Pronounced Meso‐Scale Zonal Differences in Ionospheric TEC Under Diverse Geomagnetic Conditions Based on Beidou GEO Observations in May 2024

The spatial and temporal characteristics of meso‐scale zonal differences in ionospheric total electron content (TEC) and their relationship with geomagnetic conditions remain insufficiently understood. This study utilized one month of Beidou geostationary orbit (GEO) satellite observations of TEC in May 2024 to systematically investigate zonal TEC variations at mid/low latitudes in the Asian‐Australian sector. Pronounced zonal variations were observed in both hemispheres, with significant differences intermittently detected at receivers RTKV (31.0°N, 114.5°E), GDGZ (23.1°N, 113.3°E), and COCO (12.2°S, 96.8°E) during the month. These differences were strongly linked to the morphological evolution of the Equatorial Ionization Anomaly (EIA), particularly when its poleward edge approached the ionospheric pierce points. Moreover, a suppression of zonal differences was observed prior to the onset of the geomagnetic storm, which may be attributed to the diminished or obscured morphology of the EIA accompanied by the intensification of geomagnetic activity. Analysis of additional equinox storms in recent years indicated that the suppression process is not accidental. These findings highlighted the necessity of high‐resolution TEC observations for capturing meso‐scale zonal TEC differences, and further revealed that these zonal differences were driven by EIA dynamics and geomagnetic activity effects.