Ring current wedge in nightside during substorms

Large-scale current systems are often disturbed during geomagnetically active time. Based on previous simulations, our work proposes that except for the substorm current wedge (SCW) that connects tail current to ionosphere via a pair of Region-1 sense field-aligned currents (FACs), there exists another wedge-shaped current structure in the nightside current system during substorms, connecting the ring current to the ionosphere. We refer to this structure as the ring current wedge (RCW). The RCW is difficult to be distinguished from the SCW using observations from ground-based magnetometer stations because of their similarity and close distribution in latitude. Furthermore, due to its shorter duration compared to SCW, RCW is often overlooked in previous studies. In this paper, we use global MHD simulations to investigate the storm event on December 1, 2023, in which the IMF Bz reversal from ~+5 nT to ~-25 nT, providing favorable conditions for magnetotail reconnection. During a strong substorm injection, both tail current and ring current were interrupted in midnight sector, forming distinct SCW and RCW structures that lasted for ~30 minutes. Additionally, by superposing SuperDARN global convection images with AMPERE-derived FACs, a reversed, counter-clockwise convection cell was observed at mid-latitudes in the duskside ionosphere, as expected to be formed between SCW and RCW. The reverse convection confirmed that SCW and RCW are different current structures.