scholarly journals Retrieving simulated volcanic, desert dust and sea-salt particle properties from two/three-component particle mixtures using UV-VIS polarization lidar and T matrix

2013 ◽  
Vol 13 (14) ◽  
pp. 6757-6776 ◽  
Author(s):  
G. David ◽  
B. Thomas ◽  
T. Nousiainen ◽  
A. Miffre ◽  
P. Rairoux
Keyword(s):  
Volcanic Ash ◽  
Sea Salt ◽  
Water Soluble ◽  
Nonspherical Particles ◽  
Depolarization Ratio ◽  
Component Mixture ◽  
Desert Dust ◽  
Two Component ◽  
T Matrix ◽  
Component Particle

Abstract. During transport by advection, atmospheric nonspherical particles, such as volcanic ash, desert dust or sea-salt particles experience several chemical and physical processes, leading to a complex vertical atmospheric layering at remote sites where intrusion episodes occur. In this paper, a new methodology is proposed to analyse this complex vertical layering in the case of a two/three-component particle external mixtures. This methodology relies on an analysis of the spectral and polarization properties of the light backscattered by atmospheric particles. It is based on combining a sensitive and accurate UV-VIS polarization lidar experiment with T-matrix numerical simulations and air mass back trajectories. The Lyon UV-VIS polarization lidar is used to efficiently partition the particle mixture into its nonspherical components, while the T-matrix method is used for simulating the backscattering and depolarization properties of nonspherical volcanic ash, desert dust and sea-salt particles. It is shown that the particle mixtures' depolarization ratio δ p differs from the nonspherical particles' depolarization ratio δns due to the presence of spherical particles in the mixture. Hence, after identifying a tracer for nonspherical particles, particle backscattering coefficients specific to each nonspherical component can be retrieved in a two-component external mixture. For three-component mixtures, the spectral properties of light must in addition be exploited by using a dual-wavelength polarization lidar. Hence, for the first time, in a three-component external mixture, the nonsphericity of each particle is taken into account in a so-called 2β + 2δ formalism. Applications of this new methodology are then demonstrated in two case studies carried out in Lyon, France, related to the mixing of Eyjafjallajökull volcanic ash with sulfate particles (case of a two-component mixture) and to the mixing of dust with sea-salt and water-soluble particles (case of a three-component mixture). This new methodology, which is able to provide separate vertical profiles of backscattering coefficient for mixed atmospheric dust, sea-salt and water-soluble particles, may be useful for accurate radiative forcing assessments.

scholarly journals Retrieving volcanic, desert dust, and sea-salt particle properties from two/three-component particle mixtures after long-range transport using UV-VIS polarization Lidar and T-matrix

2013 ◽  
Vol 13 (1) ◽  
pp. 1891-1947 ◽  
Author(s):  
G. David ◽  
B. Thomas ◽  
T. Nousiainen ◽  
A. Miffre ◽  
P. Rairoux
Keyword(s):  
Long Range ◽  
Sea Salt ◽  
Water Soluble ◽  
Long Range Transport ◽  
Nonspherical Particles ◽  
Component Mixture ◽  
Desert Dust ◽  
Range Transport ◽  
T Matrix ◽  
Volcanic Desert

