Mixing in the stratified interface of the Faroe Bank Channel overflow: the role of transverse circulation and internal waves
The overflow of cold water across the Faroe Bank Channel sill is a significant volume flux of dense water to the North Atlantic Ocean. Using observations of hydrography, current and microstructure from a 1 week cruise and 2 month long time series from moored instruments, we address the role of trans...
Published in: | Journal of Geophysical Research: Oceans |
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Language: | English |
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Online Access: | http://hdl.handle.net/11250/2460483 https://doi.org/10.1029/2010JC006805 |
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ftntnutrondheimi:oai:ntnuopen.ntnu.no:11250/2460483 2023-05-15T17:35:24+02:00 Mixing in the stratified interface of the Faroe Bank Channel overflow: the role of transverse circulation and internal waves Seim, Knut Sponheim Fer, Ilker 2011 http://hdl.handle.net/11250/2460483 https://doi.org/10.1029/2010JC006805 eng eng American Geophysical Union (AGU) Norges forskningsråd: 204867 Journal of Geophysical Research. 2011, 116 . urn:issn:0148-0227 http://hdl.handle.net/11250/2460483 https://doi.org/10.1029/2010JC006805 cristin:804890 14 116 Journal of Geophysical Research VDP::Oseanografi: 452 VDP::Oceanography: 452 Journal article Peer reviewed 2011 ftntnutrondheimi https://doi.org/10.1029/2010JC006805 2019-09-17T06:52:31Z The overflow of cold water across the Faroe Bank Channel sill is a significant volume flux of dense water to the North Atlantic Ocean. Using observations of hydrography, current and microstructure from a 1 week cruise and 2 month long time series from moored instruments, we address the role of transverse circulation and internal waves in mixing in the stratified 100 m thick plume‐ambient interface. The streamwise momentum budget is dominated by a balance between the pressure gradient and bottom friction; the entrainment stress is negligible. The transverse momentum budget is in geostrophic balance, and the transverse velocity variability is governed by the internal streamwise pressure gradient. The transverse geostrophic flow in the interfacial layer is opposed by the bottom Ekman transport. The shear associated with the interfacial jet lowers the Richardson number and enhances dissipation rates. Convective overturning events observed on the upslope side suggest a link between the transverse circulation and the vertical mixing on the upper slope. Several independent threads of evidence support the transverse circulation as an important mixing mechanism for the overflow plume. In the ambient, dissipation rates inferred from fine‐scale shear and density profile measurements are in good agreement with direct measurements, supporting internal wave breaking as a dominant mechanism for dissipation of turbulent energy. In the interfacial layer, spectral distribution of internal wavefield is energetic. In addition to shear‐induced mixing and entrainment in the interfacial layer, internal wave breaking is likely to be important for the dissipation of turbulent energy and should not be ignored. publishedVersion Copyright 2011 by the American Geophysical Union. Article in Journal/Newspaper North Atlantic NTNU Open Archive (Norwegian University of Science and Technology) Faroe Bank ENVELOPE(-8.667,-8.667,60.917,60.917) Journal of Geophysical Research: Oceans 116 C7 |
institution |
Open Polar |
collection |
NTNU Open Archive (Norwegian University of Science and Technology) |
op_collection_id |
ftntnutrondheimi |
language |
English |
topic |
VDP::Oseanografi: 452 VDP::Oceanography: 452 |
spellingShingle |
VDP::Oseanografi: 452 VDP::Oceanography: 452 Seim, Knut Sponheim Fer, Ilker Mixing in the stratified interface of the Faroe Bank Channel overflow: the role of transverse circulation and internal waves |
topic_facet |
VDP::Oseanografi: 452 VDP::Oceanography: 452 |
description |
The overflow of cold water across the Faroe Bank Channel sill is a significant volume flux of dense water to the North Atlantic Ocean. Using observations of hydrography, current and microstructure from a 1 week cruise and 2 month long time series from moored instruments, we address the role of transverse circulation and internal waves in mixing in the stratified 100 m thick plume‐ambient interface. The streamwise momentum budget is dominated by a balance between the pressure gradient and bottom friction; the entrainment stress is negligible. The transverse momentum budget is in geostrophic balance, and the transverse velocity variability is governed by the internal streamwise pressure gradient. The transverse geostrophic flow in the interfacial layer is opposed by the bottom Ekman transport. The shear associated with the interfacial jet lowers the Richardson number and enhances dissipation rates. Convective overturning events observed on the upslope side suggest a link between the transverse circulation and the vertical mixing on the upper slope. Several independent threads of evidence support the transverse circulation as an important mixing mechanism for the overflow plume. In the ambient, dissipation rates inferred from fine‐scale shear and density profile measurements are in good agreement with direct measurements, supporting internal wave breaking as a dominant mechanism for dissipation of turbulent energy. In the interfacial layer, spectral distribution of internal wavefield is energetic. In addition to shear‐induced mixing and entrainment in the interfacial layer, internal wave breaking is likely to be important for the dissipation of turbulent energy and should not be ignored. publishedVersion Copyright 2011 by the American Geophysical Union. |
format |
Article in Journal/Newspaper |
author |
Seim, Knut Sponheim Fer, Ilker |
author_facet |
Seim, Knut Sponheim Fer, Ilker |
author_sort |
Seim, Knut Sponheim |
title |
Mixing in the stratified interface of the Faroe Bank Channel overflow: the role of transverse circulation and internal waves |
title_short |
Mixing in the stratified interface of the Faroe Bank Channel overflow: the role of transverse circulation and internal waves |
title_full |
Mixing in the stratified interface of the Faroe Bank Channel overflow: the role of transverse circulation and internal waves |
title_fullStr |
Mixing in the stratified interface of the Faroe Bank Channel overflow: the role of transverse circulation and internal waves |
title_full_unstemmed |
Mixing in the stratified interface of the Faroe Bank Channel overflow: the role of transverse circulation and internal waves |
title_sort |
mixing in the stratified interface of the faroe bank channel overflow: the role of transverse circulation and internal waves |
publisher |
American Geophysical Union (AGU) |
publishDate |
2011 |
url |
http://hdl.handle.net/11250/2460483 https://doi.org/10.1029/2010JC006805 |
long_lat |
ENVELOPE(-8.667,-8.667,60.917,60.917) |
geographic |
Faroe Bank |
geographic_facet |
Faroe Bank |
genre |
North Atlantic |
genre_facet |
North Atlantic |
op_source |
14 116 Journal of Geophysical Research |
op_relation |
Norges forskningsråd: 204867 Journal of Geophysical Research. 2011, 116 . urn:issn:0148-0227 http://hdl.handle.net/11250/2460483 https://doi.org/10.1029/2010JC006805 cristin:804890 |
op_doi |
https://doi.org/10.1029/2010JC006805 |
container_title |
Journal of Geophysical Research: Oceans |
container_volume |
116 |
container_issue |
C7 |
_version_ |
1766134548343554048 |