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Abstract: This work describes a field measurement of the aerosol optical properties and water-soluble inorganic (WSI) ion concentrations in aerosols at 1h resolution from 2 April to 5 May 2010 in urban Shanghai. The average scattering coefficient at 532nm (αs,532) is 102±75Mm−1, much lower than values of Beijng and Guangzhou although four pollution events occurred during this field campaign. The single scattering albedo (ω) is 0.70 at 532nm, which is considerably low, indicating higher relative abundance of light absorbing soot in Shanghai. The similar patterns of diurnal cycles of αs,532 and NH4 + concentration suggested that formation of secondary inorganic aerosol is one of dominant elements to decide diurnal cycles of optical properties of aerosol in Shanghai. Both αs,532 and absorption coefficient at 532nm (αa,532) have linear relationship with mass concentration of SO4 2−, NO3 −, Cl− and NH4 +. The concentration of NH4 + presents best linear relationship with αs,532. The mass scattering cross section is 15.7m2 g−1 for SO4 2−. There is obvious dependence between the aerosol optical properties and the wind directions. The aerosol loading from west is much higher than those from Northeast (NE) and Southeast (SE) due to pollution parcels from Zhejiang and Jiangsu province. The decreasing rate of ω following the increase of αa,532 is highest during NE wind period, followed by that during SE and then West, suggesting a higher mass fraction of soot in aerosol during NE wind. [Copyright &y& Elsevier]

In the present work, we propose a novel algorithm to determine the scattering coefficient of OA by evaluating the relationships of the MSEs for primary organic aerosol (POA) and secondary organic aerosol (SOA) with their mass concentrations at three distinct sites, i.e. an urban site, a rural site, and a background site in China. Our results showed that the MSEs for POA and SOA increased rapidly as a function of mass concentration in low mass loading. While the increasing rate declined after a threshold of mass loading of 50 μg/m3 for POA, and 15 μg/m3 for SOA, respectively. The dry scattering coefficients of submicron particles (PM 1) were reconstructed based on the algorithm for POA and SOA scattering coefficient and further verified by using multi-site data. The calculated dry scattering coefficients using our reconstructing algorithm have good consistency with the measured ones, with the high correlation and small deviation in Shanghai (R2 = 0.98; deviations: 2.9%) and Dezhou (R2 = 0.90; deviations: 4.7%), indicating that our algorithms for OA and PM 1 are applicable to predict the scattering coefficient of OA and Submicron particle (PM 1) in China. Image 1 • The variations of MSEs for POA and SOA were investigated. • The MSEs for POA and SOA increased rapidly as a function of mass concentration in low mass loading. • MSEs declined at the threshold of mass loading were 50 and 15 μg/m3 for POA and SOA, respectively. • The algorithm for scattering coefficient of ambient OA were reconstructed. [ABSTRACT FROM AUTHOR]