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| Titel |
Primary versus secondary contributions to particle number concentrations in the European boundary layer |
| VerfasserIn |
C. L. Reddington, K. S. Carslaw, D. V. Spracklen, M. G. Frontoso, L. Collins, J. Merikanto, A. Minikin, T. Hamburger, H. Coe, M. Kulmala  , P. Aalto, H. Flentje, C. Plass-Dülmer, W. Birmili, A. Wiedensohler, B. Wehner, T. Tuch, A. Sonntag, C. D. O'Dowd, S. G. Jennings, R. Dupuy, U. Baltensperger, E. Weingärtner, H.-C. Hansson, P. Tunved, P. Laj, K. Sellegri, J. Boulon, J.-P. Putaud, C. Gruening, E. Swietlicki, P. Roldin, J. S. Henzing, M. Moerman, N. Mihalopoulos, G. Kouvarakis, V. Ždímal, N. Zikova, A. Marinoni, P. Bonasoni, R. Duchi |
| 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. 23 ; Nr. 11, no. 23 (2011-12-05), S.12007-12036 |
| Datensatznummer |
250010234
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| Publikation (Nr.) |
 copernicus.org/acp-11-12007-2011.pdf |
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| Zusammenfassung |
| It is important to understand the relative contribution of primary and
secondary particles to regional and global aerosol so that models can
attribute aerosol radiative forcing to different sources. In
large-scale models, there is considerable uncertainty associated with
treatments of particle formation (nucleation) in the boundary layer
(BL) and in the size distribution of emitted primary particles, leading
to uncertainties in predicted cloud condensation nuclei (CCN)
concentrations. Here we quantify how primary particle emissions and
secondary particle formation influence size-resolved particle number
concentrations in the BL using a global aerosol microphysics model and
aircraft and ground site observations made during the May 2008 campaign
of the European Integrated Project on Aerosol Cloud Climate Air Quality
Interactions (EUCAARI). We tested four different parameterisations for BL
nucleation and two assumptions for the emission size distribution of
anthropogenic and wildfire carbonaceous particles. When we emit
carbonaceous particles at small sizes (as recommended by the Aerosol
Intercomparison project, AEROCOM), the spatial distributions of
campaign-mean number concentrations of particles with diameter >50 nm
(N50) and >100 nm (N100) were well captured
by the model (R2≥0.8) and the normalised mean bias (NMB) was
also small (−18% for N50 and −1% for N100).
Emission of carbonaceous particles at larger sizes, which we consider to be
more realistic for low spatial resolution global models, results in equally
good correlation but larger bias (R2≥0.8, NMB = −52%
and −29%), which could be partly but not entirely compensated by
BL nucleation. Within the uncertainty of the observations and accounting for
the uncertainty in the size of emitted primary particles, BL nucleation makes
a statistically significant contribution to CCN-sized particles at less than a
quarter of the ground sites. Our results show that a major source of
uncertainty in CCN-sized particles in polluted European air is the emitted
size of primary carbonaceous particles. New information is required not just
from direct observations, but also to determine the "effective emission
size" and composition of primary particles appropriate for different resolution
models. |
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