Temporal characteristics of abyssal finescale motions above rough bathymetry
Author Posting. © American Meteorological Society, 2007. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Physical Oceanography 37 (2007): 409–427, doi:10.1175/JPO2988.1. Current-...
Published in: | Journal of Physical Oceanography |
---|---|
Main Author: | |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
American Meteorological Society
2007
|
Subjects: | |
Online Access: | https://hdl.handle.net/1912/4139 |
id |
ftwhoas:oai:darchive.mblwhoilibrary.org:1912/4139 |
---|---|
record_format |
openpolar |
spelling |
ftwhoas:oai:darchive.mblwhoilibrary.org:1912/4139 2023-05-15T18:21:17+02:00 Temporal characteristics of abyssal finescale motions above rough bathymetry Toole, John M. 2007-03 application/pdf https://hdl.handle.net/1912/4139 en_US eng American Meteorological Society https://doi.org/10.1175/JPO2988.1 Journal of Physical Oceanography 37 (2007): 409-427 https://hdl.handle.net/1912/4139 doi:10.1175/JPO2988.1 Journal of Physical Oceanography 37 (2007): 409-427 doi:10.1175/JPO2988.1 Bathymetry roughness Finescale motion Abyssal flows Turbulent mixing Shear dispersion Article 2007 ftwhoas https://doi.org/10.1175/JPO2988.1 2022-05-28T22:58:11Z Author Posting. © American Meteorological Society, 2007. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Physical Oceanography 37 (2007): 409–427, doi:10.1175/JPO2988.1. Current-meter data from a two-year mooring within a fracture zone on the western flank of the Mid-Atlantic Ridge in the South Atlantic Ocean are reported. The mooring, deployed in conjunction with the Brazil Basin Tracer Release Experiment, was placed in the general area where enhanced diapycnal mixing had previously been inferred. The current-meter data characterize the velocity, temperature, shear, and temperature gradient variability as a function of frequency. Energetic velocities and shears were observed at the mooring at a variety of frequencies. In addition to semidiurnal flows, a significant amount of shear variance derived from near-inertial motions, as has been seen in a recent numerical modeling study of tidal-frequency internal wave radiation and wave–wave interaction. At times, a fortnightly modulation of the total superinertial shear variance was indicated in the data, but this signal did not dominate the records. Wave ray tracing indicates that the deeper current meters may have been placed in a shadow zone for locally generated internal tides. At shallower levels, it is suggested that dispersion, wave–wave interaction, and wave breaking effectively obscured the sources of the finescale energy. Average diapycnal diffusivity estimates inferred from a Richardson-number-based parameterization and from observations of temperature inversions at 4648 m were of the same order of magnitude as those derived from turbulent dissipation estimates and from the rate of diapycnal tracer dispersion. The mooring data thus add additional support to the idea that energetic finescale motions above rough bathymetry support enhanced turbulent diapycnal mixing in these regions. The research presented in this manuscript was ... Article in Journal/Newspaper South Atlantic Ocean Woods Hole Scientific Community: WHOAS (Woods Hole Open Access Server) Mid-Atlantic Ridge Journal of Physical Oceanography 37 3 409 427 |
institution |
Open Polar |
collection |
Woods Hole Scientific Community: WHOAS (Woods Hole Open Access Server) |
op_collection_id |
ftwhoas |
language |
English |
topic |
Bathymetry roughness Finescale motion Abyssal flows Turbulent mixing Shear dispersion |
spellingShingle |
Bathymetry roughness Finescale motion Abyssal flows Turbulent mixing Shear dispersion Toole, John M. Temporal characteristics of abyssal finescale motions above rough bathymetry |
topic_facet |
Bathymetry roughness Finescale motion Abyssal flows Turbulent mixing Shear dispersion |
description |
Author Posting. © American Meteorological Society, 2007. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Physical Oceanography 37 (2007): 409–427, doi:10.1175/JPO2988.1. Current-meter data from a two-year mooring within a fracture zone on the western flank of the Mid-Atlantic Ridge in the South Atlantic Ocean are reported. The mooring, deployed in conjunction with the Brazil Basin Tracer Release Experiment, was placed in the general area where enhanced diapycnal mixing had previously been inferred. The current-meter data characterize the velocity, temperature, shear, and temperature gradient variability as a function of frequency. Energetic velocities and shears were observed at the mooring at a variety of frequencies. In addition to semidiurnal flows, a significant amount of shear variance derived from near-inertial motions, as has been seen in a recent numerical modeling study of tidal-frequency internal wave radiation and wave–wave interaction. At times, a fortnightly modulation of the total superinertial shear variance was indicated in the data, but this signal did not dominate the records. Wave ray tracing indicates that the deeper current meters may have been placed in a shadow zone for locally generated internal tides. At shallower levels, it is suggested that dispersion, wave–wave interaction, and wave breaking effectively obscured the sources of the finescale energy. Average diapycnal diffusivity estimates inferred from a Richardson-number-based parameterization and from observations of temperature inversions at 4648 m were of the same order of magnitude as those derived from turbulent dissipation estimates and from the rate of diapycnal tracer dispersion. The mooring data thus add additional support to the idea that energetic finescale motions above rough bathymetry support enhanced turbulent diapycnal mixing in these regions. The research presented in this manuscript was ... |
format |
Article in Journal/Newspaper |
author |
Toole, John M. |
author_facet |
Toole, John M. |
author_sort |
Toole, John M. |
title |
Temporal characteristics of abyssal finescale motions above rough bathymetry |
title_short |
Temporal characteristics of abyssal finescale motions above rough bathymetry |
title_full |
Temporal characteristics of abyssal finescale motions above rough bathymetry |
title_fullStr |
Temporal characteristics of abyssal finescale motions above rough bathymetry |
title_full_unstemmed |
Temporal characteristics of abyssal finescale motions above rough bathymetry |
title_sort |
temporal characteristics of abyssal finescale motions above rough bathymetry |
publisher |
American Meteorological Society |
publishDate |
2007 |
url |
https://hdl.handle.net/1912/4139 |
geographic |
Mid-Atlantic Ridge |
geographic_facet |
Mid-Atlantic Ridge |
genre |
South Atlantic Ocean |
genre_facet |
South Atlantic Ocean |
op_source |
Journal of Physical Oceanography 37 (2007): 409-427 doi:10.1175/JPO2988.1 |
op_relation |
https://doi.org/10.1175/JPO2988.1 Journal of Physical Oceanography 37 (2007): 409-427 https://hdl.handle.net/1912/4139 doi:10.1175/JPO2988.1 |
op_doi |
https://doi.org/10.1175/JPO2988.1 |
container_title |
Journal of Physical Oceanography |
container_volume |
37 |
container_issue |
3 |
container_start_page |
409 |
op_container_end_page |
427 |
_version_ |
1766200462841741312 |