We show in this paper that intermediate shocks are formed from ki-netic Alfven waves through wave form continuous steepening. From the action of nonlinear interaction and dispersion Alfven solitons are formed and then evolve into shocks. We calculated the traveling stationary struc-tures directly from nonlinear autonomous equations which we had derived. These traveling stationary structures correspond to intermediate shock, switch-on shock or Alfven solitary waves. Another kind of rare discontinuity was discovered in the calculation from the rarefying solitary waves. The solitary wave series remain on the front of the shocks because of no strong dissipation appears in the equation. When we added some anomalous dissipation terms to the equations, intermediate shocks with increased in entropy appeared.

We present the temporal evolution of magnetic field topology in the magnetotail with a southward IMF in order to identify the magnetic reconnection. The magnetic field topology is uniquely determined by the eigenvalues of the critical points, if they are not degenerated. This is because the critical points, their number, and the rules between them characterize the whole magnetic field pattern. At the critical points, the magnetics become zero. The magnetic vector field curves and surfaces are both integrated out along the principal directions of certain classes of critical points including the Earth’s dipole magnetic field. The skeleton that includes the critical points, characteristic curves, and surfaces provides the three-dimensional topological structure of the reconnection. The change of the skeleton, i.e. the change of the topology, has revealed the occurrence of magnetic reconnection. Namely, threedimensional "X-points" or the more-than-two critical points that are saddle and connected each other are unstable and can move, vanish, and generated.

Magnetic reconnection at the high-latitude magnetopause is studied using 2.5-dimensional Hall-MHD simulation. Concentric flow vortices and magnetic islands appear when both Hall effect and sheared flow are considered. Plasma mixing across the magnetopause occurs in the presence of the flow vortices. Reconnected structure generated in the vicinity of the subsolar point changes its geometry with increasing flow shear while moving to high latitudes. In the presence of flow shear, with the Hall-MHD reconnection a higher reconnection rate than with the traditional MHD is obtained. The out-of-plane components of flow and magnetic field produced by the Hall current are redistributed under the action of the flow shear, which makes the plasma transport across the boundaries more complicated. The simulation results provide some help in understanding the dynamic processes at the high latitude magnetopause.

Using the observations of LASCO aboard SOHO in the interval from Mar. 1997 to Dec. 2003, 302 earth-directed halo CMEs are selected and the source regions are located in MDI synoptic charts. A statistical analysis has been made with the emphasis on the CMEs' largescale source regions as well as the correlation between CMEs and solar surface activity. The statistics show that CMEs are intrinsically related to surface activity. Four groups of CMEs' large-scale source structures are identied on the photosphere. They are: Ⅰ, Extended bipole regions (EBRs) with long magnetic neutral line; Ⅱ, Closely packed active regions (ARs); Ⅲ, Large-scale magneticux of the same polarity runs through the opposite hemisphere, along the boundary there appears transequatorial laments; Ⅳ, Between two EBRs with long lament. The result shows that CME-associated source activity is closely related to the types of large-scale magnetic structures.