Optical and Ionospheric Phenomena at EISCAT under continuous X-mode HF pumping

Blagoveshchenskaya, N. F. and Borisova, T. D. and Kosch, Michael and Sergienko, T. and Brandstrom, Urban and Yeoman, T. K. and Haggstrom, Ingemar (2014) Optical and Ionospheric Phenomena at EISCAT under continuous X-mode HF pumping. Journal of Geophysical Research, 119 (12). pp. 10483-10498. ISSN 0148-0227

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We present experimental results from multiinstrument observations in the high-latitude ionospheric F2 layer at the EISCAT (European Incoherent Scatter Scientific Association) heating facility. The results come from a set of experiments, when an X-polarized HF pump wave at high heater frequencies (fH > 6.0 MHz) was injected into the F region of the ionosphere toward the magnetic zenith. Experiments were carried out under quiet magnetic conditions with an effective radiated power of 458–548 MW. HF pumping was produced at different heater frequencies, away from electron gyroharmonic frequencies, and different durations of heater pulses. We show the first experimental evidence of the excitation of artificial optical emissions at red (630 nm) and green (557.7 nm) lines in the high-latitude ionospheric F2 layer induced by an X-polarized HF pump wave. Intensities at red and green lines varied in the range 110–950 R and 50–350 R, respectively, with a ratio of green to red line of 0.35–0.5. The results of optical observations are compared with behaviors of the HF-enhanced ion and plasma lines from EISCAT UHF incoherent scatter radar data and small-scale field-aligned artificial irregularities from Cooperative UK Twin Located Auroral Sounding System observations. It was found that the X-mode radio-induced optical emissions coexisted with HF-enhanced ion and plasma lines and strong artificial field-aligned irregularities throughout the whole heater pulse. It is indicative that parametric decay or oscillating two-stream instabilities were not quenched by fully established small-scale field-aligned artificial irregularities excited by an X-mode HF pump wave.

Item Type:
Journal Article
Journal or Publication Title:
Journal of Geophysical Research
Additional Information:
Copyright 2014 American Geophysical Union.
Uncontrolled Keywords:
?? active experimentsplasma waves and instabilitiesionospheric irregularitiesearth and planetary sciences (miscellaneous)geophysicsatmospheric sciencespace and planetary science ??
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Deposited On:
23 Dec 2014 13:24
Last Modified:
08 Jul 2024 23:44