Solar Wind Driving of the Storm-Time Ring Current

We use ring current observations, along with MHD simulation results, to investigate the magnetospheric response to different types of solar wind energy input. The MHD simulations show that the dissipation of energy in the magnetosphere-ionosphere system is very sensitive to solar wind density variations during time of strong driving, with large density pulses during southward Bz exhibiting significantly greater geoeffectiveness than strong Bz without such pulses. This suggests that solar wind kinetic energy flux may play a significant role during southward Bz. We compare this behavior with the behavior of ring current ions (using particle measurements and Dst) and show that ring current ions exhibit a similar response to different types of solar wind energy coupling. We present observations showing the overall magnetospheric effect of these different solar wind drivers. We also pay particular attention to the type of solar wind drivers at work, whether high speed streams, coronal mass ejections, etc., to determine whether this difference has a significant effect on energy coupling into the magnetosphere.