14:00 〜 14:15
[PEM12-08] 2025年1月1日磁気嵐時に東北北部にまで広がったプラズマバブル
キーワード：プラズマバブル、磁気嵐、宇宙天気、光学観測、GEONET
We report a northern most optical emission of plasma bubble extending to the northern Tohoku area during a magnetic storm event on Jan. 1, 2025. We developed the monochromatic all-sky camera at a wavelength of OI 630nm which is the same all-sky camera system as installed at the Syowa, Davis, Casey, Dumont d’Urville, and Concordia (Dome-C). The all-sky camera system consists of CMOS sensor (ZWO ASI183MM Pro), fisheye lens (Fujinon FE185C086HA, f=2.7 mm, F/1.8), and Edmund interference filter. The cameras are controlled by Linux mini-PCs (ESC LIVA-Q2, OS). The data are stored on a RAID-1 NAS (Synology DS223j). The LIVA PCs, NAS and router are powered by an internet switch (Watchboot). We installed the all-sky camera at the Iitate Station of PPARC, Tohoku University on Nov. 29, 2024, and started the continuous operation every night with an exposure time of ~ 3 min.
A major magnetic storm occurred on Jan. 1, 2025 with the Dst index reaching to -221 nT at 17UT. There are reports that low-latitude auroras appeared at several locations in Hokkaido and Iwate prefectures. During this night, the weather of Iitate Station is partially cloudy, and we could sometimes see stars and 630nm airglow emission with clear sky conditions. After 19UT, sky was almost clear, particularly in the north direction, and we see the enhance of 630nm emission in the northern horizon. We suggest that the northern emission would be low-latitude aurora.
In this presentation, we fucus on two emission bands extending from north to south in the all-sky field-of-view during the period from ~19:20 UT to dawn twilight (~20:40 UT). The emission bands moved almost correlated with the rotation of Earth, and also drifted to the north-west direction. At almost the same timing from 19:10 UT, the enhanced Rate of TEC change Index (ROTI) area expanded from the Kanto area (36 deg Glon.) to the north of Tohoku (42 deg Glon) obtained from GNSS Earth Observation Network (GEONET) data. The ROTI area has several sub-structures extending in the north-south direction with a typical width of several hundred km, and it expanded to north, slightly drifted westward, and continued until ~22UT. From the ROTI data, we suggest the north-south enhancement of ROTI and optical emission structure implies plasma bubble caused by strong equatorial electric field during the major magnetic storm. From the fact that the ROTI reached the northern Tohoku considering its magnetic latitude (~33 Mlat), the maximum altitude of plasma bubble would exceed 2500km. The plasma bubble was also observed by the OMTI-all sky imager at Shigaraki in the south around 11-14UT, and the bubble has spread across the entire sky by ~20 UT. Surprisingly, the same plasma bubble was seen in the southern FOV of image taken by the OMTI imager at Rikubetsu around 20 UT.
The event that the plasma bubble extended to the north Tohoku during the major magnetic storm indicates that ionospheric disturbances directly above the Kanto metropolitan area could cause a degradation of pointing accuracy, and therefore, it has valuable in terms of the space weather. In the presentation, we give the detailed data analysis obtained with optical network of Shigaraki, Iitate and Rikubetu, and GNSS network.
A major magnetic storm occurred on Jan. 1, 2025 with the Dst index reaching to -221 nT at 17UT. There are reports that low-latitude auroras appeared at several locations in Hokkaido and Iwate prefectures. During this night, the weather of Iitate Station is partially cloudy, and we could sometimes see stars and 630nm airglow emission with clear sky conditions. After 19UT, sky was almost clear, particularly in the north direction, and we see the enhance of 630nm emission in the northern horizon. We suggest that the northern emission would be low-latitude aurora.
In this presentation, we fucus on two emission bands extending from north to south in the all-sky field-of-view during the period from ~19:20 UT to dawn twilight (~20:40 UT). The emission bands moved almost correlated with the rotation of Earth, and also drifted to the north-west direction. At almost the same timing from 19:10 UT, the enhanced Rate of TEC change Index (ROTI) area expanded from the Kanto area (36 deg Glon.) to the north of Tohoku (42 deg Glon) obtained from GNSS Earth Observation Network (GEONET) data. The ROTI area has several sub-structures extending in the north-south direction with a typical width of several hundred km, and it expanded to north, slightly drifted westward, and continued until ~22UT. From the ROTI data, we suggest the north-south enhancement of ROTI and optical emission structure implies plasma bubble caused by strong equatorial electric field during the major magnetic storm. From the fact that the ROTI reached the northern Tohoku considering its magnetic latitude (~33 Mlat), the maximum altitude of plasma bubble would exceed 2500km. The plasma bubble was also observed by the OMTI-all sky imager at Shigaraki in the south around 11-14UT, and the bubble has spread across the entire sky by ~20 UT. Surprisingly, the same plasma bubble was seen in the southern FOV of image taken by the OMTI imager at Rikubetsu around 20 UT.
The event that the plasma bubble extended to the north Tohoku during the major magnetic storm indicates that ionospheric disturbances directly above the Kanto metropolitan area could cause a degradation of pointing accuracy, and therefore, it has valuable in terms of the space weather. In the presentation, we give the detailed data analysis obtained with optical network of Shigaraki, Iitate and Rikubetu, and GNSS network.