Dust deposition

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Aeolian dust deposition rates in south-western Iran

Aeolian dust deposition rates in south-western Iran

The HYSPLIT model output further was run for ending point location in each of the three parts [a], [b], and [c] back to the 4 days trajectories that influenced the observed AOT spatial distribution and transport direction. The model output confirmed that, the dust belt stretches from the Sahara desert in Africa to the East Asia, conquered southwestern Iran which is being recognized as one of the global hotspots of aeolian dust through southwest of Iran including Kermanshah, Lorestan, and Khuzestan provinces. The results from this contribution were also capable of tracking dust events rather than monitoring the local and regional deposition rate. The measurement values of the 3rd [3] and 4th [4] layers were apparently higher in part [c] and part [a]. Therefore, the mountainous characteristics of part [b] and its geographical characteristics should be considered as an important factor when attempting to discriminate separate layers of aeolian dust from other layers of aerosols. In general, AOT retrieval can represent the strong seasonal and geographical variations in the dust deposition rates and their regional distribution. However, the possibilities to further our knowledge of dust deposition rates and frequencies in a high spatio-temporal resolution are limited so significant uncertainties remain, due to the methodological limitations of these remote sensing approaches. Finally yet importantly, concluded the essentiality of ground observation methods. Although high spatial resolution products with a chronological record are suitable basics for the improvement of dust deposition analyses and ecosystem effect assessments, ground surveys are still a key point for analyzing airborne deposition. However, deposition rate based on space model algorithms (AOT) remain the method of choice, even though they are relatively complicated and less accurate than ground observations (GDR), due to the lack of continuous atmospheric data at required scale over the area of interest.
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Dust deposition during the Early Holocene on the loess plateaus of the Vojvodina region in Northern Serbia

Dust deposition during the Early Holocene on the loess plateaus of the Vojvodina region in Northern Serbia

Dust deposition during the Early Holocene on the loess plateaus of the Vojvodina region in Northern Serbia Slobodan Markovic (1), Alida Timar-Gabor (2), Thomas Stevens (3), Zhengtang Guo (4), Qingzhen Hao (4), Yang Song (4), Ulrich Hambach (5), Frank Lehmkuhl (6), Zoran Peric (1), Igor Obreht (6), Christian Zeeden (6), Daniel Veres (7,2), and Milivoj Gavrilov (1)

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Composition and mixing state of atmospheric aerosols determined by electron microscopy: method development and application to aged Saharan dust deposition in the Caribbean boundary layer

Composition and mixing state of atmospheric aerosols determined by electron microscopy: method development and application to aged Saharan dust deposition in the Caribbean boundary layer

In the paper “Composition and mixing state of atmo- spheric aerosols determined by electron microscopy: method development and application to aged Saharan dust deposition in the Caribbean boundary layer” by K. Kandler et al. (2018) an incorrect version of Fig. 9 was published.

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Process-understanding of the impact of dust deposition on marine primary production

Process-understanding of the impact of dust deposition on marine primary production

There is still considerable debate surrounding the drivers of this variation in solubility with four main possibilities; i atmospheric chemical processing during dust transport Fan et al[r]

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Gutenberg Open Science: Mineral dust mobilisation, transport, and deposition in different climate epochs

Gutenberg Open Science: Mineral dust mobilisation, transport, and deposition in different climate epochs

