Three-Dimensional Ionospheric Evolution of Electron Density Depletion Induced by a Long March 2D Rocket Launch

Abstract

Using GNSS-TEC observations and the computerized ionospheric tomography (CIT) technique, we investigated the three-dimensional structure and spatiotemporal evolution of the ionospheric electron density depletion induced by the LM-2D rocket launch on 17 January 2022. The depletion appeared at ∼7 min after liftoff, initially concentrated at altitudes of 200–400 km and horizontal distances of 470–1,290 km from the launch site, with a magnitude of ∼−1 × 10¹¹ to −2 × 10¹¹ el m⁻³. It subsequently intensified and expanded vertically to ∼160–430 km altitude and horizontally to ∼2,000 km along the reference trajectory. The timing of the peak depletion exhibited a clear altitude dependence, with the maximum depletion of ∼−6.0 × 10¹¹ el m⁻³ occurring at ∼310 km at ∼40 min after liftoff, while the peak occurred progressively later at higher altitudes, at ∼50 min at 370 km and ∼80 min at 430 km. This altitude-dependent timing is consistent with the upward diffusion of rocket exhaust. The depletion persisted longest near ∼300 km altitude and became undetectable by ∼140 min after liftoff, with more rapid decay at higher altitudes likely associated with increasing diffusion coefficients with altitude. The depletion axis also showed an apparent westward displacement that varied with altitude and time. The observed displacement likely reflects the combined effects of pressure-bulge-related redistribution, background neutral winds, ionospheric electrodynamic transport, diffusion, and the evolving three-dimensional morphology of the depletion.