  Low energy galactic cosmic rays as well as particles accelerated to high
energies either at the solar surface or in the interplanetary medium have
access to the atmosphere above a given position on the Earth depending upon the
state of the magnetosphere. The interpretation of the cosmic ray anisotropy,
deduced from the neutron monitor (NM) network, must assume the variability of
the magnetospheric configuration. Along with a short review of changes of the
geomagnetic cutoffs in the disturbed magnetosphere reported in the earlier
papers, we present the results of computations of transmissivity function and
asymptotic directions for selected points on the ground and for a low altitude
polar orbiting satellite as well. The computations, based on different
available models of geomagnetic field of external sources are performed for
quiet time periods and for strong geomagnetic disturbances occurred in 2003 and
2004.
