Sawtooth events are storm‑time surges of energetic particles with sharp rises and slow decays repeating every 2–4 h. From 2008–2016 they occur mostly in the solar cycle’s rising and declining phases and nearly always during geomagnetic storms. Geostationary data show near‑global, near‑simultaneous injections but strong magnetic changes only at midnight. This favors magnetotail reconnection and fast convection; sawteeth resemble a storm‑time substorm mode.

The goal of this study was to explore how a once-in-a-century storm could affect the Swedish power grid by combining past storm data with a simplified model of the power grid. We identified regions that may be at higher risk and estimated how many power lines could be exposed to large voltages. These insights reveal vulnerable areas and provide a foundation for strengthening preparedness against rare, high-impact events.

We analyzed the average magnetopause position influenced by solar winds and interplanetary magnetic field (IMF) using data from the Time History of Events and Macroscale Interactions during Substorms (THEMIS), Radiation Belt Storm Probes (RBSP), and Magnetospheric Multiscale (MMS) mission from 2016–2020. Minimal movement occurred during substorm phases. The magnetopause moved to its closest inward position during the growth phase and relaxed from peak to recovery as in Shue's model.

We have examined events during which the measured magnetic field on the ground changes very rapidly, causing a risk to technological conductor networks. According to our results, such events occur when strong electric currents in the ionosphere at 100 km altitude are abruptly modified by sudden compression or expansion of the magnetospheric magnetic field farther in space.