Ionospheric responses modulated by quasi-periodic EMIC waves associated with ULF waves

Energetic protons can be efficiently scattered by electromagnetic ion cyclotron (EMIC) waves into the upper atmosphere. This process represents a crucial mechanism for the exchange of energy and particles between the magnetosphere and ionosphere. In this study, quasi-periodic EMIC waves induced by Pc4 ULF waves were observed by the Van Allen Probes (RBSP) B satellite during a magnetic storm event on September 8, 2017. The associated pitch angle diffusion coefficient