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| Titel |
Black carbon aerosol in winter northeastern Qinghai–Tibetan Plateau, China: the source, mixing state and optical property |
| VerfasserIn |
Q. Y. Wang, R.-J. Huang, J. J. Cao, X. X. Tie, H. Y. Ni, Y. Q. Zhou, Y. M. Han, T. F. Hu, C. S. Zhu, T. Feng, N. Li, J. D. Li |
| 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 ; 15, no. 22 ; Nr. 15, no. 22 (2015-11-25), S.13059-13069 |
| Datensatznummer |
250120183
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| Publikation (Nr.) |
 copernicus.org/acp-15-13059-2015.pdf |
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| Zusammenfassung |
| Black carbon (BC) aerosol at high altitudes of the Qinghai–Tibetan Plateau has
potential effects on the regional climate and hydrological cycle. An
intensive measurement campaign was conducted at Qinghai Lake (~ 3200 m
above sea level) at the edge of the northeastern Qinghai–Tibetan Plateau
during winter using a ground-based single particle soot photometer (SP2) and
a photoacoustic extinctiometer (PAX). The average concentration of refractory
BC (rBC) and number fraction of coated rBC were found to be
160 ± 190 ng m−3 and 59 % for the entire campaign,
respectively. Significant enhancements of rBC loadings and number fraction of
coated rBC were observed during a pollution episode, with an average value of
390 ng m−3 and 65 %, respectively. The mass size distribution of
rBC particles showed log-normal distribution, with a peak diameter of
~ 187 nm regardless of the pollution level. Five-day backward
trajectory analysis suggests that the air masses from north India contributed
to the increased rBC loadings during the campaign. The potential source
contribution function (PSCF) model combined with the fire counts map further
proves that biomass burning from north India is an important potential source
influencing the northeastern Qinghai–Tibetan Plateau during the pollution
episode. The rBC mass absorption cross section (MACrBC) at λ
= 532 nm was slightly larger in clean days (14.9 m2 g−1) than
during the pollution episode (9.3 m2 g−1), likely due to the effects
of brown carbon and the uncertainty of the MACrBC calculation. The
MACrBC was positively correlated with number fraction of coated rBC
during the pollution episode with an increasing rate of
0.18 (m2 g−1) %−1. The number fraction of coated rBC
particles showed positive correlation with light absorption, suggesting that
the increase of coated rBC particles will enhance the light absorption.
Compared to rBC mass concentration, rBC mixing sate is more important in
determining absorption during the pollution episode, estimated from the same
percentage-wise increment of either rBC mass concentration or the number
fraction of coated rBC. The estimated BC direct radiative forcing was
+0.93 W m−2 for the pollution episode, which is 2 times larger than that
in clean days. Our study provides insight into the potential climatic impacts
of rBC aerosol transported to the Qinghai–Tibetan Plateau from south Asian
regions, and is also useful for future modeling studies. |
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