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| Titel |
Characterization of light-absorbing carbon particles at three altitudes in East Asian outflow by transmission electron microscopy |
| VerfasserIn |
J. Zhu, P. A. Crozier, J. R. Anderson |
| 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 ; 13, no. 13 ; Nr. 13, no. 13 (2013-07-04), S.6359-6371 |
| Datensatznummer |
250018738
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| Publikation (Nr.) |
 copernicus.org/acp-13-6359-2013.pdf |
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| Zusammenfassung |
| The morphology, microstructure, and composition of the submicron fraction of
individual light-absorbing carbon (LAC) particles collected by research
aircraft during the ACE-Asia (Asian Pacific Regional Aerosol Characterization
Experiment) project above the Yellow Sea at altitudes of 120, 450 and 1500 m
are investigated by transmission electron microscopy (TEM), and energy
dispersive X-ray spectroscopy (EDS). Two types of carbonaceous particles,
small spherule soot with graphitic spherules and amorphous carbonaceous
spheres (brown carbon), are found at all altitudes in high concentration. For
soot particles, emphasis of the study is on the component subparticles
(spherules). The nanoscopic structures of the small spherule soot show no
significant difference at three altitudes although the size distribution of
primary spherules showed that 70% of the total volume lies in the ranges
30–50, 50–85 and 30–50 nm, respectively. For the amorphous carbonaceous
spheres, 70% of the total volume from three altitudes lies in the range
200–350, 160–470 and 150–320 nm, respectively. Within the size fraction
studied (submicron, with most particles in the range 50 to 500 nm) the
number concentration ratios of the amorphous carbonaceous spheres to primary
spherules in soot at altitudes of 120, 450 and 1500 m are about 1, 1.5 and
10, respectively and their volume ratios are about 260, 50 and 1400. Lower
relative concentrations of large spherule soot with intermediate graphitic
structure were observed at 120 m. Also, low relative number concentrations
of carbon cenospheres were observed at 120 and 1500 m. A key result of the
study is that in vertically stratified outflow from East Asia, the character
of LAC may have strong variance with altitude thus resulting in optical
characteristics that vary with altitude. Also, apparent "aging" of LAC
deduced from samples at multiple ground stations may instead reflect
differences in the original carbon aerosols. |
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