Penetration of Plasmapause Surface Waves Into the Plasmaspheric Plume

Plasmapause surface waves (PSWs) and plasmaspheric plumes are two crucial phenomena of magnetosphere-ionosphere coupling system in response to geomagnetic disturbances. However, it remains elusive what the potential interaction exists between them. In this letter, we identify the penetration of PSWs into the plasmaspheric plume and their interaction with each other. After the PSWs penetrating into the plume structure, they can oscillate the plume and cause the periodical scattering and precipitation of thermal particles. Meanwhile, the foundational frequency of PSWs in the plume becomes lower, and the higher-harmonic frequencies of PSWs are simultaneously observed. Their corresponding energy of modulated and precipitating particles also reduces to <210 eV, which is different from the <1 keV electrons and <50 keV ions in those ordinary PSWs occurring near the main plasmapause. Our results advance our understanding of the complex interplay effect among various dynamic structures in the dusk inner-magnetosphere and aurora region.