Antarctic sea ice control on the depth of North Atlantic deep water
Changes in deep-ocean circulation and stratification have been argued to contribute to climatic shifts between glacial and interglacial climates by affecting the atmospheric carbon dioxide concentrations. It has been recently proposed that such changes are associated with variations in Antarctic sea...
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ftmit:oai:dspace.mit.edu:1721.1/124619 2023-06-11T04:04:11+02:00 Antarctic sea ice control on the depth of North Atlantic deep water Nadeau, Louis-Philippe Ferrari, Raffaele Jansen, Malte F. Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences 2020-04-09T14:17:54Z application/pdf https://hdl.handle.net/1721.1/124619 en eng American Meteorological Society 10.1175/JCLI-D-18-0519.1 Journal of climate 1520-0442 0894-8755 https://hdl.handle.net/1721.1/124619 Nadeau, Louis-Philippe, Raffaele Ferrari, and Malte F. Jansen, "Antarctic sea ice control on the depth of North Atlantic deep water." Journal of climate 32, 9 (May 2019): p. 2537-51 doi 10.1175/JCLI-D-18-0519.1 ©2019 Author(s) Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. American Meteorological Society Article http://purl.org/eprint/type/JournalArticle 2020 ftmit https://doi.org/10.1175/JCLI-D-18-0519.1 2023-05-29T08:19:42Z Changes in deep-ocean circulation and stratification have been argued to contribute to climatic shifts between glacial and interglacial climates by affecting the atmospheric carbon dioxide concentrations. It has been recently proposed that such changes are associated with variations in Antarctic sea ice through two possible mechanisms: an increased latitudinal extent of Antarctic sea ice and an increased rate of Antarctic sea ice formation. Both mechanisms lead to an upward shift of the Atlantic meridional overturning circulation (AMOC) above depths where diapycnal mixing is strong (above 2000 m), thus decoupling the AMOC from the abyssal overturning circulation. Here, these two hypotheses are tested using a series of idealized two-basin ocean simulations. To investigate independently the effect of an increased latitudinal ice extent from the effect of an increased ice formation rate, sea ice is parameterized as a latitude strip over which the buoyancy flux is negative. The results suggest that both mechanisms can effectively decouple the two cells of the meridional overturning circulation (MOC), and that their effects are additive. To illustrate the role of Antarctic sea ice in decoupling the AMOC and the abyssal overturning cell, the age of deep-water masses is estimated. An increase in both the sea ice extent and its formation rate yields a dramatic "aging" of deep-water masses if the sea ice is thick and acts as a lid, suppressing air-sea fluxes. The key role of vertical mixing is highlighted by comparing results using different profiles of vertical diffusivity. The implications of an increase in water mass ages for storing carbon in the deep ocean are discussed. ©2019 NSF (award no. OCE-1536515) NSF (award no. OCE-1736109) Article in Journal/Newspaper Antarc* Antarctic North Atlantic Deep Water North Atlantic Sea ice DSpace@MIT (Massachusetts Institute of Technology) Antarctic Journal of Climate 32 9 2537 2551 |
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English |
description |
Changes in deep-ocean circulation and stratification have been argued to contribute to climatic shifts between glacial and interglacial climates by affecting the atmospheric carbon dioxide concentrations. It has been recently proposed that such changes are associated with variations in Antarctic sea ice through two possible mechanisms: an increased latitudinal extent of Antarctic sea ice and an increased rate of Antarctic sea ice formation. Both mechanisms lead to an upward shift of the Atlantic meridional overturning circulation (AMOC) above depths where diapycnal mixing is strong (above 2000 m), thus decoupling the AMOC from the abyssal overturning circulation. Here, these two hypotheses are tested using a series of idealized two-basin ocean simulations. To investigate independently the effect of an increased latitudinal ice extent from the effect of an increased ice formation rate, sea ice is parameterized as a latitude strip over which the buoyancy flux is negative. The results suggest that both mechanisms can effectively decouple the two cells of the meridional overturning circulation (MOC), and that their effects are additive. To illustrate the role of Antarctic sea ice in decoupling the AMOC and the abyssal overturning cell, the age of deep-water masses is estimated. An increase in both the sea ice extent and its formation rate yields a dramatic "aging" of deep-water masses if the sea ice is thick and acts as a lid, suppressing air-sea fluxes. The key role of vertical mixing is highlighted by comparing results using different profiles of vertical diffusivity. The implications of an increase in water mass ages for storing carbon in the deep ocean are discussed. ©2019 NSF (award no. OCE-1536515) NSF (award no. OCE-1736109) |
author2 |
Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences |
format |
Article in Journal/Newspaper |
author |
Nadeau, Louis-Philippe Ferrari, Raffaele Jansen, Malte F. |
spellingShingle |
Nadeau, Louis-Philippe Ferrari, Raffaele Jansen, Malte F. Antarctic sea ice control on the depth of North Atlantic deep water |
author_facet |
Nadeau, Louis-Philippe Ferrari, Raffaele Jansen, Malte F. |
author_sort |
Nadeau, Louis-Philippe |
title |
Antarctic sea ice control on the depth of North Atlantic deep water |
title_short |
Antarctic sea ice control on the depth of North Atlantic deep water |
title_full |
Antarctic sea ice control on the depth of North Atlantic deep water |
title_fullStr |
Antarctic sea ice control on the depth of North Atlantic deep water |
title_full_unstemmed |
Antarctic sea ice control on the depth of North Atlantic deep water |
title_sort |
antarctic sea ice control on the depth of north atlantic deep water |
publisher |
American Meteorological Society |
publishDate |
2020 |
url |
https://hdl.handle.net/1721.1/124619 |
geographic |
Antarctic |
geographic_facet |
Antarctic |
genre |
Antarc* Antarctic North Atlantic Deep Water North Atlantic Sea ice |
genre_facet |
Antarc* Antarctic North Atlantic Deep Water North Atlantic Sea ice |
op_source |
American Meteorological Society |
op_relation |
10.1175/JCLI-D-18-0519.1 Journal of climate 1520-0442 0894-8755 https://hdl.handle.net/1721.1/124619 Nadeau, Louis-Philippe, Raffaele Ferrari, and Malte F. Jansen, "Antarctic sea ice control on the depth of North Atlantic deep water." Journal of climate 32, 9 (May 2019): p. 2537-51 doi 10.1175/JCLI-D-18-0519.1 ©2019 Author(s) |
op_rights |
Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. |
op_doi |
https://doi.org/10.1175/JCLI-D-18-0519.1 |
container_title |
Journal of Climate |
container_volume |
32 |
container_issue |
9 |
container_start_page |
2537 |
op_container_end_page |
2551 |
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1768385992193998848 |