@article{oai:nagoya.repo.nii.ac.jp:00020106, author = {Yumoto, Kiyohumi and Watanabe, Shigeto and Oya, Hiroshi}, journal = {Proceedings of the Research Institute of Atmospherics, Nagoya University}, month = {Mar}, note = {We have developed a simple MHD computer code that simulates transient responses of a "box" magnetosphere, having inhomogeneties of Alfvén speed distribution in the radial direction, with respect to poloidal magnetopause perturbations of a variable initial wave form. An impulsive magnetopause perturbation with a small azimuthal wave number and a broad-band frequency under quiet geomagnetic condition, is confirmed to stimulate the magnetospheric cavity resonance composed of different harmonics which further ouple into the toroidal Alfvén resonances, where the eigen periods match those of the cavity harmonic waves. Another impulsive magnetopause perturbation, having a larger azimuthal wave number and a lower band frequency under disturbed geomagnetic condition, can excite a transient Alfvén resonance oscillation in the outer magnetosphere, of which amplitude and period decrease with increasing the distance from the magnetopause. The frequency range and azimuthal wave number of the initial magnetopause perturbations and the plasmapause position associated with the geomagnetic activity are found to be key parameters, controlling which of the localized toroidal Alfvén, the transient Alfvén, and the magnetospheric cavity resonances is predominantly stimulated in the model magnetosphere. The change in the Alfvén speed distribution plays more important role and dominates the magnetospheric cavity resonance process.}, pages = {17--36}, title = {MHD RESPONSES OF A MODEL MAGNETOSPHERE TO MAGNETOPAUSE PERTURBATIONS}, volume = {37}, year = {1990} }