We present EUV observations of the plasmasphere from 1938 to 2211 UT on 28 June 2000 characterized by the presence of bifurcated radial enhancements of the He+ plasma distribution in the nightside sector. These features remain stable throughout the period of observation and are found to move about the Earth at 67% of the corotation rate. Two-dimensional simulation of the plasmasphere assuming the presence of an azimuthal standing wave patterns at L = 1.8 and 2.5 suggests that the organization of the outer plasmasphere is the result of convective motion driven by a ULF standing wave. Preliminary analysis of ground-based magnetometer data provided by the IMAGE magnetometer network during the period of EUV observation indicates the presence of several narrow-frequency oscillations extending down to 0.68 mHz, consistent with simulation results. Similar narrow-frequency features are found in preliminary analysis of ACE Solar Wind Electron Proton Alpha Monitor (SWEPAM) bulk solar wind velocity data. We speculate that the observed radial He+ enhancements of the nightside plasmasphere may be the result of a nonresonant oscillation driven by the solar wind.