 |
| Titel |
Study of columnar aerosol size distribution in Hong Kong |
| VerfasserIn |
X. Yang, M. Wenig |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1680-7316
|
| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 9, no. 16 ; Nr. 9, no. 16 (2009-08-31), S.6175-6189 |
| Datensatznummer |
250007594
|
| Publikation (Nr.) |
 copernicus.org/acp-9-6175-2009.pdf |
|
|
|
|
|
| Zusammenfassung |
| This paper presents studies on columnar aerosol optical properties in Hong
Kong with focus on aerosol volume size distribution, which helps understand
local aerosol properties, variation, hygroscopic growth and coagulation.
Long-term ground measurements in the wet season in the years of 2002, 2003,
2004 and 2008 have been performed using a sun-sky radiometer. Data validation
made using MODIS and local AERONET shows agreement. A bimodal size
distribution is found with the fine mode centering at
~0.2 μm and coarse mode centering at
~3 μm respectively. The fine and coarse mode have close
volume concentrations of nearly 50% fraction in composing local aerosols.
Intercomparison of different years shows similar aerosol properties while a
small increase of fine mode aerosol could be observed. A systematic shift of
size distribution parameters is observed with different atmospheric
conditions, where higher aerosol loadings and Angstrom exponent correspond to
more fine mode aerosols. The fine mode is found to be more closely correlated
with this shift than the coarse mode. A higher fine mode volume fraction and
smaller median fine radius correspond to a larger Angstrom exponent. The fine
mode aerosol hygroscopic growth is one of the main mechanisms for such
systematic shifting. A third mode centering at ~1–2 μm
could be discovered under high aerosol loading and high fine mode aerosol
conditions. It becomes more pronounced with high aerosol optical depth and
larger Angstrom exponent. Investigation of its variation with corresponding
optical parameters and correlation with atmospheric conditions appears to
support the hypothesis that it is mainly due to the fine mode aerosol
hygroscopic growth and coagulation rather than the contribution from the
coarse mode. While the very humid environment facilitates the aerosol
hygroscopic growth, aerosol coagulation might further produce larger aerosols
under high fine aerosol conditions. The continental outflow with transported
aging aerosols and biomass burning might have also contributed to this
additional mode. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|