High frequency variability of the Atlantic meridional overturning circulation
We compare the variability of the Atlantic meridional overturning circulation (AMOC) as simulated by the coupled climate models of the RAPID project, which cover a wide range of resolution and complexity, and observed by the RAPID/MOCHA array at about 26N. We analyse variability on a range of timesc...
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European Geosciences Union
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ftunivreading:oai:centaur.reading.ac.uk:21211 2024-09-15T18:24:19+00:00 High frequency variability of the Atlantic meridional overturning circulation Balan Sarojini, Beena Gregory, Jonathan Tailleux, Remi Bigg, G.R. Blaker, A.T. Cameron, D.R. Edwards, N.R. Megann, A.P. Shaffrey, Len Sinha, B. 2011 text https://centaur.reading.ac.uk/21211/ https://centaur.reading.ac.uk/21211/1/hfv_040711_bbs.pdf en eng European Geosciences Union https://centaur.reading.ac.uk/21211/1/hfv_040711_bbs.pdf Balan Sarojini, B. <https://centaur.reading.ac.uk/view/creators/90000966.html>, Gregory, J. <https://centaur.reading.ac.uk/view/creators/90000874.html> orcid:0000-0003-1296-8644 , Tailleux, R. <https://centaur.reading.ac.uk/view/creators/90000948.html> orcid:0000-0001-8998-9107 , Bigg, G.R., Blaker, A.T., Cameron, D.R., Edwards, N.R., Megann, A.P., Shaffrey, L. <https://centaur.reading.ac.uk/view/creators/90000111.html> orcid:0000-0003-2696-752X and Sinha, B. (2011) High frequency variability of the Atlantic meridional overturning circulation. Ocean Science, 7 (4). pp. 471-486. ISSN 1812-0784 doi: https://doi.org/10.5194/os-7-471-2011 <https://doi.org/10.5194/os-7-471-2011> Article PeerReviewed 2011 ftunivreading https://doi.org/10.5194/os-7-471-2011 2024-06-25T14:49:32Z We compare the variability of the Atlantic meridional overturning circulation (AMOC) as simulated by the coupled climate models of the RAPID project, which cover a wide range of resolution and complexity, and observed by the RAPID/MOCHA array at about 26N. We analyse variability on a range of timescales, from five-daily to interannual. In models of all resolutions there is substantial variability on timescales of a few days; in most AOGCMs the amplitude of the variability is of somewhat larger magnitude than that observed by the RAPID array, while the time-mean is within about 10% of the observational estimate. The amplitude of the simulated annual cycle is similar to observations, but the shape of the annual cycle shows a spread among the models. A dynamical decomposition shows that in the models, as in observations, the AMOC is predominantly geostrophic (driven by pressure and sea-level gradients), with both geostrophic and Ekman contributions to variability, the latter being exaggerated and the former underrepresented in models. Other ageostrophic terms, neglected in the observational estimate, are small but not negligible. The time-mean of the western boundary current near the latitude of the RAPID/MOCHA array has a much wider model spread than the AMOC does, indicating large differences among models in the simulation of the wind-driven gyre circulation, and its variability is unrealistically small in the models. In many RAPID models and in models of the Coupled Model Intercomparison Project Phase 3 (CMIP3), interannual variability of the maximum of the AMOC wherever it lies, which is a commonly used model index, is similar to interannual variability in the AMOC at 26N. Annual volume and heat transport timeseries at the same latitude are well-correlated within 15--45N, indicating the climatic importance of the AMOC. In the RAPID and CMIP3 models, we show that the AMOC is correlated over considerable distances in latitude, but not the whole extent of the north Atlantic; consequently interannual variability of ... Article in Journal/Newspaper North Atlantic CentAUR: Central Archive at the University of Reading Ocean Science 7 4 471 486 |
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Open Polar |
collection |
CentAUR: Central Archive at the University of Reading |
op_collection_id |
ftunivreading |
language |
English |
description |
