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Titel |
Long-term NAO reconstruction using lake sediments from W Greenland |
VerfasserIn |
Jesper Olsen, Mads Knudsen, John N. Anderson |
Konferenz |
EGU General Assembly 2013
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Medientyp |
Artikel
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Sprache |
Englisch
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Digitales Dokument |
PDF |
Erschienen |
In: GRA - Volume 15 (2013) |
Datensatznummer |
250083356
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Zusammenfassung |
Climate in the Arctic region and northwestern Europe is strongly affected by the North
Atlantic Oscillation, the dominant mode of atmospheric variability at mid-latitudes in the
North Atlantic region. The North Atlantic Oscillation index is an indicator for atmospheric
circulation patterns across the North Atlantic Ocean: when the index is positive, weather
conditions in Europe and the eastern US are mild and wet, whereas Greenland and northern
Canada are cold and dry. A negative index is associated with the reverse pattern.
Reconstructions of the North Atlantic Oscillation have been limited to the past 900 years.
Here we analyse a high-resolution lake sediment record of redox variability from
southwestern Greenland over the past 5,200 years to reconstruct lake thermal stratification,
and link the results to an existing reconstruction of the North Atlantic Oscillation index from
tree rings and speleothems. Using therelationship between the two records, we find that
around 4,500 and 650 years ago - at the end of the Holocene Thermal Maximum and
the beginning of the Little Ice Age, respectively - the North Atlantic Oscillation
changed from generally positive to variable, intermittently negative conditions. We
suggest that changes in the dominant state of the North Atlantic Oscillation tend to
coincide with significant climate transitions, but note that the onset of the Medieval
Climate anomaly around AD 950 did not coincide with any changes in the NAO. |
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