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| Titel |
Dealing with uncertainty: an analysis of the severe weather events over Italy in 2006 |
| VerfasserIn |
L. Molini, A. Parodi, F. Siccardi |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1561-8633
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| Digitales Dokument |
URL |
| Erschienen |
In: Natural Hazards and Earth System Science ; 9, no. 6 ; Nr. 9, no. 6 (2009-11-05), S.1775-1786 |
| Datensatznummer |
250007048
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| Publikation (Nr.) |
 copernicus.org/nhess-9-1775-2009.pdf |
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| Zusammenfassung |
Forecast verification is a long-standing issue of the whole meteorologists'
community. A common definition of a truly satisfying prediction skill has not
been achieved so far. Even the definition of "event", due to its
spatio-temporal discontinuity, is highly affected by uncertainty.
Moreover, decision-making demands numerical weather prediction modellers to
provide information about the "inner" uncertainty, i.e. the degree of
uncertainty related to the choice of a specific setting of the model
(microphysics, turbulence scheme, convective closure, etc.).
Most European Mediterranean countries, due to dense development, steep
coastal orography and short hydrological response time of the drainage
basins, have to deal very frequently with flash floods and sudden shallow
land sliding impacting on urban areas. Civil protection organizations are in
place to issue early warnings in order to allow local authorities and
population to take precautionary measures. To do so in Mediterranean
catchments, hydrologists are required to use numerical rainfall predictions
in place of rainfall observations on large European catchments.
Estimating the measure of uncertainty is for this reason crucial.
The goal of this work is to propose an objective evaluation of the
performance of the currently operational weather prediction model COSMO-I7
over quite a long time period and to check forecast verification at different
space-time scales by the comparison of predictions with observations.
Due to large investments in the last years, in fact, Italy has built up one
of the most dense hourly-reporting network of rain gauges. The network has a
mean space density of about 1/100 km2, very similar to the horizontal
resolution of currently operating limited area models.
An objective procedure to identify and compare the extreme events of
precipitation has been applied to the full set of rainfall observations and
over the severe events forecast by COSMO-I7 and announced in official
warnings by Italian Civil Protection Department.
The procedure allows to classify rainfall events as long-lived and spatially
distributed or as having a shorter duration and a minor spatial extent. We
show that long-lived events are less affected by overall uncertainty than
short-lived ones, yet the inner uncertainty of the event affects both. |
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