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| Titel |
Enhanced radar precipitation estimates using a combined clutter and beam blockage correction technique |
| VerfasserIn |
A. Fornasiero, J. Bech, P. P. Alberoni |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1561-8633
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| Digitales Dokument |
URL |
| Erschienen |
In: Natural Hazards and Earth System Science ; 6, no. 5 ; Nr. 6, no. 5 (2006-07-27), S.697-710 |
| Datensatznummer |
250003704
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| Publikation (Nr.) |
 copernicus.org/nhess-6-697-2006.pdf |
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| Zusammenfassung |
| Weather radar observations are currently the most reliable method for remote
sensing of precipitation. However, a number of factors affect the quality of
radar observations and may limit seriously automated quantitative
applications of radar precipitation estimates such as those required in
Numerical Weather Prediction (NWP) data assimilation or in hydrological
models. In this paper, a technique to correct two different problems
typically present in radar data is presented and evaluated. The aspects
dealt with are non-precipitating echoes – caused either by permanent ground
clutter or by anomalous propagation of the radar beam (anaprop echoes) – and
also topographical beam blockage. The correction technique is based in the
computation of realistic beam propagation trajectories based upon recent
radiosonde observations instead of
assuming standard radio propagation conditions. The correction consists of
three different steps: 1) calculation of a Dynamic Elevation Map which
provides the minimum clutter-free antenna elevation for each pixel within
the radar coverage; 2) correction for residual anaprop, checking the
vertical reflectivity gradients within the radar volume; and 3)
topographical beam blockage estimation and correction using a geometric
optics approach. The technique is evaluated with four case studies in the
region of the Po Valley (N Italy) using a C-band Doppler radar and a network
of raingauges providing hourly precipitation measurements. The case studies
cover different seasons, different radio propagation conditions and also
stratiform and convective precipitation type events. After applying the
proposed correction, a comparison of the radar precipitation estimates with
raingauges indicates a general reduction in both the root mean squared error
and the fractional error variance indicating the efficiency and robustness
of the procedure. Moreover, the technique presented is not computationally
expensive so it seems well suited to be implemented in an operational
environment. |
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