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Higher harmonic tweek sferics observed at low latitude: estimation of VLF reflection heights and tweeks propagation distance

Kumar, Sushil and Kishore, Amol N. and Ramachandran, Visagaperuman (2008) Higher harmonic tweek sferics observed at low latitude: estimation of VLF reflection heights and tweeks propagation distance. Annales Geophysicae, 26 . pp. 1451-1459. ISSN 0992-7689

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Abstract

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 magneticmode 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.

Item Type: Journal Article
Subjects: Q Science > Q Science (General)
Q Science > QC Physics
Divisions: Faculty of Science, Technology and Environment (FSTE) > School of Engineering and Physics
Depositing User: Ms Neha Harakh
Date Deposited: 11 Jan 2008 12:21
Last Modified: 11 Jul 2012 17:41
URI: http://repository.usp.ac.fj/id/eprint/191
UNSPECIFIED

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