The preliminary results of the investigation of the relation between F-scattering and pearl-type pulsations are presented. The data used here for the scattering and short-period pulsations (SPP) were taken from tellurograms and ionograms which were obtained in the laboratories of the Siberian Institute of Terrestrial Magnetism, the Ionosphere and the Propagation of Radio Waves associated with the Academy of Sciences of the USSR (SibIZMIR SO AN SSSR) during the period of the vernal equinox from 1959 through 1963. Basically an amplitude-frequency analysis was carried out. The results of the studies are presented in the form of tables and graphs. A comparison is given of the intensities and duration of the phenomena being investigated. (Author).

The subject of geomagnetic micropulsations has developed extremely rapidly and it is difficult to know when is an appropriate time to pause and assess the sum total of our knowledge-both observational and theoretical. There has in recent years been a tremendous increase in both the quantity and quality of data and also many theoretical ad vances in our understanding of the phenomenon. Undoubtedly there will be further progress in both areas but it seems worthwhile now to review both our knowledge and our ignorance. This book was essen tially completed by the end of April 1969 and tries to give a summary of the subject up to that time. The Earth is enclosed in the magnetosphere, a hollow carved out of the solar wind by the Earth's magnetic field. Above the ionosphere there is a very tenuous thermal plasma of partially ionized hydrogen in diffusive equilibrium with magnetic and gravitational forces, and ener getic protons and electrons that constitute the trapped Van Allen ra diation belts. Throughout this anisotropic and inhomogeneous plasma, natural and man-made electromagnetic energy propagates in a wide variety of modes and frequency bands. This book is concerned with that class of natural signals called geomagnetic micropulsations-short period (usually of the order of seconds or minutes) fluctuations of the Earth's magnetic field.