Turbulence in Antarctic Circumpolar Current standing meanders

Lead Research Organisation: University of Southampton
Department Name: School of Ocean and Earth Science

Abstract

This proposal is to study the role of turbulent mixing in the meridional overturning circulation of the Southern Ocean and the dynamics of the Antarctic Circumpolar Current (ACC). The project is motivated by the recent discovery of Southern Ocean regions of remarkably intense and widespread turbulence, an observation that defies current theoretical understanding of the circulation based on the assumption of little mixing in the ocean interior. The project is exciting because it will use innovative instrumentation to measure turbulent mixing in the deep Southern Ocean for the first time, to determine its causes and to assess its impact on the overturning circulation and the transport of the ACC. The focus of the project will be on observing and modelling the circulation and mixing in a standing meander of the ACC north of the Kerguelen Plateau, a dynamically important region of the current system. This novel way of looking at the ACC will provide important new insight into how the the current interacts with bottom topography (a crucial issue for understanding what sets the ACC transport), the dynamical nature of the overturning circulation of the Southern Ocean and how this should be represented in ocean circulation and climate models.

Publications

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Naveira Garabato A (2011) Eddy stirring in the Southern Ocean in Journal of Geophysical Research

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Naveira Garabato A (2013) Internal Waves and Turbulence in the Antarctic Circumpolar Current in Journal of Physical Oceanography

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Palmer M (2012) Water mass pathways and transports over the South Scotia Ridge west of 50°W in Deep Sea Research Part I: Oceanographic Research Papers

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Trossman D (2015) Internal lee wave closures: Parameter sensitivity and comparison to observations in Journal of Geophysical Research: Oceans

 
Description The SOFINE project has discovered the following important issues:



* The Antarctic Circumpolar Current (ACC) jets are commonly impermeable to isopycnal mixing by mesoscale eddies, but they become leaky under certain conditions when they interact with large-scale topography.



* The ACC jets drive an intensification in deep-ocean turbulence and diapycnal mixing when they impinge on small-scale bottom topography, via the generation and breaking of internal waves.



* The ACC often suppresses the breaking of internal waves, likely via a mechanism involving wave - mean flow interactions.
Exploitation Route The findings on mixing above are providing a benchmark for the improvement of representations of oceanic turbulence in climate-scale ocean models.
Sectors Environment

 
Description The findings on mixing above are providing a benchmark for the improvement of representations of oceanic turbulence in climate-scale ocean models.
First Year Of Impact 2013
Sector Other