The detection of daytime nuclear bursts below 150 km by prompt VLF phase anomalies

Field, E. C.; Engel, Rainer M.E.

doi:10.1109/proc.1965.4477

Cited by 15 publications

(7 citation statements)

References 6 publications

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“…This departure from the ideal model can be partially explained by the fact that the reflection height for 1-10 kHz waves changes slightly with frequency. Analysis of the frequency-dependent reflection height is nontrivial and was investigated extensively in the 1960s and 1970s [Field and Engel, 1965;Bannister, 1979]. We note that some more contemporary published approaches like that of Ohya et al [2003], who ignore the high collision frequency in the D region, are not accurate in the ELF/VLF bands.…”

Section: Frequency Shift and Variability Of Resonance Peaksmentioning

confidence: 97%

“…We note that some more contemporary published approaches like that of Ohya et al [], who ignore the high collision frequency in the D region, are not accurate in the ELF/VLF bands. Using the formulations provided by Field and Engel [] and Bannister [], the physical reflection height occurs where the conduction current is equal to the displacement current or at an altitude z where

ω = \frac{ω_{p}^{2} (z)}{ν (z) \cos (θ_{i})}

…”

Section: Observationsmentioning

confidence: 99%

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Multistation observations of the azimuth, polarization, and frequency dependence of ELF/VLF waves generated by electrojet modulation

et al. 2015

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Modulated ionospheric heating experiments are performed with the High Frequency ActiveAuroral Research Program facility in Gakona, Alaska, for the purpose of generating extremely low frequency (ELF) and very low frequency (VLF) waves. Observations are made at three different azimuths from the heating facility and at distances from 37 km to 99 km. The polarization of the observed waves is analyzed in addition to amplitude as a function of modulation frequency and azimuth. Amplitude and eccentricity are observed to vary with both azimuth and distance from the heating facility. It is found that waves radiated at azimuths northwest of the facility are generated by a combination of modulated Hall and Pedersen currents, while waves observed at other azimuths are dominated by modulated Hall currents. We find no evidence for vertical currents contributing to ground observations of ELF/VLF waves. Observed amplitude peaks near multiples of 2 kHz are shown to result from vertical resonances in the Earth-ionosphere waveguide, and variations of the frequency of these resonances can be used to determine the D region ionosphere electron density profile in the vicinity of the HF heater.

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Section: Frequency Shift and Variability Of Resonance Peaksmentioning

confidence: 97%

ω = \frac{ω_{p}^{2} (z)}{ν (z) \cos (θ_{i})}

…”

Section: Observationsmentioning

confidence: 99%

Multistation observations of the azimuth, polarization, and frequency dependence of ELF/VLF waves generated by electrojet modulation

et al. 2015

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“…Localized ionospheric disturbances can also disrupt VLF propagation and electrons from the magnetosphere, dumped into the ionosphere by wave-particle interactions involving whistlers, have been found to affect VLF propagation [Helliwell et al, 1973;Lohrey and Kaiser, 1979]. Man-made localized ionospheric disturbances have also been produced, and in the early 1960's, much theoretical and experimental work was undertaken on the effects of atmospheric nuclear explosions both directly on and adjacent to VLF propagation paths [Wait, 1961[Wait, , 1964aCrombie, 1964;Jean and Crombie, 1963;Field and Engel, 1965].…”

Section: Introductionmentioning

confidence: 99%

The diffraction of VLF radio waves by a patch of ionosphere illuminated by a powerful HF transmitter

