Thick anthropogenic aerosol layers detected by LIDAR above Sofia Available to Purchase

In this work we present selected experimental results from lidar studies of the troposphere performed above Sofia, Bulgaria, during the summer of 2011. The ground-based measurements were carried out by a lidar equipped with a Nd:YAG laser operating at the wavelengths of 532 nm and 1064 nm. The lidar data are presented and analyzed in terms of calculated vertical atmospheric backscatter coefficient profiles and 2D color maps of the range-corrected lidar signals. They reveal that relatively thick (till 3.5-5 km) aerosol formations were observed over the urban areas. We used HYSPLIT (HYbrid Single-Particle Lagrangian Integrated Trajectory) backward trajectories and DREAM (Dust REgional Atmospheric Model) forecasts to analyze lidar profiles outlines and to characterize the phenomena observed. Analyzing the weather conditions we were able to explain the stable persistence of aerosols above the atmospheric boundary layer. As neither other aerosol sources (like fires, volcano eruption), nor dust transport from Sahara desert over the Balkans were forecast for the days of the measurements, our conclusion was that the relatively thick layers observed had been caused by anthropogenic aerosols produced from human activities and city’s traffic.