Evolution of techniques for electron-density profile analysis of ionograms attests to a close coupling with ionospheric modelling. Advanced achievements in both fields are used in the International Reference Ionosphere, IRI, the selection being made by criteria of internal consistency. This paper presents the results of comparisons of modern methods of calculating electron-density profiles from ground-based vertical-incidence ionograms. It is shown that the shapes of the resulting electron-density profiles depend upon the peak height and electron density of the E and F-layers. Formulae for the F2-layer sub-peak electron density, the E-F valley and their relation to the peak height of the ionosphere are presented as functions of solar-zenith angle. Implementation of such relationships allows refinement and considerable simplification of representations in the IRI, depending on the solar and geophysical controlling parameters. © 1987.
Gulyaeva, T. L. (1987). Progress in ionospheric informatics based on electron-density profile analysis of ionograms. Advances in Space Research, 7(6), 39–48. https://doi.org/10.1016/0273-1177(87)90269-9