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| Titel |
Radar subpixel-scale rainfall variability and uncertainty: lessons learned from observations of a dense rain-gauge network |
| VerfasserIn |
N. Peleg, M. Ben-Asher, E. Morin |
| 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 ; 17, no. 6 ; Nr. 17, no. 6 (2013-06-14), S.2195-2208 |
| Datensatznummer |
250018899
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| Publikation (Nr.) |
 copernicus.org/hess-17-2195-2013.pdf |
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| Zusammenfassung |
| Runoff and flash flood generation are very sensitive to rainfall's spatial
and temporal variability. The increasing use of radar and satellite data in
hydrological applications, due to the sparse distribution of rain gauges over
most catchments worldwide, requires furthering our knowledge of the
uncertainties of these data. In 2011, a new super-dense network of rain
gauges containing 14 stations, each with two side-by-side gauges, was
installed within a 4 km2 study area near Kibbutz Galed in northern
Israel. This network was established for a detailed exploration of the
uncertainties and errors regarding rainfall variability within a common pixel
size of data obtained from remote sensing systems for timescales of 1 min to
daily. In this paper, we present the analysis of the first year's record
collected from this network and from the Shacham weather radar, located
63 km from the study area. The gauge–rainfall spatial correlation and
uncertainty were examined along with the estimated radar error. The nugget
parameter of the inter-gauge rainfall correlations was high (0.92 on the
1 min scale) and increased as the timescale increased. The variance
reduction factor (VRF), representing the uncertainty from averaging a number
of rain stations per pixel, ranged from 1.6% for the 1 min timescale to
0.07% for the daily scale. It was also found that at least three rain
stations are needed to adequately represent the rainfall (VRF < 5%) on
a typical radar pixel scale. The difference between radar and rain gauge
rainfall was mainly attributed to radar estimation errors, while the gauge
sampling error contributed up to 20% to the total difference. The ratio of
radar rainfall to gauge-areal-averaged rainfall, expressed by the error
distribution scatter parameter, decreased from 5.27 dB for 3 min timescale
to 3.21 dB for the daily scale. The analysis of the radar errors and
uncertainties suggest that a temporal scale of at least 10 min should be
used for hydrological applications of the radar data. Rainfall measurements
collected with this dense rain gauge network will be used for further
examination of small-scale rainfall's spatial and temporal variability in the
coming years. |
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