Sensitivity of Antarctic Circumpolar Current Transport and Eddy Activity to Wind Patterns in the Southern Ocean
The Southern Hemisphere westerly winds have intensified in recent decades associated with a positive trend in the southern annular mode (SAM). However, the response of the Antarctic Circumpolar Current (ACC) transport and eddy field to wind forcing remains a topic of debate. This study uses global e...
Published in: | Journal of Physical Oceanography |
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ftsouthampton:oai:eprints.soton.ac.uk:377285 2023-08-27T04:05:21+02:00 Sensitivity of Antarctic Circumpolar Current Transport and Eddy Activity to Wind Patterns in the Southern Ocean Langlais, Clothilde E. Rintoul, Stephen R. Zika, Jan D. 2015-04 text https://eprints.soton.ac.uk/377285/ https://eprints.soton.ac.uk/377285/1/jpo-d-14-0053%25252E1.pdf en English eng https://eprints.soton.ac.uk/377285/1/jpo-d-14-0053%25252E1.pdf Langlais, Clothilde E., Rintoul, Stephen R. and Zika, Jan D. (2015) Sensitivity of Antarctic Circumpolar Current Transport and Eddy Activity to Wind Patterns in the Southern Ocean. Journal of Physical Oceanography, 45 (4), 1051-1067. (doi:10.1175/JPO-D-14-0053.1 <http://dx.doi.org/10.1175/JPO-D-14-0053.1>). Article PeerReviewed 2015 ftsouthampton https://doi.org/10.1175/JPO-D-14-0053.1 2023-08-03T22:21:07Z The Southern Hemisphere westerly winds have intensified in recent decades associated with a positive trend in the southern annular mode (SAM). However, the response of the Antarctic Circumpolar Current (ACC) transport and eddy field to wind forcing remains a topic of debate. This study uses global eddy-permitting ocean circulation models driven with both idealized and realistic wind forcing to explore the response to interannual wind strengthening. The response of the barotropic and baroclinic transports and eddy field of the ACC is found to depend on the spatial pattern of the changes in wind forcing. In isolation, an enhancement of the westerlies over the ACC belt leads to an increase of both barotropic and baroclinic transport within the ACC envelope, with lagged enhancement of the eddy kinetic energy (EKE). In contrast, an increase in wind forcing near Antarctica drives a largely barotropic change in transport along closed f/H contours (“free mode”), with little change in eddy activity. Under realistic forcing, the interplay of the SAM and the El Niño–Southern Oscillation (ENSO) influences the spatial distribution of the wind anomalies, in particular the partition between changes in the wind stress over the ACC and along f/H contours. This study finds that the occurrence of a negative or positive ENSO during a positive SAM can cancel or double the wind anomalies near Antarctica, altering the response of the ACC and its eddy field. While a negative ENSO and positive SAM favors an increase in EKE, a positive ENSO and positive SAM lead to barotropic transport changes and no eddy response. Article in Journal/Newspaper Antarc* Antarctic Antarctica Southern Ocean University of Southampton: e-Prints Soton Antarctic Southern Ocean The Antarctic Journal of Physical Oceanography 45 4 1051 1067 |
institution |
Open Polar |
collection |
University of Southampton: e-Prints Soton |
op_collection_id |
ftsouthampton |
language |
English |
description |
The Southern Hemisphere westerly winds have intensified in recent decades associated with a positive trend in the southern annular mode (SAM). However, the response of the Antarctic Circumpolar Current (ACC) transport and eddy field to wind forcing remains a topic of debate. This study uses global eddy-permitting ocean circulation models driven with both idealized and realistic wind forcing to explore the response to interannual wind strengthening. The response of the barotropic and baroclinic transports and eddy field of the ACC is found to depend on the spatial pattern of the changes in wind forcing. In isolation, an enhancement of the westerlies over the ACC belt leads to an increase of both barotropic and baroclinic transport within the ACC envelope, with lagged enhancement of the eddy kinetic energy (EKE). In contrast, an increase in wind forcing near Antarctica drives a largely barotropic change in transport along closed f/H contours (“free mode”), with little change in eddy activity. Under realistic forcing, the interplay of the SAM and the El Niño–Southern Oscillation (ENSO) influences the spatial distribution of the wind anomalies, in particular the partition between changes in the wind stress over the ACC and along f/H contours. This study finds that the occurrence of a negative or positive ENSO during a positive SAM can cancel or double the wind anomalies near Antarctica, altering the response of the ACC and its eddy field. While a negative ENSO and positive SAM favors an increase in EKE, a positive ENSO and positive SAM lead to barotropic transport changes and no eddy response. |
format |
Article in Journal/Newspaper |
author |
Langlais, Clothilde E. Rintoul, Stephen R. Zika, Jan D. |
spellingShingle |
Langlais, Clothilde E. Rintoul, Stephen R. Zika, Jan D. Sensitivity of Antarctic Circumpolar Current Transport and Eddy Activity to Wind Patterns in the Southern Ocean |
author_facet |
Langlais, Clothilde E. Rintoul, Stephen R. Zika, Jan D. |
author_sort |
Langlais, Clothilde E. |
title |
Sensitivity of Antarctic Circumpolar Current Transport and Eddy Activity to Wind Patterns in the Southern Ocean |
title_short |
Sensitivity of Antarctic Circumpolar Current Transport and Eddy Activity to Wind Patterns in the Southern Ocean |
title_full |
Sensitivity of Antarctic Circumpolar Current Transport and Eddy Activity to Wind Patterns in the Southern Ocean |
title_fullStr |
Sensitivity of Antarctic Circumpolar Current Transport and Eddy Activity to Wind Patterns in the Southern Ocean |
title_full_unstemmed |
Sensitivity of Antarctic Circumpolar Current Transport and Eddy Activity to Wind Patterns in the Southern Ocean |
title_sort |
sensitivity of antarctic circumpolar current transport and eddy activity to wind patterns in the southern ocean |
publishDate |
2015 |
url |
https://eprints.soton.ac.uk/377285/ https://eprints.soton.ac.uk/377285/1/jpo-d-14-0053%25252E1.pdf |
geographic |
Antarctic Southern Ocean The Antarctic |
geographic_facet |
Antarctic Southern Ocean The Antarctic |
genre |
Antarc* Antarctic Antarctica Southern Ocean |
genre_facet |
Antarc* Antarctic Antarctica Southern Ocean |
op_relation |
https://eprints.soton.ac.uk/377285/1/jpo-d-14-0053%25252E1.pdf Langlais, Clothilde E., Rintoul, Stephen R. and Zika, Jan D. (2015) Sensitivity of Antarctic Circumpolar Current Transport and Eddy Activity to Wind Patterns in the Southern Ocean. Journal of Physical Oceanography, 45 (4), 1051-1067. (doi:10.1175/JPO-D-14-0053.1 <http://dx.doi.org/10.1175/JPO-D-14-0053.1>). |
op_doi |
https://doi.org/10.1175/JPO-D-14-0053.1 |
container_title |
Journal of Physical Oceanography |
container_volume |
45 |
container_issue |
4 |
container_start_page |
1051 |
op_container_end_page |
1067 |
_version_ |
1775357026287747072 |