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Geophysical Research Letters

Global distribution of equatorial magnetosonic waves observed by THEMIS

Authors

  • Qianli Ma,

    Corresponding author
    1. Atmospheric and Oceanic Department, University of California, Los Angeles, Los Angeles, California, USA
    • Corresponding author: Q. Ma, Atmospheric and Oceanic Department, University of California, Los Angeles, Mathematical Sciences Building 7984, Los Angeles, California, 90095, USA. (qianlima@atmos.ucla.edu)

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  • Wen Li,

    1. Atmospheric and Oceanic Department, University of California, Los Angeles, Los Angeles, California, USA
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  • Richard M. Thorne,

    1. Atmospheric and Oceanic Department, University of California, Los Angeles, Los Angeles, California, USA
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  • Vassilis Angelopoulos

    1. Earth and Space Sciences Department, University of California, Los Angeles, Los Angeles, California, USA
    2. Institute of Geophysics and Planetary Physics, University of California, Los Angeles, Los Angeles, California, USA
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Abstract

[1] We investigate the wave magnetic field data from three THEMIS spacecraft over the recent 31 months to perform a statistical study of equatorial magnetosonic (MS) wave properties and spatial distribution. The THEMIS spacecraft provide good data coverage in the dominant MS wave region near the equator and at 2≤L≤8. Our global survey shows that strong amplitudes and high occurrence of MS waves are generally observed near the equator, outside the plasmapause, on the dawnside during geomagnetically disturbed periods. In addition, increase of geomagnetic activity shifts the MS wave distribution toward earlier magnetic local time. Strong MS waves generally have RMS wave amplitudes ∼50 pT and an occurrence rate ∼20% on the dawnside outside the plasmapause and could therefore have an important influence on both ring current ion and energetic electron dynamics in the Earth's radiation belts.

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