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| Titel |
Holocene climate variability in the winter rainfall zone of South Africa |
| VerfasserIn |
S. Weldeab, J.-B. W. Stuut, R. R. Schneider, W. Siebel |
| 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 ; 9, no. 5 ; Nr. 9, no. 5 (2013-10-22), S.2347-2364 |
| Datensatznummer |
250085234
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| Publikation (Nr.) |
 copernicus.org/cp-9-2347-2013.pdf |
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| Zusammenfassung |
| We established a multi-proxy time series comprising analyses of major
elements in bulk sediments, Sr and Nd isotopes, grain size of terrigenous
fraction, and δ18O and δ13C in tests of
Neogloboquadrina pachyderma (sinistral) from a marine sediment sequence recovered off the Orange River.
The records reveal coherent patterns of variability that reflect changes in
wind strength, precipitation over the river catchments, and upwelling of
cold and nutrient-rich coastal waters off western South Africa. The wettest
episode of the Holocene in the winter rainfall zone (WRZ) of South Africa
occurred during the "Little Ice Age" (700–100 cal years BP) most
likely in response to a northward shift of the austral westerlies. Wet phases
and strengthened coastal water upwellings are companied by a decrease of
Agulhas water leakage into the South Atlantic and a reduced dust
incursion over Antarctica, as indicated in previous studies. A continuous
aridification trend in the WRZ and a weakening of the southern Benguela
Upwelling System (BUS) between 9000 and 5500 cal years BP parallel with
increase of dust deposition over Antarctica and an enhanced leakage of warm
Agulhas water into the eastern South Atlantic. The temporal relationship
between precipitation changes in the WRZ, the thermal state of the coastal
surface water, and leakage of warm water in the South Atlantic, and variation
of dust incursion over Antarctica suggests a causal link that most likely
was related to latitudinal shifts of the Southern Hemisphere westerlies. Our
results of the mid-Holocene time interval may serve as an analogue to a
possible long-term consequence of the current and future southward shift of
the westerlies. Furthermore, warming of the coastal surface water as a
result of warm Agulhas water incursion into the southern BUS may affect
coastal fog formation. |
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