scholarly journals Optical-microphysical properties of Saharan dust aerosols and composition relationship using a multi-wavelength Raman lidar, in situ sensors and modelling: a case study analysis

2011 ◽  
Vol 11 (9) ◽  
pp. 25473-25516 ◽  
Author(s):  
A. Papayannis ◽  
R. E. Mamouri ◽  
V. Amiridis ◽  
E. Remoundaki ◽  
G. Tsaknakis ◽  
...  
Keyword(s):  
Refractive Index ◽  
Saharan Dust ◽  
Dust Particles ◽  
Raman Lidar ◽  
Dust Event ◽  
Aerosol Composition ◽  
Data Set ◽  
Optical Extinction ◽  
Microphysical Properties

Abstract. A strong Saharan dust event occurred over the city of Athens, Greece (37.9° N, 23.6° E) between 27 March and 3 April 2009. The BSC-DREAM8b model was used to forecast the dust event and to provide the vertical profiles of the aerosol concentration. Due to mixture of dust particles with low clouds during most of the reported period, the dust event could be followed by the National Technical University of Athens (NTUA) 6-wavelength Raman lidar system only during the unclouded day of 2 April 2009. The lidar data obtained were used to retrieve the vertical profile of the optical (extinction and backscatter coefficients) properties of aerosols in the troposphere. Additionally, a retrieval technique representing dust as a mixture of spheres and spheroids was used to derive the mean aerosol dust microphysical properties (mean and effective radius, number, surface and volume density, and mean refractive index) in different layers between 1.8 and 3.5 km a.s.l. The final data set of the aerosol optical and microphysical properties along with the water vapor profiles obtained by Raman lidar were incorporated into the ISORROPIA II model to infer an in situ aerosol composition consistent with the retrieved refractive index values. PM10 concentrations levels, PM10 composition results and SEM-EDX (Scanning Electron Microscope-Energy Dispersive X-ray) analysis results on sizes and mineralogy of particles from samples during the Saharan dust transport event were used to evaluate the retrieval.

scholarly journals Optical-microphysical properties of Saharan dust aerosols and composition relationship using a multi-wavelength Raman lidar, in situ sensors and modelling: a case study analysis

2012 ◽  
Vol 12 (9) ◽  
pp. 4011-4032 ◽  
Author(s):  
A. Papayannis ◽  
R. E. Mamouri ◽  
V. Amiridis ◽  
E. Remoundaki ◽  
G. Tsaknakis ◽  
...  
Keyword(s):  
Refractive Index ◽  
Saharan Dust ◽  
Dust Particles ◽  
Raman Lidar ◽  
Dust Event ◽  
Aerosol Composition ◽  
Data Set ◽  
Microphysical Properties ◽  
The Mean ◽  
532 Nm

