Validation of Thorpe-scale-derived vertical diffusivities against microstructure measurements in the Kerguelen region
The Thorpe scale is an energy-containing vertical overturning scale of large eddies associated with shear-generated turbulence. This study investigates indirect estimates of vertical diffusivities from the Thorpe scale method in the polar front region east of the Kerguelen Islands based on fine-scal...
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ftdoajarticles:oai:doaj.org/article:05f18f5ded1c4cab9e564ec79bea3898 2023-05-15T17:02:04+02:00 Validation of Thorpe-scale-derived vertical diffusivities against microstructure measurements in the Kerguelen region Y.-H. Park J.-H. Lee I. Durand C.-S. Hong 2014-12-01T00:00:00Z https://doi.org/10.5194/bg-11-6927-2014 https://doaj.org/article/05f18f5ded1c4cab9e564ec79bea3898 EN eng Copernicus Publications http://www.biogeosciences.net/11/6927/2014/bg-11-6927-2014.pdf https://doaj.org/toc/1726-4170 https://doaj.org/toc/1726-4189 1726-4170 1726-4189 doi:10.5194/bg-11-6927-2014 https://doaj.org/article/05f18f5ded1c4cab9e564ec79bea3898 Biogeosciences, Vol 11, Iss 23, Pp 6927-6937 (2014) Ecology QH540-549.5 Life QH501-531 Geology QE1-996.5 article 2014 ftdoajarticles https://doi.org/10.5194/bg-11-6927-2014 2022-12-30T21:57:05Z The Thorpe scale is an energy-containing vertical overturning scale of large eddies associated with shear-generated turbulence. This study investigates indirect estimates of vertical diffusivities from the Thorpe scale method in the polar front region east of the Kerguelen Islands based on fine-scale density profiles gathered during the 2011 KEOPS2 (KErguelen Ocean and Plateau compared Study 2) cruise. These diffusivities are validated in comparison with diffusivities estimated from the turbulence dissipation rate directly measured via a TurboMAP (Turbulence ocean Microstructure Acquisition Profiler) microstructure profiler. The results are sensitive to the choice of the diffusivity parameterization and the overturn ratio R o , and the optimal results have been obtained from the parameterization by Shih et al. (2005) and the R o = 0.25 criterion, rather than the parameterization by Osborn (1980) and the R o = 0.2 criterion originally suggested by Gargett and Garner (2008). The Thorpe-scale-derived diffusivities in the KEOPS2 region show a high degree of spatial variability, ranging from a canonical value of O (10 −5 ) m 2 s −1 in the Winter Water layer and in the area immediately north of the polar front to a high value of O (10 −4 ) m 2 s −1 in the seasonal thermocline between the surface mixed layer and the Winter Water. The latter high diffusivities are found especially over the shallow plateau southeast of the Kerguelen Islands and along the polar front that is attached to the escarpment northeast of the islands. The interaction of strong frontal flow with prominent bottom topography likely causes the observed elevated mixing rates. Article in Journal/Newspaper Kerguelen Islands Directory of Open Access Journals: DOAJ Articles Kerguelen Kerguelen Islands Osborn ENVELOPE(-120.378,-120.378,56.604,56.604) Biogeosciences 11 23 6927 6937 |
institution |
Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
Ecology QH540-549.5 Life QH501-531 Geology QE1-996.5 |
spellingShingle |
Ecology QH540-549.5 Life QH501-531 Geology QE1-996.5 Y.-H. Park J.-H. Lee I. Durand C.-S. Hong Validation of Thorpe-scale-derived vertical diffusivities against microstructure measurements in the Kerguelen region |
topic_facet |
Ecology QH540-549.5 Life QH501-531 Geology QE1-996.5 |
description |
The Thorpe scale is an energy-containing vertical overturning scale of large eddies associated with shear-generated turbulence. This study investigates indirect estimates of vertical diffusivities from the Thorpe scale method in the polar front region east of the Kerguelen Islands based on fine-scale density profiles gathered during the 2011 KEOPS2 (KErguelen Ocean and Plateau compared Study 2) cruise. These diffusivities are validated in comparison with diffusivities estimated from the turbulence dissipation rate directly measured via a TurboMAP (Turbulence ocean Microstructure Acquisition Profiler) microstructure profiler. The results are sensitive to the choice of the diffusivity parameterization and the overturn ratio R o , and the optimal results have been obtained from the parameterization by Shih et al. (2005) and the R o = 0.25 criterion, rather than the parameterization by Osborn (1980) and the R o = 0.2 criterion originally suggested by Gargett and Garner (2008). The Thorpe-scale-derived diffusivities in the KEOPS2 region show a high degree of spatial variability, ranging from a canonical value of O (10 −5 ) m 2 s −1 in the Winter Water layer and in the area immediately north of the polar front to a high value of O (10 −4 ) m 2 s −1 in the seasonal thermocline between the surface mixed layer and the Winter Water. The latter high diffusivities are found especially over the shallow plateau southeast of the Kerguelen Islands and along the polar front that is attached to the escarpment northeast of the islands. The interaction of strong frontal flow with prominent bottom topography likely causes the observed elevated mixing rates. |
format |
Article in Journal/Newspaper |
author |
Y.-H. Park J.-H. Lee I. Durand C.-S. Hong |
author_facet |
Y.-H. Park J.-H. Lee I. Durand C.-S. Hong |
author_sort |
Y.-H. Park |
title |
Validation of Thorpe-scale-derived vertical diffusivities against microstructure measurements in the Kerguelen region |
title_short |
Validation of Thorpe-scale-derived vertical diffusivities against microstructure measurements in the Kerguelen region |
title_full |
Validation of Thorpe-scale-derived vertical diffusivities against microstructure measurements in the Kerguelen region |
title_fullStr |
Validation of Thorpe-scale-derived vertical diffusivities against microstructure measurements in the Kerguelen region |
title_full_unstemmed |
Validation of Thorpe-scale-derived vertical diffusivities against microstructure measurements in the Kerguelen region |
title_sort |
validation of thorpe-scale-derived vertical diffusivities against microstructure measurements in the kerguelen region |
publisher |
Copernicus Publications |
publishDate |
2014 |
url |
https://doi.org/10.5194/bg-11-6927-2014 https://doaj.org/article/05f18f5ded1c4cab9e564ec79bea3898 |
long_lat |
ENVELOPE(-120.378,-120.378,56.604,56.604) |
geographic |
Kerguelen Kerguelen Islands Osborn |
geographic_facet |
Kerguelen Kerguelen Islands Osborn |
genre |
Kerguelen Islands |
genre_facet |
Kerguelen Islands |
op_source |
Biogeosciences, Vol 11, Iss 23, Pp 6927-6937 (2014) |
op_relation |
http://www.biogeosciences.net/11/6927/2014/bg-11-6927-2014.pdf https://doaj.org/toc/1726-4170 https://doaj.org/toc/1726-4189 1726-4170 1726-4189 doi:10.5194/bg-11-6927-2014 https://doaj.org/article/05f18f5ded1c4cab9e564ec79bea3898 |
op_doi |
https://doi.org/10.5194/bg-11-6927-2014 |
container_title |
Biogeosciences |
container_volume |
11 |
container_issue |
23 |
container_start_page |
6927 |
op_container_end_page |
6937 |
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1766055298790850560 |