JpGU-AGU Joint Meeting 2017

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[JJ] Oral

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

[P-EM22] [JJ] Physics and Chemistry in the Atmosphere and Ionosphere

Thu. May 25, 2017 10:45 AM - 12:15 PM A02 (Tokyo Bay Makuhari Hall)

convener:Yuichi Otsuka(Institute for Space-Earth Environmental Research, Nagoya University), Takuya Tsugawa(National Institute of Information and Communications Technology), Seiji Kawamura(National Institute of Information and Communications Technology), Chairperson:Hiroyo Ohya(Graduate School of Engineering, Chiba University), Chairperson:Michi Nishioka(National Institute of Information and Communications Technology)

12:00 PM - 12:15 PM

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

*Hiroyo Ohya1, Kyohei Miyama, Fuminori Tsuchiya2, Hiroyuki Nakata1, Kozo Yamashita3, Yukihiro Takahashi4 (1.Graduate School of Engineering, Chiba University, 2.Planetary Plasma and Atmospheric Research Center, Graduate School of Science, Tohoku University , 3.Salesian Polytechnic, 4.Graduate School of Science, Hokkaido University)

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.