Centennial-scale variability of the Southern Hemisphere westerly wind belt in the eastern Pacific over the past two millennia
We present the first high-resolution (sub-annual) dust particle data set from West Antarctica, developed from the West Antarctic Ice Sheet (WAIS) Divide deep ice core (79.468° S, 112.086° W), and use it to reconstruct changes in atmospheric circulation over the past 2400 years. We find a background...
| Main Authors: | , , , , , , , |
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2014-06-01
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| Series: | Climate of the Past |
| Online Access: | http://www.clim-past.net/10/1125/2014/cp-10-1125-2014.pdf |
| _version_ | 1818974337616576512 |
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| author | B. G. Koffman K. J. Kreutz D. J. Breton E. J. Kane D. A. Winski S. D. Birkel A. V. Kurbatov M. J. Handley |
| author_facet | B. G. Koffman K. J. Kreutz D. J. Breton E. J. Kane D. A. Winski S. D. Birkel A. V. Kurbatov M. J. Handley |
| author_sort | B. G. Koffman |
| collection | DOAJ |
| description | We present the first high-resolution (sub-annual) dust particle data set from
West Antarctica, developed from the West Antarctic Ice Sheet (WAIS) Divide
deep ice core (79.468° S, 112.086° W), and use it to
reconstruct changes in atmospheric circulation over the past 2400 years. We
find a background dust flux of ~4 mg m<sup>−2</sup> year<sup>−1</sup> and a
mode particle size of 5–8 μm diameter. Through comparing the WAIS
Divide record with other Antarctic ice core particle records, we observe that
coastal and lower-elevation sites have higher dust fluxes and coarser
particle size distributions (PSDs) than sites on the East Antarctic plateau,
suggesting input from local dust sources at these lower-elevation sites. In
order to explore the use of the WAIS Divide dust PSD as a proxy for past
atmospheric circulation, we make quantitative comparisons between both
mid-latitude zonal wind speed and West Antarctic meridional wind speed and
the dust size record, finding significant positive interannual relationships.
We find that the dust PSD is related to mid-latitude zonal wind speed via
cyclonic activity in the Amundsen Sea region. Using our PSD record, and
through comparison with spatially distributed climate reconstructions from
the Southern Hemisphere (SH) middle and high latitudes, we infer that the SH
westerlies occupied a more southerly position from circa 1050 to 1400 CE
(Common Era), coinciding with the Medieval Climate Anomaly (MCA).
Subsequently, at ca. 1430 CE, the wind belt shifted equatorward, where it
remained until the mid-to-late twentieth century. We find covariability
between reconstructions of El Niño–Southern Oscillation (ENSO) and the
mid-latitude westerly winds in the eastern Pacific, suggesting that
centennial-scale circulation changes in this region are strongly influenced
by the tropical Pacific. Further, we observe increased coarse particle
deposition over the past 50 years, consistent with observations that the SH
westerlies have been shifting southward and intensifying in recent decades. |
| first_indexed | 2024-12-20T15:38:27Z |
| format | Article |
| id | doaj.art-111e9ed2a2bc46d5b042123c1f9d703b |
| institution | Directory Open Access Journal |
| issn | 1814-9324 1814-9332 |
| language | English |
| last_indexed | 2024-12-20T15:38:27Z |
| publishDate | 2014-06-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Climate of the Past |
