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Geophysical Research Letters

Direct auroral precipitation from the magnetotail during substorms

Authors

  • Maha Ashour-Abdalla,

    Corresponding author
    1. Institute of Geophysics and Planetary Physics, UCLA, Los Angeles, California, USA
    2. Department of Physics and Astronomy, UCLA, Los Angeles, California, USA
    • Corresponding author: M. Ashour-Abdalla, Institute of Geophysics and Planetary Physics, UCLA, 405 Hilgard Ave., 3860 Slichter Hall, Los Angeles, CA 90095-1567, USA. (mabdalla@igpp.ucla.edu)

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  • David Schriver,

    1. Institute of Geophysics and Planetary Physics, UCLA, Los Angeles, California, USA
    2. Department of Physics and Astronomy, UCLA, Los Angeles, California, USA
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  • Mostafa El Alaoui,

    1. Institute of Geophysics and Planetary Physics, UCLA, Los Angeles, California, USA
    2. Department of Physics and Astronomy, UCLA, Los Angeles, California, USA
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  • Robert Richard,

    1. Institute of Geophysics and Planetary Physics, UCLA, Los Angeles, California, USA
    2. Department of Physics and Astronomy, UCLA, Los Angeles, California, USA
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  • Raymond Walker,

    1. Institute of Geophysics and Planetary Physics, UCLA, Los Angeles, California, USA
    2. Department of Earth and Space Sciences, UCLA, Los Angeles, California, USA
    3. National Science Foundation, Arlington, Virginia, USA
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  • Melvyn L. Goldstein,

    1. Heliospheric Physics Laboratory, NASA Goddard Space Flight Center, Greenbelt, Maryland, USA
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  • Eric Donovan,

    1. Department of Physics and Astronomy, University of Calgary, Calgary, Alberta, Canada
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  • Meng Zhou

    1. Institute of Space Science and Technology, Nanchang University, Nanchang, China
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Abstract

[1] In this study, we examine the causes of electron precipitation during a substorm on 15 February 2008 that lead to auroral brightening. We use global kinetic simulations along with spacecraft and ground-based data. We find ~keV electrons in the region modeled in the simulation precipitate into the premidnight sector at latitudes between 71° and 75° due to two distinct physical processes: (1) higher latitude precipitation due to electrons that undergo relatively rapid non-adiabatic pitch angle scattering into the loss cone just earthward of a reconnection region, and (2) lower latitude precipitation due to electrons that are more gradually accelerated primarily parallel to the geomagnetic field by Fermi acceleration. These latter electrons enter the loss cone much closer to Earth at ~−15 to −10 RE. The electron precipitation due to the combination of these two mechanisms coincides spatially with observed auroral brightening during the disturbed event.

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