Understanding the distribution of atmospheric water vapor (H₂O) is crucial for global warming studies and climate change mitigation. In this study, we retrieved the ground layer, tropospheric and total columns of H₂O using ground-based high-resolution Fourier transform infrared spectrometry (FTIR). The H₂O total columns are obtained from near-infrared (NIR) and mid-infrared (MIR) spectra, and the ground layer and tropospheric H₂O columns are retrieved from the MIR spectrum. The total columns of H₂O retrieved from NIR and MIR have a good consistency (R = 0.989). Additionally, the ground layer H₂O columns have a similar seasonal variation to total columns and tropospheric columns but have a higher seasonal amplitude. The ground layer H₂O columns are close to the total columns and tropospheric columns in winter; however, in summer, the average difference between the ground layer and total columns and the value between the ground layer and tropospheric columns are large. This is mostly due to temperature variation. The temperature has a linear response to H₂O, and the relationship between surface temperature and ln(XH₂O) values in the ground layer, the entire atmosphere and the troposphere show a significantly positive correlation, and the correlation coefficient R is 0.893, 0.882 and 0.683, respectively. Furthermore, we selected the HYSPLIT model to simulate the back trajectories of air parcels in the four seasons in Hefei and find that the air mass transport has a significant impact on the local H₂O change. These results demonstrate that ground-based high-resolution FTIR technology has high accuracy and precision in observing the vertical distribution and seasonal changes of H₂O in different atmospheres.

Under the control of the Montreal Protocol and its amendments, hydrofluorocarbons (HCFCs) are used as temporary substitutes for ozone-depleting substances, such as chlorofluorocarbons, and are regulated for consumption and production. China plans to phase out HCFCs by 2030, and HCFC-22 (CHClF₂) is currently the most abundant HCFC in the atmosphere. This study measures the vertical profiles and total columns of atmospheric HCFC-22 from January 2017 to December 2022, based on the mid-infrared solar spectra recorded by the ground-based high-resolution Fourier transform infrared (FTIR) spectrometer at the Hefei remote sensing station. The HCFC-22 total columns over Hefei increased from 2017–2018 and gradually decreased in 2018–2022, with an annual variation rate of 5.98% and −1.02% ± 0.02%, respectively. Compared with the ACE-FTS satellite independent dataset, the FTIR data indicate good consistency with the ACE-FTS data at a 5–25 km altitude, with an average relative difference of −4.38 ± 0.83% between the vertical profiles. HCFC-22 emissions in the Yangtze River Delta from 2017 to 2022 are estimated, derived from measured total columns combined with the Lagrangian transport model and the Bayesian inversion technique. In the Yangtze River Delta, HCFC-22 emissions were high in 2017, with a value of 33.3 ± 16.8 kt, and decreased from 2018 to 2022, with a minimum of 27.3 ± 13.6 kt in 2022 during the 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.

Atmospheric dichlorodifluoromethane (CCl2F2, CFC-12), as a synthetic chemical agent, is a main stratospheric ozone-depleting substance in atmosphere. Studies of the detection techniques and the temporal and spatial distribution of CFC-12 have great significance in understanding the variation trend of regional CFCs and their influence on stratospheric ozone. In this study, the method of retrieving the vertical profile and total column for CFC-12 is studied based on ground-based high-resolution Fourier transform infrared spectroscopy (FTIR). The spectral window for CFC-12 retrieval is selected as 922.5–923.6 cm–1, where the interfering gases are H2O, O3, and CO2. The result of error analysis shows that the average total error is 1.27%, including the systematic error 0.76% and random error 1.02%. The vertical profiles and total columns of atmospheric CFC-12 in Hefei during the period from 2017 to 2020 were retrieved based on the optimal estimation algorithm. The vertical profiles of CFC-12 show that the concentration of atmospheric CFC-12 is high in the troposphere and low stratosphere at the altitude of 0–20 km, and then decreases, very low at height above 40 km. The total column average kernel of retrieved CFC-12 profiles is higher at 15–20 km, and the typical signal degree of freedom of CFC-12 is 1.217. Moreover, the long-term total columns of atmosphere CFC-12 observed show obvious seasonal variation in Hefei. Total columns of atmosphere CFC-12 are higher in summer and lower in winter and early spring. The maximum monthly concentration of CFC-12 is about 1.13 × 1016 mol·cm–2 in July, and the minimum monthly concentration is 1.00 × 1016 mol·cm–2 in March. Also, the annual average total columns of atmospheric CFC-12 decreased slightly from 2017 to 2020, with an increasing rate of –0.68%. This reflects the effect of China's implementation of CFCs control ban policy. Furthermore, in order to verify the accuracy of ground-based FTIR observation, we compare our ground-based observation data with ACE-FTS/ SCISAT satellite version 4.1 level 2 data. There are 16 pairs of matching points between satellite observation and ground observation data, and the correlation coefficient is 0.73 for two CFC-12 partial columns at the height of 16–28 km, showing good agreement between ground-based FTIR data and satellite data. The long-term observations demonstrate the accuracy and reliability of ground-based high-resolution FTIR technology for detecting the vertical distribution and seasonal variation of atmosphere CFC-12.