Observations of Particle Loss due to Injection-Associated EMIC Waves

We report on observations of electromagnetic ion cyclotron (EMIC) waves and their interactions with injected particles in the ring current system and high energy radiation belt electrons. The magnetic field experiment (Electric and Magnetic Field Instrument Suite and Integrated Science or EMFISIS) onboard the twin Van Allen Probes spacecraft measured EMIC waves near L = 4-6. Particle data from the Radiation Belt Storm Probe Ion Composition Experiment (RBSPICE) and t he Helium Oxygen Proton Electron (HOPE) plasma spectrometer on the spacecraft show that the waves were associated with a particle injection. The injection provided energy to increase ion temperature anisotropy and thus generate or enhance EMIC wave activity. The phase space density (PSD) profiles from electron data from the Relativistic Electron Proton Telescope (REPT) show localized minima in electron fluxes at the highest energies during and after the EMIC wave activity, which suggests EMIC wave-induced ultrarelativistic electron loss. In addition, the Space Environment Monitor (SEM) onboard NOAA's Polar Orbiting Environmental Satellites (POES) observed particle precipitation associated with the EMIC waves near the footprint of the Van Allen Probes spacecraft.