Characterising the Global Magnetospheric Response to Major ICME Events

In May and October 2024 the aurora was observed at unusually low latitudes across Europe during intervals of significantly enhanced geomagnetic activity in response to the arrival of multiple Interplanetary Coronal Mass Ejections (ICMEs). These storms were two of the biggest storms in Solar Cycle 25 so far. We examine the global magnetospheric response during these intervals using in-situ solar wind and magnetospheric field-aligned current observations. Our analysis suggests that these geomagnetic storms were so large that the magnetospheric activity saturated and could not increase further. We extend our analysis to include large storms from solar cycles 23 – 25 to statistically compare the geomagnetic response to intense storms. We also contrast this against the geomagnetic response to weak and moderate storms.