Excitation of the Plasmapause at Ultralow Frequencies

Abstract
Observational evidence and the theoretical interpretation indicate that magnetic disturbances exterior to the plasmasphere boundary (within the magnetosphere) can excite damped, sinusoidal oscillations, which can be inferred as a magnetohydrodynamic surface eigenmode, at the plasmapause. The wave frequency and damping rate can be used to infer the plasma density inside the plasmapause and the plasma density gradient at the plasmapause.