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| Titel |
Extreme climate, not extreme weather: the summer of 1816 in Geneva, Switzerland |
| VerfasserIn |
R. Auchmann, S. Brönnimann, L. Breda, M. Bühler, R. Spadin, A. Stickler |
| 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 ; 8, no. 1 ; Nr. 8, no. 1 (2012-02-24), S.325-335 |
| Datensatznummer |
250005376
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| Publikation (Nr.) |
 copernicus.org/cp-8-325-2012.pdf |
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| Zusammenfassung |
| We analyze weather and climate during the "Year without Summer" 1816 using
sub-daily data from Geneva, Switzerland, representing one of the
climatically most severely affected regions. The record includes twice daily
measurements and observations of air temperature, pressure, cloud cover,
wind speed, and wind direction as well as daily measurements of
precipitation. Comparing 1816 to a contemporary reference period (1799–1821)
reveals that the coldness of the summer of 1816 was most prominent in the
afternoon, with a shift of the entire distribution function of temperature
anomalies by 3–4 °C. Early morning temperature anomalies show a smaller
change for the mean, a significant decrease in the variability, and no
changes in negative extremes. Analyzing cloudy and cloud-free conditions
separately suggests that an increase in the number of cloudy days was to a
significant extent responsible for these features. A daily weather type
classification based on pressure, pressure tendency, and wind direction
shows extremely anomalous frequencies in summer 1816, with only one day
(compared to 20 in an average summer) classified as high-pressure situation
but a tripling of low-pressure situations. The afternoon temperature
anomalies expected from only a change in weather types was much stronger
negative in summer 1816 than in any other year. For precipitation, our
analysis shows that the 80% increase in summer precipitation compared to
the reference period can be explained by 80% increase in the frequency of
precipitation, while no change could be found neither in the average
intensity of precipitation nor in the frequency distribution of extreme
precipitation. In all, the analysis shows that the regional circulation and
local cloud cover played a dominant role. It also shows that the summer of
1816 was an example of extreme climate, not extreme weather. |
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