Multi-Point Observations of Extremely Fast Magnetopause Compression During the May 2024 Superstorm

The magnetopause is usually in motion, but it remains unclear how fast its large-scale motion can be. In this study, we address this issue by using multiple spacecraft observations during the May 2024 superstorm, as there are five spacecraft located in the dayside magnetosphere, providing a unique opportunity to capture the magnetopause motion. Observations from three Time History of Events and Macroscale Interactions during Substorms (THEMIS) spacecraft indicate that the magnetopause compression speed, driven by solar wind dynamic pressure enhancement associated with the CME shock, exceeds 200 (Formula presented.), with a large initial acceleration of ∼30 (Formula presented.). Combined with observations from two Geostationary Operational Environmental Satellite (GOES) spacecraft, the complete magnetopause compression process is captured, suggesting the subsolar magnetopause is compressed by ∼2.8 Earth radii in about 97 s. The comparison with the much slower magnetopause erosion (<20 km s⁻¹) caused by the southward interplanetary magnetic field (IMF) highlights the critical role of dynamic pressure enhancement in driving the fast magnetopause compression. A statistical survey further indicates that similar sharp solar wind dynamic pressure enhancements occur at a rate of less than 1 time per year on average and are usually associated with coronal mass ejections (CMEs). This study deepens our understanding of solar wind–magnetosphere coupling under extreme solar wind conditions.