Unprecedented Multipoint Observation of Spatially Varying ICME Turbulence of Different Ages during October 2024 Extreme Solar Storm at 1 AU
Understanding turbulence in interplanetary coronal mass ejections (ICMEs) is fundamental to space plasma research and critical for assessing the impact of space weather on geospace. Turbulence governs energy cascade, plasma heating, magnetic reconnection, and solar wind magnetosphere coupling, thereby influencing both ICME evolution and geoeffectiveness. While previous event based and statistical studies have examined ICME turbulence and its radial evolution in great detail, no significant measurements of ICME magnetic turbulence at a single vantage point have been obtained from multiple observatories separated azimuthally. Here, we present the first multipoint analysis of magnetohydrodynamic (MHD) turbulence across ICME plasma regions, using four spacecraft at the Sun-Earth L1 point, separated by 80 RE (mesoscale) along the dawn-dusk direction. Using high-resolution magnetic field observations from ISRO's Aditya L1, NASA's Wind and ACE, and NOAA's DSCOVR, we analyze turbulence associated with the October 10, 2024, solar storm, which triggered the second strongest geomagnetic storm of solar cycle 25. Our results reveal significant variability and differing turbulence maturity across small separations, supported by analysis of field-aligned and perpendicular magnetic-field cascades, indicating strong anisotropies. Sheath turbulence is substantially modified by shock induced energy injection. Evidence of compressible turbulence and plasma energization at the flux rope interaction region indicates that internal processes, such as magnetic reconnection, strongly influence ICME plasma evolution, highlighting pronounced spatial variability in turbulence and plasma states observed by multiple L1 monitors near Earth and underscoring their potential role in space weather impacts.