Solar attenuation by aerosols: An overview

One of the most important factors affecting the attenuation of solar radiation reaching the earth's surface under cloudless sky conditions is the presence of aerosol particles. A direct measurement of the aerosol transmittance is not possible due to the strong influence of the other atmospheric components. Thus the extinction caused by the atmospheric aerosol can be calculated only indirectly using fundamental physical techniques. This work provides an overview of the effect of aerosols on solar radiation budget by considering two common turbidity parameters including the Linke turbidity factor T _L and Ångström turbidity coefficients β and α. Total extinction of solar radiation due to the absorption and the scattering caused by the atmospheric aerosol accounts for 10-20% for zero zenith angle. The influence of aerosol on radiation passing through the atmosphere cannot be neglected, especially in urban or industrialized areas. The attenuation of solar radiation through a real atmosphere versus that through a clean dry atmosphere gives an indication of the atmospheric turbidity.