This study investigated the occurrence frequency, perturbation intensity, and spatial morphology of equatorial plasma bubbles (EPBs) in Taiwan from 2023 to 2024, during which solar activity increased significantly. Through the unified Rate of Total Electron Content Index (ROTI) threshold value (>0.9 TECU/min), this study found a significant increase in EPB events, from 74 in 2023 to 128 in 2024, which is closely related to the increase in solar flux and the increase in sunspot count. The intensity of flickering is measured by the VS4 index and peaks during the spring and autumn equinoxes, but significant activity is also observed during the summer solstices such as May and August, indicating that EPB formation can be extended to atypical seasons during the solar maximum. Latitude analysis shows that higher VS4 values correspond to a larger EPB extension range, up to about 28 degrees of latitude. The auxiliary data provided by the VIPIR ionospheric detector further validated the changes in the underlying ionosphere during the EPB event, with significant increases in h'F2 and foF2 values, consistent with the VS4 high-value event. The findings highlight the impact of solar driving forces on EPB behavior and highlight the importance of integrated diagnostic techniques in low-latitude GNSS vulnerability assessment.

This study explores the occurrence, intensity, and spatial morphology of Equatorial Plasma Bubbles (EPBs) over Taiwan during 2023–2024, a period marked by elevated solar activity. Using a consistent ROTI threshold (>0.9 TECU/min), EPB detection revealed a substantial increase in events—from 74 in 2023 to 128 in 2024—closely tied to rising solar flux and sunspot numbers.
Scintillation intensity, measured via the VS4 index, peaked during equinoctial months, but solstitial periods like May and August also showed notable activity, indicating solar maxima broaden EPB development beyond typical seasonal norms. Latitudinal analysis showed stronger VS4 values corresponded to greater EPB spread, up to ~28°.
Supporting data from VIPIR ionosonde observations confirmed bottom-side ionospheric responses, with elevated h’F2 and foF2 values matching intense EPB episodes. These findings highlight the influence of solar forcing on EPB behavior and underscore the importance of integrated diagnostics for GNSS vulnerability assessment in equatorial regions.

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