Two Stable Equilibria of the Atlantic Subpolar Gyre
The cyclonic circulation of the Atlantic subpolar gyre is a key mechanism for North Atlantic climate variability on a wide range of time scales. It is generally accepted that it is driven by both cyclonic winds and buoyancy forcing, yet the individual importance and dynamical interactions of the two...
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2014
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ftdatacite:10.48350/47327 2023-05-15T17:06:09+02:00 Two Stable Equilibria of the Atlantic Subpolar Gyre Born, Andreas Stocker, Thomas F. 2014 https://dx.doi.org/10.48350/47327 https://boris.unibe.ch/47327/ unknown American Meteorological Society https://dx.doi.org/10.1175/JPO-D-13-073.1 open access publisher holds copyright http://purl.org/coar/access_right/c_abf2 530 Physics journal article article-journal Text ScholarlyArticle 2014 ftdatacite https://doi.org/10.48350/47327 https://doi.org/10.1175/JPO-D-13-073.1 2022-02-08T16:39:48Z The cyclonic circulation of the Atlantic subpolar gyre is a key mechanism for North Atlantic climate variability on a wide range of time scales. It is generally accepted that it is driven by both cyclonic winds and buoyancy forcing, yet the individual importance and dynamical interactions of the two contributions remain unclear. The authors propose a simplified four-box model representing the convective basin of the Labrador Sea and its shallow and deep boundary current system, the western subpolar gyre. Convective heat loss drives a baroclinic flow of relatively light water around the dense center. Eddy salt flux from the boundary current to the center increases with a stronger circulation, favors the formation of dense waters, and thereby sustains a strong baroclinic flow, approximately 10%–25% of the total. In contrast, when the baroclinic flow is not active, surface waters may be too fresh to convect, and a buoyancy-driven circulation cannot develop. This situation corresponds to a second stable circulation mode. A hysteresis is found for variations in surface freshwater flux and the salinity of the near-surface boundary current. An analytical solution is presented and analyzed. Text Labrador Sea North Atlantic DataCite Metadata Store (German National Library of Science and Technology) |
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530 Physics |
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530 Physics Born, Andreas Stocker, Thomas F. Two Stable Equilibria of the Atlantic Subpolar Gyre |
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530 Physics |
description |
The cyclonic circulation of the Atlantic subpolar gyre is a key mechanism for North Atlantic climate variability on a wide range of time scales. It is generally accepted that it is driven by both cyclonic winds and buoyancy forcing, yet the individual importance and dynamical interactions of the two contributions remain unclear. The authors propose a simplified four-box model representing the convective basin of the Labrador Sea and its shallow and deep boundary current system, the western subpolar gyre. Convective heat loss drives a baroclinic flow of relatively light water around the dense center. Eddy salt flux from the boundary current to the center increases with a stronger circulation, favors the formation of dense waters, and thereby sustains a strong baroclinic flow, approximately 10%–25% of the total. In contrast, when the baroclinic flow is not active, surface waters may be too fresh to convect, and a buoyancy-driven circulation cannot develop. This situation corresponds to a second stable circulation mode. A hysteresis is found for variations in surface freshwater flux and the salinity of the near-surface boundary current. An analytical solution is presented and analyzed. |
format |
Text |
author |
Born, Andreas Stocker, Thomas F. |
author_facet |
Born, Andreas Stocker, Thomas F. |
author_sort |
Born, Andreas |
title |
Two Stable Equilibria of the Atlantic Subpolar Gyre |
title_short |
Two Stable Equilibria of the Atlantic Subpolar Gyre |
title_full |
Two Stable Equilibria of the Atlantic Subpolar Gyre |
title_fullStr |
Two Stable Equilibria of the Atlantic Subpolar Gyre |
title_full_unstemmed |
Two Stable Equilibria of the Atlantic Subpolar Gyre |
title_sort |
two stable equilibria of the atlantic subpolar gyre |
publisher |
American Meteorological Society |
publishDate |
2014 |
url |
https://dx.doi.org/10.48350/47327 https://boris.unibe.ch/47327/ |
genre |
Labrador Sea North Atlantic |
genre_facet |
Labrador Sea North Atlantic |
op_relation |
https://dx.doi.org/10.1175/JPO-D-13-073.1 |
op_rights |
open access publisher holds copyright http://purl.org/coar/access_right/c_abf2 |
op_doi |
https://doi.org/10.48350/47327 https://doi.org/10.1175/JPO-D-13-073.1 |
_version_ |
1766061162521165824 |