[P-EM12] Coupling Processes in the Atmosphere-Ionosphere System

[PEM12-04] Generation of Equatorial Plasma Bubbles by Marapi Volcano Eruption

*Septi Perwitasari¹、Michi Nishioka¹、Yuichi Otsuka²、Susumu Saito³、Asnawi Husein⁴、Annies Siradj Mardiani⁴、Pornchai Supnithi⁵、Punyawi Jamjareegulgarn⁶、Tharadol Komolmis⁷ (1.National Institute of Information and Communications Technology、2.Institute for Space-Earth Environmental Research, Nagoya University、3.Electronic Navigation Research Institute、4.National Research and Innovation Agency、5.King Mongkut's Institute of Technology Ladkrabang、6.King Mongkut's Institute of Technology Ladkrabang, Prince of Chumphon Campus、7.Chiang Mai University)

キーワード：Equatorial plasma bubbles, Volcano eruption

We report Equatorial Plasma Bubble (EPB) events on 3 December 2023 that were observed by various ionospheric monitoring instruments in Indonesia (Kototabang, Pontianak), Thailand (Chumphon, Chiang Mai), and Vietnam (Bac Lieu) almost simultaneously. The geomagnetic condition was in the recovery phase in which the generation of EPBs was unlikely. Another possible source is the Marapi Volcano eruption which is located in Kototabang, Indonesia (0.38°S, 100.47°E). The eruption was detected at 7:54 UT (14:54 LT) on 3 December 2023 and lasted for ~4 minutes. A harmonic oscillation associated with ionospheric disturbances was observed in the vertical total electron content (VTEC) change about 30 minutes after the eruption from a nearby GPS receiver (0.95°S, 100.37°S). A plasma bubble feature was observed in the VTEC (PRN no 7) data started around 12:15 UT. The nearest ionosonde station in Pontianak (0.003°S, 109.36°E) observed a spread-F from ~12:15 UT. VHF radar in Chumphon (10.72°N, 99.37°E) observed Field-Aligned Irregularities (FAIs) associated with EPB, which reached ~600 km altitude, shortly after 12:00 UT. At the same time, a spread-F and a plasma bubble feature were also observed from ~11:45 UT and 12:15 UT from the ionosonde and GPS TEC/ROTI data at the same location, respectively. Spread-F events were also observed over Chiang Mai (18.76°N, 98.93°E) from ~12:45 UT and Bac Lieu (9.30°N, 105.71° E) from ~11:45 UT). Sharp enhancements of virtual height (h’F) of the ionosphere F layer were observed from around 11 UT from all ionosonde stations leading to the spread-F events. The combination of disturbances in the bottom side of the ionosphere caused by the eruption and the upward motion of the ionosphere after sunset could cause these sharp enhancements. A detailed analysis of this event will be discussed in the presentation.