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| Titel |
A global off-line model of size-resolved aerosol microphysics: II. Identification of key uncertainties |
| 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. 12 ; Nr. 5, no. 12 (2005-12-06), S.3233-3250 |
| Datensatznummer |
250003191
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| Publikation (Nr.) |
 copernicus.org/acp-5-3233-2005.pdf |
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| Zusammenfassung |
| We use the new GLOMAP model of global aerosol microphysics to
investigate the sensitivity of modelled sulfate and sea salt aerosol
properties to uncertainties in the driving microphysical processes and
compare these uncertainties with those associated with aerosol and
precursor gas emissions. Overall, we conclude that uncertainties in
microphysical processes have a larger effect on global sulfate and sea
salt derived condensation nuclei (CN) and cloud condensation nuclei
(CCN) concentrations than uncertainties in present-day sulfur
emissions. Our simulations suggest that uncertainties in predicted
sulfate and sea salt CCN abundances due to poorly constrained
microphysical processes are likely to be of a similar magnitude to
long-term changes in sulfate and sea salt CCN due to changes in
anthropogenic emissions. A microphysical treatment of the global
sulfate aerosol allows the uncertainty in climate-relevant aerosol
properties to be attributed to specific processes in a way that has
not been possible with simpler aerosol schemes. In particular we
conclude that: (1) changes in the binary H2SO4-H2O
nucleation rate and condensation rate of gaseous H2SO4 cause
a shift in the vertical location of the upper tropospheric CN layer by
as much as 3 km, while the shape of the CN profile is
essentially pre-served (2) uncertainties in the binary
H2SO4-H2O nucleation rate have a relatively insignificant
effect on marine boundary layer (MBL) aerosol properties; (3) emitting a
fraction of anthropogenic SO2 as particulates (to represent
production of sulfate particles in power plant plumes below the scale
of the model grid (which is of the order of 300 km)) has the
potential to change the global mean MBL sulfate-derived CN concentrations
by up to 72%, and changes of up to a factor 20
can occur in polluted continental regions; (4) predicted global mean
MBL sulfate and
sea salt CCN concentrations change by 10 to 60% when
several microphysical processes are changed within reasonable
uncertainty ranges; (5) sulfate and sea salt derived CCN
concentrations are particularly sensitive to primary particle
emissions, with global mean MBL sulfate and sea salt CCN changing by up to
27% and local concentrations over continental regions changing by more than 100% when the
percentage of anthropogenic
SO2 emitted as particulates is changed from 0 to
5%; (6) large changes in sea spray flux have insignificant effects on
global sulfate aerosol except when the mass accommodation coefficient
of sulfuric acid on the salt particles is set unrealistically low. |
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