Ground-based observation of aerosol optical properties in Lanzhou, China
YU Xingna , ZHU Bin , FAN Shuxian , YIN Yan , BU Xiaoli
DOI:
Received December 02, 2008,Revised April 04, 2009, Accepted , Available online
Volume 21,2009,Pages 1519-1524
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Aerosol optical properties from August 2006 to July 2007 were obtained from ground-based and sky radiance measurements in Semi-
Arid Climate and Environment Observatory of Lanzhou University (SACOL), China. High aerosol optical thickness (AOT) associated
with low ?ngstr¨om exponent ( ) was mainly observed in spring, which was consistent with the seasonal dust production from Hexi
Corridor. The maximum monthly average value of AOT 0.56 occurred in March of 2007, which was two times larger than the minimum
value of 0.28 in October of 2006. Approximately 60% of the AOT ranged between 0.3 and 0.5, and nearly 93% of value varied from
0.1 to 0.8, which occurred in spring. The significant correlation between aerosol properties and water vapor content was not observed.
The aerosol volume size distribution can be characterized by the bimodal logarithm normal structure: fine mode (r < 0.6 m) and coarse
mode (r > 0.6 m). Aerosols in spring of SACOL were dominated by large particles with the volume concentration ratio of coarse to
fine modes being 7.85. The average values of asymmetry factor (g) in the wavelength range 440–1020 nm were found to be 0.71, 0.67,
0.67 and 0.69 in spring, summer, autumn and winter, respectively.
