Wave mechanism of the magnetospheric convection

The problem of momentum transfer from the solar wind to the geotail via magnetosonic waves has been solved. The structure of the wave field of monochromatic MHD oscillations is calculated in a cylindrical model of the geotail with a background plasma distribution typical of the geotail lobes. Fast magnetosonic waves entering the magnetosphere from the magnetosheath excite slow magnetosonic waves at the resonance magnetic shells inside the geotail. Resonant oscillations interact with the background plasma transferring their momentum to it. The problem of modifying the ion distribution function of the background plasma for a given spectrum of magnetosonic oscillations in the magnetosheath has been solved in the quasilinear approximation. It is shown that, in the process, ions in the geotail lobes acquire an average Earthward velocity. The region of the most effective transfer of the momentum is near the magnetopause, in the area of open field lines, housing resonance shells for slow magnetosonic oscillations of a broad range of frequencies and wave numbers. The wave transfer mechanism for the momentum is capable of generating an Earthward flow of magnetospheric convection during prolonged periods of the Northern IMF component.