Quantitative effects of air pollution on regional daily global and diffuse solar radiation under clear sky conditions

Air pollution is one of the most important factors affecting the solar radiation reaching the earth’s surface under the clear (cloudless) sky conditions. In this work, six typical cities with serious pollution located in the north, northeast, eastern, central, southwest, and southern regions of China: Beijing, Shenyang, Shanghai, Wuhan, Wenjiang and Guangzhou were selected. The influence of air pollution on global and diffuse solar radiation (Rs and Rd) under clear sky condition was quantitatively analyzed, based on the historical daily meteorological data from January 2014 to December 2020. The results showed that the highest Rs attenuation ratio of the above six cities appeared in spring, autumn, winter, summer, autumn and winter, respectively. The largest Rd increment ratio of the six cities appeared in summer, spring, autumn, summer, autumn and spring, respectively. From 2014 to 2020, the relative attenuation of Rs caused by air pollution (AQI > 100) was largest in Beijing (6.03%), followed by Shanghai (4.21%), Wenjiang (4.15%), Shenyang (3.28%) and Wuhan (3.14%), while Guangzhou (1.32%) had the smallest relative attenuation. Additionally, the Rd relative increment was largest in Beijing (16.21%), followed by Shanghai (8.78%), Wenjiang (8.13%), Shenyang (7.76%) and Guangzhou (5.96%), while Wuhan (2.57%) had the smallest relative increment.