Optical, microphysical and physico-chemical properties of aerosols using in situ and remote sensing measurements in Athens Metropolitan and the Eastern Mediterranean Area [article]

Stergios Vratolis, National Technological University Of Athens, National Technological University Of Athens
2020
The main objective of this Ph.D. Thesis was to study the concentration, physical properties, and chemical composition of aerosols and their contribution to cloud formation in the Eastern Mediterranean, with emphasis on the Athens Metropolitan Area, using in situ and remote sensing measurement techniques. Other objectives include the contribution to new methods to deduct properties of the atmospheric aerosol and the comparison of aerosol measurements conducted by in situ and remote sensing
more » ... emote sensing instruments. This Thesis is structured in five chapters. In Chapter 1, we present the physical, chemical and optical properties of aerosols, their impact on climate and health, and the factors affecting aerosol concentration in the study area. We also present the NTUA Raman Lidar (EOLE) and the operation principle of Wind Doppler Lidar. In Chapter 2, we introduce the current situation of aerosol particle number concentration in City-Centre Urban Background, Urban Background and Regional Background stations in Greece. Based on the diurnal variations and previous studies, main sources for the City-Centre Urban Background station that were identified are traffic (freshly emitted and aged) and the regional background concentration. Sources for the Urban Background stations include fresh traffic and nucleation, aged traffic and cooking, and the regional background concentration. The Regional Background station dominant sources are local aged sources (cooking and other sources related to tourism) and the regional background concentration. Size distribution modal analysis was applied to the particle number concentration data and the results were subsequently divided in clusters. If we make the assumption that the accumulation cluster identified at the Regional Background station corresponds to the transported from other areas particle fraction, and use the median number concentration from each cluster, we conclude that 18% of the particle number distribution is transported at the City-Centre Urban Background site, 37% at the Urban Background sites, and 59% at the Regional Background site. Based on the air mass origin clustering of the regional background concentration, we concluded that the regional particle number concentrations when air masses originate from the Mediterranean Sea is much lower than when they originate from the North-East and North-West direction. Etesian flow conditions were found to increase the regional background particle concen-24
doi:10.26240/heal.ntua.17600 fatcat:ni6xbha2zzg2picdtobp76fbqa