Occurrence of periodic plasmapause oscillations in response to a record-breaking superstorm

The plasmapause boundary can efficiently modulate magnetosphere-ionosphere coupling. During typical geomagnetic storms, the eroded plasmapause displays periodic oscillations that manifest as giant undulations of the aurora in the ionosphere. However, it remains unresolved whether such plasmapause oscillations occur during extreme storms. Here, we confirmed the occurrence of periodic plasmapause oscillations during the most intense superstorm over the past 20 years. Based on the auroral giant undulations, the extremely eroded plasmapause, down to 2 Earth radii (R E ), oscillated periodically at a scale of 1 R E in response to the May 2024 superstorm. Furthermore, we analyzed different and similar signatures of plasmapause oscillations during this superstorm and compared them with the signatures during typical storms. Our results suggest that plasmapause oscillations are an intrinsic and systematic pattern of external explosive energy input into the inner magnetosphere, thus providing physical constraints for global coupling models when addressing the extreme space weather conditions.