New theoretical aspects of the shape of the magnetospheric boundary

On the basis of the magnetopause model developed by Beard and Mead, the dependence of the shape and geometry of the magnetopause, and especially the position of the neutral points, on several effects not included in the old model have been investigated. The approximation that all particles are incident parallel to the Earth-Sun line has been dropped, and an angular distribution for the solar wind particles introduced, with the intention of taking into account the turbulence of the plasma in the magnetosheath. Under the same assumptions, the effects of various tilt angles of the dipole with respect to the Earth-Sun direction are considered. The alterations caused by a purely southward or northward directed interplanetary magnetic field are calculated and the influence of the magnetic field of the current sheet is analysed. For each of these cases, the pressure-balance equation is given which expresses the equilibrium between kinetic particle and magnetic field pressures. The numerical results for the noon-midnight meridional plane are presented and compared with satellite observations. (Auth.)