scholarly journals GARRLiC and LIRIC: strengths and limitations for the characterization of dust and marine particles along with their mixtures

2017 ◽  
Vol 10 (12) ◽  
pp. 4995-5016 ◽  
Author(s):  
Alexandra Tsekeri ◽  
Anton Lopatin ◽  
Vassilis Amiridis ◽  
Eleni Marinou ◽  
Julia Igloffstein ◽  
...  
Keyword(s):  
Eastern Mediterranean ◽  
Saharan Dust ◽  
Concentration Profiles ◽  
Mixing Conditions ◽  
Microphysical Properties ◽  
Marine Particles ◽  
Ground Based Lidar ◽  
Photometric Measurements

Abstract. The Generalized Aerosol Retrieval from Radiometer and Lidar Combined data algorithm (GARRLiC) and the LIdar-Radiometer Inversion Code (LIRIC) provide the opportunity to study the aerosol vertical distribution by combining ground-based lidar and sun-photometric measurements. Here, we utilize the capabilities of both algorithms for the characterization of Saharan dust and marine particles, along with their mixtures, in the south-eastern Mediterranean during the CHARacterization of Aerosol mixtures of Dust and Marine origin Experiment (CHARADMExp). Three case studies are presented, focusing on dust-dominated, marine-dominated and dust–marine mixing conditions. GARRLiC and LIRIC achieve a satisfactory characterization for the dust-dominated case in terms of particle microphysical properties and concentration profiles. The marine-dominated and the mixture cases are more challenging for both algorithms, although GARRLiC manages to provide more detailed microphysical retrievals compared to AERONET, while LIRIC effectively discriminates dust and marine particles in its concentration profile retrievals. The results are also compared with modelled dust and marine concentration profiles and surface in situ measurements.

scholarly journals GARRLiC and LIRIC: strengths and limitations for the characterization of dust and marine particles along with their mixtures

2017 ◽  
Author(s):  
Alexandra Tsekeri ◽  
Anton Lopatin ◽  
Vassilis Amiridis ◽  
Eleni Marinou ◽  
Julia Igloffstein ◽  
...  
Keyword(s):  
Eastern Mediterranean ◽  
Saharan Dust ◽  
Mixing Conditions ◽  
Microphysical Properties ◽  
First Case ◽  
Marine Particles ◽  
Ground Based Lidar ◽  
Photometric Measurements ◽  
Combined Data

Abstract. The Generalized Aerosol Retrieval from Radiometer and Lidar Combined data algorithm (GARRLiC) and the LIdar-Radiometer Inversion Code (LIRIC) provide the opportunity to study the aerosol vertical distribution by combining ground-based lidar and sun-photometric measurements. Here, we utilize the capabilities of both algorithms for the characterization of Saharan dust and marine particles, along with their mixtures, in the South-Eastern Mediterranean during the CHARacterization of Aerosol mixtures of Dust and Marine origin Experiment (CHARADMExp). Three case studies are presented, focusing on dust-dominated, marine-dominated and dust/marine mixing conditions. GARRLiC and LIRIC achieve a satisfactory characterization for the first case in terms of particle microphysical properties and concentration profiles. Τhe marine-dominated and the mixture cases are more challenging for both algorithms, although GARRLiC manages to provide more detailed microphysical retrievals compared to AERONET, while LIRIC effectively discriminates dust and marine in its concentration profile retrievals.

scholarly journals Multi-Sensor Observation of a Saharan Dust Outbreak over Transylvania, Romania in April 2019

Atmosphere ◽  
2020 ◽  
Vol 11 (4) ◽  
pp. 364 ◽  
Author(s):  
Nicolae Ajtai ◽  
Horațiu Ștefănie ◽  
Alexandru Mereuță ◽  
Andrei Radovici ◽  
Camelia Botezan
Keyword(s):  
Complex Analysis ◽  
Remote Sensing Data ◽  
Ground Level ◽  
Global Scale ◽  
Saharan Dust ◽  
Back Trajectories ◽  
Microphysical Properties ◽  
Multi Wavelength ◽  
Degree Of Certainty

Mineral aerosols are considered to be the second largest source of natural aerosol, the Saharan desert being the main source of dust at global scale. Under certain meteorological conditions, Saharan dust can be transported over large parts of Europe, including Romania. The aim of this paper is to provide a complex analysis of a Saharan dust outbreak over the Transylvania region of Romania, based on the synergy of multiple ground-based and satellite sensors in order to detect the dust intrusion with a higher degree of certainty. The measurements were performed during the peak of the outbreak on April the 24th 2019, with instruments such as a Cimel sun-photometer and a multi-wavelength Raman depolarization lidar, together with an in-situ particle counter measuring at ground level. Remote sensing data from MODIS sensors on Terra and Aqua were also analyzed. Results show the presence of dust aerosol layers identified by the multi-wavelength Raman and depolarization lidar at altitudes of 2500–4000 m, and 7000 m, respectively. The measured optical and microphysical properties, together with the HYSPLIT back-trajectories, NMMB/BSC dust model, and synoptic analysis, confirm the presence of lofted Saharan dust layers over Cluj-Napoca, Romania. The NMMB/BSC dust model predicted dust load values between 1 and 1.5 g/m2 over Cluj-Napoca at 12:00 UTC for April the 24th 2019. Collocated in-situ PM monitoring showed that dry deposition was low, with PM10 and PM2.5 concentrations similar to the seasonal averages for Cluj-Napoca.

