Optimal nonlinear excitation of decadal variability of the North Atlantic thermohaline circulation
Nonlinear development of salinity perturbations in the Atlantic thermohaline circulation (THC) is investigated with a three-dimensional ocean circulation model, using the conditional nonlinear optimal perturbation method. The results show two types of optimal initial perturbations of sea surface sal...
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ftunivutrecht:oai:dspace.library.uu.nl:1874/290646 2023-07-23T04:20:40+02:00 Optimal nonlinear excitation of decadal variability of the North Atlantic thermohaline circulation Ziqing, Z. Mu, M. Dijkstra, H.A. Marine and Atmospheric Research Sub Physical Oceanography 2013 application/pdf https://dspace.library.uu.nl/handle/1874/290646 en eng 1993-5005 https://dspace.library.uu.nl/handle/1874/290646 info:eu-repo/semantics/EmbargoedAccess Article 2013 ftunivutrecht 2023-07-02T00:51:57Z Nonlinear development of salinity perturbations in the Atlantic thermohaline circulation (THC) is investigated with a three-dimensional ocean circulation model, using the conditional nonlinear optimal perturbation method. The results show two types of optimal initial perturbations of sea surface salinity, one associated with freshwater and the other with salinity. Both types of perturbations excite decadal variability of the THC. Under the same amplitude of initial perturbation, the decadal variation induced by the freshwater perturbation is much stronger than that by the salinity perturbation, suggesting that the THC is more sensitive to freshwater than salinity perturbation. As the amplitude of initial perturbation increases, the decadal variations become stronger for both perturbations. For salinity perturbations, recovery time of the THC to return to steady state gradually saturates with increasing amplitude, whereas this recovery time increases remarkably for freshwater perturbations. A nonlinear (advective) feedback between density and velocity anomalies is proposed to explain these characteristics of decadal variability excitation. The results are consistent with previous ones from simple box models, and highlight the importance of nonlinear feedback in decadal THC variability. Article in Journal/Newspaper North Atlantic North atlantic Thermohaline circulation Utrecht University Repository |
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Open Polar |
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Utrecht University Repository |
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ftunivutrecht |
language |
English |
description |
Nonlinear development of salinity perturbations in the Atlantic thermohaline circulation (THC) is investigated with a three-dimensional ocean circulation model, using the conditional nonlinear optimal perturbation method. The results show two types of optimal initial perturbations of sea surface salinity, one associated with freshwater and the other with salinity. Both types of perturbations excite decadal variability of the THC. Under the same amplitude of initial perturbation, the decadal variation induced by the freshwater perturbation is much stronger than that by the salinity perturbation, suggesting that the THC is more sensitive to freshwater than salinity perturbation. As the amplitude of initial perturbation increases, the decadal variations become stronger for both perturbations. For salinity perturbations, recovery time of the THC to return to steady state gradually saturates with increasing amplitude, whereas this recovery time increases remarkably for freshwater perturbations. A nonlinear (advective) feedback between density and velocity anomalies is proposed to explain these characteristics of decadal variability excitation. The results are consistent with previous ones from simple box models, and highlight the importance of nonlinear feedback in decadal THC variability. |
author2 |
Marine and Atmospheric Research Sub Physical Oceanography |
format |
Article in Journal/Newspaper |
author |
Ziqing, Z. Mu, M. Dijkstra, H.A. |
spellingShingle |
Ziqing, Z. Mu, M. Dijkstra, H.A. Optimal nonlinear excitation of decadal variability of the North Atlantic thermohaline circulation |
author_facet |
Ziqing, Z. Mu, M. Dijkstra, H.A. |
author_sort |
Ziqing, Z. |
title |
Optimal nonlinear excitation of decadal variability of the North Atlantic thermohaline circulation |
title_short |
Optimal nonlinear excitation of decadal variability of the North Atlantic thermohaline circulation |
title_full |
Optimal nonlinear excitation of decadal variability of the North Atlantic thermohaline circulation |
title_fullStr |
Optimal nonlinear excitation of decadal variability of the North Atlantic thermohaline circulation |
title_full_unstemmed |
Optimal nonlinear excitation of decadal variability of the North Atlantic thermohaline circulation |
title_sort |
optimal nonlinear excitation of decadal variability of the north atlantic thermohaline circulation |
publishDate |
2013 |
url |
https://dspace.library.uu.nl/handle/1874/290646 |
genre |
North Atlantic North atlantic Thermohaline circulation |
genre_facet |
North Atlantic North atlantic Thermohaline circulation |
op_relation |
1993-5005 https://dspace.library.uu.nl/handle/1874/290646 |
op_rights |
info:eu-repo/semantics/EmbargoedAccess |
_version_ |
1772185265076436992 |