Forced and intrinsic variability in the response to increased wind stress of an idealized Southern Ocean
We use ensemble runs of a three-layer, quasigeostrophic idealized Southern Ocean model to explore the roles of forced and intrinsic variability in response to a linear increase of wind stress imposed over a 30-year period. We find no increase of eastward circumpolar volume transport in response to t...
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ftnerc:oai:nora.nerc.ac.uk:508651 2023-05-15T18:24:52+02:00 Forced and intrinsic variability in the response to increased wind stress of an idealized Southern Ocean Wilson, Chris Hughes, Christopher W. Blundell, Jeffrey R. 2015-01 text http://nora.nerc.ac.uk/id/eprint/508651/ https://nora.nerc.ac.uk/id/eprint/508651/1/Wilson_et_al-2015-Journal_of_Geophysical_Research__Oceans.pdf en eng https://nora.nerc.ac.uk/id/eprint/508651/1/Wilson_et_al-2015-Journal_of_Geophysical_Research__Oceans.pdf Wilson, Chris orcid:0000-0003-0891-2912 Hughes, Christopher W. orcid:0000-0002-9355-0233 Blundell, Jeffrey R. 2015 Forced and intrinsic variability in the response to increased wind stress of an idealized Southern Ocean. Journal of Geophysical Research: Oceans, 120 (1). 113-130. https://doi.org/10.1002/2014JC010315 <https://doi.org/10.1002/2014JC010315> cc_by_4 CC-BY Publication - Article PeerReviewed 2015 ftnerc https://doi.org/10.1002/2014JC010315 2023-02-04T19:40:27Z We use ensemble runs of a three-layer, quasigeostrophic idealized Southern Ocean model to explore the roles of forced and intrinsic variability in response to a linear increase of wind stress imposed over a 30-year period. We find no increase of eastward circumpolar volume transport in response to the increased wind stress. A large part of the resulting time series can be explained by a response in which the eddy kinetic energy is linearly proportional to the wind stress with a possible time lag, but no statistically significant lag is found. However, this simple relationship is not the whole story: several intrinsic timescales also influence the response. We find an e-folding timescale for growth of small perturbations of 1-2 weeks. The energy budget for intrinsic variability at periods shorter than a year is dominated by exchange between kinetic and potential energy. At longer timescales, we find an intrinsic mode with period in the region of 15 years, which is dominated by changes in potential energy and frictional dissipation in a manner consistent with that seen by Hogg and Blundell [2006]. A similar mode influences the response to changing wind stress. This influence, robust to perturbations, is different from the supposed linear relationship between wind stress and eddy kinetic energy, and persists for 5-10 years in this model, suggestive of a forced oscillatory mode with period of around 15 years. If present in the real ocean, such a mode would imply a degree of predictability of Southern Ocean dynamics on multi-year timescales. Article in Journal/Newspaper Southern Ocean Natural Environment Research Council: NERC Open Research Archive Southern Ocean Blundell ENVELOPE(76.111,76.111,-69.427,-69.427) Journal of Geophysical Research: Oceans 120 1 113 130 |
institution |
Open Polar |
collection |
Natural Environment Research Council: NERC Open Research Archive |
op_collection_id |
ftnerc |
language |
English |
description |
We use ensemble runs of a three-layer, quasigeostrophic idealized Southern Ocean model to explore the roles of forced and intrinsic variability in response to a linear increase of wind stress imposed over a 30-year period. We find no increase of eastward circumpolar volume transport in response to the increased wind stress. A large part of the resulting time series can be explained by a response in which the eddy kinetic energy is linearly proportional to the wind stress with a possible time lag, but no statistically significant lag is found. However, this simple relationship is not the whole story: several intrinsic timescales also influence the response. We find an e-folding timescale for growth of small perturbations of 1-2 weeks. The energy budget for intrinsic variability at periods shorter than a year is dominated by exchange between kinetic and potential energy. At longer timescales, we find an intrinsic mode with period in the region of 15 years, which is dominated by changes in potential energy and frictional dissipation in a manner consistent with that seen by Hogg and Blundell [2006]. A similar mode influences the response to changing wind stress. This influence, robust to perturbations, is different from the supposed linear relationship between wind stress and eddy kinetic energy, and persists for 5-10 years in this model, suggestive of a forced oscillatory mode with period of around 15 years. If present in the real ocean, such a mode would imply a degree of predictability of Southern Ocean dynamics on multi-year timescales. |
format |
Article in Journal/Newspaper |
author |
Wilson, Chris Hughes, Christopher W. Blundell, Jeffrey R. |
spellingShingle |
Wilson, Chris Hughes, Christopher W. Blundell, Jeffrey R. Forced and intrinsic variability in the response to increased wind stress of an idealized Southern Ocean |
author_facet |
Wilson, Chris Hughes, Christopher W. Blundell, Jeffrey R. |
author_sort |
Wilson, Chris |
title |
Forced and intrinsic variability in the response to increased wind stress of an idealized Southern Ocean |
title_short |
Forced and intrinsic variability in the response to increased wind stress of an idealized Southern Ocean |
title_full |
Forced and intrinsic variability in the response to increased wind stress of an idealized Southern Ocean |
title_fullStr |
Forced and intrinsic variability in the response to increased wind stress of an idealized Southern Ocean |
title_full_unstemmed |
Forced and intrinsic variability in the response to increased wind stress of an idealized Southern Ocean |
title_sort |
forced and intrinsic variability in the response to increased wind stress of an idealized southern ocean |
publishDate |
2015 |
url |
http://nora.nerc.ac.uk/id/eprint/508651/ https://nora.nerc.ac.uk/id/eprint/508651/1/Wilson_et_al-2015-Journal_of_Geophysical_Research__Oceans.pdf |
long_lat |
ENVELOPE(76.111,76.111,-69.427,-69.427) |
geographic |
Southern Ocean Blundell |
geographic_facet |
Southern Ocean Blundell |
genre |
Southern Ocean |
genre_facet |
Southern Ocean |
op_relation |
https://nora.nerc.ac.uk/id/eprint/508651/1/Wilson_et_al-2015-Journal_of_Geophysical_Research__Oceans.pdf Wilson, Chris orcid:0000-0003-0891-2912 Hughes, Christopher W. orcid:0000-0002-9355-0233 Blundell, Jeffrey R. 2015 Forced and intrinsic variability in the response to increased wind stress of an idealized Southern Ocean. Journal of Geophysical Research: Oceans, 120 (1). 113-130. https://doi.org/10.1002/2014JC010315 <https://doi.org/10.1002/2014JC010315> |
op_rights |
cc_by_4 |
op_rightsnorm |
CC-BY |
op_doi |
https://doi.org/10.1002/2014JC010315 |
container_title |
Journal of Geophysical Research: Oceans |
container_volume |
120 |
container_issue |
1 |
container_start_page |
113 |
op_container_end_page |
130 |
_version_ |
1766205849679691776 |