From February to September 2012 routine daily backscatter Lidar measurements were performed in Concepcion, a major city located in central Chile (36 degrees 47' S, 73 degrees 7' W, 12 amsl), providing the firs...
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From February to September 2012 routine daily backscatter Lidar measurements were performed in Concepcion, a major city located in central Chile (36 degrees 47' S, 73 degrees 7' W, 12 amsl), providing the first regular measurements of tropospheric aerosol backscatter profiles in the country. The Lidar system, the first of its kind in Chile, has been developed locally to study the evolution of the atmospheric boundary layer (ABL) and vertical profiles of optical properties of lower and local tropospheric aerosols. This work presents the first results on aerosol optical properties retrieved for a Chilean coastal city, and it provides, for the first time, valuable long-term information about air pollution in the country, revealing seasonal variations of aerosol backscattering and extinction coefficients. In addition to determination of low content of tropospheric aerosols for this city, the elastic Lidar system was used to identify intrusions of external aerosol layers through significant increment of aerosol optical properties along the lower heights of local troposphere. (C) 2015 Elsevier Ltd. All rights reserved.
Two laser-induced breakdown spectroscopy (LIBS) systems (soil LIBS and aerosol LIBS) were used to determine the elemental composition of soils and ambient aerosols less than 2.5 mu m in Ny-Alesund, Svalbard (the world...
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Two laser-induced breakdown spectroscopy (LIBS) systems (soil LIBS and aerosol LIBS) were used to determine the elemental composition of soils and ambient aerosols less than 2.5 mu m in Ny-Alesund, Svalbard (the world's most northerly human settlement). For soil LIBS measurements, matrix effects such as moisture content, soil grain size, and surrounding gas on the LIBS response were minimized. When Ar gas was supplied onto the soil sample surfaces, a significant enhancement in LIBS emission lines was observed. Arctic soil samples were collected at 10 locations, and various elements (Al, Ba, C, Ca, Cu, Fe, H, K, Mg, Mn, N, Na, O, Pb, and Si) were detected in soils. The elemental distribution in arctic soils was clearly distinguishable from those in urban and abandoned mining soils in Korea. Moreover, the concentrations of most of anthropogenic metals were fairly low, and localized sources in extremely close proximity affected the elevated level of Cu in the soil samples derived from Ny-Alesund. The number of elements detected in aerosols (C, Ca, H, K, Mg, Na, and 0) was lower than those determined in soils. The elements in aerosols can mainly originate from minerals and sea salts. The elemental distribution in aerosols was also clearly distinguishable from that in soils, suggesting that the resuspension of local soil particles by wind erosion into aerosols was minimal. The daily variation of particle number concentration (RSD = 71%) and the elements in aerosols (RSD = 25%) varied substantially, possibly due to fluctuating air masses and meteorological conditions. (C) 2017 Elsevier B.V. All rights reserved.
Spherical particles of silica or tantalum oxide were prepared by the hydrolysis of aerosols consisting of silicon tetrachloride or tantalum pentaethoxide, respectively, diluted in propanol-2. Silica particles so-obtai...
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Spherical particles of silica or tantalum oxide were prepared by the hydrolysis of aerosols consisting of silicon tetrachloride or tantalum pentaethoxide, respectively, diluted in propanol-2. Silica particles so-obtained were spherical but agglomerated, and of a rather broad size distribution. However, the particles of tantalum oxide prepared were spherical, non-agglomerated and of narrow size distribution; the mean diameter ranged between 0.84 and 1.72 μm, depending on temperature and the gas flow rate. In both cases the particles were amorphous and crystallized after calcination at high temperature.
The optical depolarizing properties of simulated stratospheric aerosols were studied in laboratory laser (0.633 microm) backscattering experiments for application to polarization lidar observations. Clouds composed of...
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The optical depolarizing properties of simulated stratospheric aerosols were studied in laboratory laser (0.633 microm) backscattering experiments for application to polarization lidar observations. Clouds composed of sulfuric acid solution droplets, some treated with ammonia gas, were observed during evaporation. The results indicate that the formation of minute ammonium sulfate particles from the evaporation of acid droplets produces linear depolarization ratios of delta approximately 0.02, but delta approximately 0.10-0.15 are generated from acid droplet crystallization effects associated with recycled aerosols and the introduction of ammonia gas into the chamber. It is concluded that partially crystallized sulfuric acid droplets are a likely candidate for explaining the lidar delta approximately 0.10 values that have been observed in the lower stratosphere in the absence of the relatively strong backscattering from homogeneous sulfuric acid droplet (delta approximately 0) or ice crystal (delta approximately 0.5) clouds.
