 |
| Titel |
Single particle characterization of black carbon aerosols at a tropospheric alpine site in Switzerland |
| VerfasserIn |
D. Liu, M. Flynn, M. Gysel, A. Targino, I. Crawford, K. Bower, T. Choularton, Z. Jurányi, M. Steinbacher, C. Hüglin, J. Curtius, M. Kampus, A. Petzold, E. Weingärtner, U. Baltensperger, H. Coe |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1680-7316
|
| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 10, no. 15 ; Nr. 10, no. 15 (2010-08-09), S.7389-7407 |
| Datensatznummer |
250008693
|
| Publikation (Nr.) |
 copernicus.org/acp-10-7389-2010.pdf |
|
|
|
|
|
| Zusammenfassung |
| The refractory black carbon (rBC) mass, size distribution (190–720 nm) and
mixing state in sub-micron aerosols were characterized from late February to
March 2007 using a single particle incandescence method at the high alpine
research station Jungfraujoch (JFJ), Switzerland (46.33° N, 7.59° E,
3580 m a.s.l.). JFJ is a ground based location, which is at times exposed to
continental free tropospheric air. A median mass absorption coefficient
(MAC) of 10.2±3.2 m2 g−1 at λ=630 nm was derived by
comparing single particle incandescence measurements of black carbon mass
with continuous measurements of absorption coefficient. This value is
comparable with other estimates at this location. The aerosols measured at
the site were mostly well mixed and aged during transportation via the free
troposphere. Pollutant sources were traced by air mass back trajectories,
trace gases concentrations and the mass loading of rBC. In southeasterly
wind directions, mixed or convective weather types provided the potential to
vent polluted boundary layer air from the southern Alpine area and
industrial northern Italy, delivering enhanced rBC mass loading and CN
concentrations to the JFJ. The aerosol loadings at this site were also
significantly influenced by precipitation, which led to the removal of rBC
from the atmosphere. Precipitation events were shown to remove about 65%
of the rBC mass from the free tropospheric background reducing the mean
loading from 13±5 ng m−3 to 6±2 ng m−3(corrected to
standard temperature and pressure). Overall, 40±15% of the observed
rBC particles within the detectable size range were mixed with large amounts
of non-refractory materials present as a thick coating. The growth of
particle size into the accumulation mode was positively linked with the
degree of rBC mixing, suggesting the important role of condensable materials
in increasing particle size and leading to enhanced internal mixing of these
materials with rBC. It is the first time that BC mass, size distribution and
mixing state are reported in the free troposphere over Europe. These ground
based measurements also provide the first temporal study of rBC in the
European free troposphere quantitatively measured by single particle
methods. At the present time there is only limited information of BC and its
mixing state in the free troposphere, especially above Europe. The results
reported in this paper provide an important constraint on modelled
representation of BC. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|