Simultaneous Observation of Equatorial Plasma Bubbles and Traveling Ionospheric Disturbances Over Indonesia Following the 15 January 2022 Tonga Volcano Eruption

Abstract We report our analysis of multi‐diagnostic ionospheric observations over Indonesia following the 15 January 2022 Tonga volcano eruption. Observation data from the Indonesian global navigation satellite system (GNSS) CORS network, ionosondes, and GNSS ionospheric scintillation and TEC monitor receivers, in conjunction with the Himawari‐8 satellite imagery, were used in the analysis. The Lamb waves from the eruption, traveling at 310 m/s, reached eastern part of Indonesia (5,000 km from Tonga) approximately 4 hr after the eruption. The Lamb waves traversed the Indonesian region for 4 hr and 40 min, around sunset period. As a result, some unseasonal equatorial plasma bubbles (EPBs) occurred over this longitude sector, with an interesting initial development pattern. There was a directional split in the zonal drift velocity of these EPBs, where some EPBs drifted eastward with a velocity of 138.0 6.9 m/s and others westward with a velocity of 39.6 2.0 m/s. At the same time, traveling ionospheric disturbances (TIDs) from the Tonga eruption also propagated over the Indonesian region with a velocity of 434.6 21.7 m/s. In the total electron content (TEC) data, interactions between EPBs and TIDs were observed over the region. There were enhancements in the rate‐of‐TEC index (ROTI) and scintillation index, indicating the presence of ionospheric density irregularities. A turbulent ionospheric F‐layer, due to these EPBs and TIDs, caused either spread‐F echoes or a loss of F‐region traces in the ionograms. An intensification of sporadic‐E layer, lasting for a few hours, was also observed in the ionograms.