The University of Southampton
University of Southampton Institutional Repository

Mechanisms of eddy dissipation in the Southern Ocean

Mechanisms of eddy dissipation in the Southern Ocean
Mechanisms of eddy dissipation in the Southern Ocean
The Southern Ocean is a region of fast currents, energetic eddies, large amplitude internal waves and strong turbulence. It is also a place where substantial quantities of heat and carbon are exchanged between the ocean and atmosphere. Our ability to predict global climatic changes relies, in part, on understanding the physical processes occurring there.

This thesis adds to the growing body of knowledge about Southern Ocean dynamics by using in-situ observations from profiling floats to study a lee wave generated in the Drake Passage by the flow of the Antarctic Circumpolar Current over topography. It is the first unambiguous example of such a wave in the Southern Ocean and is found to be associated with large fluxes of energy and momentum, as well as elevated turbulent dissipation. A key finding is that the energy flux is two orders of magnitude larger than the depth integrated dissipation, indicating that the majority of the energy may not be dissipated locally.

The wave observation was made possible by developing a method for measuring vertical velo- city from profiling floats. The essence of the method is to model the expected steady motion of the float and subtract this from the observed motion to retrieve the vertical velocity. It is easily applicable to many similar floats and has the potential to provide a global picture of vertical flows in the ocean.

The interaction of eddies and internal waves away from boundaries is investigated for the first time in the Southern Ocean using data from a mooring array in the Scotia Sea. Theoretical arguments are made to treat the interaction as a viscous coupling between internal wave stress and eddy strain. The results imply that eddy dissipation by interaction with the internal wave field is an important energy sink and comparable in magnitude to lee wave generation and bottom boundary layer viscous processes.
University of Southampton
Cusack, Jesse
637e34b0-29b7-43be-8290-51648580db8b
Cusack, Jesse
637e34b0-29b7-43be-8290-51648580db8b
Naveira Garabato, Alberto
97c0e923-f076-4b38-b89b-938e11cea7a6

Cusack, Jesse (2017) Mechanisms of eddy dissipation in the Southern Ocean. University of Southampton, Doctoral Thesis, 112pp.

Record type: Thesis (Doctoral)

Abstract

The Southern Ocean is a region of fast currents, energetic eddies, large amplitude internal waves and strong turbulence. It is also a place where substantial quantities of heat and carbon are exchanged between the ocean and atmosphere. Our ability to predict global climatic changes relies, in part, on understanding the physical processes occurring there.

This thesis adds to the growing body of knowledge about Southern Ocean dynamics by using in-situ observations from profiling floats to study a lee wave generated in the Drake Passage by the flow of the Antarctic Circumpolar Current over topography. It is the first unambiguous example of such a wave in the Southern Ocean and is found to be associated with large fluxes of energy and momentum, as well as elevated turbulent dissipation. A key finding is that the energy flux is two orders of magnitude larger than the depth integrated dissipation, indicating that the majority of the energy may not be dissipated locally.

The wave observation was made possible by developing a method for measuring vertical velo- city from profiling floats. The essence of the method is to model the expected steady motion of the float and subtract this from the observed motion to retrieve the vertical velocity. It is easily applicable to many similar floats and has the potential to provide a global picture of vertical flows in the ocean.

The interaction of eddies and internal waves away from boundaries is investigated for the first time in the Southern Ocean using data from a mooring array in the Scotia Sea. Theoretical arguments are made to treat the interaction as a viscous coupling between internal wave stress and eddy strain. The results imply that eddy dissipation by interaction with the internal wave field is an important energy sink and comparable in magnitude to lee wave generation and bottom boundary layer viscous processes.

Text
Cusack, Jesse_PhD_Thesis_Jan_18 - Version of Record
Available under License University of Southampton Thesis Licence.
Download (15MB)

More information

Published date: 18 December 2017

Identifiers

Local EPrints ID: 417983
URI: http://eprints.soton.ac.uk/id/eprint/417983
PURE UUID: 7aaddf2a-7025-4ec6-ad76-e96aa6f8c30e
ORCID for Jesse Cusack: ORCID iD orcid.org/0000-0003-2065-4397

Catalogue record

Date deposited: 20 Feb 2018 17:30
Last modified: 11 Dec 2021 23:14

Export record

Contributors

Author: Jesse Cusack ORCID iD
Thesis advisor: Alberto Naveira Garabato

Download statistics

Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.

View more statistics

Atom RSS 1.0 RSS 2.0

Contact ePrints Soton: eprints@soton.ac.uk

ePrints Soton supports OAI 2.0 with a base URL of http://eprints.soton.ac.uk/cgi/oai2

This repository has been built using EPrints software, developed at the University of Southampton, but available to everyone to use.

We use cookies to ensure that we give you the best experience on our website. If you continue without changing your settings, we will assume that you are happy to receive cookies on the University of Southampton website.

×