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Spatiotemporal evolution of radio wave pump-induced ionospheric phenomena near the fourth electron gyroharmonic

Ashrafi, M. and Kosch, Mike J. and Kaila, K. and Isham, B. (2007) Spatiotemporal evolution of radio wave pump-induced ionospheric phenomena near the fourth electron gyroharmonic. Journal of Geophysical Research, 112 (A5). A05314. ISSN 0148-0227

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    Abstract

    On 12 November 2001, the European Incoherent Scatter (EISCAT) high-frequency (HF) radio wave transmitter facility, operating in O-mode at 5.423 MHz with 550 MW effective radiated power, produced artificial optical rings which appeared immediately at transmitter turn-on and collapsed into blobs after ∼60 s while descending in altitude. A similar descent in altitude was observed in the EISCAT ultra high frequency (UHF) ion line enhancements. Likewise, the stimulated electromagnetic emission (SEE) spectra changed as the pump frequency approached the fourth electron gyroharmonic due to pump-induced variations in electron concentration. Optical recordings were made from Skibotn at 630.0 and 557.7 nm and from Ramfjord in white light. The altitude of the initial optical ring and steady state blob has been estimated by triangulation. The evolution in altitude of the optical emissions, ion line enhancements, and SEE spectra all show a similar morphology but are generally not at exactly the same height. Typically, the optical height is close to and a few kilometers below that of the radar backscatter but sometimes above it, both of which are above the SEE generation altitude. There is evidence that upper hybrid (UH) waves, which propagate perpendicular to the magnetic field line, and Langmuir (L) waves, which propagate parallel to the magnetic field line, act simultaneously to accelerate electrons even in the steady state.

    Item Type: Article
    Journal or Publication Title: Journal of Geophysical Research
    Additional Information: Copyright (2007) American Geophysical Union. Further reproduction or electronic distribution is not permitted
    Uncontrolled Keywords: eiscat ; heating ; see DCS-publications-id ; art-856 ; DCS-publications-credits ; dasi ; iono-fa ; DCS-publications-personnel-id ; 66 ; 7
    Subjects: T Technology > T Technology (General)
    Departments: Faculty of Science and Technology > School of Computing & Communications
    Faculty of Science and Technology > Physics
    ID Code: 6712
    Deposited By: ep_importer_dcs
    Deposited On: 21 Apr 2008 12:26
    Refereed?: Yes
    Published?: Published
    Last Modified: 09 Apr 2014 22:12
    Identification Number:
    URI: http://eprints.lancs.ac.uk/id/eprint/6712

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