Reconstruction of the Parameters of the Lower Ionosphere at Night Using VLF Radiophysical Data

Abstract Electromagnetic radiation of the very low frequency (VLF) band is an effective tool for remote sensing of ionospheric disturbances in D layer of ionosphere. Analysis of variations in the amplitude and phase of a radio signal during solar X‐ray flares allows us to reconstruct the parameters of the lower ionosphere with some assumptions. In this paper, the possibility of using a two‐frequency VLF path to reconstruct the altitude profile of the electron concentration of not only the daytime but also the nighttime ionosphere was demonstrated for the first time. The presented approach opens up the possibility of monitoring the state and dynamics of the lower ionosphere during daytime and nighttime periods along the propagation paths of VLF radio signals and predicting the operating conditions of the corresponding radio engineering systems operating in the VLF band.