Raman lidar observations of a Saharan dust outbreak event: Characterization of the dust optical properties and determination of particle size and microphysical parameters

2012 ◽  
Vol 50 ◽  
pp. 66-78 ◽  
Author(s):  
Paolo Di Girolamo ◽  
Donato Summa ◽  
Rohini Bhawar ◽  
Tatiana Di Iorio ◽  
Marco Cacciani ◽  
...  
Keyword(s):  
Particle Size ◽  
Optical Properties ◽  
Saharan Dust ◽  
Raman Lidar ◽  
Microphysical Parameters ◽  
Lidar Observations

scholarly journals Properties of arctic haze aerosol from lidar observations during iarea 2015 campaign on spitsbergen

2018 ◽  
Vol 176 ◽  
pp. 05024 ◽  
Author(s):  
Iwona S. Stachlewska ◽  
Christoph Ritter ◽  
Christine Böckmann ◽  
Ronny Engelmann
Keyword(s):  
Optical Properties ◽  
Black Carbon ◽  
Biomass Burning ◽  
The Arctic ◽  
Raman Lidar ◽  
Aerosol Composition ◽  
Microphysical Parameters ◽  
Arctic Haze ◽  
Parameters Inversion ◽  
Lidar Observations

Arctic Haze event was observed on 5-8 April 2015 using simultaneously Near-range Aerosol Raman Lidar of IGFUW and Koldewey Aerosol Raman Lidar of AWI, both based at AWIPEV German-French station in Ny-Ålesund, Spitsbergen. The alterations in particle abundance and altitude of the aerosol load observed on following days of the event is analyzed. The daytime profiles of particle optical properties were obtained for both lidars, and then served as input for microphysical parameters inversion. The results indicate aerosol composition typical for the Arctic Haze. However, in some layers, a likely abundance of aqueous aerosol or black carbon originating in biomass burning over Siberia, changes measurably the Arctic Haze properties.

scholarly journals Observations of Saharan dust microphysical and optical properties from the Eastern Atlantic during NAMMA airborne field campaign

2011 ◽  
Vol 11 (2) ◽  
pp. 723-740 ◽  
Author(s):  
G. Chen ◽  
L. D. Ziemba ◽  
D. A. Chu ◽  
K. L. Thornhill ◽  
G. L. Schuster ◽  
...  
Keyword(s):  
Particle Size ◽  
Optical Properties ◽  
Dust Particle ◽  
Saharan Dust ◽  
Dust Particles ◽  
Small Range ◽  
Size Distributions ◽  
Particle Size Distributions ◽  
Field Campaign ◽  
Sahara Dust

Abstract. As part of the international project entitled "African Monsoon Multidisciplinary Analysis (AMMA)", NAMMA (NASA AMMA) aimed to gain a better understanding of the relationship between the African Easterly Waves (AEWs), the Sahara Air Layer (SAL), and tropical cyclogenesis. The NAMMA airborne field campaign was based out of the Cape Verde Islands during the peak of the hurricane season, i.e., August and September 2006. Multiple Sahara dust layers were sampled during 62 encounters in the eastern portion of the hurricane main development region, covering both the eastern North Atlantic Ocean and the western Saharan desert (i.e., 5–22° N and 10–35° W). The centers of these layers were located at altitudes between 1.5 and 3.3 km and the layer thickness ranged from 0.5 to 3 km. Detailed dust microphysical and optical properties were characterized using a suite of in-situ instruments aboard the NASA DC-8 that included a particle counter, an Ultra-High Sensitivity Aerosol Spectrometer, an Aerodynamic Particle Sizer, a nephelometer, and a Particle Soot Absorption Photometer. The NAAMA sampling inlet has a size cut (i.e., 50% transmission efficiency size) of approximately 4 μm in diameter for dust particles, which limits the representativeness of the NAMMA observational findings. The NAMMA dust observations showed relatively low particle number densities, ranging from 268 to 461 cm−3, but highly elevated volume density with an average at 45 μm3 cm−3. NAMMA dust particle size distributions can be well represented by tri-modal lognormal regressions. The estimated volume median diameter (VMD) is averaged at 2.1 μm with a small range of variation regardless of the vertical and geographical sampling locations. The Ångström Exponent assessments exhibited strong wavelength dependence for absorption but a weak one for scattering. The single scattering albedo was estimated at 0.97 ± 0.02. The imaginary part of the refractive index for Sahara dust was estimated at 0.0022, with a range from 0.0015 to 0.0044. Closure analysis showed that observed scattering coefficients are highly correlated with those calculated from spherical Mie-Theory and observed dust particle size distributions. These values are generally consistent with literature values reported from studies with similar particle sampling size range.

