A microscale view of mixing and overturning across the Antarctic Circumpolar Current

(Naveira Garabato, Alberto C. and Polzin, Kurt L. and Ferrari, Raffaele and Zika, Jan D. and Forryan, Alexander), Journal of Physical Oceanography, vol. 46, pp. pages, 2016.

Abstract

AbstractThe 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 analysing 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 order of magnitude suppression of isoneutral stirring in the upper kilometre of the ACC frontal jets, and an order-of-magnitude intensification of dianeutral stirring in the sub-pycnocline and deepest layers of the ACC. These variations balance an overturning circulation with meridional …

doi = 10.1175/JPO-D-15-0025.1

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