A comparative study of measured amplitude and phase perturbations of VLF and LF radio signals induced by solar flares
Very Low Frequency (VLF) and Low Frequency (LF) signal perturbations were examined to study ionospheric disturbances induced by solar X-ray flares in order to understand processes involved in propagation of VLF/LF radio signals over short paths and to estimate specific characteristics of each short...
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Veröffentlicht in: | Serbian astronomical journal. 2014, Vol.2014 (188), p.45-54 |
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Format: | Artikel |
Sprache: | eng |
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Zusammenfassung: | Very Low Frequency (VLF) and Low Frequency (LF) signal perturbations were
examined to study ionospheric disturbances induced by solar X-ray flares in
order to understand processes involved in propagation of VLF/LF radio signals
over short paths and to estimate specific characteristics of each short path.
The receiver at the Belgrade station is constantly monitoring the amplitude
and phase of a coherent and subionospherically propagating LF signal operated
in Sicily NSC at 45.90 kHz, and a VLF signal operated in Isola di Tavolara
ICV at 20.27 kHz, with the great circle distances of 953 km and 976 km,
respectively. A significant number of similarities between these short paths
is a direct result of both transmitters and the receiver?s geographic
location. The main difference is in transmitter frequencies. From July 2008
to February 2014 there were about 200 events that were chosen for further
examination. All selected examples showed that the amplitude and phase of VLF
and LF signals were perturbed by solar X-ray flares occurrence. This six-year
period covers both minimum and maximum of solar activity. Simultaneous
measurement of amplitude and phase of the VLF/LF signals during a solar flare
occurrence was applied to evaluate the electron density profile versus
altitude, to carry out the function of time over the middle Europe. |
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ISSN: | 1450-698X 1820-9289 |
DOI: | 10.2298/SAJ1488045S |