Magnetosphere‐Ionosphere Current Systems During Sawtooth Oscillations of October 2024 Geomagnetic Storm

Abstract The magnetosphere can undergo periodic loading and unloading of magnetic energy, a mode of activity known as sawtooth oscillations. Whether individual oscillations represent intensified substorms or a distinct form of magnetospheric activity remains an open question. We investigate the magnetosphere–ionosphere (M–I) current systems during the sawtooth oscillations of the October 2024 geomagnetic storm to examine how the system reconfigures in space and time, using combined observations from SuperMAG ground magnetometers, AMPERE field‐aligned current maps, and GOES magnetic field measurements. Our results show that each oscillation is characterized by a sequential development of two distinct current wedges: a substorm current wedge (SCW) centered in the dusk‐to‐midnight sector, followed by a dawnward current wedge (DCW) centered at dawn. The SCW develops at the onset of each oscillation, spreads azimuthally, and extends ∼10 hr in MLT. The DCW forms during the decay of the SCW or after its disappearance, exhibits limited azimuthal motion, and maintains a relatively stationary morphology with a comparable MLT extent. While the SCW resembles typical substorms, albeit with larger MLT extents, the DCW is primarily observed for storm‐time substorms. Moreover, the DCW identified here differs from previously reported storm‐time DCW by exhibiting distinct onsets and nearly stationary MLT distributions without clear expansion from the midnight. These distinctions suggest that magnetotail configuration and dynamics during sawtooth oscillations differ systematically from those during non‐storm time substorms.