The structure of one-dimensional standing MHD waves in, and at the boundary of, the dayside plasmasphere

Possibilities are demonstrated for finding the basic frequency of eigen-oscillations for various types of wave resonators by means of the amplitude and phase fluctuation correlation functions (APCF) method. The APCF method is based on the fact that in the isotropic resonators with arbitrary parametres of medium the interval between two neighbouring peaks of correlation functions of the oscillations in question is only determined by the first harmonic frequency of one of possible one-dimensional standing waves. In this work the APCF method is used for the first time for processing the real records of geomagnetic disturbances. For the oscillations recorded at “Borok” and “Mondy” geomagnetic observatories, the periods of the first harmonics of standing waves in the magnetospheric resonator were obtained. It was found that all typical magnitudes of these periods correspond to known modes of MHD oscillations in the plasmasphere and at its boundary.