Response of geosynchronous magnetic field z component and geomagnetic field to solar wind dynamic pressure change

In this paper, we study 123 solar wind dynamic pressure change events, not including interplanetary shocks, with statistical methods. The results indicate that the geosynchronous magnetic field z component presents strong positive response to solar wind dynamic pressure changes near the noon meridian. The amplitude of geosynchronous magnetic field response shows an obvious magnetic local time distribution in our analysis. The largest amplitude of geosynchronous magnetic field z component response to solar wind dynamic pressure increase events is found at the pre-noon region, and that to decrease events is found at post noon region. On the dayside, the amplitude of geosynchronous magnetic field z component has the best correlation with the square root of the solar wind dynamic pressure, especially near the sunspot region. To the same solar wind dynamic pressure changes, the response on the dayside is significantly stronger than that on the night-side, with distinguished magnetic local time distribution. The dependence between geomagnetic indices SYM-H response amplitude and the square root of the solar wind dynamic pressure is very distinct, especially when magnetosphere is strongly compressed. The amplitude of sudden impulses (dSYM-H) correlates better with the amplitude of magnetic field at geosynchronous orbit near the sub-solar region, which declines in the region of dawn and dusk, especially weakens near the midnight region.