The mechanisms of the Atlantic meridional overturning circulation slowdown induced by Arctic sea ice decline
We explore the mechanisms by which Arctic sea ice decline affects the Atlantic meridional overturning circulation (AMOC) in a suite of numerical experiments perturbing the Arctic sea ice radiative budget within a fully coupled climate model. The imposed perturbations act to increase the amount of he...
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ftsouthampton:oai:eprints.soton.ac.uk:430591 2023-07-30T03:59:47+02:00 The mechanisms of the Atlantic meridional overturning circulation slowdown induced by Arctic sea ice decline Liu, Wei Fedorov, Alexey Sévellec, Florian 2019-02-01 https://eprints.soton.ac.uk/430591/ English eng Liu, Wei, Fedorov, Alexey and Sévellec, Florian (2019) The mechanisms of the Atlantic meridional overturning circulation slowdown induced by Arctic sea ice decline. Journal of Climate, 32 (4), 977-996. (doi:10.1175/JCLI-D-18-0231.1 <http://dx.doi.org/10.1175/JCLI-D-18-0231.1>). Article PeerReviewed 2019 ftsouthampton https://doi.org/10.1175/JCLI-D-18-0231.1 2023-07-09T22:29:25Z We explore the mechanisms by which Arctic sea ice decline affects the Atlantic meridional overturning circulation (AMOC) in a suite of numerical experiments perturbing the Arctic sea ice radiative budget within a fully coupled climate model. The imposed perturbations act to increase the amount of heat available to melt ice, leading to a rapid Arctic sea ice retreat within 5 years after the perturbations are activated. In response, the AMOC gradually weakens over the next ;100 years. The AMOC changes can be explained by the accumulation in the Arctic and subsequent downstream propagation to the North Atlantic of buoyancy anomalies controlled by temperature and salinity. Initially, during the first decade or so, the Arctic sea ice loss results in anomalous positive heat and salinity fluxes in the subpolar North Atlantic, inducing positive temperature and salinity anomalies over the regions of oceanic deep convection. At first, these anomalies largely compensate one another, leading to a minimal change in upper ocean density and deep convection in the North Atlantic. Over the following years, however, more anomalous warm water accumulates in the Arctic and spreads to the North Atlantic. At the same time, freshwater that accumulates from seasonal sea ice melting over most of the upper Arctic Ocean also spreads southward, reaching as far as south of Iceland. These warm and fresh anomalies reduce upper ocean density and suppress oceanic deep convection. The thermal and haline contributions to these buoyancy anomalies, and therefore to theAMOCslowdown during this period, are found to have similar magnitudes. We also find that the related changes in horizontal winddriven circulation could potentially push freshwater away from the deep convection areas and hence strengthen the AMOC, but this effect is overwhelmed by mean advection. Article in Journal/Newspaper Arctic Arctic Arctic Ocean Iceland North Atlantic Sea ice University of Southampton: e-Prints Soton Arctic Arctic Ocean Journal of Climate 32 4 977 996 |
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Open Polar |
collection |
University of Southampton: e-Prints Soton |
op_collection_id |
ftsouthampton |
language |
English |
description |
We explore the mechanisms by which Arctic sea ice decline affects the Atlantic meridional overturning circulation (AMOC) in a suite of numerical experiments perturbing the Arctic sea ice radiative budget within a fully coupled climate model. The imposed perturbations act to increase the amount of heat available to melt ice, leading to a rapid Arctic sea ice retreat within 5 years after the perturbations are activated. In response, the AMOC gradually weakens over the next ;100 years. The AMOC changes can be explained by the accumulation in the Arctic and subsequent downstream propagation to the North Atlantic of buoyancy anomalies controlled by temperature and salinity. Initially, during the first decade or so, the Arctic sea ice loss results in anomalous positive heat and salinity fluxes in the subpolar North Atlantic, inducing positive temperature and salinity anomalies over the regions of oceanic deep convection. At first, these anomalies largely compensate one another, leading to a minimal change in upper ocean density and deep convection in the North Atlantic. Over the following years, however, more anomalous warm water accumulates in the Arctic and spreads to the North Atlantic. At the same time, freshwater that accumulates from seasonal sea ice melting over most of the upper Arctic Ocean also spreads southward, reaching as far as south of Iceland. These warm and fresh anomalies reduce upper ocean density and suppress oceanic deep convection. The thermal and haline contributions to these buoyancy anomalies, and therefore to theAMOCslowdown during this period, are found to have similar magnitudes. We also find that the related changes in horizontal winddriven circulation could potentially push freshwater away from the deep convection areas and hence strengthen the AMOC, but this effect is overwhelmed by mean advection. |
format |
Article in Journal/Newspaper |
author |
Liu, Wei Fedorov, Alexey Sévellec, Florian |
spellingShingle |
Liu, Wei Fedorov, Alexey Sévellec, Florian The mechanisms of the Atlantic meridional overturning circulation slowdown induced by Arctic sea ice decline |
author_facet |
Liu, Wei Fedorov, Alexey Sévellec, Florian |
author_sort |
Liu, Wei |
title |
The mechanisms of the Atlantic meridional overturning circulation slowdown induced by Arctic sea ice decline |
title_short |
The mechanisms of the Atlantic meridional overturning circulation slowdown induced by Arctic sea ice decline |
title_full |
The mechanisms of the Atlantic meridional overturning circulation slowdown induced by Arctic sea ice decline |
title_fullStr |
The mechanisms of the Atlantic meridional overturning circulation slowdown induced by Arctic sea ice decline |
title_full_unstemmed |
The mechanisms of the Atlantic meridional overturning circulation slowdown induced by Arctic sea ice decline |
title_sort |
mechanisms of the atlantic meridional overturning circulation slowdown induced by arctic sea ice decline |
publishDate |
2019 |
url |
https://eprints.soton.ac.uk/430591/ |
geographic |
Arctic Arctic Ocean |
geographic_facet |
Arctic Arctic Ocean |
genre |
Arctic Arctic Arctic Ocean Iceland North Atlantic Sea ice |
genre_facet |
Arctic Arctic Arctic Ocean Iceland North Atlantic Sea ice |
op_relation |
Liu, Wei, Fedorov, Alexey and Sévellec, Florian (2019) The mechanisms of the Atlantic meridional overturning circulation slowdown induced by Arctic sea ice decline. Journal of Climate, 32 (4), 977-996. (doi:10.1175/JCLI-D-18-0231.1 <http://dx.doi.org/10.1175/JCLI-D-18-0231.1>). |
op_doi |
https://doi.org/10.1175/JCLI-D-18-0231.1 |
container_title |
Journal of Climate |
container_volume |
32 |
container_issue |
4 |
container_start_page |
977 |
op_container_end_page |
996 |
_version_ |
1772810571236769792 |