The Excitation of Shear Alfven Wave and the Associated Modulation of Compressional Wave in the Inner Magnetosphere

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Two basic but novel equations directly describing the generation of shear Alfvén and compressional waves in the inner magnetosphere filled with a cold magnetized plasma are derived. The shear Alfvéen wave is characterized by the field-aligned current and the compressional wave by the compressional component of the magnetic field. Such a generation arises from the effects of inhomogeneous Alfvén speed and curvilinear field line. Around the magnetic equator, if the Alfvén speed is inversely proportional to a power of the geocentric distance, these effects have magnitudes of the same order and their signs are identical. Considered in the present study is a situation that the earthward propagating compressional wave is launched from a large scale oscillating current wedge centered at midnight and symmetric about the magnetic equator. Then, it is found that the field-aligned current excited around the equator by the compressional wave has opposite senses in direction in the northern and southern hemispheres, in the pre- and post-midnight sectors as well as just inside the plasmapause and in its surrounding regions. As a result of the excitation of shear Alfvén wave, two types of oscillations appear on a field line: One is a forced oscillation and the other is an eigenoscillation. Although a modulation of the compressional wave may be caused locally (or microscopically) around the equator by the eigenoscillation of field line, the modulation can be globally (or macroscopically) neglected. So far as the propagation along the source longitude (source-earth line) around the equator is concerned, the coupling between compressional and shear Alfvén waves can be almost neglected and so one-dimensional response of the inner magnetosphere around the equator plays a significant role in the compressional oscillation.

収録刊行物

  • Journal of geomagnetism and geoelectricity  

    Journal of geomagnetism and geoelectricity 48(11), 1451-1459, 1996-11 

    Society of Geomagnetism and Earth, Planetary and Space Sciences

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各種コード

  • NII論文ID(NAID)
    10002404317
  • NII書誌ID(NCID)
    AA00698879
  • 本文言語コード
    ENG
  • 資料種別
    ART
  • ISSN
    00221392
  • NDL 記事登録ID
    4109553
  • NDL 雑誌分類
    ZM41(科学技術--地球科学)
  • NDL 請求記号
    Z53-A457
  • データ提供元
    CJP書誌  NDL  J-STAGE 
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