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Eddy Generation and Jet Formation via Dense Water Outflows across the Antarctic Continental Slope

Stewart, Andrew L. and Thompson, Andrew F. (2016) Eddy Generation and Jet Formation via Dense Water Outflows across the Antarctic Continental Slope. Journal of Physical Oceanography, 46 (12). pp. 3729-3750. ISSN 0022-3670. http://resolver.caltech.edu/CaltechAUTHORS:20170202-075554464

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Abstract

Along various stretches of the Antarctic margins, dense Antarctic Bottom Water (AABW) escapes its formation sites and descends the continental slope. This export necessarily raises the isopycnals associated with lighter density classes over the continental slope, resulting in density surfaces that connect the near-freezing waters of the continental shelf to the much warmer circumpolar deep water (CDW) at middepth offshore. In this article, an eddy-resolving process model is used to explore the possibility that AABW export enhances shoreward heat transport by creating a pathway for CDW to access the continental shelf without doing any work against buoyancy forces. In the absence of a net alongshore pressure gradient, the shoreward CDW transport is effected entirely by mesoscale and submesoscale eddy transfer. Eddies are generated partly by instabilities at the pycnocline, sourcing their energy from the alongshore wind stress, but primarily by instabilities at the CDW–AABW interface, sourcing their energy from buoyancy loss on the continental shelf. This combination of processes induces a vertical convergence of eddy kinetic energy and alongshore momentum into the middepth CDW layer, sustaining a local maximum in the eddy kinetic energy over the slope and balancing the Coriolis force associated with the shoreward CDW transport. The resulting slope turbulence self-organizes into a series of alternating along-slope jets with strongly asymmetrical contributions to the slope energy and momentum budgets. Cross-shore variations in the potential vorticity gradient cause the jets to drift continuously offshore, suggesting that fronts observed in regions of AABW down-slope flow may in fact be transient features.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1175/JPO-D-16-0145.1DOIArticle
http://journals.ametsoc.org/doi/10.1175/JPO-D-16-0145.1PublisherArticle
Additional Information:© 2016 American Meteorological Society. Manuscript received 15 June 2016, in final form 21 September 2016. Published online 15 December 2016. ALS’s research was supported by NSF Award OCE-1538702. AFT’s research was funded by NSF Award OPP-124646. Some of the simulations presented herein were conducted using the CITerra computing cluster in the Division of Geological and Planetary Sciences at the California Institute of Technology, and the authors thank the CITerra technicians for facilitating this work. The data presented in this article are available from the authors on request. The authors gratefully acknowledge the modeling efforts of the MITgcm team. The authors also thank Tore Hattermann and an anonymous reviewer for many constructive comments that improved the manuscript.
Funders:
Funding AgencyGrant Number
NSFOCE-1538702
NSFOPP-124646
Record Number:CaltechAUTHORS:20170202-075554464
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20170202-075554464
Official Citation:Stewart, A. and A. Thompson, 2016: Eddy Generation and Jet Formation via Dense Water Outflows across the Antarctic Continental Slope. J. Phys. Oceanogr., 46, 3729–3750, doi: 10.1175/JPO-D-16-0145.1.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:73976
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:02 Feb 2017 16:03
Last Modified:02 Feb 2017 16:03

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