Topographic enhancement of Eddy efficiency in baroclinic equilibration
The processes that determine the depth of the Southern Ocean thermocline are considered. In existing conceptual frameworks, the thermocline depth is determined by competition between the mean and eddy heat transport, with a contribution from the interaction with the stratification in the enclosed po...
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ftcdlib:oai:escholarship.org/ark:/13030/qt42n1d9zw 2023-05-15T18:25:27+02:00 Topographic enhancement of Eddy efficiency in baroclinic equilibration Abernathey, R Cessi, P 2107 - 2126 2014-01-01 application/pdf https://escholarship.org/uc/item/42n1d9zw unknown eScholarship, University of California qt42n1d9zw https://escholarship.org/uc/item/42n1d9zw public Journal of Physical Oceanography, vol 44, iss 8 Oceanography Maritime Engineering article 2014 ftcdlib 2020-03-20T23:55:34Z The processes that determine the depth of the Southern Ocean thermocline are considered. In existing conceptual frameworks, the thermocline depth is determined by competition between the mean and eddy heat transport, with a contribution from the interaction with the stratification in the enclosed portion of the ocean. Using numerical simulations, this study examines the equilibration of an idealized circumpolar current with and without topography. The authors find that eddies are much more efficient when topography is present, leading to a shallower thermocline than in the flat case. A simple quasigeostrophic analytical model shows that the topographically induced standing wave increases the effective eddy diffusivity by increasing the local buoyancy gradients and lengthening the buoyancy contours across which the eddies transport heat. In addition to this local heat flux intensification, transient eddy heat fluxes are suppressed away from the topography, especially upstream, indicating that localized topography leads to local (absolute) baroclinic instability and its subsequent finite-amplitude equilibration, which extracts available potential energy very efficiently from the time-mean flow. © 2014 American Meteorological Society. Article in Journal/Newspaper Southern Ocean University of California: eScholarship Southern Ocean |
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University of California: eScholarship |
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language |
unknown |
topic |
Oceanography Maritime Engineering |
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Oceanography Maritime Engineering Abernathey, R Cessi, P Topographic enhancement of Eddy efficiency in baroclinic equilibration |
topic_facet |
Oceanography Maritime Engineering |
description |
The processes that determine the depth of the Southern Ocean thermocline are considered. In existing conceptual frameworks, the thermocline depth is determined by competition between the mean and eddy heat transport, with a contribution from the interaction with the stratification in the enclosed portion of the ocean. Using numerical simulations, this study examines the equilibration of an idealized circumpolar current with and without topography. The authors find that eddies are much more efficient when topography is present, leading to a shallower thermocline than in the flat case. A simple quasigeostrophic analytical model shows that the topographically induced standing wave increases the effective eddy diffusivity by increasing the local buoyancy gradients and lengthening the buoyancy contours across which the eddies transport heat. In addition to this local heat flux intensification, transient eddy heat fluxes are suppressed away from the topography, especially upstream, indicating that localized topography leads to local (absolute) baroclinic instability and its subsequent finite-amplitude equilibration, which extracts available potential energy very efficiently from the time-mean flow. © 2014 American Meteorological Society. |
format |
Article in Journal/Newspaper |
author |
Abernathey, R Cessi, P |
author_facet |
Abernathey, R Cessi, P |
author_sort |
Abernathey, R |
title |
Topographic enhancement of Eddy efficiency in baroclinic equilibration |
title_short |
Topographic enhancement of Eddy efficiency in baroclinic equilibration |
title_full |
Topographic enhancement of Eddy efficiency in baroclinic equilibration |
title_fullStr |
Topographic enhancement of Eddy efficiency in baroclinic equilibration |
title_full_unstemmed |
Topographic enhancement of Eddy efficiency in baroclinic equilibration |
title_sort |
topographic enhancement of eddy efficiency in baroclinic equilibration |
publisher |
eScholarship, University of California |
publishDate |
2014 |
url |
https://escholarship.org/uc/item/42n1d9zw |
op_coverage |
2107 - 2126 |
geographic |
Southern Ocean |
geographic_facet |
Southern Ocean |
genre |
Southern Ocean |
genre_facet |
Southern Ocean |
op_source |
Journal of Physical Oceanography, vol 44, iss 8 |
op_relation |
qt42n1d9zw https://escholarship.org/uc/item/42n1d9zw |
op_rights |
public |
_version_ |
1766206906924269568 |