Effects of a Solar Eclipse on the Propagation of VLF-LF Signals: Observations and Results

De, B. K.; De, S. S.; Bandyopadhyay, Bidhan C.; Pal, Pinaki; Ali, Rousan; Paul, Suman; Goswami, Prabir Kanta

doi:10.3319/tao.2011.01.17.01(aa)

Cited by 14 publications

(8 citation statements)

References 35 publications

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“…Mullayarov et al [1999] also studied the VLF radio noise on frequency range 0.47–8.7 kHz during the solar eclipse on March 09, 1997 and reported 15–30% enhancement in amplitude with respect to the normal daily variation. De et al [2011] also reported an increase of amplitude in low frequency sferics at 81 kHz during the solar eclipse on 22nd July 2009. In the light of that, our present paper deals with the change in VLF sferics intensity at two consecutive solar eclipses at six discrete VLF frequencies which makes studies in this field more comprehensive.…”

Section: Discussionmentioning

confidence: 84%

Spectral character of VLF sferics propagating inside the Earth‐ionosphere waveguide during two recent solar eclipses

Guha

Choudhury

et al. 2012

J. Geophys. Res.

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Effects of solar eclipses on the propagation characteristics of worldwide VLF sferics from lightning activity require more investigation. An attempt was made on the occasion of two solar eclipses during 22nd July, 2009 and 15th January, 2010 to study the effects of the two eclipses on the propagation characteristics of VLF sferics in the Earth‐ionosphere waveguide. Identical experimental setups were used to study the VLF sferics during the two eclipse events. The spectral character of VLF sferics propagating inside the waveguide is studied at a fixed receiver location (23.75°N, 91.25°E) at six discrete frequencies in between 3 and 20 kHz. During both the eclipse events, it is observed that VLF sferics at all the six discrete frequencies is increased from the mean normal average ambient level. The increment peaks around 10–12 kHz with an overall increment of 6.4 dB with respect to its ambient level. The VLF spectral character of enhancement of sferics show similar characters in two eclipses. The percentage decrease in electron density using standard modeling equations is found to be 90% at the height of 71 km for both the eclipses, supporting linear variation of electron density with solar radiation at the D‐region of the ionosphere. The results are explained qualitatively on the basis of a decrease in electron density at the lower ionosphere modifying the reflection coefficient which affected the propagation of VLF sferics in Earth‐ionosphere waveguide during eclipsed condition.

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Section: Discussionmentioning

confidence: 84%

Spectral character of VLF sferics propagating inside the Earth‐ionosphere waveguide during two recent solar eclipses

Guha

Choudhury

et al. 2012

J. Geophys. Res.

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“… Guha et al [2010] showed a decrease (3.2 dB) in the amplitude of VLF transmitter signals (18.2 kHz) in India at the peak of the total solar eclipse of 22 July 2009. De et al [2011] also reported a decrease in the amplitude of VLF/LF transmitter signals from Australia (19.8 kHz) and Japan (40 kHz) to India during the same solar eclipse.…”

Section: Introductionmentioning

confidence: 79%

“…Several studies using VLF/LF/MF transmitter signals have also examined the lower ionosphere during solar eclipses [e.g., Bracewell , 1952; Crary and Schneible , 1965; Lynn , 1981; Abraham et al , 1998; Clilverd et al , 2001; Guha et al , 2010; De et al , 2011]. Bracewell [1952] first reported solar eclipse effects on VLF transmitter signals, sent from Rugby (16 kHz) to Cambridge in the UK.…”

Section: Introductionmentioning

confidence: 99%

Reflection height of daytime tweek atmospherics during the solar eclipse of 22 July 2009

Ohya¹,

Tsuchiya²,

Nakata³

et al. 2012

J. Geophys. Res.

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[1] We report multipoint observations of daytime tweek atmospherics during the solar eclipse of 22 July 2009. Sixteen and sixty-three tweek atmospherics were observed at Moshiri and Kagoshima, Japan, where the magnitudes of the solar eclipse were 0.458 and 0.966, respectively. This was the first observation of tweek atmospherics during a low-magnitude eclipse (0.458). The average and standard deviation of the reflection height were 94.9 AE 13.7 km at Moshiri and 87.2 AE 12.9 km at Kagoshima. The reflection height at Moshiri was almost the same as that for normal nighttime conditions in July (96.7 AE 12.6 km) in spite of the low magnitude of the eclipse. The reflection height at Kagoshima seems be divided into two parts: propagation across the total solar eclipse path and propagation in the partial solar eclipse path. During the eclipse, we also observed the phase variation in the LF transmitter signals. The average change in the phase delay of the LF signals was 109 for the paths that crossed the eclipse path and 27 for the paths that did not cross the eclipse path. Assuming a normal daytime height for LF waves of 65 km, a ray tracing analysis indicates that the variations in phase correspond to a height increase of 5-6 km for the paths across the eclipse and 1-2 km for partial eclipse paths. The wide range of estimated tweek reflection heights at Kagoshima also suggests a difference in electron density in the lower ionosphere between total and partial solar eclipses.

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“…In more recent works (see, e.g., De et al, , ; Guha et al, ) the eclipse's effects on the equatorial lower ionosphere were reported for the total solar eclipse on 22 July 2009. The signals from different transmitters were registered in India.…”

Section: Introductionmentioning

confidence: 92%

The Effect of the 21 August 2017 Total Solar Eclipse on the Phase of VLF/LF Signals

Рожной

Solovieva

Шалимов

et al. 2020

Earth and Space Science

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An experimental study of the phase and amplitude observations of sub‐ionospheric very low and low frequency (VLF/LF) signals is performed to analyze the response of the lower ionosphere during the 21 August 2017 total solar eclipse in the United States of America. Three different sub‐ionospheric wave paths are investigated. The length of the paths varies from 2,200 to 6,400 km, and the signal frequencies are 21.4, 25.2, and 40.75 kHz. The two paths cross the region of the total eclipse, and the third path is in the region of 40–60% of obscuration. None of the signals reveal any noticeable amplitude changes during the eclipse, while negative phase anomalies (from −33° to −95°) are detected for all three paths. It is shown that the effective reflection height of the ionosphere in low and middle latitudes is increased by about 3–5 km during the eclipse. Estimation of the electron density change in the lower ionosphere caused by the eclipse, using linear recombination law, shows that the average decrease is by 2.1 to 4.5 times.

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Effects of a Solar Eclipse on the Propagation of VLF-LF Signals: Observations and Results

Cited by 14 publications

References 35 publications

Spectral character of VLF sferics propagating inside the Earth‐ionosphere waveguide during two recent solar eclipses

Spectral character of VLF sferics propagating inside the Earth‐ionosphere waveguide during two recent solar eclipses

Reflection height of daytime tweek atmospherics during the solar eclipse of 22 July 2009

The Effect of the 21 August 2017 Total Solar Eclipse on the Phase of VLF/LF Signals

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