Abrupt millennial variability and interdecadal-interstadial oscillations in a global coupled model: sensitivity to the background climate state
Abstract The origin and bifurcation structure of abrupt millennial-scale climate transitions under steady external solar forcing and in the absence of atmospheric synoptic variability is studied by means of a global coupled model of intermediate complexity. We show that the origin of Dansgaard-Oesch...
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ftciteseerx:oai:CiteSeerX.psu:10.1.1.1045.4658 2023-05-15T17:31:07+02:00 Abrupt millennial variability and interdecadal-interstadial oscillations in a global coupled model: sensitivity to the background climate state Olivier Arzel Matthew H England Alain Colin De Verdière Thierry Huck The Pennsylvania State University CiteSeerX Archives application/pdf http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.1045.4658 http://www.ifremer.fr/lpo/thuck/publis/Arzel_et_al_CD2012.pdf en eng http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.1045.4658 http://www.ifremer.fr/lpo/thuck/publis/Arzel_et_al_CD2012.pdf Metadata may be used without restrictions as long as the oai identifier remains attached to it. http://www.ifremer.fr/lpo/thuck/publis/Arzel_et_al_CD2012.pdf text ftciteseerx 2020-04-05T00:17:47Z Abstract The origin and bifurcation structure of abrupt millennial-scale climate transitions under steady external solar forcing and in the absence of atmospheric synoptic variability is studied by means of a global coupled model of intermediate complexity. We show that the origin of Dansgaard-Oeschger type oscillations in the model is caused by the weaker northward oceanic heat transport in the Atlantic basin. This is in agreement with previous studies realized with much simpler models, based on highly idealized geometries and simplified physics. The existence of abrupt millennial-scale climate transitions during glacial times can therefore be interpreted as a consequence of the weakening of the negative temperature-advection feedback. This is confirmed through a series of numerical experiments designed to explore the sensitivity of the bifurcation structure of the Atlantic meridional overturning circulation to increased atmospheric CO 2 levels under glacial boundary conditions. Contrasting with the cold, stadial, phases of millennial oscillations, we also show the emergence of strong interdecadal variability in the North Atlantic sector during warm interstadials. The instability driving these interdecadal-interstadial oscillations is shown to be identical to that found in ocean-only models forced by fixed surface buoyancy fluxes, that is, a large-scale baroclinic instability developing in the vicinity of the western boundary current in the North Atlantic. Comparisons with modern observations further suggest a physical mechanism similar to that driving the 30-40 years time scale associated with the Atlantic multidecadal oscillation. Text North Atlantic Unknown |
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English |
description |
Abstract The origin and bifurcation structure of abrupt millennial-scale climate transitions under steady external solar forcing and in the absence of atmospheric synoptic variability is studied by means of a global coupled model of intermediate complexity. We show that the origin of Dansgaard-Oeschger type oscillations in the model is caused by the weaker northward oceanic heat transport in the Atlantic basin. This is in agreement with previous studies realized with much simpler models, based on highly idealized geometries and simplified physics. The existence of abrupt millennial-scale climate transitions during glacial times can therefore be interpreted as a consequence of the weakening of the negative temperature-advection feedback. This is confirmed through a series of numerical experiments designed to explore the sensitivity of the bifurcation structure of the Atlantic meridional overturning circulation to increased atmospheric CO 2 levels under glacial boundary conditions. Contrasting with the cold, stadial, phases of millennial oscillations, we also show the emergence of strong interdecadal variability in the North Atlantic sector during warm interstadials. The instability driving these interdecadal-interstadial oscillations is shown to be identical to that found in ocean-only models forced by fixed surface buoyancy fluxes, that is, a large-scale baroclinic instability developing in the vicinity of the western boundary current in the North Atlantic. Comparisons with modern observations further suggest a physical mechanism similar to that driving the 30-40 years time scale associated with the Atlantic multidecadal oscillation. |
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The Pennsylvania State University CiteSeerX Archives |
format |
Text |
author |
Olivier Arzel Matthew H England Alain Colin De Verdière Thierry Huck |
spellingShingle |
Olivier Arzel Matthew H England Alain Colin De Verdière Thierry Huck Abrupt millennial variability and interdecadal-interstadial oscillations in a global coupled model: sensitivity to the background climate state |
author_facet |
Olivier Arzel Matthew H England Alain Colin De Verdière Thierry Huck |
author_sort |
Olivier Arzel |
title |
Abrupt millennial variability and interdecadal-interstadial oscillations in a global coupled model: sensitivity to the background climate state |
title_short |
Abrupt millennial variability and interdecadal-interstadial oscillations in a global coupled model: sensitivity to the background climate state |
title_full |
Abrupt millennial variability and interdecadal-interstadial oscillations in a global coupled model: sensitivity to the background climate state |
title_fullStr |
Abrupt millennial variability and interdecadal-interstadial oscillations in a global coupled model: sensitivity to the background climate state |
title_full_unstemmed |
Abrupt millennial variability and interdecadal-interstadial oscillations in a global coupled model: sensitivity to the background climate state |
title_sort |
abrupt millennial variability and interdecadal-interstadial oscillations in a global coupled model: sensitivity to the background climate state |
url |
http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.1045.4658 http://www.ifremer.fr/lpo/thuck/publis/Arzel_et_al_CD2012.pdf |
genre |
North Atlantic |
genre_facet |
North Atlantic |
op_source |
http://www.ifremer.fr/lpo/thuck/publis/Arzel_et_al_CD2012.pdf |
op_relation |
http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.1045.4658 http://www.ifremer.fr/lpo/thuck/publis/Arzel_et_al_CD2012.pdf |
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Metadata may be used without restrictions as long as the oai identifier remains attached to it. |
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1766128445945806848 |