 |
| Titel |
Absorption coefficient of urban aerosol in Nanjing, west Yangtze River Delta, China |
| VerfasserIn |
B. L. Zhuang, T. J. Wang, J. Liu, Y. Ma, C. Q. Yin, S. Li, M. Xie, Y. Han, J. L. Zhu, X. Q. Yang, C. B. Fu |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1680-7316
|
| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 15, no. 23 ; Nr. 15, no. 23 (2015-12-10), S.13633-13646 |
| Datensatznummer |
250120216
|
| Publikation (Nr.) |
 copernicus.org/acp-15-13633-2015.pdf |
|
|
|
|
|
| Zusammenfassung |
| Absorbing aerosols can significantly modulate short-wave solar
radiation in the atmosphere, affecting regional and global climate. The aerosol
absorption coefficient (AAC) is an indicator that assesses the impact of
absorbing aerosols on radiative forcing. In this study, the near-surface AAC
and absorption Ångström exponent (AAE) in the urban area of Nanjing, China, are
characterized on the basis of measurements in 2012 and 2013 using the
seven-channel Aethalometer (model AE-31, Magee Scientific, USA). The AAC is
estimated with direct and indirect corrections, which result in consistent
temporal variations and magnitudes of AAC at 532 nm. The mean AAC at 532 nm
is about 43.23 ± 28.13 M m−1 in the urban area of Nanjing, which is much lower
than that in Pearl River Delta and the same as in rural areas
(Lin'an) in Yangtze River Delta. The AAC in the urban area of Nanjing shows strong
seasonality (diurnal variations); it is high in cold seasons (at rush hour) and
low in summer (in the afternoon). It also shows synoptic and quasi-2-week
cycles in response to weather systems. Its frequency distribution follows a
typical log-normal pattern. The 532 nm AAC ranging from 15 to 65 M m−1
dominates, accounting for more than 72 % of the total data samples in the
entire study period. Frequent high pollution episodes, such as those
observed in June 2012 and in winter 2013, greatly enhanced AAC and altered
its temporal variations and frequency distributions. These episodes are
mostly due to local emissions and regional pollution. Air masses flowing from
northern China to Nanjing can sometimes be highly polluted and lead to high
AAC at the site. AAE at 660/470 nm from the Schmid correction (Schmid et
al., 2006) is about 1.56, which might be more reasonable than from the
Weingartner correction (Weingartner et al., 2003). Low AAEs mainly occur in
summer, likely due to high relative humidity (RH) in the season. AAC
increases with increasing AAE at a fixed aerosol loading. The RH–AAC
relationship is more complex. Overall, AAC peaks at RH values of around 40 %
(1.3 < AAE < 1.6), 65 % (AAE < 1.3 and
AAE > 1.6), and 80 % (1.3 < AAE < 1.6). |
| |
|
| Teil von |
|
|
|
|
|
|
|
|