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...
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2021
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ftunivtasmania:oai:eprints.utas.edu.au:46608 2023-05-15T13:43:28+02:00 Tracking Southern Ocean sea ice extent with winter water: a new method based on the oxygen isotopic signature of foraminifera Lund, DC Chase, Z Kohfeld, KE Wilson, EA 2021 application/pdf https://eprints.utas.edu.au/46608/ https://eprints.utas.edu.au/46608/1/150278%20-%20Tracking%20Southern%20Ocean%20sea%20ice%20extent%20with%20winter%20water.pdf en eng Wiley-Blackwell Publishing Inc. https://eprints.utas.edu.au/46608/1/150278%20-%20Tracking%20Southern%20Ocean%20sea%20ice%20extent%20with%20winter%20water.pdf Lund, DC, Chase, Z orcid:0000-0001-5060-779X , Kohfeld, KE and Wilson, EA 2021 , 'Tracking Southern Ocean sea ice extent with winter water: a new method based on the oxygen isotopic signature of foraminifera' , Paleoceanography and Paleoclimatology, vol. 36, no. 6 , pp. 1-17 , doi:10.1029/2020PA004095 <http://dx.doi.org/10.1029/2020PA004095>. sea ice Antarctic Southern Ocean proxy winter water Article PeerReviewed 2021 ftunivtasmania https://doi.org/10.1029/2020PA004095 2022-07-25T22:16:41Z 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 (δ18Oc). 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 δ18Oc, implying that paired analysis of planktonic and benthic foraminifera can be used to infer sea ice extent. To demonstrate the feasibility of the δ18Oc 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 Antarc* Antarctic Sea ice Southern Ocean University of Tasmania: UTas ePrints Antarctic Austral Indian Pacific Southern Ocean Paleoceanography and Paleoclimatology 36 6 |
institution |
Open Polar |
collection |
University of Tasmania: UTas ePrints |
op_collection_id |
ftunivtasmania |
language |
English |
topic |
sea ice Antarctic Southern Ocean proxy winter water |
spellingShingle |
sea ice Antarctic Southern Ocean proxy winter water Lund, DC Chase, Z Kohfeld, KE Wilson, EA Tracking Southern Ocean sea ice extent with winter water: a new method based on the oxygen isotopic signature of foraminifera |
topic_facet |
sea ice Antarctic Southern Ocean proxy winter water |
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 (δ18Oc). 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 δ18Oc, implying that paired analysis of planktonic and benthic foraminifera can be used to infer sea ice extent. To demonstrate the feasibility of the δ18Oc 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, DC Chase, Z Kohfeld, KE Wilson, EA |
author_facet |
Lund, DC Chase, Z Kohfeld, KE Wilson, EA |
author_sort |
Lund, DC |
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 |
Wiley-Blackwell Publishing Inc. |
publishDate |
2021 |
url |
https://eprints.utas.edu.au/46608/ https://eprints.utas.edu.au/46608/1/150278%20-%20Tracking%20Southern%20Ocean%20sea%20ice%20extent%20with%20winter%20water.pdf |
geographic |
Antarctic Austral Indian Pacific Southern Ocean |
geographic_facet |
Antarctic Austral Indian Pacific Southern Ocean |
genre |
Antarc* Antarctic Sea ice Southern Ocean |
genre_facet |
Antarc* Antarctic Sea ice Southern Ocean |
op_relation |
https://eprints.utas.edu.au/46608/1/150278%20-%20Tracking%20Southern%20Ocean%20sea%20ice%20extent%20with%20winter%20water.pdf Lund, DC, Chase, Z orcid:0000-0001-5060-779X , Kohfeld, KE and Wilson, EA 2021 , 'Tracking Southern Ocean sea ice extent with winter water: a new method based on the oxygen isotopic signature of foraminifera' , Paleoceanography and Paleoclimatology, vol. 36, no. 6 , pp. 1-17 , doi:10.1029/2020PA004095 <http://dx.doi.org/10.1029/2020PA004095>. |
op_doi |
https://doi.org/10.1029/2020PA004095 |
container_title |
Paleoceanography and Paleoclimatology |
container_volume |
36 |
container_issue |
6 |
_version_ |
1766189282751414272 |