On the possibility of in situ shear excitation of vortical perturbations and their coupling with short-period gravity waves by airglow and ionosphere observations

• Published in: Journal of atmospheric and solar-terrestrial physics 2002-05, Vol.64 (8), p.1105-1116
• Main Authors: Didebulidze, G.G, Chilingarashvili, S.P, Toroshelidze, T.I, Murusidze, I.G, Kvavadze, N.D, Sharadze, Z.S
• Format: Article
• Language: English
• Subjects: Airglow; Atmospheric waves; Mesosphere–thermosphere–ionosphere coupling
• ISSN: 1364-6826; 1879-1824
• DOI: 10.1016/S1364-6826(02)00061-5

The essential part of in situ shear excited vortical perturbations (shear waves) at mesosphere–thermosphere heights is considered by use of airglow, from Abastumani (42.8°E, 41.8°N), and ionospheric, from Tbilisi (44.8°E 41.7°N), observations. One of the characteristic processes for excitation of vortical perturbations (shear waves) is a phenomenon of its possible transformation into short-period atmospheric gravity waves (GWs) with a frequency close to the Brunt–Väisälä frequency (BVf). More convenient condition for shear excitation of vortical perturbations and their transformation into short-period GWs at mesosphere–thermosphere heights appears on magnetically disturbed days and during the mid-latitude springtime transition. Nighttime observations of intensities of the hydroxyl OH(8-3) band, the oxygen green 557.7 and red 630.0 nm lines from Abastumani show a possible presence of shear excited vortical perturbations and an accumulation of wave energy by short-period GWs with frequencies close to BVf on magnetically disturbed days and during springtime transition. The amplitude amplification of short-period gravity waves is considered as a possible indicator of regional and planetary scale changes of the horizontal wind in the upper atmosphere.