Change characteristics of the Induced Geoelectric Field Observed by China Geoelectric Network During the Extreme Magnetic Storm of May 11, 2024

In this paper, we analyze the characteristics of the induced geoelectric field in mainland China during the extreme magnetic storm from May 10–12 2024, based on the data from China Geoelectric Network. Our analysis focuses on the magnitude of the induced geoelectric field changes, the ratio between isotropic short and long dipoles, and the variation in polarization direction across different regions during the sudden onset of the magnetic storm. Our study reveals that horizontal changes in the induced geoelectric field intensity are not confined to specific regions during the sudden onset magnetic storms. When analyzing the same-direction ratio, at most stations it showed a consistent ratio between short and long dipoles. The polarization orientation derived from long-dipole ratios suggests that there is no consistent alignment of land and sea directions on the ground surface. These results indicate that the variations in geoelectric field measurements are influenced by the underlying electrical structure at each station. These findings are further interpreted by using high-density electric exploration data. This paper provides a quantitative characterization of changes in the induced geoelectric field intensity across mainland China during the geomagnetic storms, offering a foundation for further analysis of regional geoelectric field electromagnetic phenomena.