Spectrometric monitoring of atmospheric carbon tetrafluoride (CF4) above the Jungfraujoch station since 1989: evidence of continued increase but at a slowing rate
E. Mahieu1,R. Zander1,G. C. Toon2,M. K. Vollmer3,S. Reimann3,J. Mühle4,W. Bader1,B. Bovy1,B. Lejeune1,C. Servais1,P. Demoulin1,G. Roland1,P. F. Bernath5,6,C. D. Boone7,K. A. Walker7,8,and P. Duchatelet1,*E. Mahieu et al.E. Mahieu1,R. Zander1,G. C. Toon2,M. K. Vollmer3,S. Reimann3,J. Mühle4,W. Bader1,B. Bovy1,B. Lejeune1,C. Servais1,P. Demoulin1,G. Roland1,P. F. Bernath5,6,C. D. Boone7,K. A. Walker7,8,and P. Duchatelet1,*
Received: 14 Aug 2013 – Discussion started: 21 Aug 2013 – Revised: 22 Nov 2013 – Accepted: 17 Dec 2013 – Published: 31 Jan 2014
Abstract. The long-term evolution of the vertical column abundance of carbon tetrafluoride (CF4) above the high-altitude 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 ν3 band of CF4 centered at 1283 cm−1, and two additional ones to optimally account for weak but overlapping HNO3 interferences. The analysis reveals a steady accumulation of the very long-lived CF4 above the Jungfraujoch at mean rates of (1.38 ± 0.11) × 1013 molec cm−2 yr−1 from 1989 to 1997, and (0.98 ± 0.02) × 1013 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 CF4 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.