Classification of aerosol types in mega-city of Lahore (Pakistan) using ground-based remote sensing

This study was aimed at classifying the aerosol types and assessing their temporal distribution in the atmosphere of Lahore. For this purpose, we utilized the particle linear depolarization ratio (PLDR) and single scattering albedo (SSA) from Aerosol Robotic Network (AERONET) version 3 inversion products. Datasets from AERONET stationed at Lahore were computed to obtain results. Based on the dust ratio (R_d) (obtained from SSA and PLDR) aerosols were classified into pure dust (PD), pollution aerosols: non-absorbing (NA), weakly absorbing (WA), moderately absorbing (MA), and strongly absorbing (SA) aerosols, and mixtures: pollution-dominated mixture (PDM), and dust dominated-mixture (DDM). The highest aerosol density was in regions with higher angstrom exponent (AE) values. The atmosphere of Lahore is dominated by 65% pollution aerosols (29% PDM and 34% pollution aerosols). DDM (dust-dominated mixtures) prevails mostly in the summer and spring seasons, while PD or DDM is observed in very low quantities in the cold season (only in pre- and post-winter season months). The winter season months are highly polluted with 80% pure pollution aerosol dominance. Mostly low PLDR values are observed in the atmosphere of Lahore indicating dominance by pollution aerosols associated with anthropogenic pollution sources.