Resonant Scattering by Excited Gaseous Components as an Indicator of Ionization Processes in the Atmosphere

Abstract

The results of lidar sensing of the atmosphere at altitudes in the range of 25–600 km from the Kamchatka Lidar Station (53° N, 158° E) obtained in 2008–2022 are presented. The results of an analysis of the data of two-frequency lidar sensing of the thermosphere are given. The increased scattering at wavelengths of 532 and 561 nm is due to resonant scattering by excited atomic nitrogen and oxygen ions. Manifestations of resonant scattering in the middle atmosphere are also discussed. It is demonstrated that these ions are excited during the process of the ionization of the main atmospheric species by the precipitation of energetic electrons. The findings show that, during lidar soundings of the middle atmosphere, the ionization process can form imaginary aerosol formations. The spectrum of precipitating electrons can be estimated from the shape and position of the maximum of the lidar signal profile. It is shown that the process of the excitation of ions in the ground state does not play any significant role in the formation of the backscattered lidar signal. The signal does not carry information about the content and height profile of ions at the ground state. The appearance of resonant scattering in the atmosphere indicates the presence of the ionization sources.