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| Titel |
Linking atmospheric blocking to European temperature extremes in spring |
| VerfasserIn |
Lukas Brunner, Gabriele Hegerl, Andrea Steiner |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250150172
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| Publikation (Nr.) |
 EGU/EGU2017-14603.pdf |
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| Zusammenfassung |
| The weather in Europe is influenced by a range of dynamical features such as the
Atlantic storm tracks, the jet stream, and atmospheric blocking. Blocking describes an
atmospheric situation in which a stationary and persistent high pressure system
interrupts the climatological flow for several days to weeks. It can trigger cold
and warm spells which is of special relevance during the spring season because
vegetation is particularly vulnerable to extreme temperatures in the early greening
phase.
We investigate European cold and warm spells in the 36 springs from 1979 to 2014 in
temperature data from the European daily high-resolution gridded dataset (E-OBS) and
connect them to blocking derived from geopotential height fields from ERA-Interim. A
highly significant link between blocking and both, cold and warm spells is found that changes
during spring. Resolving monthly frequencies, we find a shift in the preferred locations of
blocking throughout spring. The maximum blocking frequency during cold spells shifts from
Scandinavia to the British Isles in March and April. During warm spells it continuously shifts
further northward during the spring season.
The location of the block is found to be essential for the sign of the relationship.
Blocking over the north-eastern Atlantic and over northern Europe is strongly linked
to cold conditions, while blocking over central Europe is associated with warm
conditions. Consistently the spatial distribution of temperature extremes across
Europe is highly sensitive to the occurrence of blocking. More than 80 % of cold
spells in south-eastern Europe occur during blocking, compared to less than 30 % in
northern Europe. Warm spells show the opposite pattern and more than 70 % co-occur
with blocking in northern Europe, compared to less than 30 % in parts of southern
Europe.
We find considerable interannual variability over the analysis period from 1979 to 2014 but
also a decrease in cold spells and an increase in warm spells, especially in the last 15 years,
indicating the influence of global warming. The change to a warmer environment holds the
potential for even higher vulnerability to cold extremes, which can be triggered by blocking
in late spring.
Brunner, L., G. Hegerl, and A. Steiner, 2017: Connecting Atmospheric Blocking to European
Temperature Extremes in Spring. J. Climate, 30, 585–594, doi: 10.1175/JCLI-D-16-0518.1. |
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