Comparative Study of Super Substorms during Geomagnetic Storm Time and Non-storm Time

As a fundamental coupling mode between the solar wind, magnetosphere, and ionosphere, substorms have profound impacts on the near-Earth space environment. Super substorms refer to those during which the maximum value of the AE or the SME index exceeds 2000 nT, featuring stronger energy injection processes and different response modes compared with normal substorms. In this study, based on an existing substorm list, we selected two cases of super substorms with similar solar wind conditions—one occurring during a geomagnetic storm and the other during a non-storm period. Using in-situ observation data from geosynchronous orbit satellites—the Los Alamos National Laboratory (LANL) and the Geostationary Operational Environmental Satellite (GOES), auroral electrojet and ring current parameters from OMNI and SuperMAG, as well as numerical simulation results from the Comprehensive Inner Magnetosphere-Ionosphere (CIMI) model, we conduct a comparative analysis of these two cases from the perspectives of particle injection, energy input, and ring current dynamics. The results show that: During geomagnetic storms, the propagation distance of super substorm signals may be shorter than that during non-storm periods, primarily due to differences in the background plasma environment; During non-storm periods, the SME index of super substorms exhibits a distinct bimodal structure as a function of local time; the occurrence of geomagnetic storms leads to enhanced oxygen ion flux, thereby intensifying the ring current during super substorms. By studying the similarities and differences between super substorms during and outside of geomagnetic storms, this research can better serve future studies on the physical processes and impact mechanisms of super substorms, as well as the relationship between super substorms and geomagnetic storms, further promoting the understanding of space weather and the Earth-space environment.