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2000 Fiscal Year Final Research Report Summary

Processes of optical and radio emissions in the upper atmosphere induced by cloud to ground discharge

Research Project

Project/Area Number 10304036
Research Category

Grant-in-Aid for Scientific Research (A).

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

Principal Investigator

FUKUNISHI Hiroshi  Tohoku University, Graduate School of Science, Professor, 大学院・理学研究科, 教授 (90099937)

Co-Investigator(Kenkyū-buntansha) MURATA Isao  Graduate School of Science, Tohoku University, Research Associate, 大学院・理学研究科, 助手 (00291245)
TAKAHASHI Yukihiro  Graduate School of Science, Tohoku University, Lecturer, 大学院・理学研究科, 講師 (50236329)
WATANABE Shigeto  Hokkaido University, Graduate School of Science, Professor, 大学院・理学研究科, 教授 (90271577)
NAGANO Isamu  Kanazawa University, Graduate School of Technology, Professor, 工学部, 教授 (50019775)
SAKANOI Takeshi  Graduate School of Science, Tohoku University, Research Associate, 大学院・理学研究科, 助手 (80271857)
Project Period (FY) 1998 – 2000
Keywordssprites / elves / lightning / mesosphere / thermosphere / Hokuriku / winter / spectrum
Research Abstract

In 1990 a discharge phenomenon from the stratosphere to the ionosphere was found during the tcst observation of a low-light TV camera employed by University of Minnesota. Since this discovery a lot of observations from ground, aircraft and space shuttle have been carried out. It is found that these kinds of optical emissions in the stratosphere, mesosphere and lower ionosphere, now called sprites and elves, are induced by an intense cloud to ground discharge and that the phenomena are accompanied by strong radio and gamma ray emissions. Optical emissions of sprites and elves are considered to be caused by an excitation via collision processes between atmospheric molecules/atoms and electrons that are energized by quasi-static electric field or electromagnetic impulse generated by a cloud to ground discharge. We estimated the electron energies based on the spectral observations with high-speed photometers. It is found that electron temperature has a peak of 3-25 eV for carrot-like sprites and 2-14 eV for column type sprites at the onset of the optical emission. In a body of carrot-like sprites the electron temperature tends to increase as altitude decreases with a local peak of 12-20 eV at an altitude of 〜80 km that corresponds to gap between hair and head region of sprites. On the other hand, it is confirmed that elves are caused by a negative cloud to ground discharge as well as a positive one. Electron energy of elves was found to reach up to 40 eV, which implies a strong ionization in the lower ionosphere. We conducted optical observation in Japan and showed the occurrences of sprites and elves in winter for the first time in the world. We also analyzed the "sprite halo" which appears as a diffuse fashion with a disk-like shape and revealed its time-space structure of luminous intensity and electron temperature.

  • Research Products

    (10 results)

All Other

All Publications (10 results)

  • [Publications] Takahashi,Y.,et al.: "Energy distributions of electrons exciting sprites and elves inferred from the fast array photometer observations"EOS Trans.AGU. 79. F175 (1998)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] H.Fukunishi et al.: "Occurrences of sprites and elves above the Sea of Japan near Hokuriku in winter"EOS Transactions. 80. F217 (1999)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] A.Uchida et al.: "Energies of electrons for inducing elves estimated from N2 1P/2P ratio observation"EOS Transactions. 80. F225 (1999)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Takahashi,Y.,et al.: "Temporal and spatial variations in the intensity ratio of N2 1st and 2nd positive bands in sprites"Adv.Space Res.. 26. 1205-1208 (2000)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Sato,M.,et al.: "ELF Transients Observed at Syowa Station,Antarctica during the STEPS Campaign"EOS Trans.AGU. 80. F134 (2000)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Takahashi, Y., et al: "Energy distributions of electrons exciting sprites and elves inferred from the fast array photometer observations"EOS Trans.AGU.. 79. F175 (1998)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Fukunishi, H., et al: "Occurrences of Sprites and Elves above the Sea of Japan near Hokuriku in winter"EOS Trans.AGU.. 80. F217 (1999)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Uchida, A., et al: "Energies of electrons for inducing elves estimated from N2 1P/2P ratio observation"EOS Trans.AGU.. 80. F225 (1999)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Takahashi, Y., et al: "Temporal and spatial variations in the intensity ratio of N 1st and 2nd positive bands in sprites"Adv.Space Res.. 26. 1,205-1,208 (2000)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Sato, M., et al: "ELF Transients Observed at Syowa Station, Antarctica during the STEPS Campaign"EOS Trans.AGU.. 80. F134 (2000)

    • 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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