Behavior and mixing of a cold intermediate layer near a sloping boundary
As in many other subarctic basins, a cold intermediate layer (CIL) is found during ice-free months in the Lower St. Lawrence Estuary (LSLE), Canada. This study examines the behavior of the CIL above the sloping bottom using a high-resolution mooring deployed on the northern side of the estuary. Obse...
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Language: | English |
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ftnioz:oai:imis.nioz.nl:245844 2023-05-15T18:28:30+02:00 Behavior and mixing of a cold intermediate layer near a sloping boundary Cyr, F. Bourgault, D. Galbraith, P.S. 2015 application/pdf https://www.vliz.be/imisdocs/publications/89/281889.pdf en eng info:eu-repo/semantics/altIdentifier/wos/000350481400004 info:eu-repo/semantics/altIdentifier/doi/doi.org/10.1007/s10236-014-0799-1 https://www.vliz.be/imisdocs/publications/89/281889.pdf info:eu-repo/semantics/openAccess %3Ci%3EOcean+Dynamics+65%3C%2Fi%3E%3A+357-374.+%3Ca+href%3D%22https%3A%2F%2Fdx.doi.org%2F10.1007%2Fs10236-014-0799-1%22+target%3D%22_blank%22%3Ehttps%3A%2F%2Fdx.doi.org%2F10.1007%2Fs10236-014-0799-1%3C%2Fa%3E info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion 2015 ftnioz https://doi.org/10.1007/s10236-014-0799-1 2022-05-01T14:01:17Z As in many other subarctic basins, a cold intermediate layer (CIL) is found during ice-free months in the Lower St. Lawrence Estuary (LSLE), Canada. This study examines the behavior of the CIL above the sloping bottom using a high-resolution mooring deployed on the northern side of the estuary. Observations show successive swashes/backwashes of the CIL on the slope at a semi-diurnal frequency. It is shown that these upslope and downslope motions are likely caused by internal tides generated at the nearby channel head sill. Quantification of mixing from 322 turbulence casts reveals that in the bottom 10 m of the water column, the time-average dissipation rate of turbulent kinetic energy is ? 10 m = 1.6×10-7Wkg-1, an order of magnitude greater than found in the interior of the basin, far from boundaries. Near-bottom dissipation during the flood phase of the M2 tide cycle (upslope flow) is about four times greater than during the ebb phase (downslope flow). Bottom shear stress, shear instabilities, and internal wave scattering are considered as potential boundary mixing mechanisms near the seabed. In the interior of the water column, far from the bottom, increasing dissipation rates are observed with both increasing stratification and shear, which suggests some control of the dissipation by the internal wave field. However, poor fits with a parametrization for large-scale wave-wave interactions suggests that the mixing is partly driven by more complex non-linear and/or smaller scale waves. Article in Journal/Newspaper Subarctic NIOZ Repository (Royal Netherlands Institute for Sea Research) Canada Ocean Dynamics 65 3 357 374 |
institution |
Open Polar |
collection |
NIOZ Repository (Royal Netherlands Institute for Sea Research) |
op_collection_id |
ftnioz |
language |
English |
description |
As in many other subarctic basins, a cold intermediate layer (CIL) is found during ice-free months in the Lower St. Lawrence Estuary (LSLE), Canada. This study examines the behavior of the CIL above the sloping bottom using a high-resolution mooring deployed on the northern side of the estuary. Observations show successive swashes/backwashes of the CIL on the slope at a semi-diurnal frequency. It is shown that these upslope and downslope motions are likely caused by internal tides generated at the nearby channel head sill. Quantification of mixing from 322 turbulence casts reveals that in the bottom 10 m of the water column, the time-average dissipation rate of turbulent kinetic energy is ? 10 m = 1.6×10-7Wkg-1, an order of magnitude greater than found in the interior of the basin, far from boundaries. Near-bottom dissipation during the flood phase of the M2 tide cycle (upslope flow) is about four times greater than during the ebb phase (downslope flow). Bottom shear stress, shear instabilities, and internal wave scattering are considered as potential boundary mixing mechanisms near the seabed. In the interior of the water column, far from the bottom, increasing dissipation rates are observed with both increasing stratification and shear, which suggests some control of the dissipation by the internal wave field. However, poor fits with a parametrization for large-scale wave-wave interactions suggests that the mixing is partly driven by more complex non-linear and/or smaller scale waves. |
format |
Article in Journal/Newspaper |
author |
Cyr, F. Bourgault, D. Galbraith, P.S. |
spellingShingle |
Cyr, F. Bourgault, D. Galbraith, P.S. Behavior and mixing of a cold intermediate layer near a sloping boundary |
author_facet |
Cyr, F. Bourgault, D. Galbraith, P.S. |
author_sort |
Cyr, F. |
title |
Behavior and mixing of a cold intermediate layer near a sloping boundary |
title_short |
Behavior and mixing of a cold intermediate layer near a sloping boundary |
title_full |
Behavior and mixing of a cold intermediate layer near a sloping boundary |
title_fullStr |
Behavior and mixing of a cold intermediate layer near a sloping boundary |
title_full_unstemmed |
Behavior and mixing of a cold intermediate layer near a sloping boundary |
title_sort |
behavior and mixing of a cold intermediate layer near a sloping boundary |
publishDate |
2015 |
url |
https://www.vliz.be/imisdocs/publications/89/281889.pdf |
geographic |
Canada |
geographic_facet |
Canada |
genre |
Subarctic |
genre_facet |
Subarctic |
op_source |
%3Ci%3EOcean+Dynamics+65%3C%2Fi%3E%3A+357-374.+%3Ca+href%3D%22https%3A%2F%2Fdx.doi.org%2F10.1007%2Fs10236-014-0799-1%22+target%3D%22_blank%22%3Ehttps%3A%2F%2Fdx.doi.org%2F10.1007%2Fs10236-014-0799-1%3C%2Fa%3E |
op_relation |
info:eu-repo/semantics/altIdentifier/wos/000350481400004 info:eu-repo/semantics/altIdentifier/doi/doi.org/10.1007/s10236-014-0799-1 https://www.vliz.be/imisdocs/publications/89/281889.pdf |
op_rights |
info:eu-repo/semantics/openAccess |
op_doi |
https://doi.org/10.1007/s10236-014-0799-1 |
container_title |
Ocean Dynamics |
container_volume |
65 |
container_issue |
3 |
container_start_page |
357 |
op_container_end_page |
374 |
_version_ |
1766211007622938624 |