Explosive Eruption of the Tonga Underwater Volcano Modulates the Ionospheric E‐Region Current on 15 January 2022

The sudden eruption of the Tonga underwater volcano (20.53°S, 175.38°W) on 15 January 2022 generated explosions that triggered blast waves traveling away from the eruption. In this study, the analysis of the geomagnetic field observations on the ground shows that the eruption perturbed the E‐region current density by 22–55 mA/m within a radius of 8,000 km away from the eruption. The perturbation evolved into large scales of ∼5 hr and thousands of kilometers as it traveled away. The traveling speed of the leading front is ∼740 m/s that is near acoustic in the ionosphere. The magnetic fields and total electron content observations suggest that the dynamics changes further induced significant ionospheric disturbances that lasted ∼10 hr after the eruption. The examination of the Tonga volcanic eruption inspires us that a near‐surface perturbation can change the dynamics of the upper atmosphere. Plain Language Summary As we drop a stone into the still water, the water piles up around the rock and induces ripples in the form of concentric circles that expand and travel away from the center point. A similar phenomenon happened in the atmosphere after the eruption of the Tonga underwater volcano (20.53°S, 175.38°W) at ∼04:15 UT on 15 January 2022. The Earth's atmosphere is a pond of air. The explosive eruption triggered prosperous waves, which is similar to dropping a stone into water. The waves, ripples, and disturbances in different spheres are fantastic due to the eruption (Figure S8 in Supporting Information S1). Besides the tsunamis, atmospheric concentric ripples, and ionospheric traveling disturbances, this study for the first time showed that the blast wave due to the eruption changed the dynamics of the ionosphere or thermosphere (upper atmosphere). It is well known that a significant volcanic eruption can release tremendous ashes and gases into the troposphere and stratosphere (lower atmosphere), which change the chemical and dynamic process there. The observations in this study surprisingly show that the eruption changed the dynamics of the upper atmosphere, where the volcanic cloud cannot reach. Key Points The eruption of the Tonga underwater volcano perturbed the E‐region current and, in turn, changed the geomagnetic field by ∼20–50 nT A large near‐surface perturbation can modulate the ionospheric dynamics and further induce ionospheric disturbances The significant ionospheric disturbances with periods ranging from several minutes to hours lasted more