Japan Geoscience Union Meeting 2014

Presentation information

Print

International Session (Oral)

Symbol P (Space and Planetary Sciences) » P-EM Solar-Terrestrial Sciences, Space Electromagnetism & Space Environment

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

Wed. Apr 30, 2014 4:15 PM - 5:30 PM 213 (2F)

Convener:*Mitsuteru Sato(Department of Cosmoscience, Hokkaido University), Toru Adachi(Waseda Institute for Advanced Study, Waseda University), Tomoo Ushio(Information and communication engineering department, Osaka University), Yukihiro Takahashi(Department of Cosmosciences, Graduate School of Science, Hokkaido University), Chair:Mitsuteru Sato(Department of Cosmoscience, Hokkaido University), Kozo Yamashita(Dept.Electrical Engineering, Salesian Polytechnic.)

4:30 PM - 4:45 PM

★ [PEM07-09] Variations in the D-region ionosphere associated with lightning EMP using AVON and VLF/LF data in Japan

*Hiroyo OHYA1, Fuminori TSUCHIYA2, Kozo YAMASHITA3, Yukihiro TAKAHASHI4, Kazuo SHIOKAWA5, Yoshizumi MIYOSHI5 (1.Graduate School of Engineering, Chiba University, 2.Tohoku University, 3.Salesian Polytecnic, 4.Hokkaido University, 5.Solar-Terrestrial Environment Laboratory, Nagoya University)

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.