Seismic imaging of a thermohaline staircase in the western tropical North Atlantic
Multichannel seismic data acquired in the Lesser Antilles in the western tropical North Atlantic indicate that the seismic reflection method has imaged an oceanic thermohaline staircase. Synthetic acoustic modeling using measured density and sound speed profiles corroborates inferences from the seis...
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ftdoajarticles:oai:doaj.org/article:ee4ac5681d274baa81cc895641f91ea8 2023-05-15T17:31:03+02:00 Seismic imaging of a thermohaline staircase in the western tropical North Atlantic I. Fer P. Nandi W. S. Holbrook R. W. Schmitt P. Páramo 2010-07-01T00:00:00Z https://doi.org/10.5194/os-6-621-2010 https://doaj.org/article/ee4ac5681d274baa81cc895641f91ea8 EN eng Copernicus Publications http://www.ocean-sci.net/6/621/2010/os-6-621-2010.pdf https://doaj.org/toc/1812-0784 https://doaj.org/toc/1812-0792 doi:10.5194/os-6-621-2010 1812-0784 1812-0792 https://doaj.org/article/ee4ac5681d274baa81cc895641f91ea8 Ocean Science, Vol 6, Iss 3, Pp 621-631 (2010) Geography. Anthropology. Recreation G Environmental sciences GE1-350 article 2010 ftdoajarticles https://doi.org/10.5194/os-6-621-2010 2022-12-31T03:25:21Z Multichannel seismic data acquired in the Lesser Antilles in the western tropical North Atlantic indicate that the seismic reflection method has imaged an oceanic thermohaline staircase. Synthetic acoustic modeling using measured density and sound speed profiles corroborates inferences from the seismic data. In a small portion of the seismic image, laterally coherent, uniform layers are present at depths ranging from 550–700 m and have a separation of ~20 m, with thicknesses increasing with depth. The reflection coefficient, a measure of the acoustic impedance contrasts across these reflective interfaces, is one order of magnitude greater than background noise. Hydrography sampled in previous surveys suggests that the layers are a permanent feature of the region. Spectral analysis of layer horizons in the thermohaline staircase indicates that internal wave activity is anomalously low, suggesting weak internal wave-induced turbulence. Results from two independent measurements, the application of a finescale parameterization to observed high-resolution velocity profiles and direct measurements of turbulent dissipation rate, confirm these low levels of turbulence. The lack of internal wave-induced turbulence may allow for the maintenance of the staircase or may be due to suppression by the double-diffusive convection within the staircase. Our observations show the potential for seismic oceanography to contribute to an improved understanding of occurrence rates and the geographical distribution of thermohaline staircases, and should thereby improve estimates of vertical mixing rates ascribable to salt fingering in the global ocean. Article in Journal/Newspaper North Atlantic Directory of Open Access Journals: DOAJ Articles Ocean Science 6 3 621 631 |
institution |
Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
Geography. Anthropology. Recreation G Environmental sciences GE1-350 |
spellingShingle |
Geography. Anthropology. Recreation G Environmental sciences GE1-350 I. Fer P. Nandi W. S. Holbrook R. W. Schmitt P. Páramo Seismic imaging of a thermohaline staircase in the western tropical North Atlantic |
topic_facet |
Geography. Anthropology. Recreation G Environmental sciences GE1-350 |
description |
Multichannel seismic data acquired in the Lesser Antilles in the western tropical North Atlantic indicate that the seismic reflection method has imaged an oceanic thermohaline staircase. Synthetic acoustic modeling using measured density and sound speed profiles corroborates inferences from the seismic data. In a small portion of the seismic image, laterally coherent, uniform layers are present at depths ranging from 550–700 m and have a separation of ~20 m, with thicknesses increasing with depth. The reflection coefficient, a measure of the acoustic impedance contrasts across these reflective interfaces, is one order of magnitude greater than background noise. Hydrography sampled in previous surveys suggests that the layers are a permanent feature of the region. Spectral analysis of layer horizons in the thermohaline staircase indicates that internal wave activity is anomalously low, suggesting weak internal wave-induced turbulence. Results from two independent measurements, the application of a finescale parameterization to observed high-resolution velocity profiles and direct measurements of turbulent dissipation rate, confirm these low levels of turbulence. The lack of internal wave-induced turbulence may allow for the maintenance of the staircase or may be due to suppression by the double-diffusive convection within the staircase. Our observations show the potential for seismic oceanography to contribute to an improved understanding of occurrence rates and the geographical distribution of thermohaline staircases, and should thereby improve estimates of vertical mixing rates ascribable to salt fingering in the global ocean. |
format |
Article in Journal/Newspaper |
author |
I. Fer P. Nandi W. S. Holbrook R. W. Schmitt P. Páramo |
author_facet |
I. Fer P. Nandi W. S. Holbrook R. W. Schmitt P. Páramo |
author_sort |
I. Fer |
title |
Seismic imaging of a thermohaline staircase in the western tropical North Atlantic |
title_short |
Seismic imaging of a thermohaline staircase in the western tropical North Atlantic |
title_full |
Seismic imaging of a thermohaline staircase in the western tropical North Atlantic |
title_fullStr |
Seismic imaging of a thermohaline staircase in the western tropical North Atlantic |
title_full_unstemmed |
Seismic imaging of a thermohaline staircase in the western tropical North Atlantic |
title_sort |
seismic imaging of a thermohaline staircase in the western tropical north atlantic |
publisher |
Copernicus Publications |
publishDate |
2010 |
url |
https://doi.org/10.5194/os-6-621-2010 https://doaj.org/article/ee4ac5681d274baa81cc895641f91ea8 |
genre |
North Atlantic |
genre_facet |
North Atlantic |
op_source |
Ocean Science, Vol 6, Iss 3, Pp 621-631 (2010) |
op_relation |
http://www.ocean-sci.net/6/621/2010/os-6-621-2010.pdf https://doaj.org/toc/1812-0784 https://doaj.org/toc/1812-0792 doi:10.5194/os-6-621-2010 1812-0784 1812-0792 https://doaj.org/article/ee4ac5681d274baa81cc895641f91ea8 |
op_doi |
https://doi.org/10.5194/os-6-621-2010 |
container_title |
Ocean Science |
container_volume |
6 |
container_issue |
3 |
container_start_page |
621 |
op_container_end_page |
631 |
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1766128355561701376 |