scholarly journals Lidar Overlap Function Determination Using the Raman Lidar Signals

2020 ◽  
Vol 237 ◽  
pp. 07018
Author(s):  
Jaswant ◽  
Shishir Kumar Singh ◽  
Radhakrishnan S.R. ◽  
Devesh Shukla ◽  
Chhemendra Sharma
Keyword(s):  
Optical Properties ◽  
Simple Technique ◽  
Near Field ◽  
Lower Atmosphere ◽  
Raman Lidar ◽  
Lidar System ◽  
Field Range ◽  
The Mean ◽  
Overlap Factor

The determination of vertical distribution of optical properties of clouds and aerosols using the lidar system is affected by the incomplete overlap between the field of view of transmitter i.e. laser beam & the receiver in the near‐field range. Thus, the study of vertical profiles of aerosol optical properties in the lower atmosphere is erroneous without the correction of lidar overlap function. Here we have analysed the effect of overlap using a simple technique proposed by Ansmann and Wandinger to determine overlap function. We have determined the overlap factor for 5 different days of June 2016 and then calculated the mean overlap profile and determined the relative deviation of each day with respect to mean overlap factor. Results reveal that the complete overlap was achieved beyond 300 meters.

Advances in the growth and characterization of Ge quantum dots and islands

2005 ◽  
Vol 20 (12) ◽  
pp. 3278-3293 ◽  
Author(s):  
J-M. Baribeau ◽  
N.L. Rowell ◽  
D.J. Lockwood
Keyword(s):  
Quantum Dots ◽  
Optical Properties ◽  
Spatial Distribution ◽  
Strain Distribution ◽  
Growth Parameters ◽  
Nucleation And Growth ◽  
Structural And Optical Properties ◽  
Ge Quantum Dots

We review recent advances in the growth of Si1−xGex islands and Ge dots on (001) Si. We first discuss the evolution of the island morphology with Si1−xGex coverage and the effect of growth parameters or post-growth annealing on the shape of the islands and dots. We outline some of the structural and optical properties of Si1−xGex islands and assess progress in the determination of their composition and strain distribution. Finally, we discuss various approaches currently being investigated to engineer Si1−xGex quantum dots and in particular to control their size, density, and spatial distribution. For example, we show how C pre-deposition on Si (001) can influence the nucleation and growth of Ge islands.

scholarly journals Observations of Saharan dust microphysical and optical properties from the Eastern Atlantic during NAMMA airborne field campaign

2010 ◽  
Vol 10 (5) ◽  
pp. 13445-13493 ◽  
Author(s):  
G. Chen ◽  
L. D. Ziemba ◽  
D. A. Chu ◽  
K. L. Thornhill ◽  
G. L. Schuster ◽  
...  
Keyword(s):  
Particle Size ◽  
Optical Properties ◽  
Dust Particle ◽  
North Atlantic Ocean ◽  
Saharan Dust ◽  
Small Range ◽  
Size Distributions ◽  
Particle Size Distributions ◽  
Field Campaign ◽  
Sahara Dust

