Аннотация:The contributions of local and integral effects in radiosounding of the ionosphere from satellite are studied. It is shown that integral term as a rule is much larger than local one, that makes possible to perform radiotomography of the ionosphere and to reconstruct the electron density in the inhomogeneous ionosphere over large areas. A few examples of the ionosphere electron density reconstruction are given for different conditions. It is pointed out, that multiposition receiving system allows to separate the contributions of local and integral terms and also to estimate the effect on nonstationarity of the ionosphere with accuracy. (C) 1999 Elsevier Science Ltd. All rights reserved.