16:00 〜 16:15
[MTT37-08] 3-D structure of the ionospheric disturbance associated with the intense magnetic storms in 2023 by GNSS tomography with a dense GNSS network data
キーワード：GNSS電離圏トモグラフィー、電離圏擾乱、プラズマバブル、地磁気嵐
As the solar activity is approaching to its maximum, number of strong ionospheric disturbance events associated with intense geomagnetic storms is increasing. With more and more reliance on GNSS-based social systems, understanding and predicting the occurrence of ionospheric disturbances becomes more and more important.
In the lower mid-latitude region, there are two types of ionospheric disturbances. One is the equatorial plasma bubbles (EPBs) which can occur even without geomagnetic disturbances. Another is those associated with intense geomagnetic storms which can reach higher latitudes than usual EPBs. However, the physics causing the ionospheric disturbances of the second type has not been well understood yet. Nishioka et al. (2009) called such a disturbance as "super medium-scale traveling ionospheric disturbance", while Maruyama et al. (2013) proposed a mechanism called "storm-induced plasma stream". To understand the mechanism, information on the 3-D ionospheric structures very useful.
Recently, techniques to reconstruct 3-D ionospheric density profiles by using data from a dense GNSS network have been available. Saito et al. (2017) developed a near-real time ionospheric 3-D tomography. Ssessanga et al. (2021) improved it by assimilating ionosonde data.
On 5 November and 1 December 2023, intense geomagnetic storms occurred and unusually strong ionospheric disturbances were observed over Japan up to 40 degrees North in geographic latitude. Variations in total electron contents (TECs) had periodic structure aligned in the northwest-southeast direction and localized within about 10 degrees in the longitude. We further applied the improved 3-D tomography and found that the disturbances were coincided with the region of background density enhancements. Details of the 3-D ionospheric structures are analyzed and geophysical mechanism leading to the disturbances will be discussed.
In the lower mid-latitude region, there are two types of ionospheric disturbances. One is the equatorial plasma bubbles (EPBs) which can occur even without geomagnetic disturbances. Another is those associated with intense geomagnetic storms which can reach higher latitudes than usual EPBs. However, the physics causing the ionospheric disturbances of the second type has not been well understood yet. Nishioka et al. (2009) called such a disturbance as "super medium-scale traveling ionospheric disturbance", while Maruyama et al. (2013) proposed a mechanism called "storm-induced plasma stream". To understand the mechanism, information on the 3-D ionospheric structures very useful.
Recently, techniques to reconstruct 3-D ionospheric density profiles by using data from a dense GNSS network have been available. Saito et al. (2017) developed a near-real time ionospheric 3-D tomography. Ssessanga et al. (2021) improved it by assimilating ionosonde data.
On 5 November and 1 December 2023, intense geomagnetic storms occurred and unusually strong ionospheric disturbances were observed over Japan up to 40 degrees North in geographic latitude. Variations in total electron contents (TECs) had periodic structure aligned in the northwest-southeast direction and localized within about 10 degrees in the longitude. We further applied the improved 3-D tomography and found that the disturbances were coincided with the region of background density enhancements. Details of the 3-D ionospheric structures are analyzed and geophysical mechanism leading to the disturbances will be discussed.