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1
Fiedler, V., F. Arnold, S. Ludmann, A. Minikin, T. Hamburger, L. Pirjola, A. Dörnbrack, and H. Schlager. "African biomass burning plumes over the Atlantic: aircraft based measurements and implications for H<sub>2</sub>SO<sub>4</sub> and HNO<sub>3</sub> mediated smoke particle activation." Atmospheric Chemistry and Physics 11, no. 7 (April 5, 2011): 3211–25. http://dx.doi.org/10.5194/acp-11-3211-2011.
Abstract:
Abstract. Airborne measurements of trace gases and aerosol particles have been made in two aged biomass burning (BB) plumes over the East Atlantic (Gulf of Guinea). The plumes originated from BB in the Southern-Hemisphere African savanna belt. On the day of our measurements (13 August 2006), the plumes had ages of about 10 days and were respectively located in the middle troposphere (MT) at 3900–5500 m altitude and in the upper troposphere (UT) at 10 800–11 200 m. Probably, the MT plume was lifted by dry convection and the UT plume was lifted by wet convection. In the more polluted MT-plume, numerous measured trace species had markedly elevated abundances, particularly SO2 (up to 1400 pmol mol−1), HNO3 (5000–8000 pmol mol−1) and smoke particles with diameters larger than 270 nm (up to 2000 cm−3). Our MT-plume measurements indicate that SO2 released by BB had not experienced significant loss by deposition and cloud processes but rather had experienced OH-induced conversion to gas-phase sulfuric acid. By contrast, a significant fraction of the released NOy had experienced loss, most likely as HNO3 by deposition. In the UT-plume, loss of NOy and SO2 was more pronounced compared to the MT-plume, probably due to cloud processes. Building on our measurements and accompanying model simulations, we have investigated trace gas transformations in the ageing and diluting plumes and their role in smoke particle processing and activation. Emphasis was placed upon the formation of sulfuric acid and ammonium nitrate, and their influence on the activation potential of smoke particles. Our model simulations reveal that, after 13 August, the lower plume traveled across the Atlantic and descended to 1300 m and hereafter ascended again. During the travel across the Atlantic, the soluble mass fraction of smoke particles and their mean diameter increased sufficiently to allow the processed smoke particles to act as water vapor condensation nuclei already at very low water vapor supersaturations of only about 0.04%. Thereby, aged smoke particles had developed a potential to act as water vapor condensation nuclei in the formation of maritime clouds.
2
Fiedler, V., F. Arnold, S. Ludmann, A. Minikin, L. Pirjola, A. Dörnbrack, and H. Schlager. "African biomass burning plumes over the Atlantic: aircraft based measurements and implications for H<sub>2</sub>SO<sub>4</sub> and HNO<sub>3</sub> mediated smoke particle activation." Atmospheric Chemistry and Physics Discussions 10, no. 3 (March 25, 2010): 7699–743. http://dx.doi.org/10.5194/acpd-10-7699-2010.
Abstract:
Abstract. Airborne measurements of trace gases and aerosol particles have been made in two aged biomass burning (BB) plumes over the East Atlantic (Gulf of Guinea). The plumes originated from BB in the Southern Hemisphere African savanna belt. On the day of our measurements (13 August 2006), the plumes had ages of about 10 days and were respectively located in the middle troposphere (MT) at about 3000–5500 m altitude and in the upper troposphere (UT) at about 10 800–11 200 m. In the more polluted MT-plume, numerous measured trace species had markedly elevated abundances, particularly HNO3 (5000–8000 pmol/mol), SO2 (up to 1400 pmol/mol), and smoke particles with diameters larger than 250 nm (up to 2000 cm−3). Our MT-plume measurements indicate that SO2 released by BB had not experienced significant loss by deposition and cloud processes but rather had experienced OH-induced conversion to gas-phase sulfuric acid. By contrast, a large fraction of the released NOx had experienced loss, most likely as HNO3, by cloud processes and deposition. In the UT-plume, loss of NOy and SO2 by cloud processes and deposition was more pronounced compared to the MT-plume. Building on our measurements and accompanying model simulations, we have investigated trace gas transformations in the ageing and diluting plumes and their role in smoke particle processing and activation. Emphasis was placed upon the formation of sulfuric acid, nitric acid, and ammonium nitrate, and their influence on the activation potential of smoke particles. Our model simulations reveal that, after 13 August, the lower plume traveled across the Atlantic and descended to 1300 m and hereafter ascended again. During the travel across the Atlantic, the smoke particle mean diameter and sulfuric acid mass fraction increased sufficiently to allow the processed smoke particles to act as water vapor condensation nuclei already at very low water vapor supersaturations of only about 0.04%. Thereby, aged smoke particles had developed a potential to act as water vapor condensation nuclei in the formation of maritime clouds, including not only cumulus but even stratiform clouds.
3
Serra, P., J. Palau, M. Varela, J. Esteve, and J. L. Morenza. "Characterization of hydroxyapatite laser ablation plumes by fast intensified CCD-imaging." Journal of Materials Research 10, no. 2 (February 1995): 473–78. http://dx.doi.org/10.1557/jmr.1995.0473.
Abstract:
ArF excimer laser pulses (193 nm, 20 ns, 150 mJ) have been focused on a hydroxyapatite (HA) target in similar conditions to those normally used for thin film deposition. Fast intensified CCD images of HA laser ablation plumes have been taken in vacuum and under different water vapor pressures ranging from 0.01 mbar to 1 mbar. Images of HA ablation in vacuum have shown a plume freely expanding at a constant velocity of 2.3 × 106 cm/s. HA ablation under a water vapor pressure of 0.01 mbar has revealed an expansion behavior very similar to that of ablation in vacuum. Images taken under a water vapor pressure of 0.1 mbar have shown the formation of a shock structure in the plume. Finally, HA ablation under a water vapor pressure of 1 mbar has revealed the development of some irregularities in the shape of the plume.
4
Zhu, Xiaojing, Weihui Xu, Weishu Wang, Xu Shi, Gang Chen, and Shifei Zhao. "The Design of a Vapor-Condensing Plume Abatement System and Devices for Mechanical Draft Cooling Towers." Water 12, no. 4 (April 2, 2020): 1013. http://dx.doi.org/10.3390/w12041013.
Abstract:
Cooling towers are widely used in many fields, but the generation of visible plumes has a serious impact on the environment. Moreover, the evaporation losses also cause a great waste of water. In this paper, a vapor-condensing plume abatement system was designed for a mechanical-draft cooling tower based on the mechanism of vapor plume generation. An effective method to achieve water-saving and eliminate the water fog generated in the cooling tower was proposed, and its feasibility was verified by using thermodynamic analysis. Next, the vapor-condensing plume abatement device was designed and used for both the confined space cooling tower (CSCT) and the free space cooling tower (FSCT). The surface type heat exchanger was adopted to design the vapor-condensing plume abatement device. Then a basic calculation flow and method were proposed to obtain thermodynamic operating parameters. According to the comparison between the results of theoretical calculation and practical engineering application, it was found that the designed vapor-condensing plume abatement system obviously benefits the water-saving of a mechanical-draft cooling tower and considerable economic benefits can be obtained. The contents presented provide the theoretical basis and technical support for the upgrade of the cooling tower and the design of the new cooling tower.
5
Celik, Siddika, Frank Drewnick, Friederike Fachinger, James Brooks, Eoghan Darbyshire, Hugh Coe, Jean-Daniel Paris, et al. "Influence of vessel characteristics and atmospheric processes on the gas and particle phase of ship emission plumes: in situ measurements in the Mediterranean Sea and around the Arabian Peninsula." Atmospheric Chemistry and Physics 20, no. 8 (April 22, 2020): 4713–34. http://dx.doi.org/10.5194/acp-20-4713-2020.
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Abstract. A total of 252 emission plumes of ships operating in the Mediterranean Sea and around the Arabian Peninsula were investigated using a comprehensive dataset of gas- and submicron-particle-phase properties measured during the 2-month shipborne AQABA (Air Quality and Climate Change in the Arabian Basin) field campaign in summer 2017. The post-measurement identification of the corresponding ship emission events in the measured data included the determination of the plume sources (up to 38 km away) as well as the plume ages (up to 115 min) and was based on commercially available historical records of the Automatic Identification System. The dispersion lifetime of chemically inert CO2 in the ship emission plumes was determined as 70±15 min, resulting in levels indistinguishable from the marine background after 260±60 min. Emission factors (EFs) as quantities that are independent of plume dilution were calculated and used for the investigation of influences on ship emission plumes caused by ship characteristics and the combustion process as well as by atmospheric processes during the early stage of exhaust release and during plume ageing. Combustion efficiency and therefore emission factors of black carbon and NOx were identified to depend mostly on the vessel speed and gross tonnage. Moreover, larger ships, associated with higher engine power, were found to use fuel with higher sulfur content and have higher gas-phase SO2, particulate sulfate, particulate organics, and particulate matter EFs. Despite the independence of EFs of dilution, a significant influence of the ambient wind speed on the particle number and mass EFs was observed that can be traced back to enhanced particle coagulation in the case of slower dilution and suppressed vapour condensation on particles in the case of faster dilution of the emission plume. Atmospheric reactions and processes in ship emission plumes were investigated that include NOx and O3 chemistry, gas-to-particle conversion of NOx and SO2, and the neutralisation of acids in the particle phase through the uptake of ambient gas-phase ammonia, the latter two of which cause the inorganic particulate content to increase and the organic fraction to decrease with increasing plume age. The results allow for us to describe the influences on (or processes in) ship emission plumes quantitatively by parameterisations, which could be used for further refinement of atmospheric models, and to identify which of these processes are the most important ones.
6
Devenish, B. J., and J. M. Edwards. "Large-eddy simulation of the plume generated by the fire at the Buncefield oil depot in December 2005." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 465, no. 2102 (October 14, 2008): 397–419. http://dx.doi.org/10.1098/rspa.2008.0288.
