Height-integrated conductivity in auroral substorms - 2. Modeling

Jesper Wittendorff Gjerløv, R.A. Hoffman

    Research output: Contribution to journalJournal articleResearchpeer-review

    Abstract

    Calculations of height-integrated conductivity from 31 individual Dynamics Explorer (DE 2) substorm crossings presented by Gjerloev and Hoffman [this issue] are used to compile empirical models of the height-integrated Pedersen and Hall conductivities (conductances) in a bulge-type auroral substorm. Global auroral images obtained by Dynamics Explorer 1 (DE 1) were used to select substorms displaying a typical bulge-type emission pattern and each individual DE 2 pass was positioned with respect to key features in the observed emission pattern. The conductances were calculated for each DE 2 pass using electron precipitation data and a monoenergetic conductance model. All passes were divided into six different sectors, and average conductance profiles were carefully deduced for each of these sectors. Using a simple boxcar filter, smoothed average sector passes were calculated and from linear interpolation between these, two-dimensional conductance models were compiled. The characteristics of our models are (1) the Hall conductance maximizes in the high-latitude part of the surge at 48 mho with a Hall to Pedersen ratio of 2.4; (2) two channels of enhanced conductance are overlapping in local time near midnight and are fairly separated in latitude; (3) the conductance has a sharp gradient at the high-latitude boundary in the premidnight sector while in the postmidnight sector a broad region of low conductance stretches up to 10 degrees invariant latitude poleward of the local peak; and finally, (4) the enhanced conductance region displays a characteristic broadening toward dawn primarily owing to a poleward shift of the high-latitude boundary.
    Original languageEnglish
    JournalJournal of Geophysical Research-space Physics
    Volume105
    Issue numberA1
    Pages (from-to)227-235
    ISSN2169-9380
    Publication statusPublished - 2000

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