Propagation of sudden impulses in the magnetosphere: Linear waves

Abstract

The magnetosphere is often perturbed by impulsive input such as interplanetary shocks and solar wind discontinuities. We examine how these initial perturbations are propagating within the magnetosphere over various latitude regions by investigating the wave propagation on a meridional plane in a time-dependent manner. The three-dimensional dipole model is used to represent the plasmasphere and magnetosphere with a realistic Alfven speed profile. Effects of refraction, which result from magnetic field curvature and inhomogeneous Alfven speed, are found to become important near the plasmapause. The numerical results show that, when the disturbances are assumed at the subsolar point of the dayside magnetosphere, the travel time becomes smaller to the polar ionosphere compared to the equatorial ionosphere.