Sporadic Ionospheric Structures Caused by Atmospheric Waves Evolving in the Inhomogeneous Horizontal Wind and their Coupling with the 557.7 nm and 630.0 nm Line Nightglow Intensity Variations

Abstract:

The variations characteristic for the short-period atmospheric gravity waves (AGWs) evolving in the horizontal shear flow and vortical-type perturbations (shear wave) can be observed in the mid-latitude oxygen green 557.7 nm and red 630.0 nm line nightglow intensities emitted from the lower thermosphere and the ionosphere F2 regions. These atmospheric waves evolving in the inhomogeneous horizontal wind can cause formation of the sporadic E (Es layer), multi-layered structures in the ionosphere F2 region and short-period variations of their electron/ions density. The wave-like structure in the mid-latitude green and red line intensities which can be accompanied by the Es formation is noted. The importance of AGW generation and dissipation in the tidal wind responsible for upper atmosphere-ionosphere coupling processes also is noted in the simultaneous nightglow observations of the 557.7 nm and 630.0 nm line intensities.

The impulse-like structures in the 630.0 nm line intensities with duration of about 3-4 hours can be caused by in situ excited shear wave and also by vertical propagation of the tidal wind. The possibility of the latter phenomena can be supported by observed simultaneous (3-4 hours duration) increase in the 557.7 nm and the 630.0 nm lines intensities on magnetically quiet periods.