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Atmos. Chem. Phys. Discuss., 9, 2381-2415, 2009
www.atmos-chem-phys-discuss.net/9/2381/2009/ doi:10.5194/acpd-9-2381-2009 © Author(s) 2009. This work is distributed under the Creative Commons Attribution 3.0 License. |
Inter-comparison of four different carbon monoxide measurements techniques and evaluation of the long-term carbon monoxide time series of Jungfraujoch
Empa, Swiss Federal Laboratories for Materials Testing and Research, Laboratory for Air Pollution/Environmental Technology, 8600 Dübendorf, Switzerland
Abstract. The 12-year record (1996–2007) of continuous carbon monoxide (CO) measurements of the high-alpine site Jungfraujoch (JFJ), Switzerland, was investigated with a focus on trend analysis. To date this is one of the longest time series of continuous CO measurements in the free troposphere over Central Europe. A significant negative trend was observed at JFJ with a decrease of 21.4±0.3% in the investigated period, or an average annual decrease of 2.65±0.04 ppb/yr (1.78%/yr). These results were compared with emission inventory data reported to the Long-range Transboundary Air Pollution (LRTAP) Convention. It could be shown that long range transport significantly influences the CO levels observed at JFJ, with air masses of non-European origin contributing to at least a third to observed mixing ratios.
Such trend analysis and inter-comparison with emission inventories are only possible with data of known quality. To this end, the Non-dispersive Infrared Absorption (NDIR) technique used for CO measurements at JFJ was inter-compared over two months using three additional analytical techniques, namely Vacuum UV Resonance Fluorescence (VURF), gas chromatographic separation with a mercuric oxide reduction detector (GC/HgO), and gas chromatographic separation followed by reduction on a nickel catalyst and analysis by a flame ionization detector (GC/FID). The agreement among all techniques was better than 2% for one-hourly averages which confirmed the suitability of the NDIR method for CO measurements even at remote sites.
Citation: Zellweger, C., Hüglin, C., Klausen, J., Steinbacher, M., Vollmer, M. K., and Buchmann, B.: Inter-comparison of four different carbon monoxide measurements techniques and evaluation of the long-term carbon monoxide time series of Jungfraujoch, Atmos. Chem. Phys. Discuss., 9, 2381-2415, doi:10.5194/acpd-9-2381-2009, 2009.