Abstract. As part of the international project entitled "African Monsoon Multidisciplinary Analysis (AMMA)", NAMMA (NASA AMMA) aimed to gain a better understanding of the relationship between the African Easterly Waves (AEWs), the Sahara Air Layer (SAL), and tropical cyclogenesis. The NAMMA airborne field campaign was based out of the Cape Verde Islands during the peak of the hurricane season, i.e., August and September 2006. Multiple Sahara dust layers were sampled during 62 encounters in the eastern portion of the hurricane main development region, covering both the eastern North Atlantic Ocean and the western Saharan desert (i.e., 5–22° N and 10–35° W). The centers of these layers were located at altitudes between 1.5 and 3.3 km and the layer thickness ranged from 0.5 to 3 km. Detailed dust microphysical and optical properties were characterized using a suite of in situ instruments aboard the NASA DC-8 that included a particle counter, an Ultra-High Sensitivity Aerosol Spectrometer, an Aerodynamic Particle Sizer, nephelometer, and Particle Soot Absorption Photometer. The NAMMA dust observations showed relatively low particle number densities, ranging from 268 to 461 cm−3, but highly elevated volume density with an average at 45 μm3 cm−3. NAMMA dust particle size distributions were well represented by tri-modal lognormal regressions. The estimated volume median diameter (VMD) is averaged at 2.1 μm with a small range of variation regardless of the vertical and geographical sampling locations. The absorption coefficient measurements exhibited a strong wavelength dependence for absorption but a weak one for scattering. The single scattering albedo was estimated at 0.97±0.02. Closure analyses showed that observed scattering and absorption coefficients are highly correlated with those calculated from spherical Mie-Theory and observed dust particle size distributions. The imaginary part of the refractive index for Sahara dust was estimated at 0.0022, with a range from 0.0015 to 0.0044. These values are generally consistent with literature values.

Preparation and Characterization of Broad-Spectrum Sunscreens Loaded Nanostructured Lipid Carrier

2013 ◽  
Vol 669 ◽  
pp. 67-71
Author(s):  
Yan Ling Chen ◽  
Qiang Xia
Keyword(s):  
Particle Size ◽  
Physical State ◽  
Retention Rate ◽  
Nanostructured Lipid Carrier ◽  
High Pressure Homogenization ◽  
Spectrophotometric Detection ◽  
Ultraviolet Absorbance ◽  
Organic Uv Filters

A comprehensive photoprotective formulation was developed to enhance photoprotection ,compared to a conventional nanoemulsion ,having the concentration of two new molecular sunscreens, namely Diethylamino hydyoxybenzoyl hexyl benzoate(Uvinul ® A Plus) and Ethylhexyl triazone(Uvinul® T 150). In the present paper, the sunscreen mixture was incorporated into nanostructured lipid carriers (NLCs). After the production by hot high pressure homogenization, the NLC were analyzed in terms of particle size, physical state, particle shape, ultraviolet absorbance and stability. The particle size for all NLC was around 100-900 nm after production. The determination of 2 organic UV filters was performed by HPLC with UV spectrophotometric detection. The loading capacities for molecular sunscreens was up to 30%. In the sunlight, the retention rate of Uvinul ® A Plus and Uvinul ® T150 was still up to 80% after three months .

Characterization of solid magnetic nanoparticles by means of solid sampling high resolution continuum source electrothermal atomic absorption spectrometry

2016 ◽  
Vol 31 (12) ◽  
pp. 2391-2398 ◽  
Author(s):  
E. Vereda Alonso ◽  
M. M. López Guerrero ◽  
M. T. Siles Cordero ◽  
J. M. Cano Pavón ◽  
A. García de Torres
Keyword(s):  
Particle Size ◽  
Magnetic Nanoparticles ◽  
Iron Concentration ◽  
Electrothermal Atomic Absorption Spectrometry ◽  
Direct Determination ◽  
Absorption Spectrometry ◽  
Solid Sampling ◽  
Continuum Source

Direct determination of iron concentration and particle size of solid MNPs using HR CS GFAAS.

scholarly journals Profiling of Saharan dust from the Caribbean to western Africa – Part 1: Layering structures and optical properties from shipborne polarization/Raman lidar observations

