Jet Instability over Smooth, Corrugated, and Realistic Bathymetry
The stability of a horizontally and vertically sheared surface jet is examined, with a focus on the vertical structure of the resultant eddies. Over a flat bottom, the instability is mixed baroclinic/barotropic, producing strong eddies at depth that are characteristically shifted downstream relative...
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ftoslouniv:oai:www.duo.uio.no:10852/76718 2023-05-15T13:57:09+02:00 Jet Instability over Smooth, Corrugated, and Realistic Bathymetry Lacasce, Joseph Henry Escartin, Javier Chassignet, Eric P. Xu, Xiaobiao 2019-06-19T16:53:15Z http://hdl.handle.net/10852/76718 http://urn.nb.no/URN:NBN:no-79800 https://doi.org/10.1175/JPO-D-18-0129.1 EN eng http://urn.nb.no/URN:NBN:no-79800 Lacasce, Joseph Henry Escartin, Javier Chassignet, Eric P. Xu, Xiaobiao . Jet Instability over Smooth, Corrugated, and Realistic Bathymetry. Journal of Physical Oceanography. 2019, 49(2), 585-605 http://hdl.handle.net/10852/76718 1706202 info:ofi/fmt:kev:mtx:ctx&ctx_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:journal&rft.jtitle=Journal of Physical Oceanography&rft.volume=49&rft.spage=585&rft.date=2019 Journal of Physical Oceanography 49 2 585 605 https://doi.org/10.1175/JPO-D-18-0129.1 URN:NBN:no-79800 Fulltext https://www.duo.uio.no/bitstream/handle/10852/76718/2/lacasce_jpo19.pdf 0022-3670 Journal article Tidsskriftartikkel Peer reviewed PublishedVersion 2019 ftoslouniv https://doi.org/10.1175/JPO-D-18-0129.1 2020-06-21T08:54:36Z The stability of a horizontally and vertically sheared surface jet is examined, with a focus on the vertical structure of the resultant eddies. Over a flat bottom, the instability is mixed baroclinic/barotropic, producing strong eddies at depth that are characteristically shifted downstream relative to the surface eddies. Baroclinic instability is suppressed over a large slope for retrograde jets (with a flow antiparallel to topographic wave propagation) and to a lesser extent for prograde jets (with flow parallel to topographic wave propagation), as seen previously. In such cases, barotropic (lateral) instability dominates if the jet is sufficiently narrow. This yields surface eddies whose size is independent of the slope but proportional to the jet width. Deep eddies still form, forced by interfacial motion associated with the surface eddies, but they are weaker than under baroclinic instability and are vertically aligned with the surface eddies. A sinusoidal ridge acts similarly, suppressing baroclinic instability and favoring lateral instability in the upper layer. A ridge with a 1-km wavelength and an amplitude of roughly 10 m is sufficient to suppress baroclinic instability. Surveys of bottom roughness from bathymetry acquired with shipboard multibeam echo sounding reveal that such heights are common beneath the Kuroshio, the Antarctic Circumpolar Current, and, to a lesser extent, the Gulf Stream. Consistent with this, vorticity and velocity cross sections from a 1/50° HYCOM simulation suggest that Gulf Stream eddies are vertically aligned, as in the linear stability calculations with strong topography. Thus, lateral instability may be more common than previously thought, owing to topography hindering vertical energy transfer. Article in Journal/Newspaper Antarc* Antarctic Universitet i Oslo: Digitale utgivelser ved UiO (DUO) Antarctic The Antarctic Journal of Physical Oceanography 49 2 585 605 |
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Open Polar |
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Universitet i Oslo: Digitale utgivelser ved UiO (DUO) |
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ftoslouniv |
language |
English |
description |
