[S-TT40] 合成開口レーダーとその応用

[STT40-09] 2024年5月の磁気嵐のALOS-2/PALSAR-2への影響

*古屋 正人¹、Muafiry Ihsan² (1.北海道大学大学院理学研究院地球惑星科学部門、2.BRIN)

キーワード：磁気嵐、電離層、だいち2号、合成開口レーダー、全電子数

The strongest geomagnetic storm over the last 20 years occurred in May 2024. In particular, from 11-12 May, low-latitude auroras could be observed even at northern Hokkaido. Here we examine its impact on the ALOS-2/PALSAR-2 imageries. ALOS-2/PALSAR-2 was performing its full-polarimetric SAR observations at a couple of tracks in Japan from May 10-12. We have analyzed the imageries acquired at an track near Hokkaido at 23:18 JST on 11 May 2024. To examine the effect of the ionospheric disturbances on the SAR image, we first split the original single-look-complex (SLC) images into forward- and backward-looking SLC images and then computed their offset field. Although this is not an interferometry, this approach is similar to the multiple-aperture interferometry that allows us to derive the along-azimuth gradient of total electron content (TEC) and azimuth displacements (if any). The derived apparent azimuth displacements were ranging -15 meters to +15 meters, which is greater than those we found during the sporadic-E episodes (Fujimoto et al. 2024). Regarding the spatial scale, the apparent azimuth displacements ranged from ~5-20km. However, those apparent displacements were restricted to only the southern-half portion of the entire imaged area.