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arrested Agulhas retroflection

Title: The arrested Agulhas retroflection.
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Name(s): Nof, Doron, author
Zharkov, Volodymyr, 1963-, author
Ortiz, Joseph, author
Paldor, Nathan, author
Arruda, Wilton, author
Chassignet, E., author
Type of Resource: text
Genre: Text
Issuance: serial
Date Issued: 2011
Physical Form: computer
online resource
Extent: 1 online resource
Language(s): English
Abstract/Description: Paleoceanographic proxy data indicate that the Agulhas leakage into the South Atlantic was dramatically reduced during glacial times. In our former papers, we suggested that this was due to a northward shift of the zero wind stress curl that, in turn, forced the retroflection to occur farther north, where the slant of the coastline relative to the north is steep. In the present paper, we propose that strong westerlies (0.4 Pa, implying a wind speed of ~ 12 m s-1 at zero degrees centigrade), which were supposedly common during glaciations, can also arrest the leakage. This arrest occurred because the wind stress opposed the momentum flux associated with the retroflection; such an arrest did not require the retroflection to shift in latitude. We use a simple, nonlinear, "reduced gravity" model to show analytically and numerically that, under the above conditions, the eastward wind stress compensates for the zonal westward flow-force associated with the retroflection, thus avoiding the development and shedding of rings. For a nearly zonal wall, westerly winds, and small upper layer thickness along the wall, the arresting wind stress is found, theoretically, to be, τx~0.042α3/2ρf[(2fQ)3/g']1/4 where α is twice the retroflection eddy vorticity, ρ the water density, and Q the Agulhas Current volume flux; the remaining notation is conventional.
Identifier: FSU_migr_coaps_pubs-0053 (IID), 10.1357/002224011799849453 (DOI)
Note: Published in Jounral of Marine Research. This is a pre-published version of the paper. The definitive version is available at the link below.
Citation: Nof, Doron, Zharkov, Volodymyr, Ortiz, Joseph, Paldor, Nathan, Arruda, Wilton, Chassignet, Eric, 2011: The arrested Agulhas retroflection. Journal of Marine Research, Volume 69, Numbers 4-6, July-November 2011 , pp. 659-691(33) http://dx.doi.org/10.1357/002224011799849453
Subject(s): Atmospheric sciences
Meteorology
Oceanography
Persistent Link to This Record: http://purl.flvc.org/fsu/fd/FSU_migr_coaps_pubs-0053
Owner Institution: FSU
Is Part of Series: COAPS Publications.
Is Part Of: Journal of Marine Research.
Issue: 42100, 69

Choose the citation style.
Nof, D., Zharkov, V., Ortiz, J., Paldor, N., Arruda, W., & Chassignet, E. (2011). The arrested Agulhas retroflection. Journal Of Marine Research. Retrieved from http://purl.flvc.org/fsu/fd/FSU_migr_coaps_pubs-0053