Atmos. Chem. Phys. Discuss., 12, 13881-13931, 2012
© Author(s) 2012. This work is distributed
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This discussion paper has been under review for the journal Atmospheric Chemistry and Physics (ACP). Please refer to the corresponding final paper in ACP.
Long-term changes in lower tropospheric baseline ozone concentrations at northern mid-latitudes
D. D. Parrish1, K. S. Law2, J. Staehelin3, R. Derwent4, O. R. Cooper1,5, H. Tanimoto6, A. Volz-Thomas7, S. Gilge8, H.-E. Scheel9, M. Steinbacher10, and E. Chan11
1NOAA ESRL Chemical Sciences Division, 325 Broadway, Boulder, CO, USA
2UPMC Univ. Paris 06; Univ. Versailles Saint-Quentin; CNRS/INSU; UMR 8190, LATMOS/IPSL, Paris, France
3Institute for Atmospheric and Climate Science, ETHZ, Universitätstrasse 16, 8092 Zürich, Switzerland
4rdscientific, Newbury, Berkshire RG14 6LH, UK
5CIRES, University of Colorado, Boulder, CO, USA
6National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, Ibaraki 305-8506, Japan
7IEK-8, Forschungszentrum Juelich, 52425 Juelich, Germany
8Hohenpeissenberg Meteorological Observatory, German Meteorological Service (DWD), Hohenpeissenberg, Germany
9Karlsruhe Institute of Technology, IMK-IFU, 82467 Garmisch-Partenkirchen, Germany
10Swiss Federal Laboratories for Materials Science and Technology (EMPA), Duebendorf, Switzerland
11Science and Technology Branch, Environment Canada, 4905 Dufferin Street, Toronto, Ontario, Canada

Abstract. Changes in baseline (here understood as representative of continental to hemispheric scales) tropospheric O3 concentrations that have occurred at northern mid-latitudes over the past six decades are quantified from available measurement records with the goal of providing benchmarks to which retrospective model calculations of the global O3 distribution can be compared. Eleven data sets (ten ground-based and one airborne) including six European, (beginning in the 1950's and before) three North American (beginning in 1984) and two Asian (beginning in 1991) are analyzed. When the full time periods of the data records are considered a consistent picture emerges; O3 has increased at all sites in all seasons. At European and North American sites the average linear increase of O3 before 2000 was approximately 1% yr−1 relative to the site's 2000 yr mixing ratio in each season. For perspective, this rate of increase sustained from 1950 to 2000 corresponds to an approximate doubling. At most European sites and some North American sites the rate of increase has slowed over the last decade (possibly longer) of the records. The average linear rate of increase before 2000 shows significant seasonal differences (1.08 ± 0.09, 0.89 ± 0.08, 0.79 ± 0.12 and 1.22 ± 0.12% yr−1 in spring, summer, autumn and winter, respectively, over North America and Europe).

Citation: Parrish, D. D., Law, K. S., Staehelin, J., Derwent, R., Cooper, O. R., Tanimoto, H., Volz-Thomas, A., Gilge, S., Scheel, H.-E., Steinbacher, M., and Chan, E.: Long-term changes in lower tropospheric baseline ozone concentrations at northern mid-latitudes, Atmos. Chem. Phys. Discuss., 12, 13881-13931, doi:10.5194/acpd-12-13881-2012, 2012.
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