Abstract. A strong Saharan dust event that occurred over the city of Athens, Greece (37.9° N, 23.6° E) between 27 March and 3 April 2009 was followed by a synergy of three instruments: a 6-wavelength Raman lidar, a CIMEL sun-sky radiometer and the MODIS sensor. The BSC-DREAM model was used to forecast the dust event and to simulate the vertical profiles of the aerosol concentration. Due to mixture of dust particles with low clouds during most of the reported period, the dust event could be followed by the lidar only during the cloud-free day of 2 April 2009. The lidar data obtained were used to retrieve the vertical profile of the optical (extinction and backscatter coefficients) properties of aerosols in the troposphere. The aerosol optical depth (AOD) values derived from the CIMEL ranged from 0.33–0.91 (355 nm) to 0.18–0.60 (532 nm), while the lidar ratio (LR) values retrieved from the Raman lidar ranged within 75–100 sr (355 nm) and 45–75 sr (532 nm). Inside a selected dust layer region, between 1.8 and 3.5 km height, mean LR values were 83 ± 7 and 54 ± 7 sr, at 355 and 532 nm, respectively, while the Ångström-backscatter-related (ABR355/532) and Ångström-extinction-related (AER355/532) were found larger than 1 (1.17 ± 0.08 and 1.11 ± 0.02, respectively), indicating mixing of dust with other particles. Additionally, a retrieval technique representing dust as a mixture of spheres and spheroids was used to derive the mean aerosol microphysical properties (mean and effective radius, number, surface and volume density, and mean refractive index) inside the selected atmospheric layers. Thus, the mean value of the retrieved refractive index was found to be 1.49( ± 0.10) + 0.007( ± 0.007)i, and that of the effective radiuses was 0.30 ± 0.18 μm. The final data set of the aerosol optical and microphysical properties along with the water vapor profiles obtained by Raman lidar were incorporated into the ISORROPIA II model to provide a possible aerosol composition consistent with the retrieved refractive index values. Thus, the inferred chemical properties showed 12–40% of dust content, sulfate composition of 16–60%, and organic carbon content of 15–64%, indicating a possible mixing of dust with haze and smoke. PM10 concentrations levels, PM10 composition results and SEM-EDX (Scanning Electron Microscope-Energy Dispersive X-ray) analysis results on sizes and mineralogy of particles from samples during the Saharan dust transport event were used to evaluate the retrieval.

scholarly journals Multi-wavelength Raman lidar, sunphotometric and aircraft measurements in combination with inversion models for the estimation of the aerosol optical and physico-chemical properties over Athens, Greece

2012 ◽  
Vol 5 (1) ◽  
pp. 589-625
Author(s):  
R. E. Mamouri ◽  
A. Papayannis ◽  
V. Amiridis ◽  
D. Müller ◽  
P. Kokkalis ◽  
...  
Keyword(s):  
Water Vapor ◽  
Chemical Properties ◽  
Urban Site ◽  
Aircraft Measurements ◽  
Raman Lidar ◽  
Lidar System ◽  
Aerosol Composition ◽  
Microphysical Properties ◽  
Multi Wavelength

Abstract. A novel procedure has been developed to retrieve, simultaneously, the optical, microphysical and chemical properties of tropospheric aerosols with a multi-wavelength Raman lidar system in the troposphere over an urban site (Athens, Greece: 37.9° N, 23.6° E, 200 m a.s.l.) using data obtained during the European Space Agency (ESA) THERMOPOLIS project which took place between 15–31 July 2009 over the Greater Athens Area (GAA). We selected to apply our procedure for a case study of intense aerosol layers occurred on 20–21 July 2009. The National Technical University of Athens (NTUA) EOLE 6-wavelength Raman lidar system has been used to provide the vertical profiles of the optical properties of aerosols (extinction and backscatter coefficients, lidar ratio) and the water vapor mixing ratio. An inversion algorithm was used to derive the mean aerosol microphysical properties (mean effective radius – reff), single-scattering albedo (ω) and mean complex refractive index (m) at selected heights in the 2–3 km height region. We found that reff was 0.3–0.4 μm, ω at 532 nm ranged from 0.63 to 0.88 and m ranged from 1.45 + 0.015i to 1.56 + 0.05i, in good accordance with in situ aircraft measurements. The final data set of the aerosol microphysical properties along with the water vapor and temperature profiles were incorporated into the ISORROPIA model to infer an in situ aerosol composition consistent with the retrieved m and ω values. The retrieved aerosol chemical composition in the 2–3 km height region gave a variable range of sulfate (0–60%) and organic carbon (OC) content (0–50%), although the OC content increased (up to 50%) and the sulfate content dropped (up to 30%) around 3 km height; in connection with the retrieved low ω value (0.63), indicates the presence of absorbing biomass burning smoke mixed with urban haze. Finally, the retrieved aerosol microphysical properties were compared with column-integrated sunphotometer data.

scholarly journals Retrieval of microphysical dust particle properties from SALTRACE lidar observations: Case studies

