The dissipation of kinetic energy in the Lofoten Basin Eddy
Ocean microstructure, current, and hydrography observations from June 2016 are used to characterize the turbulence structure of the Lofoten Basin eddy (LBE), a long-lived anticyclone in the Norwegian Sea. The LBE had an azimuthal peak velocity of 0.8 m s−1 at 950-m depth and 22-km radial distance fr...
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ftunivbergen:oai:bora.uib.no:1956/19342 2023-05-15T17:08:16+02:00 The dissipation of kinetic energy in the Lofoten Basin Eddy Fer, Ilker Bosse, Anthony Ferron, Bruno Bouruet-Aubertot, Pascale 2018-09-06T16:06:35Z application/pdf https://hdl.handle.net/1956/19342 https://doi.org/10.1175/jpo-d-17-0244.1 eng eng American Meteorological Society Norges forskningsråd: 250784 urn:issn:0022-3670 urn:issn:1520-0485 https://hdl.handle.net/1956/19342 https://doi.org/10.1175/jpo-d-17-0244.1 cristin:1581711 Attribution CC BY http://creativecommons.org/licenses/by/4.0 Copyright 2018 American Meteorological Society Journal of Physical Oceanography North Atlantic Ocean Eddies Internal waves Mixing Turbulence VDP::Matematikk og naturvitenskap: 400::Geofag: 450::Oseanografi: 452 VDP::Mathematics and natural scienses: 400::Geosciences: 450::Oceanography: 452 Peer reviewed Journal article 2018 ftunivbergen https://doi.org/10.1175/jpo-d-17-0244.1 2023-03-14T17:43:47Z Ocean microstructure, current, and hydrography observations from June 2016 are used to characterize the turbulence structure of the Lofoten Basin eddy (LBE), a long-lived anticyclone in the Norwegian Sea. The LBE had an azimuthal peak velocity of 0.8 m s−1 at 950-m depth and 22-km radial distance from its center and a core relative vorticity reaching −0.7f (f is the local Coriolis parameter). When contrasted to a reference station in a relatively quiescent part of the basin, the LBE was significantly turbulent between 750 and 2000 m, exceeding the dissipation rates ε in the reference station by up to two orders of magnitude. Dissipation rates were elevated particularly in the core and at the rim below the swirl velocity maximum, reaching 10−8 W kg−1. The sources of energy for the observed turbulence are the background shear (gradient Richardson number less than unity) and the subinertial energy trapped by the negative vorticity of the eddy. Idealized ray-tracing calculations show that the vertical and lateral changes in stratification, shear, and vorticity allow subinertial waves to be trapped within the LBE. Spectral analysis shows increased high-wavenumber clockwise-polarized shear variance in the core and rim regions, consistent with downward-propagating near-inertial waves (vertical wavelengths of order 100 m and energy levels 3 to 10 times the canonical open-ocean level). The energetic packets with a distinct downward energy propagation are typically accompanied with an increase in dissipation levels. Based on these summer observations, the time scale to drain the volume-integrated total energy of the LBE is 14 years. publishedVersion Article in Journal/Newspaper Lofoten North Atlantic Norwegian Sea University of Bergen: Bergen Open Research Archive (BORA-UiB) Lofoten Lofoten Basin ENVELOPE(4.000,4.000,70.000,70.000) Norwegian Sea Journal of Physical Oceanography 48 6 1299 1316 |
institution |
Open Polar |
collection |
University of Bergen: Bergen Open Research Archive (BORA-UiB) |
op_collection_id |
ftunivbergen |
language |
English |
topic |
North Atlantic Ocean Eddies Internal waves Mixing Turbulence VDP::Matematikk og naturvitenskap: 400::Geofag: 450::Oseanografi: 452 VDP::Mathematics and natural scienses: 400::Geosciences: 450::Oceanography: 452 |
spellingShingle |
