1Chalmers University of Technology, Göteborg, Sweden
2EMEP MSC-W, Norwegian Meteorological Institute, Oslo, Norway
3Institute of Astrophysics and Geophysics, University of Liège, Liège, Belgium
4Institute of Environmental Physics, University of Bremen, Bremen, Germany
5Karlsruhe Institute of Technology (KIT), Institute for Meteorology and Climate Research (IMK-ASF), Garmisch-Patenkirchen, Germany
6Karlsruhe Institute of Technology (KIT), Institute for Meteorology and Climate Research (IMK-ASF), Karlsruhe, Germany
*present address: Max-Planck-Institute for Meteorology, Hamburg, Germany
Abstract. Trends in the CO and C2H6 partial columns (~0–15 km) have been estimated from four European ground-based solar FTIR stations for the 1996–2006 time period. The CO trends from the four stations Jungfraujoch, Zugspitze, Harestua and Kiruna have been estimated to −0.45±0.16 % yr−1, −1.00±0.24 % yr−1, −0.62±0.19 % yr−1 and −0.61±0.16 % yr−1, respectively. The corresponding trends for C2H6 are −1.51±0.23 % yr−1, −2.11±0.30 % yr−1, −1.09±0.25 % yr−1 and −1.14±0.18 % yr−1. To find possible reasons for the CO trends, the global-scale EMEP MSC-W chemical transport model has been used in a series of sensitivity scenarios. It is shown that the trends are consistent with the combination of a 20 % decrease in the anthropogenic CO emissions seen in Europe and North America during the 1996-2006 period and a 20 % increase in the anthropogenic CO emissions in East Asia, during the same time period. The possible impacts of CH4 and biogenic volatile organic compounds (BVOCs) are also considered. The European and global-scale EMEP model have been evaluated against the measured CO and C2H6 partial columns from Jungfraujoch, Zugspitze, Bremen, Harestua, Kiruna and Ny-Ålesund. The European model reproduces, on average the measurements at the different sites fairly well and within 10–22 % deviation for CO and 14–31 % deviation for C2H6. Their seasonal amplitude is captured within 6–35 % and 9–124 % for CO and C2H6, respectively. However, 61–98 % of the CO and C26 partial columns in the European model are shown to arise from the boundary conditions, making the global-scale model a more suitable alternative when modeling theses two species. In the evaluation of the global model the average partial columns for year 2006 have shown to be within 1–9 % and 37–50 % for CO and C26, respectively. The global model sensitivity for assumptions done in this paper is also analyzed.