Abstract
There are many Pi pulsations in magnetosphere. We think that the magnetospheric cavity resonance process is affected by the change in the Alfven speed distribution. We carry out the numerical calculation to make sure our ideas in one dimensional model. We calculate the frequency of the wave in magnetosphere in some cae of the magnetopause perturbations. And we concluded that many conditions of the magnetosphere and the situations of the perturbations give the influence to the Pc waves.
