Coordinated observations on board GEOS 2 of energetic particles (20 to 400 keV), plasma particles (300 eV to 20 keV), dc electric fields, and ULF waves (0.2 to 10 Hz) at the geostationary orbit reveal several occasions on which sharp increases in particle flux occurred near 1400 LT without any appreciable energy dispersion for ions at 90 ¿Z pitch angle. The intensity increases of ions with pitch angles away from 90¿ preceded those at 90¿ and showed clear energy dispersion that is consistent with the idea that these particles are injected in the midnight sector and drift toward noon. The global electric field establishes boundaries that particles of given adiabatic invariants cannot penetrate. A change or reversal of the electric field moves these boundaries so as to permit their observation at GEOS 2. Such boundaries seem to be associated with intense ULF waves observed close to the proton gyrofrequency and its harmonics. The waves may be compressional drift waves destabilized by plasma pressure gradients.