Abstract. During transport by advection, atmospheric nonspherical particles, such as volcanic, desert dust or sea-salt particles experience several chemical and physical processes, leading to a complex vertical atmospheric layering at remote sites where intrusion episodes occur. In this contribution, a new methodology is proposed to analyze this complex vertical layering in the case of a two/three-component particle external mixtures after long-range transport. This methodology relies on a precise analysis of the spectral and polarization properties of the light backscattered by atmospheric particles. It is based on combining a sensitive and accurate UV-VIS polarization Lidar experiment with accurate T-matrix numerical simulations and air mass back-trajectories. The Lyon UV-VIS polarization Lidar is used to efficiently partition the particle mixture into its nonspherical components, while the T-matrix algorithm is used for computing backscattering and depolarization properties specific to nonspherical volcanic, desert dust and sea-salt particles, the latter being described in the cubic shape approximation. It is shown that, after long-range transport, the particle mixtures' depolarization ratio δp differs from the nonspherical particles' depolarization ratio δns due to the presence of spherical particles in the mixture. Hence, after identifying a tracer for nonspherical particles, particle backscattering coefficients specific to each nonspherical component can be retrieved in a two component external mixture. For three-component mixtures, the spectral properties of light must in addition be addressed by using a dual-wavelength polarization Lidar. Hence, for the first time, in a three-component external mixture, the nonsphericity of each particle is taken into account in a so-called 2β + 2δ formalism. Applications of this new methodology are then demonstrated in two case studies carried out in Lyon, France, related to the mixing of Eyjafjallajökull volcanic ash with sulphate particles (case of a two-component mixture) and to the mixing of dust with sea-salt and water-soluble particles (case of a three-component mixture). This new methodology, which is able to provide separate vertical profiles of mixed atmospheric dust, sea-salt and water-soluble particles, may be useful for accurate radiative forcing assessments.

Fifth virial coefficient of a two-component mixture of hard discs

1997 ◽  
Vol 90 (4) ◽  
pp. 679-681
Author(s):  
F. SAIJA ◽  
G. FIUMARA ◽  
P.V. GIAQUINTA
Keyword(s):  
Virial Coefficient ◽  
Component Mixture ◽  
Two Component

scholarly journals Two-Component Mixture Model in the Presence of Covariates

2021 ◽  
pp. 1-15 ◽  
Author(s):  
Nabarun Deb ◽  
Sujayam Saha ◽  
Adityanand Guntuboyina ◽  
Bodhisattva Sen
Keyword(s):  
Mixture Model ◽  
Component Mixture ◽  
Two Component

scholarly journals Primary aerosol and secondary inorganic aerosol budget over the Mediterranean Basin during 2012 and 2013

2018 ◽  
Vol 18 (7) ◽  
pp. 4911-4934 ◽  
Author(s):  
Jonathan Guth ◽  
Virginie Marécal ◽  
Béatrice Josse ◽  
Joaquim Arteta ◽  
Paul Hamer
Keyword(s):  
Mediterranean Basin ◽  
Transport Model ◽  
Coastal Areas ◽  
Sea Salt ◽  
Anthropogenic Emissions ◽  
Carbonaceous Aerosols ◽  
Desert Dust ◽  
Inorganic Aerosols ◽  
The Mediterranean ◽  
The Mediterranean Basin

Abstract. In the frame of the Chemistry-Aerosol Mediterranean Experiment (ChArMEx), we analyse the budget of primary aerosols and secondary inorganic aerosols over the Mediterranean Basin during the years 2012 and 2013. To do this, we use two year-long numerical simulations with the chemistry-transport model MOCAGE validated against satellite- and ground-based measurements. The budget is presented on an annual and a monthly basis on a domain covering 29 to 47° N latitude and 10° W to 38° E longitude. The years 2012 and 2013 show similar seasonal variations. The desert dust is the main contributor to the annual aerosol burden in the Mediterranean region with a peak in spring, and sea salt being the second most important contributor. The secondary inorganic aerosols, taken as a whole, contribute a similar level to sea salt. The results show that all of the considered aerosol types, except for sea salt aerosols, experience net export out of our Mediterranean Basin model domain, and thus this area should be considered as a source region for aerosols globally. Our study showed that 11 % of the desert dust, 22.8 to 39.5 % of the carbonaceous aerosols, 35 % of the sulfate and 9 % of the ammonium emitted or produced into the study domain are exported. The main sources of variability for aerosols between 2012 and 2013 are weather-related variations, acting on emissions processes, and the episodic import of aerosols from North American fires. In order to assess the importance of the anthropogenic emissions of the marine and the coastal areas which are central for the economy of the Mediterranean Basin, we made a sensitivity test simulation. This simulation is similar to the reference simulation but with the removal of the international shipping emissions and the anthropogenic emissions over a 50 km wide band inland along the coast. We showed that around 30 % of the emissions of carbonaceous aerosols and 35 to 60 % of the exported carbonaceous aerosols originates from the marine and coastal areas. The formation of 23, 27 and 27 %, respectively of, ammonium, nitrate and sulfate aerosols is due to the emissions within the marine and coastal area.

