Latitudinal Migrations of the Subtropical Front at the Agulhas Plateau Through the Mid-Pleistocene Transition
The meridional variability of the Subtropical Front (STF) in the Southern Hemisphere, linked to expansions or contractions of the Southern Ocean, may have played an important role in global ocean circulation by moderating the magnitude of water exchange at the Indian-Atlantic Ocean Gateway, so calle...
Published in: | Paleoceanography and Paleoclimatology |
---|---|
Main Authors: | , , , , , , , , |
Format: | Text |
Language: | unknown |
Published: |
DigitalCommons@URI
2021
|
Subjects: | |
Online Access: | https://digitalcommons.uri.edu/gsofacpubs/2198 https://doi.org/10.1029/2020PA004084 |
id |
ftunivrhodeislan:oai:digitalcommons.uri.edu:gsofacpubs-3167 |
---|---|
record_format |
openpolar |
spelling |
ftunivrhodeislan:oai:digitalcommons.uri.edu:gsofacpubs-3167 2024-02-11T10:08:49+01:00 Latitudinal Migrations of the Subtropical Front at the Agulhas Plateau Through the Mid-Pleistocene Transition Cartagena-Sierra, Alejandra Berke, Melissa A. Robinson, Rebecca S. Marcks, Basia Castañeda, Isla S. Starr, Aidan Hall, Ian R. Hemming, Sidney R. LeVay, Leah J. 2021-07-01T07:00:00Z https://digitalcommons.uri.edu/gsofacpubs/2198 https://doi.org/10.1029/2020PA004084 unknown DigitalCommons@URI https://digitalcommons.uri.edu/gsofacpubs/2198 doi:10.1029/2020PA004084 https://doi.org/10.1029/2020PA004084 Graduate School of Oceanography Faculty Publications Agulhas plateau mid-pleistocene transition primary productivity sea surface temperature southern ocean fronts subtropical front text 2021 ftunivrhodeislan https://doi.org/10.1029/2020PA004084 2024-01-15T19:10:03Z The meridional variability of the Subtropical Front (STF) in the Southern Hemisphere, linked to expansions or contractions of the Southern Ocean, may have played an important role in global ocean circulation by moderating the magnitude of water exchange at the Indian-Atlantic Ocean Gateway, so called Agulhas Leakage. Here we present new biomarker records of upper water column temperature ((Formula presented.) and (Formula presented.)) and primary productivity (chlorins and alkenones) from marine sediments at IODP Site U1475 on the Agulhas Plateau, near the STF and within the Agulhas retroflection pathway. We use these multiproxy time-series records from 1.4 to 0.3 Ma to examine implied changes in the upper oceanographic conditions at the mid-Pleistocene transition (MPT, ca. 1.2–0.8 Ma). Our reconstructions, combined with prior evidence of migrations of the STF over the last 350 ka, suggest that in the Southwestern Indian Ocean the STF may have been further south from the Agulhas Plateau during the mid-Pleistocene Interim State (MPIS, MIS 23–12) and reached its northernmost position during MIS 34–24 and MIS 10. Comparison to a Globorotalia menardii-derived Agulhas Leakage reconstruction from the Cape Basin suggests that only the most extreme northward migrations of the STF are associated with reduced Agulhas Leakage. During the MPIS, STF migrations do not appear to control Agulhas Leakage variability, we suggest previously modeled shifting westerly winds may be responsible for the patterns observed. A detachment between STF migrations and Agulhas Leakage, in addition to invoking shifting westerly winds may also help explain changes in CO2 ventilation seen during the MPIS. Text Southern Ocean University of Rhode Island: DigitalCommons@URI Southern Ocean Indian Paleoceanography and Paleoclimatology 36 7 |
institution |
Open Polar |
collection |
University of Rhode Island: DigitalCommons@URI |
op_collection_id |
ftunivrhodeislan |
language |
unknown |
topic |
Agulhas plateau mid-pleistocene transition primary productivity sea surface temperature southern ocean fronts subtropical front |
spellingShingle |
