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| Titel |
Impact of high-resolution data assimilation of GPS zenith delay on Mediterranean heavy rainfall forecasting |
| VerfasserIn |
K. Boniface, V. Ducrocq, G. Jaubert, X. Yan, P. Brousseau, F. Masson, C. Champollion, J. Chéry, E. Doerflinger |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
0992-7689
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| Digitales Dokument |
URL |
| Erschienen |
In: Annales Geophysicae ; 27, no. 7 ; Nr. 27, no. 7 (2009-07-09), S.2739-2753 |
| Datensatznummer |
250016585
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| Publikation (Nr.) |
 copernicus.org/angeo-27-2739-2009.pdf |
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| Zusammenfassung |
Impact of GPS (Global Positioning System) data assimilation is assessed here
using a high-resolution numerical weather prediction system at 2.5 km
horizontal resolution. The Zenithal Tropospheric Delay (ZTD) GPS data from
mesoscale networks are assimilated with the 3DVAR AROME data assimilation
scheme. Data from more than 280 stations over the model domain have been
assimilated during 15-day long assimilation cycles prior each of the two
studied events. The results of these assimilation cycles show that the
assimilation of GPS ZTD with the AROME system performs well in producing
analyses closer to the ZTD observations in average.
Then the impacts of assimilating GPS data on the precipitation forecast have
been evaluated. For the first case, only the AROME runs starting a few hours
prior the triggering of the convective system are able to simulate the
convective precipitation. The assimilation of GPS ZTD observations improves
the simulation of the spatial extent of the precipitation, but slightly
underestimates the heaviest precipitation in that case compared with the
experiment without GPS. The accuracy of the precipitation forecast for the
second case is much better. The analyses from the control assimilation cycle
provide already a good description of the atmosphere state that cannot be
further improved by the assimilation of GPS observations. Only for the latest
day (22 November 2007), significant differences have been found between the
two parallel cycles. In that case, the assimilation of GPS ZTD allows to
improve the first 6 to 12 h of the precipitation forecast. |
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