FOUNDATIONS OF THE PERSPECTIVE METHODOLOGY OF COMPLEX STUDIES OF THE INFLUENCE OF AURORAL CHARACTERISTICS OF THE POLAR IONOSPHERE ON THE CONDITIONS OF PROPAGATION OF TRANSPOLAR SIGNALS. REVIEW OF FOREIGN EXPERIMENTS AND RESULTS OF SOME MODELS
In the context of the article, the current state of research on the characteristics of the polar ionosphere is considered. The spectrum of the variety of scales of auroral structures that can occur on the path of signals in the ionosphere is illustrated by examples of auroral images and plasma characteristics obtained from different spacecraft orbits, from the Earth's surface and sounding rockets. Specific examples of the results of orbital, rocket and ground measurements of the characteristics of the polar ionosphere accompanying the generation of electron density irregularities and the scintillation of transpolar signals obtained by specific authors and groups of different laboratories in the polar regions of the ionosphere under various electrodynamic conditions are considered. Some results of modern models of generation of irregularities in the cusp and polar cap as the causes of scintillation of propagating signals are analyzed. Question: "Why does the generation of scintillations of GNSS signals occur when they "pierce" some auroral structures and does not arise when "piercing" others?" - remains. The answer to it is most likely associated with the conditions for the generation and development of plasma instabilities, leading to the formation of structures of plasma inhomogeneities with a scale from several centimeters to several tens of kilometers of different scales in different layers of the ionosphere, different MLT sectors of the polar ionosphere, and different IMF conditions. How, with the help of what diagnostic tools and with the help of what models, in what specific sets of conditions it is necessary to obtain and analyze information about the state of local areas of the environment - this is a problem, the solution of which will allow in the future to learn how to predict the propagation conditions of transpolar signals. Therefore, promising research requires a methodological basis for the development of technologies for setting up experiments aimed at both global and local complex observations of auroral structures, longitudinal and closing currents, characteristics of plasma inhomogeneities in different layers of the ionosphere, and their influence on the conditions of wave propagation at frequencies, used by orbital navigation and other systems.