RadCube MAGIC observations of complex field aligned currents associated with a supersubstorm during the May 2024 geomagnetic storm

Abstract Geomagnetic storms are a key driver of space weather impacts. The enhancement of ionospheric currents during these events can produce geomagnetically induced currents (GICs) that may interfere with the operation of ground infrastructure such as power grids, pipelines, and railway networks. It is therefore critical to understand how, why, and when very intense GICs may occur during an extended geomagnetic storm interval. Supersubstorms are extremely intense substorms which may occur during the main or recovery phases of geomagnetic storms. These rare events bear special investigation because they may have a significant impact on GIC formation during extreme geomagnetic storms. Multiple supersubstorms were observed during the May 2024 geomagnetic storm, and here we report new observations of supersubstorm field aligned currents (FACs), observed in situ by the MAGnetometer from Imperial College (MAGIC) instrument on the RadCube technology demonstration CubeSat. These measurements provide new insight into the detailed structure of supersubstorm FACs, complementing global FAC maps, and reveal an extended spatial region containing magnetic fluctuations across a broad range of spatial/temporal scales, including intense localised current spikes. As well as revealing new details about supersubstorm-related FACs, these observations illustrate the need for dense constellations of low-Earth-orbit satellite-based magnetometers for space weather monitoring.