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| Titel |
On the statistical relationship between cloud optical and microphysical characteristics and rainfall intensity for convective storms over the Mediterranean |
| VerfasserIn |
E. Cattani, F. Torricella, S. Laviola, V. Levizzani |
| 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 ; 9, no. 6 ; Nr. 9, no. 6 (2009-12-23), S.2135-2142 |
| Datensatznummer |
250007078
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| Publikation (Nr.) |
 copernicus.org/nhess-9-2135-2009.pdf |
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| Zusammenfassung |
The relationship between the multi-spectral cloud field characterization from
the Advanced Very High Resolution Radiometer (AVHRR) and the rainfall
intensities from the Advanced Microwave Sounding Unit-module B (AMSU-B) data
were studied for a convective storm event, which occurred during the first
15 days of June 2007 over the Mediterranean. The cloud products exploited in
this analysis, cloud mask, type, optical thickness, and effective radius, are
obtained from the NOAA-NESDIS operational processing system Clouds from the
AVHRR-Extended algorithm (CLAVR-x), whereas the rain intensity values are
retrieved from the AMSU-B brightness temperatures via a fast algorithm, using
opaque frequencies (centred at 183 GHz) to correct for the presence of water
vapour affecting the retrieval results. The algorithm is conceived to
discriminate between convective and stratiform rain using a suitable set of
thresholds; the retrieval is subsequently carried out separately for the two
types.
A test for the discrimination of precipitating from non-precipitating areas
was based on the comparison between the precipitation information and the
retrieved cloud parameters. The test produced a cloud optical thickness
threshold value, beyond which the precipitation initiates, and an effective
radius range for the identification of the precipitating clouds. The results
stemming from the application of the test to the June 2007 case study are
very encouraging, although still preliminary and restricted to the analyzed
Mediterranean storms. In particular, the test shows high potential for
delineating non-precipitating areas (more than 90% of successful cases for
every considered cloud type) and to identify precipitating ice clouds
related to convective rain (confirmed by 82% of hits). On the other
hand, the relative inability to address the stratiform cloud systems is
proved by the fact that the majority of the missed cases, for each cloud
types, is characterized by light rain intensities (≤3 mm h−1). |
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