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

Mead Silvester, J.; Lenn, Yueng-Djern; Polton, Jeff A.; Rippeth, Tom P.; Morales Maqueda, M.. 2014 Observations of a diapycnal shortcut to adiabatic upwelling of Antarctic Circumpolar Deep Water. Geophysical Research Letters, 41 (22). 7950-7956. https://doi.org/10.1002/2014GL061538

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Abstract/Summary

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 Circulation (MOC), a key controller of Earth'sclimate. We present direct observations of mixing over the Antarctic continental slope between water masses that are part of the Southern Ocean MOC. A 12-hour 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(10–6Wkg–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 and topography show mixing between 300-400 m 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, their transformation may contribute significantly to upwelling.

Item Type: Publication - Article
Digital Object Identifier (DOI): https://doi.org/10.1002/2014GL061538
ISSN: 00948276
Additional Keywords: dissipation; diapycnal mixing; adiabatic upwelling; meridional overturning circulation; southern ocean; internal tide
Date made live: 12 Nov 2014 16:09 +0 (UTC)
URI: http://nora.nerc.ac.uk/id/eprint/508796

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