An Investigation on the Ionospheric Response to the Volcanic Explosion of Hunga Ha'apai, 2022, Based on the Observations from the Meridian Project: The Plasma Drift Variations

The Hunga Ha'apai volcano eruption (20.536 degrees S, 175.382 degrees W in Tonga) reached its maximum outbreak on 15 January 2022, at 04:15 UT, leading to huge oceanic fluctuations and atmospheric disturbances. This study focuses on the response of the ionosphere to the eruption of Tonga volcano, based on observations from a low-latitude station of the Meridian Project at Fuke, Hainan (19.310 degrees N, 109.080 degrees E). We identified the anomalies in the plasma drift caused by the volcanic eruption and discussed the possible mechanisms. The following results were obtained: (1) The anomalies of ionospheric plasma drift were observed at Fuke Station, during the main eruption; (2) A sudden increase and inversion of the plasma drift velocity occurred on January 15, and a large fluctuation of the drift velocity occurred afterwards; (3) By comparing the anomalous propagation velocity with the background drift, it was confirmed that the anomaly was the response of the low latitude ionosphere to the Tonga volcano eruption. Furthermore, we analyzed a possible mechanism for the effect of volcanic eruptions on ionospheric plasma drift. A large number of charged particles could be brought out by the explosion to generate an atmospheric electric field, which may cause the ionospheric plasma to change its original motion.