Saharan Dust Loads over Sofia, Bulgaria: Lidar Observations on Winter and Spring Dust Events

Abstract

Aerosols have significant impacts on the climate, ecosystems, and human health. Sahara Desert is the largest source of natural mineral aerosols (dust) on Earth. Enormous amounts of Saharan particulate matter are frequently transported to Europe through advection of warm air masses, being typical for spring and summer. Over the last years, winter Saharan dust load events have also been reported for various locations over Europe, including Sofia. In this work, we give a description of lidar observations of atmospheric aerosols present above Sofia, Bulgaria, during episodes of Saharan dust intrusions in periods of minimum (in winter) and maximum (in spring) activity of dust transport to the region. Measurements were conducted in February and April 2021, with the two aerosol channels (at 532 nm and 1064 nm) of the Nd:YAG-laser based lidar. Aerosol/dust layering and optical and microphysical properties are characterized. Colourmaps of the vertical aerosol distribution and its temporal dynamics were presented. Time-averaged vertical profiles of the aerosol backscatter coefficients and corresponding backscatter-related Ångström exponents were retrieved and analyzed. The Saharan origin of the aerosols detected was identified using online available air/dust tracking and mapping web resources. Results obtained show that the considered here dust load events have affected significantly both the structure and aerosol composition of the local troposphere.