We compare the variability of the Atlantic meridional overturning circulation (AMOC) as simulated by the coupled climate models of the RAPID project, which cover a wide range of resolution and complexity, and observed by the RAPID/MOCHA array at about 26N. We analyse variability on a range of timescales, from five-daily to interannual. In models of all resolutions there is substantial variability on timescales of a few days; in most AOGCMs the amplitude of the variability is of somewhat larger magnitude than that observed by the RAPID array, while the time-mean is within about 10% of the observational estimate. The amplitude of the simulated annual cycle is similar to observations, but the shape of the annual cycle shows a spread among the models. A dynamical decomposition shows that in the models, as in observations, the AMOC is predominantly geostrophic (driven by pressure and sea-level gradients), with both geostrophic and Ekman contributions to variability, the latter being exaggerated and the former underrepresented in models. Other ageostrophic terms, neglected in the observational estimate, are small but not negligible. The time-mean of the western boundary current near the latitude of the RAPID/MOCHA array has a much wider model spread than the AMOC does, indicating large differences among models in the simulation of the wind-driven gyre circulation, and its variability is unrealistically small in the models. In many RAPID models and in models of the Coupled Model Intercomparison Project Phase 3 (CMIP3), interannual variability of the maximum of the AMOC wherever it lies, which is a commonly used model index, is similar to interannual variability in the AMOC at 26N. Annual volume and heat transport timeseries at the same latitude are well-correlated within 15--45N, indicating the climatic importance of the AMOC. In the RAPID and CMIP3 models, we show that the AMOC is correlated over considerable distances in latitude, but not the whole extent of the north Atlantic; consequently interannual variability of ... |
format |
Article in Journal/Newspaper |
author |
Balan Sarojini, Beena Gregory, Jonathan Tailleux, Remi Bigg, G.R. Blaker, A.T. Cameron, D.R. Edwards, N.R. Megann, A.P. Shaffrey, Len Sinha, B. |
spellingShingle |
Balan Sarojini, Beena Gregory, Jonathan Tailleux, Remi Bigg, G.R. Blaker, A.T. Cameron, D.R. Edwards, N.R. Megann, A.P. Shaffrey, Len Sinha, B. High frequency variability of the Atlantic meridional overturning circulation |
author_facet |
Balan Sarojini, Beena Gregory, Jonathan Tailleux, Remi Bigg, G.R. Blaker, A.T. Cameron, D.R. Edwards, N.R. Megann, A.P. Shaffrey, Len Sinha, B. |
author_sort |
Balan Sarojini, Beena |
title |
High frequency variability of the Atlantic meridional overturning circulation |
title_short |
High frequency variability of the Atlantic meridional overturning circulation |
title_full |
High frequency variability of the Atlantic meridional overturning circulation |
title_fullStr |
High frequency variability of the Atlantic meridional overturning circulation |
title_full_unstemmed |
High frequency variability of the Atlantic meridional overturning circulation |
title_sort |
high frequency variability of the atlantic meridional overturning circulation |
publisher |
European Geosciences Union |
publishDate |
2011 |
url |
https://centaur.reading.ac.uk/21211/ https://centaur.reading.ac.uk/21211/1/hfv_040711_bbs.pdf |
genre |
North Atlantic |
genre_facet |
North Atlantic |
op_relation |
https://centaur.reading.ac.uk/21211/1/hfv_040711_bbs.pdf Balan Sarojini, B. <https://centaur.reading.ac.uk/view/creators/90000966.html>, Gregory, J. <https://centaur.reading.ac.uk/view/creators/90000874.html> orcid:0000-0003-1296-8644 , Tailleux, R. <https://centaur.reading.ac.uk/view/creators/90000948.html> orcid:0000-0001-8998-9107 , Bigg, G.R., Blaker, A.T., Cameron, D.R., Edwards, N.R., Megann, A.P., Shaffrey, L. <https://centaur.reading.ac.uk/view/creators/90000111.html> orcid:0000-0003-2696-752X and Sinha, B. (2011) High frequency variability of the Atlantic meridional overturning circulation. Ocean Science, 7 (4). pp. 471-486. ISSN 1812-0784 doi: https://doi.org/10.5194/os-7-471-2011 <https://doi.org/10.5194/os-7-471-2011> |
op_doi |
https://doi.org/10.5194/os-7-471-2011 |
container_title |
Ocean Science |
container_volume |
7 |
container_issue |
4 |
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471 |
op_container_end_page |
486 |
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1810464641384448000 |