Equatorial Electrojet (EEJ) Index Variations During the 1 January 2025 Geomagnetic Storm

Equatorial Electrojet (EEJ) index data derived from magnetometer observations at two stations in South America: Huancayo (HUA; magnetic latitude 2.28°S) and Kourou (KOU; magnetic latitude 14.27°N). The dataset contains 1-minute EEJ variations during the 1 January 2025 geomagnetic storm. The EEJ index was calculated from the difference in the horizontal magnetic field component between the Huancayo and Kourou stations and was used as a proxy for storm-time equatorial electric field variability. These data were employed to investigate prompt penetration electric fields (PPEFs), F-layer uplift, and the formation and evolution of equatorial plasma bubbles (EPBs) over Southeast Asia during the storm. The dataset was used in the preparation of the scientific manuscript entitled "Storm-Time Penetration Electric Fields Driving Equatorial Plasma Bubble Formation Over Indonesia on 1 January 2025" by Suraina et al.