Comparative Dynamics of Substorms and Sawtooth Events

We present a comprehensive comparative analysis of magnetospheric substorms and sawtooth events using multi‐point observations from ground‐based magnetometers, geostationary satellites, and the Time History of Events and Macroscale Interactions during Substorms mission. Our analysis reveals that despite distinct solar wind driving conditions, with sawtooth events occurring during sustained southward interplanetary magnetic field and elevated proton densities versus more variable conditions for isolated substorms, both phenomena exhibit similar magnetic field dipolarization signatures at 8–10 in the magnetotail. This similarity is consistent with a shared near‐tail reconfiguration process, though it does not uniquely constrain the global onset mechanism or demonstrate that the entire energy release chain is identical across event types. Key differences emerge in the magnetospheric configuration: Sawtooth events maintain persistently stretched field lines at geosynchronous orbit while producing globally distributed and sustained auroral electrojet activity, compared to more dipolar geostationary configurations and clear substorm electrojet phases during isolated substorms. The locally confined midnight‐sector dipolarizations at GEO, concurrent with global particle injections, indicate that drift physics in the stretched field configuration plays a crucial role in azimuthal particle redistribution. We find evidence of a characteristic ∼3‐hr periodicity in both phenomena, whose origin may involve intrinsic magnetotail loading‐unloading timescales, solar wind persistence on comparable scales, or both. Our results imply that sawtooth events represent a storm‐time mode of repetitive substorm activity under continuously driven conditions rather than a fundamentally distinct magnetospheric process.