Total solar eclipse effects on VLF signals: Observations and modeling

Clilverd, Mark A.; Rodger, Craig J.; Thomson, Neil R.; Lichtenberger, János; Steinbach, Péter; Cannon, Paul S.; Angling, Matthew

doi:10.1029/2000rs002395

Cited by 97 publications

(127 citation statements)

References 19 publications

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“…The TRGCPs for five selected stations in the study vary between~400 and 7600 km (Table 1) and can be classified as short (<1000 km) and medium (1000-10,000 km) paths [Clilverd et al, 2001]. Clilverd et al [2001] for 11 August 1999 total SE observed both positive (increase) and negative (decrease) VLF amplitude changes (and in some cases both) which for majority of short paths were positive and negative for long paths. During 22 July 2009 total SE, Guha et al…”

Section: Experimental Setup and Datamentioning

confidence: 99%

“…discontinuty created by SE shadow [Clilverd et al, 2001] which depends mainly on the TRGCP length, path direction, topography of receiver sites, SE conditions, and ionospheric conditions along the TRGCP. The sudden increase in the D region reflection height due to SE causes some more significant modes reaching to receving stations and resulting in a complex interference pattern [Clilverd et al, 2001] of modes at the receiver sites.…”

Section: 1002/2013ja019521mentioning

confidence: 99%

“…The sudden increase in the D region reflection height due to SE causes some more significant modes reaching to receving stations and resulting in a complex interference pattern [Clilverd et al, 2001] of modes at the receiver sites.…”

Section: 1002/2013ja019521mentioning

confidence: 99%

“…There are several investigations on the Earth's atmospheric and ionospheric effects of SEs [e.g., Boyd, 1966;Anderson et al, 1972;Antonia et al, 1979;Srivastava et al, 1982;Chimonas and Hines, 1970;Chimonas, 1970;Clilverd et al, 2001;Babakhanov et al, 2013 and references therein]. Further studies on SEs ionospheric effects (particularly in lower ionosphere) are warranted because of the fact that each eclipse is different from others based on the occurrence time of the year, time of the day, degree of the solar disk occultation, state of the space, and atmospheric weather and location (latitude and longitude) of observations on the Earth [Baran et al, 2003].…”

Section: Introductionmentioning

confidence: 99%

“…density ionosonde cannot receive echoes; hence, the D region remains the least explored region of the Earth's ionosphere. Fixed very low frequency (VLF) narrowband signals from various VLF transmitters located across the world propagate by multiple reflections through the waveguide formed by the Earth and the lower ionosphere called Earth-ionosphere waveguide (EIWG) and form the novel tools for continuous monitoring of the D region ionosphere [Clilverd et al, 2001].…”

Section: Introductionmentioning

confidence: 99%

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Low‐mid latitude D region ionospheric perturbations associated with 22 July 2009 total solar eclipse: Wave‐like signatures inferred from VLF observations

Maurya¹,

Phanikumar

Singh³

et al. 2014

JGR Space Physics

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We present first report on the periodic wave-like signatures (WLS) in the D region ionosphere during 22 July 2009 total solar eclipse using JJI, Japan, very low frequency (VLF) navigational transmitter signal (22.2 kHz) observations at stations, Allahabad, Varanasi and Nainital in Indian Sector, Busan in Korea, and Suva in Fiji. The signal amplitude increased on 22 July by about 6 and 7 dB at Allahabad and Varanasi and decreased by about 2.7, 3.5, and 0.5 dB at Nainital, Busan, and Suva, respectively, as compared to 24 July 2009 (normal day). The increase/decrease in the amplitude can be understood in terms of modal interference at the sites of modes converted at the discontinuity created by the eclipse intercepting the different transmitter-receiver great circle paths. The wavelet analysis shows the presence of WLS of period~16-40 min at stations under total eclipse and of period~30-80 min at stations under partial eclipse (~85-54% totality) with delay times between~50 and 100 min at different stations. The intensity of WLS was maximum for paths in the partially eclipsed region and minimum in the fully eclipsed region. The features of WLS on eclipse day seem almost similar to WLS observed in the nighttime of normal days (e.g., 24 July 2009). The WLS could be generated by sudden cutoff of the photo-ionization creating nighttime like conditions in the D region ionosphere and solar eclipse induced gravity waves coming to ionosphere from below and above. The present observations shed additional light on the current understanding of gravity waves induced D region ionospheric perturbations.

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Section: Experimental Setup and Datamentioning

confidence: 99%

Section: 1002/2013ja019521mentioning

confidence: 99%

Section: 1002/2013ja019521mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Low‐mid latitude D region ionospheric perturbations associated with 22 July 2009 total solar eclipse: Wave‐like signatures inferred from VLF observations

Maurya¹,

Phanikumar

Singh³

et al. 2014

JGR Space Physics

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Effect of the total solar eclipse of 20 March 2015 on the ELF propagation over high‐latitude paths

Tereshchenko

Sidorenko

Tereshchenko

et al. 2015

Geophysical Research Letters

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Propagation of the artificial electromagnetic waves with frequency of 82 Hz in the Earth‐ionosphere waveguide was observed during the solar eclipse on both partially and totally obscured high‐latitude paths with a length of 450–1200 km. Field excitation was monitored by the reference measurements in the near zone of the transmitter, which are free of the ionospheric influence. It is found that the amplitude of the field at the remote points varied depending on the solar illumination and solar elevation angle. We suppose that this effect was probably caused by the increase in the effective height of the ionospheric D layer, just as it was previously observed in VLF. The obtained results demonstrate the response of the propagating extremely low frequency (ELF, 3–300 Hz) wave to the change in the ionospheric boundary. This effect has been for the first time observed in this frequency range during a total solar eclipse.

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Classifying onset durations of early VLF events: Scattered field analysis and new insights

Kotovsky

Moore

2015

JGR Space Physics

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The physical processes responsible for a variety of early VLF scattering events have not yet been satisfactorily identified. Properly categorizing the early VLF event type is imperative to understand the causative physical processes involved. In this paper, the onset durations of 26 exceptionally high signal‐to‐noise ratio early VLF scattering events are analyzed, using scattered fields to classify events. New observations of events that exhibit “slow” amplitude changes, but “fast” scattered field changes are presented, which call into question previous analyses of early/slow events. We separately identify and analyze three early VLF events that definitively exhibit slow scattered field behavior. Additionally, we identify a significant number of events which have onset durations between the current definitions of fast and slow. Four events are observed which unambiguously exhibit a rapid initial rotation of the scattered field phasor during the first few seconds of the recovery stage. Possible physical mechanisms are discussed.

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Total solar eclipse effects on VLF signals: Observations and modeling

Cited by 97 publications

References 19 publications

Low‐mid latitude D region ionospheric perturbations associated with 22 July 2009 total solar eclipse: Wave‐like signatures inferred from VLF observations

Low‐mid latitude D region ionospheric perturbations associated with 22 July 2009 total solar eclipse: Wave‐like signatures inferred from VLF observations

Effect of the total solar eclipse of 20 March 2015 on the ELF propagation over high‐latitude paths

Classifying onset durations of early VLF events: Scattered field analysis and new insights

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