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| Titel |
Copula-based assimilation of radar and gauge information to derive bias-corrected precipitation fields |
| VerfasserIn |
S. Vogl, P. Laux, W. Qiu, G. Mao, H. Kunstmann |
| 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 ; 16, no. 7 ; Nr. 16, no. 7 (2012-07-25), S.2311-2328 |
| Datensatznummer |
250013381
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| Publikation (Nr.) |
 copernicus.org/hess-16-2311-2012.pdf |
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| Zusammenfassung |
This study addresses the problem of combining radar information and gauge
measurements. Gauge measurements are the best available source of absolute
rainfall intensity albeit their spatial availability is limited.
Precipitation information obtained by radar mimics well the spatial patterns
but is biased for their absolute values.
In this study copula models are used to describe the dependence structure
between gauge observations and rainfall derived from radar reflectivity at
the corresponding grid cells. After appropriate time series transformation to
generate "iid" variates, only the positive pairs (radar >0,
gauge >0) of the residuals are considered. As not each grid cell
can be assigned to one gauge, the integration of point information, i.e.
gauge rainfall intensities, is achieved by considering the structure and the
strength of dependence between the radar pixels and all the gauges within the
radar image. Two different approaches, namely Maximum Theta and
Multiple Theta, are presented. They finally allow for generating
precipitation fields that mimic the spatial patterns of the radar fields and
correct them for biases in their absolute rainfall intensities. The
performance of the approach, which can be seen as a bias-correction for radar
fields, is demonstrated for the Bavarian Alps. The bias-corrected rainfall
fields are compared to a field of interpolated gauge values (ordinary
kriging) and are validated with available gauge measurements. The simulated
precipitation fields are compared to an operationally corrected radar
precipitation field (RADOLAN). The copula-based approach performs similarly
well as indicated by different validation measures and successfully corrects
for errors in the radar precipitation. |
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