This work numerically evaluates urban aerosol optical properties using OPAC 4.0 across 0.4–0.8 µm wavelengths, focusing on insoluble (INSO), soot (SOOT), and water-soluble (WASO) components at 0% and 50% relative humidity (RH). Fifteen aerosol models were developed with five concentration gradients per component. The Ångström exponent ( ᾳ a ) systematically decreases with increasing INSO (1.376-1.273) and increases with SOOT (1.376-1.386) and WASO (1.376-1.433). A critical non-linear hygroscopic response was identified: α increases from 0% to 50% RH at low WASO concentrations but decreases at high concentrations due to hygroscopic saturation and coarse-mode transition. Phase function forward scattering enhances with RH, most pronounced for WASO (1.626-1.785). MODIS validation across ten countries shows OPAC-derived ᾳa  (1.27-1.43) matching anthropogenically influenced regions (Germany ᾳa =1.27, Ethiopia ᾳa =1.45), while extreme values (South Africa ᾳa =2.39; Egypt ᾳa =0.12) represent aerosol types beyond OPAC's urban scope.