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Turbulent mixing produced by breaking of internal waves plays an important role in setting the patterns of downwelling and upwelling of deep dense waters and thereby helps sustain the global deep ocean overturning circulation. A key parameter used to characterize turbulent mixing is its efficiency, defined here as the fraction of the energy available to turbulence that is invested in mixing. Efficiency is conventionally approximated by a constant value near one sixth. Here we show that efficiency varies significantly in the abyssal ocean and can be as large as approximately one third in density stratified regions near topographic features. Our results indicate that variations in efficiency exert a first-order control over the rate of overturning of the lower branch of the meridional overturning circulation.

Item Type:	Refereed Article
Keywords:	ocean mixing, mixing efficiency, ocean overturning circulation, water-mass transformation
Research Division:	Earth Sciences
Research Group:	Oceanography
Research Field:	Physical oceanography
Objective Division:	Environmental Policy, Climate Change and Natural Hazards
Objective Group:	Understanding climate change
Objective Field:	Climate change models
UTAS Author:	Nikurashin, M (Dr Maxim Nikurashin)
ID Code:	117223
Year Published:	2017
Funding Support:	Australian Research Council (DE150100937)
Web of Science® Times Cited:	58
Deposited By:	Oceans and Cryosphere
Deposited On:	2017-06-05
Last Modified:	2018-05-24
Downloads:	138 View Download Statistics