  We present results from Lyon-Fedder-Mobarry (LFM) global, three-dimensional
magnetohydrodynamic (MHD) simulations of the solar wind-magnetosphere
interaction. We use these simulations to investigate the role that solar wind
dynamic pressure fluctuations play in the generation of magnetospheric
ultra-low frequency (ULF) pulsations. The simulations presented in this study
are driven with idealized solar wind input conditions. In four of the
simulations, we introduce monochromatic ULF fluctuations in the upstream solar
wind dynamic pressure. In the fifth simulation, we introduce a continuum of ULF
frequencies in the upstream solar wind dynamic pressure fluctuations. In this
numerical experiment, the idealized nature of the solar wind driving conditions
allows us to study the magnetospheric response to only a fluctuating upstream
dynamic pressure, while holding all other solar wind driving parameters
constant. The simulation results suggest that ULF fluctuations in the solar
wind dynamic pressure can drive magnetospheric ULF pulsations in the electric
and magnetic fields on the dayside. Moreover, the simulation results suggest
that when the driving frequency of the solar wind dynamic pressure fluctuations
matches one of the natural frequencies of the magnetosphere, magnetospheric
cavity modes can be energized.