The stability of a horizontally and vertically sheared surface jet is examined, with a focus on the vertical structure of the resultant eddies. Over a flat bottom, the instability is mixed baroclinic/barotropic, producing strong eddies at depth that are characteristically shifted downstream relative to the surface eddies. Baroclinic instability is suppressed over a large slope for retrograde jets (with a flow antiparallel to topographic wave propagation) and to a lesser extent for prograde jets (with flow parallel to topographic wave propagation), as seen previously. In such cases, barotropic (lateral) instability dominates if the jet is sufficiently narrow. This yields surface eddies whose size is independent of the slope but proportional to the jet width. Deep eddies still form, forced by interfacial motion associated with the surface eddies, but they are weaker than under baroclinic instability and are vertically aligned with the surface eddies. A sinusoidal ridge acts similarly, suppressing baroclinic instability and favoring lateral instability in the upper layer. A ridge with a 1-km wavelength and an amplitude of roughly 10 m is sufficient to suppress baroclinic instability. Surveys of bottom roughness from bathymetry acquired with shipboard multibeam echo sounding reveal that such heights are common beneath the Kuroshio, the Antarctic Circumpolar Current, and, to a lesser extent, the Gulf Stream. Consistent with this, vorticity and velocity cross sections from a 1/50° HYCOM simulation suggest that Gulf Stream eddies are vertically aligned, as in the linear stability calculations with strong topography. Thus, lateral instability may be more common than previously thought, owing to topography hindering vertical energy transfer. |
format |
Article in Journal/Newspaper |
author |
Lacasce, Joseph Henry Escartin, Javier Chassignet, Eric P. Xu, Xiaobiao |
spellingShingle |
Lacasce, Joseph Henry Escartin, Javier Chassignet, Eric P. Xu, Xiaobiao Jet Instability over Smooth, Corrugated, and Realistic Bathymetry |
author_facet |
Lacasce, Joseph Henry Escartin, Javier Chassignet, Eric P. Xu, Xiaobiao |
author_sort |
Lacasce, Joseph Henry |
title |
Jet Instability over Smooth, Corrugated, and Realistic Bathymetry |
title_short |
Jet Instability over Smooth, Corrugated, and Realistic Bathymetry |
title_full |
Jet Instability over Smooth, Corrugated, and Realistic Bathymetry |
title_fullStr |
Jet Instability over Smooth, Corrugated, and Realistic Bathymetry |
title_full_unstemmed |
Jet Instability over Smooth, Corrugated, and Realistic Bathymetry |
title_sort |
jet instability over smooth, corrugated, and realistic bathymetry |
publishDate |
2019 |
url |
http://hdl.handle.net/10852/76718 http://urn.nb.no/URN:NBN:no-79800 https://doi.org/10.1175/JPO-D-18-0129.1 |
geographic |
Antarctic The Antarctic |
geographic_facet |
Antarctic The Antarctic |
genre |
Antarc* Antarctic |
genre_facet |
Antarc* Antarctic |
op_source |
0022-3670 |
op_relation |
http://urn.nb.no/URN:NBN:no-79800 Lacasce, Joseph Henry Escartin, Javier Chassignet, Eric P. Xu, Xiaobiao . Jet Instability over Smooth, Corrugated, and Realistic Bathymetry. Journal of Physical Oceanography. 2019, 49(2), 585-605 http://hdl.handle.net/10852/76718 1706202 info:ofi/fmt:kev:mtx:ctx&ctx_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:journal&rft.jtitle=Journal of Physical Oceanography&rft.volume=49&rft.spage=585&rft.date=2019 Journal of Physical Oceanography 49 2 585 605 https://doi.org/10.1175/JPO-D-18-0129.1 URN:NBN:no-79800 Fulltext https://www.duo.uio.no/bitstream/handle/10852/76718/2/lacasce_jpo19.pdf |
op_doi |
https://doi.org/10.1175/JPO-D-18-0129.1 |
container_title |
Journal of Physical Oceanography |
container_volume |
49 |
container_issue |
2 |
container_start_page |
585 |
op_container_end_page |
605 |
_version_ |
1766264755489603584 |