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| Titel |
A global off-line model of size-resolved aerosol microphysics: I. Model development and prediction of aerosol properties |
| VerfasserIn |
D. V. Spracklen, K. J. Pringle, K. S. Carslaw, M. P. Chipperfield, G. W. Mann |
| 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 ; 5, no. 8 ; Nr. 5, no. 8 (2005-08-19), S.2227-2252 |
| Datensatznummer |
250003038
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| Publikation (Nr.) |
 copernicus.org/acp-5-2227-2005.pdf |
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| Zusammenfassung |
| A GLObal Model of Aerosol Processes (GLOMAP) has been developed as an
extension to the TOMCAT 3-D Eulerian off-line chemical transport
model. GLOMAP simulates the evolution of the global aerosol size
distribution using a sectional two-moment scheme and includes the
processes of aerosol nucleation, condensation, growth, coagulation,
wet and dry deposition and cloud processing. We describe the results
of a global simulation of sulfuric acid and sea spray aerosol. The
model captures features of the aerosol size distribution that are well
established from observations in the marine boundary layer and free
troposphere. Modelled condensation nuclei (CN>3nm) vary between
about 250–500 cm-3 in remote marine boundary layer regions
and are generally in good agreement with observations. Modelled
continental CN concentrations are lower than observed, which may be
due to lack of some primary aerosol sources or the neglect of
nucleation mechanisms other than binary homogeneous nucleation of
sulfuric acid-water particles. Remote marine CN concentrations
increase to around 2000–10 000 cm (at standard
temperature and pressure) in the upper troposphere, which agrees with
typical observed vertical profiles. Cloud condensation nuclei (CCN) at
0.2% supersaturation vary between about 1000 cm-3 in polluted
regions and between 10 and 500 cm-3 in the remote marine
boundary layer. New particle formation through sulfuric acid-water
binary nucleation occurs predominantly in the upper troposphere, but
the model results show that these particles contribute greatly to
aerosol concentrations in the marine boundary layer. For this
sulfur-sea salt system it is estimated that sea spray emissions
account for only ~10% of CCN in the tropical marine boundary
layer, but between 20 and 75% in the mid-latitude Southern Ocean.
In a run with only natural sulfate and sea salt emissions the global
mean surface CN concentration is more than 60% of that from a run
with 1985 anthropogenic sulfur emissions, although the natural
emissions comprise only 27% of total sulfur emissions. Southern
hemisphere marine boundary layer CN are more than 90% natural in
origin, while polluted continental CN are more than 90% anthropogenic
in origin, although these numbers will change when other anthropogenic
CN sources are included in the model. |
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