On the Ion Precipitation due to Field Line Curvature (FLC) and EMIC Wave Scattering and Their Subsequent Impact on Ionospheric Electrodynamics

Both field line curvature (FLC) and electromagnetic ion cyclotron (EMIC) wave scattering are believed to be associated with energetic ion precipitation, but their relative contributions to ionospheric ion precipitation and subsequent effects are still unclear. In this study, by using a kinetic ring current model, we investigate their impact on the ionosphere from two aspects: the global distribution of ion precipitation and resulting ionospheric conductance. Our results show that the intensity and coverage of ion precipitation due to EMIC waves are larger than that due to FLC scattering, while the latter mostly contributes to ion precipitation in outer regions (L > 4–5). We then estimate the conductance with empirical models using the simulated ion precipitation energy flux. When the EMIC wave associated proton precipitation is included, the conductance is significantly enhanced in the dusk‐to‐midnight sector and has a wide magnetic latitude (MLAT) range from around 52° to 62°, considerably altering the electric potential in the dusk sector, which further influences particle dynamics in the magnetosphere. On the contrary, the proton precipitation caused by FLC scattering only occurs at higher latitudes above MLAT = 60° and the corresponding conductance is slightly enhanced at midnight, with negligible influence on the convective electric potential. Although electron precipitation‐associated conductance is predominant globally, the results show that proton precipitation can also play an important role in ionospheric electrodynamics, especially when EMIC wave‐associated precipitating proton energy flux exceeds that of electrons in the dusk sector, a region where many subauroral coupling processes occur. Key Points Proton precipitation due to field line curvature (FLC) and electromagnetic ion cyclotron (EMIC) wave scattering is simulated and compared to electron precipitation FLC scattering causes proton precipitation at larger L shells, resulting in enhanced conductance at higher latitudes EMIC waves scatter protons in noon‐dusk‐midnight sector over wider MLATs, cause larger conductance and alter the ionospheric electrodynamics