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| Titel |
Long-term variability of the thunderstorm and hail potential in Europe |
| VerfasserIn |
Susanna Mohr, Michael Kunz, Johannes Speidel, David Piper |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250126966
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| Publikation (Nr.) |
 EGU/EGU2016-6765.pdf |
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| Zusammenfassung |
| Severe thunderstorms and associated hazardous weather events such as hail frequently
cause considerable damage to buildings, crops, and automobiles, resulting in large
monetary costs in many parts of Europe and the world. To relate single extreme
hail events to the historic context and to estimate their return periods and possible
trends related to climate change, long-term statistics of hail events are required.
Due to the local-scale nature of hail and a lack of suitable observation systems,
however, hailstorms are not captured reliably and comprehensively for a long period of
time. In view of this fact, different proxies (indirect climate data) obtained from
sounding stations and regional climate models can be used to infer the probability and
intensity of thunderstorms or hailstorms. In contrast to direct observational data, such
proxies are available homogeneously over a long time period. The aim of the study is
to investigate the potential for severe thunderstorms and their changes over past
decades.
Statistical analyses of sounding data show that the convective potential over the past 20 –
30 years has significantly increased over large parts of Central Europe, making severe
thunderstorms more likely. A similar picture results from analyses of weather types that are
most likely associated with damaging hailstorms. These weather patterns have increased,
even if only slightly but nevertheless statistically significantly, in the time period from 1971
to 2000.
To improve the diagnostics of hail events in regional climate models, a logistic hail model
has been developed by means of a multivariate analysis method. The model is based on a
combination of appropriate hail-relevant meteorological parameters. The output of the
model is a new index that estimates the potential of the atmosphere for hailstorm
development, referred to as potential hail index (PHI). Applied to a high-resolved
reanalysis run for Europe driven by NCEP/NCAR1, long-term changes of the PHI for
60 years (1951–2010) show large annual and multiannual variability. The trends
are mostly positive in the western parts and negative to the east. However, due
to the large temporal variability, the trends are not significant at most of the grid
points. Furthermore, it becomes clear that the environmental conditions that favor the
formation of hailstorms prevail in larger areas. This finding suggests that, despite the
local-scale nature of convective storms, the ambient conditions favoring these events are
mainly controlled by large-scale circulation patterns and mechanisms. This result is
important to estimate the convective potential of the atmosphere in case of single
events. |
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