Polar Vortex Strength Impacts on the Longitudinal Structure of Thermospheric Composition and Ionospheric Electron Density

This work examines the weak stratospheric polar vortex event in late February 2008 and the strong polar vortex event in late February 2021 to understand the potential influence of polar vortex strength on midlatitude thermospheric composition and ionospheric plasma density. The weak polar vortex event shows a reduction in thermospheric O/N₂ at all longitudes, changes in the ionospheric total electron content (TEC) that vary with longitude, and an intensification of the semidiurnal tides. The strong polar vortex event shows O/N₂ elevated by up to 25% in the Asian sector and a 25% decrease in semidiurnal tidal amplitude. The TEC response during the strong polar vortex event is complex and shows enhanced TEC in the Asian sector where O/N₂ is elevated. These are the first observations of anomalies in the thermospheric composition and ionospheric plasma associated with a strong polar vortex event.