Japan Geoscience Union Meeting 2015

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Oral

Symbol M (Multidisciplinary and Interdisciplinary) » M-IS Intersection

[M-IS27] Electromagnetic phenomena associated with seismic and volcanic activities

Tue. May 26, 2015 4:15 PM - 6:00 PM 201A (2F)

Convener:*Tetsuya Kodama(Earth Observation Research Center, Space Applications Mission Directorate, Japan Space Exploration Agency), Yasuhide Hobara(Graduate School of Information and Engineering Department of Communication Engineering and Informatics, The University of Electro-Communications), Toshiyasu Nagao(Earthquake Prediction Research Center, Tokai University), Masashi Hayakawa(University of Electro-Communications), Chair:Masashi Hayakawa(Hayakawa Institute of Seismo Electromagnetics Co. Ltd.), Yasuhide Hobara(Graduate School of Information and Engineering Department of Communication Engineering and Informatics, The University of Electro-Communications)

5:00 PM - 5:15 PM

[MIS27-06] Statistical characteristics of the Ionsopheric TEC disturbances over Japan area

*Ayano HONMA1, Peng Han2, Katsumi HATTORI2, Jann-yenq LIU3 (1.Faculty of Science, Chiba University, 2.Graduate School of Science, Chiba University, 3.National Central University, Taiwan)

Keywords:statistical analysis, geomagnetic storm, Ionsopheric TEC disturbances, bootstrap method, earthquake

To reduce the effect of strong geomagnetic activities such as geomagnetic storms, the TEC data of 2 days after Dst index exceed -60 nT were excluded in previous statistical studies of earthquake related TEC anomalies. Actually, the influences of a magnetic storm on TEC variations depend on the intensity and onset time of the storm. In this study, to clarify such dependences, we applied classification analysis method to the storm data (Dst) and discussed the response of TEC variation to each type of storm.
We picked out all the 294 geomagnetic storms during 1998-2013, and classified them into 3 types according to its magnitude and 4 types according to the onset time (local time). We checked the TEC data from 2 days before till 5 days after the onset of each geomagnetic storm. A bootstrap method (10000 times extraction) is used to calculate the average variation of the TEC for each type of storm. The average variation can be regarded as an average response of TEC to the related type of storm. If the average value of TEC exceeds the mean±2σ threshold, we consider it being affected by the storm. By this mean, we could find the accurate period affected by each type of storm.