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| Titel |
The contribution of boundary layer nucleation events to total particle concentrations on regional and global scales |
| VerfasserIn |
D. V. Spracklen, K. S. Carslaw, M. Kulmala  , V.-M. Kerminen, G. W. Mann, S.-L. Sihto |
| 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 ; 6, no. 12 ; Nr. 6, no. 12 (2006-12-18), S.5631-5648 |
| Datensatznummer |
250004208
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| Publikation (Nr.) |
 copernicus.org/acp-6-5631-2006.pdf |
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| Zusammenfassung |
| The contribution of boundary layer (BL) nucleation events to total
particle concentrations on the global scale has been studied by
including a new particle formation mechanism in a global aerosol
microphysics model. The mechanism is based on an analysis of extensive
observations of particle formation in the BL at a continental surface
site. It assumes that molecular clusters form at a rate proportional
to the gaseous sulfuric acid concentration to the power of 1. The
formation rate of 3 nm diameter observable particles is controlled by
the cluster formation rate and the existing particle surface area,
which acts to scavenge condensable gases and clusters during
growth. Modelled sulfuric acid vapour concentrations, particle
formation rates, growth rates, coagulation loss rates, peak particle
concentrations, and the daily timing of events in the global model
agree well with observations made during a 22-day period of March 2003
at the SMEAR II station in Hyytiälä, Finland. The nucleation
bursts produce total particle concentrations (>3 nm diameter) often
exceeding 104 cm−3, which are sustained for a period of
several hours around local midday. The predicted global distribution
of particle formation events broadly agrees with what is expected from
available observations. Over relatively clean remote continental
locations formation events can sustain mean total particle
concentrations up to a factor of 8 greater than those resulting from
anthropogenic sources of primary organic and black carbon
particles. However, in polluted continental regions anthropogenic
primary particles dominate particle number and formation events lead
to smaller enhancements of up to a factor of 2. Our results therefore
suggest that particle concentrations in remote continental regions are
dominated by nucleated particles while concentrations in polluted
continental regions are dominated by primary particles. The effect of
BL particle formation over tropical regions and the Amazon
is negligible. These first global particle formation simulations
reveal some interesting sensitivities. We show, for example, that
significant reductions in primary particle emissions may lead to an
increase in total particle concentration because of the coupling
between particle surface area and the rate of new particle
formation. This result suggests that changes in emissions may have a
complicated effect on global and regional aerosol properties. Overall,
our results show that new particle formation is a significant
component of the aerosol particle number budget. |
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