Mixing and air–sea buoyancy fluxes set the time-mean overturning circulation in the subpolar North Atlantic and Nordic Seas
The overturning streamfunction as measured at the OSNAP (Overturning in the Subpolar North Atlantic Program) mooring array represents the transformation of warm, salty Atlantic Water into cold, fresh North Atlantic Deep Water (NADW). The magnitude of the overturning at the OSNAP array can therefore...
Published in: | Ocean Science |
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Copernicus Publications
2023
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Online Access: | https://doi.org/10.5194/os-19-745-2023 https://noa.gwlb.de/receive/cop_mods_00066824 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00065295/os-19-745-2023.pdf https://os.copernicus.org/articles/19/745/2023/os-19-745-2023.pdf |
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ftnonlinearchiv:oai:noa.gwlb.de:cop_mods_00066824 2023-06-18T03:40:58+02:00 Mixing and air–sea buoyancy fluxes set the time-mean overturning circulation in the subpolar North Atlantic and Nordic Seas Evans, Dafydd Gwyn Holliday, N. Penny Bacon, Sheldon Le Bras, Isabela 2023-06 electronic https://doi.org/10.5194/os-19-745-2023 https://noa.gwlb.de/receive/cop_mods_00066824 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00065295/os-19-745-2023.pdf https://os.copernicus.org/articles/19/745/2023/os-19-745-2023.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-19-745-2023 https://noa.gwlb.de/receive/cop_mods_00066824 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00065295/os-19-745-2023.pdf https://os.copernicus.org/articles/19/745/2023/os-19-745-2023.pdf https://creativecommons.org/licenses/by/4.0/ uneingeschränkt info:eu-repo/semantics/openAccess article Verlagsveröffentlichung article Text doc-type:article 2023 ftnonlinearchiv https://doi.org/10.5194/os-19-745-2023 2023-06-04T23:18:50Z The overturning streamfunction as measured at the OSNAP (Overturning in the Subpolar North Atlantic Program) mooring array represents the transformation of warm, salty Atlantic Water into cold, fresh North Atlantic Deep Water (NADW). The magnitude of the overturning at the OSNAP array can therefore be linked to the transformation by air–sea buoyancy fluxes and mixing in the region north of the OSNAP array. Here, we estimate these water mass transformations using observational-based, reanalysis-based and model-based datasets. Our results highlight that air–sea fluxes alone cannot account for the time-mean magnitude of the overturning at OSNAP, and therefore a residual mixing-driven transformation is required to explain the difference. A cooling by air–sea heat fluxes and a mixing-driven freshening in the Nordic Seas, Iceland Basin and Irminger Sea precondition the warm, salty Atlantic Water, forming subpolar mode water classes in the subpolar North Atlantic. Mixing in the interior of the Nordic Seas, over the Greenland–Scotland Ridge and along the boundaries of the Irminger Sea and Iceland Basin drive a water mass transformation that leads to the convergence of volume in the water mass classes associated with NADW. Air–sea buoyancy fluxes and mixing therefore play key and complementary roles in setting the magnitude of the overturning within the subpolar North Atlantic and Nordic Seas. This study highlights that, for ocean and climate models to realistically simulate the overturning circulation in the North Atlantic, the small-scale processes that lead to the mixing-driven formation of NADW must be adequately represented within the model's parameterisation scheme. Article in Journal/Newspaper Greenland Greenland-Scotland Ridge Iceland NADW Nordic Seas North Atlantic Deep Water North Atlantic Niedersächsisches Online-Archiv NOA Greenland Irminger Sea ENVELOPE(-34.041,-34.041,63.054,63.054) Ocean Science 19 3 745 768 |
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Open Polar |
collection |
Niedersächsisches Online-Archiv NOA |
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ftnonlinearchiv |
language |
English |
topic |
article Verlagsveröffentlichung |
spellingShingle |
article Verlagsveröffentlichung Evans, Dafydd Gwyn Holliday, N. Penny Bacon, Sheldon Le Bras, Isabela Mixing and air–sea buoyancy fluxes set the time-mean overturning circulation in the subpolar North Atlantic and Nordic Seas |
