Relations between classical and Sen-Wyller magneto-ionic theories in view of their application at checking of IRI electron density models

To estimate the possible error which can be caused by using the classical magnetoionic theory instead of the generalized Sen-Wyller theory (1960) in the calculation of radio wave propagation parameters and the derivation of electron density profiles from different radio wave experiments, model calculations were perforomed for different electron density profiles, frequencies, and latitudes. It is shown that the computation of radio propagation parameters, e.g., ionospheric absorption or reflection heights, can be carried out with either the generalized Sen-Wyller formula or the classical magnetoionic theory, if in this latter the effective collision frequencies are utilized; these can be estimated from the monoenergetic collision frequencies appearing in the Sen-Wyller formula. However, when using the classical theory, full wave calculations of LF and IF absorption may be in error of up to about 6 percent. For practical purposes, such as testing the IRI electron density model with radio propagation data, it is recommended that full wave calculations should be carried out with the generalized Sen-Wyller theory, whereas phase integral calculations could be performed with the classical theory.