Large‐Scale Disturbances in the Upper Thermosphere Induced by the 2022 Tonga Volcanic Eruption

The effects of volcanic eruptions on the ionosphere have been well studied, however, evidence for the anticipated upper atmospheric neutral variations and their exact extents of change are rarely available. Here, we report dramatic thermospheric disturbances following the 15 January 2022 Tonga eruption. The GRACE‐FO and Swarm‐C observations from the accelerometers exhibited three successive thermospheric density waves at ∼500 km altitudes propagating concentrically across the globe at 200–450 m/s phase speed and two of the three waves converged at the antipode of the epicenter. A large‐scale and long‐lasting neutral density depletion within a radius of approximately 10,000 km around the epicenter occurred, along with the density enhancement around the antipode of the epicenter. Such an enhancement is comparable in the relative intensity with respect to the no‐eruption condition, to the effect of a moderate geomagnetic storm. This study offers observational evidence of substantial global upper thermospheric perturbations well above their origin near the Earth's surface due to a volcanic eruption. Plain Language Summary Extreme volcanic eruptions can discharge large amounts of energy into the Earth's system, triggering earthquakes, tsunamis, and potentially a series of atmospheric waves. These waves propagate outward from the epicenter and upward into space. We report significant thermospheric density waves excited by the 2022 Tonga volcanic eruption that propagated concentrically and globally. After the eruption, crater‐like density depletion was found around the eruption center, within a radius of approximately 10,000 km. Additionally, density enhancement was detected around the antipode of the epicenter. As a result of this local eruption on the Earth's surface, the global neutral density 500 km above the ground was significantly redistributed, with lower density in the volcanic eruption hemisphere and higher density in the antipode hemisphere. The impact of this eruption on the thermosphere is comparable to that of a moderate geomagnetic storm. Key Points The Tonga volcanic eruption induced significant disturbances in the thermospheric density up to 500 km satellite orbiting altitudes The eruption excited three successive thermospheric waves that propagated globally and two of them converged at the antipode of the epicenter Large‐scale and long‐lasting density depletion within a radius of about 10,000 km around the epicenter occurred after the eruption