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2000 Fiscal Year Final Research Report Summary

Theory and modeling of hydromagnetic instabilities

Research Project

Project/Area Number 09640529
Research Category

Grant-in-Aid for Scientific Research (C)

Allocation TypeSingle-year Grants
Section一般
Research Field Space and upper atmospheric physics
Research InstitutionThe University of Tokyo

Principal Investigator

MIURA Akira  Graduate School of Science, The University of Tokyo Research Associate, 大学院・理学系研究科, 助手 (20126171)

Project Period (FY) 1997 – 2000
KeywordsKelvin-Helmholtz instability / Hydromagnetic instability / vortex / self-organization / magnetopause / Ballooning instability / geomagnetic tail / substorm
Research Abstract

1. By two-dimensional hydrodynamic and hydromagnetic simulations of Kelvin-Helmholtz instability it has been shown that vortices excited by the instability merge in the nonlinear stage. In the hydromagnetic case a current eddy is associated with each vortex. The vortex pairing occurring in th nonlinear stage has been shown to be a self-organization process, wherein the total kinetic energy is conserved but the enstrophy decays rapidly to the minimum enstrophy state. The self-organization occurs owing to the inverse cascade of kinetic energy in the wave-number space.The momentum transport depends on the self-organization and the anomalous momentum transport in increases with a development of the self-organization. The observational fact that the magnetopause oscillation period increases with increasing distance in the downstream can be explained quantitatively by the simulation results showing the pairing of vortices in the nonlinear stage.
2. On the basis of the MHD energy principle and the perturbation analysis it has been shown that incompressible assumption is more valid for the ballooning instability when the manetosphere becomes more tail-like. This justifies an early linear analysis of the ballooning instability in the tail-like configuration based on incompressible assumption. This result suggests that the ballooning instability may be relevant to the onset of magnetospheric substorms, which occur when the magnetosphere becomes tail-like in the night-side.

  • Research Products

    (12 results)

All Other

All Publications (12 results)

  • [Publications] Miura,A.: "Compressible magnetohydrodynamic Kelvin-Helmholtz instability with vortex pairing in the Two-dimensional transverse configuration"Physics of Plasmas. 4.8. 2871-2885 (1997)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Miura,A.: "Self-organization in the two-dimensional Kelvin-Helmholtz instability"Physical Review Letters. 83.8. 1586-1589 (1999)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Miura,A.: "Self-organization in the two-dimensional magnetohydrodynamic transverse Kelvin-Helmholtz instability"Journal of Geophysical Research. 104.A1. 395-411 (1999)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Miura,A.: "A quantitative test of the self-organization hypothesis of the magnetopause Kelvin-Helmholtz instability as an inverse problem"Geophysical Research Letters. 26.3. 409-412 (1999)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Miura,A.: "Conditions for the validity of the incompressible assumption for the ballooning instability in the long-thin magnetospheric equilibrium"Journal of Geophysical Research. 105.A8. 18793-18806 (2000)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Miura,A.: "Ballooning instability as a mechanism of the near-Earth onset of substorms"Space Science Reviews. 95.Jan1/2. 387-398 (2001)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Miura, A.: "Compressible magnetohydrodynamic Kelvin-Helmholtz instability with vortex pairing in the two-dimensional transverse configuration"Phys.Plasmas. 4(8). 2871-2885 (1997)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Miura, A.: "Self-organization in the two-dimensional Kelvin-Helmholtz instability"Phys.Rev.Lett.. 83(8). 1586-1589 (1999)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Miura, A.: "Self-organization in the two-dimensional magnetohydrodynamic transverse Kelvin-Helmholtz instability"J.Geophys.Res.. 104(A1). 395-411 (1999)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Miura, A.: "A quantitative test of the self-organization hypothesis of the magnetopause Kelvin-Helmholtz instability as an inverse problem"Geophys.Res.Lett.. 26(3). 409-412 (1999)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Miura, A.: "Conditions for the validity of the incompressible assumption for the ballooning instability in the long-thin magnetospheric equilibrium"J.Geophys.Res.. 105(A8). 18793-18806 (2000)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Miura, A.: "Ballooning instability as a mechanism of the near-earth onset of substorms"Space Sci.Rev.. 95(January 1/2). 387-398 (2001)

    • Description
      「研究成果報告書概要(欧文)」より

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Published: 2002-03-26  

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