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First tomographic estimate of volume distribution of HF-pump enhanced airglow emission

Gustavsson, B. and Sergienko, T. and Rietveld, M. T. and Honary, Farideh and Steen, A. A. and Brändström, B. U. E. and Leyser, T. B. and Aruliah, A. L. and Aso, T. and Ejiri, M. and Marple, S. (2001) First tomographic estimate of volume distribution of HF-pump enhanced airglow emission. Journal of Geophysical Research, 106 (A12). pp. 29105-29123. ISSN 0148-0227

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    Abstract

    This report presents the first estimates of the three-dimensional volume emission rate of enhanced O(1D) 6300 Å airglow caused by HF radio wave pumping in the ionosphere. Images of the excitation show how the initially speckled spatial structure of excitation changes to a simpler shape with a smaller region that contains most of the excitation. A region of enhanced airglow was imaged by three stations in the Auroral Large Imaging System (ALIS) in northern Scandinavia. These images allowed for a tomography-like inversion of the volume emission of the airglow. The altitude of maximum emission was found to be around 235 ± 5 km with typical horizontal and vertical scale sizes of 20 km. The shape of the O(1D) excitation rate varied from flatish to elongated along the magnetic field. The altitude of maximum emission is found to be approximately 10 km below the altitude of the enhanced ion line and 15 km above the altitude of maximum electron temperature. Comparisons of the measured altitude and temporal variations of the 6300 Å emission with modelled emission caused by O(1D) excitation from the high energy tail of a Maxwellian electron distribution show significant deviations. The 6300 Å emission from excitation of the high energy tail is about a factor of 4 too large compared with what is observed. This shows that the source of O(1D) excitation is electrons from a “sub-thermal” distribution function, i.e. the electron distribution is Maxwellian at low energies and at energies above 1.96 eV there is a depletion.

    Item Type: Article
    Journal or Publication Title: Journal of Geophysical Research
    Additional Information: Copyright (2001) American Geophysical Union.
    Uncontrolled Keywords: heating DCS-publications-id ; art-230 ; DCS-publications-credits ; iono ; DCS-publications-personnel-id ; 193 ; 5 ; 4
    Subjects: T Technology > T Technology (General)
    Departments: Faculty of Science and Technology > School of Computing & Communications
    Faculty of Science and Technology > Engineering
    Faculty of Science and Technology > Physics
    ID Code: 6599
    Deposited By: ep_importer_dcs
    Deposited On: 21 Apr 2008 11:39
    Refereed?: Yes
    Published?: Published
    Last Modified: 09 Apr 2014 22:09
    Identification Number:
    URI: http://eprints.lancs.ac.uk/id/eprint/6599

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