site located at (http://www.ametsoc.org/) or from the AMS at 617-227-2425 or copyrights@ametsoc.org. jpo-d-15-0022%2E1.pdf - Published Version Download (3MB) | Preview

Abstract/Summary

Large-scale overturning cells in the ocean typically combine an essentially horizontal surface branch and an interior branch below, where the circulation spans both horizontal and vertical scales. The aim of this study is to analyze the impact of this asymmetry between the two branches by “folding” a one-dimensional thermohaline loop, such that its lower part remains vertical while its upper part is folded down into the horizontal plane. It is found that both the transitory response and the distribution of thermohaline properties are modified significantly when the loop is folded. In some cases, velocity oscillations are induced during the spinup that were not seen in the unfolded case. This is because a circular loop allows for compensations between the density torques produced above and below the heat forcing level, while such compensations are not possible in the folded loop because of the horizontal direction of the surface circulation. Furthermore, the dynamical effects associated with nonlinearities of the equation of state are significantly altered by the folding. Cabbeling tends to decelerate the flow in the folded loop, instead of accelerating it as in the circular case, and can also act to dampen velocity oscillations. Thermobaricity also alters the loop circulation, although comparatively less.

Item Type:	Publication - Article
Digital Object Identifier (DOI):	10.1175/JPO-D-15-0022.1
ISSN:	0022-3670
Additional Keywords:	Circulation/Dynamics, Meridional overturning circulation, Nonlinear dynamics, Ocean dynamics, Atm/Ocean Structure/ Phenomena, Thermohaline circulation, Models and modeling, Ocean models, Applications, Education
Date made live:	18 Feb 2016 16:10 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/513018

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