Variation and Transport Characteristics of Atmospheric SF6 Column Concentrations over Hefei Retrieved from Ground-Based Remote Sensing Observations

Sulfur hexafluoride (SF6) is a typical long-lived greenhouse gas that has attracted considerable attention due to its extremely long atmospheric lifetime and high global warming potential. In this study, atmospheric SF6 column concentrations from 2023 to 2025 were retrieved using ground-based high-resolution Fourier transform infrared (FTIR) remote sensing observations at the Hefei site, China. The seasonal variation and annual trends of SF6 were analyzed, and the potential influencing regions and transport characteristics of high-value events were investigated by combining wind direction statistics with backward trajectory clustering analysis. The results show that high SF6 column concentrations over Hefei mainly occurred in summer, while relatively low concentrations appeared in winter during the observation period from 2023 to 2025. The average total column concentration of SF6 is 2.80 × 1014 molec·cm−2, the average dry-air column-averaged mole fraction is 13.06 ppt, and the annual growth rate is 0.88 ppt yr−1. The high-value events of SF6 at the Hefei site are mainly concentrated in summer, and the wind direction mainly corresponds to the northeast and the southeast wind. The air masses with high concentrations of SF6 mainly originated from the transportation path in the nearby southern regions of the station. During summer, the season with relatively higher SF6 concentrations, the air masses were mainly southerly and easterly winds. The results of this study provide observational evidence and scientific support for understanding the characteristics of variation in atmospheric SF6 column concentrations over Hefei and the influence of regional transport on high SF6 values.