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Observations of a diapycnal shortcut to adiabatic upwelling of Antarctic Circumpolar Deep Water

Lookup NU author(s): Dr Miguel Morales MaquedaORCiD

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Abstract

In the Southern Ocean, small-scale turbulence causes diapycnal mixing which influences important water mass transformations, in turn impacting large-scale ocean transports such as the Meridional Overturning trculation (MOC), a key controller of Earth's climate. We present direct observations of mixing over the Antarctic continental slope between water masses that are part of the Southern Ocean MOC. A 12 h time series of microstructure turbulence measurements, hydrography, and velocity observations off Elephant Island, north of the Antarctic Peninsula, reveals two concurrent bursts of elevated dissipation of O(10−6) W kg−1, resulting in heat fluxes ∼10 times higher than basin-integrated Drake Passage estimates. This occurs across the boundary between adjacent adiabatic upwelling and downwelling overturning cells. Ray tracing to nearby topography shows mixing between 300 and 400 m is consistent with the breaking of locally generated internal tidal waves. Since similar conditions extend to much of the Antarctic continental slope where these water masses outcrop, diapycnal mixing may contribute significantly to upwelling.


Publication metadata

Author(s): Mead Silvester J, Lenn YD, Polton JA, Rippeth TP, Morales Maqueda MA

Publication type: Article

Publication status: Published

Journal: Geophysical Research Letter

Year: 2014

Volume: 41

Issue: 22

Pages: 7950-7956

Print publication date: 12/12/2014

Online publication date: 22/10/2014

Acceptance date: 20/10/2014

ISSN (print): 0094-8276

ISSN (electronic): 1944-8007

Publisher: American Geophysical Union

URL: http://dx.doi.org/10.1002/2014GL061538/full

DOI: 10.1002/2014GL061538


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