Mesoscale eddy dissipation by a "zoo" of submesoscale processes at a western boundary
© The Author(s), 2020. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Evans, D. G., Frajka-Williams, E., Garabato, A. C. N., Polzin, K. L., & Forryan, A. Mesoscale eddy dissipation by a "zoo" of submesosc...
Published in: | Journal of Geophysical Research: Oceans |
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American Geophysical Union
2020
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Online Access: | https://hdl.handle.net/1912/26704 |
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ftwhoas:oai:darchive.mblwhoilibrary.org:1912/26704 2023-05-15T17:36:05+02:00 Mesoscale eddy dissipation by a "zoo" of submesoscale processes at a western boundary Evans, Dafydd Gwyn Frajka-Williams, Eleanor E. Naveira Garabato, Alberto C. Polzin, Kurt L. Forryan, Alexander 2020-11-04 https://hdl.handle.net/1912/26704 unknown American Geophysical Union https://doi.org/10.1029/2020JC016246 Evans, D. G., Frajka-Williams, E., Garabato, A. C. N., Polzin, K. L., & Forryan, A. (2020). Mesoscale eddy dissipation by a "zoo" of submesoscale processes at a western boundary. Journal of Geophysical Research: Oceans, 125(11), e2020JC016246. https://hdl.handle.net/1912/26704 doi:10.1029/2020JC016246 Attribution 4.0 International http://creativecommons.org/licenses/by/4.0/ CC-BY Evans, D. G., Frajka-Williams, E., Garabato, A. C. N., Polzin, K. L., & Forryan, A. (2020). Mesoscale eddy dissipation by a "zoo" of submesoscale processes at a western boundary. Journal of Geophysical Research: Oceans, 125(11), e2020JC016246. doi:10.1029/2020JC016246 Direct energy cascade Eddy-topography interactions Energy Instability Mesoscale eddies Turbulence Article 2020 ftwhoas https://doi.org/10.1029/2020JC016246 2022-10-29T22:57:22Z © The Author(s), 2020. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Evans, D. G., Frajka-Williams, E., Garabato, A. C. N., Polzin, K. L., & Forryan, A. Mesoscale eddy dissipation by a "zoo" of submesoscale processes at a western boundary. Journal of Geophysical Research: Oceans, 125(11), (2020): e2020JC016246, doi:10.1029/2020JC016246. Mesoscale eddies are ubiquitous dynamical features that tend to propagate westward and disappear along ocean western boundaries. Using a multiscale observational study, we assess the extent to which eddies dissipate via a direct cascade of energy at a western boundary. We analyze data from a ship‐based microstructure and velocity survey, and an 18‐month mooring deployment, to document the dissipation of energy in anticyclonic and cyclonic eddies impinging on the topographic slope east of the Bahamas, in the North Atlantic Ocean. These observations reveal high levels of turbulence where the steep and rough topographic slope modified the intensified northward flow associated with, in particular, anticyclonic eddies. Elevated dissipation was observed both near‐bottom and at mid depths (200–800 m). Near‐bottom turbulence occurred in the lee of a protruding escarpment, where elevated Froude numbers suggest hydraulic control. Energy was also radiated in the form of upward‐propagating internal waves. Elevated dissipation at mid depths occurred in regions of strong vertical shear, where the topographic slope modified the vertical structure of the northward eddy flow. Here, low Richardson numbers and a local change in the isopycnal gradient of potential vorticity (PV) suggest that the elevated dissipation was associated with horizontal shear instability. Elevated mid‐depth dissipation was also induced by topographic steering of the flow. This led to large anticyclonic vorticity and negative PV adjacent to the topographic slope, suggesting that centrifugal instability underpinned the local enhancement ... Article in Journal/Newspaper North Atlantic Woods Hole Scientific Community: WHOAS (Woods Hole Open Access Server) Journal of Geophysical Research: Oceans 125 11 |
institution |
Open Polar |
collection |
Woods Hole Scientific Community: WHOAS (Woods Hole Open Access Server) |
op_collection_id |
ftwhoas |
language |
unknown |
topic |
Direct energy cascade Eddy-topography interactions Energy Instability Mesoscale eddies Turbulence |
spellingShingle |
