The Influence of Ionospheric Neutral Wind Variations on the Morphology and Propagation of Medium Scale Traveling Ionospheric Disturbances on 8th August 2016

This study reports a special case of the propagation and morphology of medium scale traveling ionospheric disturbances (MSTIDs) over middle-latitude China on the night of August 8, 2016. The MSTIDs were simultaneously observed by multi-instruments, including the all-sky imager, Swarm satellite, and global positioning system (GPS). The MSTIDs lasted for about 6 h in the field view of airglow imager, showing typical wavelength, phase velocity of 272-296 km and 67-250 m/s, respectively. In addition, the imagers show that the inclination angles of phase fronts for some MSTIDs were decreasing during their propagation, resulting in the propagation direction changed from southwestward to nearly westward. More interestingly, the MSTIDs began to dissipate in the airglow observation when they propagated to lower latitudes (below similar to 40 degrees N) whereas the MSTIDs at higher latitudes were still visible in the later local times. Simulation results from the Thermosphere-Ionosphere-Electrodynamics General Circulation Model are fairly consistent with the Fabry-Perot Interferometer (FPI) wind observations, which provide convincing explanation to show that the variations of ionospheric neutral winds might play important roles in the changes of propagation direction and the dissipation of MSTIDs.