Abstract:
The explosion at the Buncefield oil depot in Hertfordshire, UK on 11 December 2005 produced the largest fire in Europe since the Second World War. The magnitude of the fire and the scale of the resulting plume thus present a stringent test of any mathematical model of buoyant plumes. A large-eddy simulation of the Boussinesq equations with suitable initial conditions is shown to reproduce the characteristics of the observed plume; both the height of the plume above the source and the direction of the downwind spread agree with the observations. This supports the use of the Boussinesq assumption, even for such a powerful plume as the one generated by the Buncefield fire. The presence of a realistic water vapour profile does not lead to significant additional latent heating of the plume, but does lead to a small increase in the final rise height of the plume due to the increased buoyancy provided by the water vapour. Our simulations include the interaction of radiation with the aerosol in the plume, and reproduce the observed optical thickness of the plume and the reduction of solar radiation reaching the ground. Far downwind of the source, solar radiation is shown to play a role in lofting the laterally spreading plume, but the manner in which it does so depends on the aerosol concentration. In the case of high aerosol concentration, the thickness of the plume increases; the incoming solar radiation is absorbed over such a small depth that only the top of the plume is lofted upwards and the level of maximum concentration remains almost unchanged relative to the case with no radiation. When the aerosol concentration is low, the whole plume is heated by the incoming solar radiation and the lofting is more coherent, with the result that the level of maximum concentration increases relative to the case with no radiation, but the thickness of the plume increases only slightly.
7
Zhuang, Jiawei, Daniel J. Jacob, and Sebastian D. Eastham. "The importance of vertical resolution in the free troposphere for modeling intercontinental plumes." Atmospheric Chemistry and Physics 18, no. 8 (May 2, 2018): 6039–55. http://dx.doi.org/10.5194/acp-18-6039-2018.
Abstract:
Abstract. Chemical plumes in the free troposphere can preserve their identity for more than a week as they are transported on intercontinental scales. Current global models cannot reproduce this transport. The plumes dilute far too rapidly due to numerical diffusion in sheared flow. We show how model accuracy can be limited by either horizontal resolution (Δx) or vertical resolution (Δz). Balancing horizontal and vertical numerical diffusion, and weighing computational cost, implies an optimal grid resolution ratio (Δx ∕ Δz)opt ∼ 1000 for simulating the plumes. This is considerably higher than current global models (Δx ∕ Δz ∼ 20) and explains the rapid plume dilution in the models as caused by insufficient vertical resolution. Plume simulations with the Geophysical Fluid Dynamics Laboratory Finite-Volume Cubed-Sphere Dynamical Core (GFDL-FV3) over a range of horizontal and vertical grid resolutions confirm this limiting behavior. Our highest-resolution simulation (Δx ≈ 25 km, Δz ≈ 80 m) preserves the maximum mixing ratio in the plume to within 35 % after 8 days in strongly sheared flow, a drastic improvement over current models. Adding free tropospheric vertical levels in global models is computationally inexpensive and would also improve the simulation of water vapor.
8
Kiefer, Caroline M., Craig B. Clements, and Brian E. Potter. "Application of a Mini Unmanned Aircraft System for In Situ Monitoring of Fire Plume Thermodynamic Properties." Journal of Atmospheric and Oceanic Technology 29, no. 3 (March 1, 2012): 309–15. http://dx.doi.org/10.1175/jtech-d-11-00112.1.
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Abstract Direct measurements of wildland fire plume properties are rare because of difficult access to regions near the fire front and plume. Moisture released from combustion, in addition to added heat, can enhance buoyancy and convection, influencing fire behavior. In this study, a mini unmanned aircraft system (miniUAS) was used to obtain in situ measurements of temperature and relative humidity during a prescribed fire. The miniUAS was successfully maneuvered through the plume and its associated turbulence and provided observations of temperature and humidity profiles from near the centerline of the plume. Within the plume, the water vapor mixing ratio increased by 0.5–3.5 g kg−1 above ambient and was caused by the combustion of fuels. Potential temperature perturbations were on the order of 2–5 K. These results indicate that significant moisture and temperature enhancement can occur and may potentially modify convection dynamics of fire plumes.
9
Bian, Qijing, Shantanu H. Jathar, John K. Kodros, Kelley C. Barsanti, Lindsay E. Hatch, Andrew A. May, Sonia M. Kreidenweis, and Jeffrey R. Pierce. "Secondary organic aerosol formation in biomass-burning plumes: theoretical analysis of lab studies and ambient plumes." Atmospheric Chemistry and Physics 17, no. 8 (April 28, 2017): 5459–75. http://dx.doi.org/10.5194/acp-17-5459-2017.
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Abstract. Secondary organic aerosol (SOA) has been shown to form in biomass-burning emissions in laboratory and field studies. However, there is significant variability among studies in mass enhancement, which could be due to differences in fuels, fire conditions, dilution, and/or limitations of laboratory experiments and observations. This study focuses on understanding processes affecting biomass-burning SOA formation in laboratory smog-chamber experiments and in ambient plumes. Vapor wall losses have been demonstrated to be an important factor that can suppress SOA formation in laboratory studies of traditional SOA precursors; however, impacts of vapor wall losses on biomass-burning SOA have not yet been investigated. We use an aerosol-microphysical model that includes representations of volatility and oxidation chemistry to estimate the influence of vapor wall loss on SOA formation observed in the FLAME III smog-chamber studies. Our simulations with base-case assumptions for chemistry and wall loss predict a mean OA mass enhancement (the ratio of final to initial OA mass, corrected for particle-phase wall losses) of 1.8 across all experiments when vapor wall losses are modeled, roughly matching the mean observed enhancement during FLAME III. The mean OA enhancement increases to over 3 when vapor wall losses are turned off, implying that vapor wall losses reduce the apparent SOA formation. We find that this decrease in the apparent SOA formation due to vapor wall losses is robust across the ranges of uncertainties in the key model assumptions for wall-loss and mass-transfer coefficients and chemical mechanisms.We then apply similar assumptions regarding SOA formation chemistry and physics to smoke emitted into the atmosphere. In ambient plumes, the plume dilution rate impacts the organic partitioning between the gas and particle phases, which may impact the potential for SOA to form as well as the rate of SOA formation. We add Gaussian dispersion to our aerosol-microphysical model to estimate how SOA formation may vary under different ambient-plume conditions (e.g., fire size, emission mass flux, atmospheric stability). Smoke from small fires, such as typical prescribed burns, dilutes rapidly, which drives evaporation of organic vapor from the particle phase, leading to more effective SOA formation. Emissions from large fires, such as intense wildfires, dilute slowly, suppressing OA evaporation and subsequent SOA formation in the near field. We also demonstrate that different approaches to the calculation of OA enhancement in ambient plumes can lead to different conclusions regarding SOA formation. OA mass enhancement ratios of around 1 calculated using an inert tracer, such as black carbon or CO, have traditionally been interpreted as exhibiting little or no SOA formation; however, we show that SOA formation may have greatly contributed to the mass in these plumes.In comparison of laboratory and plume results, the possible inconsistency of OA enhancement between them could be in part attributed to the effect of chamber walls and plume dilution. Our results highlight that laboratory and field experiments that focus on the fuel and fire conditions also need to consider the effects of plume dilution or vapor losses to walls.
10
Ramamurthi, Divya, Cindy Chau, and Robert K. Jackler. "JUUL and other stealth vaporisers: hiding the habit from parents and teachers." Tobacco Control 28, no. 6 (September 15, 2018): 610–16. http://dx.doi.org/10.1136/tobaccocontrol-2018-054455.
Abstract:
BackgroundSome consumers wish to use vapour devices discreetly so that family members, teachers and coworkers do not recognise their use of nicotine ortetrahydrocannabinol (THC) laden vapour.MethodsStealthy vapour devices, as well as low-odour and low-vapour e-juices, were identified via a comprehensive online search between March and June 2018.ResultsAs evidence of their popularity, a search for ‘stealth vaping’ on YouTube found 18 200 videos. A variety of cleverly designed vapour devices disguised as USB sticks, pens, remote controls, car fobs, smart phones, sweatshirt drawstrings and even asthma inhalers are on the market. JUUL, which resembles a USB stick, is the archetype of these devices and is especially popular among youth. A search of ‘JUUL’ on YouTube yielded 148 000 videos with 57 videos having >100 000 views. Searches on ‘JUUL at school’ (15 500), ‘JUUL in class’ (6840), ‘hiding JUUL in school’ (2030) and ‘JUUL in school bathroom’ (1040) illustrate the product’s popularity among students. Some e-juices promote themselves as having low visibility plumes while others profess to be of subtle odour to avoid detection. Numerous techniques have been described to hide the exhaled vapour plume such as by swallowing it or blowing it into one’s clothing or into a backpack.ConclusionsThe vaping industry has demonstrated much ingenuity in devising discreet vaporisers and de-emphasising exhaled vapour plumes and their aroma. The US market for vaping devices with stealthy characteristics is anything but inconspicuous, with JUUL alone accounting for 70.5% of sales (July 2018).
11
Real, E., K. Law, H. Schlager, A. Roiger, H. Huntrieser, J. Methven, M. Cain, et al. "Lagrangian analysis of low level anthropogenic plume processing across the North Atlantic." Atmospheric Chemistry and Physics Discussions 8, no. 2 (April 17, 2008): 7509–54. http://dx.doi.org/10.5194/acpd-8-7509-2008.
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Abstract. The photochemical evolution of an anthropogenic plume from the New-York/Boston region during its transport at low altitudes over the North Atlantic to the European west coast has been studied using a Lagrangian framework. This plume, originally strongly polluted, was sampled by research aircraft just off the North American east coast on 3 successive days, and 3 days downwind off the west coast of Ireland where another aircraft re-sampled a weakly polluted plume. Changes in trace gas concentrations during transport were reproduced using a photochemical trajectory model including deposition and mixing effects. Chemical and wet deposition processing dominated the evolution of all pollutants in the plume. The mean net O3 production was evaluated to be -5 ppbv/day leading to low values of O3 by the time the plume reached Europe. Wet deposition of nitric acid was responsible for an 80% reduction in this O3 production. If the plume had not encountered precipitation, it would have reached the Europe with O3 levels up to 80-90 ppbv, and CO levels between 120 and 140 ppbv. Photochemical destruction also played a more important role than mixing in the evolution of plume CO due to high levels of both O3 and water vapour showing that CO cannot always be used as a tracer for polluted air masses, especially for plumes transported at low altitudes. The results also show that, in this case, an important increase in the O3/CO slope can be attributed to chemical destruction of CO and not to photochemical O3 production as is often assumed.
