Depth dependence of westward-propagating North Atlantic features diagnosed from altimetry and a numerical 1/6° model
A 1/6° numerical simulation is used to investigate the vertical structure of westward propagation between 1993 and 2000 in the North Atlantic ocean. The realism of the simulated westward propagating signals, interpreted principally as the signature of first-mode baroclinic Rossby waves (RW), is firs...
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Language: | English |
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Copernicus Publications
2008
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ftnonlinearchiv:oai:noa.gwlb.de:cop_mods_00031697 2023-05-15T17:31:31+02:00 Depth dependence of westward-propagating North Atlantic features diagnosed from altimetry and a numerical 1/6° model Lecointre, A. Penduff, T. Cipollini, P. Tailleux, R. Barnier, B. 2008-03 electronic https://doi.org/10.5194/os-4-99-2008 https://noa.gwlb.de/receive/cop_mods_00031697 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00031651/os-4-99-2008.pdf https://os.copernicus.org/articles/4/99/2008/os-4-99-2008.pdf eng eng Copernicus Publications Ocean Science -- http://www.bibliothek.uni-regensburg.de/ezeit/?2183769 -- http://www.copernicus.org/EGU/os/os.html -- 1812-0792 https://doi.org/10.5194/os-4-99-2008 https://noa.gwlb.de/receive/cop_mods_00031697 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00031651/os-4-99-2008.pdf https://os.copernicus.org/articles/4/99/2008/os-4-99-2008.pdf uneingeschränkt info:eu-repo/semantics/openAccess article Verlagsveröffentlichung article Text doc-type:article 2008 ftnonlinearchiv https://doi.org/10.5194/os-4-99-2008 2022-02-08T22:46:37Z A 1/6° numerical simulation is used to investigate the vertical structure of westward propagation between 1993 and 2000 in the North Atlantic ocean. The realism of the simulated westward propagating signals, interpreted principally as the signature of first-mode baroclinic Rossby waves (RW), is first assessed by comparing the simulated amplitude and zonal phase speeds of Sea Level Anomalies (SLA) against TOPEX/Poseidon-ERS satellite altimeter data. Then, the (unobserved) subsurface signature of RW phase speeds is investigated from model outputs by means of the Radon Transform which was specifically adapted to focus on first-mode baroclinic RW. The analysis is performed on observed and simulated SLA and along 9 simulated isopycnal displacements spanning the 0–3250 m depth range. Simulated RW phase speeds agree well with their observed counterparts at the surface, although with a slight slow bias. Below the surface, the simulated phase speeds exhibit a systematic deceleration with increasing depth, by a factor that appears to vary geographically. Thus, while the reduction factor is about 15–18% on average at 3250 m over the region considered, it appears to be much weaker (about 5–8%) in the eddy-active Azores Current, where westward propagating structures might be more coherent in the vertical. In the context of linear theories, these results question the often-made normal mode assumption of many WKB-based theories that the phase speed is independent of depth. Alternatively, these results could also suggest that the vertical structure of westward propagating signals may significantly depend on their degree of nonlinearity, with the degree of vertical coherence possibly increasing with the degree of nonlinearity. Article in Journal/Newspaper North Atlantic Niedersächsisches Online-Archiv NOA Ocean Science 4 1 99 113 |
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Open Polar |
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Niedersächsisches Online-Archiv NOA |
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English |
topic |
article Verlagsveröffentlichung |
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article Verlagsveröffentlichung Lecointre, A. Penduff, T. Cipollini, P. Tailleux, R. Barnier, B. Depth dependence of westward-propagating North Atlantic features diagnosed from altimetry and a numerical 1/6° model |
topic_facet |
article Verlagsveröffentlichung |
description |
A 1/6° numerical simulation is used to investigate the vertical structure of westward propagation between 1993 and 2000 in the North Atlantic ocean. The realism of the simulated westward propagating signals, interpreted principally as the signature of first-mode baroclinic Rossby waves (RW), is first assessed by comparing the simulated amplitude and zonal phase speeds of Sea Level Anomalies (SLA) against TOPEX/Poseidon-ERS satellite altimeter data. Then, the (unobserved) subsurface signature of RW phase speeds is investigated from model outputs by means of the Radon Transform which was specifically adapted to focus on first-mode baroclinic RW. The analysis is performed on observed and simulated SLA and along 9 simulated isopycnal displacements spanning the 0–3250 m depth range. Simulated RW phase speeds agree well with their observed counterparts at the surface, although with a slight slow bias. Below the surface, the simulated phase speeds exhibit a systematic deceleration with increasing depth, by a factor that appears to vary geographically. Thus, while the reduction factor is about 15–18% on average at 3250 m over the region considered, it appears to be much weaker (about 5–8%) in the eddy-active Azores Current, where westward propagating structures might be more coherent in the vertical. In the context of linear theories, these results question the often-made normal mode assumption of many WKB-based theories that the phase speed is independent of depth. Alternatively, these results could also suggest that the vertical structure of westward propagating signals may significantly depend on their degree of nonlinearity, with the degree of vertical coherence possibly increasing with the degree of nonlinearity. |
format |
Article in Journal/Newspaper |
author |
Lecointre, A. Penduff, T. Cipollini, P. Tailleux, R. Barnier, B. |
author_facet |
Lecointre, A. Penduff, T. Cipollini, P. Tailleux, R. Barnier, B. |
author_sort |
Lecointre, A. |
title |
Depth dependence of westward-propagating North Atlantic features diagnosed from altimetry and a numerical 1/6° model |
title_short |
Depth dependence of westward-propagating North Atlantic features diagnosed from altimetry and a numerical 1/6° model |
title_full |
Depth dependence of westward-propagating North Atlantic features diagnosed from altimetry and a numerical 1/6° model |
title_fullStr |
Depth dependence of westward-propagating North Atlantic features diagnosed from altimetry and a numerical 1/6° model |
title_full_unstemmed |
Depth dependence of westward-propagating North Atlantic features diagnosed from altimetry and a numerical 1/6° model |
title_sort |
depth dependence of westward-propagating north atlantic features diagnosed from altimetry and a numerical 1/6° model |
publisher |
Copernicus Publications |
publishDate |
2008 |
url |
https://doi.org/10.5194/os-4-99-2008 https://noa.gwlb.de/receive/cop_mods_00031697 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00031651/os-4-99-2008.pdf https://os.copernicus.org/articles/4/99/2008/os-4-99-2008.pdf |
genre |
North Atlantic |
genre_facet |
North Atlantic |
op_relation |
Ocean Science -- http://www.bibliothek.uni-regensburg.de/ezeit/?2183769 -- http://www.copernicus.org/EGU/os/os.html -- 1812-0792 https://doi.org/10.5194/os-4-99-2008 https://noa.gwlb.de/receive/cop_mods_00031697 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00031651/os-4-99-2008.pdf https://os.copernicus.org/articles/4/99/2008/os-4-99-2008.pdf |
op_rights |
uneingeschränkt info:eu-repo/semantics/openAccess |
op_doi |
https://doi.org/10.5194/os-4-99-2008 |
container_title |
Ocean Science |
container_volume |
4 |
container_issue |
1 |
container_start_page |
99 |
op_container_end_page |
113 |
_version_ |
1766129156790157312 |