Effect of urban submicron particles on single scattering albedo: the case study of high pollution event

•Primary organic aerosol had higher mass absorption cross-section values•Under high pollution, SSA depends on submicron PM and BC ratio•BrC did not show a significant impact on SSA under high pollution In order to reduce uncertainties in estimation of aerosol radiative forcing, multi-parameter field observational studies are crucial. In this study, alterations of single scattering albedo (SSA), aerosol chemical composition, microphysical and optical characteristics (aerosol light scattering and absorption coefficients, absorption and scattering Ångström exponents, symmetry parameter, aging, size, aerosol liquid water content and other) were analyzed during residential heating season (from 10th October to 1st November 2014) in urban environment in Lithuania. In addition, a high concentration event was observed. High resolution and complex field measurements enabled evaluation of different aerosol parameters as drivers of SSA alterations under increased pollution levels. During the event, an evident input of not photochemically aged and small particles was observed together with increased levels of both black and brown carbon (BC and BrC, respectively). It was found that mainly PM1/BC ratio had the highest influence on SSA values. At the beginning of the event due to increased levels of light scattering particles, SSA remained unchanged (0.95). Meantime at the second half of the event scavenging of these particles and emissions of light absorbing primary aerosol resulted in SSA decreased to 0.86.