scholarly journals Benefit of depolarization ratio at λ = 1064 nm for the retrieval of the aerosol microphysics from lidar measurements

2014 ◽  
Vol 7 (11) ◽  
pp. 3773-3781 ◽  
Author(s):  
J. Gasteiger ◽  
V. Freudenthaler
Keyword(s):  
Optical Properties ◽  
Mass Concentration ◽  
Volcanic Ash ◽  
Single Scattering ◽  
Depolarization Ratio ◽  
Complex Relation ◽  
Microphysical Properties ◽  
Lidar Measurements ◽  
Increased Sensitivity ◽  
Linear Depolarization Ratio

Abstract. A better quantification of aerosol properties is required for improving the modelling of aerosol effects on weather and climate. This task is methodologically demanding due to the diversity of the microphysical properties of aerosols and the complex relation between their microphysical and optical properties. Advanced lidar systems provide spatially and temporally resolved information on the aerosol optical properties that is sufficient for the retrieval of important aerosol microphysical properties. Recently, the mass concentration of transported volcanic ash, which is relevant for the flight safety of aeroplanes, was retrieved from measurements of such lidar systems in southern Germany. The relative uncertainty of the retrieved mass concentration was on the order of ±50%. The present study investigates improvements of the retrieval accuracy when the capability of measuring the linear depolarization ratio at 1064 nm is added to the lidar setup. The lidar setups under investigation are based on those of MULIS and POLIS of the Ludwig-Maximilians-Universität in Munich (Germany) which measure the linear depolarization ratio at 355 and 532 nm with high accuracy. The improvements are determined by comparing uncertainties from retrievals applied to simulated measurements of this lidar setup with uncertainties obtained when the depolarization at 1064 nm is added to this setup. The simulated measurements are based on real lidar measurements of transported Eyjafjallajökull volcano ash. It is found that additional 1064 nm depolarization measurements significantly reduce the uncertainty of the retrieved mass concentration and effective particle size. This significant improvement in accuracy is the result of the increased sensitivity of the lidar setup to larger particles. The size dependence of the depolarization does not vary strongly with refractive index, thus we expect similar benefits for the retrieval in case of measurements of other volcanic ash compositions and also for transported desert dust. For the retrieval of the single scattering albedo, which is relevant to the radiative transfer in aerosol layers, no significant improvements were found.

scholarly journals Remote sensing of aerosols by synergy of caliop and modis

2018 ◽  
Vol 176 ◽  
pp. 08012
Author(s):  
Rei Kudo ◽  
Tomoaki Nishizawa ◽  
Akiko Higurashi ◽  
Eiji Oikawa
Keyword(s):  
Remote Sensing ◽  
Biomass Burning ◽  
Sea Salt ◽  
Water Soluble ◽  
Dust Particles ◽  
Vertical Profiles ◽  
Dust Event ◽  
Carbonaceous Particles ◽  
The Individual ◽  
Better Than

For the monitoring of the global 3-D distribution of aerosol components, we developed the method to retrieve the vertical profiles of water-soluble, light absorbing carbonaceous, dust, and sea salt particles by the synergy of CALIOP and MODIS data. The aerosol product from the synergistic method is expected to be better than the individual products of CALIOP and MODIS. We applied the method to the biomass-burning event in Africa and the dust event in West Asia. The reasonable results were obtained; the much amount of the water-soluble and light absorbing carbonaceous particles were estimated in the biomass-burning event, and the dust particles were estimated in the dust event.

scholarly journals Photoisomerization of 1-triphenylmethylcyclopentadiene. Di-π-methane rearrangement to 5,6,6-triphenylbicyclo[3.1.0]hex-2-ene