North Atlantic Ocean Eddies Internal waves Mixing Turbulence VDP::Matematikk og naturvitenskap: 400::Geofag: 450::Oseanografi: 452 VDP::Mathematics and natural scienses: 400::Geosciences: 450::Oceanography: 452 Fer, Ilker Bosse, Anthony Ferron, Bruno Bouruet-Aubertot, Pascale The dissipation of kinetic energy in the Lofoten Basin Eddy |
topic_facet |
North Atlantic Ocean Eddies Internal waves Mixing Turbulence VDP::Matematikk og naturvitenskap: 400::Geofag: 450::Oseanografi: 452 VDP::Mathematics and natural scienses: 400::Geosciences: 450::Oceanography: 452 |
description |
Ocean microstructure, current, and hydrography observations from June 2016 are used to characterize the turbulence structure of the Lofoten Basin eddy (LBE), a long-lived anticyclone in the Norwegian Sea. The LBE had an azimuthal peak velocity of 0.8 m s−1 at 950-m depth and 22-km radial distance from its center and a core relative vorticity reaching −0.7f (f is the local Coriolis parameter). When contrasted to a reference station in a relatively quiescent part of the basin, the LBE was significantly turbulent between 750 and 2000 m, exceeding the dissipation rates ε in the reference station by up to two orders of magnitude. Dissipation rates were elevated particularly in the core and at the rim below the swirl velocity maximum, reaching 10−8 W kg−1. The sources of energy for the observed turbulence are the background shear (gradient Richardson number less than unity) and the subinertial energy trapped by the negative vorticity of the eddy. Idealized ray-tracing calculations show that the vertical and lateral changes in stratification, shear, and vorticity allow subinertial waves to be trapped within the LBE. Spectral analysis shows increased high-wavenumber clockwise-polarized shear variance in the core and rim regions, consistent with downward-propagating near-inertial waves (vertical wavelengths of order 100 m and energy levels 3 to 10 times the canonical open-ocean level). The energetic packets with a distinct downward energy propagation are typically accompanied with an increase in dissipation levels. Based on these summer observations, the time scale to drain the volume-integrated total energy of the LBE is 14 years. publishedVersion |
format |
Article in Journal/Newspaper |
author |
Fer, Ilker Bosse, Anthony Ferron, Bruno Bouruet-Aubertot, Pascale |
author_facet |
Fer, Ilker Bosse, Anthony Ferron, Bruno Bouruet-Aubertot, Pascale |
author_sort |
Fer, Ilker |
title |
The dissipation of kinetic energy in the Lofoten Basin Eddy |
title_short |
The dissipation of kinetic energy in the Lofoten Basin Eddy |
title_full |
The dissipation of kinetic energy in the Lofoten Basin Eddy |
title_fullStr |
The dissipation of kinetic energy in the Lofoten Basin Eddy |
title_full_unstemmed |
The dissipation of kinetic energy in the Lofoten Basin Eddy |
title_sort |
dissipation of kinetic energy in the lofoten basin eddy |
publisher |
American Meteorological Society |
publishDate |
2018 |
url |
https://hdl.handle.net/1956/19342 https://doi.org/10.1175/jpo-d-17-0244.1 |
long_lat |
ENVELOPE(4.000,4.000,70.000,70.000) |
geographic |
Lofoten Lofoten Basin Norwegian Sea |
geographic_facet |
Lofoten Lofoten Basin Norwegian Sea |
genre |
Lofoten North Atlantic Norwegian Sea |
genre_facet |
Lofoten North Atlantic Norwegian Sea |
op_source |
Journal of Physical Oceanography |
op_relation |
Norges forskningsråd: 250784 urn:issn:0022-3670 urn:issn:1520-0485 https://hdl.handle.net/1956/19342 https://doi.org/10.1175/jpo-d-17-0244.1 cristin:1581711 |
op_rights |
Attribution CC BY http://creativecommons.org/licenses/by/4.0 Copyright 2018 American Meteorological Society |
op_doi |
https://doi.org/10.1175/jpo-d-17-0244.1 |
container_title |
Journal of Physical Oceanography |
container_volume |
48 |
container_issue |
6 |
container_start_page |
1299 |
op_container_end_page |
1316 |
_version_ |
1766063986059509760 |