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A study of magnetotail dynamics during substorms using high-time resolution data

Research Project

Project/Area Number 13640449
Research Category

Grant-in-Aid for Scientific Research (C)

Allocation TypeSingle-year Grants
Section一般
Research Field Space and upper atmospheric physics
Research InstitutionNagoya University

Principal Investigator

SHIOKAWA Kazuo  Nagoya University, Solar-Terrestrial Environment Laboratory, Associate Professor, 太陽地球環境研究所, 助教授 (80226092)

Project Period (FY) 2001 – 2003
Project Status Completed (Fiscal Year 2003)
Budget Amount *help
¥2,100,000 (Direct Cost: ¥2,100,000)
Fiscal Year 2003: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 2002: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 2001: ¥900,000 (Direct Cost: ¥900,000)
Keywordsmagnetosphere / substorm / magnetic perturbation / inner magnetosphere / neutral sheet / magnetic reconnection
Research Abstract

We have investigated various characteristics of magnetic and plasma fluctuations for 21 events of substorm-associated near-Earth dipolarization at Xgsm=-8 --11 Re and |Ygsm|<5 Re, using high-time-resolution data for the magnetic field (1/16 s), plasma moment (12 s), and electric field (3 s) measured by the GEOTAIL satellite in 1995-2000. The dipolarizations are always accompanied by intense fluctuations of the magnetic field. The amplitude of the fluctuations is larger for smaller B (closer to the cross-tail current sheet). We found several events in which the magnetic field elevation angles decreased rapidly prior to the dipolarization (explosive growth phase (EGP)-like features). The magnetic fluctuations are not sinusoidal curves but are spikes of a sudden decrease and increase with a time scale of seconds. In quite a few cases, the fluctuations are accompanied by Earthward convective plasma flow. The spectral shape of the fluctuations has a steeper slope (f^-2.7) at 1.0-0.2 Hz than at 0.01-0.2 Hz (f^-2.0). From the correlation between plasma velocity and magnetic field fluctuations, we estimate the parallel scale sizes of waves with periods of 60 s and 15 s to be about 10 Re and 5 Re, respectively. For the 60-s waves, the magnetic and plasma pressure variations are clearly anti-phase. The total pressure tends to decrease gradually before the dipolarization and increase during and after the dipolarization.

Report

(4 results)
  • 2003 Annual Research Report   Final Research Report Summary
  • 2002 Annual Research Report
  • 2001 Annual Research Report
  • Research Products

    (8 results)

All Other

All Publications (8 results)

  • [Publications] Shiokawa, K.: "Substorm-associated magnetic field fluctuations around X=-10Re"Proceeding of the 6th International Conference on Substorms. 318-325 (2002)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2003 Final Research Report Summary
  • [Publications] Shiokawa, K.: "Multiple auroral brightenings and associated Pi 2 pulsations"Geophysical Research Letters. 29(No.11). 2001GL014583 (2002)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2003 Final Research Report Summary
  • [Publications] Shiokawa, K.: "Bi-directional electrons in the near-Earth plasma sheet"Annales Geophysicae. 21. 1497-1507 (2003)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2003 Final Research Report Summary
  • [Publications] Shiokawa, K., I.Shinohara, T.Mukai, H.Hayakawa: "Substorm-associated magnetic field fluctuations around X=-10 Re"Proceeding of the 6th International Conference on Substorms. 318-325 (2002)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2003 Final Research Report Summary
  • [Publications] Shiokawa, K., K.Yumoto, J.V.Olson: "Multiple auroral brightenings and associated Pi 2 pulsations"Geophys.Res.Lett.. 29,No.11. doi:10.1029/2001GL014583 (2002)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2003 Final Research Report Summary
  • [Publications] Shiokawa, K., W.Baumjohann, G.Paschmann: "Bi-directional electrons in the near-Earth plasma sheet"Ann.Geophys.. 21. 1497-1507 (2003)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2003 Final Research Report Summary
  • [Publications] Shiokawa, K.: "Bi-directional electrons in the near-Earth plasma sheet"Annales Geophysicae. 21. 1497-1507 (2003)

    • Related Report
      2003 Annual Research Report
  • [Publications] Shiokawa, K.: "Substorm-associated magnetic field fluctuations around X=-10Re"Proceeding of the 6th International Conference on Substorms. 318-325 (2002)

    • Related Report
      2002 Annual Research Report

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Published: 2001-04-01   Modified: 2016-04-21  

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