2020 ◽  
Author(s):  
Stefanos Samaras ◽  
Christine Böckmann ◽  
Moritz Haarig ◽  
Albert Ansmann ◽  
Adrian Walser ◽  
...  
Keyword(s):  
Long Range ◽  
Software Tool ◽  
Total Surface Area ◽  
Saharan Dust ◽  
Radiation Budget ◽  
Dust Particles ◽  
Long Range Transport ◽  
Raman Lidar ◽  
Microphysical Properties ◽  
Range Transport

Abstract. Saharan dust is a major natural atmospheric aerosol component with significant impact on the Earth radiation budget. In this work we determine the microphysical properties of dust particles after a long-range transport over the Atlantic Ocean, using input from three depolarization channels of a multi-wavelength polarization Raman lidar. The measurements were performed at Barbados in the framework of the Saharan Aerosol Long-Range Transport and Aerosol–Cloud-Interaction Experiment (SALTRACE) in the summers of 2013 and 2014. The microphysical retrievals are performed with the software tool SphInX (Spheroidal Inversion Experiments) which uses regularization for the inversion process and a new two-dimensional (2-D) extension of the Mie model approximating dust with spheroids. The method allows us to simultaneously retrieve shape- and size-dependent particle distributions. Because dust particles are mostly non-spherical this software tool fills the gap in estimating the non-spherical particle fraction. Two cases measured on 10 July 2013 and 20 June 2014 are discussed. 2-D radius-bimodal shape-size distribution are retrieved. The ratio of spherical-to-non-spherical contributions to the particle number concentration was found to be about 3/7. A volume-weighted effective aspect ratio of 1.1 was obtained, indicating slightly prolate particles. The total effective radius for the two cases in the preselected radius range from 0.01–2.2 μm was found to be, on average, 0.75 μm. The stronger dust event (10 July 2013) showed about 24 % higher values for the total surface-area and volume concentration. Finally, we compare our results with the ones from the polarization lidar-photometer networking (POLIPHON) method and ground-based photometers as well as with airborne in situ particle counters. Considering all differences in these independent approaches, we find a qualitatively good agreement between the different results and a consistent description of the dust cases. Such an extensive comparison is a novel and fruitful exercise and corroborates that the mathematical retrieval based on Raman lidar data of particle backscattering, extinction, and depolarization is a powerful tool even in the case of dust particles.

scholarly journals Multi-wavelength Raman lidar, sun photometric and aircraft measurements in combination with inversion models for the estimation of the aerosol optical and physico-chemical properties over Athens, Greece

2012 ◽  
Vol 5 (7) ◽  
pp. 1793-1808 ◽  
Author(s):  
R. E. Mamouri ◽  
A. Papayannis ◽  
V. Amiridis ◽  
D. Müller ◽  
P. Kokkalis ◽  
...  
Keyword(s):  
Water Vapor ◽  
Chemical Properties ◽  
Urban Site ◽  
Aircraft Measurements ◽  
Raman Lidar ◽  
Lidar System ◽  
Aerosol Composition ◽  
Microphysical Properties ◽  
Multi Wavelength

