Effect of Water Insoluble Component on Angstrom Exponent and Radiative Forcing of Continental Polluted Aerosols

Abstract

In this paper, the optical properties of continental polluted aerosols were extracted from optical properties of Aerosols and cloud (OPAC) software at a spectral range of (0.24-0.80)µm ultraviolet to visible region and at eight relative humidity (0%,50%,70%,80%,90%,95%,98% &99%) to determine the effect of water insoluble component. The data were obtained by varying default concentration number of water insoluble component in the simulation software (OPAC). The optical parameters extracted were used to calculate the radiative forcing by the approach of Chylek and Wong, the Angstrom exponent (α), turbidity (β) and curvature (α2) using regression analysis. From the results obtained it was observed that α which determined the particle size distribution is greater than 1.0 at (0%-95%) RHs and it signifies that fine accumulation mode is the most dominant but at deliquescence points (98%-99%) RHs α is less than1.0 and this show the present of coarse mode. The curvature α2 which gives additional information of particle mode distributions was negative at all RHs indicating the dominance of fine mode particles. The optical depth of the
atmospheric aerosols were determined for each model and analyzed graphically, the results have shown the clear decrease in size with increase in wavelength, but increases with increase in RHs. The turbidity β increase with increases in concentration number of water insoluble signifies the increases in aerosol loading which show decrease in visibility of the atmosphere. The analysis further shows that these aerosols have monomodal type of particle distributions.