Inclusion of Nonresonant Effects Into Quasi-Linear Diffusion Rates for Electron Scattering by Electromagnetic Ion Cyclotron Waves

Electromagnetic ion cyclotron (EMIC) waves are a key plasma mode affecting radiation belt dynamics. These waves are important for relativistic electron losses through scattering and precipitation into Earth's ionosphere. Although theoretical models of such resonant scattering predict a low-energy cut-off of similar to 1 MeV for precipitating electrons, observations from low-altitude spacecraft often show simultaneous relativistic and sub-relativistic electron precipitation associated with EMIC waves. Recently, nonresonant electron scattering by EMIC waves has been proposed as a possible solution to the above discrepancy. We employ this model and a large database of EMIC waves to develop a universal treatment of electron interactions with EMIC waves, including nonresonant effects. We use the Green's function approach to generalize EMIC diffusion rates foregoing the need to modify existing codes or recompute empirical wave databases. Comparison with observations from the electron losses and fields investigation mission demonstrates the efficacy of the proposed method for explaining sub-relativistic electron losses by EMIC waves. Precipitation of energetic electrons from the equatorial magnetosphere to the Earth's ionosphere plays a crucial role in the dynamics of the radiation belt and ionosphere ionization. Such precipitation is primarily driven by wave-particle interactions. However, accurately modeling these interactions requires precise knowledge of the electron energy ranges which is affected by different wave modes present in the equatorial magnetosphere. A notable challenge arises from the contradiction between model-predicted energy ranges of electron precipitation by electromagnetic ion cyclotron (EMIC) waves and the energies observed by spacecraft during such precipitation events. By combining a new theoretical approach with detailed observational data sets of these waves, we successfully resolved this contradiction, offering a powerful tool for the simulation of electron precipitation driven by EMIC waves. We provide a statistical model of nonresonant electron scattering by electromagnetic ion cyclotron waves We show the main wave and electron parametric regions where nonresonant effects can be important for electron precipitation We derive an analytical approximation allowing generalization of the quasi-linear diffusion rates including nonresonant effects