Direct energy cascade Eddy-topography interactions Energy Instability Mesoscale eddies Turbulence Evans, Dafydd Gwyn Frajka-Williams, Eleanor E. Naveira Garabato, Alberto C. Polzin, Kurt L. Forryan, Alexander Mesoscale eddy dissipation by a "zoo" of submesoscale processes at a western boundary |
topic_facet |
Direct energy cascade Eddy-topography interactions Energy Instability Mesoscale eddies Turbulence |
description |
© The Author(s), 2020. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Evans, D. G., Frajka-Williams, E., Garabato, A. C. N., Polzin, K. L., & Forryan, A. Mesoscale eddy dissipation by a "zoo" of submesoscale processes at a western boundary. Journal of Geophysical Research: Oceans, 125(11), (2020): e2020JC016246, doi:10.1029/2020JC016246. Mesoscale eddies are ubiquitous dynamical features that tend to propagate westward and disappear along ocean western boundaries. Using a multiscale observational study, we assess the extent to which eddies dissipate via a direct cascade of energy at a western boundary. We analyze data from a ship‐based microstructure and velocity survey, and an 18‐month mooring deployment, to document the dissipation of energy in anticyclonic and cyclonic eddies impinging on the topographic slope east of the Bahamas, in the North Atlantic Ocean. These observations reveal high levels of turbulence where the steep and rough topographic slope modified the intensified northward flow associated with, in particular, anticyclonic eddies. Elevated dissipation was observed both near‐bottom and at mid depths (200–800 m). Near‐bottom turbulence occurred in the lee of a protruding escarpment, where elevated Froude numbers suggest hydraulic control. Energy was also radiated in the form of upward‐propagating internal waves. Elevated dissipation at mid depths occurred in regions of strong vertical shear, where the topographic slope modified the vertical structure of the northward eddy flow. Here, low Richardson numbers and a local change in the isopycnal gradient of potential vorticity (PV) suggest that the elevated dissipation was associated with horizontal shear instability. Elevated mid‐depth dissipation was also induced by topographic steering of the flow. This led to large anticyclonic vorticity and negative PV adjacent to the topographic slope, suggesting that centrifugal instability underpinned the local enhancement ... |
format |
Article in Journal/Newspaper |
author |
Evans, Dafydd Gwyn Frajka-Williams, Eleanor E. Naveira Garabato, Alberto C. Polzin, Kurt L. Forryan, Alexander |
author_facet |
Evans, Dafydd Gwyn Frajka-Williams, Eleanor E. Naveira Garabato, Alberto C. Polzin, Kurt L. Forryan, Alexander |
author_sort |
Evans, Dafydd Gwyn |
title |
Mesoscale eddy dissipation by a "zoo" of submesoscale processes at a western boundary |
title_short |
Mesoscale eddy dissipation by a "zoo" of submesoscale processes at a western boundary |
title_full |
Mesoscale eddy dissipation by a "zoo" of submesoscale processes at a western boundary |
title_fullStr |
Mesoscale eddy dissipation by a "zoo" of submesoscale processes at a western boundary |
title_full_unstemmed |
Mesoscale eddy dissipation by a "zoo" of submesoscale processes at a western boundary |
title_sort |
mesoscale eddy dissipation by a "zoo" of submesoscale processes at a western boundary |
publisher |
American Geophysical Union |
publishDate |
2020 |
url |
https://hdl.handle.net/1912/26704 |
genre |
North Atlantic |
genre_facet |
North Atlantic |
op_source |
Evans, D. G., Frajka-Williams, E., Garabato, A. C. N., Polzin, K. L., & Forryan, A. (2020). Mesoscale eddy dissipation by a "zoo" of submesoscale processes at a western boundary. Journal of Geophysical Research: Oceans, 125(11), e2020JC016246. doi:10.1029/2020JC016246 |
op_relation |
https://doi.org/10.1029/2020JC016246 Evans, D. G., Frajka-Williams, E., Garabato, A. C. N., Polzin, K. L., & Forryan, A. (2020). Mesoscale eddy dissipation by a "zoo" of submesoscale processes at a western boundary. Journal of Geophysical Research: Oceans, 125(11), e2020JC016246. https://hdl.handle.net/1912/26704 doi:10.1029/2020JC016246 |
op_rights |
Attribution 4.0 International http://creativecommons.org/licenses/by/4.0/ |
op_rightsnorm |
CC-BY |
op_doi |
https://doi.org/10.1029/2020JC016246 |
container_title |
Journal of Geophysical Research: Oceans |
container_volume |
125 |
container_issue |
11 |
_version_ |
1766135453916856320 |