Japan Geoscience Union Meeting 2018

Presentation information

[JJ] Oral

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

[P-EM18] Physics and Chemistry in the Atmosphere and Ionosphere

Tue. May 22, 2018 1:45 PM - 3:15 PM 304 (3F International Conference Hall, Makuhari Messe)

convener:Yuichi Otsuka(Institute for Space-Earth Environmental Research, Nagoya University), Takuya Tsugawa(National Institute of Information and Communications Technology), Seiji Kawamura(国立研究開発法人 情報通信研究機構), Chairperson:Yuta Hozumi(電気通信大学), Otsuka Yuichi

2:45 PM - 3:00 PM

[PEM18-05] Examination of vertical distributions of coseismic ionospheric disturbances using GPS occultation observation.

*Yuta Inoue1, Hiroyuki Nakata2, Hiroyo Ohya2, Toshiaki Takano2 (1.Graduate School of Science and Engineering, Chiba university, 2.Graduate School of Engineering, Chiba university)

Keywords:earthquake, ionospheric disturbance, occultation observation

It is reported that ionospheric disturbances are caused by large earthquakes. One of the causes is the infrasound wave excited by surface waves propagated on the ground from the epicenter. The characteristics of the ionospheric disturbances horizontally propagated after large earthquake have been examined by using a network of ground-based GPS receivers. On the other hand, the vertical propagation of coseismic ionospheric disturbances are rarely reported.
In this study, to examine the vertical propagation of the ionospheric disturbances, we have examined electron density profiles observed by GPS radio occultation measurements of FORMOSAT-3/COSMIC satellites.
We analyzed the Tohoku Earthquake (M9.0) occurred at 5:46:18 on 11th March 2011 (UTC). Density profiles located within 30 degrees both of latitude and longitude one hour of the earthquakes were analyzed. To extract the coseismic disturbances, we calculated the mean value of the electron density in the vertical direction using five-point data (corresponds to about 8 km) and extracted the disturbance from the difference between the mean value and the raw data. Variations of about 5000 electrons per cubic centimeter at two different data were observed at an altitude of 200 ~ 600 km. We also calculated propagation velocity and propagation time of the perturbations from the epicenter to the observation point. It is confirmed that the disturbances are occurred due to the earthquake.