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| Titel |
Verification of precipitation from the NWP nowcasting system at the DMI for a wet summer period |
| VerfasserIn |
Bjarke Tobias Olsen, Ulrik Smith Korsholm, Claus Petersen, Niels Woetmann Nielsen, Henrik Vedel, Bent Hansen Sass |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250098299
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| Publikation (Nr.) |
 EGU/EGU2014-13966.pdf |
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| Zusammenfassung |
| At the Danish Meteorological Institute the operational nowcasting modeling system utilizes a
newly introduced nudging-based radar-assimilation technique (Korsholm et al., 2014) in the
NWP model. In this method radar-derived rain-rates are used to estimate a vertical profile of
horizontal divergence that the horizontal divergence in the model is nudged towards.
Verification of precipitation forecasts by the nowcasting system using this technique is
presented for 17 days of august 2010 and compared to a reference where the radar nudging is
excluded. In Denmark this period in 2010 was particularly wet with several heavy
precipitation events with observed precipitation above 36 mm of rain during one hour. Three
of these events are studied in some detail. The verification is based on fractional skill
scores which give scale-selective scores of the spatial skill of the forecasts based on
radar-derived precipitation fields. The study shows that for precipitation values
above the 95th percentile the nudging technique have a strong impact on the spatial
skill of the forecast in the first 1-2 hours, and a smaller but still clear impact on
the 3-4 hour forecast length where skill percists in the forecast on scales down to
tens of kilometers. It is clear that the spatial smoothing of the model reduce the
forecast quality, and some indications of positive bias in precipitation intensities are
observed. |
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