Effect of organic coatings on optical properties of black carbon aerosol: Insights from Mie theory based model simulations

Black carbon (BC), play a crucial role in climate change due to their significant impact on radiative forcing. This study investigates the influence of organic carbon (OC) coatings on the optical properties of BC aerosols using Mie theory-based calculations. We have examined a range of core diameters and coating thicknesses to assess changes in both absorption and scattering cross-sections. The results reveal that coatings consistently enhance both absorption and scattering properties, with the enhancement in scattering being higher in magnitude than enhancement in absorption. The study compares the optical properties of coated BC with that of OC particle showing that as the coating thickness increases, the optical behavior of the coated BC particle converges towards that of OC. The calculations for simple radiative forcing efficiency showed that as the coating on BC increases, its forcing efficiency decreases, implying that heavily coated BC may have a reduced radiative impact in the atmosphere.