First of all, due to the selection criteria for the trajectories, there are differences between the Eulerian and Lagrangian results in dust emission regions where no or only few trajectories pass, e.g., in Central Asia or South Africa. The focus, however, is on North Africa, the adjacent Atlantic Ocean, the northern part of South America, and the Caribbean. In these regions many Eulerian features are well represented by the trajectories. The horizontal distributions and absolute values of the Eulerian and Lagrangian data agree very well. The seasonal cycle is visible in both data sets, with dust reaching the southern part of the Amazon Basin south of the equator in DJF (Figs. 4.14a,b) and MAM (Figs. 4.14c,d) and the more zonal transport to the Caribbean in JJA (Figs. 4.14e,f) and SON (Figs. 4.14g,h). Also smaller scale features are comparable, like two “emission holes” in the central Sahara around 25 ◦ N, 5 ◦ E and 20 ◦ N, 15 ◦ E, which are best visible in JJA. These “holes” with negative net dust emission correspond to the Hoggar and the Tibesti Mountains where the soil conditions inhibit dust emission and dust from the surrounding source regions is deposited. The highest negative values are downstream of and fairly close to the prominent dust emission regions, showing the fast settling of large particles shortly after the emission. In all seasons the Lagrangian method slightly overestimates the dust deposition southwest of the Mali/Mauritania emission region. This indicates that dust, removed from the trajectories in this region, is gained by other air masses and transported further, which is not captured by the Lagrangian method. The distribution and absolute values of the dust emission at the Bod´ el´ e Depression and the deposition downstream coincide very well in the Eulerian and Lagrangian data. In DJF, MAM, and SON the dust is mainly transported to the south and southwest. In JJA the ITCZ is positioned north of the Bod´ el´ e Depression and dust emitted there is transported northwards to the Tibesti Mountains, causing the strong negative values there (Figs. 4.14e,f).
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Dust storms, dust transfer and depositions in the southern Aral Sea region

Dust storms, dust transfer and depositions in the southern Aral Sea region

The spatial and temporal distribution of the dust deposition was analyzed using passive deposition sampler installed in seven stations in the southern Aral Sea region: Muynak, Jaslyk, Takhiatash, Yangibazar, Beruniy and Buzubay. The sampler design was kept simple to ensure the longevity required for this long-term measurement program. Each sampler consists of a plastic tray (diameter 23cm) as a dust and sand sink, filled with artificial grass. Both monthly dust samples and dust samples of dust storm events have been collected. Soil samples were collected in 2011, at six measuring stations, with exception of Buzubay. Samples were
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Field comparison of dry deposition samplers for collection of atmospheric mineral dust: results from single-particle characterization

Field comparison of dry deposition samplers for collection of atmospheric mineral dust: results from single-particle characterization

As known from previous studies, the total deposition rate was dominated by coarse particles (8–16 µm). A high tempo- ral daily variability in total dust deposition rate was observed. The size-resolved deposition rate measurements of different passive samplers varied significantly between the samplers under the same conditions. This was in principle expected from the different sampler construction. Applying suitable deposition velocity models, atmospheric concentrations were calculated from different sampler deposition rates. The re- sulting concentrations on average are in better agreement be- tween the samplers than the deposition rates. However, dis- crepancies beyond the measurement uncertainty remain un- explained by the deposition models, in particular with re- spect to dependency on wind speed, which is predicted by the models but not observed. The estimation of an appropriate deposition velocity from different models for calculating at- mospheric concentrations remains obviously a challenge. In particular, when considering the size-resolved deposition ve- locities and deposition rate ratios, great discrepancies show up. While for an integrated bulk measurement or the PM 10
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Determination of dust sources by analyzing the elements correlation within the dust

Determination of dust sources by analyzing the elements correlation within the dust

The southwestern and western provinces of Iran are heavily affected by aeolian dust deposition. Besides the results of weathering, soil formation processes and the elemental composition of soil surfaces are influenced by aeolian dust transport and deposition. In most cases, the source areas of the dust are not clear. After[1] it is possible to conclude the dust source areas from the dust elemental composition. Therefore this study’s objective is to analysis the elemental composition of dust samples, and the elemental correlations of 10 dust sampling stations in the southwestern Iran for the determination of the dust source areas. To begin with: monthly dust samples including event frequencies were collected in the south and west of Iran. As one might expect, the element concentration was determined using inductively coupled plasma mass spectrometry (ICP-MS). Dust event frequency (DEF) was recorded of course based on its reduction of visibility in the air and the CCME standard for particulate matter 2.5 (<1000m visibility and PM2.5). Accordingly, the associations of daily data
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Development of a technique for measuring atmospheric dry deposition and its application to mineral dust

Development of a technique for measuring atmospheric dry deposition and its application to mineral dust

