Formation of Resonant Scattering on Excited Ions of Oxygen and Nitrogen Atoms in Lidar Studies of the Atmosphere

The results of the analysis of lidar data obtained in Kamchatka (53° N, 158° E) in 2008–2022 are presented. Atmospheric sounding was carried out in the altitude range of 25–600 km at wavelengths of 532 and 561 nm. The appearance of increased scattering in the altitude range of 200–400 km was detected. It is shown that it is caused by resonant scattering on excited ions of nitrogen and oxygen atoms. Under night conditions, such ions are created in the process of ionization of the main gas components of the atmosphere during the precipitation of energetic electrons. It is shown that the process of excitation of ions in the ground state does not play any significant role in the formation of the lidar signal. Resonant scattering at these altitudes appears in the process of ionization of the main gas components—N2, O2, and O. A mechanism for the formation of a lidar signal of resonant scattering on excited ions is proposed. A general scheme is proposed for assessing the potential efficiency of laser radiation when choosing a wavelength for lidar research of the atmosphere. The meaning of the scattering coefficient in the thermosphere is discussed.