Tracking Southern Ocean Sea Ice Extent With Winter Water: A New Method Based on the Oxygen Isotopic Signature of Foraminifera
Southern Ocean sea ice plays a central role in the oceanic meridional overturning circulation, transforming globally prevalent watermasses through surface buoyancy loss and gain. Buoyancy loss due to surface cooling and sea ice growth promotes the formation of bottom water that flows into the Atlant...
Published in: | Paleoceanography and Paleoclimatology |
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Main Authors: | , , , |
Format: | Article in Journal/Newspaper |
Language: | English |
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American Geophysical Union
2021
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Online Access: | https://authors.library.caltech.edu/109196/ https://authors.library.caltech.edu/109196/6/2020PA004095.pdf https://authors.library.caltech.edu/109196/1/2020PA004095.pdf https://authors.library.caltech.edu/109196/3/2020pa004095-sup-0001-supporting%20information%20si-s01.docx https://authors.library.caltech.edu/109196/5/2020pa004095-sup-0002-table%20si-s01.xlsx https://resolver.caltech.edu/CaltechAUTHORS:20210519-141321689 |
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ftcaltechauth:oai:authors.library.caltech.edu:109196 2023-05-15T18:16:09+02:00 Tracking Southern Ocean Sea Ice Extent With Winter Water: A New Method Based on the Oxygen Isotopic Signature of Foraminifera Lund, David C. Chase, Zanna Kohfeld, Karen E. Wilson, Earle A. 2021-06 application/pdf application/msword application/vnd.ms-excel https://authors.library.caltech.edu/109196/ https://authors.library.caltech.edu/109196/6/2020PA004095.pdf https://authors.library.caltech.edu/109196/1/2020PA004095.pdf https://authors.library.caltech.edu/109196/3/2020pa004095-sup-0001-supporting%20information%20si-s01.docx https://authors.library.caltech.edu/109196/5/2020pa004095-sup-0002-table%20si-s01.xlsx https://resolver.caltech.edu/CaltechAUTHORS:20210519-141321689 en eng American Geophysical Union https://authors.library.caltech.edu/109196/6/2020PA004095.pdf https://authors.library.caltech.edu/109196/1/2020PA004095.pdf https://authors.library.caltech.edu/109196/3/2020pa004095-sup-0001-supporting%20information%20si-s01.docx https://authors.library.caltech.edu/109196/5/2020pa004095-sup-0002-table%20si-s01.xlsx Lund, David C. and Chase, Zanna and Kohfeld, Karen E. and Wilson, Earle A. (2021) Tracking Southern Ocean Sea Ice Extent With Winter Water: A New Method Based on the Oxygen Isotopic Signature of Foraminifera. Paleoceanography and Paleoclimatology, 36 (6). Art. No. e2020PA004095. ISSN 2572-4517. doi:10.1029/2020pa004095. https://resolver.caltech.edu/CaltechAUTHORS:20210519-141321689 <https://resolver.caltech.edu/CaltechAUTHORS:20210519-141321689> other Article PeerReviewed 2021 ftcaltechauth https://doi.org/10.1029/2020pa004095 2021-12-02T18:39:15Z Southern Ocean sea ice plays a central role in the oceanic meridional overturning circulation, transforming globally prevalent watermasses through surface buoyancy loss and gain. Buoyancy loss due to surface cooling and sea ice growth promotes the formation of bottom water that flows into the Atlantic, Indian, and Pacific basins, while buoyancy gain due to sea ice melt helps transform the returning deep flow into intermediate and mode waters. Because northward expansion of Southern Ocean sea ice during the Last Glacial Maximum (LGM; 19–23 kyr BP) may have enhanced deep ocean stratification and contributed to lower atmospheric CO₂ levels, reconstructions of sea ice extent are critical to understanding the LGM climate state. Here, we present a new sea ice proxy based on the ¹⁸O/¹⁶O ratio of foraminifera (δ¹⁸O_c). In the seasonal sea ice zone, sea ice formation during austral winter creates a cold surface mixed layer that persists in the sub-surface during spring and summer. The cold sub-surface layer, known as winter water, sits above relatively warm deep water, creating an inverted temperature profile. The unique surface-to-deep temperature contrast is reflected in estimates of equilibrium δ¹⁸O_c, implying that paired analysis of planktonic and benthic foraminifera can be used to infer sea ice extent. To demonstrate the feasibility of the δ¹⁸O_c method, we present a compilation of N. pachyderma and Cibicidoides spp. results from the Atlantic sector that yields an estimate of winter sea ice extent consistent with modern observations. Article in Journal/Newspaper Sea ice Southern Ocean Caltech Authors (California Institute of Technology) Austral Indian Pacific Southern Ocean Paleoceanography and Paleoclimatology 36 6 |
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Open Polar |
