Combined Characterization of Airborne Saharan Dust above Sofia, Bulgaria, during Blocking-Pattern Conditioned Dust Episode in February 2021

Abstract

The wintertime outbreaks of Saharan dust, increasing in intensity and frequency over the last decade, have become an important component of the global dust cycle and a challenging issue in elucidating its feedback to the ongoing climate change. For their adequate monitoring and characterization, systematic multi-instrument observations and multi-aspect analyses of the distribution and properties of desert aerosols are required, covering the full duration of dust events. In this paper, we present observations of Saharan dust in the atmosphere above Sofia, Bulgaria, during a strong dust episode over the whole of Europe in February 2021, conditioned by a persistent blocking weather pattern over the Mediterranean basin, providing clear skies and constant measurement conditions. This study was accomplished using different remote sensing (lidar, satellite, and radiometric), in situ (particle analyzing), and modeling/forecasting methods and resources, using real measurements and data (re)analysis. A wide range of columnar and range/time-resolved optical, microphysical, physical, topological, and dynamical characteristics of the detected aerosols dominated by desert dust are obtained and profiled with increased accuracy and reliability by combining the applied approaches and instruments in terms of complementarity, calibration, and normalization. Vertical profiles of the aerosol/dust total and mode volume concentrations are presented and analyzed using the LIRIC-2 inversion code joining lidar and sun-photometer data. The results show that interactive combining and use of various relevant approaches, instruments, and data have a significant synergistic effect and potential for verifying and improving theoretical models aimed at complete aerosol/dust characterization.

Identification of Saharan-Dust Intrusions over Sofia, Bulgaria, Using Near-Ground PM10 and PM2.5 Mass Concentration Measurements

“…The above-discussed characteristic parameters and environmental conditions concerning the aerosol field over Sofia on 26 February 2021 reveal a mixed aerosol situation with MA and SD making up the coarse-particle-rich aerosol component. Let us note that 25 and 26 February 2021 were days of a dust flow drop in the middle of a period of a massive transport to Europe of Saharan dust (Hoshyaripour, 2021;Szczepanik et al, 2022;Peshev et al, 2023), whose influence on the aerosol situation and especially on the concentration of PM10 through sedimentation was noticeable.…”

“…Remote sensing of the atmosphere is carried out by the Aerosol Remote Sensing (ARS) Station at the Institute of Electronics of the Bulgarian Academy of Sciences (Peshev et al, 2022;Evgenieva et al, 2022;Peshev et al, 2023). The Station is located in the southeast part of Sofia City (42.…”

“…The photometer is installed on the roof of the Institute of Electronics' building at about 20 m above ground. It is automatically operating according to pre-defined scenarios and is annually calibrated following the AERONET protocols at AERONET-EUROPE operating within the ACTRIS Centre for Aerosol Remote Sensing at Laboratoire d'Optique Atmosphérique, Université de Lille, France (CARS-ASP-CNRS) (Evgenieva et al, 2022;Peshev et al, 2023). A more detailed description of the photometer operation and of the AERONET capabilities are given, e.g., in Holben et al (1998), Barreto et al (2016), Giles et al (2019), andSinyuk et al (2020).…”