1977 ◽  
Vol 55 (1) ◽  
pp. 29-33 ◽  
Author(s):  
Stefan Weigl ◽  
John Warkentin
Keyword(s):  
Component Mixture ◽  
Two Component ◽  
Rearrangement Mechanism

Triphenylmethylcyclopentadiene exists as a mixture of isomers, the minor and major components of which are shown to be 1-triphenylmethylcyclopentadiene (1) and 2-triphenylmethyl-cyclopentadiene (2), respectively.Direct irradiation of a mixture of 1 and 2 led to formation of 5,6,6,-triphenylbicyclo[3.1.0]hex-2-ene (3) via rearrangement of 1. Acetophenone-sensitized irradiation of the same mixture gave 3 as well as a two component mixture of photodimers of 1 and/or 2. Results are interpreted in terms of the di-π-methane rearrangement mechanism.

Analysing sport data with clusters of opposite preferences

2018 ◽  
Vol 18 (5-6) ◽  
pp. 505-524 ◽  
Author(s):  
Rosaria Simone ◽  
Maria Iannario
Keyword(s):  
Sport Participation ◽  
Sport Activity ◽  
Discrete Models ◽  
Component Mixture ◽  
Rating Data ◽  
Self Evaluation ◽  
Specific Policy ◽  
Two Component ◽  
Competing Models ◽  
Selection Of

In the analysis of questionnaire-based evaluation of sport preferences, measurements of sport participation, opinions on social implications such as resurgence of racism, violence in stadiums and doping, the need arises to establish connections among motivations, subjects’ characteristics and responses. In this setting, the article deals with a selection of statistical models suitable to analyse sport rating data in which clusters of opposite responses are observed. Specifically, a two-component mixture of inverse hypergeometric (MIHG) distributions will be introduced and tested against competing models in order to yield a multifold interpretation of results. The ultimate comparative analysis will consider discrete models with a specific focus on those accounting for both uncertainty and feeling of self-evaluation in presence of inflation at the extreme categories. After a brief review of the methods, the proposal will be discussed both on ranking and rating data on the basis of two surveys on sport preferences and on measurements of sport activity: the identification of clusters of respondents with opposite choices will be investigated also in terms of covariates by comparing fitting performances of the selected models. The conclusions and insights offered by the study can be exploited to design plans of action for some specific policy or marketing strategy.

scholarly journals Near-Wake Observations behind Azimuthally Perforated Disks With Varying Hole Layout and Porosity in Smooth Airstreams at High Reynolds Numbers

2018 ◽  
Vol 141 (5) ◽  
Author(s):  
Raf Theunissen ◽  
Robert Worboys
Keyword(s):  
Drag Coefficient ◽  
Experimental Studies ◽  
Reynolds Numbers ◽  
Wake Flow ◽  
Mean Flow ◽  
Flow Topology ◽  
Near Wake ◽  
Two Component ◽  
High Reynolds ◽  
Component Particle

Porous disks are commonly encountered in experimental studies dealing with flow through objects such as wind turbines, parachutes, and fluidic devices to regulate pressure and/or downstream turbulence. Perforations are typically staggered and only porosity is altered to attain the required disk drag coefficient, despite a documented influence of topology. Few works have reported, however, to which extent the spatial distribution of the circular perforations affect the mean flow pertaining freestanding disks, and for this reason, this work presents a first, more systematic study focused on the effect of azimuthally varying hole topology and porosity on disk drag and near-wake characteristics. An experimental study performed in airflows of negligible freestream turbulence at Reynolds numbers in the order of 105 is reported and related to the existing literature to ensure reliability. Complementary to drag measurements, near-wake surveys have been performed on a variety of perforation layouts using two-component laser Doppler velocimetry and two-component particle image velocimetry. It is shown that minor changes in perforations can cause drastic changes in near-wake flow topology and no perforation layout can be consistently associated with highest drag. Explicit empirical expressions for drag coefficient linked with the simplified topologies considered have been derived.

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