Japan Geoscience Union Meeting 2022

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[E] Oral

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

[P-EM13] Coupling Processes in the Atmosphere-Ionosphere System

Tue. May 24, 2022 3:30 PM - 5:00 PM 302 (International Conference Hall, Makuhari Messe)

convener:Huixin Liu(Earth and Planetary Science Division, Kyushu University SERC, Kyushu University), convener:Yuichi Otsuka(Institute for Space-Earth Environmental Research, Nagoya University), Loren Chang(Institute of Space Science, National Central University), convener:Yue Deng(University of Texas at Arlington), Chairperson:Hiroyo Ohya(Graduate School of Engineering, Chiba University), Michi Nishioka(National Institute of Information and Communications Technology), Susumu Saito(Electronic Navigation Research Institute, National Institute of Maritime, Port, and Aviation Technology)


3:45 PM - 4:00 PM

[PEM13-08] Vertical ground motion and ionosphere before Kumamoto earthquake

*Koichiro Oyama1, C.H. Chen2 (1.International Center for Space Weather Study and Education, Kyushu University, 2.Departments of Earth Sciences, National Cheng Kung University, Tainan, Taiwan)

Keywords:Vertical ground motion, Ionosphere, Dynamo electric field

We studied the role of vertical ground motion as a driving force to excite acoustic gravity wave, which disturbs the ionosphere before Kumamoto earthquake. Data acquired with the slant gages distributed around the epicenter of Kumamoto earthquake which occurred on 14 April 2016 are used. Power spectrum density (PSD) is calculated from the vertical components measured with the slant gages. When the PSD increases, Daytime NmF2 reduces, and night time NmF2 increases, which can be explained by the intensified dynamo electric field. Two conditions to disturb ionosphere by the small ground motion are; the period of ground motion should be shorter than 2 hour, and the ground motion should continuously exist at least for one day, so that wave energy is continuously injected to the atmosphere. The PSD shows the minimum 5 days before, increases 2 days before, and then reduces one day before, following the drastic increase. Large part of the frequency spectrum of the ground motion appears around several 10 minutes to 2 hours.