Simulating the Ion Precipitation From the Inner Magnetosphere by H-Band and He-Band Electro Magnetic Ion Cyclotron Waves

Abstract During geomagnetic storms, magnetospheric wave activity drives the ion precipitation which can become an important source of energy flux into the ionosphere and strongly affect the dynamics of the magnetosphere-ionosphere coupling. In this study, we investigate the role of Electro Magnetic Ion Cyclotron (EMIC) waves in causing ion precipitation into the ionosphere using simulations from the RAM-SCBE model with and without EMIC waves included. The global distribution of H-band and He-band EMIC wave intensity in the model is based on three different EMIC wave models statistically derived from satellite measurements. Comparisons among the simulations and with observations suggest that the EMIC wave model based on recent Van Allen Probes observations is the best in reproducing the realistic ion precipitation into the ionosphere. Specifically, the maximum precipitating proton fluxes appear at L = 4–5 in the afternoon-to-night sector which is in good agreement with statistical results, and the temporal evolution of integrated proton energy fluxes at auroral latitudes is consistent with earlier studies of the stormtime precipitating proton energy fluxes and vary in close relation to the SYM-H index. Besides, the simulations with this wave model can account for the enhanced precipitation of < 20 keV proton energy fluxes at regions closer to Earth (L < 5) as measured by NOAA/POES satellites, and reproduce reasonably well the intensity of <30 keV proton energy fluxes measured by DMSP satellites. It is suggested that the inclusion of H-band EMIC waves improves the intensity of precipitation in the model leading to better agreement with the NOAA/POES data.