Artificial field-aligned irregularities in the nightside auroral ionosphere

Blagoveshchenskaya, N. F.; Борисова, Т. Д.; Kornienko, V. N.; Leyser, T. B.; Rietveld, M. T.; Thidé, Bo

doi:10.1016/j.asr.2004.12.008

Cited by 19 publications

(22 citation statements)

References 22 publications

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“…The same result was obtained by Blagoveshchenskaya et al (1999Blagoveshchenskaya et al ( , 2006a when strong heaterinduced striations were observed in the auroral E-region with bi-static HF radio scatter. Striations have also been observed from Tromsø HF heating experiments in the night-side Fregion of the auroral ionosphere when foF2 drops below the heater frequency by up to 0.5 MHz (Blagoveshchenskaya et al, 2006b). In all these studies the condition of the auroral ionosphere was monitored by ionosonde data.…”

Section: Introductionmentioning

confidence: 96%

“…The excitation of artificial small-scale field-aligned irregularities or striations (Minkoff et al, 1974;Djuth et al, 1985;Blagoveshchenskaya et al, 1999Blagoveshchenskaya et al, , 2006b), HF-induced electron heating (Rietveld et al, 2003) and airglow (Brandstrom et al, 1999;Pedersen and Carlson, 2001;Kosch et al, 2002), anomalous absorption (Robinson, 1989) and other phenomena occur at the upper hybrid resonance altitude in HF heating experiments when O-mode polarized HF pump waves reach the ionospheric reflection height. An O-mode HF pump wave couples through striations into electrostatic (upper hybrid) waves at the upper-hybrid resonance altitude, which is below the reflection height of the heating wave.…”

Section: Introductionmentioning

confidence: 99%

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Phenomena induced by powerful HF pumping towards magnetic zenith with a frequency near the F-region critical frequency and the third electron gyro harmonic frequency

Blagoveshchenskaya

Carlson²,

Kornienko

et al. 2009

Ann. Geophys.

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Abstract. Multi-instrument observational data from an experiment on 13 October 2006 at the EISCAT/HEATING facility at Tromsø, Norway are analysed. The experiment was carried out in the evening hours when the electron density in the F-region dropped, and the HF pump frequency f H was near and then above the critical frequency of the F2 layer. The distinctive feature of this experiment is that the pump frequency was just below the third electron gyro harmonic frequency, while both the HF pump beam and UHF radar beam were directed towards the magnetic zenith (MZ). The HF pump-induced phenomena were diagnosed with several instruments: the bi-static HF radio scatter on the LondonTromsø-St. Petersburg path, the CUTLASS radar in Hankasalmi (Finland), the European Incoherent Scatter (EIS-CAT) UHF radar at Tromsø and the Tromsø ionosonde (dynasonde). The results show thermal electron excitation of the HF-induced striations seen simultaneously from HF bi-static scatter and CUTLASS radar observations, accompanied by increases of electron temperature when the heater frequency was near and then above the critical frequency of the F2 layer by up to 0.4 MHz. An increase of the electron density up to 25% accompanied by strong HF-induced electron heating was observed, only when the heater frequency was near the critical frequency and just below the third electron gyro harmonic frequency. It is concluded that the combined effect of upper hybrid resonance and gyro resonance at the same altitude gives rise to strong electron heating, the excitation of Correspondence to: N. F. Blagoveshchenskaya (nataly@aari.nw.ru) striations, HF ray trapping and extension of HF waves to altitudes where they can excite Langmuir turbulence and fluxes of electrons accelerated to energies that produce ionization.

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Section: Introductionmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

Phenomena induced by powerful HF pumping towards magnetic zenith with a frequency near the F-region critical frequency and the third electron gyro harmonic frequency

Blagoveshchenskaya

Carlson²,

Kornienko

et al. 2009

Ann. Geophys.