2017 ◽  
Vol 17 (21) ◽  
pp. 12963-12983 ◽  
Author(s):  
Franziska Rittmeister ◽  
Albert Ansmann ◽  
Ronny Engelmann ◽  
Annett Skupin ◽  
Holger Baars ◽  
...  
Keyword(s):  
Optical Properties ◽  
Conceptual Model ◽  
Long Range Transport ◽  
Tropical Atlantic ◽  
Raman Lidar ◽  
Western Africa ◽  
Range Transport ◽  
Lidar Ratio ◽  
The Caribbean ◽  
Lidar Observations

Abstract. We present final and quality-assured results of multiwavelength polarization/Raman lidar observations of the Saharan air layer (SAL) over the tropical Atlantic. Observations were performed aboard the German research vessel R/V Meteor during the 1-month transatlantic cruise from Guadeloupe to Cabo Verde over 4500 km from 61.5 to 20° W at 14–15° N in April–May 2013. First results of the shipborne lidar measurements, conducted in the framework of SALTRACE (Saharan Aerosol Long-range Transport and Aerosol–Cloud Interaction Experiment), were reported by Kanitz et al.(2014). Here, we present four observational cases representing key stages of the SAL evolution between Africa and the Caribbean in detail in terms of layering structures and optical properties of the mixture of predominantly dust and aged smoke in the SAL. We discuss to what extent the lidar results confirm the validity of the SAL conceptual model which describes the dust long-range transport and removal processes over the tropical Atlantic. Our observations of a clean marine aerosol layer (MAL, layer from the surface to the SAL base) confirm the conceptual model and suggest that the removal of dust from the MAL, below the SAL, is very efficient. However, the removal of dust from the SAL assumed in the conceptual model to be caused by gravitational settling in combination with large-scale subsidence is weaker than expected. To explain the observed homogenous (height-independent) dust optical properties from the SAL base to the SAL top, from the African coast to the Caribbean, we have to assume that the particle sedimentation strength is reduced and dust vertical mixing and upward transport mechanisms must be active in the SAL. Based on lidar observations on 20 nights at different longitudes in May 2013, we found, on average, MAL and SAL layer mean values (at 532 nm) of the extinction-to-backscatter ratio (lidar ratio) of 17±5 sr (MAL) and 43±8 sr (SAL), of the particle linear depolarization ratio of 0.025±0.015 (MAL) and 0.19±0.09 (SAL), and of the particle extinction coefficient of 67±45 Mm−1 (MAL) and 68±37 Mm−1 (SAL). The 532 nm optical depth of the lofted SAL was found to be, on average, 0.15±0.13 during the ship cruise. The comparably low values of the SAL mean lidar ratio and depolarization ratio (compared to typical pure dust values of 50–60 sr and 0.3, respectively) in combination with backward trajectories indicate a smoke contribution to light extinction of the order of 20 % during May 2013, at the end of the burning season in central-western Africa.

Determination of the wavelength dependence of refractive indices of flame soot

1990 ◽  
Vol 430 (1880) ◽  
pp. 577-591 ◽  
Keyword(s):  
Particle Size ◽  
Optical Properties ◽  
Light Scattering ◽  
Equivalence Ratio ◽  
Wavelength Dependence ◽  
Refractive Indices ◽  
Spectral Variation ◽  
Scattering Measurements ◽  
Oxygen Flame

The spectral variation of the optical properties of soot particles is determined by combining classical and dynamic light scattering measurements with the Kramers-Krönig relations. Particle size and number densities are determined from scattering/extinction and autocorrelation measurements at the wavelength of 0.488 μm. This information is then combined with the spectral extinction measurements in the wavelength range 0.2 to 6.4 μm to determine the spectral variation of the refractive indices of flame soot. Results are presented for a premixed propane-oxygen flame with a fuel equivalence ratio ϕ = 1.8. The sensitivity of the technique and its advantage over the previous methods are discussed.

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