On the Geoelectric Field Response to the SSC of the May 2024 Super Storm Over Europe

Solar variability can lead to significant disturbances, such as coronal mass ejections (CMEs). A CME impacting the Earth's magnetosphere often causes geomagnetic storms that affect not only the magnetosphere but also the ionosphere, the upper atmosphere, and even the ground. During extreme events, rapidly changing geomagnetic fields can create strong geomagnetically induced currents (GICs) at ground. These GICs can severely impact human technology, causing damage to high-voltage power transformers and leading to power outages, as well as corrosion in oil and gas pipelines. On 10 May 2024, the most intense geomagnetic storm since the Halloween 2003 storm impacted Earth's environment, causing auroras to appear at much lower latitudes than usual in both the northern and southern hemispheres. This study investigates the effects of geomagnetically induced electric fields (GIEs), and hence GICs, during the sudden storm commencement (SSC) of the geomagnetic storm on 10 May 2024, over Europe, using the European quasi-Meridional Magnetometer Array ground magnetometers. Despite the magnetometer array being placed in the late afternoon (18:00 LT), the combined influence of a strong solar wind dynamic pressure amplitude and a significant, long-lasting southward interplanetary magnetic field (IMF) ( nT) resulted in strong SSC amplitudes ( nT) at mid-low latitudes ( N). Results suggest that the CME-driven shock inclination in the meridional plane leads to high GIE driven only at high latitudes. In addition, the decomposition of the SSC disturbance field at ground into ionospheric (DP field) and magnetospheric (DL field) origin contribution should commend input to GIEs (and hence to GICs) from both DL and DP fields, rather than ionospheric current alone.