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| Titel |
Anticyclonic atmospheric circulation as an analogue for the warm and dry mid-Holocene summer climate in central Scandinavia |
| VerfasserIn |
K. Antonsson, D. Chen, H. Seppä |
| 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 ; 4, no. 4 ; Nr. 4, no. 4 (2008-10-21), S.215-224 |
| Datensatznummer |
250001864
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| Publikation (Nr.) |
 copernicus.org/cp-4-215-2008.pdf |
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| Zusammenfassung |
| Climate reconstructions from central Scandinavia suggest that annual and
summer temperatures were rising during the early Holocene and reached their
maximum after 8000 cal yr BP. The period with highest temperatures was
characterized by increasingly low lake-levels and dry climate, with driest
and warmest conditions at about 7000 to 5000 cal yr BP. We compare the
reconstructed climate pattern with simulations of a climate model for the
last 9000 years and show that the model, which is predominantly driven by
solar insolation patterns, suggests less prominent mid-Holocene dry and warm
period in Scandinavia than the reconstructions. As an additional explanation
for the reconstructed climate, we argue that the trend from the moist early
Holocene towards dry and warm mid-Holocene was caused by a changing
atmospheric circulation pattern with a mid-Holocene dominance of summer-time
anticyclonic circulation. An extreme case of the anticyclonic conditions is
the persistent blocking high, an atmospheric pressure pattern that at
present often causes long spells of particularly dry and warm summer
weather, or "Indian summers". The argument is tested with daily
instrumental temperature and precipitation records in central Sweden and an
objective circulation classification based on surface air pressure over the
period 1900–2002. We conclude that the differences between the
precipitation and temperature climates under anticyclonic and
non-anticyclonic conditions are significant. Further, warm and dry
combination, as indicated by mid-Holocene reconstructions, is a typical
pattern under anticyclonic conditions. These results indicate that the
presented hypothesis for the mid-Holocene climate is likely valid. |
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