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Titel |
Improving the rainfall rate estimation in the midstream of the Heihe River Basin using raindrop size distribution |
VerfasserIn |
G. Zhao, R. Chu, T. Zhang, J. Li, J. Shen, Z. Wu |
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 ; 15, no. 3 ; Nr. 15, no. 3 (2011-03-16), S.943-951 |
Datensatznummer |
250012691
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Publikation (Nr.) |
copernicus.org/hess-15-943-2011.pdf |
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Zusammenfassung |
During the intensive observation period of the Watershed Allied Telemetry
Experimental Research (WATER), a total of 1074 raindrop size distribution
were measured by the Parsivel disdrometer, the latest state-of-the-art optical
laser instrument. Because of the limited observation data in Qinghai-Tibet
Plateau, the modelling behaviour was not well done. We used raindrop size
distributions to improve the rain rate estimator of meteorological radar in
order to obtain many accurate rain rate data in this area. We got the
relationship between the terminal velocity of the raindrop and the diameter (mm) of a raindrop: v(D) = 4.67D0.53. Then four types of estimators for
X-band polarimetric radar are examined. The simulation results show that the
classical estimator R (ZH) is most sensitive to variations in DSD and the
estimator R (KDP, ZH, ZDR) is the best estimator for estimating
the rain rate. An X-band polarimetric radar (714XDP) is used for verifying
these estimators. The lowest sensitivity of the rain rate estimator R (KDP, ZH, ZDR) to variations in DSD can be explained by the following facts. The difference in the forward-scattering amplitudes at
horizontal and vertical polarizations, which contributes KDP, is
proportional to the 3rd power of the drop diameter. On the other hand,
the exponent of the backscatter cross-section, which contributes to
ZH, is proportional to the 6th power of the drop diameter. Because
the rain rate R is proportional to the 3.57th power of the drop
diameter, KDP is less sensitive to DSD variations than ZH. |
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