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Deep bottom mixed layer drives intrinsic variability of the Antarctic Slope Front

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Huneke, WGC ORCID: 0000-0001-8624-365X, Klocker, A ORCID: 0000-0002-2038-7922 and Galton-Fenzi, BK 2019 , 'Deep bottom mixed layer drives intrinsic variability of the Antarctic Slope Front' , Journal of Physical Oceanography, vol. 49 , pp. 3163-3177 , doi: 10.1175/JPO-D-19-0044.1.

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Abstract

The Antarctic Slope Front (ASF) is located along much of the Antarctic continental shelf break and helps to maintain a barrier to the movement of Circumpolar Deep Water (CDW) onto the continental shelf. The stability of the ASF has a major control on cross-shelf heat transport and ocean-driven basal melting of Antarctic ice shelves. Here, the ASF dynamics are investigated for continental shelves with weak dense shelf water (DSW) formation, which are thought to have a stable ASF, common for regions in East Antarctica. Using an ocean process model, this study demonstrates how offshore bottom Ekman transport of shelf waters leads to the development of a deep bottom mixed layer at the lower continental slope, and subsequently determines an intrinsic variability of the ASF. The ASF variability is characterized by instability events that affect the entire water column and occur every 5–10 years and last for approximately half a year. During these instability events, the cross-shelf density gradient weakens and CDW moves closer to the continent. Stronger winds increase the formation rate of the bottom mixed layer, which causes a subsequent increase of instability events. If the observed freshening trend of continental shelf waters leads to weaker DSW formation, more regions might be vulnerable for the ASF variability to develop in the future.

Item Type: Article
Authors/Creators:Huneke, WGC and Klocker, A and Galton-Fenzi, BK
Keywords: Antarctic Slope Front, ocean model, coastal flows, currents, fronts, ocean dynamics
Journal or Publication Title: Journal of Physical Oceanography
Publisher: Amer Meteorological Soc
ISSN: 0022-3670
DOI / ID Number: 10.1175/JPO-D-19-0044.1
Copyright Information:

© Copyright 2019 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 or that satisfies the conditions specified in Section 108 of the U.S. Copyright Act (17 USC §108) does not require the AMS’s permission. Republication, systematic reproduction, posting in electronic form, such as on a website 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. All AMS journals and monograph publications are registered with the Copyright Clearance Center (http://www.copyright.com). Questions about permission to use materials for which AMS holds the copyright can also be directed to permissions@ametsoc.org. Additional details are provided in the AMS Copyright Policy statement, available on the AMS website (http://www.ametsoc.org/CopyrightInformation).

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