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| Titel |
Elemental carbon in snow at Changbai Mountain, northeastern China: concentrations, scavenging ratios, and dry deposition velocities |
| VerfasserIn |
Z. W. Wang, J. C. Gallet, C. A. Pedersen, X. S. Zhang, J. Ström, Z. J. Ci |
| 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. 2 ; Nr. 14, no. 2 (2014-01-22), S.629-640 |
| Datensatznummer |
250118296
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| Publikation (Nr.) |
 copernicus.org/acp-14-629-2014.pdf |
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| Zusammenfassung |
| Light-absorbing aerosol – particularly elemental carbon
(EC) – while mixed with snow and ice is an important climate driver from the
enhanced absorption of solar radiation. Currently, considerable efforts are
being made to estimate its radiative forcing on a global scale, but several
uncertainties remain, particularly those regarding its deposition processes.
In this study, concurrent measurements of EC in air and snow are performed
for three years (2009–2012) at Changbai station, northeastern China. The
scavenging ratio and the wet- and dry-deposition fluxes of EC over the snow
surface are estimated. The mean EC concentration in the surface snow is 1000 ± 1500 ng g−1,
ranging from 7 to 7640 ng g−1. The
mean value of the scavenging ratio of EC by snow is 140 ± 100, with a
median value of 150, which is smaller than that reported in Arctic areas. A
non-rimed snow process is a significant factor in interpreting differences
with Arctic areas. Wet-deposition fluxes of EC are estimated to be 0.47 ± 0.37 μg cm−2
month−1 on average over the three snow
seasons studied. Dry deposition is more than five times higher, with an
average of 2.65 ± 1.93 μg cm−2 month−1; however, only
winter period estimation is possible (December–February). During winter in
Changbai, 87% of EC in snow is estimated to be due to dry deposition,
with a mean dry deposition velocity of 6.44 × 10−3 m s−1
and median of 8.14 × 10−3 m s−1. Finally, the
calculation of the radiative effect shows that 500 ng g−1 of
dry-deposited EC to a snow surface absorbs three times more incoming solar
energy than the same mass mixed in the snow through wet deposition.
Deposition processes of an EC-containing snow surface are, therefore,
crucial to estimate its radiative forcing better, particularly in
northeastern China, where local emission strongly influences the level and gradient of EC
in the snowpack, and snow-covered areas are cold and dry due to the
atmospheric general circulation. Furthermore, this study builds on the
knowledge to characterize the conditions in the snow-laden Chinese
rural areas better as well as to constrain transport of EC to the Arctic better. |
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