Measurements of CFC-11, CFC-12, and HCFC-22 total columns in the atmosphere at the St. Petersburg site in 2009–2019

Abstract. Monitoring atmospheric anthropogenic halocarbons plays an important role in tracking their concentrations accordance with international agreements on emissions of ozone-depleting substances and, thus, estimating the ozone layer recovery. Within Network for Detection Atmospheric Composition Change (NDACC), regular Fourier transform infrared (FTIR) measurements can provide information abundancies a global scale. We improved retrieval strategies deriving CFC-11 (CCl3F), CFC-12 (CCl2F2), and HCFC-22 (CHClF2) columns from IR solar radiation spectra measured by Bruker IFS125HR spectrometer at St. Petersburg site (Russia). used Tikhonov–Phillips regularization approach solving inverse problem optimized values parameters. tested developed comparison FTIR independent data. The analysis time series column-averaged dry air mole fractions (Xgas) 2009–2019 gives mean 225 pptv (parts per trillion volume; CFC-11), 493 (CFC-12), 238 (HCFC-22). Trend total −0.40 % yr−1 (CFC-11), −0.49 2.12 compared means, trends, seasonal variability XCFC-11, XCFC-12, XHCFC-22 to that (1) near-ground volume mixing ratios (VMRs), observational Mace Head, Ireland (GVMR), (2) 8–12 km VMRs, ACE-FTS averaged over 55–65∘ N latitudes (SVMR), (3) Xgas Whole Atmosphere Community Climate Model (WACCM) (WXgas). In general, data showed good agreement means within systematic errors considered. trends observed demonstrate smaller decrease rates XCFC-11 XCFC-12 than same increase rate XHCFC-22. As whole, Xgas, SVMR, WXgas qualitatively similar variations, while GVMR is significantly less, only WXHCFC-22 variations are essentially SVMRHCFC-22.