Characteristics of dayside magnetospheric flows during solar wind dynamic pressure pulse

The response scenario of dayside magnetospheric plasma flows to the sudden increase of solar wind dynamic pressures was studied with 5 events from THEMIS observation. In all events we observed bipolar Vx(-/+) signatures as a response. The inferred flow vortices presented to be rotating clockwise and counterclockwise in the morning and afternoon side, respectively, as see from the north. Moreover, the pre and after noon flow vortices move toward -y and +y direction. The in situ observation of dayside plasmasheet flow vortices may provide a new possible mechanism for the solar wind dynamic impulse associated dayside ionospheric convection vortices.