Manifestations of Strong IMF-By on the Equatorial Ionospheric Electrodynamics During 10 May 2024 Geomagnetic Storm

Abstract

Understanding the effects of east-west component of interplanetary magnetic field (IMF-By) on the equatorial ionospheric electrodynamics is challenging due to the complex response caused by the simultaneous occurrence of multiple mechanisms during disturbed times. The extreme geomagnetic storm on 10 May 2024 caused by multiple-ICME interactions accompanied with unprecedented IMF-By magnitudes and its polarity, changed from west to east by 130 nT during northward IMF-Bz turning. The ground ionosonde observations of h’F from near-equatorial locations, along with the latitudinal profiles of plasma densities from Swarm satellites reveal the first observational evidence of the impact of strong IMF-By near the dusk-terminator (17–19.5 LT), causing strong dawn-to-dusk ionospheric electric fields during northward IMF-Bz. This electric field produces large uplift of the ionospheric plasma near equator and subsequent super-fountain effect near the dusk. The combined effect of increased IMF-By amplitudes and viscous terms might have resulted into the enhanced coupling of solar wind with the magnetosphere.