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| Titel |
Higher harmonic tweek sferics observed at low latitude: estimation of VLF reflection heights and tweek propagation distance |
| VerfasserIn |
S. Kumar, A. Kishore, V. Ramachandran |
| 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 ; 26, no. 6 ; Nr. 26, no. 6 (2008-06-11), S.1451-1459 |
| Datensatznummer |
250016117
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| Publikation (Nr.) |
 copernicus.org/angeo-26-1451-2008.pdf |
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| Zusammenfassung |
| Lightning generated signals recorded at a low-latitude station, Suva
(18.2° S, 178.3° E) Fiji, in the South Pacific region, during
September 2003–July 2004, are used to study the propagation features and
the reflection heights of tweek atmospherics in the waveguide formed by the
Earth's surface and the lower ionosphere. Tweeks are observed only during
the local night and the maximum harmonic (n) recorded is six. The occurrence
of tweeks with higher n progressively decreases as n increases. The dispersed
part of tweeks decreases as n increases. The attenuation factor has been
calculated for tweeks with n=1–3. The ionospheric reflection heights
obtained assuming the transverse magnetic mode of propagation for tweek
signals vary from 83–92 km. A higher harmonic of the same tweek is reflected
from about 2.0 km higher than the lower harmonic. For 90% of tweeks,
propagation distances are estimated to be between 1000–5000 km. Tweeks
with lower n propagate longer distances than the tweeks with higher n. |
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