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| Titel |
ELF-VLF atmospheric waveforms under night-time ionospheric conditions |
| VerfasserIn |
A. I. Sukhorukov |
| 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 ; 14, no. 1 ; Nr. 14, no. 1, S.33-41 |
| Datensatznummer |
250012135
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| Publikation (Nr.) |
 copernicus.org/angeo-14-33-1996.pdf |
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| Zusammenfassung |
| Tweek atmospherics generated by lightning
discharges and propagated in the night-time Earth-ionosphere waveguide, have
often very pronounced dispersive features near the first few waveguide cut-off
frequencies ( fcm~m\dot{s} fc1,
fc 1~1.6–1.9 kHz, m=1, 2, . . . , ),
being very extended in time, and have rather large amplitudes of oscillations
with periods corresponding to the narrow vicinity of the cut-off frequencies. In
this paper an analytical approach is developed to describe the waveform of
distant tweeks. It is based on the solving of the Maxwell equations in two
qualitatively different regions, whose changes are related in the first instance
to the changes in the relative magnitudes of the displacement current and
components of the conduction currents, and the following asymptotic matching of
the solutions in the transitional region. The analytical night-time waveguide
model accounts for both anisotropy and vertical inhomogeneity of the low
ionosphere. The model is valid for upper ELF – lower VLF range and is well
suitable for the analysis of the QTEm modes in the cut-off
frequency regions, which determine the most important part of the tweek spectra
and tweek amplitudes. The influence of the different ionospheric heights on the
tweek characteristics is determined. The efficiency of the tweek generation by
cloud-to-cloud discharge is also evaluated. |
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