12
Prata, Fred, Stefano Corradini, Riccardo Biondi, Lorenzo Guerrieri, Luca Merucci, Andrew Prata, and Dario Stelitano. "Applications of Ground-Based Infrared Cameras for Remote Sensing of Volcanic Plumes." Geosciences 14, no. 3 (March 17, 2024): 82. http://dx.doi.org/10.3390/geosciences14030082.
Abstract:
Ground-based infrared cameras can be used effectively and safely to provide quantitative information about small to moderate-sized volcanic eruptions. This study describes an infrared camera that has been used to measure emissions from the Mt. Etna and Stromboli (Sicily, Italy) volcanoes. The camera provides calibrated brightness temperature images in a broadband (8–14 µm) channel that is used to determine height, plume ascent rate and volcanic cloud/plume temperature and emissivity at temporal sampling rates of up to 1 Hz. The camera can be operated in the field using a portable battery and includes a microprocessor, data storage and WiFi. The processing and analyses of the data are described with examples from the field experiments. The updraft speeds of the small eruptions at Stromboli are found to decay with a timescale of ∼10 min and the volcanic plumes reach thermal equilibrium within ∼2 min. A strong eruption of Mt. Etna on 1 April 2021 was found to reach ∼9 km, with ascent speeds of 10–20 ms−1. The plume, mostly composed of the gases CO2, water vapour and SO2, became bent over by the prevailing winds at high levels, demonstrating the need for multiple cameras to accurately infer plume heights.
13
Real, E., K. S. Law, H. Schlager, A. Roiger, H. Huntrieser, J. Methven, M. Cain, et al. "Lagrangian analysis of low altitude anthropogenic plume processing across the North Atlantic." Atmospheric Chemistry and Physics 8, no. 24 (December 23, 2008): 7737–54. http://dx.doi.org/10.5194/acp-8-7737-2008.
Abstract:
Abstract. The photochemical evolution of an anthropogenic plume from the New-York/Boston region during its transport at low altitudes over the North Atlantic to the European west coast has been studied using a Lagrangian framework. This plume, originally strongly polluted, was sampled by research aircraft just off the North American east coast on 3 successive days, and then 3 days downwind off the west coast of Ireland where another aircraft re-sampled a weakly polluted plume. Changes in trace gas concentrations during transport are reproduced using a photochemical trajectory model including deposition and mixing effects. Chemical and wet deposition processing dominated the evolution of all pollutants in the plume. The mean net photochemical O3 production is estimated to be −5 ppbv/day leading to low O3 by the time the plume reached Europe. Model runs with no wet deposition of HNO3 predicted much lower average net destruction of −1 ppbv/day O3, arising from increased levels of NOx via photolysis of HNO3. This indicates that wet deposition of HNO3 is indirectly responsible for 80% of the net destruction of ozone during plume transport. If the plume had not encountered precipitation, it would have reached Europe with O3 concentrations of up to 80 to 90 ppbv and CO between 120 and 140 ppbv. Photochemical destruction also played a more important role than mixing in the evolution of plume CO due to high levels of O3 and water vapour showing that CO cannot always be used as a tracer for polluted air masses, especially in plumes transported at low altitudes. The results also show that, in this case, an increase in O3/CO slopes can be attributed to photochemical destruction of CO and not to photochemical O3 production as is often assumed.
14
Sahany, Sandeep, J. David Neelin, Katrina Hales, and Richard B. Neale. "Temperature–Moisture Dependence of the Deep Convective Transition as a Constraint on Entrainment in Climate Models." Journal of the Atmospheric Sciences 69, no. 4 (March 30, 2012): 1340–58. http://dx.doi.org/10.1175/jas-d-11-0164.1.
Abstract:
Abstract Properties of the transition to strong deep convection, as previously observed in satellite precipitation statistics, are analyzed using parcel stability computations and a convective plume velocity equation. A set of alternative entrainment assumptions yields very different characteristics of the deep convection onset boundary (here measured by conditional instability and plume vertical velocity) in a bulk temperature–water vapor thermodynamic plane. In observations the threshold value of column water vapor above which there is a rapid increase in precipitation, referred to as the critical value, increases with temperature, but not as quickly as column saturation, and this can be matched only for cases with sufficiently strong entrainment. This corroborates the earlier hypothesis that entraining plumes can explain this feature seen in observations, and it places bounds on the lower-tropospheric entrainment. Examination of a simple interactive entrainment scheme in which a minimum turbulent entrainment is enhanced by a dynamic entrainment (associated with buoyancy-induced vertical acceleration) shows that the deep convection onset curve is governed by the prescribed minimum entrainment. Results from a 0.5° resolution version of the Community Climate System Model, whose convective parameterization includes substantial entrainment, yield a reasonable match to satellite observations in several respects. Temperature–water vapor dependence is seen to agree well with the plume calculations and with offline simulations performed using the convection scheme of the model. These findings suggest that the convective transition characteristics, including the onset curve in the temperature–water vapor plane, can provide a substantial constraint for entrainment assumptions used in climate model deep convective parameterizations.
15
Unterstrasser, S., and A. Stephan. "Far field wake vortex evolution of two aircraft formation flight and implications on young contrails." Aeronautical Journal 124, no. 1275 (January 31, 2020): 667–702. http://dx.doi.org/10.1017/aer.2020.3.
Abstract:
AbstractLarge-eddy simulations (LES) have been employed to investigate the far-field four-vortex wake vortex evolution over 10min behind an aircraft formation. In formation flight scenarios, the wake vortex behaviour was found to be much more complex, chaotic and also diverse than in the classical single aircraft case, depending very sensitively on the formation geometry, i.e. the lateral and vertical offset of the two involved aircraft. Even though the case-by-case variability of the wake vortex behaviour across the various formation flight scenarios is large, the final plume dimensions after vortex dissolution are in general substantially different from those of single aircraft scenarios. The plumes are around 170 to 250m deep and 400m to 680m broad, whereas a single A350/B777 aircraft would produce a 480m deep and 330m broad plume. Formation flight plumes are thus not as deep, yet they are broader, as the vortices do not only propagate vertically but also in span-wise direction. Two different LES models have been employed independently and show consistent results suggesting the robustness of the findings. Notably, $CO_{2}$ emissions are only one contribution to the aviation climate impact among several others like contrails and emission of water vapour and nitrogen oxides, which would be all affected by the implementation of formation flight. Thus, we also highlight the differences in ice microphysical and geometrical properties of young formation flight contrails relative to the classical single aircraft case.
16
POVITSKY, ALEX. "FLUID DYNAMICS ISSUES IN SYNTHESIS OF CARBON NANOTUBES." International Journal of Nanoscience 04, no. 01 (February 2005): 73–98. http://dx.doi.org/10.1142/s0219581x0500295x.
Abstract:
The majority of carbon nanotubes' synthesis processes occur in the presence of fluid (liquid, gas, plasma, or multi-phase flow) that may function as a carrier of catalyst particles, feedstock of carbon, and the heating or cooling agent. The fluid motion defines the temperature of catalyst particles and the local chemical composition of the fluid that determines the success of synthesis of high-purity nanotubes. In this review paper, the laser ablation process, high-pressure carbon oxide process, and chemical vapor deposition process are considered from the prospective of fluid dynamics modeling. The multi-model approach should be used for concurrent rendering of different areas of computational domain by different models and/or different time steps for the same model. For multiple plume ejection in laser ablation, the near-target area could be rendered by molecular dynamics approach whereas continuous gas dynamics algorithms should be employed to simulate plume dynamics of previously ejected plumes apart of the target. Such an approach combines continuous mechanics of multi-species flow of feedstock gas or plume; micro-fluidic flow model that is needed to find heat and mass transfer rate to catalysts in presence of individual nanotubes in close proximity to each other; and molecular dynamics of evaporation and ejection of plume in laser ablation.
17
Randel, William J., Benjamin R. Johnston, John J. Braun, Sergey Sokolovskiy, Holger Vömel, Aurelien Podglajen, and Bernard Legras. "Stratospheric Water Vapor from the Hunga Tonga–Hunga Ha’apai Volcanic Eruption Deduced from COSMIC-2 Radio Occultation." Remote Sensing 15, no. 8 (April 20, 2023): 2167. http://dx.doi.org/10.3390/rs15082167.
Abstract:
The eruption of the Hunga Tonga–Hunga Ha’apai (HTHH) volcano on 15 January 2022 injected large amounts of water vapor (H2O) directly into the stratosphere. While normal background levels of stratospheric H2O are not detectable in radio occultation (RO) measurements, effects of the HTHH eruption are clearly observed as anomalous refractivity profiles from COSMIC-2, suggesting the possibility of detecting the HTHH H2O signal. To separate temperature and H2O effects on refractivity, we use co-located temperature observations from the Microwave Limb Sounder (MLS) to constrain a simplified H2O retrieval. Our results show enhancements of H2O up to ~2500–3500 ppmv in the stratosphere (~29–33 km) in the days following the HTHH eruption, with propagating patterns that follow the dispersing volcanic plume. The stratospheric H2O profiles derived from RO are in reasonable agreement with limited radiosonde observations over Australia. The H2O profiles during the first few days after the eruption show descent of the plume at a rate of ~−1 km/day, likely due to strong radiative cooling (~−10 K/day) induced by high H2O concentrations; slower descent (~−200 m/day) is observed over the following week as the plume disperses. The total mass of H2O injected by HTHH is estimated as 110 ± 14 Tg from measurements in the early plumes during 16–18 January, which equates to approximately 8% of the background global mass of stratospheric H2O. These RO measurements provide novel quantification of the unprecedented H2O amounts and the plume evolution during the first week after the HTHH eruption.