Barr¹,

Rietveld

Stubbe

et al. 1985

J. Geophys. Res.

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At Skibotn in northern Norway, measurements have been made of the effect of powerful HF waves, from the heating facility at Ramfjordmoen, on the propagation of VLF waves from the Omega transmitter (12.1 kHz) near Aldra and on the 16.4-kHz transmissions (JXN) at Helgeland. The HF beam was deflectable in a north-south direction, which enabled it to intersect the VLF propagation path. The VLF amplitude and phase perturbations were found to oscillate about zero as the beam was scanned across the propagation path, and typical daytime amplitude and phase perturbations had maximum magnitudes of ~0.1 dB and 0.5 ø. The maximum values appeared when the heated beam was symmetrically located across the VLF path. A study of the temporal variability of the amplitude and phase perturbations at a fixed-beam deflection angle (38øS) showed that large enhancements of up to two orders of magnitude occurred in the amplitude and phase perturbations at times when the total received VLF field strength passed through a minimum. Maximum amplitude and phase perturbations of 6 dB and 50 ø were recorded during one such minimum in the total received signal. Theoretical computations are presented which evaluate the diffracting effect of a heated patch of auroral ionosphere on multimode propagation in the earth-ionosphere waveguide. Computations of propagation under a series of ionospheres ranging from typical daytime to nighttime have been made, and the normal and enhanced amplitude and phase perturbations have been successfully modeled. Attempts at reproducing the perturbing effects of a mobile heated patch have not been nearly so successful, especially at large deflection angles. 1982a; Gurevich and Migulin, 1982]. These have provided, for the first time, an ability to study the effect of a controlled •On leave from Geophysical Observatory, D.S.I.R., Christchurch, New Zealand. ionospheric anomaly on the propagation of VLF waves. Jones et al. [1972] used the fixed-beam 50-MW heater at Platteville, Colorado, to modify the propagation of VLF and LF radio waves. They observed small changes in both phase and amplitude of the low-frequency waves coincident with the operation of the heating facility. More recently, Barr et al. [1984], using the Max-Planck heating facility near TromsO in Norway, have been able to make the first observations of the effect of a movable ionospheric anomaly on VLF propagation. Again, however, the effects were of a small scale (typically +0.1 dB of amplitude and _+0.5 ø in phase), but clear diffraction effects similar to those predicted by Wait [1964b] and Crombie [1964] were observed. Using the Arecibo heating facility, Kelly and Rao [1982] observed the effects of the HF heater on LF propagation, and they observed amplitude perturbations up to 10 dB occurring at a time of minimum received LF field strength. They explained these enhanced effects in terms of multipath interference within the ionosphere.The new data presented here describe the effects of the heating facility at Troms½ on the propagation of VLF radio waves...

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“…The experimental data in this section were obtained using a disturbed ionosphere which simulated the effect of a low yield nuclear burst at 40 km. The profile for the ionospheric perturbation was obtained from the paper by Field and Engel [1965].…”

Section: Effect Of a Small Nuclear Weapon Perturbation On Radio Propamentioning

confidence: 99%

A Laboratory Model for VLF Propagation Experiments

Schwartz¹,

Brown²

1971

Radio Science

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A laboratory model of a section of the earth‐ionosphere has been designed and constructed to provide a means for systematically investigating the effect of ionospheric perturbations on long range VLF paths. This model provides a capability for the investigation of a wide variety of different disturbed ionospheric conditions. For any given configuration, all the pertinent parameters are clearly defined and repeatable. This is in contradistinction to naturally occurring events, for which many parameters that are important for a clear interpretation are either unknown or, at best, poorly known. The design rationale and the construction methods are presented in this paper with initial experimental data obtained from the model for uniform propagation paths. It is shown that these data are in good agreement with theoretical data obtained for the modeled conditions. Data are also presented for propagation paths through a nuclear type ionospheric perturbation. These data exhibit both amplitude loss and phase advance caused by the perturbation.

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The detection of daytime nuclear bursts below 150 km by prompt VLF phase anomalies

Cited by 15 publications

References 6 publications

Multistation observations of the azimuth, polarization, and frequency dependence of ELF/VLF waves generated by electrojet modulation

Multistation observations of the azimuth, polarization, and frequency dependence of ELF/VLF waves generated by electrojet modulation

The diffraction of VLF radio waves by a patch of ionosphere illuminated by a powerful HF transmitter

A Laboratory Model for VLF Propagation Experiments

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