日本地球惑星科学連合2019年大会

講演情報

[E] ポスター発表

セッション記号 P (宇宙惑星科学) » P-EM 太陽地球系科学・宇宙電磁気学・宇宙環境

[P-EM09] Vertical coupling in the atmosphere and Ionosphere

2019年5月29日(水) 17:15 〜 18:30 ポスター会場 (幕張メッセ国際展示場 8ホール)

コンビーナ:Liu Huixin(九州大学理学研究院地球惑星科学専攻 九州大学宙空環境研究センター)、Chang Loren(Institute of Space Science, National Central University)、大塚 雄一(名古屋大学宇宙地球環境研究所)

[PEM09-P10] Sub-ionospheric effects of volcano eruptions using VLF/LF standard radio waves

*丸山 慶1大矢 浩代1土屋 史紀2野崎 憲朗5山下 幸三3高橋 幸弘4中田 裕之1鷹野 敏明1 (1.千葉大学、2.東北大学、3.足利大学、4.北海道大学、5.情報通信研究機構)

Several studies for the F-region ionosphere associated with volcano eruptions based on GPS-TEC data have been reported so far (e.g., Heki, 2006; Dautermann et al., 2009; Heki et al., 2010). These studies reported that acoustic waves excited by volcano eruptions reach up to the F-region ionosphere, and caused F-region perturbations. After eruption of the Kelud Volcano, Indonesia, in February 2014, acoustic resonance between the Earth’s surface and lower thermosphere was reported based on TEC data and the seismic wave data (Nakashima et al., 2015). However, little studies on the D-region ionosphere associated with volcano eruptions have been reported. In this study, we investigate the D-region effects of eruptions of Sakurajima volcano (31.59N, 130.66E), Japan, at 04:11 UT on June 6, 2014, using intensity perturbation of VLF/LF transmitter signals. The VLF/LF propagation paths use in this study are JJY (JJY 60 kHz) - Tainan (TNN, Taiwan), and JJI (22.2 kHz) - TNN. Based on wavelet spectra, the perturbation of both transmitter signals had a frequency of 2-6 mHz during 04:12-04:30 UT after the eruptions (04:11 UT).We compared the perturbations with atmospheric pressure data obtained by an infrasonic meter observed by Sakurajima Volcano Research Center, Kyoto University, and seismic waves in the NIED F-net data (FUK, STM, and SBR) located close to the JJY-TNN path. The atmospheric pressure and vertical velocity of the seismic waves had the similar frequencies of 2-10 mHz during 04:12-04:47 UT. These similar frequencies suggest that the perturbations would be caused by acoustic resonance between the Earth's surface and lower thermosphere, or by acoustic and atmospheric gravity waves generated by volcanic eruptions. In the presentation, we will discuss the cause of the VLF/LF perturbations in more detail.