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| Titel |
Aerosol modelling in Europe with a focus on Switzerland during summer and winter episodes |
| VerfasserIn |
S. Aksoyoglu, J. Keller, I. Barmpadimos, D. Oderbolz, V. A. Lanz, A. S. H. Prévôt, U. Baltensperger |
| 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 ; 11, no. 14 ; Nr. 11, no. 14 (2011-07-26), S.7355-7373 |
| Datensatznummer |
250009951
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| Publikation (Nr.) |
 copernicus.org/acp-11-7355-2011.pdf |
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| Zusammenfassung |
| This paper describes aerosol modelling in Europe with a focus on Switzerland
during summer and winter periods. We modelled PM2.5 (particles smaller
than 2.5 μm in aerodynamic diameter) for one summer and two winter
periods in years 2006 and 2007 using the CAMx air quality model. The
meteorological fields were obtained from MM5 simulations. The modelled wind
speeds during some low-wind periods, however, had to be calibrated with
measurements to use realistic input for the air quality model. The detailed
AMS (aerosol mass spectrometer) measurements at specific locations were used
to evaluate the model results. In addition to the base case simulations, we
carried out sensitivity tests with modified aerosol precursor emissions, air
temperature and deposition. Aerosol concentrations in winter 2006 were twice
as high as those in winter 2007, however, the chemical compositions were
similar. CAMx could reproduce the relative composition of aerosols very well
both in the winter and summer periods. Absolute concentrations of aerosol
species were underestimated by about 20 %. Both measurements and model
results suggest that organic aerosol (30–38 %) and particulate nitrate
(30–36 %) are the main aerosol components in winter. In summer, organic
aerosol dominates the aerosol composition (55–57 %) and is mainly of
secondary origin. The contribution of biogenic volatile organic compound
(BVOC) emissions to the formation of secondary organic aerosol (SOA) was
predicted to be very large (>95 %) in Switzerland. The main
contributors to the modelled SOA concentrations were oxidation products of
monoterpenes and sesquiterpenes as well as oligomerization of oxidized
compounds. The fraction of primary organic aerosol (POA) derived from
measurements was lower than the model predictions indicating the importance
of volatility of POA, which has not yet been taken into account in CAMx.
Sensitivity tests with reduced NOx and NH3 emissions suggest that
aerosol formation is more sensitive to ammonia emissions in winter in a
large part of Europe. In Switzerland however, aerosol formation is predicted
to be NOx-sensitive. In summer, effects of NOx and NH3
emission reductions on aerosol concentrations are predicted to be lower
mostly due to lower ammonium nitrate concentrations. In general, the
sensitivity to NH3 emissions is weaker in summer due to higher NH3
emissions. |
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