[P-EM13] Dynamics of the Inner Magnetospheric System

[PEM13-13] あらせ衛星およびWWLLNデータを用いた放射線帯電子と地上の雷活動の長期的関連

*宇井 瞭介¹、Martinez-Calderon Claudia¹、塩川 和夫¹、篠原 育²、三好 由純¹、笠原 慧³、桂華 邦裕³、横田 勝一郎⁴、堀 智昭¹、三谷 烈史²、高島 健²、Wang Shiang-Yu⁵、Kazama Yoichi⁵、Jun Chae-Woo¹、Bortnik Jacob⁶、Rodger Craig⁷ (1.名古屋大学 宇宙地球環境研究所、2.宇宙航空研究開発機構 宇宙科学研究所、3.東京大学 大学院理学系研究科 地球惑星科学専攻、4.大阪大学 大学院理学研究科 宇宙地球科学専攻、5.Academia Sinica Institute of Astronomy and Astrophysics、6.University of California Los Angeles、7.Department of Physics, University of Otago)

キーワード：磁気圏、放射線帯、電子降りこみ、ホイッスラー、雷放電

Lightning discharges occurring in Earth's atmosphere emit electromagnetic waves across a wide range of frequencies spanning multiple bands. Among these, a portion of Very Low Frequency (VLF) waves propagate through the ionosphere in the whistler mode, usually following Earth's magnetic field lines and reaching the radiation belts. These whistler waves interact with electrons in the radiation belts, leading to electron precipitation and subsequent electron loss. One-to-one correlations between lightning activity and electron precipitation using both simulations and observational data have been investigated, however, the long-term impact of lightning-induced whistler waves on the total radiation belts trapped population remains unclear. To address this, Martinez-Calderon et al. 2020 analyzed lightning activity data from the World Wide Lightning Location Network (WWLLN) and trapped electron fluxes from the Van Allen Probes. However, analyses over timescales of a few days to a year unexpectedly revealed only a moderate positive correlation, not as strong as expected from theoretical predictions.
This study re-evaluates the long-term effects of lightning activity on radiation belt electrons using electron flux data from the Arase satellite's Low-Energy Particle Experiments - Electron Analyzer (LEP-e), Medium-Energy Particle Experiments - Electron Analyzer (MEP-e), and High-Energy Electron Experiments (HEP-L) instruments, in conjunction with global lightning activity data from WWLLN for the year 2018. By conducting a detailed comparative analysis across different electron energies and L-shells, we will validate or dispute previous results and quantitatively assess the long-term influence of lightning activity on radiation belt electrons. We will particularly consider the influence of AE index compared to lightning, and other parameters of interest (hemisphere of lightning stroke, estimated energy, seasonal and day/night dependence).