The aerosol situation over Sofia, Bulgaria, on 3 October 2023 was investigated on the basis of lidar and ceilometer data on the atmospheric aerosol stratification, and of sun/sky/lunar photometer-measurement-based AERONET data on the aerosol optical and microphysical characteristics. Validation data were used as well from satellite observations of fire outbreaks around the world, air mass transport and dispersion models, desert-dust spread forecasting models, and weather information. The data obtained on the optical and microphysical aerosol properties, the extreme fire activity worldwide, and the long-range (mainly from Canada and less often from northern and central Africa) and shorter-range (mainly from Europe and Atlantic Ocean) backward trajectories, showed that the situation on 3 October 2023 was rather an aerosol event with prevailing content of aged and fresh biomass burning smoke, urban and continental aerosol, and possibly a lower content of marine aerosol and Saharan dust.
Evgenieva et al. (Thu,) studied this question.