The motion of mineral dust in the Earth system commonly referred as atmospheric dust cycle (Schepanski, 2018) and it generally consists of emission, transport and deposition processes (see Figure 4). Dust emission is based on complex interactions between the wind and the soil surface from which the dust is originating (Kok et al., 2012; Schepanski, 2018). Similarly dust transport, is the phenomena in the air, where the suspended dust particles are carried over within the atmospheric wind flow (Schepanski, 2018). Atmospheric dust deposition is a third process in atmospheric dust cycle in which dust particles are transported from the atmosphere onto Earth's surface (Osada et al., 2014; Seinfeld and Pandis, 2006). Different factors such as proprieties of the airborne dust particles, atmospheric flow conditions and the underlying surface characteristics are known to affect dust deposition process (Knippertz and Stuut, 2014; Schepanski, 2018). With respect to dust removal mechanisms, wet and dry pathways are the two mechanisms for atmospheric deposition to occur. Dry deposition refers to the removal of particles from atmosphere to surface through different mechanical processes such as diffusion, turbulent and Brownian transfer and by gravitational settling processes while through wet processes, particles are deposited on the earth’s surface mainly by means of rain snow or mist (Lovett, 1994; Osada et al., 2014; Vivanco et al., 2017). Dry deposition is believed to be the major deposition mechanism for mineral dust aerosol due to its mass is dominated by large particles (Textor et al., 2007), though the importance may vary depending on the local climate conditions (Prospero et al., 2010; Stuut et al., 2009). Globally, dry deposition contribute 65– 80% of the total dust deposition (Textor et al., 2007). Surface wind speeds and local land surface characteristics (e.g. soil texture, soil moisture, and vegetation cover) are among the
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Dust in the atmospheres of Brown Dwarfs

Dust in the atmospheres of Brown Dwarfs

Here something similar is simulated. The developed atmosphere with the actual ele- mental depletion is taken. At this instance of time the atmosphere is dust free. An artificial process is assumed that increases the elemental abundances up to 75% of the solar value, taking care of the metallicity raise in the core. The “enrichment front” originates from the interior moving outward with an assumed velocity of 1km/s ( ≈ typical observed turbulence velocity in Brown Dwarf atmospheres). The picture was inspired by a cell enriched with the previous depleted elements and is driven upward by convection and overshooting. This “cell” releases its material to the surounding gas leading to an increase of the formerly depleted elements. The released material initiates immediately a significant nucleation rate (cf. right wing of the distribution function in figure 5.8). Due to this larger number of dust grains their growth towards the “rainout” size took about 40 minutes. After the fall-out the condensing elements in the growth region are about 10% more depleted than before the incident.
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Saharan Mineral Dust Experiment 2008: Airborne observations of dust and biomass burning layers over Cape Verde

Saharan Mineral Dust Experiment 2008: Airborne observations of dust and biomass burning layers over Cape Verde

In total, ten mission flights were conducted from Cape Verde providing data of dust and biomass burning plumes. In all cases with both aerosol types, the biomass burning layers were observed above the dust layer. On average, the Saharan dust plumes were situated below 2 km altitude above sea level (a.s.l.). The biomass burning layers which were advected from central Africa covered the altitude range between 2 and 4-5 km.

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The impact of mineral dust on cloud formation during the Saharan dust event in April 2014 over Europe

The impact of mineral dust on cloud formation during the Saharan dust event in April 2014 over Europe

studies using remote sensing observations that there is a ro- bust correlation between the presence of mineral dust and the efficiency of ice formation, as well as the ice water content (IWC) in ice clouds (Seifert et al., 2010; Zhang et al., 2018; Zhao et al., 2018). In addition, there is also direct observa- tional evidence of mineral dust interacting with cloud mi- crophysics and dynamics inside dust-infused baroclinic cy- clone storm clouds, as affected cirrus shields present with a visible cumuliform texture, exceedingly low cloud-top tem- peratures and other peculiar optical properties indicative for the presence of small ice crystals (Fromm et al., 2016). Sim- ilar findings have emerged from model studies. For exam- ple, Lee and Penner (2010) found a positive correlation be- tween INP concentrations and ice particle number concen- trations, as well as ice water path (IWP), by considering ice nucleation of dust and black carbon in the GCE (Goddard Cumulus Ensemble) model. It is well known that dust par- ticle number concentrations can exceed the climatological mean value by a 100-fold over a wide tropospheric height range during a dust event (Hande et al., 2015). In most oper- ational NWP models, however, aerosol interactions are pa- rameterized using preset aerosol concentrations and char- acteristics (e.g., the Integrated Forecast System (IFS) radi- ation scheme uses aerosol climatology from Tegen et al., 1997, and cloud droplet and ice particle number concentra- tions are predefined according to an assumed aerosol back- ground; ECMWF, 2017). Obviously, these models are chal- lenged during those outbreaks and the forecast performance is found to be significantly reduced in the presence of mineral dust (Schumann et al., 2016). In the past, studies with inter- active dust modeling approaches were conducted to quantify the effects of desert dust on weather. Smoydzin et al. (2012) included cloud activation and ice nucleation of mineral dust (diagnostically by
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Qualitätsorientierte modellbasierte Prozessparameteroptimierung für das Fused Deposition Modeling

