REFRACTION DISTORTIONS OF TRANSIONOSPHERIC RADIO SIGNALS CAUSED BY CHANGES IN A REGULAR IONOSPHERE AND BY TRAVELING IONOSPHERIC DISTURBANCES

This paper generalizes experimental data on variations of the angles of arrival of transionospheric radio signals caused by changes in a regular ionosphere and by effects of medium-scale travelling ionospheric disturbances (TIDs). The data are based on radio astronomical observations of discrete sources and compact active features on the Sun as well as on angular measurements of signals from artificial Earth satellites with geostationary and circular orbits. The experimental data are interpreted through calculations of refraction corrections using a Gaussian model of a regular ionosphere disturbed by a three-dimensional travelling wave (the TID model) as well as an adaptive model of a regular ionosphere. Some possibilities of correcting refraction distortions with the use of appropriate models and ionospheric diagnostic tools are discussed.