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“…We report experimental results related to probing medium-scale traveling ionospheric disturbances using HF-induced scatter targets at mid-and high latitudes. With bi-static HF Doppler scatter, the AFAIs are being studied at middle (Blagoveshchenskaya and Troshichev, 1996;Yampolski et al, 1997;Blagoveshchenskaya et al, 1998a) and high latitudes (Blagoveshchenskaya et al, 1998b(Blagoveshchenskaya et al, , 1999(Blagoveshchenskaya et al, , 2006Rietveld et al, 2003). The proposed observational technique was used for the first time to identify the medium-scale TIDs.…”

Section: Introductionmentioning

confidence: 99%

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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“…The resulting expected deepening of the duct locally moves the upper hybrid resonance height upward. Since in the L-mode the wave electric field is perpendicular to B 0 at higher plasma densities than in the O-mode, the L-mode facilitates excitation of upper hybrid phenomena localized in the density depletions of small-scale striations (Vas'kov and Gurevich, 1976;Dysthe et al, 1982;Gurevich et al, 1995;Istomin and Leyser, 1997) and associated anomalous absorption deeper into the plasma (at higher ambient plasma densities) and in a wider altitude range than for pure Omode propagation. The duct, so to speak, tells the pump wave where to propagate and the pump wave tells the duct where to deepen, which may lead to self-focusing in magnetic zenith.…”

Section: Discussionmentioning

confidence: 99%

“…Experiments with the high-latitude EISCAT (European Incoherent SCATter association) high-power HF facility (named Heating) in northern Norway and the HAARP (High frequency Active Auroral Research Program) HF facility in Alaska, USA, show intensified optical emissions (Kosch et al, 2000;Pedersen and Carlson, 2001;Rietveld et al, 2003) and selffocusing (Gustavsson et al, 2001;Kosch et al, 2007) in magnetic zenith. Further, electron temperature enhancements are the largest when pumping near magnetic zenith (Rietveld et al, 2003;Honary et al, 2011) and pump-excited geomagnetic field-aligned density striations give the strongest HF-radar backscatter, as observed in experiments with EIS-CAT Heating (Rietveld et al, 2003;Blagoveshchenskaya et al, 2006), and the mid-latitude Sura HF facility in Russia (Tereshchenko et al, 2004). The question is, what causes the strong plasma response in magnetic zenith?…”

Section: Introductionmentioning

confidence: 99%

Evidence of <i>L</i>-mode electromagnetic wave pumping of ionospheric plasma near geomagnetic zenith

et al. 2018

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Abstract. The response of ionospheric plasma to pumping by powerful HF (high frequency) electromagnetic waves transmitted from the ground into the ionosphere is the strongest in the direction of geomagnetic zenith. We present experimental results from transmitting a left-handed circularly polarized HF beam from the EISCAT (European Incoherent SCATter association) Heating facility in magnetic zenith. The CASSIOPE (CAScade, Smallsat and IOnospheric Polar Explorer) spacecraft in the topside ionosphere above the F-region density peak detected transionospheric pump radiation, although the pump frequency was below the maximum ionospheric plasma frequency. The pump wave is deduced to arrive at CASSIOPE through L-mode propagation and associated double (O to Z, Z to O) conversion in pump-induced radio windows. L-mode propagation allows the pump wave to reach higher plasma densities and higher ionospheric altitudes than O-mode propagation so that a pump wave in the L-mode can facilitate excitation of upper hybrid phenomena localized in density depletions in a larger altitude range. L-mode propagation is therefore suggested to be important in explaining the magnetic zenith effect.

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Artificial field-aligned irregularities in the nightside auroral ionosphere

Cited by 19 publications

References 22 publications

Phenomena induced by powerful HF pumping towards magnetic zenith with a frequency near the F-region critical frequency and the third electron gyro harmonic frequency

Phenomena induced by powerful HF pumping towards magnetic zenith with a frequency near the F-region critical frequency and the third electron gyro harmonic frequency

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

Evidence of <i>L</i>-mode electromagnetic wave pumping of ionospheric plasma near geomagnetic zenith

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Artificial field-aligned irregularities in the nightside auroral ionosphere

Cited by 19 publications

References 22 publications

Phenomena induced by powerful HF pumping towards magnetic zenith with a frequency near the F-region critical frequency and the third electron gyro harmonic frequency

Phenomena induced by powerful HF pumping towards magnetic zenith with a frequency near the F-region critical frequency and the third electron gyro harmonic frequency

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

Evidence of &lt;i&gt;L&lt;/i&gt;-mode electromagnetic wave pumping of ionospheric plasma near geomagnetic zenith

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Evidence of <i>L</i>-mode electromagnetic wave pumping of ionospheric plasma near geomagnetic zenith