Qualitätsorientierte modellbasierte Prozessparameteroptimierung für das Fused Deposition Modeling

The subject of this thesis is therefore the quality-oriented model-based process parameter op- timization for the fused deposition modeling. The situation-dependent and flexible optimal set- ting of the process parameters is a central task for the realization of quality-optimized produc- tion systems. The main idea of the presented solution is to implement an application-specific combination of black box and white box models for a new grey box approach for several target variables, which allow the optimal parameter setting and adapt to changing conditions, such as new component geometries. Based on the analysis of the object areas optimization, mod- eling and additive manufacturing processes, the scope of the work is limited and the state of the art for the model-based optimization of additive manufacturing processes is specified. The resulting research gaps and consequently, the corresponding research questions are derived. Subsequently, different models are developed for the FDM technology for a total of four varia- bles with eight target factors. Black box models based on empirical data obtained from exper- iments of a statistical experimental design as well as white box models, which are derived on the basis of literature review and own considerations. These models are validated and com- bined to a grey box approach for each target value. The generated models are implemented in a simulation environment together with a suitable minimization algorithm and the entire con- cept is subsequently validated. Finally, the approach is generalized and thus, a procedure for the grey box modeling for compley technologies is derived.
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Qualitätsorientierte modellbasierte Prozessparameteroptimierung für das Fused Deposition Modeling

Qualitätsorientierte modellbasierte Prozessparameteroptimierung für das Fused Deposition Modeling

The subject of this thesis is therefore the quality-oriented model-based process parameter op- timization for the fused deposition modeling. The situation-dependent and flexible optimal set- ting of the process parameters is a central task for the realization of quality-optimized produc- tion systems. The main idea of the presented solution is to implement an application-specific combination of black box and white box models for a new grey box approach for several target variables, which allow the optimal parameter setting and adapt to changing conditions, such as new component geometries. Based on the analysis of the object areas optimization, mod- eling and additive manufacturing processes, the scope of the work is limited and the state of the art for the model-based optimization of additive manufacturing processes is specified. The resulting research gaps and consequently, the corresponding research questions are derived. Subsequently, different models are developed for the FDM technology for a total of four varia- bles with eight target factors. Black box models based on empirical data obtained from exper- iments of a statistical experimental design as well as white box models, which are derived on the basis of literature review and own considerations. These models are validated and com- bined to a grey box approach for each target value. The generated models are implemented in a simulation environment together with a suitable minimization algorithm and the entire con- cept is subsequently validated. Finally, the approach is generalized and thus, a procedure for the grey box modeling for compley technologies is derived.
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Mathematical modelling for dose deposition in photontherapy

Mathematical modelling for dose deposition in photontherapy

In the present chapter, the numerical schemes developped in the previous chapter are used, but they are interpreted here only as a numerical approach, assumed to be accurate enough, for [r]

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Mathematical modelling for dose deposition in photontherapy

Mathematical modelling for dose deposition in photontherapy

medium and its motion is computed (or approximated) based on the physics of the modeled interactions. This operation is repeated a large number of times and the final result is averaged [r]

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Deposition, Charakterisierung und Bandanpassung oxidischer Dünnschichtmaterialien zur Lichtabsorption

Deposition, Charakterisierung und Bandanpassung oxidischer Dünnschichtmaterialien zur Lichtabsorption

