[P-EM09] Space Weather and Space Climate

[PEM09-P20] LバンドInSARとマルチGNSS-TEC法によるSporadic E層の検出

藤本 達也¹、*古屋 正人¹、日置 幸介¹ (1.北海道大学大学院理学研究院地球惑星科学部門)

キーワード：スポラディックE層、GNSS-TEC、InSAR

The sporadic E (Es) occurs sporadically in the E region of the ionosphere with anomalously high electron density patches. This phenomenon is known to affect the propagation of radio waves, especially in the VHF band. However, the conventional pointwise ionosonde measurements were sparsely distributed, and the detailed spatial structure of the Es remained uncertain. The dense GNSS observation network allowed to reveal the details of Es events with the use of GNSS TEC (e.g., Maeda and Heki, 2014), but even the Japanese GEONET has an average spatial separation of ~20km. Maeda et al (2016) first succeeded in observing an Es event using ALOS interferometric synthetic aperture radar (InSAR), and Furuya et al (2017) further applied the range split-spectrum method (SSM) to two Es episodes. In this study, we detected another Es episode using ALOS-2 data as well as GNSS TEC from both GEONET and the SoftBank Corp. network. We confine our investigation to daytime Es and thus examine only the ALOS-2 from descending orbits. We confirmed that L-band InSAR could provide higher spatial resolution than the multi GNSS(Global Navigation Satellite System)-TEC(Total Electron Content) method. Unlike the two cases in Furuya et al (2017), the dispersive and non-dispersive phases could be rather well-separated in the present Es episode on June 26, 2020, near Shikoku. The secondary anomaly marginally detected in GNSS-TEC could be confirmed in the InSAR data as well.

Acknowledgment: The SoftBank's GNSS observation data used in this study was provided by SoftBank Corp. and ALES Corp. through the framework of the "Consortium to utilize the SoftBank original reference sites for Earth and Space Science".