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| Titel |
Absorption and scattering properties of organic carbon versus sulfate dominant aerosols at Gosan climate observatory in Northeast Asia |
| VerfasserIn |
S. Lim, M. Lee, S.-W. Kim, S.-C. Yoon, G. Lee, Y. J. Lee |
| 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 ; 14, no. 15 ; Nr. 14, no. 15 (2014-08-05), S.7781-7793 |
| Datensatznummer |
250118922
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| Publikation (Nr.) |
 copernicus.org/acp-14-7781-2014.pdf |
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| Zusammenfassung |
| Carbonaceous and soluble ionic species of PM1.0 and PM10 were
measured along with the absorption and scattering properties and aerosol
number size distributions at Gosan Climate Observatory (GCO) from January to
September 2008. The daily averaged equivalent black carbon (EBC) measured as
aerosol absorption exhibited two types of spectral dependence with a
distinct maximum (peak) at either 370 nm or 880 nm, by which two subsets
were extracted and classified into the respective groups (370 and 880 nm).
The 370 nm group was distinguished by high organic carbon (OC) concentrations
relative to elemental carbon (EC) and sulfate, but sulfate was predominant
for the 880 nm group. The PM1.0 OC of the 370 nm group was mainly
composed of refractory and pyrolized components that correlated well with
PM1.0 EC1, referred to as char EC, which suggests biofuel and biomass
combustion as the source of these OC fractions, particularly during winter.
The scanning electron microscope (SEM) images and the number size
distributions implied that aerosols of the 370 nm group were externally
mixed upon transport in fast-moving air masses that passed through the
Beijing area in about one day. In contrast, the aerosols of the 880 nm group
were characterized by high sulfate concentrations, and seemed to be
internally mixed during slow transport over the Yellow Sea region over
approximately 2 to 4 days. The absorption and scattering coefficients
of the 880 nm group were noticeably higher compared to those of the 370 nm
group. The average absorption ångström exponent (AAE) was estimated
to be 1.29 and 1.0 for the 370 and 880 nm groups, respectively, in the
range 370–950 nm. These results demonstrated that the optical properties of
aerosols were intimately linked to chemical composition and mixing state,
characteristics determined both by source and atmospheric aging processes.
In OC dominant aerosols, absorption was enhanced in the UV region, which was
possibly due to refractory and pyrolized OC compounds. Under sulfate
dominant conditions, the sulfate coating on BC particles likely contributed
to the absorption of the longer visible light. Consequently, single
scattering albedo (SSA) was higher for the 880 nm group than for the 370 nm
group, emphasizing that the relative abundances of absorbing and scattering
constituents are also important in estimating the climate effect of
aerosols. |
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