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| Titel |
Long-term changes in lower tropospheric baseline ozone concentrations at northern mid-latitudes |
| VerfasserIn |
D. D. Parrish, K. S. Law, J. Staehelin, R. Derwent, O. R. Cooper, H. Tanimoto, A. Volz-Thomas, S. Gilge, H.-E. Scheel, M. Steinbacher, E. Chan |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 12, no. 23 ; Nr. 12, no. 23 (2012-12-04), S.11485-11504 |
| Datensatznummer |
250011642
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| Publikation (Nr.) |
 copernicus.org/acp-12-11485-2012.pdf |
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| Zusammenfassung |
| 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 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. There is little if any evidence for
statistically significant differences in average rates of increase among the
sites, regardless of varying length of data records. At most sites (most
definitively at the European sites) the rate of increase has slowed over the
last decade (possibly longer), to the extent that at present O3 is
decreasing at some sites in some seasons, particularly in summer. The
average rate of increase before 2000 shows significant seasonal differences
(1.08 ± 0.09, 0.89 ± 0.10, 0.85 ± 0.11 and 1.21 ± 0.12% yr−1
in spring, summer, autumn and winter, respectively, over
North America and Europe). |
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