Solar wind dynamic pressure variations: Quantifying the statistical magnetospheric response

Abstract

Solar wind dynamic pressure variations are common and have large amplitudes. Existing models for the transient magnetospheric and ionospheric response to the solar wind dynamic pressure variation are quantified. The variations drive large amplitude (approx 1 R sub E) magnetopause motion with velocities of approx. 60 km/s and transient dayside ionospheric flows of 2 km/s which are organized into double convection vortices. Ground magnetometer signatures are more pronounced under the auroral ionosphere, where they reach 60 to 300 nT, and under the equatorial electrojet. A statistical comparison of transient ground magnetometer events seen at a South Pole station and geosynchronous orbit indicates that all but the weakest ground events are associated with clear compressional signatures at the dayside geosynchronous orbit.