Aerosol investigation during the Arctic Haze season 2018Optical, Microphysical and Radiative properties

In this work, optical and microphysical properties of Arctic aerosol as well as their radiative impact are investigated. Air-borne Lidar observations along with ground-based measurements are evaluated for the Arctic Haze season of 2018. Aerosol abundance as inferred from particle backscatter was typical for this period of the year, with nearly spherical particles. However, the inversion of microphysical properties yielded high Refractive Index (RI) together with low Single-Scattering Albedo (SSA), suggesting absorbing particles, which are not typical for the Arctic Haze period. A fitted lognormal volume distribution revealed a fine mode with effective radius (reff) of 0.23 μm and a coarse mode with reff=0.75 μm. The total aerosol forcing at ground level was negative according to observations and radiative transfer simulations.