Work

Analysis of Tonga eruption-induced disturbances in the upper thermosphere based on atmospheric drag accelerations from LEO satellites

Year: 2026

Type: article

Abstract: The violent eruption of the Tonga volcano on 15 January 2022 triggered significant disturbances in the atmosphere and ionosphere. However, limited observational capabilities have persistently hindered the characterization of eruption-induced neutral density disturbances in the upper thermosphere. In this study, the atmospheric drag accelerations of five low Earth orbit (LEO) satellites operating at altitudes at ~ 430 km and ~ 500 km, including SWARM-A/B/C and GRACE-C/D, are derived from reduced-dynamic precise orbit determination. Based on these data, possible anomalous perturbations associated with the Tonga eruption are identified, and their propagation characteristics are further analyzed. Following the eruption, between 08:00 and 16:00 UT, a large-scale density depletion centered around Tonga with a radius of approximately 10,000 km is observed, nearly covering the regions of Australia and the Pacific Ocean. In addition, a significant density enhancement is detected to the west of the antipode. Analysis results indicate that these large-scale disturbances in atmospheric drag (AD) acceleration are more likely caused by the propagation of gravity waves (GWs), with vertical speeds $$\:{c}_{V}\cong\:$$ 40.3–67.6 m/s, horizontal speeds $$\:{c}_{H}\cong\:$$ 613.9–677.1 m/s at ~ 500 km height and $$\:{c}_{H}\cong\:$$ 568.0–593.9 m/s at ~ 430 km height. Moreover, a comparison of AD acceleration variations from SWARM-A and SWARM-B suggests that neutral density disturbances caused by GWs may take longer to dissipate at higher altitudes. However, a definitive explanation for this phenomenon remains unclear at present. This study demonstrates the feasibility of using LEO satellites as mobile “cameras” to detect natural hazards-induced neutral density disturbances at their orbital altitudes. Additionally, the dynamic orbits and limited availability of LEO satellites make it difficult to capture large-scale, simultaneous observations of neutral density. Nevertheless, with the ongoing development of LEO satellite constellations, such capability is promising and highly anticipated.

Source: GPS Solutions

DOI: 10.1007/s10291-026-02150-5