scholarly journals In Situ Samplings and Remote Sensing Measurements to Characterize Aerosol Properties over Southeast Italy

2008 ◽  
Vol 25 (8) ◽  
pp. 1341-1356 ◽  
Author(s):  
V. Bellantone ◽  
I. Carofalo ◽  
F. De Tomasi ◽  
M. R. Perrone ◽  
M. Santese ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Eastern Mediterranean ◽  
Aluminum Silicate ◽  
Volume Distribution ◽  
Vertical Profiles ◽  
Backscatter Coefficient ◽  
Particle Volume ◽  
Microphysical Properties ◽  
Fine Mode

Abstract Ground-based particulate matter (PM) samplers, an XeF Raman lidar operating in the framework of the European Aerosol Research Lidar Network (EARLINET), and a sun/sky radiometer operating in the framework of the Aerosol Robotic Network (AERONET) have been used to characterize vertical profiles, optical and microphysical properties, and chemical composition of aerosols during the 29 June–1 July 2005 dust outbreak that occurred over the central-eastern Mediterranean. Aerosol backscatter coefficient, total depolarization, and lidar ratio vertical profiles revealed that a well-mixed dust layer extending from ∼0.5 to 6 km was present over southeastern Italy on 30 June. Sun/sky radiometer measurements revealed a bimodal lognormal size distribution during all measurement days. The particle volume distribution was found to be well correlated either to the PM mass distribution measured at ground by a seven-stage cascade impactor and to the fine to total suspended PM mass ratio measured by ground-based PM samplers. Scanning electron microscopy and ion chromatography analyses on PM samples revealed that coarse-mode aerosols were mainly made of carbonate, aluminum-silicate, and sea salt particles. Carbon, sulfate, and nitrate particles were the main components of fine-mode aerosols representing more than 50% of the total aerosol load; the significant role of fine-mode anthropogenic particles during a dust event is highlighted. Finally, the potential capabilities of complementary measurements by passive and active remote sensing techniques and in situ observations to retrieve the vertical distribution of the particle number and mass concentration are analyzed and discussed.

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

2015 ◽  
Vol 8 (9) ◽  
pp. 9289-9338 ◽  
Author(s):  
M. J. Granados-Muñoz ◽  
J. A. Bravo-Aranda ◽  
D. Baumgardner ◽  
J. L. Guerrero-Rascado ◽  
D. Pérez-Ramírez ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Volume Concentration ◽  
Mineral Dust ◽  
In Situ Measurements ◽  
Saharan Dust ◽  
Night Time ◽  
Passive Remote Sensing ◽  
Microphysical Properties ◽  
Multi Wavelength

Abstract. In this work we present an analysis of mineral dust optical and microphysical properties obtained from different retrieval techniques applied to active and passive remote sensing measurements, including a comparison with simultaneous in-situ aircraft measurements. Data were collected in a field campaign performed during a mineral dust outbreak a Granada, Spain, experimental site (37.16° N, 3.61° W, 680 m a.s.l.) on the 27 June 2011. Column-integrated properties are provided by sun- and star-photometry which allows a continuous evaluation of the mineral dust optical properties during both day and night-time. 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 night-time. LIRIC retrievals reveal several 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 both volume concentration and dust particle polarization ratios measured with in-situ and remote sensing techniques. Results for the depolarization measurements in the dust layer indicate reasonable agreement within the estimated uncertainties. The differences in the volume concentration profiles, although somewhat larger, are still within the expected uncertainties.

The potential of a synergestic lidar and sunphotometer retrieval for the characterization of a dust event over Finokalia and for aerosol model evaluation

2020 ◽  
Author(s):  
Dimitra Konsta ◽  
Alexandra Tsekeri ◽  
Stavros Solomos ◽  
Anton Lopatin ◽  
Philippe Goloub ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Saharan Dust ◽  
Research Network ◽  
Dust Event ◽  
Aerosol Model ◽  
Microphysical Properties ◽  
Low Levels ◽  
Dust Effects ◽  
Good Agreement

