Research of Geospace Magnetic Field Response to the Solar Wind Disturbances

The goespace magnetic field response to the solar wind disturbances including interplanetary shocks, solar wind dynamic pressure increase and decrease is analyzed comparatively. The geosynchronous magnetic field has positive response to all the disturbances strongly near the noon meridian, and has positive response in the nightside of the magnetosphere weakly. However negative responses were sometimes observed in the nightside. From our results, the geomagnetic index SYM-H always shows positive response to the disturbances of solar wind. The amplitude of geosynchronous response d Bz could be determined by the square root of the solar wind dynamic pressure near the noon meridian with good correlation the same as the geomagnetic indices. The d Bz at the geosynchronous orbit near local noon and the amplitude of sudden impulses (dSYM-H) on the ground are highly correlated under the circumstances action of IP shock or solar wind dynamic pressure increase, differentiating from the dynamic pressure decrease distinctly. It is shown that the IP shocks have some commonness with the solar wind dynamic pressure increase in affecting on the geospace magnetic field.