Saharan Dust Events Over the Northern Mediterranean: 4 Years of Measurements Over 4 Earlinet Stations

¹ Applied Mathematics and Physical Sciences, National Technical University of Athens, 15780, Greece
² Consiglio Nazionale delle Ricerche, Istituto di Metodologie per l’Analisi Ambientale, Tito Scalo, 85050, Italy.
³ Andalusian Institute for Earth System Research, 18006, Granada, Spain
⁴ Department of Applied Physics, University of Granada, 18071, Granada, Spain
⁵ Department of Civil Engineering and Geomatics, ERATOSTHENES Research Centre, Cyprus University of Technology, 3036, Limassol, Cyprus
⁶ Institute of Atmospheric Physics, Deutsches Zentrum für Luft- und Raumfahrt (DLR), Oberpfaffenhofen, 82234, Germany
⁷ Department of Physics, Kuwait University, P.O. Box 5969, Safat 13060, Kuwait

^* Email: soupiona.rania@gmail.com

Published online: 7 July 2020

Abstract

Four years (2014-2017) of observations of depolarization Raman Lidar systems of four EARLINET (European Aerosol research Lidar Network) stations [from West to East: Granada (Spain), Potenza (Italy), Athens (Greece) and Limassol (Cyprus)] were collected and used to a statistical analysis of Saharan dust events over Mediterranean basin.

In this study, emphasis is given to the consistency of the particle linear depolarization ratio (δ_p532), the extinction-to-backscatter ratio mentioned as Lidar Ratio (LR₅₃₂) and the Aerosol Optical Thickness (AOT₅₃₂) within the observed Saharan dust layers, corresponding to the visible range (532 nm). Geometrical properties and clusters of aerosol mixtures are also presented. Our clustering was based on previous classification by airborne High Spectral Resolution Lidar (HSRL) observations and was further supported by backward trajectory analysis. We found mean δ_p532 values of 0.24±0.05, 0.26±0.06, 0.28±0.05 and 0.28±0.04, mean LR₅₃₂ values of 52±8 sr, 51±9 sr, 52±9 sr and 49±6 sr, mean AOT₅₃₂ values of 0.40±0.31, 0.11±0.07, 0.12±0.10 and 0.32±0.17 and mean layer thicknesses of 3392±1458 m, 2150±1082 m, 1872±816 m and 1716±567 m for Granada, Potenza, Athens and Limassol respectively.

This work could assist in bridging the existing gaps related to the extensive and intensive dust aerosol properties over the Mediterranean and enriching the bibliography about mixed aerosol layers from different sources (e.g. dust and biomass burning (BB) aerosols, dust and urban/ industrial aerosols).