Agulhas plateau mid-pleistocene transition primary productivity sea surface temperature southern ocean fronts subtropical front Cartagena-Sierra, Alejandra Berke, Melissa A. Robinson, Rebecca S. Marcks, Basia Castañeda, Isla S. Starr, Aidan Hall, Ian R. Hemming, Sidney R. LeVay, Leah J. Latitudinal Migrations of the Subtropical Front at the Agulhas Plateau Through the Mid-Pleistocene Transition |
topic_facet |
Agulhas plateau mid-pleistocene transition primary productivity sea surface temperature southern ocean fronts subtropical front |
description |
The meridional variability of the Subtropical Front (STF) in the Southern Hemisphere, linked to expansions or contractions of the Southern Ocean, may have played an important role in global ocean circulation by moderating the magnitude of water exchange at the Indian-Atlantic Ocean Gateway, so called Agulhas Leakage. Here we present new biomarker records of upper water column temperature ((Formula presented.) and (Formula presented.)) and primary productivity (chlorins and alkenones) from marine sediments at IODP Site U1475 on the Agulhas Plateau, near the STF and within the Agulhas retroflection pathway. We use these multiproxy time-series records from 1.4 to 0.3 Ma to examine implied changes in the upper oceanographic conditions at the mid-Pleistocene transition (MPT, ca. 1.2–0.8 Ma). Our reconstructions, combined with prior evidence of migrations of the STF over the last 350 ka, suggest that in the Southwestern Indian Ocean the STF may have been further south from the Agulhas Plateau during the mid-Pleistocene Interim State (MPIS, MIS 23–12) and reached its northernmost position during MIS 34–24 and MIS 10. Comparison to a Globorotalia menardii-derived Agulhas Leakage reconstruction from the Cape Basin suggests that only the most extreme northward migrations of the STF are associated with reduced Agulhas Leakage. During the MPIS, STF migrations do not appear to control Agulhas Leakage variability, we suggest previously modeled shifting westerly winds may be responsible for the patterns observed. A detachment between STF migrations and Agulhas Leakage, in addition to invoking shifting westerly winds may also help explain changes in CO2 ventilation seen during the MPIS. |
format |
Text |
author |
Cartagena-Sierra, Alejandra Berke, Melissa A. Robinson, Rebecca S. Marcks, Basia Castañeda, Isla S. Starr, Aidan Hall, Ian R. Hemming, Sidney R. LeVay, Leah J. |
author_facet |
Cartagena-Sierra, Alejandra Berke, Melissa A. Robinson, Rebecca S. Marcks, Basia Castañeda, Isla S. Starr, Aidan Hall, Ian R. Hemming, Sidney R. LeVay, Leah J. |
author_sort |
Cartagena-Sierra, Alejandra |
title |
Latitudinal Migrations of the Subtropical Front at the Agulhas Plateau Through the Mid-Pleistocene Transition |
title_short |
Latitudinal Migrations of the Subtropical Front at the Agulhas Plateau Through the Mid-Pleistocene Transition |
title_full |
Latitudinal Migrations of the Subtropical Front at the Agulhas Plateau Through the Mid-Pleistocene Transition |
title_fullStr |
Latitudinal Migrations of the Subtropical Front at the Agulhas Plateau Through the Mid-Pleistocene Transition |
title_full_unstemmed |
Latitudinal Migrations of the Subtropical Front at the Agulhas Plateau Through the Mid-Pleistocene Transition |
title_sort |
latitudinal migrations of the subtropical front at the agulhas plateau through the mid-pleistocene transition |
publisher |
DigitalCommons@URI |
publishDate |
2021 |
url |
https://digitalcommons.uri.edu/gsofacpubs/2198 https://doi.org/10.1029/2020PA004084 |
geographic |
Southern Ocean Indian |
geographic_facet |
Southern Ocean Indian |
genre |
Southern Ocean |
genre_facet |
Southern Ocean |
op_source |
Graduate School of Oceanography Faculty Publications |
op_relation |
https://digitalcommons.uri.edu/gsofacpubs/2198 doi:10.1029/2020PA004084 https://doi.org/10.1029/2020PA004084 |
op_doi |
https://doi.org/10.1029/2020PA004084 |
container_title |
Paleoceanography and Paleoclimatology |
container_volume |
36 |
container_issue |
7 |
_version_ |
1790608433517428736 |