18
Thorpe, Andrew K., Christian Frankenberg, David R. Thompson, Riley M. Duren, Andrew D. Aubrey, Brian D. Bue, Robert O. Green, et al. "Airborne DOAS retrievals of methane, carbon dioxide, and water vapor concentrations at high spatial resolution: application to AVIRIS-NG." Atmospheric Measurement Techniques 10, no. 10 (October 19, 2017): 3833–50. http://dx.doi.org/10.5194/amt-10-3833-2017.
Abstract:
Abstract. At local scales, emissions of methane and carbon dioxide are highly uncertain. Localized sources of both trace gases can create strong local gradients in its columnar abundance, which can be discerned using absorption spectroscopy at high spatial resolution. In a previous study, more than 250 methane plumes were observed in the San Juan Basin near Four Corners during April 2015 using the next-generation Airborne Visible/Infrared Imaging Spectrometer (AVIRIS-NG) and a linearized matched filter. For the first time, we apply the iterative maximum a posteriori differential optical absorption spectroscopy (IMAP-DOAS) method to AVIRIS-NG data and generate gas concentration maps for methane, carbon dioxide, and water vapor plumes. This demonstrates a comprehensive greenhouse gas monitoring capability that targets methane and carbon dioxide, the two dominant anthropogenic climate-forcing agents. Water vapor results indicate the ability of these retrievals to distinguish between methane and water vapor despite spectral interference in the shortwave infrared. We focus on selected cases from anthropogenic and natural sources, including emissions from mine ventilation shafts, a gas processing plant, tank, pipeline leak, and natural seep. In addition, carbon dioxide emissions were mapped from the flue-gas stacks of two coal-fired power plants and a water vapor plume was observed from the combined sources of cooling towers and cooling ponds. Observed plumes were consistent with known and suspected emission sources verified by the true color AVIRIS-NG scenes and higher-resolution Google Earth imagery. Real-time detection and geolocation of methane plumes by AVIRIS-NG provided unambiguous identification of individual emission source locations and communication to a ground team for rapid follow-up. This permitted verification of a number of methane emission sources using a thermal camera, including a tank and buried natural gas pipeline.
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Miller, Steven D., Louie D. Grasso, Qijing Bian, Sonia M. Kreidenweis, Jack F. Dostalek, Jeremy E. Solbrig, Jennifer Bukowski, et al. "<i>A Tale of Two Dust Storms</i>: analysis of a complex dust event in the Middle East." Atmospheric Measurement Techniques 12, no. 9 (September 24, 2019): 5101–18. http://dx.doi.org/10.5194/amt-12-5101-2019.
Abstract:
Abstract. Lofted mineral dust over data-sparse regions presents considerable challenges to satellite-based remote sensing methods and numerical weather prediction alike. The southwest Asia domain is replete with such examples, with its diverse array of dust sources, dust mineralogy, and meteorologically driven lofting mechanisms on multiple spatial and temporal scales. A microcosm of these challenges occurred over 3–4 August 2016 when two dust plumes, one lofted within an inland dry air mass and another embedded within a moist air mass, met over the southern Arabian Peninsula. Whereas conventional infrared-based techniques readily detected the dry air mass dust plume, they experienced marked difficulties in detecting the moist air mass dust plume, becoming apparent when visible reflectance revealed the plume crossing over an adjacent dark water background. In combining information from numerical modeling, multi-satellite and multi-sensor observations of lofted dust and moisture profiles, and idealized radiative transfer simulations, we develop a better understanding of the environmental controls of this event, characterizing the sensitivity of infrared-based dust detection to column water vapor, dust vertical extent, and dust optical properties. Differences in assumptions of dust complex refractive index translate to variations in the sign and magnitude of the split-window brightness temperature difference commonly used for detecting mineral dust. A multi-sensor technique for mitigating the radiative masking effects of water vapor via modulation of the split-window dust-detection threshold, predicated on idealized simulations tied to these driving factors, is proposed and demonstrated. The new technique, indexed to an independent description of the surface-to-500 hPa atmospheric column moisture, reveals parts of the missing dust plume embedded in the moist air mass, with the best performance realized over land surfaces.
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Puretzky, A. A., D. B. Geohegan, G. B. Hurst, M. V. Buchanan, and B. S. Luk'yanchuk. "Imaging of Vapor Plumes Produced by Matrix Assisted Laser Desorption: A Plume Sharpening Effect." Physical Review Letters 83, no. 2 (July 12, 1999): 444–47. http://dx.doi.org/10.1103/physrevlett.83.444.
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Sorenson, Blake T., Jeffrey S. Reid, Jianglong Zhang, Robert E. Holz, William L. Smith Sr., and Amanda Gumber. "Thermal infrared observations of a western United States biomass burning aerosol plume." Atmospheric Chemistry and Physics 24, no. 2 (January 29, 2024): 1231–48. http://dx.doi.org/10.5194/acp-24-1231-2024.
Abstract:
Abstract. Biomass burning smoke particles, due to their submicron particle size in relation to the average thermal infrared (TIR) wavelength, theoretically have negligible signals at the TIR channels. However, nearly instantaneous longwave (LW) signatures of thick smoke plumes can be frequently observed at the TIR channels from remotely sensed data, including at 10.6 µm (IR window), as well as in water-vapor-sensitive wavelengths at 7.3, 6.8, and 6.3 µm (e.g., lower, middle, and upper troposphere). We systematically evaluated multiple hypotheses as to causal factors of these IR signatures of biomass burning smoke using a combination of data from the Aqua MODerate resolution Imaging Spectroradiometer (MODIS), Aqua Cloud and the Earth Radiant Energy System (CERES), Geostationary Operational Environmental Satellite 16/17 (GOES-16/17) Advanced Baseline Imager, and Suomi-NPP Visible Infrared Imaging Radiometer Suite (VIIRS) and Cross-track Infrared Sounder (CrIS). The largely clear transmission of light through wildfire smoke in the near infrared indicates that coarse or giant ash particles are unlikely to be the dominant cause. Rather, clear signals in water vapor and TIR channels suggest that both co-transported water vapor injected to the middle to upper troposphere and surface cooling by the reduction of surface radiation by the plume are more significant, with the surface cooling effect of smoke aloft being the most dominant. Giving consideration of the smoke impacts on TIR and longwave, CERES indicates that large wildfire aerosol plumes are more radiatively neutral. Further, this smoke-induced TIR signal may be used to map very optically thick smoke plumes, where traditional aerosol retrieval methods have difficulties.
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Gallagher, Neal B., Barry M. Wise, and David M. Sheen. "Error Analysis for Estimation of Trace Vapor Concentration Pathlength in Stack Plumes." Applied Spectroscopy 57, no. 6 (June 2003): 614–21. http://dx.doi.org/10.1366/000370203322005283.
Abstract:
Near-infrared hyperspectral imaging is finding utility in remote sensing applications such as detection and quantification of chemical vapor effluents in stack plumes. Optimizing the sensing system or quantification algorithms is difficult because reference images are rarely well characterized. The present work uses a radiance model for a down-looking scene and a detailed noise model for dispersive and Fourier transform spectrometers to generate well-characterized synthetic data. These data were used with a classical least-squares-based estimator in an error analysis to obtain estimates of different sources of concentration-pathlength quantification error in the remote sensing problem. Contributions to the overall quantification error were the sum of individual error terms related to estimating the background, atmospheric corrections, plume temperature, and instrument signal-to-noise ratio. It was found that the quantification error depended strongly on errors in the background estimate and second-most on instrument signal-to-noise ratio. Decreases in net analyte signal (e.g., due to low analyte absorbance or increasing the number of analytes in the plume) led to increases in the quantification error as expected. These observations have implications on instrument design and strategies for quantification. The outlined approach could be used to estimate detection limits or perform variable selection for given sensing problems.
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Wen, Qian, and Xiang Dong Gao. "Analysis of Characteristic of Metal Vapor Plume during High-Power Disc Laser Welding." Applied Mechanics and Materials 201-202 (October 2012): 1126–29. http://dx.doi.org/10.4028/www.scientific.net/amm.201-202.1126.
Abstract:
Metal vapor plume which induced during high power disc laser welding contains lots of information that related to the welding quality. Stainless steel 304 was taken as the experiment object for the high power disc laser welding experiment. A high-speed camera was used to capture the ultraviolet band and visible light band metal vapor plume images in the laser welding process. Image processing techniques such as median filtering, Wiener filtering, gray level threshold and image binarization were applied to get the images that only metal vapor plume was included. The ratio of the absolute value of coordinate difference between the centroid of plume and welding point was taken as the characteristic parameter. Welding experimental results and analysis of the changing of the ratio of the absolute value of coordinate difference between the centroid of plume and welding point confirmed that the welding quality could be monitored by the metal vapor plume during high power disc laser welding.
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Hamadi, Farida, and El Hachemi Amara. "Effect of Argon Ambient Gas Pressure on Plume Expansion Dynamics." Advanced Materials Research 227 (April 2011): 129–33. http://dx.doi.org/10.4028/www.scientific.net/amr.227.129.
Abstract:
In this paper we present a numerical modeling of a nanosecond laser pulse interaction with a titanium target. We investigate the vapor plume formation and the influence of the ambient gas pressure on plume expansion dynamics. The vapor plume formation depends on the results of the heat transfer in the solid target modeling. The solid-liquid phase change is modeled by a two dimensional approach using an enthalpy formulation. The resulting plume expansion in the argon background gas is studied using the species transport model. The algebraic equations are discretized by the finite volume method implemented by Fluent CFD software [1]. The calculation results of plume expansion velocity, density, temperature and degree of ionization in the plume are presented.
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Hansen, C. J. "Enceladus' Water Vapor Plume." Science 311, no. 5766 (March 10, 2006): 1422–25. http://dx.doi.org/10.1126/science.1121254.
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Popel, S. I., and A. A. Gisko. "Charged dust and shock phenomena in the Solar System." Nonlinear Processes in Geophysics 13, no. 2 (June 21, 2006): 223–29. http://dx.doi.org/10.5194/npg-13-223-2006.
