Unraveling Super Equatorial Plasma Bubbles (EPBs) Evolution During the 23 April 2023 Storm: Multi‐Instrument Observations and GITM‐SAMI3 Simulation

Abstract Storm‐time equatorial plasma bubble (EPB) dynamics play a critical role in space weather impacts on communication and navigation systems, yet the mechanisms governing their formation and evolution under storm conditions remain poorly understood. Here, we report two episodes of super EPBs observed during the April 23–24, 2023 interplanetary coronal mass ejection (ICME)‐driven storm, utilizing comprehensive observations together with coupled simulations of the Global Ionosphere Thermosphere Model and Sami3 is A Model of the Ionosphere (GITM‐SAMI3). Multi‐instrument data reveal that the first EPB episode emerged in the Africa‐Atlantic sector during the ICME sheath, while the second occurred over the America‐east Pacific region during magnetic cloud. Both EPBs evolved into super bubbles, ascending to magnetic latitudes beyond 35°, and were embedded within widened equatorial ionization anomalies and storm‐enhanced density. The coupled GITM–SAMI3 model, driven by high‐latitude conditions from the Space Weather Modeling Framework, successfully reproduced both observed EPB episodes. Quantitative analysis of the generalized linear Rayleigh–Taylor instability growth rates revealed that the E × B drift term dominated over thermospheric wind term in both magnitude and variability. Detailed investigation of EPB growth and suppression during the sheath and magnetic cloud periods highlights the controlling influence of external drivers. Notably, we identify an externally triggered EPB seeding mechanism linked to enhanced vertical velocity shear at the convergence of zonal eastward and westward prompt penetration electric fields in a longitudinally confined region. These results provide key new insights into storm‐time EPB evolution and pave the way for improved EPB forecast capability.