Significance of field-aligned currents for F-region perturbations

Kagan, L. M.; Frolov, V. L.

doi:10.1016/0021-9169(95)00155-7

Cited by 16 publications

(12 citation statements)

References 22 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Such an attenuation of the additional-heating influence can be related to both an increase in the distance between the DW and PW reflection points up to 35 km as the PW frequency approched the critical frequency of the ionospheric F 2 layer and a possible decrease in the action efficiency due to partial "penetration" of the PW energy through the ionosphere. Also, the influence of other reasons related, for example, to specific features of the sunset variations in the DSEE intensity [25], is not excluded. It is fairly difficult to separate the influence of these factors without additional special test measurements.…”

Section: Effects Observed During Short-pulse Actionmentioning

confidence: 99%

On the effects observed during modification of the earth’s upper ionosphere by high-power short radio pulses

Frolov

Комраков

Nedzvetsky

et al. 2006

Radiophys Quantum Electron

View full text Add to dashboard Cite

We report on the results of studies of the evolution of artificial ionospheric turbulence (AIT) excited by short pulses of high-power short-wave O-mode radio emission in the ionospheric F region. On the basis of the obtained experimental data, it is assumed that the streams of thermal and suprathermal electrons generated in the regions of resonant interaction between a high-power radio wave and the plasma and propagating along the geomagnetic field stimulate the development of plasma perturbations far away from the primary-turbulence regions. Specific features of the measurement procedure are considered, an empirical model of the observed phenomena is developed, and possible problems in the further studies are outlined.

show abstract

Section: Effects Observed During Short-pulse Actionmentioning

confidence: 99%

On the effects observed during modification of the earth’s upper ionosphere by high-power short radio pulses

Frolov

Комраков

Nedzvetsky

et al. 2006

Radiophys Quantum Electron

View full text Add to dashboard Cite

show abstract

“…A detailed description of this experiment and its results can be found in [2,15], and the following conclusions on its basis can be drawn:…”

Section: Results Of the Measurements Performed In March 1990mentioning

confidence: 97%

On specific features of diurnal variations in characteristics of the diagnostic stimulated electromagnetic emission and their relation to the evolution of artificial ionospheric irregularities

Frolov

Vertogradov²,

Vertogradov³

2008

Radiophys Quantum El

View full text Add to dashboard Cite

We analyze variations in characteristics of the diagnostic stimulated electromagnetic emission of the ionosphere in the evening hours including the times of sunset both on the Earth's surface at the observation point and in the ionosphere over it. It is found that an increase in typical times of evolution of the diagnostic emission begins to be recorded just before the sunset on the Earth's surface when the ionosphere is illuminated and its parameters are not significantly changed yet. We state that the typical times of evolution of the diagnostic emission increase when the pumpwave frequency approaches the critical frequency of the ionospheric F 2 layer, but such an effect is not as significant as when passing from the illuminated to the unilluminated ionosphere. It is established that at the stage of diagnostic sounding the pump-wave pulse power does not exert any notable influence on the first (fast) stage of relaxation of small-scale artificial ionospheric irregularities, but can increase the decay time of the irregularities at the second (slow) stage of relaxation. Capabilities of the method for a study of artificial plasma turbulence using the diagnostic stimulated electromagnetic emission are discussed.

show abstract

“…The behavior of aspect-scattered signals at the stage of their slow relaxation shows quasi-periodic variations in f d stipulated by Pc3-4 geomagnetic pulsations and passage of middle-scale traveling ionospheric disturbances over the "Sura" facility. Slow relaxation of irregularities is explained either by the influence of natural perturbations in a plasma (the enhancement of natural ionospheric irregularities with the scales l ⊥ > 100 m in the evening and night-time hours) or by the conversion of energy over the spectrum of artificial ionospheric turbulence from larger to smaller scales [6,22,27,28]. It is also assumed [22] that the electric field of the Alfvén wave in the scattering volume, which reaches a few millivolts per meter, can also maintain the existence of irregularities.…”

Section: Discussion Of Resultsmentioning

confidence: 99%

Some distinctive features in the behavior of small-scale artificial ionospheric irregularities at mid-and high latitudes

Blagoveshchenskaya

Борисова

Kornienko

et al. 2007

Radiophys Quantum El

View full text Add to dashboard Cite

We present the results of experimental studies of some features in the behavior of small-scale artificial irregularities (SSAIs) at mid-and high latitudes based on the "Sura" and EISCAT/ HEATING HF facilities. Observations were performed by the method of aspect scattering using a network of diagnostic paths having a common reception point located near St. Petersburg. We found that an extremely long duration of the second (slow) stage of SSAI relaxation of up to 5 min occurs in the evening hours when the ionosphere above the "Sura" facility is illuminated by the Sun, but the solar terminator travels through the magnetically conjugated ionosphere. The conjecture is made that the processes initiated by the terminator are mostly responsible for secondary ionospheric turbulence maintaining the irregularities above "Sura." A drastic increase in the Doppler spectra width of the scattered signals is revealed when the magnetically conjugate point of the ionosphere is located on the shade side of the terminator, but the ionosphere above the "Sura" facility is still lighted. It is assumed that the "run away" of photoelectrons from the day to the night side could reduce the threshold of excitation of artificial irregularities, leading to an increase in their intensity. The presence of fairly intense scattered signals was detected from the "Sura" and EISCAT/HEATING experimental results both under conditions of pulsed HF heating after continuous heater-on periods and cycled HF heating by short pulses. In the case of pulsed heating by short pulses with duration τ p < 100 ms and average radiated power P a below the threshold power P thr of the SSAI generation cutoff the irregularities can be maintained due only to striction parametric instabilities. The excitation of irregularites under the cycled HF pumping with the pulse duration τ p = 384 ms for P a comparable with P thr was detected. The aspect-angle dependence, or the so-called magnetic zenith effect, was found in the SSAI intensity. The residual turbulence aftereffects played a significant role in the SSAI development.

show abstract

Significance of field-aligned currents for F-region perturbations

Cited by 16 publications

References 22 publications

On the effects observed during modification of the earth’s upper ionosphere by high-power short radio pulses

On the effects observed during modification of the earth’s upper ionosphere by high-power short radio pulses

On specific features of diurnal variations in characteristics of the diagnostic stimulated electromagnetic emission and their relation to the evolution of artificial ionospheric irregularities

Some distinctive features in the behavior of small-scale artificial ionospheric irregularities at mid-and high latitudes

Contact Info

Product

Resources

About