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Titel |
The Soverato flood in Southern Italy: performance of global and limited-area ensemble forecasts |
VerfasserIn |
A. Montani, C. Marsigli, F. Nerozzi, T. Paccagnella, S. Tibaldi, R. Buizza |
Medientyp |
Artikel
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Sprache |
Englisch
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ISSN |
1023-5809
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Digitales Dokument |
URL |
Erschienen |
In: Nonlinear Processes in Geophysics ; 10, no. 3 ; Nr. 10, no. 3, S.261-274 |
Datensatznummer |
250007995
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Publikation (Nr.) |
copernicus.org/npg-10-261-2003.pdf |
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Zusammenfassung |
The predictability
of the flood event affecting Soverato (Southern Italy) in September 2000
is investigated by considering three different configurations of ECMWF
ensemble: the operational Ensemble Prediction System (EPS), the targeted
EPS and a high-resolution version of EPS. For each configuration, three
successive runs of ECMWF ensemble with the same verification time are
grouped together so as to generate a highly-populated
"super-ensemble". Then, five members are selected from the
super-ensemble and used to provide initial and boundary conditions for the
integrations with a limited-area model, whose runs generate a Limited-area
Ensemble Prediction System (LEPS). The relative impact of targeting the
initial perturbations against increasing the horizontal resolution is
assessed for the global ensembles as well as for the properties
transferred to LEPS integrations, the attention being focussed on the
probabilistic prediction of rainfall over a localised area. At the 108, 84
and 60- hour forecast ranges, the overall performance of the global
ensembles is not particularly accurate and the best results are obtained
by the high-resolution version of EPS. The LEPS performance is very
satisfactory in all configurations and the rainfall maps show probability
peaks in the correct regions. LEPS products would have been of great
assistance to issue flood risk alerts on the basis of limited-area
ensemble forecasts. For the 60-hour forecast range, the sensitivity of the
results to the LEPS ensemble size is discussed by comparing a 5-member
against a 51-member LEPS, where the limited-area model is nested on all
EPS members. Little sensitivity is found as concerns the detection of the
regions most likely affected by heavy precipitation, the probability peaks
being approximately the same in both configurations. |
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