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| Titel |
Potential for a biogenic influence on cloud microphysics over the ocean: a correlation study with satellite-derived data |
| VerfasserIn |
A. Lana, R. Simó, S. M. Vallina, J. Dachs |
| 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 ; 12, no. 17 ; Nr. 12, no. 17 (2012-09-06), S.7977-7993 |
| Datensatznummer |
250011429
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| Publikation (Nr.) |
 copernicus.org/acp-12-7977-2012.pdf |
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| Zusammenfassung |
| Aerosols have a large potential to influence climate through their effects
on the microphysics and optical properties of clouds and, hence, on the
Earth's radiation budget. Aerosol–cloud interactions have been intensively
studied in polluted air, but the possibility that the marine biosphere plays
an important role in regulating cloud brightness in the pristine oceanic
atmosphere remains largely unexplored. We used 9 yr of global satellite
data and ocean climatologies to derive parameterizations of the temporal
variability of (a) production fluxes of sulfur aerosols formed by the
oxidation of the biogenic gas dimethylsulfide emitted from the sea surface;
(b) production fluxes of secondary organic aerosols from biogenic organic
volatiles; (c) emission fluxes of biogenic primary organic aerosols ejected
by wind action on sea surface; and (d) emission fluxes of sea salt also
lifted by the wind upon bubble bursting. Series of global monthly estimates
of these fluxes were correlated to series of potential cloud condensation
nuclei (CCN) numbers derived from satellite (MODIS). More detailed
comparisons among weekly series of estimated fluxes and satellite-derived
cloud droplet effective radius (re) data were conducted at locations
spread among polluted and clean regions of the oceanic atmosphere. The
outcome of the statistical analysis was that positive correlation to CCN
numbers and negative correlation to re were common at mid and high
latitude for sulfur and organic secondary aerosols, indicating both might be
important in seeding cloud droplet activation. Conversely, primary aerosols
(organic and sea salt) showed widespread positive correlations to CCN only
at low latitudes. Correlations to re were more variable, non-significant
or positive, suggesting that, despite contributing to large shares of the
marine aerosol mass, primary aerosols are not widespread major drivers of
the variability of cloud microphysics. Validation against ground
measurements pointed out that the parameterizations used captured fairly
well the variability of aerosol production fluxes in most cases, yet some
caution is warranted because there is room for further improvement,
particularly for primary organic aerosol. Uncertainties and synergies are
discussed, and recommendations of research needs are given. |
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