IMPULSIVE PULSATION EVENTS AND PULSATION BEATS

Twenty-three pulsation events from 11 stations in Central and Northern Europe, and from two satellites, were surveyed for Impulsive Pulsatio n Events (IPEs) and for pulsation beats. IPEs generally had activity p eaks at the same period at all stations studied, even if the spectrum of the background had latitude-dependent periods. From pulsation beats , the width of the coherent shells of field lines could be deduced; th ey were in coincidence with values obtained by other methods. As a con clusion, the existence (and sometimes coexistence) of slightly transfo rmed upstream waves and shell resonances in the magnetosphere is confi rmed.