First ground-based Fourier transform infrared (FTIR) spectrometer observations of HFC-23 at Rikubetsu, Japan, and Syowa Station, Antarctica

Abstract. We have developed a procedure for retrieving atmospheric abundances of HFC-23 (CHF3) with ground-based Fourier transform infrared (FTIR) spectrometer and analyzed the spectra observed at Rikubetsu, Japan (43.5? N, 143.8? E), Syowa Station, Antarctica (69.0? S, 39.6? E). The FTIR retrievals were carried out SFIT4 retrieval program, two spectral windows 1138.5–1148.0 cm?1 1154.0–1160.0 in overlapping ?2 ?5 vibrational–rotational transition bands used to avoid strong H2O absorption features. considered O3, N2O, CH4, H2O, HDO, CFC-12 (CCl2F2), HCFC-22 (CHClF2), peroxyacetyl nitrate (PAN) (CH3C(O)OONO2), HCFC-141b (CH3CCl2F), HCFC-142b (CH3CClF2) be interfering species. Vertical profiles CH4 are preliminarily retrieved other independent because these may induce large uncertainties retrieval. Each has only one piece vertical information sensitivity troposphere lower stratosphere. Retrieval errors mainly arise from systematic spectroscopic parameters obtain HFC-23, abundances. For comparison between FTIR-retrieved total columns surface dry-air mole fractions provided by AGAGE (Advanced Global Atmospheric Gases Experiment), column-averaged (XHFC-23) calculated. XHFC-23 values Rikubetsu Station negative biases ?15 % ?20 ?25 compared datasets, respectively. These might come parameters. trend data was derived December February (DJF) observations, which represent background when an air mass reaching least influence transport emissions nearby countries. DJF over 1997–2009 period is 0.810 ± 0.093 ppt yr?1 (ppt: parts per trillion), good agreement annual global mean datasets 12-box model same (0.820 0.013 yr?1). 2008–2019 0.928 0.108 yr?1, consistent situ measurements Trinidad Head (41.1? 124.2? W) (0.994 0.001 2007–2016 0.819 0.071 that Cape Grim (40.7? 144.7? E) (0.874 0.002 Although there both sites, results indicate observations capability monitor long-term HFC-23. If this measurement technique extended Network Detection Composition Change (NDACC) sites around world, reported would complement filling spatial temporal gaps lead improved insights about changes regional its role warming.