Abstract. A novel procedure has been developed to retrieve, simultaneously, the optical, microphysical and chemical properties of tropospheric aerosols with a multi-wavelength Raman lidar system in the troposphere over an urban site (Athens, Greece: 37.9° N, 23.6° E, 200 m a.s.l.) using data obtained during the European Space Agency (ESA) THERMOPOLIS project, which took place between 15–31 July 2009 over the Greater Athens Area (GAA). We selected to apply our procedure for a case study of intense aerosol layers that occurred on 20–21 July 2009. The National Technical University of Athens (NTUA) EOLE 6-wavelength Raman lidar system has been used to provide the vertical profiles of the optical properties of aerosols (extinction and backscatter coefficients, lidar ratio) and the water vapor mixing ratio. An inversion algorithm was used to derive the mean aerosol microphysical properties (mean effective radius (reff), single-scattering albedo ω) and mean complex refractive index (m)) at selected heights in the 2–3 km height region. We found that reff was 0.14–0.4 (±0.14) μm, ω was 0.63–0.88 (±0.08) (at 532 nm) and m ranged from 1.44 (±0.10) + 0.01 (±0.01)i to 1.55 (±0.12) + 0.06 (±0.02)i, in good agreement (only for the reff values) with in situ aircraft measurements. The water vapor and temperature profiles were incorporated into the ISORROPIA II model to propose a possible in situ aerosol composition consistent with the retrieved m and ω values. The retrieved aerosol chemical composition in the 2–3 km height region gave a variable range of sulfate (0–60%) and organic carbon (OC) content (0–50%), although the OC content increased (up to 50%) and the sulfate content dropped (up to 30%) around 3 km height; the retrieved low ω value (0.63), indicates the presence of absorbing biomass burning smoke mixed with urban haze. Finally, the retrieved aerosol microphysical properties were compared with column-integrated sun photometer CIMEL data.

scholarly journals A comparative study of aerosol microphysical properties retrieved from ground-based remote sensing and aircraft in situ measurements during a Saharan dust event

2016 ◽  
Vol 9 (3) ◽  
pp. 1113-1133 ◽  
Author(s):  
María José Granados-Muñoz ◽  
Juan Antonio Bravo-Aranda ◽  
Darrel Baumgardner ◽  
Juan Luis Guerrero-Rascado ◽  
Daniel Pérez-Ramírez ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Volume Concentration ◽  
Mineral Dust ◽  
In Situ Measurements ◽  
Published Data ◽  
Dust Event ◽  
Data Set ◽  
Passive Remote Sensing ◽  
Microphysical Properties

Abstract. In this work we present an analysis of aerosol microphysical properties during a mineral dust event taking advantage of the combination of different state-of-the-art retrieval techniques applied to active and passive remote sensing measurements and the evaluation of some of those techniques using independent data acquired from in situ aircraft measurements. Data were collected in a field campaign performed during a mineral dust outbreak at the Granada, Spain, experimental site (37.16° N, 3.61° W, 680 m a.s.l.) on 27 June 2011. Column-integrated properties are provided by sun- and star-photometry, which allows for a continuous evaluation of the mineral dust optical properties during both day and nighttime. Both the linear estimation and AERONET (Aerosol Robotic Network) inversion algorithms are applied for the retrieval of the column-integrated microphysical particle properties. In addition, vertically resolved microphysical properties are obtained from a multi-wavelength Raman lidar system included in EARLINET (European Aerosol Research Lidar Network), by using both LIRIC (Lidar Radiometer Inversion Code) algorithm during daytime and an algorithm applied to the Raman measurements based on the regularization technique during nighttime. LIRIC retrievals reveal the presence of dust layers between 3 and 5 km a.s.l. with volume concentrations of the coarse spheroid mode up to 60 µm3 cm−3. The combined use of the regularization and LIRIC methods reveals the night-to-day evolution of the vertical structure of the mineral dust microphysical properties and offers complementary information to that from column-integrated variables retrieved from passive remote sensing. Additionally, lidar depolarization profiles and LIRIC retrieved volume concentration are compared with aircraft in situ measurements. This study presents for the first time a comparison of the total volume concentration retrieved with LIRIC with independent in situ measurements, obtaining agreement within the estimated uncertainties for both methods and quite good agreement for the vertical distribution of the aerosol layers. Regarding the depolarization, the first published data set of the CAS-POL for polarization ratios is presented here and qualitatively compared with the lidar technique.

scholarly journals Vertical profiles, optical and microphysical properties of Saharan dust layers determined by a ship-borne lidar

