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| Titel |
A flood episode in northern Italy: multi-model and single-model mesoscale meteorological ensembles for hydrological predictions |
| VerfasserIn |
S. Davolio, M. M. Miglietta, T. Diomede, C. Marsigli, A. Montani |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1027-5606
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| Digitales Dokument |
URL |
| Erschienen |
In: Hydrology and Earth System Sciences ; 17, no. 6 ; Nr. 17, no. 6 (2013-06-05), S.2107-2120 |
| Datensatznummer |
250018892
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| Publikation (Nr.) |
 copernicus.org/hess-17-2107-2013.pdf |
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| Zusammenfassung |
Numerical weather prediction models can be coupled with hydrological models
to generate streamflow forecasts. Several ensemble approaches have been
recently developed in order to take into account the different sources of
errors and provide probabilistic forecasts feeding a flood forecasting
system. Within this framework, the present study aims at comparing two
high-resolution limited-area meteorological ensembles, covering short and
medium range, obtained via different methodologies, but implemented with
similar number of members, horizontal resolution (about 7 km), and driving
global ensemble prediction system. The former is a multi-model ensemble,
based on three mesoscale models (BOLAM, COSMO, and WRF), while the latter,
following a single-model approach, is the operational ensemble forecasting
system developed within the COSMO consortium, COSMO-LEPS (limited-area
ensemble prediction system).
The meteorological models are coupled with a distributed rainfall-runoff
model (TOPKAPI) to simulate the discharge of the Reno River (northern
Italy), for a recent severe weather episode affecting northern Apennines.
The evaluation of the ensemble systems is performed both from a
meteorological perspective over northern Italy and in terms of
discharge prediction over the Reno River basin during two periods of heavy
precipitation between 29 November and 2 December 2008. For each period,
ensemble performance has been compared at two different forecast ranges.
It is found that, for the intercomparison undertaken in this specific study,
both mesoscale model ensembles outperform the global ensemble for
application at basin scale. Horizontal resolution is found to play a
relevant role in modulating the precipitation distribution. Moreover, the
multi-model ensemble provides a better indication concerning the occurrence,
intensity and timing of the two observed discharge peaks, with respect to
COSMO-LEPS. This seems to be ascribable to the different behaviour of the
involved meteorological models.
Finally, a different behaviour comes out at different forecast ranges. For
short ranges, the impact of boundary conditions is weaker and the spread can
be mainly attributed to the different characteristics of the models. At
longer forecast ranges, the similar behaviour of the multi-model members
forced by the same large-scale conditions indicates that the systems are
governed mainly by the boundary conditions, although the different limited area
models' characteristics may still have a non-negligible impact. |
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