Extreme Geoeffectiveness by the Turbulent Sheath of the ICME of the 2024 October Space Weather Event

Abstract The impact of severe space weather events driven by interplanetary coronal mass ejections (ICMEs) on the space environment of planets remains an active area of research. The intense space weather event of 2024 October 10–11 was driven by an isolated ICME characterized by well-defined sheath and magnetic cloud structures, which offered a unique opportunity to investigate their sequential impacts on the terrestrial space environment. In situ plasma and magnetic field measurements from NASA’s ACE, Wind, and ISRO’s Aditya-L1 spacecraft are utilized to identify the structure of this ICME. Concurrently, data from GOES-16 and -18, along with observations from the Magnetospheric Multiscale mission, are employed to analyze the magnetosphere’s distinct response to the various components of the ICME. Intense magnetic field compression, driven by enhanced solar wind pressure in the ICME sheath, exposed geostationary satellites positioned in the morning and noon local time sectors to interplanetary space as the magnetopause boundary moved Earthward, reaching below 5 R E . Most of the intensification of the ring current took place within the transit of the ICME sheath, indicative of the superior role of the sheath plasma. During the passage of the turbulent ICME-sheath, a severe intensification of field-aligned currents (FACs), equatorward expansion, and multiple bands of FACs were noted within the Earth’s magnetosphere–ionosphere system, unlike in the magnetic cloud phase. These observations underscore the critical role of the ICME sheath in driving extreme space weather effects at Earth. Further, we contrast this storm’s drivers and its geoeffectiveness with those of the 2024 May 10 superstorm—the most extreme geomagnetic event at Earth in two decades.