Evidence for increased expression of the Amundsen Sea Low over the South Atlantic during the late Holocene
Evidence for increased expression of the Amundsen Sea Low over the South Atlantic during the late Holocene
The Amundsen Sea Low (ASL) plays a major role in the climate and environment of Antarctica and the Southern Ocean, including surface air temperature and sea ice concentration changes. Unfortunately, a relative dearth of observational data across the Amundsen and Bellingshausen seas prior to the satellite era (post-1979) limits our understanding of the past behaviour and impact of the ASL. The limited proxy evidence for changes in the ASL are primarily restricted to the Antarctic where ice core evidence suggests a deepening of the atmospheric pressure system during the late Holocene. However, no data have previously been reported from the northern side of the ASL. Here we report a high-resolution, multi-proxy study of a 5000-year-long peat record from the Falkland Islands, a location sensitive to contemporary ASL dynamics which modulates northerly and westerly airflow across the southwestern South Atlantic sector of the Southern Ocean. In combination with climate reanalysis, we find a marked period of wetter, colder conditions most likely the result of enhanced southerly airflow between 5000 and 2500 years ago, suggesting limited ASL influence over the region. After 2500 years ago, drier and warmer conditions were established, implying more westerly airflow and the increased projection of the ASL onto the South Atlantic. The possible role of the equatorial Pacific via atmospheric teleconnections in driving this change is discussed. Our results are in agreement with Antarctic ice core records and fjord sediments from the southern South American coast, and suggest that the Falkland Islands provide a valuable location for reconstructing high southern latitude atmospheric circulation changes on multi-decadal to millennial timescales.
1727-1738
Thomas, Zoë A.
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Jones, Richard T.
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Fogwill, Chris J.
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Hatton, Jackie
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Williams, Alan N.
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Hogg, Alan
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Mooney, Scott
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Jones, Philip
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Lister, David
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Mayewski, Paul
367fe005-36a2-4185-bba7-0794e30905ab
Turney, Chris S.M.
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13 November 2018
Thomas, Zoë A.
4b512d3a-3478-4270-9fdd-61256aa640d3
Jones, Richard T.
f8b5db51-10c7-4b4e-81e3-e5c3833eb2ce
Fogwill, Chris J.
3bad6ae9-5a6d-467e-b523-9d5ed0147455
Hatton, Jackie
8b0781fb-6ee8-4cae-93f6-ee12cec8b0f6
Williams, Alan N.
1cb0b99a-5e2d-4f60-8c0f-7f672c48736d
Hogg, Alan
11978083-6632-42e2-ac46-4e0f9cd709c9
Mooney, Scott
3bbe1af4-84f6-4678-aba6-4f90dd1c8ba2
Jones, Philip
ff8ce557-fd3f-4500-8cee-10842cd223b2
Lister, David
8f77e3f0-f0f2-4631-a092-d08ea40b6012
Mayewski, Paul
367fe005-36a2-4185-bba7-0794e30905ab
Turney, Chris S.M.
5149b57c-77c2-4375-97a2-a4f00aa74d97
Thomas, Zoë A., Jones, Richard T., Fogwill, Chris J. and Jones, Philip
,
et al.
(2018)
Evidence for increased expression of the Amundsen Sea Low over the South Atlantic during the late Holocene.
Climate of the Past, 14 (11), .
(doi:10.5194/cp-14-1727-2018).
Abstract
The Amundsen Sea Low (ASL) plays a major role in the climate and environment of Antarctica and the Southern Ocean, including surface air temperature and sea ice concentration changes. Unfortunately, a relative dearth of observational data across the Amundsen and Bellingshausen seas prior to the satellite era (post-1979) limits our understanding of the past behaviour and impact of the ASL. The limited proxy evidence for changes in the ASL are primarily restricted to the Antarctic where ice core evidence suggests a deepening of the atmospheric pressure system during the late Holocene. However, no data have previously been reported from the northern side of the ASL. Here we report a high-resolution, multi-proxy study of a 5000-year-long peat record from the Falkland Islands, a location sensitive to contemporary ASL dynamics which modulates northerly and westerly airflow across the southwestern South Atlantic sector of the Southern Ocean. In combination with climate reanalysis, we find a marked period of wetter, colder conditions most likely the result of enhanced southerly airflow between 5000 and 2500 years ago, suggesting limited ASL influence over the region. After 2500 years ago, drier and warmer conditions were established, implying more westerly airflow and the increased projection of the ASL onto the South Atlantic. The possible role of the equatorial Pacific via atmospheric teleconnections in driving this change is discussed. Our results are in agreement with Antarctic ice core records and fjord sediments from the southern South American coast, and suggest that the Falkland Islands provide a valuable location for reconstructing high southern latitude atmospheric circulation changes on multi-decadal to millennial timescales.
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Accepted/In Press date: 8 October 2018
Published date: 13 November 2018
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Funding Information:
Acknowledgements. We would like to acknowledge the incredible debt we owe to our close friend and colleague Richard T. Jones without whom this work would not have been possible. We miss you Richard. This project was supported by the Australian Research Council (grant no. FL100100195 and DP130104156). We thank the Falkland Islands Government for permission to undertake sampling on the island (permit number R07/2011) and Darren Christie for assisting with the fieldwork. We thank two anonymous reviewers for their constructive comments on an earlier version of this manuscript.
Publisher Copyright:
© 2018 Author(s).
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Local EPrints ID: 476037
URI: http://eprints.soton.ac.uk/id/eprint/476037
ISSN: 1814-9324
PURE UUID: ec52a86d-b239-4219-81da-01fbd1b229f9
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Date deposited: 04 Apr 2023 16:56
Last modified: 18 Mar 2024 04:10
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Author:
Zoë A. Thomas
Author:
Richard T. Jones
Author:
Chris J. Fogwill
Author:
Jackie Hatton
Author:
Alan N. Williams
Author:
Alan Hogg
Author:
Scott Mooney
Author:
Philip Jones
Author:
David Lister
Author:
Paul Mayewski
Author:
Chris S.M. Turney
Corporate Author: et al.
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