Spectrometric monitoring of atmospheric carbon tetrafluoride (CF<sub>4</sub>) above the Jungfraujoch station since 1989: evidence of continued increase but at a slowing rate

Abstract

Abstract. The long-term evolution of the vertical column abundance of carbon tetrafluoride (CF 4 ) above the highaltitude Jungfraujoch station (Swiss Alps, 46.5 • N, 8.0 • E, 3580 m a.s.l.) has been derived from the spectrometric analysis of Fourier transform infrared solar spectra recorded at that site between 1989 and 2012. The investigation is based on a multi-microwindow approach, two encompassing pairs of absorption lines belonging to the R-branch of the strong ν 3 band of CF 4 centered at 1283 cm −1 , and two additional ones to optimally account for weak but overlapping HNO 3 interferences. The analysis reveals a steady accumulation of the very long-lived CF 4 above the Jungfraujoch at mean rates of (1.38 ± 0.11) × 10 13 molec cm −2 yr −1 from 1989 to 1997, and (0.98 ± 0.02) × 10 13 molec cm −2 yr −1 from 1998 to 2012, which correspond to linear growth rates of 1.71 ± 0.14 and 1.04 ± 0.02 % yr −1 respectively referenced to 1989 and 1998. Related global CF 4 anthropogenic emissions required to sustain these mean increases correspond to 15.8 ± 1.3 and 11.1 ± 0.2 Gg yr −1 over the above specified time intervals. Findings reported here are compared and discussed with respect to relevant northern mid-latitude results obtained remotely from space and balloons as well as in situ at the ground, including new gas chromatography mass spectrometry measurements performed at the Jungfraujoch since 2010.

High resolution FTIR and diode laser spectroscopy of trifluoromethylacetylene and tetrafluoromethane in a supersonic jet expansion

“…Carbontetrafluoride (R14, PCF-14, Halocarbon 14), CF 4 , is an important trace gas in the Earth's atmosphere both of natural and man-made origin and its spectroscopy has been extensively studied in this context (see [66-74, 80-88, 110, 111] and references therein). Spectroscopic monitoring of CF 4 has been continued on the Jungfraujoch station in the Swiss Alps for several decades [112]. CF 4 has an exceptionally long lifetime, estimated to be more than 50'000 years in the Earth's atmosphere [113,114].…”

Improved FTIR retrieval strategy for HCFC-22 (CHClF<sub>2</sub>), comparisons with in situ and satellite datasets with the support of models, and determination of its long-term trend above Jungfraujoch

“…We confirm the decreasing of HCFC-22 growth rate during the last decade as observed by recent in situ studies (Montzka et al, 2015;Simmonds et al, 2017) The fact that HCFC-22 emissions have been constant since 2007 and, therefore, that HCFC-22 growth rate has ceased to exhibit a continuous increase over the last decade, as highlighted in this paper and other works, seems to promise a fulfilment of the Montreal Protocol and its amendments in the years to come. Recent HCFC trends even suggest that the 2013 cap on global production (Montreal Protocol) has been respected well in advance (Montzka et al, 2015;Mahieu et al, 2017). Finally, this improvement in retrieval strategy, leading to the determination of partial columns, could be applied to other source gases essential for monitoring chlorine in the atmosphere (e.g.…”

Improved FTIR retrieval strategy for HCFC-22 (CHClF2), comparisons with in situ and satellite datasets with the support of models, and determination of its long-term trend above Jungfraujoch

“…Note that our retrieved mixing ratios correspond to moist air values while AGAGE measurements are reported as dry air mole fractions. The difference between the two should be here insignificantly small because of the very dry air conditions experienced at JFJ (Lejeune et al, 2017;Mahieu et al, 2014).…”