Generation of large sheet‐like ionospheric plasma irregularities at Arecibo

Lee, M. C.; Riddolls, R.J.; Burke, William J.; Sulzer, M. P.; Kuo, Spencer; Klien, E. M. C.

doi:10.1029/98gl02322

Cited by 31 publications

(18 citation statements)

References 17 publications

(8 reference statements)

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“…FAIs generated by the X-mode heater are polarized in the meridian plane; on the other hand, O-mode heater generates sheet-like FAIs parallel to the meridian plane. 4 Thus, the FAIs generated by the O-mode heater are not effective to enhance virtual height spread of the sounding echo. Another mechanism of large-scale FAI generation is thermal instability.…”

Section: Discussionmentioning

confidence: 99%

“…Under the condition that (X e /x r ) 4 ( 1, the eigen-frequencies x r and x sr of the high frequency and low frequency plasma modes are derived to be x r ffi x kh ¼ ðx 2 p þ 3k 2 1 v 2 te þ X 2 e sin 2 hÞ 1=2 (A13) and…”

Section: Appendix: Formulation Of Parametric Couplingsmentioning

confidence: 99%

“…[1][2][3] Effective heating can cause noticeable ionospheric modification, [4][5][6][7][8][9] which reveals the linear and nonlinear properties of the ionospheric plasma. The majority of the HF heating experiments was focused on F region modification, where the collision frequencies are small and nonthermal processes prevail.…”

Section: Introductionmentioning

confidence: 99%

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Experiments and theory on parametric instabilities excited in HF heating experiments at HAARP

2014

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Parametric instabilities excited by O-mode HF heater and the induced ionospheric modification were explored via HAARP digisonde operated in a fast mode. The impact of excited Langmuir waves and upper hybrid waves on the ionosphere are manifested by bumps in the virtual spread, which expand the ionogram echoes upward as much as 140 km and the downward range spread of the sounding echoes, which exceeds 50 km over a significant frequency range. The theory of parametric instabilities is presented. The theory identifies the ionogram bump located between the 3.2 MHz heater frequency and the upper hybrid resonance frequency and the bump below the upper hybrid resonance frequency to be associated with the Langmuir and upper hybrid instabilities, respectively. The Langmuir bump is located close to the upper hybrid resonance frequency, rather than to the heater frequency, consistent with the theory. Each bump in the virtual height spread of the ionogram is similar to the cusp occurring in daytime ionograms at the E-F2 layer transition, indicating that there is a small ledge in the density profile similar to E-F2 layer transitions. The experimental results also show that the strong impact of the upper hybrid instability on the ionosphere can suppress the Langmuir instability. V C 2014 AIP Publishing LLC.

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Section: Discussionmentioning

confidence: 99%

Section: Appendix: Formulation Of Parametric Couplingsmentioning

confidence: 99%

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Experiments and theory on parametric instabilities excited in HF heating experiments at HAARP

2014

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“…All three nights suggest that O-mode CW heater operation may influence the local entry of VLF transmissions into preexisting or enhanced natural ducts. The I-IF heater is incapable of directly producing the large-scale and farreaching density perturbations necessary to duct very low frequencies interhemispherically, but it can significantly affect the local plasma environment where signals couple into the ionosphere, possibly altering the coupling efficiency of the bottomside ionosphere through the generation of largescale field-aligned irregularities and the depletion of magnetic flux tubes [Lee et al, 1998a[Lee et al, , 1998b[Lee et al, , 1999. It is then reasonable to expect that the heater might influence the local trapping of signals in existing ducts at higher altitudes.…”

Section: Long-delay Signalsmentioning

confidence: 99%

“…Recent experiments using the heating facility at the Arecibo Observatory in Puerto Rico have shown that the heater is capable of producing large-scale sheet-like irregularities through instability processes [Lee et al, 1998a] and depleted flux tubes corresponding to plasma bubbles [Lee et al, 1998b[Lee et al, , 1999. These results confirm the longstanding suspicion of some that heater effects need not remain confined locally and to small scales and support the idea that heating may affect the ducting of VLF emissions on nearby field lines by enhancing the coupling of wave energy into the plasma [Lee et al, 1992].…”

Section: Introductionmentioning

confidence: 99%

Interhemispheric propagation of VLF transmissions in the presence of ionospheric HF heating

Starks¹,

Lee²,

Jastrzębski³

2001

J. Geophys. Res.

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Abstract. Recent experiments carried out at the Arecibo Observatory in Puerto Rico and the magnetically conjugate location in Argentina suggest a connection between the prevalence and intensity of the interhemispheric propagation of VLF transmissions and HF heating of the ionosphere. During several nights of the study the O-mode CW heater appeared to enhance the coupling of VLF transmissions into the affected region of plasma. These signals presumably then entered plasmaspheric ducts more efficiently and led to conjugate measurements of relatively high amplitude. No such effects were seen with pulsed or X-mode heating. Short time resolution measurements of fading transmissions were marked by transit delays and amplitudes that remained nearly constant as the interhemispheric VLF signals diminished, consistent with the model of a plasmaspheric duct complemented by favorable plasma structures extending well into the F region but producing the majority of the total transit delay at plasmaspheric altitudes. It is also suggested that weak long-delay receptions often observed in these data are most probably prolongitudinal whistlers that are not ducted but which represent a potential contaminant in ducted VLF experiments of all types.

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Features of amplitude and Doppler frequency variation of ELF/VLF waves generated by “beat‐wave” HF heating at high latitudes

Tereshchenko

Шумилов

Касаткина

et al. 2014

Geophysical Research Letters

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Observations of extremely low frequency (ELF, 3-3000 Hz) radio waves generated by a "beat-wave" (BW) high frequency (~4.04-4.9 MHz) ionospheric heating are presented. ELF waves were registered with the ELF receiver located at Lovozero (68°N, 35°E), 660 km east from the European Incoherent Scatter Tromso heating facility (69. 6°N, 19.2°E). Frequency shifts between the generated beat-wave and received ELF waves were detected in all sessions. It is shown that the amplitudes of ELF waves depend on the auroral electrojet current strength. Our results showing a strong dependence of ELF signal intensities on the substorm development seem to support the conclusion that electrojet currents may affect the BW generation of ELF/VLF waves.

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Generation of large sheet‐like ionospheric plasma irregularities at Arecibo

Cited by 31 publications

References 17 publications

Experiments and theory on parametric instabilities excited in HF heating experiments at HAARP

Experiments and theory on parametric instabilities excited in HF heating experiments at HAARP

Interhemispheric propagation of VLF transmissions in the presence of ionospheric HF heating

Features of amplitude and Doppler frequency variation of ELF/VLF waves generated by “beat‐wave” HF heating at high latitudes

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