[M-TT37] 稠密多点GNSS観測が切り拓く地球科学の新展開

[MTT37-10] High-Resolution 3-D GNSS Tomography of Medium-Scale Traveling Ionospheric Disturbances Driven by Atmospheric Gravity Waves Over Japan

*傅 維正¹、大塚 雄一¹、Hocke Klemens²、馬 冠一³、西岡 未知⁴、陣 英克⁴ (1.名古屋大学 宇宙地球環境研究所、2.Institute of Applied Physics, University of Bern, Bern, Switzerland 、3.National Astronomical Observatories, Chinese Academy of Sciences, Beijing, China、4.National Institute of Information and Communications Technology, Tokyo, Japan)

Medium-scale traveling ionospheric disturbances (MSTIDs) are a common type of ionospheric perturbations frequently observed at mid-latitudes. Atmospheric gravity waves (AGWs) serve as an important source for their generation. This study reconstructs the three-dimensional (3-D) structures of medium-scale traveling ionospheric disturbances (MSTIDs) driven by AGWs at summer sunrise and sunset terminators, using a computerized ionospheric tomography (CIT) technique based on ultra-dense Global Navigation Satellite System (GNSS) observations over Japan. Two representative events were analyzed in detail. The reconstruction results reveal that MSTID-induced electron density perturbations predominantly occur at altitudes of 200–400 km, with vertical wavelengths of approximately 250 km. Notably, the MSTID bands are vertically tilted and exhibit a downward phase progression along their propagation direction. Calculations based on AGW dispersion relations show strong agreement between the theoretical predictions and the reconstructed vertical wavelengths. For the first time, the detailed 3-D structures of MSTIDs driven by AGWs are reconstructed by GNSS measurements. These findings highlight the effectiveness of the 3-D CIT technique in resolving ionospheric disturbances with high spatial and temporal resolution, offering a robust tool for identifying disturbances from different sources and advancing our understanding of ionospheric dynamics.


Acknowledgements
The GNSS observation data from SoftBank used in this study were provided by SoftBank Corp. and ALES Corp. through the Consortium to utilize the SoftBank original reference sites for Earth and Space Science.