Lagrangian study of the Southern Ocean circulation
The Southern Ocean is an important region for the sequestration of heat, carbon dioxide and other tracers. The Southern Ocean circulation is typically described in a circumpolarly averaged sense as a Meridional Overturning Circulation (MOC), but the detailed 3-D pathways that make up this circulatio...
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St. Edmund's College
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ftunivcam:oai:www.repository.cam.ac.uk:1810/288743 2023-07-30T03:58:27+02:00 Lagrangian study of the Southern Ocean circulation McAufield, Ewa Katarzyna 2019-02-02T21:49:01Z application/pdf https://doi.org/10.17863/CAM.36004 https://www.repository.cam.ac.uk/handle/1810/288743 en eng St. Edmund's College DAMTP University of Cambridge doi:10.17863/CAM.36004 https://www.repository.cam.ac.uk/handle/1810/288743 All Rights Reserved https://www.rioxx.net/licenses/all-rights-reserved/ Lagrangian particles three dimensional pathways Southern Ocean circulation Lagrangian diffusivity Thesis Doctoral Doctor of Philosophy (PhD) PhD in Applied Mathematics and Theoretical Physics 2019 ftunivcam https://doi.org/10.17863/CAM.36004 2023-07-10T21:14:11Z The Southern Ocean is an important region for the sequestration of heat, carbon dioxide and other tracers. The Southern Ocean circulation is typically described in a circumpolarly averaged sense as a Meridional Overturning Circulation (MOC), but the detailed 3-D pathways that make up this circulation remain poorly understood. We use Lagrangian particle trajectories, obtained from eddy permitting numerical models, to map out and quantify different aspects of the 3-D circulation. We first introduce various definitions used to quantify efficient export from the Antarctic Circumpolar Current (ACC) to the subtropical gyres. Using these definitions, we show that the permanent northward export varies by water mass and occurs in localised regions; with 11 key pathways identified. We then examine the dynamics setting the location and efficiency of the identified pathways, which includes the investigation of the role of diapycnal mixing and the impact of short and long time variability in the flow. Although we show that the flow of particles in the 3-D model is predominantly isopycnal, we find that particles that are forced to remain on isopycnals lead to approx. 60% lower export (mainly via three pathways) than identical releases where the diapycnal component of advection is included. Enhanced upward mixing near rough topography, and downward mixing in the southeast Pacific, were shown to be mostly responsible for the export. In addition, we show that most of the export pathways are mainly influenced by timescales from 90 days to 20 years, which suggests that mesoscale eddies are not the leading-order importance in the northward export from the ACC to the subtropical gyres. However, we also find that mesoscale eddies and the mean-ACC flow play a significant role in setting the export from the ACC in some pathways. These results highlight the role of temporal variability and vertical transport in enhancing the northward flow from the ACC by allowing transport across barotropic streamlines and onto more efficiently ... Doctoral or Postdoctoral Thesis Antarc* Antarctic Southern Ocean Apollo - University of Cambridge Repository Antarctic Pacific Southern Ocean The Antarctic |
institution |
Open Polar |
collection |
Apollo - University of Cambridge Repository |
op_collection_id |
ftunivcam |
language |
English |
topic |
Lagrangian particles three dimensional pathways Southern Ocean circulation Lagrangian diffusivity |
spellingShingle |
Lagrangian particles three dimensional pathways Southern Ocean circulation Lagrangian diffusivity McAufield, Ewa Katarzyna Lagrangian study of the Southern Ocean circulation |
topic_facet |
Lagrangian particles three dimensional pathways Southern Ocean circulation Lagrangian diffusivity |
description |
The Southern Ocean is an important region for the sequestration of heat, carbon dioxide and other tracers. The Southern Ocean circulation is typically described in a circumpolarly averaged sense as a Meridional Overturning Circulation (MOC), but the detailed 3-D pathways that make up this circulation remain poorly understood. We use Lagrangian particle trajectories, obtained from eddy permitting numerical models, to map out and quantify different aspects of the 3-D circulation. We first introduce various definitions used to quantify efficient export from the Antarctic Circumpolar Current (ACC) to the subtropical gyres. Using these definitions, we show that the permanent northward export varies by water mass and occurs in localised regions; with 11 key pathways identified. We then examine the dynamics setting the location and efficiency of the identified pathways, which includes the investigation of the role of diapycnal mixing and the impact of short and long time variability in the flow. Although we show that the flow of particles in the 3-D model is predominantly isopycnal, we find that particles that are forced to remain on isopycnals lead to approx. 60% lower export (mainly via three pathways) than identical releases where the diapycnal component of advection is included. Enhanced upward mixing near rough topography, and downward mixing in the southeast Pacific, were shown to be mostly responsible for the export. In addition, we show that most of the export pathways are mainly influenced by timescales from 90 days to 20 years, which suggests that mesoscale eddies are not the leading-order importance in the northward export from the ACC to the subtropical gyres. However, we also find that mesoscale eddies and the mean-ACC flow play a significant role in setting the export from the ACC in some pathways. These results highlight the role of temporal variability and vertical transport in enhancing the northward flow from the ACC by allowing transport across barotropic streamlines and onto more efficiently ... |
format |
Doctoral or Postdoctoral Thesis |
author |
McAufield, Ewa Katarzyna |
author_facet |
McAufield, Ewa Katarzyna |
author_sort |
McAufield, Ewa Katarzyna |
title |
Lagrangian study of the Southern Ocean circulation |
title_short |
Lagrangian study of the Southern Ocean circulation |
title_full |
Lagrangian study of the Southern Ocean circulation |
title_fullStr |
Lagrangian study of the Southern Ocean circulation |
title_full_unstemmed |
Lagrangian study of the Southern Ocean circulation |
title_sort |
lagrangian study of the southern ocean circulation |
publisher |
St. Edmund's College |
publishDate |
2019 |
url |
https://doi.org/10.17863/CAM.36004 https://www.repository.cam.ac.uk/handle/1810/288743 |
geographic |
Antarctic Pacific Southern Ocean The Antarctic |
geographic_facet |
Antarctic Pacific Southern Ocean The Antarctic |
genre |
Antarc* Antarctic Southern Ocean |
genre_facet |
Antarc* Antarctic Southern Ocean |
op_relation |
doi:10.17863/CAM.36004 https://www.repository.cam.ac.uk/handle/1810/288743 |
op_rights |
All Rights Reserved https://www.rioxx.net/licenses/all-rights-reserved/ |
op_doi |
https://doi.org/10.17863/CAM.36004 |
_version_ |
1772821239715332096 |