[P-EM07_30PM2] Lightning and TLEs and their effects on the lower and middle atmosphere

★ [PEM07-09] AVONおよび日本のVLF/LFデータを用いた雷EMPに関連したD領域電離圏変動

*大矢 浩代¹、土屋 史紀²、山下 幸三³、高橋 幸弘⁴、塩川 和夫⁵、三好 由純⁵ (1.千葉大学大学院工学研究科、2.東北大学、3.サレジオ工業高等専門学校、4.北海道大学、5.名古屋大学太陽地球環境研究所)

It is known that the electromagnetic pulse (EMP) originated from cloud-to-ground and inter-cloud lightning discharges can couple directly into the D-region ionosphere. The conductivity in the D-region changes due to the EMP. When VLF/LF waves propagate under the disturbed D-region, the amplitude and phase or the reflection height of the VLF/LF waves varies largely. For example, 'early VLF events' show large variations in amplitude and phase and are caused by the coupling between the D-region and lightning. Early/fast events, early/slow events, and long recovery events are included in the term of 'early VLF events'. The descent (rise) of VLF/LF reflection height corresponds to increase (decrease) in electron density in the D-region. We have conducted Asia VLF observation network (AVON) in South-East Asia: Taiwan, Thailand, Indonesia, Philippines, and Vietnam since 2007. The observations consist of 5 stations in Taiwan, Thailand, Indonesia, Philippines, and Vietnam. The aim of the AVON is to monitor the lower ionosphere and lightning in South-East Asia. We observe North-South and East-West wideband magnetic components with loop antennas, a vertical broadband electric component with a dipole antenna, and amplitude and phase of narrowband LF transmitter signals with a monopole antenna. We investigate the VLF/LF perturbations associated with the lightning discharges using both the AVON data and the VLF/LF data observed in Japan. In the presentation, we show the results of coupling between the D-region and lightning using AVON data.