“…it, in its turn, is caused by the spatial and temporal distribution of the refractive index N. Therefore, the study of seasonal, diurnal and vertical distribution of N, making of its statistical model provides the great interest to predict the range of the radio systems for various applications, as well as estimates of the accuracy of measuring the coordinates of global navigation satellite systems (GNSS). Productive, at the same time may be the approach which was used earlier to describe the space-time non-stationary signals scattered underlying surfaces and "clear" sky using nested semi-Markov processes [1,2].…”