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| Titel |
Centennial-scale variability of the Southern Hemisphere westerly wind belt in the eastern Pacific over the past two millennia |
| VerfasserIn |
B. G. Koffman, K. J. Kreutz, D. J. Breton, E. J. Kane, D. A. Winski, S. D. Birkel, A. V. Kurbatov, M. J. Handley |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1814-9324
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| Digitales Dokument |
URL |
| Erschienen |
In: Climate of the Past ; 10, no. 3 ; Nr. 10, no. 3 (2014-06-11), S.1125-1144 |
| Datensatznummer |
250116982
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| Publikation (Nr.) |
 copernicus.org/cp-10-1125-2014.pdf |
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| Zusammenfassung |
| 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−2 year−1 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. |
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