Sensitivity of Contribution of Organic Aerosol on Aerosol Optical Properties in Refractive Index and Hygroscopicity

In this study, the sensitivity of organic aerosol on aerosol optical properties is conducted. Both the refractive index of Organic aerosol as well as hygroscopicity was considered. Based on the filter based monthly averaged sampling measurement data at the intensive observation sites in Seoul, Korea, the contribution of each composition on the aerosol optical properties were estimated. The aerosol optical properties are simulated by combining aerosol dynamic model for polydispersed aerosol with optical properties model using Mie theory. The obtained optical properties such as extinction, scattering and absorption coefficient were calculated AERONET Aerosol Optical Thickness measurement data. In order to estimate contribution of the light absorption and hygroscopicity properties of Organic Aerosol on the aerosol optical properties, the sensitivity test was conducted with different imaginary refractive index and organic aerosol hygroscopic growth factor. The results show that mass extinction and absorption efficiency increases linearly as imaginary refractive index increase, which means one can estimate the mass absorption efficiency of organic aerosol using the linear regression as a function of imaginary refractive index. The results also show that mass extinction and absorption efficiency decreases as hygroscopic factor of organic aerosol increases. The contribution of organic aerosol on the mass extinction efficiency, however, depends on the chemical composition of other aerosol mixture.