The focus of present study is to quantify the radiation budget of aerosols over Jaipur (Northwestern, India) from 2011 to 2015. The Aerosol radiative forcing (ARF) has been determined for shortwave spectrum (0.3-3.0 m...
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The focus of present study is to quantify the radiation budget of aerosols over Jaipur (Northwestern, India) from 2011 to 2015. The Aerosol radiative forcing (ARF) has been determined for shortwave spectrum (0.3-3.0 mu m) individually for the top of the atmosphere (TOA), bottom of the atmosphere (BOA) and within the atmosphere (ATM) over study region. Santa Barbara DISORT Atmospheric Radiative Transfer model (SBDART) is used to simulate the aerosols radiative effect. The inter-annual monthly average of ARF at TOA during 2011-2015 is found between -11.40 to -5.60 W m(-2), while the ARF at BOA is found to be between -32.2 to -22.49 W m(-2). Likewise, the ARF within the atmosphere (ATM) comes between 14.04 to 22.47 W m(-2) over Jaipur. The SBDART model is run discretely for Dust period (DSP) and non-Dust Period (NDP) during the year 2012 to inspect the change in ARF during extreme events over the Jaipur site. During DSP, the net TOA and BOA forcing are found in the range -20.71 to -16.81 W m(-2) and -45.15 to -39.6 W m(-2), respectively, and net ATM forcing varies in the range 22.7 to 24.4 W m(-2). For the NDP, the corresponding value varies in the range -10.1 to -6.6 W m(-2) and -23.6 to -22.3 W m(-2). The net ATM forcing during NDP is between 12.2 to 17.05 W m(-2). The value of BOA increases more than similar to 67% during DSP than NDP. The more increase (-ve) in surface forcing represents the cooling of the surface during DSP. The results depict that dust over Jaipur in the vicinity of the Thar Desert is scattering in nature with high value (> 0.95) of SSA. The scattering is mostly high during summer and low in winter.
We present shipborne measurements of size-resolved concentrations of aerosol components across ocean waters next to the Antarctic Peninsula, South Orkney Islands, and South Georgia Island, evidencing aerosol features ...
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We present shipborne measurements of size-resolved concentrations of aerosol components across ocean waters next to the Antarctic Peninsula, South Orkney Islands, and South Georgia Island, evidencing aerosol features associated with distinct eco-regions. Nonmethanesulfonic acid Water-Soluble Organic Matter (WSOM) represented 6-8% and 11-22% of the aerosol PM1 mass originated in open ocean (OO) and sea ice (SI) regions, respectively. Other major components included sea salt (86-88% OO, 24-27% SI), non sea salt sulfate (3-4% OO, 35-40% SI), and MSA (1-2% OO, 11-12% SI). The chemical composition of WSOM encompasses secondary organic components with diverse behaviors: while alkylamine concentrations were higher in SI air masses, oxalic acid showed higher concentrations in the open ocean air. Our online single-particle mass spectrometry data exclude a widespread source from sea bird colonies, while the secondary production of oxalic acid and sulfur-containing organic species via cloud processing is suggested. We claim that the potential impact of the sympagic planktonic ecosystem on aerosol composition has been overlooked in past studies, and multiple eco-regions act as distinct aerosol sources around Antarctica.
aerosols play a crucial role in climate change by providing a radiation balance between the Earth and atmosphere. In the present study, aerosol sources and sinks have been identified over African region using the Mode...
