14:45 〜 15:00
[PEM14-17] Structures of ionospheric disturbances by using improved GNSS-based 3-D tomography
キーワード：電離圏トモグラフィー、電離圏リアルタイム連続観測、電離圏擾乱、電離圏3次元構造
Computerized Ionospheric Tomography (CIT) based on GNSS data is a powerful tool to study 3-D structures of the ionosphere.
We have developed a near-realtime regional ionospheric tomography system over Japan by using 200 selected stations of GEONET (GNSS Earth Observation Network) operated by Geospatial Information Authority of Japan (GSI). It has been operated since 2016.
Although the system generally performs well, it was also noticed that the ionospheric heights were sometimes overestimated when the true heights were quite low. To overcome this, assimilating ionosonde observation data into the 3-D tomography was proposed (Ssessanga et al., 2021).
We further refine the algorithm by optimizing the co-variance matrices and the cost function to be minimized. With this refinement, the ionospheric heights were better reproduced as compared with independent incoherent scatter measurement results by the MU radar. The system can still be operated in near-realtime with latency of a few to several minutes.
By using the improved tomography system, we investigated distinct ionospheric disturbances associated with severe geomagnetic storms occurred in 2023-2024. Signatures of polarization electric field are captured as the vertical displacements of the ionosphere. Thus, the improved 3-D tomography is very useful to study structures and mechanisms of ionospheric disturbances.
We have developed a near-realtime regional ionospheric tomography system over Japan by using 200 selected stations of GEONET (GNSS Earth Observation Network) operated by Geospatial Information Authority of Japan (GSI). It has been operated since 2016.
Although the system generally performs well, it was also noticed that the ionospheric heights were sometimes overestimated when the true heights were quite low. To overcome this, assimilating ionosonde observation data into the 3-D tomography was proposed (Ssessanga et al., 2021).
We further refine the algorithm by optimizing the co-variance matrices and the cost function to be minimized. With this refinement, the ionospheric heights were better reproduced as compared with independent incoherent scatter measurement results by the MU radar. The system can still be operated in near-realtime with latency of a few to several minutes.
By using the improved tomography system, we investigated distinct ionospheric disturbances associated with severe geomagnetic storms occurred in 2023-2024. Signatures of polarization electric field are captured as the vertical displacements of the ionosphere. Thus, the improved 3-D tomography is very useful to study structures and mechanisms of ionospheric disturbances.