Abstract:
Abstract. The results on shock phenomena in dusty plasmas of the Solar System are reviewed. The problems of dust ion acoustic bow shock in interaction of the solar wind with dusty cometary coma and formation of transient atmospheres of atmosphereless cosmic bodies such as Moon, Mercury, asteroids and comets are considered. The latter assumes the evolution of meteoroid impact plumes and production of charged dust grains due to the condensation of both the plume substance and the vapor thrown from the crater and the surrounding regolith layer. Physical phenomena occurring during large meteoroid impacts can be modeled with the aid of active rocket experiments, which involve the release of some gaseous substance in near-Earth space. New vistas in investigation of shock processes in natural dusty plasmas are determined.
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Narezo Guzman, Daniela, Tomasz Frączek, Christopher Reetz, Chao Sun, Detlef Lohse, and Guenter Ahlers. "Vapour-bubble nucleation and dynamics in turbulent Rayleigh–Bénard convection." Journal of Fluid Mechanics 795 (April 13, 2016): 60–95. http://dx.doi.org/10.1017/jfm.2016.178.
Abstract:
Vapour bubbles nucleating at micro-cavities etched into the silicon bottom plate of a cylindrical Rayleigh–Bénard sample (diameter $D=8.8$ cm, aspect ratio ${\it\Gamma}\equiv D/L\simeq 1.00$ where $L$ is the sample height) were visualized from the top and from the side. A triangular array of cylindrical micro-cavities (with a diameter of $30~{\rm\mu}\text{m}$ and a depth of $100~{\rm\mu}\text{m}$) covered a circular centred area (diameter of 2.5 cm) of the bottom plate. Heat was applied to the sample only over this central area while cooling was over the entire top-plate area. Bubble sizes and frequencies of departure from the bottom plate are reported for a range of bottom-plate superheats $T_{b}-T_{on}$ ($T_{b}$ is the bottom-plate temperature, $T_{on}$ is the onset temperature of bubble nucleation) from 3 to 12 K for three different cavity separations. The difference $T_{b}-T_{t}\simeq 16$ K between $T_{b}$ and the top plate temperature $T_{t}$ was kept fixed while the mean temperature $T_{m}=(T_{b}+T_{t})/2$ was varied, leading to a small range of the Rayleigh number $Ra$ from $1.4\times 10^{10}$ to $2.0\times 10^{10}$. The time between bubble departures from a given cavity decreased exponentially with increasing superheat and was independent of cavity separation. The contribution of the bubble latent heat to the total enhancement of heat transferred due to bubble nucleation was found to increase with superheat, reaching up to 25 %. The bubbly flow was examined in greater detail for a superheat of 10 K and $Ra\simeq 1.9\times 10^{10}$. The condensation and/or dissolution rates of departed bubbles revealed two regimes: the initial rate was influenced by steep thermal gradients across the thermal boundary layer near the plate and was two orders of magnitude larger than the final condensation and/or dissolution rate that prevailed once the rising bubbles were in the colder bulk flow of nearly uniform temperature. The dynamics of thermal plumes was studied qualitatively in the presence and absence of nucleating bubbles. It was found that bubbles enhanced the plume velocity by a factor of four or so and drove a large-scale circulation (LSC). Nonetheless, even in the presence of bubbles the plumes and LSC had a characteristic velocity which was smaller by a factor of five or so than the bubble-rise velocity in the bulk. In the absence of bubbles there was strongly turbulent convection but no LSC, and plumes on average rose vertically.
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Adrien, Muriel. "Pluie, vapeur et vitesse chez Turner." Cahiers victoriens et édouardiens, no. 71 Printemps (June 18, 2010): 167–84. http://dx.doi.org/10.4000/cve.2840.
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Rose, Clémence, Brice Foucart, David Picard, Aurélie Colomb, Jean-Marc Metzger, Pierre Tulet, and Karine Sellegri. "New particle formation in the volcanic eruption plume of the Piton de la Fournaise: specific features from a long-term dataset." Atmospheric Chemistry and Physics 19, no. 20 (October 28, 2019): 13243–65. http://dx.doi.org/10.5194/acp-19-13243-2019.
Abstract:
Abstract. New particle formation (NPF) is a key atmospheric process which may be responsible for a major fraction of the total aerosol number burden at the global scale, including in particular cloud condensation nuclei (CCN). NPF has been observed in various environments around the world, but some specific conditions, such as those encountered in volcanic plumes, remain poorly documented in the literature. Yet, understanding such natural processes is essential to better define pre-industrial conditions and their variability in climate model simulations. Here we report observations of NPF performed at the high-altitude observatory of Maïdo (2165 m a.s.l., La Réunion Island) between 1 January and 31 December 2015. During this time period, three effusive eruptions of the Piton de la Fournaise, located ∼39 km away from the station, were observed and documented, resulting in 29 d of measurement in volcanic plume conditions to be compared with 250 “non-plume days”. This dataset is, to our knowledge, the largest ever reported for the investigation of NPF in tropospheric volcanic plume conditions, and it allowed for the first time a statistical approach to characterize the process and also assessment of its relevance with respect to non-plume conditions. NPF was observed on 90 % of the plume days vs. 71 % of the non-plume days during the 4 months when the eruptions occurred. The events were on average detected earlier on plume days, most likely benefiting from larger amounts of precursors available at the site prior to nucleation hours. The overall effect of the plume conditions on the particle growth rate was limited. However, with the exception of September, particle formation rates were significantly higher on plume days. The signature of the volcanic plume on the aerosol spectra up to dp=600 nm was further investigated based on the analysis and fitting of the particle size distributions recorded under in-plume and off-plume conditions. The spectra recorded prior to nucleation hours, in the absence of freshly formed particles, featured a significant contribution of particles likely formed via heterogeneous processes at the vent of the volcano (and assimilated to volcanic primary particles) to the concentrations of the two accumulation modes on plume days. Later on in the morning, the concentrations of the nucleation and Aitken modes showed important variations on plume days compared to event days outside of plume conditions. The spectra recorded on event days, under in-plume and off-plume conditions, were further used to provide an average size distribution of the particles of volcanic origin, which clearly highlighted the dominant contribution of secondary over primary particles (93 %) to the total concentration measured on NPF event days within a volcanic plume. In a next step, particular attention was paid to the concentration of particles with dp>50 nm (N50), used as a proxy for potential CCN population. The contribution of secondary particles to the increase in N50 was the most frequent in plume conditions, and the magnitude of the increase was also more important on plume days compared to non-plume days. Finally, in order to further evaluate the effect of volcanic plume conditions on the occurrence of NPF, we analysed the variations of the condensation sink (CS) and [H2SO4], previously reported to play a key role in the process. Over the investigated months, higher CS (calculated prior to nucleation hours) were observed in plume conditions and coincided with high SO2 mixing ratios. Those most likely compensated for the strengthened loss rate of the vapours and favoured the occurrence of NPF, suggesting at the same time a key role of H2SO4 in the process. This last hypothesis was further supported by the correlation between the formation rate of 2 nm particles (J2) and [H2SO4], and by the fair approximation of J2 that was obtained by means of a recent parameterization of the binary nucleation of H2SO4–H2O. This last result demonstrates that in the absence of direct measurements of [H2SO4] and sub-3 nm particle concentrations, estimates of J2 could be fairly estimated from the knowledge of SO2 mixing ratios only. Finally, the use of the parameterization for ion-induced binary nucleation also highlighted the likely significant contribution of ion-induced nucleation for [H2SO4] below ∼8×108 cm−3.
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Pistone, Kristina, Paquita Zuidema, Robert Wood, Michael Diamond, Arlindo M. da Silva, Gonzalo Ferrada, Pablo E. Saide, et al. "Exploring the elevated water vapor signal associated with the free tropospheric biomass burning plume over the southeast Atlantic Ocean." Atmospheric Chemistry and Physics 21, no. 12 (June 29, 2021): 9643–68. http://dx.doi.org/10.5194/acp-21-9643-2021.
Abstract:
Abstract. In southern Africa, widespread agricultural fires produce substantial biomass burning (BB) emissions over the region. The seasonal smoke plumes associated with these emissions are then advected westward over the persistent stratocumulus cloud deck in the southeast Atlantic (SEA) Ocean, resulting in aerosol effects which vary with time and location. Much work has focused on the effects of these aerosol plumes, but previous studies have also described an elevated free tropospheric water vapor signal over the SEA. Water vapor influences climate in its own right, and it is especially important to consider atmospheric water vapor when quantifying aerosol–cloud interactions and aerosol radiative effects. Here we present airborne observations made during the NASA ORACLES (ObseRvations of Aerosols above CLouds and their intEractionS) campaign over the SEA Ocean. In observations collected from multiple independent instruments on the NASA P-3 aircraft (from near-surface to 6–7 km), we observe a strongly linear correlation between pollution indicators (carbon monoxide (CO) and aerosol loading) and atmospheric water vapor content, seen at all altitudes above the boundary layer. The focus of the current study is on the especially strong correlation observed during the ORACLES-2016 deployment (out of Walvis Bay, Namibia), but a similar relationship is also observed in the August 2017 and October 2018 ORACLES deployments. Using reanalyses from the European Centre for Medium-Range Weather Forecasts (ECMWF) and Modern-Era Retrospective analysis for Research and Applications, Version 2 (MERRA-2), and specialized WRF-Chem simulations, we trace the plume–vapor relationship to an initial humid, smoky continental source region, where it mixes with clean, dry upper tropospheric air and then is subjected to conditions of strong westward advection, namely the southern African easterly jet (AEJ-S). Our analysis indicates that air masses likely left the continent with the same relationship between water vapor and carbon monoxide as was observed by aircraft. This linear relationship developed over the continent due to daytime convection within a deep continental boundary layer (up to ∼5–6 km) and mixing with higher-altitude air, which resulted in fairly consistent vertical gradients in CO and water vapor, decreasing with altitude and varying in time, but this water vapor does not originate as a product of the BB combustion itself. Due to a combination of conditions and mixing between the smoky, moist continental boundary layer and the dry and fairly clean upper-troposphere air above (∼6 km), the smoky, humid air is transported by strong zonal winds and then advected over the SEA (to the ORACLES flight region) following largely isentropic trajectories. Hybrid Single-Particle Lagrangian Integrated Trajectory model (HYSPLIT) back trajectories support this interpretation. This work thus gives insights into the conditions and processes which cause water vapor to covary with plume strength. Better understanding of this relationship, including how it varies spatially and temporally, is important to accurately quantify direct, semi-direct, and indirect aerosol effects over this region.
