The dynamics of Subauroral Polarization Streams (SAPS) is an outstanding magnetosphere-ionosphere coupling problem associated with the electrodynamics at the interface between the hot and cold particle populations in the inner magnetosphere. Although SAPS have been studied for over three decades, their generation/evolution during geomagnetic active times, in particular substorms, are still not well understood. In addition, wave-like oscillations embedded within SAPS have been reported. However, they are neither well characterized nor understood, and the geomagnetic disturbance conditions for these wave-like activities have not been established. Moreover, the effects of SAPS on the global ionosphere-thermosphere system have not been extensively studied. Ground-based observations, such as those from Super Dual Auroral Radar Network (SuperDARN) and all-sky imager arrays, and space-based measurements, such as those from the Time History of Events and Macro-scale Interactions during Substorms (THEMIS) and the Van Allen probes, as well as the Global Ionosphere Thermosphere Model (GITM) are used to carry out an integrated study of the dynamics of SAPS and their effects on the coupled IT system. [Zou et al., 2009b, Zou et al., 2012, Yu et al., 2015, Wang et al., 2019, Aa et al., 2020]
