A semi-empirical approximate method for studying some issues of aeronomy of the ionospheric D-region. III. Detailed analysis of the photochemistry of the environment under conditions of increased ionization

Using the previously proposed semi-empirical method (Kozlov et al., 2022; Kozlov, Nikolaishvili, 2024), which is a fairly simple mathematical model (a system of five algebraic equations for calculating the concentrations of primary and cluster positive ions, primary and complex negative ions, as well as the electron density), we have calculated the ionospheric parameters that determine the behavior of the D-region under conditions of increased ionization (Solar Proton Events (SPE) on November 2–5, 1969, and the High-altitude Nuclear Explosion (HNE) conducted in 1962). Detailed analysis of the obtained parameter values has shown that the calculation results do not contradict the generally accepted photochemical mechanisms occurring under the SPE and HNE conditions considered. We identified the main trends in the changes of these parameters. A conclusion is made about the possibility of using the semi-empirical method in various heliogeophysical conditions and the need to develop a model for the transitional time of day (morning and evening twilight), and some possible directions for further research are outlined.