Effects of polarization-reversed EMIC waves on the ring current dynamics

Abstract

Listen

Translate article

It is widely believed that the electromagnetic ion cyclotron (EMIC) waves play an important role in influencing the radiation belt and ring current dynamics. Most studies investigated the effects or characteristics of EMIC waves assuming their left-handed polarization. However, recent studies found that the polarization reversal, which occurs at higher latitudes along the wave propagation path, can change the wave-induced pitch angle diffusion coefficients. Whether such a polarization reversal can influence the global ring current dynamics remains unknown. In this study, we investigate the ring current dynamics and proton precipitation loss in association with the polarization reversed EMIC waves using the Ring current - Atmosphere interactions Model (RAM). The results indicate that the polarization reversal of H-Band EMIC waves truly can decrease the scattering rates of protons of 10 to 50 keV or > 100 keV by comparing with the scenario where the EMIC waves are considered as purely left-handed polarized. Additionally, it is found that the global ring current intensity and proton precipitation can be slightly affected by the polarization reversal, especially during the prestorm and recovery phase, but the effects are not that large during the main phase. This is probably because the H-Band EMIC waves contribute to the proton scattering loss primarily at E < 10 keV, an energy range that is not strongly affected by the polarization reversal.