We use two cloud screening methods-the clustering method and the multiplet method-to
process the measurements of a sun photometer from March 2020 to April 2021 in Shouxian.
The aerosol optical depth (AOD) and Angstrom parameters alpha and beta are retrieved;
variation characteristics and single scattering albedo are studied. The results show
that: (1) The fitting coefficient of AOD retrieved by the two methods is 0.921, and
the changing trend is consistent. The clustering method has fewer effective data points
and days, reducing the overall average of AOD by 0.0542 (500 nm). (2) Diurnal variation
of AOD can be divided into flat type, convex type, and concave type. Concave type
and convex type occurred the most frequently, whereas flat type the least. (3) During
observation, the overall average of AOD is 0.48, which is relatively high. Among them,
AOD had a winter maximum (0.70), autumn and spring next (0.54 and 0.40), and a summer
minimum (0.26). The variation trend of AOD and beta is highly consistent, and the
monthly mean of alpha is between 0.69 and 1.61, concerning mainly continental and
urban aerosols. (4) Compared with others, the single scattering albedo in Shouxian
is higher, reflecting strong scattering and weak aerosol absorption.
