Temporal and spatial characteristics of sea surface height variability in the North Atlantic Ocean
We investigate the spatial and temporal variability of sea surface height (SSH) in the North Atlantic basin using satellite altimeter data from October 1992–January 2004. Our primary aim is to provide a detailed description of such variability, including that associated with propagating signals. We...
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Copernicus Publications
2006
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ftnonlinearchiv:oai:noa.gwlb.de:cop_mods_00032953 2023-05-15T17:06:15+02:00 Temporal and spatial characteristics of sea surface height variability in the North Atlantic Ocean Cromwell, D. 2006-10 electronic https://doi.org/10.5194/os-2-147-2006 https://noa.gwlb.de/receive/cop_mods_00032953 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00032907/os-2-147-2006.pdf https://os.copernicus.org/articles/2/147/2006/os-2-147-2006.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-2-147-2006 https://noa.gwlb.de/receive/cop_mods_00032953 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00032907/os-2-147-2006.pdf https://os.copernicus.org/articles/2/147/2006/os-2-147-2006.pdf https://open-access.net/ uneingeschränkt info:eu-repo/semantics/openAccess article Verlagsveröffentlichung article Text doc-type:article 2006 ftnonlinearchiv https://doi.org/10.5194/os-2-147-2006 2022-02-08T22:45:59Z We investigate the spatial and temporal variability of sea surface height (SSH) in the North Atlantic basin using satellite altimeter data from October 1992–January 2004. Our primary aim is to provide a detailed description of such variability, including that associated with propagating signals. We also investigate possible correlations between SSH variability and atmospheric pressure changes as represented by climate indices. We first investigate interannual SSH variations by deriving the complex empirical orthogonal functions (CEOFs) of altimeter data lowpass-filtered at 18 months. We determine the spatial structure of the leading four modes (both in amplitude and phase) and also the associated principal component (PC) time series. Using wavelet analysis we derive the time-varying spectral density of the PCs, revealing when particular modes were strongest between 1992–2004. The spatial pattern of the leading CEOF, comprising 30% of the total variability, displays a 5-year periodicity in phase; signal propagation is particularly marked in the Labrador Sea. The second mode, with a dominant 3-year signal, has strong variability in the eastern basin. Secondly, we focus on the Azores subtropical frontal zone. The leading mode (35%) is strong in the south and east of this region with strong variations at 3- and 5-year periods. The second mode (21%) has a near-zonal band of low variance between 22°–27° N, sandwiched between two regions of high variance. Thirdly, we lowpass filter the altimeter data at a cutoff of 30 days, instead of 18 months, in order to retain signals associated with propagating baroclinic Rossby waves and/or eddies. The leading mode is the annual steric signal, around 46% of the SSH variability. The third and fourth CEOFs, 11% of the remaining variability, are associated with westward propagation which is particularly dominant in a "waveband" between 32°–36° N. For all three cases considered above, no significant cross-correlation is found between the North Atlantic Oscillation index and the amplitude of the leading four PCs of interannual SSH variability. The only exception is an anti-correlation found over the North Atlantic basin between the NAO and the 4th PC. In the subtropical front, the East Atlantic Pattern index is anti-correlated with the leading PC for SSH variations lowpass filtered at 30 days. Further investigation of forcing mechanisms is suggested using hindcasts from ocean general circulation models. Article in Journal/Newspaper Labrador Sea North Atlantic North Atlantic oscillation Niedersächsisches Online-Archiv NOA Ocean Science 2 2 147 159 |
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article Verlagsveröffentlichung |
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article Verlagsveröffentlichung Cromwell, D. Temporal and spatial characteristics of sea surface height variability in the North Atlantic Ocean |
topic_facet |
article Verlagsveröffentlichung |
description |
We investigate the spatial and temporal variability of sea surface height (SSH) in the North Atlantic basin using satellite altimeter data from October 1992–January 2004. Our primary aim is to provide a detailed description of such variability, including that associated with propagating signals. We also investigate possible correlations between SSH variability and atmospheric pressure changes as represented by climate indices. We first investigate interannual SSH variations by deriving the complex empirical orthogonal functions (CEOFs) of altimeter data lowpass-filtered at 18 months. We determine the spatial structure of the leading four modes (both in amplitude and phase) and also the associated principal component (PC) time series. Using wavelet analysis we derive the time-varying spectral density of the PCs, revealing when particular modes were strongest between 1992–2004. The spatial pattern of the leading CEOF, comprising 30% of the total variability, displays a 5-year periodicity in phase; signal propagation is particularly marked in the Labrador Sea. The second mode, with a dominant 3-year signal, has strong variability in the eastern basin. Secondly, we focus on the Azores subtropical frontal zone. The leading mode (35%) is strong in the south and east of this region with strong variations at 3- and 5-year periods. The second mode (21%) has a near-zonal band of low variance between 22°–27° N, sandwiched between two regions of high variance. Thirdly, we lowpass filter the altimeter data at a cutoff of 30 days, instead of 18 months, in order to retain signals associated with propagating baroclinic Rossby waves and/or eddies. The leading mode is the annual steric signal, around 46% of the SSH variability. The third and fourth CEOFs, 11% of the remaining variability, are associated with westward propagation which is particularly dominant in a "waveband" between 32°–36° N. For all three cases considered above, no significant cross-correlation is found between the North Atlantic Oscillation index and the amplitude of the leading four PCs of interannual SSH variability. The only exception is an anti-correlation found over the North Atlantic basin between the NAO and the 4th PC. In the subtropical front, the East Atlantic Pattern index is anti-correlated with the leading PC for SSH variations lowpass filtered at 30 days. Further investigation of forcing mechanisms is suggested using hindcasts from ocean general circulation models. |
format |
Article in Journal/Newspaper |
author |
Cromwell, D. |
author_facet |
Cromwell, D. |
author_sort |
Cromwell, D. |
title |
Temporal and spatial characteristics of sea surface height variability in the North Atlantic Ocean |
title_short |
Temporal and spatial characteristics of sea surface height variability in the North Atlantic Ocean |
title_full |
Temporal and spatial characteristics of sea surface height variability in the North Atlantic Ocean |
title_fullStr |
Temporal and spatial characteristics of sea surface height variability in the North Atlantic Ocean |
title_full_unstemmed |
Temporal and spatial characteristics of sea surface height variability in the North Atlantic Ocean |
title_sort |
temporal and spatial characteristics of sea surface height variability in the north atlantic ocean |
publisher |
Copernicus Publications |
publishDate |
2006 |
url |
https://doi.org/10.5194/os-2-147-2006 https://noa.gwlb.de/receive/cop_mods_00032953 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00032907/os-2-147-2006.pdf https://os.copernicus.org/articles/2/147/2006/os-2-147-2006.pdf |
genre |
Labrador Sea North Atlantic North Atlantic oscillation |
genre_facet |
Labrador Sea North Atlantic North Atlantic oscillation |
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-2-147-2006 https://noa.gwlb.de/receive/cop_mods_00032953 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00032907/os-2-147-2006.pdf https://os.copernicus.org/articles/2/147/2006/os-2-147-2006.pdf |
op_rights |
https://open-access.net/ uneingeschränkt info:eu-repo/semantics/openAccess |
op_doi |
https://doi.org/10.5194/os-2-147-2006 |
container_title |
Ocean Science |
container_volume |
2 |
container_issue |
2 |
container_start_page |
147 |
op_container_end_page |
159 |
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1766061294979383296 |