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| Titel |
Lightning activity in the deep convective clouds with the overshooting tops |
| VerfasserIn |
Petra Mikuš, Natasa Strelec Mahović |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250073384
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| Zusammenfassung |
| In this study, spatial and temporal characteristics of lightning distribution and polarity as well
as portion of cloud to ground (CG) and intra cloud (IC) lightning in the convective clouds
with overshooting tops (OT) are analyzed. Analysis of lightning activity in the thunderstorms
with OT was done for the warm part of the year, from May to September during 2009 and
2010. The study area covers region from approximately 41°N 8°E to 49.5°N 24°E. Deep
convective clouds with OT were detected from the Meteosat 9 data, using a so called COMB
method based on the infrared window (IRW, 10.8 μm) channel and the absorption
channels of water vapor (WV, 6.2 μm) and ozone (O3, 9.7 μm) in form of brightness
temperature differences (BTD). COMB method combines the criteria for the IRW
brightness temperature and the criteria for two BTDs, WV-IRW and O3-IRW. All
pixels with O3-IRW BTD larger than 13 K in the region where IRW brightness
temperature is lower than 215 K and WV-IRW BTD larger than 4 K are characterized as
OTs.
Lightning data were provided by the Lightning Location System, which is part of the
International Lightning Detection Network in Europe (LINET). The LINET system detects
total lightning discharge, but it also separately detects cloud to ground (CG), or intra cloud
and cloud to cloud strokes (IC). For each satellite pixel meeting the OT, occurrence of
lightning discharge was searched 5 min before and after the time of the scan within the range
of 0.05° from the pixel position.
The results show that spatial distribution of lightning activity coincides well with the
spatial distribution of the detected OTs. The largest numbers of lightning strokes, as well
as OTs were detected in the western Hungary, southeastern Germany, northern
Adriatic and southern Adriatic coastal region at the slopes of the Dinaric Alps. In
general, the largest number of OTs occur between 14 and 21 UTC, while from 06 to
10 UTC OT detections are rather rare. Lightning activity shows similar temporal
distribution. Sharp increase in lightning activity and larger values of the electric current
are evident at the time of the OT detections. At those times, lightnings occur well
above the tropopause, being clearly related to the OT parts of the Cumulonimbus
cloud. |
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