Nonlinear plasma density modification by the ponderomotive force of ULF   pulsations at the dayside magnetosphere
  We investigate analytically and numerically a nonlinear modification of the magnetospheric plasma density under the action of the ponderomotive force induced by ULF traveling waves, using the nonlinear stationary force balance equation. This equation is applied to both the dipole and dayside magnetosphere having one and two minima of the geomagnetic field near the magnetospheric boundary. The separate and joint actions of the ponderomotive, centrifugal, and gravitational forces on the density distribution are shown. 
A. K. Nekrasov and F. Z. Feygin
astro-ph.EP