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A plasma vortex revisited: The importance of including ionospheric conductivity measurements

Kosch, Mike J. and Amm, O. and Scourfield, M.W.J. (2000) A plasma vortex revisited: The importance of including ionospheric conductivity measurements. Journal of Geophysical Research - Space Physics, 105 (A11). pp. 24889-24898. ISSN 0148-0227

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    Abstract

    In an earlier paper [Kosch et al., 1998], simultaneous all-sky TV imager and Scandinavian Twin Auroral Radar Experiment (STARE) observations of an ionospheric plasma vortex located poleward of an auroral arc were presented. The vortex is associated with a sudden brightening of the arc and corresponds to an ionospheric region of diverging horizontal electric fields, which is equivalent to a downward field-aligned current (FAC), i.e., the closure current for the upward current above the arc. This event has been revisited because of the subsequent availability of data from the Scandinavian Magnetometer Array. These data, combined with STARE electric fields, have been used to determine the real ionospheric conductance distribution throughout the field of view. As a result, a more realistic, quantitative picture of the current system associated with the arc is obtained than was possible in an earlier model based on an assumed constant conductance. In particular, a complete macroscopic electrodynamic description of a plasma vortex, composed of ionospheric conductances, true horizontal currents, and FACs, is obtained for the first time. It is shown that the plasma vortex corresponds to an area of decreased conductance, thus broadening the FAC distribution and reducing the current density compared to the earlier results. The study illustrates that horizontal conductance gradients should not be neglected when computing FACs.

    Item Type: Article
    Journal or Publication Title: Journal of Geophysical Research - Space Physics
    Additional Information: Copyright (2000) American Geophysical Union.
    Uncontrolled Keywords: DCS-publications-id ; art-115 ; DCS-publications-credits ; iono-fa ; DCS-publications-personnel-id ; 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: 6591
    Deposited By: ep_importer_dcs
    Deposited On: 21 Apr 2008 11:27
    Refereed?: Yes
    Published?: Published
    Last Modified: 26 Jul 2012 18:15
    Identification Number:
    URI: http://eprints.lancs.ac.uk/id/eprint/6591

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