This paper overviews some recent studies of spatio-temporal structure of poloidal (high-m) Alfvйn waves (Pc4—5) in the magnetosphere, with taking into account finite field line curvature and plasma pressure. The effects of finite pressure plasma are especially essential near the magnetospheric equator, where an opaque region for Alfvйn waves can be formed. This region is bounded by two turning points which restrain penetration of the wave energy far from the ionosphere, and an Alfvйn resonator appears on a part of the field line adjacent to the ionosphere. Due to this effect the ULF pulsations in the Northern and Southern hemispheres can be nonconjugated. Another result is a peculiar field-aligned structure of the wave magnetic field: its fundamental harmonic must have three nodes, rather than one node as with cold plasma. The transverse structure of the wave is determined by the excitation mechanism. It is supposed in the report that wave is emitted by an alternating current created by the drifting particle cloud or ring current inhomogeneity. It is shown that the wave appears in some azimuthal location simultaneously with the particle cloud arrival at the same spot. The wave propagate westward, in the direction of the proton drift. The expected properties of the wave (amplitude, polarization, hodogram) are close to the observed properties of poloidal ULF pulsations.
