Case Comparative of Simultaneous Observations of Large-scale Traveling Thermospheric and Ionospheric Disturbances

To compare the propagation characteristics of Large-Scale Traveling Atmospheric Disturbances (LSTAD) and Large-Scale Traveling Ionospheric Disturbances (LSTID) that propagate in tandem in the thermosphere-ionosphere, this paper takes advantage of the CHAMP satellite’s ability to simultaneously observe atmospheric mass density and electron density across latitudes, studying a pair of LSTAD and LSTID events that propagated in tandem over long distances on 19 March 2002. Around 04:00-06:00 UT on 19 March, with a sudden and significant increase in the AE index, the CHAMP satellite observed the LSTAD and LSTID propagating in tandem in the Northern Hemisphere. Over the next approximately 6 h after 04:00 UT, these disturbances in atmospheric mass density and electron density propagated southward, crossed the equator, and entered the Southern Hemisphere, eventually dissipating there. On the other hand, the ground-based GNSS chain observations also confirmed the existence of the LSTID observed by the satellite. Through comparative analysis, it was found that due to the highly controlled movement of electrons by the Lorentz force while neutral particles are not constrained by it, the horizontal propagation speeds of LSTAD and LSTID along the meridian direction show significant differences. Therefore, at the same time and position on the same orbit, their phases are not the same and may even differ significantly.