Monitoring of wave-like disturbances by means of oblique sounding of the ionosphere

Vertogradov

et al. 2007

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We present the results of experimental studies of the features of field-aligned scattering of HF radio waves for different angles of incidence of high-power radio waves on the ionosphere. The amplitude, Doppler frequency shift, and azimuthal and vertical arrival angles of the scattered signals are measured. Calculated ray paths in the magnetoactive ionosphere are compared with experimental data on the scattered-signal reception under conditions of action of high-power oblique radio waves on the ionosphere.

Section: Experiments Description and Observation Resultssupporting

confidence: 91%

Field-aligned scattering of HF radio waves under conditions of action of high-power oblique radio waves on the ionosphere

Vertogradov

et al. 2007

Self Cite

“…We assume that this effect is due to the influence of quisiperiodic traveling ionospheric disturbances. According to [5], wave disturbances with 20−90-min periods are almost constantly present on the studied paths. During a small geomagnetic perturbation in December 6, both the temporal correlation radius of the maximum observable frequency and the temporal shift ∆T , accompanied by the polarization sign reversal, decreased.…”

Section: Studying Temporal Variations In the Maximum Observable Frequmentioning

confidence: 92%

Spatio-temporal correlation of the maximum observable frequency on midlatitude radio lines

Бархатова

Vertogradov

et al. 2009

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We present the results of studying the spatial and temporal correlation of the maximum observable frequency on two midlatitude paths, Inskip (England)-Rostov-on-Don and Cyprus-Rostov-onDon. Dynamics of variation in the maximum observable frequency on these paths as a function of the time of the day and geophysical conditions is explored. The presence of a high spatial correlation (up to 93.5%) between the studied maximum observable frequencies allowed the values of the maximum observable frequency on the Cyprus-Rostov-on-Don path to be retrieved from the data on the Inskip-Rostov-on-Don path by the method of artificial neural networks with a training efficiency of up to 97%.

“…One way of determining the spatial distribution of the electron number density is solution of the inverse problem of retrieving the N e profile from the oblique sounding data obtained in real time [1]. In recent years, oblique sounding of the ionosphere has employed widely ionosondes with chirp modulation of the signal (CM ionosondes), which have a high interference protection and a high time resolution of group delay and frequency [2][3][4][5]. However, due to new tighter requirements for the parameters of radio engineering equipment operated under the conditions of a horizontally inhomogeneous ionosphere, it is insufficient to know only the distance-frequency characteristic (DFC) determined by means of a CM ionosonde in order to retrieve the distribution of the electron number density N e on the sounding path with an acceptable accuracy.…”

Section: Introductionmentioning

confidence: 99%

Sounding of an artificially perturbed ionosphere by means of an ionosonde/position finder with chirp modulation of the signal

Vertogradov²,

Vertogradov³

et al. 2009

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We describe the operation of an ionosonde/position finder with chirp modulation of the signal. The first results of measuring the characteristics of short-wave radio signals scattered by artificial small-scale inhomogeneities, which were obtained by means of an ionosonde/position finder on the IZMIRAN-"SURA"-Rostov-on-Don path are presented. It was found that under certain ionospheric conditions, the angular and frequency selection of the scattered signals take place, in which case the signals are observed simultaneously in several frequency intervals (mainly, in three, namely, 6-9.5 MHz, 10-12 MHz, and 15-18 MHz) with different angles of incidence of radio waves in the vertical plane. In this case, the incidence angles were 20 • -35 • , 18 • -32 • , and 10 • -20 • from the horizon for the first, second, and third frequency interval, respectively. Ionograms of oblique sounding were modeled allowing for the scattering of radio waves by artificial small-scale inhomogeneities. It is shown that at frequencies from 10 to 12 MHz, aspect conditions are fulfilled for the signals ducting along the high-angle beam (Pedersen mode). At frequencies 15-18 MHz (higher than the maximum observable frequency of the forward signal on the path IZMIRANRostov-on-Don), aspect scattering conditions are fulfilled for the signals incident on a scattering area in the ascending part of the trajectory. At low frequencies 6-9.5 MHz (below the maximum observed frequency of the forward signal on the IZMIRAN-Rostov-on-Don path), the observable additional signals are caused by the scattering of radio waves by artificial inhomogeneities with subsequent relfection of the scattered signal from the Earth on the "SURA"-Rostov-on-Don path.