Fengsheng Zhao¹, Yongbo Tan², Zhanqing Li^1,3, Changsong Gai⁴

¹ State Key Laboratory of Earth Surface Processes and Resource Ecology, GCESS, Beijing Normal University, Beijing, China;

² School of Atmospheric Physics, Nanjing University of Information Science and Technology, Nanjing, China;

³ Department of Atmospheric and Oceanic Sciences, Cooperative Institute for Climate Studies, University of Maryland, College Park, Maryland, USA;

⁴ Chongqing Meteorological Bureau, Chongqing, China.

 

Abstract: The Sun photometer is widely used to retrieve aerosol optical depth (AOD). In this study, the effect of atmospheric forward scattering on the measurement of direct solar irradiance is analyzed. In most cases, this effect can be safely neglected. However, in the case of heavy dust loading, errors in AOD derived from Sun photometer measurements can be significant which warrants a correction of the forward scattering to derive accurate values of AOD. An algorithm is presented for such a correction.