2003 ◽  
Vol 3 (5) ◽  
pp. 1353-1364 ◽  
Author(s):  
F. Immler ◽  
O. Schrems
Keyword(s):  
Saharan Dust ◽  
Dust Particles ◽  
Backscatter Coefficient ◽  
North African ◽  
Data Set ◽  
New Approach ◽  
Air Masses ◽  
Microphysical Properties ◽  
Lidar Measurements ◽  
North African Origin

Abstract. A unique data set of ship-borne lidar measurements of Saharan dust layers above the Atlantic ocean has been collected aboard the research vessel Polarstern with a mobile Aerosol Raman Lidar (MARL) during the LIMPIDO-campaign in June 2000. Extended Saharan dust layers have been observed in the region between 8.5º N and 34º N in an altitude range between 2 and 6 km. The continental, North African origin of the probed air masses is confirmed by 8-day backward trajectories. The Saharan dust is characterized by an optical depth in the range of 0.1 and 0.3, a depolarization around 10% and high lidar ratios of 45 sr at 532 nm and 75 sr at 355 nm. The backscattering by the dust particles at the UV-wavelength is relatively weak, resulting in a negative color index. From the measured optical properties the effective radius and the refractive index of the dust particles are derived using a new approach based on Mie Theory and non-spherical scattering calculations. The low backscatter coefficient observed at 355 nm is due to significant absorption which increases with decreasing wavelength. This finding agrees very well with results from satellite and sun photometer measurements. The effective radii decrease from about 3 mm at the base to 0.6 mm at the top of the dust plumes. The non-spherical shapes of the dust particles are responsible for the high values of the lidar ratios.

scholarly journals Vertical profiles, optical and microphysical properties of Saharan dust layers determined by a ship-borne lidar

2003 ◽  
Vol 3 (3) ◽  
pp. 2707-2737 ◽  
Author(s):  
F. Immler ◽  
O. Schrems
Keyword(s):  
Saharan Dust ◽  
Dust Particles ◽  
Backscatter Coefficient ◽  
North African ◽  
Data Set ◽  
New Approach ◽  
Air Masses ◽  
Microphysical Properties ◽  
Lidar Measurements ◽  
North African Origin

Abstract. A unique data set of ship-borne lidar measurements of Saharan dust layers above the Atlantic ocean has been collected aboard the research vessel Polarstern with a mobile Aerosol Raman Lidar (MARL) during the LIMPIDO-campaign in June 2000. Extended Saharan dust layers have been observed in the region between 8.5° N and 34° N in an altitude range between 2 and 6 km. The continental, North African origin of the probed air masses is confirmed by 8-day backward trajectories. The Saharan dust is characterized by an optical depth in the range of 0.1 and 0.3, a depolarization around 10\\% and high lidar ratios of 45 sr at 532 nm and 75 sr at 355 nm. The backscattering by the dust particles at the UV-wavelength is relatively weak, resulting in a negative color index. From the measured optical properties the effective radius and the refractive index of the dust particles are derived using a new approach based on Mie Theory and non-spherical scattering calculations. The low backscatter coefficient observed at 355 nm is due to significant absorption which increases with decreasing wavelength. This finding agrees very well with results from satellite and sun photometer measurements. The effective radii decrease from about 3 mm base to 0.6 mm at the top of the dust plumes. The non-spherical shapes of the dust particles are responsible for the high values of the lidar ratios.

scholarly journals Evaluation of the Lidar/Radiometer Inversion Code (LIRIC) to determine microphysical properties of volcanic and desert dust

2013 ◽  
Vol 6 (1) ◽  
pp. 911-948 ◽  
Author(s):  
J. Wagner ◽  
A. Ansmann ◽  
U. Wandinger ◽  
P. Seifert ◽  
A. Schwarz ◽  
...  
Keyword(s):  
Theoretical Background ◽  
Saharan Dust ◽  
Dust Particles ◽  
Raman Lidar ◽  
Particle Volume ◽  
Microphysical Properties ◽  
Fine Mode ◽  
Lidar Ratio ◽  
Lidar Observations ◽  
Good Agreement

