  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.
