Abstract On 10 May 2024, an interplanetary coronal mass ejection‐driven shock impacted the dayside magnetopause, compressing it to ∼5 R E . A northward interplanetary magnetic field suppressed dayside reconnection and allowed a clear investigation of the magnetosphere response. We use coordinated GOES and THEMIS observations to examine the magnetopause motion and its boundary layer evolution. Our study provides, for the first time, ion energy flux spectra, pitch angle distributions, and ion moments derived from the GOES‐16 data. The energy flux spectrum from GOES‐16 reveals a geostationary magnetopause crossing 32 s prior to the magnetosheath magnetic field turning southward. The magnetopause was compressed at a speed of ∼300 km s −1 , with the depletion layer thickening by a factor of 3.8. We identify a localized compressed region that expands rapidly earthward. Within this region, a rare three‐energy‐level ion structure is observed, indicating the transport of ions from a plasmaspheric plume.
Li et al. (Fri,) studied this question.