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Liu, W. T., C. L. Chu, and T. Zhou. "Thymol and Acetic Acid Vapors Reduce Postharvest Brown Rot of Apricots and Plums." HortScience 37, no. 1 (February 2002): 151–56. http://dx.doi.org/10.21273/hortsci.37.1.151.
Abstract:
Fumigation with 1 mg·L-1 of thymol vapor retarded mycelial growth of Monilinia fructicola (G. Wint.) Honey. Mean colony diameter was reduced from 49 mm in the control to 13 mm when the conidia were cultured on potato dextrose agar. Fumigation of apricots (Prunus armeniaca L.) with 2 mg·L-1 of thymol vapor reduced the germination of M. fructicola conidia to 2% compared with 98% on untreated fruit. Microscopic observations showed that the spores fumigated with thymol were shrunken and had collapsed protoplasts. In in vivo experiments, surface-sterilized apricots and plums (Prunus salicina L.) were inoculated with conidia of M. fructicola by applying 20 μL of a spore suspension to wounds on the fruit, and then were fumigated with thymol or acetic acid. The incidence of brown rot was reduced to 3% and 32% when `Manch' apricots were fumigated with thymol or acetic acid at 5 mg·L-1, respectively, compared with 64% incidence in untreated fruit. Fumigation of `Violette' plums with thymol or acetic acid at 8 mg·L-1 reduced brown rot from 88% in the control to 24% and 25%, respectively. Fumigation of `Veeblue' plums with thymol at 4 mg·L-1 reduced brown rot from 56% in the control to 14%. Fumigation of apricots with thymol resulted in firmer fruit and higher surface browning, but total soluble solids and titratable acidity were not affected. Fumigation of plum with thymol resulted in higher total soluble solids, but firmness and titratable acidity were not affected. Thymol fumigation caused phytotoxicity on apricots but not on plums.
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Fifer, Lucas M., David C. Catling, and Jonathan D. Toner. "Chemical Fractionation Modeling of Plumes Indicates a Gas-rich, Moderately Alkaline Enceladus Ocean." Planetary Science Journal 3, no. 8 (August 1, 2022): 191. http://dx.doi.org/10.3847/psj/ac7a9f.
Abstract:
Abstract Enceladus harbors an ocean beneath its ice crust that erupts spectacular plumes from fissures at the south pole. The plume composition was measured by the Cassini spacecraft, and provides evidence for the ocean’s gas content, salinity, pH, and potential for life. Understanding the ocean’s composition is complicated by physicochemical processes that alter the plume composition during eruption, such as water vapor condensation in the icy fissures and gas exsolution from the ocean surface. We developed a model that includes key fractionation processes, in particular fractionation during gas exsolution, which has not been previously considered. Our model predicts a moderately alkaline (pH 7.95–9.05), gas-rich ocean (∼10−5–10−3 molal) with high concentrations of ammonium ions (10−2–10−1 molal). Our derived dissolved gas concentrations are higher than in recent studies because we account for gas exsolution, which depletes gases in the plume compared to the ocean, and because our model conserves mass flow rates between gas exsolution from the ocean and eruption from the tiger stripe fissures. We find carbon dioxide and hydrogen concentrations that could provide sufficient chemical energy for oceanic life in the form of hydrogenotrophic methanogens. Carbon dioxide concentrations of 10−5–10−3 molal indicate a more Earth-like pH than the pH ∼8.5–13.5 in previous studies. The inferred bulk ammonium and total inorganic carbon concentrations are consistent with cometary levels. This corroborates evidence from cometary deuterium-hydrogen (D/H) ratios that Enceladus formed from comet-like planetesimals. Our results suggest a gas-rich ocean that inherited its high volatile concentrations from comet-like building blocks.
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Bredemeyer, Stefan, Franz-Georg Ulmer, Thor Hansteen, and Thomas Walter. "Radar Path Delay Effects in Volcanic Gas Plumes: The Case of Láscar Volcano, Northern Chile." Remote Sensing 10, no. 10 (September 21, 2018): 1514. http://dx.doi.org/10.3390/rs10101514.
Abstract:
Modern volcano monitoring commonly involves Interferometric Synthetic Aperture Radar (InSAR) measurements to identify ground motions caused by volcanic activity. However, InSAR is largely affected by changes in atmospheric refractivity, in particular by changes which can be attributed to the distribution of water (H2O) vapor in the atmospheric column. Gas emissions from continuously degassing volcanoes contain abundant water vapor and thus produce variations in the atmospheric water vapor content above and downwind of the volcano, which are notably well captured by short-wavelength X-band SAR systems. These variations may in turn cause differential phase errors in volcano deformation estimates due to excess radar path delay effects within the volcanic gas plume. Inversely, if these radar path delay effects are better understood, they may be even used for monitoring degassing activity, by means of the precipitable water vapor (PWV) content in the plume at the time of SAR acquisitions, which may provide essential information on gas plume dispersion and the state of volcanic and hydrothermal activity. In this work we investigate the radar path delays that were generated by water vapor contained in the volcanic gas plume of the persistently degassing Láscar volcano, which is located in the dry Atacama Desert of Northern Chile. We estimate water vapor contents based on sulfur dioxide (SO2) emission measurements from a scanning UV spectrometer (Mini-DOAS) station installed at Láscar volcano, which were scaled by H2O/SO2 molar mixing ratios obtained during a multi-component Gas Analyzer System (Multi-GAS) survey on the crater rim of the volcano. To calculate the water vapor content in the downwind portion of the plume, where an increase of water vapor is expected, we further applied a correction involving estimation of potential evaporation rates of water droplets governed by turbulent mixing of the condensed volcanic plume with the dry atmosphere. Based on these estimates we obtain daily average PWV contents inside the volcanic gas plume of 0.2–2.5 mm equivalent water column, which translates to a slant wet delay (SWD) in DInSAR data of 1.6–20 mm. We used these estimates in combination with our high resolution TerraSAR-X DInSAR observations at Láscar volcano, in order to demonstrate the occurrence of repeated atmospheric delay patterns that were generated by volcanic gas emissions. We show that gas plume related refractivity changes are significant and detectable in DInSAR measurements. Implications are two-fold: X-band satellite radar observations also contain information on the degassing state of a volcano, while deformation signals need to be interpreted with care, which has relevance for volcano observations at Láscar and for other sites worldwide.
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Yin Jie, 殷杰, 郝亮 Hao Liang, 杨亮亮 Yang Liangliang, 李妍 Li Yan, 李正 Li Zheng, 孙庆磊 Sun Qinglei, and 石斌 Shi Bin. "激光选区熔化增材制造中金属蒸气与飞溅相互作用研究." Chinese Journal of Lasers 49, no. 14 (2022): 1402202. http://dx.doi.org/10.3788/cjl202249.1402202.
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Pumphrey, Hugh C., Michael J. Schwartz, Michelle L. Santee, George P. Kablick III, Michael D. Fromm, and Nathaniel J. Livesey. "Microwave Limb Sounder (MLS) observations of biomass burning products in the stratosphere from Canadian forest fires in August 2017." Atmospheric Chemistry and Physics 21, no. 22 (November 15, 2021): 16645–59. http://dx.doi.org/10.5194/acp-21-16645-2021.
Abstract:
Abstract. Forest fires in British Columbia in August 2017 caused a pyrocumulonimbus event that injected a polluted air mass into the lower stratosphere. The Microwave Limb Sounder (MLS) on the Aura satellite first observed the polluted air mass on 14 August 2017 and continued to observe it for 60 d (100 d in water vapour). We estimate the mass of CO injected into the stratosphere to be 2400 Gg. Events in which a fire injects its burning products directly into the stratosphere are rare: this is the third of four such events in the 16 years since the launch of Aura, the second largest of the four events, and the only one in the Northern Hemisphere. The other three events occurred in Australia in December 2006, February 2009 and from December 2019 to January 2020. Unlike the 2006 and 2009 events, but like the 2019–2020 event, the polluted air mass described here had a clearly elevated water vapour content: between 2.5 and 5 times greater than that in the surrounding atmosphere. We describe the evolution of the polluted air mass, showing that it rose to an altitude of about 24 km (31 hPa) and divided into several identifiable parts. In addition to CO and H2O, we observe enhanced amounts of HCN, CH3CN, CH3Cl and CH3OH with mixing ratios in the range to be expected from a variety of measurements in other biomass burning plumes. We use back trajectories and plume-dispersion modelling to demonstrate that the pollutants observed by MLS originated in the British Columbia fires, the likeliest source being at 53.2∘ N, 121.8∘ W at 05:20 UTC on 13 August 2017.
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Roger, Javier, Luis Guanter, Javier Gorroño, and Itziar Irakulis-Loitxate. "Exploiting the entire near-infrared spectral range to improve the detection of methane plumes with high-resolution imaging spectrometers." Atmospheric Measurement Techniques 17, no. 4 (February 26, 2024): 1333–46. http://dx.doi.org/10.5194/amt-17-1333-2024.
