Excitation of green and red lines in the night airglow

Abstract

The rate of collisional deactivation of excited O atoms which leads to the emission of the λ5577 line in the night airglow has been estimated between the altitudes 50 and 200 km, after taking into account all processes by which these excited atoms may be quenched. The excitation mechanisms of this line are then considered in the light of recent rocket observations which give 100 km as the altitude of its emission. It is found that Chapman's mechanism can alone explain the observed characteristica of the λ5577 line. The diurnal variation of the intensity of this line has been attributed to the tidal oscillations in the upper atmosphere. On the other hand, irregular temporal and spatial variations of this line are caused by turbulence. The excitation of the λ6300 line is also considered. It is found that dissociative recombination of O 2 + ions with electrons lead to the production of the red oxygen line in the night airglow.