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Reconstructing atmospheric circulation over southern New Zealand: Establishment of modern westerly airflow 5500 years ago and implications for Southern Hemisphere Holocene climate change

Reconstructing atmospheric circulation over southern New Zealand: Establishment of modern westerly airflow 5500 years ago and implications for Southern Hemisphere Holocene climate change
Reconstructing atmospheric circulation over southern New Zealand: Establishment of modern westerly airflow 5500 years ago and implications for Southern Hemisphere Holocene climate change
Late-twentieth century changes in the intensity and migration of Southern Hemisphere westerly winds have been implicated in spatially complex variability in atmospheric and ocean circulation, and ice-sheet dynamics, across the mid- to high-latitudes. A major uncertainty, however, is whether present day hemispheric-wide symmetrical airflow is representative of past behaviour. Here we report a multi-proxy study from Stewart Island and southern Fiordland, New Zealand (46–47°S) reconstructing Holocene changes at the northern limit of westerly airflow. Increased minerogenic input and a pronounced shift in cool-loving vegetation around 5500 years ago is consistent with the establishment of westerly airflow at this latitude in the southwest Pacific. In marked contrast, stronger winds are reported further south over the subantarctic Auckland (50°S) and Campbell (52°S) Islands from 8000 years ago. Intriguingly, reconstructions from the east Pacific suggest a weakening of core westerly airflow after 8500 years ago, but an expansion along the northern limits sometime after 5500 years ago. Our results suggest similar atmospheric circulation changes have been experienced in the Pacific since 5500 years ago, but indicate an expanded network of sites is needed to comprehensively test the driver(s) and impact(s) of Holocene mid-latitude westerly winds across the Southern Hemisphere.
Jet stream, Roaring Forties, Southern Annular Mode (SAM), Southern Hemisphere westerly winds, Southern Ocean, Wind-blown sediments
0277-3791
77-87
Turney, C. S.M.
5e673fdb-42c9-4bc3-994a-519db28fdec8
Wilmshurst, J. M.
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Jones, R. T.
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Wood, J. R.
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Palmer, J. G.
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Hogg, A. G.
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Fenwick, P.
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Crowley, S. F.
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Privat, K.
aef475fd-9ea1-4000-95a3-90bf09940b0c
Thomas, Z.
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et al.
Turney, C. S.M.
5e673fdb-42c9-4bc3-994a-519db28fdec8
Wilmshurst, J. M.
3738ab11-0f7b-4550-b8d3-f63198b3394e
Jones, R. T.
f8b5db51-10c7-4b4e-81e3-e5c3833eb2ce
Wood, J. R.
b983087b-d812-4f6a-9e67-ad7039a6b5b2
Palmer, J. G.
6b327a39-f234-4cdc-ae73-0c48340f05b3
Hogg, A. G.
11978083-6632-42e2-ac46-4e0f9cd709c9
Fenwick, P.
8ce718a6-f147-4eac-9878-f8b67c491a70
Crowley, S. F.
cbfdb9e1-4454-4fc4-b53f-91ac1734545a
Privat, K.
aef475fd-9ea1-4000-95a3-90bf09940b0c
Thomas, Z.
4b512d3a-3478-4270-9fdd-61256aa640d3

Turney, C. S.M., Wilmshurst, J. M., Jones, R. T. and Thomas, Z. , et al. (2017) Reconstructing atmospheric circulation over southern New Zealand: Establishment of modern westerly airflow 5500 years ago and implications for Southern Hemisphere Holocene climate change. Quaternary Science Reviews, 159 (3), 77-87. (doi:10.1016/j.quascirev.2016.12.017).

Record type: Article

Abstract

Late-twentieth century changes in the intensity and migration of Southern Hemisphere westerly winds have been implicated in spatially complex variability in atmospheric and ocean circulation, and ice-sheet dynamics, across the mid- to high-latitudes. A major uncertainty, however, is whether present day hemispheric-wide symmetrical airflow is representative of past behaviour. Here we report a multi-proxy study from Stewart Island and southern Fiordland, New Zealand (46–47°S) reconstructing Holocene changes at the northern limit of westerly airflow. Increased minerogenic input and a pronounced shift in cool-loving vegetation around 5500 years ago is consistent with the establishment of westerly airflow at this latitude in the southwest Pacific. In marked contrast, stronger winds are reported further south over the subantarctic Auckland (50°S) and Campbell (52°S) Islands from 8000 years ago. Intriguingly, reconstructions from the east Pacific suggest a weakening of core westerly airflow after 8500 years ago, but an expansion along the northern limits sometime after 5500 years ago. Our results suggest similar atmospheric circulation changes have been experienced in the Pacific since 5500 years ago, but indicate an expanded network of sites is needed to comprehensively test the driver(s) and impact(s) of Holocene mid-latitude westerly winds across the Southern Hemisphere.

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More information

Accepted/In Press date: 15 December 2016
Published date: 1 March 2017
Additional Information: Publisher Copyright: © 2016 Elsevier Ltd
Keywords: Jet stream, Roaring Forties, Southern Annular Mode (SAM), Southern Hemisphere westerly winds, Southern Ocean, Wind-blown sediments

Identifiers

Local EPrints ID: 476049
URI: http://eprints.soton.ac.uk/id/eprint/476049
ISSN: 0277-3791
PURE UUID: 749e9249-d531-468d-bc52-bf7f223aa01f
ORCID for Z. Thomas: ORCID iD orcid.org/0000-0002-2323-4366

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Date deposited: 04 Apr 2023 17:01
Last modified: 17 Mar 2024 04:18

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Contributors

Author: C. S.M. Turney
Author: J. M. Wilmshurst
Author: R. T. Jones
Author: J. R. Wood
Author: J. G. Palmer
Author: A. G. Hogg
Author: P. Fenwick
Author: S. F. Crowley
Author: K. Privat
Author: Z. Thomas ORCID iD
Corporate Author: et al.

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