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aerosols play a crucial role in climate change by providing a radiation balance between the Earth and atmosphere. In the present study, aerosol sources and sinks have been identified over African region using the Modern-Era Retrospective analysis for Research and Applications, Version 2 reanalysis data from 1985 to 2015. The study mainly focused on climatological and seasonal changes in aerosol distribution and concentrations over African continent and their impact on east African rainfall. Western Africa shows high concentrations of aerosol optical depth (AOD) of greater than 0.3 due to localized pressure changes and diverging winds from the Sahara desert. The highest amount of AOD (similar to 0.8) has been observed in winter season due to strong surface winds and high production of sea salt. When temperature is high in summer season (similar to 306 K), it has been observed that aerosol area distribution increases but their concentration decreases. The highest amount of rainfall (similar to 295 mm) was recorded in the winter season between 1997 and 1998. A strong inverse relationship was observed between aerosol and the east African rainfall. In 2015, the lowest amount of rainfall was observed in the summer season similar to 100 mm due to the observed high presence of aerosols. On average, the correlation coefficient between aerosols and precipitation over east Africa has been found to be negative. The increase in rainfall is associated with an increase in relative humidity. However, during the east African monsoon season, the presence of some aerosols cause the development of convective clouds and hence more rainfall.
The present study focuses on the simultaneous analysis of metallic species and radionuclide data from January 2009 to December 2011 in the dust deposited on filters in Malaga (Spain). Some metallic elements (Ca, Fe, K...
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The present study focuses on the simultaneous analysis of metallic species and radionuclide data from January 2009 to December 2011 in the dust deposited on filters in Malaga (Spain). Some metallic elements (Ca, Fe, K, Mg, Na, Zn, Pb, Cu, Ni) and radionuclides (Be-7 and(210)Pb) have been determined by inductively coupled plasma-mass spectroscopy and gamma spectrometry, respectively. For this analysis, daily variation of PM(10)mass concentration was additionally recorded at the nearest station belonging to the regional atmospheric pollution monitoring network. The comparison between(210)Pb, elemental lead, and PM(10)mass concentration reveals a different time variation for raining months, and an increase in the(210)Pb/Pb ratio indicates local sources of the particulate mass. Principal components analysis (PCA) applied to the datasets and calculation of enrichment factors relative to soil and seawater reveal that the atmospheric aerosol chemistry in this area of the Mediterranean is mostly influenced by crustal and marine sources rather than anthropogenic ones.
Iso-octane aerosols in air have been ignited with a focused Nd:YAG laser at pressures and temperatures of 100kPa and 270K and imaged using schlieren photography. The aerosol was generated using the Wilson cloud chambe...
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Iso-octane aerosols in air have been ignited with a focused Nd:YAG laser at pressures and temperatures of 100kPa and 270K and imaged using schlieren photography. The aerosol was generated using the Wilson cloud chamber technique. The droplet diameter, gas phase equivalence ratio and droplet number density were determined. The input laser energy and overall equivalence ratio were varied. For 270mJ pulse energies initial breakdown occurred at a number of sites along the laser beam axis. From measurements of the shock wave velocity it was found that energy was not deposited into the sites evenly. At pulse energies of 32mJ a single ignition site was observed. Overall fuel lean flames were observed to locally extinguish, however both stoichiometric and fuel rich flames were ignited. The minimum ignition energy was found to depend on the likelihood of a droplet existing at the focus of the laser beam.
The transfer of materials from the liquid phase to the gaseous phase by the bursting of gas bubbles at the liquid surface is of concern in many industrial and environmental applications, e.g., microorganism generation...
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The transfer of materials from the liquid phase to the gaseous phase by the bursting of gas bubbles at the liquid surface is of concern in many industrial and environmental applications, e.g., microorganism generation from wastewater treatment plants and health club whirlpools. Most previous studies have focused on single-bubble bursting, which is rarely found in actual situations. An experimental system has been developed that is large enough to accommodate multiple-bubble bursting and overcomes the difficulties of sampling and analysis of liquid droplets above the surface of a bubbling liquid. The system uses dynamic aerosol spectrometers to provide real-time information on the concentrations and size distributions of the liquid droplets generated and of the materials contained in the liquid droplets after their evaporation. Specially designed impactors are used to size classify the droplets so that the content of the droplets of various size ranges can be evaluated. Examples of measured droplet distributions show that the system is independent of the distance above the liquid surface at which the sample is taken. The geometric mean diameter of the droplets generated from 2.57-mm bubbles was found to be 2.0 μm with ag= 1.96. In one experiment with a suspension of 0.56-μm diameter latex spheres at a concentration of 109/cm3in distilled water, 61% of the measured droplets contained latex particles. This represented a several hundredfold enrichment over the bulk concentration of particles.
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