Fast mechanisms linking the Labrador Sea with subtropical Atlantic overturning
We use an ocean general circulation model and its adjoint to analyze the causal chain linking sea surface buoyancy anomalies in the Labrador Sea to variability in the deep branch of the Atlantic meridional overturning circulation (AMOC) on inter-annual timescales. Our study highlights the importance...
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Online Access: | https://doi.org/10.1007/s00382-022-06459-y https://ora.ox.ac.uk/objects/uuid:3d15b612-5cbe-424c-9bd7-424c0cc85981 |
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ftuloxford:oai:ora.ox.ac.uk:uuid:3d15b612-5cbe-424c-9bd7-424c0cc85981 2023-06-11T04:13:46+02:00 Fast mechanisms linking the Labrador Sea with subtropical Atlantic overturning Kostov, Y Messias, M-J Mercier, H Johnson, HL Marshall, DP 2022-10-28 https://doi.org/10.1007/s00382-022-06459-y https://ora.ox.ac.uk/objects/uuid:3d15b612-5cbe-424c-9bd7-424c0cc85981 eng eng Springer doi:10.1007/s00382-022-06459-y https://ora.ox.ac.uk/objects/uuid:3d15b612-5cbe-424c-9bd7-424c0cc85981 https://doi.org/10.1007/s00382-022-06459-y info:eu-repo/semantics/openAccess CC Attribution (CC BY) Journal article 2022 ftuloxford https://doi.org/10.1007/s00382-022-06459-y 2023-04-27T22:06:14Z We use an ocean general circulation model and its adjoint to analyze the causal chain linking sea surface buoyancy anomalies in the Labrador Sea to variability in the deep branch of the Atlantic meridional overturning circulation (AMOC) on inter-annual timescales. Our study highlights the importance of the North Atlantic Current (NAC) for the north-to-south connectivity in the AMOC and for the meridional transport of Lower North Atlantic Deep Water (LNADW). We identify two mechanisms that allow the Labrador Sea to impact velocities in the LNADW layer. The first mechanism involves a passive advection of surface buoyancy anomalies from the Labrador Sea towards the eastern subpolar gyre by the background NAC. The second mechanism plays a dominant role and involves a dynamical response of the NAC to surface density anomalies originating in the Labrador Sea; the NAC adjustment modifies the northward transport of salt and heat and exerts a strong positive feedback, amplifying the upper ocean buoyancy anomalies. The two mechanisms spin up/down the subpolar gyre on a timescale of years, while boundary trapped waves rapidly communicate this signal to the subtropics and trigger an adjustment of LNADW transport on a timescale of months. The NAC and the eastern subpolar gyre play an essential role in both mechanisms linking the Labrador Sea with LNADW transport variability and the subtropical AMOC. We thus reconcile two apparently contradictory paradigms about AMOC connectivity: (1) Labrador Sea buoyancy anomalies drive AMOC variability; (2) water mass transformation is largest in the eastern subpolar gyre. Article in Journal/Newspaper Labrador Sea north atlantic current North Atlantic Deep Water North Atlantic ORA - Oxford University Research Archive Climate Dynamics |
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Open Polar |
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ORA - Oxford University Research Archive |
op_collection_id |
ftuloxford |
language |
English |
description |
We use an ocean general circulation model and its adjoint to analyze the causal chain linking sea surface buoyancy anomalies in the Labrador Sea to variability in the deep branch of the Atlantic meridional overturning circulation (AMOC) on inter-annual timescales. Our study highlights the importance of the North Atlantic Current (NAC) for the north-to-south connectivity in the AMOC and for the meridional transport of Lower North Atlantic Deep Water (LNADW). We identify two mechanisms that allow the Labrador Sea to impact velocities in the LNADW layer. The first mechanism involves a passive advection of surface buoyancy anomalies from the Labrador Sea towards the eastern subpolar gyre by the background NAC. The second mechanism plays a dominant role and involves a dynamical response of the NAC to surface density anomalies originating in the Labrador Sea; the NAC adjustment modifies the northward transport of salt and heat and exerts a strong positive feedback, amplifying the upper ocean buoyancy anomalies. The two mechanisms spin up/down the subpolar gyre on a timescale of years, while boundary trapped waves rapidly communicate this signal to the subtropics and trigger an adjustment of LNADW transport on a timescale of months. The NAC and the eastern subpolar gyre play an essential role in both mechanisms linking the Labrador Sea with LNADW transport variability and the subtropical AMOC. We thus reconcile two apparently contradictory paradigms about AMOC connectivity: (1) Labrador Sea buoyancy anomalies drive AMOC variability; (2) water mass transformation is largest in the eastern subpolar gyre. |
format |
Article in Journal/Newspaper |
author |
Kostov, Y Messias, M-J Mercier, H Johnson, HL Marshall, DP |
spellingShingle |
Kostov, Y Messias, M-J Mercier, H Johnson, HL Marshall, DP Fast mechanisms linking the Labrador Sea with subtropical Atlantic overturning |
author_facet |
Kostov, Y Messias, M-J Mercier, H Johnson, HL Marshall, DP |
author_sort |
Kostov, Y |
title |
Fast mechanisms linking the Labrador Sea with subtropical Atlantic overturning |
title_short |
Fast mechanisms linking the Labrador Sea with subtropical Atlantic overturning |
title_full |
Fast mechanisms linking the Labrador Sea with subtropical Atlantic overturning |
title_fullStr |
Fast mechanisms linking the Labrador Sea with subtropical Atlantic overturning |
title_full_unstemmed |
Fast mechanisms linking the Labrador Sea with subtropical Atlantic overturning |
title_sort |
fast mechanisms linking the labrador sea with subtropical atlantic overturning |
publisher |
Springer |
publishDate |
2022 |
url |
https://doi.org/10.1007/s00382-022-06459-y https://ora.ox.ac.uk/objects/uuid:3d15b612-5cbe-424c-9bd7-424c0cc85981 |
genre |
Labrador Sea north atlantic current North Atlantic Deep Water North Atlantic |
genre_facet |
Labrador Sea north atlantic current North Atlantic Deep Water North Atlantic |
op_relation |
doi:10.1007/s00382-022-06459-y https://ora.ox.ac.uk/objects/uuid:3d15b612-5cbe-424c-9bd7-424c0cc85981 https://doi.org/10.1007/s00382-022-06459-y |
op_rights |
info:eu-repo/semantics/openAccess CC Attribution (CC BY) |
op_doi |
https://doi.org/10.1007/s00382-022-06459-y |
container_title |
Climate Dynamics |
_version_ |
1768391107848175616 |