Analysis of Aerosol Optical Depth from Sun Photometer at Shouxian, China

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.

Automated summary

In this study, two cloud screening methods were used to process sun photometer measurements in Shouxian from March 2020 to April 2021. The results show that there is a clear diurnal variation in AOD, with an overall average of 0.48 and significant seasonal differences. The single scattering albedo in Shouxian is higher compared to other regions, indicating strong scattering and weak aerosol absorption.