Satellite and ground-based observations of Pc1 pulsations during a magnetic storm in March 2023

Abstract

We have analyzed electromagnetic ion-cyclotron oscillations of the Pc1 range (~1 Hz) recorded during the recovery phase of the March 25, 2023 magnetic storm at the network of ground stations in the Far East and at low-orbit SWARM satellites passing over the stations. The collected data made it possible to trace propagation of Pc1 waves through the ionosphere to Earth’s surface and along the ionosphere. While long-term (~1 hour) narrowband pulsations were observed at ground stations, satellites recorded only a short (~40 s) burst of transverse oscillations. Estimated coherence of signals between close SWARM-A and -C satellites, separated by ~1° longitude, gives a transverse scale of the wave packet in the ionosphere equal to ~90 km. The long duration of pulsations at ground stations is caused by waveguide propagation of signals along the ionosphere due to which the station “collects” signals from a large magnetospheric region. The presence of waveguide propagation is confirmed by the orientation of the polarization ellipse of ground-based Pc1 pulsations relative to the site of injection of waves into the ionosphere. It is hypothesized that ion-cyclotron instability develops in the form of localized and short-lived bursts, but the mechanism of such a regime remains unclear.

Keywords

• Pc1 pulsations
• electromagnetic ion-cyclotron waves
• SWARM satellites