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| Titel |
Evaluation of a global aerosol microphysics model against size-resolved particle statistics in the marine atmosphere |
| VerfasserIn |
D. V. Spracklen, K. J. Pringle, K. S. Carslaw, G. W. Mann, P. Manktelow, J. Heintzenberg |
| 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 ; 7, no. 8 ; Nr. 7, no. 8 (2007-04-26), S.2073-2090 |
| Datensatznummer |
250004917
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| Publikation (Nr.) |
 copernicus.org/acp-7-2073-2007.pdf |
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| Zusammenfassung |
| A statistical synthesis of marine aerosol measurements from
experiments in four different oceans is used to evaluate a global
aerosol microphysics model (GLOMAP). We compare the model against
observed size resolved particle concentrations, probability
distributions, and the temporal persistence of different size
particles. We attempt to explain the observed sub-micrometre size
distributions in terms of sulfate and sea spray and quantify the
possible contributions of anthropogenic sulfate and carbonaceous
material to the number and mass distribution. The model predicts a
bimodal size distribution that agrees well with observations as a
grand average over all regions, but there are large regional
differences. Notably, observed Aitken mode number concentrations are
more than a factor 10 higher than in the model for the N Atlantic but
a factor 7 lower than the model in the NW Pacific. We also find that
modelled Aitken mode and accumulation mode geometric mean diameters
are generally smaller in the model by 10–30%. Comparison with
observed free tropospheric Aitken mode distributions suggests that the
model underpredicts growth of these particles during descent to the
marine boundary layer (MBL). Recent observations of a substantial organic component of free
tropospheric aerosol could explain this discrepancy. We find that
anthropogenic continental material makes a substantial contribution to
N Atlantic MBL aerosol, with typically 60–90% of sulfate across the
particle size range coming from anthropogenic sources, even if we
analyse air that has spent an average of >120 h away from
land. However, anthropogenic primary black carbon and organic carbon
particles (at the emission size and quantity assumed here) do not
explain the large discrepancies in Aitken mode number. Several
explanations for the discrepancy are suggested. The lack of lower
atmospheric particle formation in the model may explain low N Atlantic
particle concentrations. However, the observed and modelled particle
persistence at Cape Grim in the Southern Ocean, does not reveal a
diurnal cycle consistent with a photochemically driven local particle
source. We also show that a physically based cloud drop activation
scheme better explains the observed change in accumulation mode
geometric mean diameter with particle number. |
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