Kinetic model of the ring current-atmosphere interactions

Our numerical model of the ring current-atmosphere coupling (RAM) is further developed in order to include wave-particle interaction processes. The model calculates the time evolution of the phase space distribution function in the region from 2 R-E to 6.5 R-E, considering losses due to charge exchange, Coulomb collisions, and plasma wave scattering along ion drift paths. The spatial regions of ion cyclotron wave instability are determined by calculating the convective growth rates for electromagnetic ion cyclotron (EMIC) waves, integrating them along wave paths, and selecting regions of maximum wave amplification The source regions are located on the duskside in agreement with the predominant occurrence of EMIC waves. A spectral power density of 1 nT(2)/Hz is adopted within the unstable regions. According to quasi-linear theory, the fluctuating fields are regarded as imposed on the system, and the losses due to wave-particle interactions are described with diffusive processes. The effects of the presence of heavy ion components on the quasi-linear diffusion coefficients are also considered. Resonance with ion cyclotron waves reduce the anisotropy of the proton population and the unstable regions disappear with time. Global patterns of precipitating ion fluxes are obtained and compared with observations.