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| Titel |
The Pagami Creek smoke plume after long-range transport to the upper troposphere over Europe – aerosol properties and black carbon mixing state |
| VerfasserIn |
F. Dahlkötter, M. Gysel, D. Sauer, A. Minikin, R. Baumann, P. Seifert, A. Ansmann, M. Fromm, C. Voigt, B. Weinzierl |
| 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. 12 ; Nr. 14, no. 12 (2014-06-20), S.6111-6137 |
| Datensatznummer |
250118824
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| Publikation (Nr.) |
 copernicus.org/acp-14-6111-2014.pdf |
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| Zusammenfassung |
| During the CONCERT 2011 field experiment with the DLR research aircraft
Falcon, an enhanced aerosol layer with particle linear depolarization ratios
of 6–8% at 532 nm was observed at altitudes above 10 km over
northeast Germany on 16 September 2011. Dispersion simulations with HYSPILT
suggest that the elevated aerosol layer originated from the Pagami Creek
forest fire in Minnesota, USA, which caused pyro-convective uplift of
particles and gases. The 3–4 day-old smoke plume had high total refractory
black carbon (rBC) mass concentrations of 0.03–0.35 μg m−3
at standard temperature and pressure (STP) with rBC mass equivalent diameter
predominantly smaller than 130 nm. Assuming a core-shell particle structure,
the BC cores exhibit very thick (median: 105–136 nm) BC-free coatings. A
large fraction of the BC-containing particles disintegrated into a BC-free
fragment and a BC fragment while passing through the laser beam of the Single
Particle Soot Photometer (SP2). In this study, the disintegration is a result
of very thick coatings around the BC cores. This is in contrast to a previous
study in a forest-fire plume, where it was hypothesized to be a result of BC
cores being attached to a BC-free particle. For the high-altitude forest-fire
aerosol layer observed in this study, increased mass specific
light-absorption cross sections of BC can be expected due to the very thick
coatings around the BC cores, while this would not be the case for the
attached-type morphology. We estimate the BC mass import from the Pagami
Creek forest fire into the upper troposphere/lower stratosphere (UTLS) region
(best estimate: 25 Mg rBC). A comparison to black carbon emission rates from
aviation underlines the importance of pyro-convection on the BC load in the
UTLS region. Our study provides detailed information on the microphysics and
the mixing state of BC in the forest-fire aerosol layer in the upper
troposphere that can be used to better understand and investigate the
radiative impact of such upper tropospheric aerosol layers. |
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