In Abbildung 7.2 sind Spektren der Rumpfniveau- und Valenzband-Emissionen von Pro- ben mit den Cu-Oxidationsstufen 0, +I sowie +II gezeigt. Die Spektren wurden zur besseren Darstellung normiert, wodurch jedoch die Informationen über die Intensitäts- verhältnisse verloren gehen. Bei der CuO-Messung handelt es sich um dieselbe Probe wie im zuvor gezeigten Übersichtsspektrum. Alle Schichten wurden ausgehend vom selben Target hergestellt. Im Falle der Cu-Schicht (schwarz) ist auffällig, dass sich trotz Deposition mit Argon noch immer geringe Mengen an Sauerstoff in der Probe befin- den. Dies zeigt sich auch in der Auger-Emissionslinie, welche eine Schulter bei einer Bindungsenergie von ca. 570 eV aufweist. Die Hauptemission der Auger-Linie ist für die Cu 2 O-Probe (grün) und die CuO-Probe (rot) stark verbreitert und im Falle von Cu 2 O stark bzw. für CuO leicht zu höheren Bindungsenergien verschoben. Dies ist in guter Übereinstimmung mit vergleichbaren Messungen aus der Literatur [12, 231, 232]. Das Cu 2p 3 /2 -Signal wird ebenfalls stark von einer Änderung des Oxidationszustandes beeinflusst. Neben einer verbreiterten Hauptemissionslinie für CuO unterscheiden sich die beiden Kupferoxide in ihrer charakteristischen Satellitenstruktur. Für CuO ist hier ein relativ scharfes Signal zu beobachten, welches als 2p 3 /2 (S) gekennzeichnet ist. Die- ser Satellit besitzt eine markante Schulter bei geringeren Bindungsenergien und findet im Folgenden bei der Auswertung von Grenzflächenexperimenten Verwendung. Die be-
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The Influence of Temperature Fluctuations on Dust Formation in  Dust Driven Winds of Asymptotic Giant Branch Stars

The Influence of Temperature Fluctuations on Dust Formation in Dust Driven Winds of Asymptotic Giant Branch Stars

the carbon is assumed to condensate to graphite clusters. The formation of carbon rich dust via PolyAromatic Hydrocarbons (PAH’s) cannot be investi- gated in the framework of this method, because the resulting grains are not likely to consist of similar monomers, which prevents the description via a distribution function of the form f (N, t). Already the description of dust nu- cleation via PAH’s would require the investigation of the chemical pathway leading to the critical cluster (see e.g. Goeres 1993), a task which goes well beyond the scope of this work. For the same reason, the method cannot be applied straight forward to an oxygen-rich situation, where dust formation takes place via inhomogeneous growth, and the need of keeping track of the stoichiometric composition of the grains, requires the use of a more sophis- ticated distribution function. (A deterministic self-consistent model of an O-rich AGB star is presented by Jeong et al. 2003, .)
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Waste and dust utilisation in shaft furnaces

Waste and dust utilisation in shaft furnaces

A special shaft furnace -OxiCup- similar to the cupola furnace has been developed to recover residues of steel industry such as iron^ and carbon- rich dusts and sludges containing zinc[r]

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Self-consistent Dust Modelling in Brown Dwarfs

Self-consistent Dust Modelling in Brown Dwarfs

Until now, the feedback on atmospheric structures has not yet been taken into account. The problem of coupling the dust formation and its impact on the radiation field and the energy balance is iteratively being solved using the stellar atmosphere code PHOENIX (Hauschildt & Baron, 1999) by solving the frequency dependent radiative transfer and the structure of the atmosphere in hydrostatic equilibrium. The self–consistent dust model by Woitke & Helling (2003, 2004) and Helling & Woitke (2006) for oxygen–rich dwarfs builds upon an atmospheric structure and provides properties of the dust clouds, which, in turn, allows calculating dust opacities as input for the radiative transfer problem. Atmosphere models with dust consisting of solid TiO 2 , Mg 2 SiO 4 , SiO 2 , Fe, Al 2 O 3 , MgO, and MgSiO 3 for effective temperatures of 1500 . . . 3000 K (corresponding to late–type objects of spectral type M and L) are presented here.
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