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| Titel |
A multi-model analysis of vertical ozone profiles |
| VerfasserIn |
J. E. Jonson, A. Stohl, A. M. Fiore, P. Hess, S. Szopa, O. Wild, G. Zeng, F. J. Dentener, A. Lupu, M. G. Schultz, B. N. Duncan, K. Sudo, P. Wind, M. Schulz, E. Marmer, C. Cuvelier, T. Keating, A. Zuber, A. Valdebenito, V. Dorokhov, H. Backer, J. Davies, G. H. Chen, B. Johnson, D. W. Tarasick, R. Stübi, M. J. Newchurch, P. Gathen, W. Steinbrecht, H. Claude |
| 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 ; 10, no. 12 ; Nr. 10, no. 12 (2010-06-30), S.5759-5783 |
| Datensatznummer |
250008582
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| Publikation (Nr.) |
 copernicus.org/acp-10-5759-2010.pdf |
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| Zusammenfassung |
A multi-model study of the long-range transport of ozone and its precursors
from major anthropogenic source regions was coordinated by the Task Force
on Hemispheric Transport of Air Pollution (TF HTAP) under the Convention
on Long-range Transboundary Air Pollution (LRTAP). Vertical profiles of
ozone at 12-h intervals from 2001 are available from twelve of the
models contributing to this study and are compared here with observed
profiles from ozonesondes. The contributions from each major source
region are analysed for selected sondes, and this analysis is supplemented
by retroplume calculations using the FLEXPART Lagrangian particle dispersion
model to provide insight into the origin of ozone transport events and
the cause of differences between the models and observations.
In the boundary layer ozone levels are in general strongly affected by
regional sources and sinks. With a considerably longer lifetime in the free
troposphere, ozone here is to a much larger extent affected by processes on a
larger scale such as intercontinental transport and exchange with the
stratosphere. Such individual events are difficult to trace over several days
or weeks of transport. This may explain why statistical
relationships between models
and ozonesonde measurements are far less satisfactory than shown in
previous studies for surface measurements at all seasons.
The lowest bias between model-calculated ozone profiles and the
ozonesonde measurements is seen in
the winter and autumn months. Following the increase in
photochemical activity in the spring and summer months, the spread in model
results increases, and the agreement between ozonesonde measurements and the
individual models deteriorates further.
At selected sites calculated contributions to ozone levels in the free
troposphere from intercontinental transport are shown. Intercontinental
transport is identified based on differences in model
calculations with unperturbed emissions and emissions
reduced by 20% by region. Intercontinental transport of ozone is finally
determined based on differences in model ensemble calculations. With
emissions perturbed by 20% per region,
calculated intercontinental contributions to ozone in the free troposphere
range from less than 1 ppb to 3 ppb, with small contributions in winter.
The results are corroborated by the retroplume
calculations. At several locations the seasonal contributions to ozone in the
free troposphere from intercontinental transport differ from what was
shown earlier at the surface using the same dataset. The large spread in
model results points to a need of further evaluation of the chemical
and physical processes in order to improve the credibility of global model
results. |
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