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| Titel |
Whistler intensities above thunderstorms |
| VerfasserIn |
J. Fiser, J. Chum, G. Diendorfer, M. Parrot, O. Santolík |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
0992-7689
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| Digitales Dokument |
URL |
| Erschienen |
In: Annales Geophysicae ; 28, no. 1 ; Nr. 28, no. 1 (2010-01-13), S.37-46 |
| Datensatznummer |
250016741
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| Publikation (Nr.) |
 copernicus.org/angeo-28-37-2010.pdf |
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| Zusammenfassung |
| We report a study of penetration of the VLF electromagnetic waves induced by
lightning to the ionosphere. We compare the fractional hop whistlers recorded
by the ICE experiment onboard the DEMETER satellite with lightning detected
by the EUCLID detection network. To identify the fractional hop whistlers, we
have developed software for automatic detection of the fractional-hop
whistlers in the VLF spectrograms. This software provides the detection times
of the fractional hop whistlers and the average amplitudes of these
whistlers. Matching the lightning and whistler data, we find the pairs of
causative lightning and corresponding whistler. Processing data from
~200 DEMETER passes over the European region we obtain a map of mean
amplitudes of whistler electric field as a function of latitudinal and
longitudinal difference between the location of the causative lightning and
satellite magnetic footprint. We find that mean whistler amplitude
monotonically decreases with horizontal distance up to ~1000 km from
the lightning source. At larger distances, the mean whistler amplitude
usually merges into the background noise and the whistlers become
undetectable. The maximum of whistler intensities is shifted from the
satellite magnetic footprint ~1° owing to the oblique
propagation. The average amplitude of whistlers increases with the lightning
current. At nighttime (late evening), the average amplitude of whistlers is
about three times higher than during the daytime (late morning) for the same
lightning current. |
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