Relation Between Actual and Virtual Ionospheric Height

Abstract

Translation of virtual height of the ionosphere into actual height is achieved by fitting a parabolic maximum of electron density to observations of variation of virtual height with wave frequency. Methods for measuring the thickness of a region and the height of maximum electron density are described and applied. The simplest measure of the actual height of maximum electron density is the virtual height at five-sixths of the penetration frequency. This measure is found to be remarkably reliable for $F$ region at night. During the daytime it is often necessary to correct ${F}_{1}$ observations for presence of $E$ region, and ${F}_{2}$ observations for presence of ${F}_{1}$ region. A simple technique of correction is described and applied. The disadvantages of minimum virtual height for quantitative study of diurnal variation of ionospheric height are emphasized.