[P-EM13] Dynamics of the Inner Magnetospheric System

[PEM13-13] Long Term Correlation between Lightning Activity and Trapped Radiation Belt Electrons from WWLLN and ERG comparisons

*Ryosuke Ui¹, Claudia Martinez-Calderon¹, Kazuo Shiokawa¹, Iku Shinohara², Yoshizumi Miyoshi¹, Satoshi Kasahara³, Kunihiro Keika³, Shoichiro Yokota⁴, Tomoaki Hori¹, Takefumi Mitani², Takeshi Takashima², Shiang-Yu Wang⁵, Yoichi Kazama⁵, Chae-Woo Jun¹, Jacob Bortnik⁶, Craig J Rodger⁷ (1.Institute for Space-Earth Environmental Research, Nagoya University, 2.Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3.Department of Earth and Planetary Science, School of Science, University of Tokyo, 4.Department of Earth and Space Science, Graduate School of Science, Osaka University, 5.Academia Sinica Institute of Astronomy and Astrophysics, 6.University of California Los Angeles, 7.Department of Physics, University of Otago)

Keywords:Magnetosphere, Radiation Belt, Electron Precipitation, Whistler, Lightning Discharge

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).