A Microscale View of Mixing and Overturning across the Antarctic Circumpolar Current
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Author(s)
Naveira Garabato, Alberto C.
Polzin, Kurt L.
Ferrari, Raffaele
Zika, Jan D.
Forryan, Alexander
Date Issued
January 2016
Journal
Journal of Physical Oceanography
Publisher
American Meteorological Society
Citation
Naveira Garabato, Alberto C.; Polzin, Kurt L.; Ferrari, Raffaele; Zika, Jan D. and Forryan, Alexander. “A Microscale View of Mixing and Overturning Across the Antarctic Circumpolar Current.” Journal of Physical Oceanography 46, no. 1 (January 2016): 233–254. © American Meteorological Society
Version
Final published version
Abstract
The relative roles of isoneutral stirring by mesoscale eddies and dianeutral stirring by small-scale turbulence in setting the large-scale temperature–salinity relation of the Southern Ocean against the action of the overturning circulation are assessed by analyzing a set of shear and temperature microstructure measurements across Drake Passage in a “triple decomposition” framework. It is shown that a picture of mixing and overturning across a region of the Antarctic Circumpolar Current (ACC) may be constructed from a relatively modest number of microstructure profiles. The rates of isoneutral and dianeutral stirring are found to exhibit distinct, characteristic, and abrupt variations: most notably, a one to two orders of magnitude suppression of isoneutral stirring in the upper kilometer of the ACC frontal jets and an order of magnitude intensification of dianeutral stirring in the subpycnocline and deepest layers of the ACC. These variations balance an overturning circulation with meridional flows of O(1) mm s⁻¹ across the ACC’s mean thermohaline structure. Isoneutral and dianeutral stirring play complementary roles in balancing the overturning, with isoneutral processes dominating in intermediate waters and the Upper Circumpolar Deep Water and dianeutral processes prevailing in lighter and denser layers.
MIT Department
Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences
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Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use.
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DOI of Published Version
https://doi.org/10.1175/jpo-d-15-0025.1
