Initial responses of magnetospheric plasma flows to the dynamic pressure enhancements

Using the solar wind data obtained from OMNI web, we find 1778 dynamic pressure enhancement events during Mar 2007 to Dec 2012. Then we check the responses of Magnetospheric plasma flows to these events and find 64 responses show clear sudden impulse (SI) signatures from THEMIS observations. We superpose the initial responses of the flows in one plot to find two flow vortices exist at two sides of the near earth magnetotail respectively, which was not observed in-situ before. There are some ULF wave observations after initial responses.