Schumann Resonance for monitoring of ionosphere

2022 Fiscal Year Final Research Report

• Project/Area Number: 19K03956
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 17010:Space and planetary sciences-related
• Research Institution: Kagoshima National College of Technology
• Principal Investigator: Ikeda Akihiro 鹿児島工業高等専門学校, 一般教育科, 准教授 (90582833)
• Co-Investigator(Kenkyū-buntansha): 吉川 顕正 九州大学, 理学研究院, 教授 (70284479) ; 藤本 晶子 九州工業大学, 大学院情報工学研究院, 准教授 (40578803)
• Project Period (FY): 2019-04-01 – 2023-03-31
• Keywords: シューマン共鳴 / 太陽活動 / フレア / SPE / 電離圏

Outline of Final Research Achievements

We examined Schumann Resonance (SR) measured by an induction magnetometer at Kuju, Japan. The periodicity of SR parameters is dominant at about 360 and 180 days. The 27-days period, which corresponds to the solar rotational period, also can be seen. The daily variation of SR amplitudes corresponded with the thunderstorm activity in Africa, Asia, North America, and South America. We further found the SR frequency well correlated with EUV flux for long period.
Variations of SR frequency often associated with solar flares. Since X-ray and EUV of flares enhance the ionization of Earth's ionosphere, the variation of the SR frequency seems to reflect the electron density in the ionospheric D-region. For SPEs (solar proton events), the variation of the SR frequency in eastward component corresponded with enhancement of the Proton flux. We conclude that SR reflects conditions of the lower ionosphere during the intense solar activity.

Free Research Field

超高層大気物理学

Academic Significance and Societal Importance of the Research Achievements

フレアや太陽プロトンイベント（SPE）といった、宇宙災害を引き起こす現象に伴うシューマン共鳴（SR）の変動を明らかにできたことは学術的意義を持つ。また、下部電離圏の変動は衛星などによる観測が困難な領域であるため、SRから下部電離圏の密度変化を推定できたことは、宇宙天気という観点からも意義がある事である。さらにSRは地球の気候変化、地震との対応も確認されており、本研究で解明したSRの特性は、それら異分野の学術研究にも利用可能という発展性を持つ。