[P-EM22] [JJ] 大気圏・電離圏

[PEM22-06] Variations in the D-region heights during the total solar eclipse of 9 March 2016 in Insonesia using AVON data

*大矢 浩代¹、深山 恭平、土屋 史紀²、中田 裕之¹、山下 幸三³、高橋 幸弘⁴ (1.千葉大学大学院工学研究科、2.東北大学大学院理学研究科惑星プラズマ・大気研究センター、3.サレジオ工業高等専門学校、4.北海道大学大学院理学研究院)

We report increase in the reflection heights of LF transmitter signals during a total solar eclipse in Indonesia on 9 March, 2016, using AVON (Asia VLF Observation Network) data. The transmitter signals of JJY-Fukushima (FKS, 40 kHz), JJY-Saga (SAG, 60 kHz), and BPC (China, 68.5 kHz) were received at Pontianak (PTK), Indonesia, where the maximum magnitude of the solar eclipse was 0.929 at 00:25 UT. The magnitude of the solar eclipse at the transmitter sites was about 0.2. The all paths did not cross the eclipse path. During the solar eclipse (00:00 – 01:30 UT), the average changes of the phase delay of the SAG-PTK and BPC-PTK paths were 40º and 42º, respectively. Assuming a usual daytime height for the LF waves to be 70 km, the phase delays on both the SAG-PTK and BPC-PTK paths correspond to the increase in the reflection heights of about 1.5 km based on the Earth-ionosphere waveguide mode theory. The LF intensity of the FKS-PTK path during the solar eclipse was slightly larger by about 6.5 dB than that before and after the eclipse time. The increase in the LF reflection heights suggests the decrease in the D-region electron density during the solar eclipse.