Solar eclipse effects on HF and VLF propagation

Meisel, D. D.; Duke, Basil; Aguglia, Robert C; Goldblatt, Norman R

doi:10.1016/0021-9169(76)90006-4

Cited by 4 publications

(3 citation statements)

References 13 publications

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“…Turbulence effects in the D-region and VLF NB measurements during a solar eclipse event were already speculated a few decades ago by Meisel et al [1976]. More recently, Chernogor [2010] reported an intensification of oscillations with time periods of 10-15 and 18 min based on spectral analysis of VLF NB amplitude and phase data during a solar eclipse.…”

Section: Solar Eclipsementioning

confidence: 88%

On the Use of VLF Narrowband Measurements to Study the Lower Ionosphere and the Mesosphere–Lower Thermosphere

Silber

Price

2016

Surv Geophys

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The ionospheric D-region (~60 km up to ~95 km) and the corresponding neutral atmosphere, often refered to as the mesosphere-lower-thermosphere (MLT) are challenging and costly to probe in-situ. Therefore, remote sensing techniques have been developed over the years. One of these is based on VLF (Very low frequency, 3-30 kHz) electromagnetic waves generated by various natural and manmade sources. VLF waves propagate within the Earth-ionosphere waveguide, and are extremely sensitive to perturbations occurring in the D-region along their propagation path. Therefore, measurements of these signals serve as an inexpensive remote sensing technique for probing the lower ionosphere and the MLT region. This paper reviews the use of VLF narrowband (NB) signals (generated by man-made transmitters) in the study of the D-region and the MLT for over 90 years. The fields of research span time scales from microseconds to decadal variability, and incorporate lightning-induced short term perturbations; extraterrestrial radiation bursts; energetic particle precipitation events; solar eclipses; lower atmospheric waves penetrating into the D-region; sudden stratospheric warming events; the annual oscillation; the solar cycle; and finally, the potential use of VLF NB measurements as an anthropogenic climate change monitoring technique.

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Section: Solar Eclipsementioning

confidence: 88%

On the Use of VLF Narrowband Measurements to Study the Lower Ionosphere and the Mesosphere–Lower Thermosphere

Silber

Price

2016

Surv Geophys

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“…reverberation of hydromagnetic waves. Indeed, it was shown indirectly that the 1972 Eo event was accompanied by such mideclipse disturbances [Meisel et al, 1976]. A future autocorrelation study of aa' indices followed by an appropriate t test analysis should be able to test this suggestion (which is somewhat at variance with the conclusions of our previous statistical analyses based on the assumption of uncorrelated Ci values) in more detail.…”

Section: To Obtain Our Minimax Model We Assume That In All Cases Thementioning

confidence: 89%

Search for worldwide solar eclipse perturbations of geomagnetic activity 1906–1976: Lunar modulation of Ci revisited

Meisel¹,

Blazejewski²

1979

J. Geophys. Res.

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Solar eclipses occur with periodicities of 29.53 days, 6 months, 8.85 years, and 18.6 years. Since these are nearly commensurate with known solar‐terrestrial event repetition cycles (27.3 days, semiannual, and 11 years), searches for possible solar eclipse effects in daily geophysical data using standard autocorrelation techniques are likely to have serious side‐band interference problems. Therefore a survey of the geomagnetic Ci index for the years 1906–1976 (164 eclipses) was performed by using a modified version of the well‐known t test for the difference of two means to define eclipse departure probability (Pd). Eclipse epoch Ci changes are shown to satisfy a simple probabilistic model composed of two events—one due to the eclipse E and another due to a ‘background’ of zero ecliptic latitude Ci fluctuations ZL such that the mean values of the departure probabilities are 〈Pd(E|ZL)〉 = 0.5±0.1, 〈Pd(E)〉 = 0.3 ± 0.1, and 〈Pd(ZL|E)〉 = (1.8±0.2)〈Pd(ZL)〉. It is also shown that the derived 〈Pd(E)〉 value is consistent with a simple statistical occulation model and the Pd derived from geomagnetic effects observed during one total solar eclipse. The large and persistent conditional probabilities, however, appear to require some sort of geomagnetic reverberation effect between the earth and moon.

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“…The change in height of the D-region during a solar eclipse is followed by amplitude variations of the VLF-LF signals propagated through the Earth-ionosphere waveguide. Meisel et al (1976) described a multifrequency oblique-incidence experiment performed during the total solar eclipse of 10 July 1972. They observed a correlation among VLF phase, HF signal strength and geomagnetic field.…”

Section: Introductionmentioning

confidence: 99%

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

De¹,

De²,

Bandyopadhyay³

et al. 2011

Terr. Atmos. Ocean. Sci.

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The results from the measurements of some of the fundamental parameters (amplitude of sferics and transmitted signal, conductivity of lower ionosphere) of the ionospheric responses to the 22 July 2009 solar eclipse (partial: 91.7%) are shown. This study summarizes our results from sferics signals at 81 kHz and subionospheric transmitted signals at 19.8 and 40 kHz recorded at Agartala, Tripura (latitude: 23°N, longitude: 91.4°E). We observed significant absorption in amplitude of these signals during the eclipse period compared to their ambient values for the same period during the adjacent 7 days. The signal strength along their propagation paths was controlled by the eclipse associated decrease in ionization in the D-region of the ionosphere. Waveguide mode theory calculations show that the elevation of the height of lower ionosphere boundary of the Earth-ionosphere waveguide to a value where the conductivity parameter was 10 6 unit. The absorption in 81 kHz sferics amplitude is high compared to the absorption in the amplitude of 40 kHz signal transmitted from Japan. The simultaneous changes in the amplitudes of sferics and in the amplitude of transmitted signals assert some sort of coupling between the upper atmosphere and the Earth's near-surface atmosphere prevailing clouds during solar eclipse.

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Solar eclipse effects on HF and VLF propagation

Cited by 4 publications

References 13 publications

On the Use of VLF Narrowband Measurements to Study the Lower Ionosphere and the Mesosphere–Lower Thermosphere

On the Use of VLF Narrowband Measurements to Study the Lower Ionosphere and the Mesosphere–Lower Thermosphere

Search for worldwide solar eclipse perturbations of geomagnetic activity 1906–1976: Lunar modulation of Ci revisited

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

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