Geoefficiency of solar wind discontinuities

We have investigated the solar wind–magnetosphere coupling efficiency in response to solar wind dynamic pressure enhancements. We investigate fast forward shocks, corotating interaction regions (CIRs), and pressure pulses separately, by conducting a statistical driver-response analysis. We complement the observations by results from the GUMICS-4 global magnetohydrodynamic (MHD) simulation, which in all cases is in good agreement with the observational results. Analysis of shock propagation inside the magnetosphere shows that the events with higher speed are associated with higher ionospheric activity. The coupling efficiency depends on the disturbance characteristics: it is higher for small solar wind Ey and smaller for high Ey. The coupling efficiency is highest for small values of IMF Bz and increases with increasing solar wind speed. These results confirm that pressure changes drive dynamic changes in the ionosphere independent of the changes associated with the driving reconnection electric field.