Solar Activity Impacts on Ionospheric Scintillation and Precise Point Positioning Based on Multi‐Year GNSS and Scintillation Observations

Solar activity induces ionospheric irregularities that degrade Global Navigation Satellite System (GNSS) performance through amplitude and phase scintillation. Although numerous studies have investigated event‐driven or regional responses, the nonlinear coupling between solar radiation, ionospheric scintillation, and precise point positioning (PPP) degradation remains insufficiently quantified. This study presents a multi‐year observational analysis integrating GNSS measurements, ionospheric scintillation monitoring data, and solar activity indices from 2017 to 2024, covering high‐, mid‐, and low‐latitude regions. By jointly examining extreme ultraviolet (EUV) radiation, coronal mass ejection activity, scintillation indices (S4 and ), cycle‐slip occurrences, and PPP errors, a distinct nonlinear response of ionospheric scintillation to solar radiation is identified. Results reveal an approximately “inverted V‐shaped” dependence of scintillation intensity on EUV flux, with a critical threshold near 0.35 W/m 2 . In addition, enhanced solar radiation can suppress ionospheric scintillation, leading to transient improvements in positioning accuracy. On the day of peak solar flare activity, GNSS positioning accuracy exhibits a slight improvement as a result of reduced scintillation effects. Both scintillation occurrences and cycle slips aligned more closely with variations in EUV radiation flux. Results also indicate that low‐latitude regions exhibited a higher frequency of amplitude scintillation events (S4 > 0.2) than high‐latitude areas. The results refine the understanding of sun–ionosphere–positioning coupling and offer potential insights for assessing GNSS reliability and anti‐interference strategies during periods of elevated solar activity.