Abstract: To compare the differences in propagation characteristics between Large Scale Traveling Atmospheric Disturbances (LSTAD) and Large Scale Traveling Ionospheric Disturbances (LSTID) that propagate concomitantly in the thermosphere-ionosphere, this study takes advantage of the CHAMP satellite’s capability to perform simultaneous co-volume cross-latitude observations of atmospheric mass density and electron density, and investigates an event of a pair of long-distance concomitantly propagating LSTAD and LSTID on 19 March 2002.
 
Accompanying a sudden significant enhancement in the AE index around 0400–0600 UT on 19 March, the CHAMP satellite subsequently observed the concomitantly propagating LSTAD and LSTID in the Northern Hemisphere. Within approximately 6 hours after 0400 UT, these atmospheric mass density and electron density disturbances propagated continuously southward, crossed the equator into the Southern Hemisphere, and finally dissipated and vanished in the Southern Hemisphere.
 
In addition, observations from ground-based GNSS receiver chains confirm the existence of the LSTID detected by the satellite. Comparative analysis shows that since electron motion is strongly controlled by the Lorentz force while neutral particles are not constrained by it, the meridional horizontal propagation velocities of LSTAD and LSTID excited from the same source region and propagating concomitantly exhibit obvious differences. Therefore, the phases of the two disturbances at the same time and location along the same orbit are not identical, and can even differ significantly.