Abstract. The Lidar/Radiometer Inversion Code (LIRIC) combines the multiwavelength lidar technique with sun-sky photometry and allows us to retrieve vertical profiles of particle optical and microphysical properties, separately for fine-mode and coarse-mode particles. After a brief presentation of the theoretical background, we evaluate the potential of LIRIC to retrieve the optical and microphysical properties of irregularly shaped dust particles. The method is applied to two very different aerosol scenarios, a strong Saharan dust outbreak towards central Europe and an Eyjafjallajökull volcanic dust event. LIRIC profiles of particle volume and mass concentrations are compared with results obtained with the polarization-lidar-based POLIPHON method. LIRIC profiles of optical properties such as particle backscatter coefficients, lidar ratio, Ångström exponent, and particle depolarization ratio are compared with direct Raman lidar observations. Good agreement between the different results are found for most of the retrieval products.

scholarly journals Aerosol optical and microphysical retrievals from a hybrid multiwavelength lidar data set – DISCOVER-AQ 2011

2014 ◽  
Vol 7 (9) ◽  
pp. 3095-3112 ◽  
Author(s):  
P. Sawamura ◽  
D. Müller ◽  
R. M. Hoff ◽  
C. A. Hostetler ◽  
R. A. Ferrare ◽  
...  
Keyword(s):  
Remote Sensing ◽  
In Situ Measurements ◽  
Index Of Refraction ◽  
High Spectral Resolution ◽  
Lidar Data ◽  
Data Set ◽  
Microphysical Properties ◽  
Lidar Measurements ◽  
Multiwavelength Lidar

Abstract. Retrievals of aerosol microphysical properties (effective radius, volume and surface-area concentrations) and aerosol optical properties (complex index of refraction and single-scattering albedo) were obtained from a hybrid multiwavelength lidar data set for the first time. In July 2011, in the Baltimore–Washington DC region, synergistic profiling of optical and microphysical properties of aerosols with both airborne (in situ and remote sensing) and ground-based remote sensing systems was performed during the first deployment of DISCOVER-AQ. The hybrid multiwavelength lidar data set combines ground-based elastic backscatter lidar measurements at 355 nm with airborne High-Spectral-Resolution Lidar (HSRL) measurements at 532 nm and elastic backscatter lidar measurements at 1064 nm that were obtained less than 5 km apart from each other. This was the first study in which optical and microphysical retrievals from lidar were obtained during the day and directly compared to AERONET and in situ measurements for 11 cases. Good agreement was observed between lidar and AERONET retrievals. Larger discrepancies were observed between lidar retrievals and in situ measurements obtained by the aircraft and aerosol hygroscopic effects are believed to be the main factor in such discrepancies.

scholarly journals Lidar Measuremnt on Dust Transport from the Saharan Desert to the Iran Plateau

2020 ◽  
Vol 237 ◽  
pp. 02020
Author(s):  
Hossein Panahifar ◽  
Ruhollah Moradhaseli ◽  
Hadi Bourzoie ◽  
Mahdi Gholami ◽  
Hamid Reza Khalesifard
Keyword(s):  
Trajectory Analysis ◽  
Saharan Dust ◽  
Dust Particles ◽  
Raman Lidar ◽  
Dust Layer ◽  
Mean Values ◽  
Dust Transport ◽  
Lidar Ratio ◽  
532 Nm ◽  
Iran Plateau

Optical properties of long-range Saharan dust particles transported to the Iran Plateau have been investigated. The results were derived from the measurements of a dual-wavelength Depolarized backscatter/Raman lidar and a Cimel CE318-2 sunphotometer. Observations were performed in Zanjan, Northwest Iran. The backward trajectory analysis show that the lofted dust plumes come from the Saharan desert and travel along Mediterranean Sea and Turkey toward Iran. The lidar ratio within the lofted dust layer has been found with mean values of 50 sr at 532 nm. For the depolarization ratio, mean values of 25% have been found.

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