Closure method development for extinction coefficients and chemical compositions of aerosol by mobile measurement in Shanghai

Mobile measurements were conducted in Shanghai in autumn 2020 to explore the chemical composition and optical properties of PM2.5. The measurement period was categorized into clean days (PM2.5 <= 35 mu g m(-3)) and non-clean days (PM2.5 > 35 mu g m(-3)) to comprehensively understand the impact of local emissions from urban and industrial areas. The average concentration of PM2.5 during the mobile measurements period was 28.5 mu g m(-3), with organic matter, nitrate, sulfate, and ammonium accounting for an average of 40.67% (11.5 mu g m(-3)), 20.5% (5.8 mu g m(-3)), 13.4% (3.8 mu g m(-3)), and 13.4% (3.8 mu g m(-3)), respectively. The average extinction coefficients were 85.5 and 112.1 Mm-1 in urban and industrial areas on clean days and 309.1 and 472.9 Mm(-1) in urban and industrial areas on non-clean days, respectively. Different interagency monitoring of protected visual environments (IMPROVE) algorithms were used to reconstruct the extinction coefficients using the measured datasets. The existing IMPROVE algorithms were adaptable exclusively on non-clean days. Finally, a novel equation was constructed and verified to determine extinction coefficients using mobile measurements.