topic_facet |
article Verlagsveröffentlichung |
description |
The overturning streamfunction as measured at the OSNAP (Overturning in the Subpolar North Atlantic Program) mooring array represents the transformation of warm, salty Atlantic Water into cold, fresh North Atlantic Deep Water (NADW). The magnitude of the overturning at the OSNAP array can therefore be linked to the transformation by air–sea buoyancy fluxes and mixing in the region north of the OSNAP array. Here, we estimate these water mass transformations using observational-based, reanalysis-based and model-based datasets. Our results highlight that air–sea fluxes alone cannot account for the time-mean magnitude of the overturning at OSNAP, and therefore a residual mixing-driven transformation is required to explain the difference. A cooling by air–sea heat fluxes and a mixing-driven freshening in the Nordic Seas, Iceland Basin and Irminger Sea precondition the warm, salty Atlantic Water, forming subpolar mode water classes in the subpolar North Atlantic. Mixing in the interior of the Nordic Seas, over the Greenland–Scotland Ridge and along the boundaries of the Irminger Sea and Iceland Basin drive a water mass transformation that leads to the convergence of volume in the water mass classes associated with NADW. Air–sea buoyancy fluxes and mixing therefore play key and complementary roles in setting the magnitude of the overturning within the subpolar North Atlantic and Nordic Seas. This study highlights that, for ocean and climate models to realistically simulate the overturning circulation in the North Atlantic, the small-scale processes that lead to the mixing-driven formation of NADW must be adequately represented within the model's parameterisation scheme. |
format |
Article in Journal/Newspaper |
author |
Evans, Dafydd Gwyn Holliday, N. Penny Bacon, Sheldon Le Bras, Isabela |
author_facet |
Evans, Dafydd Gwyn Holliday, N. Penny Bacon, Sheldon Le Bras, Isabela |
author_sort |
Evans, Dafydd Gwyn |
title |
Mixing and air–sea buoyancy fluxes set the time-mean overturning circulation in the subpolar North Atlantic and Nordic Seas |
title_short |
Mixing and air–sea buoyancy fluxes set the time-mean overturning circulation in the subpolar North Atlantic and Nordic Seas |
title_full |
Mixing and air–sea buoyancy fluxes set the time-mean overturning circulation in the subpolar North Atlantic and Nordic Seas |
title_fullStr |
Mixing and air–sea buoyancy fluxes set the time-mean overturning circulation in the subpolar North Atlantic and Nordic Seas |
title_full_unstemmed |
Mixing and air–sea buoyancy fluxes set the time-mean overturning circulation in the subpolar North Atlantic and Nordic Seas |
title_sort |
mixing and air–sea buoyancy fluxes set the time-mean overturning circulation in the subpolar north atlantic and nordic seas |
publisher |
Copernicus Publications |
publishDate |
2023 |
url |
https://doi.org/10.5194/os-19-745-2023 https://noa.gwlb.de/receive/cop_mods_00066824 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00065295/os-19-745-2023.pdf https://os.copernicus.org/articles/19/745/2023/os-19-745-2023.pdf |
long_lat |
ENVELOPE(-34.041,-34.041,63.054,63.054) |
geographic |
Greenland Irminger Sea |
geographic_facet |
Greenland Irminger Sea |
genre |
Greenland Greenland-Scotland Ridge Iceland NADW Nordic Seas North Atlantic Deep Water North Atlantic |
genre_facet |
Greenland Greenland-Scotland Ridge Iceland NADW Nordic Seas North Atlantic Deep Water North Atlantic |
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-19-745-2023 https://noa.gwlb.de/receive/cop_mods_00066824 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00065295/os-19-745-2023.pdf https://os.copernicus.org/articles/19/745/2023/os-19-745-2023.pdf |
op_rights |
https://creativecommons.org/licenses/by/4.0/ uneingeschränkt info:eu-repo/semantics/openAccess |
op_doi |
https://doi.org/10.5194/os-19-745-2023 |
container_title |
Ocean Science |
container_volume |
19 |
container_issue |
3 |
container_start_page |
745 |
op_container_end_page |
768 |
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1769006333238968320 |