THE SPATIAL STRUCTURE OF POLOIDAL ALFVEN OSCILLATIONS OF AN AXISYMMETRICAL MAGNETOSPHERE

Based on equations of ideal magnetohydrodynamics a theoretical study is made of the spatial structure of poloidal Alfvén oscillations of the axisymmetric magnetosphere with large but finite values of azimuthal wave number m. The study has revealed a transverse dispersion of such oscillations which is attributable to the curvature of geomagnetic field lines that determines the fine transverse structure of the oscillation field. Solutions for different cases of the behaviour of magnetospheric parameters are obtained. By taking the summation over harmonics with different m, we have constructed a solution localized in both transverse coordinates which may be treated as the oscillation of a thin flux tube. © 1990.