Statistical Radio Tomography of a Randomly Inhomogeneous Ionosphere

Abstract

Very often the ionosphere contains large volumes filled with a great number of electron density irregularities of different sizes. This is typical of equatorial and polar regions, especially in the nighttime. Of course, in such cases, reconstruction of separate realizations of the disturbed dynamic ionosphere makes little sense, and of more interest is reconstruction of the statistical parameters of a turbulent randomly inhomogeneous ionosphere, such as the correlation function or the spectrum of electron density fluctuations. The statistical approach is explicitly informative of the structure of a disturbed ionosphere. It allows studying generation mechanisms of the irregularities and their effect on propagating radio signals. A randomly inhomogeneous ionospheric plasma causes fluctuations or scintillations in the radio waves coming through the ionosphere. Getting rid of such scintillations is a problem of greatest importance in radio location and communication systems. Separation in time and space of the receiving systems and signal coding schemes helps to weaken the influence of scintillations, but design of such schemes requires information about the statistical parameters of electron density irregularities.