[M-IS13] Atmospheric electricity: Application of technology for reducing disaster risks

[MIS13-06] Multi-wavelength observation of a terrestrial gamma-ray flash with collision of two lightning leaders

*Yuuki Wada¹, Takeshi Morimoto², Ting Wu³, Daohong Wang ³, Hiroshi Kikuchi⁴, Yoshitaka Nakamura⁵, Eiichi Yoshikawa⁶, Tomoo Ushio¹, harufumi Tsuchiya⁷ (1.Osaka University, 2.Kindai University, 3.Gifu University, 4.University of Electro-Communications, 5.KCCT, 6.Colorado State University, 7.JAEA)

Keywords:terrestrial gamma-ray flash, lightning flash, high-energy atmospheric physics

Terrestrial Gamma-ray Flash (TGF) is a phenomenon where electrons are accelerated and amplified to relativistic energies synchronously with the occurrence of lightning discharges, generating a large amount of gamma rays. However, it is not clear how lightning discharges accelerate and amplify electrons in the dense atmosphere. We have conducted focused observations targeting winter lightning strikes on a television broadcasting tower in Kanazawa City, Ishikawa Prefecture, and successfully detected a TGF on January 30, 2023. The TGF occurred 30 μs ahead of the return stroke, and a signature of a downward negative leader is observed through radio observations, while a upward positive leader extending from the tower was also captured by an optical camera. Based on the observation, we consider that the TGF occurred when two leaders approached or collided.