Abstract:
Abstract. Remote sensing emerges as an important tool for the detection of methane plumes emitted by so-called point sources, which are common in the energy sector (e.g., oil and gas extraction and coal mining activities). In particular, satellite imaging spectroscopy missions covering the shortwave infrared part of the solar spectrum are very effective for this application. These instruments sample the methane absorption features at the spectral regions around 1700 and 2300 nm, which enables the retrieval of methane concentration enhancements per pixel. Data-driven retrieval methods, in particular those based on the matched filter concept, are widely used to produce maps of methane concentration enhancements from imaging spectroscopy data. Using these maps enables the detection of plumes and the subsequent identification of active sources. However, retrieval artifacts caused by particular surface components may sometimes appear as false plumes or disturbing elements in the methane maps, which complicates the identification of real plumes. In this work, we use a matched filter that exploits a wide spectral window (1000–2500 nm) instead of the usual 2100–2450 nm window with the aim of reducing the occurrence of retrieval artifacts and background noise. This enables a greater ability to discriminate between surface elements and methane. The improvement in plume detection is evaluated through an analysis derived from both simulated data and real data from areas including active point sources, such as the oil and gas (O&G) industry from San Joaquin Valley (US) and the coal mines from the Shanxi region (China). We use datasets from the Precursore IperSpettrale della Missione Applicativa (PRISMA) and the Environmental Mapping and Analysis Program (EnMAP) satellite imaging spectrometer missions and from the Airborne Visible/Infrared Imaging Spectrometer – Next Generation (AVIRIS-NG) instrument. We find that the interference with atmospheric carbon dioxide and water vapor is generally almost negligible, while co-emission or overlapping of these trace gases with methane plumes leads to a reduction in the retrieved concentration values. Attenuation will also occur in the case of methane emissions situated above surface structures that are associated with retrieval artifacts. The results show that the new approach is an optimal trade-off between the reduction in background noise and retrieval artifacts. This is illustrated by a comprehensive analysis in a PRISMA dataset with 15 identified plumes, where the output mask from an automatic detection algorithm shows an important reduction in the number of clusters not related to CH4 emissions.
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Legras, Bernard, Clair Duchamp, Pasquale Sellitto, Aurélien Podglajen, Elisa Carboni, Richard Siddans, Jens-Uwe Grooß, Sergey Khaykin, and Felix Ploeger. "The evolution and dynamics of the Hunga Tonga–Hunga Ha'apai sulfate aerosol plume in the stratosphere." Atmospheric Chemistry and Physics 22, no. 22 (November 23, 2022): 14957–70. http://dx.doi.org/10.5194/acp-22-14957-2022.
Abstract:
Abstract. We use a combination of spaceborne instruments to study the unprecedented stratospheric plume after the Tonga eruption of 15 January 2022. The aerosol plume was initially formed of two clouds at 30 and 28 km, mostly composed of submicron-sized sulfate particles, without ash, which is washed out within the first day following the eruption. The large amount of injected water vapour led to a fast conversion of SO2 to sulfate aerosols and induced a descent of the plume to 24–26 km over the first 3 weeks by radiative cooling. Whereas SO2 returned to background levels by the end of January, volcanic sulfates and water still persisted after 6 months, mainly confined between 35∘ S and 20∘ N until June due to the zonal symmetry of the summer stratospheric circulation at 22–26 km. Sulfate particles, undergoing hygroscopic growth and coagulation, sediment and gradually separate from the moisture anomaly entrained in the ascending branch Brewer–Dobson circulation. Sulfate aerosol optical depths derived from the IASI (Infrared Atmospheric Sounding Interferometer) infrared sounder show that during the first 2 months, the aerosol plume was not simply diluted and dispersed passively but rather organized in concentrated patches. Space-borne lidar winds suggest that those structures, generated by shear-induced instabilities, are associated with vorticity anomalies that may have enhanced the duration and impact of the plume.
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Liu, Jiaqi, Bin Wei, Hongjie Chang, Jie Li, and Guang Yang. "Review of Visual Measurement Methods for Metal Vaporization Processes in Laser Powder Bed Fusion." Micromachines 14, no. 7 (June 30, 2023): 1351. http://dx.doi.org/10.3390/mi14071351.
Abstract:
Laser powder bed fusion (LPBF) is of great importance for the visual measurement and analysis of the metallization process, which is the process of solid, liquid, and gas phase transformations of metal powders under high-energy laser irradiation due to the low boiling point/high saturated vapor pressure. Since the evaporation of metals involves the interaction of driving forces such as vapor back pressure, surface tension, and gravity, the movement of the melt pool is not stable. At the same time, it also produces vaporization products such as vapor plumes and sprays, which cause defects such as bubbles, porosity, lack of fusion, inclusions, etc., during the manufacturing process of the parts, affecting the performance and manufacturing quality of the parts. More and more researchers are using imaging technologies, such as high-speed X-ray, high-speed visible light cameras, and high-speed schlieren imaging, to perform noncontact visual measurements and analyses of the melt pool, vapor plume, and spatter during the metal evaporation process, and the results show that the metal evaporation process can be suppressed by optimizing the process parameters and changing the processing atmosphere, thereby reducing part defects and improving part performance and built part quality. This paper reviews the research on metal evaporation mechanisms and visual measurement methods of metal evaporation, then discusses the measures of metal evaporation, and finally summarizes and prospects the future research hotspots of LPBF technology, according to the existing scholars’ research on numerical simulation analysis and visual measurement methods of the metal evaporation process.
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Fiedler, V., F. Arnold, H. Schlager, A. Dörnbrack, L. Pirjola, and A. Stohl. "East Asian SO<sub>2</sub> pollution plume over Europe – Part 2: Evolution and potential impact." Atmospheric Chemistry and Physics 9, no. 14 (July 20, 2009): 4729–45. http://dx.doi.org/10.5194/acp-9-4729-2009.
Abstract:
Abstract. We report on the first observation-based case study of an aged East Asian anthropogenic SO2 pollution plume over Europe. Our airborne measurements in that plume detected highly elevated SO2 mole fractions (up to 900 pmol/mol) between about 5000 and 7000 m altitude. Here, we focus on investigations of the origin, dispersion, evolution, conversion, and potential impact of the observed excess SO2. In particular, we investigate SO2 conversion to gas-phase sulfuric acid and sulfuric acid aerosols. Our FLEXPART and LAGRANTO model simulations, along with additional trace gas measurements, suggest that the plume originated from East Asian fossil fuel combustion sources and, 8–7 days prior to its arrival over Europe, ascended over the coast region of central East Asia to 9000 m altitude, probably in a cyclonic system with an associated warm conveyor belt. During this initial plume ascent a substantial fraction of the initially available SO2 must have escaped from removal by cloud processes. Hereafter, while mostly descending slowly, the plume experienced advection across the North Pacific, North America and the North Atlantic. During its upper troposphere travel, clouds were absent in and above the plume and OH-induced gas-phase conversion of SO2 to gas-phase sulfuric acid (GSA) was operative, followed by GSA nucleation and condensation leading to sulfuric acid aerosol formation and growth. Our AEROFOR model simulations indicate that numerous large sulfuric acid aerosol particles were formed, which at least temporarily, caused substantial horizontal visibility degradation, and which have the potential to act as water vapor condensation nuclei in liquid water cloud formation, already at water vapor supersaturations as low as about 0.1%. Our AEROFOR model simulations also indicate that those fossil fuel combustion generated soot particles, which have survived cloud induced removal during the initial plume ascent, have experienced extensive H2SO4/H2O-coating, during upper troposphere plume travel. This coating may have dramatically altered the morphology and markedly increased the light absorption efficiency of soot particles.
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Jiménez-Rodríguez, César Dionisio, Miriam Coenders-Gerrits, Bart Schilperoort, Adriana del Pilar González-Angarita, and Hubert Savenije. "Vapor plumes in a tropical wet forest: spotting the invisible evaporation." Hydrology and Earth System Sciences 25, no. 2 (February 11, 2021): 619–35. http://dx.doi.org/10.5194/hess-25-619-2021.
Abstract:
Abstract. Forest evaporation exports a vast amount of water vapor from land ecosystems into the atmosphere. Meanwhile, evaporation during rain events is neglected or considered of minor importance in dense ecosystems. Air convection moves the water vapor upwards leading to the formation of large invisible vapor plumes, while the identification of visible vapor plumes has not yet been studied. This work describes the formation process of vapor plumes in a tropical wet forest as evidence of evaporation processes happening during rain events. In the dry season of 2018 at La Selva Biological Station (LSBS) in Costa Rica it was possible to spot visible vapor plumes within the forest canopy. The combination of time-lapse videos at the canopy top with conventional meteorological measurements along the canopy profile allowed us to identify the driver conditions required for this process to happen. This phenomenon happened only during rain events. Visible vapor plumes during the daytime occurred when the following three conditions are accomplished: presence of precipitation (P), air convection, and a lifting condensation level value smaller than 100 m at 43 m height (zlcl.43).
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Wen, Qian, and Xiang Dong Gao. "Analysis of Image Characteristics of Plume and Spatter of High Power Disk Laser Welding Based on K-L Transform." Advanced Materials Research 532-533 (June 2012): 330–34. http://dx.doi.org/10.4028/www.scientific.net/amr.532-533.330.
Abstract:
Metal vapor plume and spatters are the important phenomena in the process of high power disk laser welding, and there exists a close relationship with the welding stability. The images of metal vapor plume and spatters which captured by a high speed camera during high power disk laser welding were analyzed in this experiment. Image processing techniques such as median filtering, Wiener filtering, gray level threshold and lightness transform were used to process the images so that the image characteristic parameters such as the area and number of spatters in an image, the average gray, mean value, variance and entropy of a spatter gray level image and the coordinate ratio of the centriod of plume and the welding point can be extracted. To reflect the actual welding results obviously by those characteristic parameters, K-L transform method was used to get a new set of characteristic parameters. Experimental results showed that this new set of characteristic parameters could reflect the actual welding effectively.
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Immler, F., D. Engelbart, and O. Schrems. "Fluorescence from atmospheric aerosol detected by a lidar indicates biogenic particles in the lowermost stratosphere." Atmospheric Chemistry and Physics 5, no. 2 (February 8, 2005): 345–55. http://dx.doi.org/10.5194/acp-5-345-2005.