| spelling | doaj.art-111e9ed2a2bc46d5b042123c1f9d703b2022-12-21T19:35:18ZengCopernicus PublicationsClimate of the Past1814-93241814-93322014-06-011031125114410.5194/cp-10-1125-2014Centennial-scale variability of the Southern Hemisphere westerly wind belt in the eastern Pacific over the past two millenniaB. G. Koffman0K. J. Kreutz1D. J. Breton2E. J. Kane3D. A. Winski4S. D. Birkel5A. V. Kurbatov6M. J. Handley7School of Earth and Climate Sciences, University of Maine, 5790 Bryand Global Sciences Center, Orono, ME 04469, USASchool of Earth and Climate Sciences, University of Maine, 5790 Bryand Global Sciences Center, Orono, ME 04469, USAClimate Change Institute, University of Maine, 300 Bryand Global Sciences Center, Orono, ME 04469, USASchool of Earth and Climate Sciences, University of Maine, 5790 Bryand Global Sciences Center, Orono, ME 04469, USASchool of Earth and Climate Sciences, University of Maine, 5790 Bryand Global Sciences Center, Orono, ME 04469, USAClimate Change Institute, University of Maine, 300 Bryand Global Sciences Center, Orono, ME 04469, USASchool of Earth and Climate Sciences, University of Maine, 5790 Bryand Global Sciences Center, Orono, ME 04469, USAClimate Change Institute, University of Maine, 300 Bryand Global Sciences Center, Orono, ME 04469, USAWe present the first high-resolution (sub-annual) dust particle data set from West Antarctica, developed from the West Antarctic Ice Sheet (WAIS) Divide deep ice core (79.468° S, 112.086° W), and use it to reconstruct changes in atmospheric circulation over the past 2400 years. We find a background dust flux of ~4 mg m<sup>−2</sup> year<sup>−1</sup> and a mode particle size of 5–8 μm diameter. Through comparing the WAIS Divide record with other Antarctic ice core particle records, we observe that coastal and lower-elevation sites have higher dust fluxes and coarser particle size distributions (PSDs) than sites on the East Antarctic plateau, suggesting input from local dust sources at these lower-elevation sites. In order to explore the use of the WAIS Divide dust PSD as a proxy for past atmospheric circulation, we make quantitative comparisons between both mid-latitude zonal wind speed and West Antarctic meridional wind speed and the dust size record, finding significant positive interannual relationships. We find that the dust PSD is related to mid-latitude zonal wind speed via cyclonic activity in the Amundsen Sea region. Using our PSD record, and through comparison with spatially distributed climate reconstructions from the Southern Hemisphere (SH) middle and high latitudes, we infer that the SH westerlies occupied a more southerly position from circa 1050 to 1400 CE (Common Era), coinciding with the Medieval Climate Anomaly (MCA). Subsequently, at ca. 1430 CE, the wind belt shifted equatorward, where it remained until the mid-to-late twentieth century. We find covariability between reconstructions of El Niño–Southern Oscillation (ENSO) and the mid-latitude westerly winds in the eastern Pacific, suggesting that centennial-scale circulation changes in this region are strongly influenced by the tropical Pacific. Further, we observe increased coarse particle deposition over the past 50 years, consistent with observations that the SH westerlies have been shifting southward and intensifying in recent decades.http://www.clim-past.net/10/1125/2014/cp-10-1125-2014.pdf |
| spellingShingle | B. G. Koffman K. J. Kreutz D. J. Breton E. J. Kane D. A. Winski S. D. Birkel A. V. Kurbatov M. J. Handley Centennial-scale variability of the Southern Hemisphere westerly wind belt in the eastern Pacific over the past two millennia Climate of the Past |
| title | Centennial-scale variability of the Southern Hemisphere westerly wind belt in the eastern Pacific over the past two millennia |
| title_full | Centennial-scale variability of the Southern Hemisphere westerly wind belt in the eastern Pacific over the past two millennia |
| title_fullStr | Centennial-scale variability of the Southern Hemisphere westerly wind belt in the eastern Pacific over the past two millennia |
| title_full_unstemmed | Centennial-scale variability of the Southern Hemisphere westerly wind belt in the eastern Pacific over the past two millennia |
| title_short | Centennial-scale variability of the Southern Hemisphere westerly wind belt in the eastern Pacific over the past two millennia |
| title_sort | centennial scale variability of the southern hemisphere westerly wind belt in the eastern pacific over the past two millennia |
| url | http://www.clim-past.net/10/1125/2014/cp-10-1125-2014.pdf |
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