TY - JOUR A1 - Soupiona, Ourania A1 - Samaras, Stefanos A1 - Ortiz-Amezcua, Pablo A1 - Böckmann, Christine A1 - Papayannis, Alexandros D. A1 - Moreira, Gregori De Arruda A1 - Benavent-Oltra, Jose Antonio A1 - Guerrero-Rascado, Juan Luis A1 - Bedoya-Velásquez, Andres Esteban A1 - Olmo-Reyes, Francisco José A1 - Román, Roberto A1 - Kokkalis, Panagiotis A1 - Mylonaki, Maria A1 - Alados-Arboledas, Lucas A1 - Papanikolaou, Christina Anna A1 - Foskinis, Romanos T1 - Retrieval of optical and microphysical properties of transported Saharan dust over Athens and Granada based on multi-wavelength Raman lidar measurements: Study of the mixing processes JF - Atmospheric environment : air pollution ; emissions, transport and dispersion, transformation, deposition effects, micrometeorology, urban atmosphere, global atmosphere N2 - In this paper we extract the aerosol microphysical properties for a collection of mineral dust cases measured by multi-wavelength depolarization Raman lidar systems located at the National Technical University of Athens (NTUA, Athens, Greece) and the Andalusian Institute for Earth System Research (IISTA-CEAMA, Granada, Spain). The lidar-based retrievals were carried out with the Spheroidal Inversion eXperiments software tool (SphInX) developed at the University of Potsdam (Germany). The software uses regularized inversion of a two-dimensional enhancement of the Mie model based on the spheroid-particle approximation with the aspect ratio determining the particle shape. The selection of the cases was based on the transport time from the source regions to the measuring sites. The aerosol optical depth as measured by AERONET ranged from 0.27 to 0.54 (at 500 nm) depending on the intensity of each event. Our analysis showed the hourly mean particle linear depolarization ratio and particle lidar ratio values at 532 nm ranging from 11 to 34% and from 42 to 79 sr respectively, depending on the mixing status, the corresponding air mass pathways and their transport time. Cases with shorter transport time showed good agreement in terms of the optical and SphInX-retrieved microphysical properties between Athens and Granada providing a complex refractive index value equal to 1.4 + 0.004i. On the other hand, the results for cases with higher transport time deviated from the aforementioned ones as well as from each other, providing, in particular, an imaginary part of the refractive index ranging from 0.002 to 0.005. Reconstructions of two-dimensional shape-size distributions for each selected layer showed that the dominant effective particle shape was prolate with diverse spherical contributions. The retrieved volume concentrations reflect overall the intensity of the episodes. Y1 - 2019 U6 - https://doi.org/10.1016/j.atmosenv.2019.116824 SN - 1352-2310 SN - 1873-2844 VL - 214 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Samaras, Stefanos A1 - Nicolae, Doina A1 - Böckmann, Christine A1 - Vasilescu, Jeni A1 - Binietoglou, Ioannis A1 - Labzovskii, Lev A1 - Toanca, Florica A1 - Papayannis, Alexandros T1 - Using Raman-lidar-based regularized microphysical retrievals and Aerosol Mass Spectrometer measurements for the characterization of biomass burning aerosols JF - Journal of computational physics N2 - In this work we extract the microphysical properties of aerosols for a collection of measurement cases with low volume depolarization ratio originating from fire sources captured by the Raman lidar located at the National Institute of Optoelectronics (INOE) in Bucharest. Our algorithm was tested not only for pure smoke but also for mixed smoke and urban aerosols of variable age and growth. Applying a sensitivity analysis on initial parameter settings of our retrieval code was proved vital for producing semi-automatized retrievals with a hybrid regularization method developed at the Institute of Mathematics of Potsdam University. A direct quantitative comparison of the retrieved microphysical properties with measurements from a Compact Time of Flight Aerosol Mass Spectrometer (CToF-AMS) is used to validate our algorithm. Microphysical retrievals performed with sun photometer data are also used to explore our results. Focusing on the fine mode we observed remarkable similarities between the retrieved size distribution and the one measured by the AMS. More complicated atmospheric structures and the factor of absorption appear to depend more on particle radius being subject to variation. A good correlation was found between the aerosol effective radius and particle age, using the ratio of lidar ratios (LR: aerosol extinction to backscatter ratios) as an indicator for the latter. Finally, the dependence on relative humidity of aerosol effective radii measured on the ground and within the layers aloft show similar patterns. (C) 2015 Elsevier Inc. All rights reserved. KW - Aerosols KW - Microphysical properties KW - Lidar KW - AMS KW - AERONET Y1 - 2015 U6 - https://doi.org/10.1016/j.jcp.2015.06.045 SN - 0021-9991 SN - 1090-2716 VL - 299 SP - 156 EP - 174 PB - Elsevier CY - San Diego ER - TY - JOUR A1 - Ortiz-Amezcua, Pablo A1 - Guerrero-Rascado, Juan Luis A1 - Jose Granados-Munoz, Maria A1 - Benavent-Oltra, Jose Antonio A1 - Böckmann, Christine A1 - Samaras, Stefanos A1 - Stachlewska, Iwona Sylwia A1 - Janicka, Lucja A1 - Baars, Holger A1 - Bohlmann, Stephanie A1 - Alados-Arboledas, Lucas T1 - Microphysical characterization of long-range transported biomass burning particles from North America at three EARLINET stations JF - Atmospheric Chemistry and Physics N2 - Strong events of long-range transported biomass burning aerosol were detected during July 2013 at three EARLINET (European Aerosol Research Lidar Network) stations, namely Granada (Spain), Leipzig (Germany) and Warsaw (Poland). Satellite observations from MODIS (Moderate Resolution Imaging Spectroradiometer) and CALIOP (Cloud-Aerosol Lidar with Orthogonal Polarization) instruments, as well as modeling tools such as HYSPLIT (Hybrid Single-Particle Lagrangian Integrated Trajectory) and NAAPS (Navy Aerosol Analysis and Prediction System), have been used to estimate the sources and transport paths of those North American forest fire smoke particles. A multiwavelength Raman lidar technique was applied to obtain vertically resolved particle optical properties, and further inversion of those properties with a regularization algorithm allowed for retrieving microphysical information on the studied particles. The results highlight the presence of smoke layers of 1-2 km thickness, located at about 5 km a.s.l. altitude over Granada and Leipzig and around 2.5 km a.s.l. at Warsaw. These layers were intense, as they accounted for more than 30% of the total AOD (aerosol optical depth) in all cases, and presented optical and microphysical features typical for different aging degrees: color ratio of lidar ratios (LR532/LR355) around 2, alpha-related angstrom exponents of less than 1, effective radii of 0.3 mu m and large values of single scattering albedos (SSA), nearly spectrally independent. The intensive microphysical properties were compared with columnar retrievals form co-located AERONET (Aerosol Robotic Network) stations. The intensity of the layers was also characterized in terms of particle volume concentration, and then an experimental relationship between this magnitude and the particle extinction coefficient was established. Y1 - 2017 U6 - https://doi.org/10.5194/acp-17-5931-2017 SN - 1680-7316 SN - 1680-7324 VL - 17 SP - 5931 EP - 5946 PB - Copernicus CY - Göttingen ER -