Abstract Cosmogenic radiosulfur ( 35 S) is produced in the atmosphere by high‐energy particle interactions and serves as a sensitive tracer of stratospheric intrusions. In May 2024, an extreme solar storm provided a rare opportunity to examine atmospheric 35 S responses to intense solar activity. We report daily 35 SO 4 2− measurements from surface air in subtropical China and identify two distinct enrichment events. Meteorological simulations and reanalysis data reveal that 35 S enrichments on May 16 resulted from a deep stratospheric intrusion that also drove a regional ozone pollution episode. In contrast, persistently elevated 35 S levels during May 9–15 occurred without stratospheric influence and coincided with strong solar energetic particle fluxes. These observations suggest that extreme solar storms may contribute to transient increases in atmospheric 35 S, highlighting the importance of high‐resolution cosmogenic radionuclide monitoring in modern days for interpreting past solar energetic events recorded by longer‐lived cosmogenic isotopes.
Zou et al. (Fri,) studied this question.