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| Titel |
Polarimetric signatures indicative of severe storm development - the Pentecost event 2014 |
| VerfasserIn |
Silke Troemel, Malte Diederich, Raquel Evaristo, Alexander Ryzhkov, Clemens Simmer |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250105314
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| Publikation (Nr.) |
 EGU/EGU2015-4818.pdf |
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| Zusammenfassung |
| The 2014 Pentecost weekend storms in Europe were a series of severe supercell storms which
followed a heatwave in early June 2014, resulting from a Spanish plume synoptic weather
pattern. Outbreaks of severe weather were reported from these storm developments with the
worst damages occurring over the German state of North Rhine-Westphalia on 9 June, where
the storm was described as one of the most violent in decades by the German weather service
(DWD). During this event six fatalities, wind gusts up to 150km/h, hail and a flash
flood in Düsseldorf has been reported. Monitoring and analysis of high-impact
weather using weather radars of shorter wavelength (X- and C-bands) requires
special methods, i.e. anomalous high attenuation and differential attenuation due to
very large raindrops originating from melting large hail has to be investigated and
corrected. During the Pentecost event a record breaking ZDR bias of up to -25dB has
been observed. Different strategies for reliable attenuation correction and rainfall
estimation for this extreme event are explored and will be presented. A national 3D
composite of polarimetric moments covering Germany with 1km horizontal, 250m
vertical, and 5 minutes temporal resolution has been generated. 10 C-band radars from
the DWD radar network, recently upgraded to polarimetry, have been included.
Meanie3D, a 3D scale space tracking algorithm, is applied to the composite to
investigate the magnitudes and temporal development of the 3 fundamental steps of a
storms lifecycle: 1) high values of differential reflectivity ZDR aloft first indicate a
developing cell, 2) ZDR-columns (these are vertical columns of high differential
reflectivity) then indicate the updraft zone of a cell in the mature state. The vertical extent
of the ZDR-column is thus a measure of the strength of the updraft and for the
ensuing rainfall enhancement. 3) The very first big drops reach the surface before
the most intense rain begins. This is reflected by the polarimetric fingerprint for
differential sedimentation. While preliminary correlation analysis of moderate storms
hints at a lag-time between updraft strength and rainfall of 5-10 minutes, the case
study on hand suggest increasing lead time depending on the strength of the storm.
Magnitudes of ZDR enhancements associated with convective updrafts and differential
sedimentation and associated lead times for the Pentecost event will be presented. |
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