Doppler shift simulation of scattered HF signals during the Tromsø HF pumping experiment on 16 February 1996

Борисова, Т. Д.; Blagoveshchenskaya, N. F.; Moskvin, I. V.; Rietveld, M. T.; Kosch, M. J.; Thidé, Bo

doi:10.5194/angeo-20-1479-2002

Cited by 20 publications

(10 citation statements)

References 13 publications

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“…Simulation results of the Doppler frequencies shifts of scattered signals for the London-Tromsø-St. Petersburg path intimate that the velocity component in the north-south direction is crucial in the Doppler frequency shift values (Borisova et al, 2002). The positive Doppler frequency shifts (+f d ) correspond to the southward motions of AFAIs in the HF heater-induced scattering volume.…”

Section: Observational Results At Auroral Latitudesmentioning

confidence: 99%

“…Figure 8 shows the behaviour of the simulated f d , depending on the velocity direction on the ArmavirSura-St. Petersburg path (f =15 455 kHz), as well as on the Serpukhov-Sura-Kharkov and Serpukhov (Moscow)-SuraRostov paths at 11 630 (14 996) kHz. The simulation was made by using the model described by Borisova et al (2002). From Fig.…”

Section: Simulation Resultsmentioning

confidence: 99%

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Probing of medium-scale traveling ionospheric disturbances using HF-induced scatter targets

et al. 2006

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Abstract.Experimental results from the Tromsø and Sura heating experiments at high and mid-latitudes are examined. It is shown that the combination of HF-induced target and bi-static HF Doppler radio scatter observations is a profitable method for probing medium-scale traveling ionospheric disturbances (TIDs) at high and mid-latitudes. HF ionospheric modification experiments provide a way of producing the HF-induced scatter target in a controlled manner at altitudes where the sensitivity to TIDs is highest. Bi-static HF Doppler radio scatter observations were carried out on the LondonTromsø-St. Petersburg path in the course of a Tromsø heating experiment on 16 November 2004 when the pump wave was reflected from an auroral Es-layer. During Sura heating experiments on 19 and 20 August 2004, when the HF pump wave was reflected from the F2 ionospheric layer, multiposition bi-static HF Doppler radio scatter observations were simultaneously performed at three reception points including St. Petersburg, Kharkov, and Rostov-on-Don. Ray tracing and Doppler shift simulations were made for all experiments. A computational technique has been developed allowing the reconstruction of the TID phase velocities from multi-position bi-static HF Doppler scatters. Parameters of medium-scale TIDs were found. In all experiments they were observed in the evening and pre-midnight hours. TIDs in the auroral E-region with periods of about 23 min were traveling southward at speeds of 210 m/s. TIDs in the mid-latitudinalCorrespondence to: N. F. Blagoveshchenskaya (nataly@aari.nw.ru) F-region with periods from 20 to 45 min travelled at speeds between 40 and 150 m/s. During quiet magnetic conditions the waves were traveling in the north-east direction. In disturbed conditions the waves were moving in the south-west direction with higher speeds as compared with quiet conditions. Possible sources for the atmospheric gravity waves at middle and high latitudes are discussed.

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Section: Observational Results At Auroral Latitudesmentioning

confidence: 99%

Section: Simulation Resultsmentioning

confidence: 99%

Probing of medium-scale traveling ionospheric disturbances using HF-induced scatter targets

et al. 2006

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“…11). Calculations were performed for the HF pumping facilities EISCAT/HEATING (on the London -Tromsø -St. Petersburg path at f = 17640 kHz and on the PoriTromsø -St. Petersburg path at f = 11755 kHz ) and "Sura" (on the Armavir -"Sura" -St. Petersburg path at f = 15600 kHz), following model [26]. The values f d were calculated for the velocity V = 50 m/s of irregularities in the scattering volume.…”

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

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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.

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“…The scattered-signal frequency has a zero shift f d when the velocity vector of the irregularities over SPEAR is east-west-oriented. Then, following the model [24], the propagation paths of diagnostic signals during their scattering by AFAIs over SPEAR were modelled. The calculations were performed for geophysical conditions corresponding to the conditions of the SPEAR heating experiments.…”

Section: Behavior Of Small-scale Artificial Field-aligned Irregularitmentioning

confidence: 99%

The polar-ionosphere phenomena induced by high-power radio waves from the spear heating facility

Blagoveshchenskaya

Борисова

Kornienko

et al. 2008

Radiophys Quantum El

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We present the results of experimental studies of specific features in the behavior of small-scale artificial field-aligned irregularities (AFAIs) and the DM component in the spectra of stimulated electromagnetic emission (SEE). Analysis of experimental data shows that AFAIs in the polar ionosphere are generated under different background geophysical conditions (season, local time, the presence of sporadic layers in the E region, etc.). It is shown that AFAIs can be excited not only in the F region, but also in "thick" sporadic E s layers of the polar ionosphere. The AFAIs were observed in some cycles of heating when the HF heater frequency exceeded the critical frequency by 0.3−0.5 MHz. Propagation paths of diagnostic HF radio waves scattered by AFAIs were modelled for geophysical conditions prevailing during the SPEAR heating experiments. Two components, namely, a narrow-banded one with a Doppler-spectrum width of up to 2 Hz and a broadband one observed in a band of up to 20 Hz, were found in the sporadic E s layer during the AFAI excitation. Analysis of the SEE spectra shows that the behavior of the DM component in time is irregular, which is possibly due to strong variations in the critical frequency of the F 2 layer from 3.5 to 4.6 MHz. An interesting feature observed in the SPEAR heating experiments is that the generation of the DM component was similar to the excitation of AFAIs when the heater frequency was up to 0.5 MHz higher than the critical frequency.

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Doppler shift simulation of scattered HF signals during the Tromsø HF pumping experiment on 16 February 1996

Cited by 20 publications

References 13 publications

Probing of medium-scale traveling ionospheric disturbances using HF-induced scatter targets

Probing of medium-scale traveling ionospheric disturbances using HF-induced scatter targets

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

The polar-ionosphere phenomena induced by high-power radio waves from the spear heating facility

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