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| Titel |
Modelling the impact of megacities on local, regional and global tropospheric ozone and the deposition of nitrogen species |
| VerfasserIn |
Z. S. Stock, M. R. Russo, T. M. Butler, A. T. Archibald, M. G. Lawrence, P. J. Telford, N. L. Abraham, J. A. Pyle |
| 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 ; 13, no. 24 ; Nr. 13, no. 24 (2013-12-17), S.12215-12231 |
| Datensatznummer |
250085885
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| Publikation (Nr.) |
 copernicus.org/acp-13-12215-2013.pdf |
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| Zusammenfassung |
We examine the effects of ozone precursor emissions from megacities on
present-day air quality using the global chemistry–climate model UM-UKCA
(UK Met Office Unified Model coupled to the UK Chemistry and Aerosols model). The
sensitivity of megacity and regional ozone to local emissions, both from
within the megacity and from surrounding regions, is important for
determining air quality across many scales, which in turn is key for reducing
human exposure to high levels of pollutants. We use two methods, perturbation
and tagging, to quantify the impact of megacity emissions on global ozone. We
also completely redistribute the anthropogenic emissions from megacities, to
compare changes in local air quality going from centralised, densely
populated megacities to decentralised, lower density urban areas. Focus is
placed not only on how changes to megacity emissions affect regional and
global NOx and O3, but also on changes to NOy
deposition and to local chemical environments which are perturbed by the
emission changes.
The perturbation and tagging methods show broadly similar megacity impacts on
total ozone, with the perturbation method underestimating the contribution
partially because it perturbs the background chemical environment. The total
redistribution of megacity emissions locally shifts the chemical environment
towards more NOx-limited conditions in the megacities, which is more
conducive to ozone production, and monthly mean surface ozone is found to
increase up to 30% in megacities, depending on latitude and season. However,
the displacement of emissions has little effect on the global annual ozone
burden (0.12% change). Globally, megacity emissions are shown to contribute
~3% of total NOy deposition.
The changes in O3, NOx and NOy deposition described
here are useful for quantifying megacity impacts and for understanding the
sensitivity of megacity regions to local emissions. The small global effects
of the 100% redistribution carried out in this study suggest that the
distribution of emissions on the local scale is unlikely to have large
implications for chemistry–climate processes on the global scale. |
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