<p>The ability of three-dimensional dust models to accurately represent the dust life cycle is crucial for describing dust effects on radiation and clouds and for reducing the uncertainties on these processes. To improve the reliabilty of dust models, it is therefore imperative to carry out thorough evaluations of the dust properties. Dust optical and microphysical properties are accurately accessed through groundbased observations: multiwavelength lidars and sunphotometers. In this study we use the Generalized Retrieval of Atmospheric and Surface Properties (GRASP) data algorithm that combines the lidar and sunphotometer data to retrieve dust properties. GRASP is applied on a Saharan dust episode over Finokalia, Crete in Greece, on 14 May 2017. More precisely the measurements from PollyXT lidar participating in the European Aerosol Research Network (EARLINET) and the CIMEL sunphotometer participating in Aerosol Robotic Network (AERONET) are synergetically combined using the GRASP algorithm. The dust event is fully characterised through the retrieval of dust optical and microphysical properties. The retrieved properties are found to be in good agreement with the initial measurements from the AERONET sunphotometer and the lidar. Then the aforementioned tools are used to evaluate the performance of the regional dust model NMME-DREAM that has been developed to simulate and predict the atmospheric cycle of mineral dust aerosols. It is shown that the model has problems in simulating the high dust concentration values at low levels, probably due to the low spatial resolution of the model that causes difficulties in capturing the orography and the downdrafts winds.</p>

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 Particle settling and vertical mixing in the Saharan Air Layer as seen from an integrated model, lidar, and in situ perspective

2017 ◽  
Vol 17 (1) ◽  
pp. 297-311 ◽  
Author(s):  
Josef Gasteiger ◽  
Silke Groß ◽  
Daniel Sauer ◽  
Moritz Haarig ◽  
Albert Ansmann ◽  
...  
Keyword(s):  
Vertical Mixing ◽  
Saharan Dust ◽  
Dust Particles ◽  
Particle Settling ◽  
Western Atlantic ◽  
Particle Counter ◽  
Saharan Air Layer ◽  
Lidar Measurements ◽  
Ground Based Lidar

Abstract. Long-range transport of aerosol in the Saharan Air Layer (SAL) across the Atlantic plays an important role for weather, climate, and ocean fertilization. However, processes occurring within the SAL and their effects on aerosol properties are still unclear. In this work we study particle settling and vertical mixing within the SAL based on measured and modeled vertical aerosol profiles in the upper 1 km of the transported SAL. We use ground-based lidar measurements and airborne particle counter measurements over the western Atlantic, collected during the SALTRACE campaign, as well as space-based CALIOP lidar measurements from Africa to the western Atlantic in the summer season. In our model we take account of the optical properties and the Stokes gravitational settling of irregularly shaped Saharan dust particles.We test two hypotheses about the occurrence of vertical mixing within the SAL over the Atlantic to explain the aerosol profiles observed by the lidars and the particle counter. Our first hypothesis (H1) assumes that no mixing occurs in the SAL leading to a settling-induced separation of particle sizes. The second hypothesis (H2) assumes that vertical mixing occurs in the SAL allowing large super-micron dust particles to stay airborne longer than without mixing. The uncertainties of the particle linear depolarization ratio (δl) profiles measured by the ground-based lidars are comparable to the modeled differences between H1 and H2 and do not allow us to conclude which hypothesis fits better. The SALTRACE in situ data on size-resolved particle number concentrations show a presence of large particles near the SAL top that is inconsistent with H1. The analysis of the CALIOP measurements also reveals that the average δl profile over the western Atlantic is inconsistent with H1. Furthermore, it was found that the average δl profile in the upper 1 km of the SAL does not change along its transport path over the Atlantic. These findings give evidence that vertical mixing within the SAL is a common phenomenon with significant consequences for the evolution of the size distribution of super-micron dust particles during transport over the Atlantic. Further research is needed to precisely characterize the processes that are relevant for this phenomenon.

The Use of Advanced Analytical Techniques for Characterization of the Chemical, Physical, and Crystallographic Nature of a Surface

1973 ◽  
Vol 31 ◽  
pp. 132-133 ◽  
Author(s):  
R. E. Herfert
Keyword(s):  
Surface Characterization ◽  
Analytical Techniques ◽  
X Ray Diffraction ◽  
Depth Of Penetration ◽  
X Ray ◽  
The Past ◽  
Transmission Electron ◽  
Scanning Electron

Studies of the nature of a surface, either metallic or nonmetallic, in the past, have been limited to the instrumentation available for these measurements. In the past, optical microscopy, replica transmission electron microscopy, electron or X-ray diffraction and optical or X-ray spectroscopy have provided the means of surface characterization. Actually, some of these techniques are not purely surface; the depth of penetration may be a few thousands of an inch. Within the last five years, instrumentation has been made available which now makes it practical for use to study the outer few 100A of layers and characterize it completely from a chemical, physical, and crystallographic standpoint. The scanning electron microscope (SEM) provides a means of viewing the surface of a material in situ to magnifications as high as 250,000X.

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