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Caltech Authors (California Institute of Technology) |
op_collection_id |
ftcaltechauth |
language |
English |
description |
Southern Ocean sea ice plays a central role in the oceanic meridional overturning circulation, transforming globally prevalent watermasses through surface buoyancy loss and gain. Buoyancy loss due to surface cooling and sea ice growth promotes the formation of bottom water that flows into the Atlantic, Indian, and Pacific basins, while buoyancy gain due to sea ice melt helps transform the returning deep flow into intermediate and mode waters. Because northward expansion of Southern Ocean sea ice during the Last Glacial Maximum (LGM; 19–23 kyr BP) may have enhanced deep ocean stratification and contributed to lower atmospheric CO₂ levels, reconstructions of sea ice extent are critical to understanding the LGM climate state. Here, we present a new sea ice proxy based on the ¹⁸O/¹⁶O ratio of foraminifera (δ¹⁸O_c). In the seasonal sea ice zone, sea ice formation during austral winter creates a cold surface mixed layer that persists in the sub-surface during spring and summer. The cold sub-surface layer, known as winter water, sits above relatively warm deep water, creating an inverted temperature profile. The unique surface-to-deep temperature contrast is reflected in estimates of equilibrium δ¹⁸O_c, implying that paired analysis of planktonic and benthic foraminifera can be used to infer sea ice extent. To demonstrate the feasibility of the δ¹⁸O_c method, we present a compilation of N. pachyderma and Cibicidoides spp. results from the Atlantic sector that yields an estimate of winter sea ice extent consistent with modern observations. |
format |
Article in Journal/Newspaper |
author |
Lund, David C. Chase, Zanna Kohfeld, Karen E. Wilson, Earle A. |
spellingShingle |
Lund, David C. Chase, Zanna Kohfeld, Karen E. Wilson, Earle A. Tracking Southern Ocean Sea Ice Extent With Winter Water: A New Method Based on the Oxygen Isotopic Signature of Foraminifera |
author_facet |
Lund, David C. Chase, Zanna Kohfeld, Karen E. Wilson, Earle A. |
author_sort |
Lund, David C. |
title |
Tracking Southern Ocean Sea Ice Extent With Winter Water: A New Method Based on the Oxygen Isotopic Signature of Foraminifera |
title_short |
Tracking Southern Ocean Sea Ice Extent With Winter Water: A New Method Based on the Oxygen Isotopic Signature of Foraminifera |
title_full |
Tracking Southern Ocean Sea Ice Extent With Winter Water: A New Method Based on the Oxygen Isotopic Signature of Foraminifera |
title_fullStr |
Tracking Southern Ocean Sea Ice Extent With Winter Water: A New Method Based on the Oxygen Isotopic Signature of Foraminifera |
title_full_unstemmed |
Tracking Southern Ocean Sea Ice Extent With Winter Water: A New Method Based on the Oxygen Isotopic Signature of Foraminifera |
title_sort |
tracking southern ocean sea ice extent with winter water: a new method based on the oxygen isotopic signature of foraminifera |
publisher |
American Geophysical Union |
publishDate |
2021 |
url |
https://authors.library.caltech.edu/109196/ https://authors.library.caltech.edu/109196/6/2020PA004095.pdf https://authors.library.caltech.edu/109196/1/2020PA004095.pdf https://authors.library.caltech.edu/109196/3/2020pa004095-sup-0001-supporting%20information%20si-s01.docx https://authors.library.caltech.edu/109196/5/2020pa004095-sup-0002-table%20si-s01.xlsx https://resolver.caltech.edu/CaltechAUTHORS:20210519-141321689 |
geographic |
Austral Indian Pacific Southern Ocean |
geographic_facet |
Austral Indian Pacific Southern Ocean |
genre |
Sea ice Southern Ocean |
genre_facet |
Sea ice Southern Ocean |
op_relation |
https://authors.library.caltech.edu/109196/6/2020PA004095.pdf https://authors.library.caltech.edu/109196/1/2020PA004095.pdf https://authors.library.caltech.edu/109196/3/2020pa004095-sup-0001-supporting%20information%20si-s01.docx https://authors.library.caltech.edu/109196/5/2020pa004095-sup-0002-table%20si-s01.xlsx Lund, David C. and Chase, Zanna and Kohfeld, Karen E. and Wilson, Earle A. (2021) Tracking Southern Ocean Sea Ice Extent With Winter Water: A New Method Based on the Oxygen Isotopic Signature of Foraminifera. Paleoceanography and Paleoclimatology, 36 (6). Art. No. e2020PA004095. ISSN 2572-4517. doi:10.1029/2020pa004095. https://resolver.caltech.edu/CaltechAUTHORS:20210519-141321689 <https://resolver.caltech.edu/CaltechAUTHORS:20210519-141321689> |
op_rights |
other |
op_doi |
https://doi.org/10.1029/2020pa004095 |
container_title |
Paleoceanography and Paleoclimatology |
container_volume |
36 |
container_issue |
6 |
_version_ |
1766189600630374400 |