Study of auroral current system using satellite observations and a magnetic inversion method

• Project/Area Number: 23540524
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Space and upper atmospheric physics
• Research Institution: Nagoya University
• Principal Investigator: IEDA Akimasa 名古屋大学, 太陽地球環境研究所, 助教 (70362209)
• Project Period (FY): 2011-04-28 – 2015-03-31
• Project Status: Completed (Fiscal Year 2014)
• Budget Amount: ¥5,070,000 (Direct Cost: ¥3,900,000、Indirect Cost: ¥1,170,000); Fiscal Year 2014: ¥780,000 (Direct Cost: ¥600,000、Indirect Cost: ¥180,000); Fiscal Year 2013: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000); Fiscal Year 2012: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000); Fiscal Year 2011: ¥1,690,000 (Direct Cost: ¥1,300,000、Indirect Cost: ¥390,000)
• Keywords: 電離層電気伝導度 / Chapaman理論 / 電離圏 / 太陽天頂角 / 太陽放射 / 太陽EUV / 超高層物理学 / 宇宙科学 / 国際情報交流（米国）

Outline of Final Research Achievements

The solar zenith angle (SZA) dependence of the conductance is studied and a simple theoretical form for the conductance is developed, using the peak plasma production height. The daytime electric conductance is associated with plasma created by solar extreme ultraviolet radiation incident on the neutral atmosphere of the Earth. However, it has been uncertain whether previous conductance models are consistent with the ideal Chapman theory for such plasma productions. We found that the SZA dependence of the conductance is consistent with the Chapman theory after simple modifications. An additional consideration is necessary for the Hall conductance, which decreases with increasing SZA more rapidly than the Pedersen conductance. This rapid decrease is presumably caused by a thinning of the Hall conductivity layer from noon toward nighttime. We expressed this thinning in terms of the peak production height in the Chapman theory.

Research Products

• [Journal Article] Approximate forms of daytime ionospheric conductance (2014)
  • Author(s): Ieda, A., S. Oyama, H. Vanhamäki, R. Fujii, A. Nakamizo, O. Amm, T. Hori, M. Takeda, G. Ueno, A. Yoshikawa, R. J. Redmon, W. F. Denig, Y. Kamide, and N. Nishitani
  • Journal Title: Journal of Geophysical Research Volume: 119 Issue: 12 Pages: 10397-10415
  • DOI: 10.1002/2014ja020665
  • Peer Reviewed / Acknowledgement Compliant
• [Journal Article] Statistical visualization of the Earth’s magnetotail and the implied mechanism of substorm triggering based on superposed-epoch analysis of THEMIS data (2014)
  • Author(s): Machida, S., Y. Miyashita, A. Ieda, M. Nosé, V. Angelopoulos, and J. P. McFadden
  • Journal Title: Annales Geophysicae Volume: 32 Issue: 2 Pages: 99-111
  • DOI: 10.5194/angeo-32-99-2014
  • Peer Reviewed
• [Presentation] 昼間電離圏の電気伝導度比 (2014)
  • Author(s): 家田章正, 大山伸一郎, 藤井良一, 中溝葵, 堀智昭, 吉川顕正, 西谷望
  • Organizer: 日本地球惑星科学連合2014年大会
  • Place of Presentation: 横浜
  • Year and Date: 2014-04-29
• [Presentation] 昼間電離圏の電気伝導度比 (2013)
  • Author(s): 家田章正、大山伸一郎、藤井良一、中溝葵
  • Organizer: 地球電磁気・地球惑星圏学会
  • Place of Presentation: 高知
• [Presentation] オーロラ爆発直前の降下粒子
  • Author(s): 家田章正、堀智昭、関華奈子、宮下幸長、藤本正樹、西村幸敏、R. Strangeway、町田忍、G. K. Parks, J. P. McFadden
  • Organizer: 地球電磁気・地球惑星圏学会
  • Place of Presentation: 札幌
• [Presentation] オーロラ爆発開始時における降下電子の2衛星観測
  • Author(s): 家田章正、藤本正樹、堀智昭、西村幸敏、関華奈子、町田忍、宮下幸長
  • Organizer: 地球電磁気・地球惑星圏学会
  • Place of Presentation: 神戸
• [Remarks] 実証型ジオスペース環境モデリングシステム
  • URL: http://st4a.stelab.nagoya-u.ac.jp/gemsis/