Abstract:
Abstract. With a lidar system that was installed in Lindenberg/Germany, we observed in June 2003 an extended aerosol layer at 13km altitude in the lowermost stratosphere. This layer created an inelastic backscatter signal that we detected with a water vapour Raman channel, but that was not produced by Raman scattering. Also, we find evidence for inelastic scattering from a smoke plume from a forest fire that we observed in the troposphere. We interpret the unexpected properties of these aerosols as fluorescence induced by the laser beam at organic components of the aerosol particles. Fluorescence from ambient aerosol had not yet been considered detectable by lidar systems. However, organic compounds such as polycyclic aromatic hydrocarbons sticking to the aerosol particles, or bioaerosol such as bacteria, spores or pollen fluoresce when excited with UV-radiation in a way that is detectable by our lidar system. Therefore, we conclude that fluorescence from organic material released by biomass burning creates, inelastic backscatter signals that we measured with our instrument and thus demonstrate a new and powerful way to characterize aerosols by a remote sensing technique. The stratospheric aerosol layer that we have observed in Lindenberg for three consecutive days is likely to be a remnant from Siberian forest fire plumes lifted across the tropopause and transported around the globe.
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Podrabinnik, Pavel A., Alexander E. Shtanko, Roman S. Khmyrov, Andrey D. Korotkov, and Andrey V. Gusarov. "Interferometry of Gas-Phase Flows during Selective Laser Melting." Applied Sciences 10, no. 1 (December 27, 2019): 231. http://dx.doi.org/10.3390/app10010231.
Abstract:
Gas-phase flows occurring in a plume in a processing zone during selective laser melting (SLM) can significantly affect the quality of the process. To further enhance SLM performance, the characteristics of the flows should be considered. In this article, the vapor-gas jet emerging from the laser processing zone was studied. It was visualized by interferometry to evaluate flow velocity, geometry and changes in refractory index depending on laser power. The velocity and pressure fields of the vapor jet and the entrained ambient gas were estimated by mathematical modeling. It was shown that the increase of laser power led to higher jet velocity and greater change in its refractory index. The latter also was used to evaluate the content of metal vapor in the plume and its influence on the absorption of laser radiation.
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Hansen, C. J., L. W. Esposito, A. I. F. Stewart, B. Meinke, B. Wallis, J. E. Colwell, A. R. Hendrix, K. Larsen, W. Pryor, and F. Tian. "Water vapour jets inside the plume of gas leaving Enceladus." Nature 456, no. 7221 (November 2008): 477–79. http://dx.doi.org/10.1038/nature07542.
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Brock, C., R. Hohenstein, and M. Schmidt. "Mechanisms of vapour plume formation in laser deep penetration welding." Optics and Lasers in Engineering 58 (July 2014): 93–101. http://dx.doi.org/10.1016/j.optlaseng.2014.02.001.
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Kleinknecht, Simon Matthias, Holger Class, and Jürgen Braun. "Experimental study on retardation of a heavy NAPL vapor in partially saturated porous media." Hydrology and Earth System Sciences 21, no. 3 (March 8, 2017): 1381–96. http://dx.doi.org/10.5194/hess-21-1381-2017.
Abstract:
Abstract. Non-aqueous-phase liquid (NAPL) contaminants introduced into the unsaturated zone spread as a liquid phase; however, they can also vaporize and migrate in a gaseous state. Vapor plumes migrate easily and thus pose a potential threat to underlying aquifers. Large-scale column experiments were performed to quantify partitioning processes responsible for the retardation of carbon disulfide (CS2) vapor in partially saturated porous media. The results were compared with a theoretical approach taking into account the partitioning into the aqueous phase as well as adsorption to the solid matrix and to the air–water interface. The experiments were conducted in large, vertical columns (i.d. of 0.109 m) of 2 m length packed with different porous media. A slug of CS2 vapor and the conservative tracer argon was injected at the bottom of the column followed by a nitrogen chase. Different seepage velocities were applied to characterize the transport and to evaluate their impact on retardation. Concentrations of CS2 and argon were measured at the top outlet of the column using two gas chromatographs. The temporal-moment analysis for step input was employed to evaluate concentration breakthrough curves and to quantify dispersion and retardation. The experiments conducted showed a pronounced retardation of CS2 in moist porous media which increased with water saturation. The comparison with an analytical solution helped to identify the relative contributions of partitioning processes to retardation. Thus, the experiments demonstrated that migrating CS2 vapor is retarded as a result of partitioning processes. Moreover, CS2 dissolved in the bulk water is amenable to biodegradation. The first evidence of CS2 decay by biodegradation was found in the experiments. The findings contribute to the understanding of vapor-plume transport in the unsaturated zone and provide valuable experimental data for the transfer to field-like conditions.
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Mihai, Sabin, Diana Chioibasu, Muhammad Arif Mahmood, Liviu Duta, Marc Leparoux, and Andrei C. Popescu. "Real-Time Defects Analyses Using High-Speed Imaging during Aluminum Magnesium Alloy Laser Welding." Metals 11, no. 11 (November 22, 2021): 1877. http://dx.doi.org/10.3390/met11111877.
Abstract:
In this study a continuous wave Ytterbium-doped Yttrium Aluminum Garnet (Yb: YAG) disk laser has been used for welding of AlMg3 casted alloy. A high-speed imaging camera has been employed to record hot vapor plume features during the process. The purpose was to identify a mechanism of pores detection in real-time based on correlations between metallographic analyses and area/intensity of the hot vapor in various locations of the samples. The pores formation and especially the position of these pores had to be kept under control in order to weld thick samples. Based on the characterization of the hot vapor, it has been found that the increase of the vapor area that exceeded a threshold value (18.5 ± 1 mm2) was a sign of pores formation within the weld seam. For identification of the pores’ locations during welding, the monitored element was the hot vapor intensity. The hot vapor core spots having a grayscale level reaching 255 was associated with the formation of a local pore. These findings have been devised based on correlation between pores placement in welds cross-section microscopy images and the hot vapor plume features in those respective positions.
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Thareja, Raj K., A. Mohanta, D. Yadav, and A. Kushwaha. "Synthesis and Characterization of Nanoparticles and Nanocrystalline Functional Films." Materials Science Forum 636-637 (January 2010): 709–13. http://dx.doi.org/10.4028/www.scientific.net/msf.636-637.709.
Abstract:
This work reports on spectroscopic investigations of interaction of an expanding laser ablated plume of aluminum, zinc, graphite with ambient atmosphere of oxygen and nitrogen gas and the formation of nitrides and oxides. The ambient pressure and fluence dependence on the reactive process occurring in the ablated plume responsible for formation of oxides and nitrides is discussed. Fast photography/imaging technique using intensified charge coupled device (ICCD) is gaining importance as a diagnostic tool for understanding the dynamics of the expanding plasma plume and the gas phase nanoparticle synthesis, thus providing a novel way to understand the transportation of nanoparticles and of control of particle size. Two dimensional images of the expanding plasma plume were captured using ICCD to understand the role of vapor and shock temperature. A comprehensive study done on oxide and nitrides films using pulsed laser deposition technique for possible laser oscillations in UV region of electromagnetic spectrum is presented.
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Lee, Alex K. Y., Max G. Adam, John Liggio, Shao-Meng Li, Kun Li, Megan D. Willis, Jonathan P. D. Abbatt, et al. "A large contribution of anthropogenic organo-nitrates to secondary organic aerosol in the Alberta oil sands." Atmospheric Chemistry and Physics 19, no. 19 (October 2, 2019): 12209–19. http://dx.doi.org/10.5194/acp-19-12209-2019.
Abstract:
Abstract. The oil sands industry in Alberta, Canada, represents a large anthropogenic source of secondary organic aerosol (SOA). Atmospheric emissions from oil sands operations are a complex mixture of gaseous and particulate pollutants. Their interaction can affect the formation and characteristics of SOA during plume dispersion, but their chemical evolution remains poorly understood. Oxidative processing of organic vapours in the presence of NOx can lead to particulate organo-nitrate (pON) formation, with important impacts on the SOA budgets, the nitrogen cycle and human health. We provide the first direct field evidence, from ground- and aircraft-based real-time aerosol mass spectrometry, that anthropogenic pON contributed up to half of SOA mass that was freshly produced within the emission plumes of oil sands facilities. Using a top-down emission-rate retrieval algorithm constrained by aircraft measurements, we estimate the production rate of pON in the oil sands region to be ∼15.5 t d−1. We demonstrate that pON formation occurs via photo-oxidation of intermediate-volatility organic compounds (IVOCs) in high-NOx environments, providing observational constraints to improve current SOA modelling frameworks. Our ambient observations are supported by laboratory photo-oxidation experiments of IVOCs from bitumen vapours under high-NOx conditions, which demonstrate that pON can account for 30 %–55 % of the observed SOA mass depending on the degree of photochemical ageing. The large contribution of pON to freshly formed anthropogenic SOA illustrates the central role of pON in SOA production from the oil and gas industry, with relevance for other urban and industrial regions with significant anthropogenic IVOC and NOx emissions.
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Sharma, H., M. M. Hedman, and S. Vahidinia. "New Insights into Variations in Enceladus Plume Particle Launch Velocities from Cassini-VIMS Spectral Data." Planetary Science Journal 4, no. 6 (June 1, 2023): 108. http://dx.doi.org/10.3847/psj/acd5d4.
Abstract:
Abstract Enceladus’s plume consists mainly of a mixture of water vapor and solid ice particles that may originate from a subsurface ocean. The physical processes underlying Enceladus’s plume particle dynamics are still being debated, and quantifying the particles’ size distribution and launch velocities can help constrain these processes. Cassini’s Visual and Infrared Mapping Spectrometer observed the Enceladus plume over a wavelength range of 0.9–5.0 μm for a significant fraction of Enceladus’s orbital period on three dates in the summer of 2017. We find that the relative brightness of the plume on these different dates varies with wavelength, implying that the particle size distribution in the plume changes over time. These observations also enable us to study how the particles’ launch velocities vary with time and observed wavelength. We find that the typical launch velocity of particles remains between 140 and 148 m s−1 at wavelengths between 1.2 and 3.7 μm. This may not be consistent with prior models where particles are only accelerated by interactions with the vent walls and gas and could imply that mutual particle collisions close to the vent are more important than previously recognized.