[P-EM12] Coupling Processes in the Atmosphere-Ionosphere System

[PEM12-P23] Quantitative analysis of ionospheric disturbances caused by typhoons using Total Electron Content maps and magnetic field data

*Nishimura Miki¹, Akimasa Yoshikawa¹, Yuki Obana¹ (1.Department of Earth and Planetary Sciences, Kyushu University)

Keywords:Ionospheric disturbances, typhoon, geomagnetism, total electron content

Recent studies have elucidated the significant impact of intense tropospheric convective activities, such as typhoons, on the ionosphere. A pivotal approach to characterizing the ionospheric environment's variability involves observing the Total Electron Content (TEC) utilizing Global Positioning System (GPS) data. While prior research has focused on analyzing individual or a limited number of ionospheric disturbances triggered by typhoons, the correlation between such disturbances and magnetic field fluctuations remains underexplored. This study conducts a quantitative analysis of ionospheric disturbances induced by typhoons through TEC maps generated from GPS data. Moreover, an in-depth examination of magnetic field data from the MAGDAS (Magnetic Data Acquisition System) global magnetic field observation network, operated by the International Center for Space Weather Science and Education at Kyushu University, unveils the dynamics of ionospheric currents in response to electron density fluctuations. We leveraged publicly available, detrended TEC data from the National Institute of Information and Communications Technology (NICT), focusing on ten typhoons that approached or made landfall in Japan during geomagnetically quiet days between 2019 and 2021. Our findings reveal distinct TEC variations throughout the typhoon events. Specifically, during typhoon passages, TEC variations exhibited three patterns: (A) monotonically increasing, (B) increasing with spatial transitions, and (C) monotonically decreasing. Among the ten typhoons analyzed, seven events were categorized as type (A), one as type (B), and two as type (C). Notably, type (B) events could be linked to medium-scale traveling ionospheric disturbances occurring at night. These phenomena are discussed by correlating detrended TEC maps with ionospheric currents derived from MAGDAS magnetic field data.