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Sample records for aerosol size analyzer

  1. Nanometer aerosol size analyzer (nASA) and data inversion

    NASA Astrophysics Data System (ADS)

    Han, Hee Siew

    A fast-response Nanometer Aerosol Size Analyzer (nASA) that is capable of scanning 30 size channels between 3 and 100 nm in a total time of 3 seconds was developed. The analyzer includes a bipolar charger (Po 210), an extended-length Nano DMA, and an electrometer. This combination of components provides particle size spectra at a scan rate of 0.1 second per channel free of uncertainties caused by response-time induced smearing. In addition, because of its thermodynamically stable means of particle detection, the nASA is useful for applications requiring measurements over a broad range of sample pressures and temperatures. Indeed, experimental transfer functions determined for the extended-length Nano-DMA using the Tandem Differential Mobility Analyzer technique indicate the nASA provides good size resolution at pressures as low as 200 Torr, corresponding to measurement at an altitude of 10 km. The second part of this study is devoted to the selection of an accurate data inversion algorithm. From the simulation results, it is found that MICRON provides the most stable solutions with good accuracy and reasonable convergent speed especially when aerosol distribution functions are bi-modal. All subsequent nASA measurement results are inverted using the MICRON algorithm. A second generation nASA was developed for the later series of engine exhaust measurements. Several improvements are implemented to the nASA to enhance its performance and ease of use. First, its physical size is reduced and the capability for controlling the DMA flow rates via computer software is added. The former improves the portability of the instrument and the latter allows the nASA to have an wider aerosol size ranges. Finally, the system was used in the EXperiment to Characterize Aircraft Volatile Aerosol and Trace species Emissions (EXCAVATE) workshop to investigate aerosol size distribution from a Boeing 757 engine. The results show that the aerosol size distributions from the engine are

  2. IN-SITU AERODYNAMIC SIZING OF AEROSOL PARTICLES WITH THE SPART ANALYZER

    EPA Science Inventory

    A single particle aerodynamic relaxation time (SPART) analyzer has been developed to measure the aerodynamic size distribution of aerosol particulates in the range 0.1 to 10.0 micrometer in diameter. The analyzer sizes and counts individual suspended particles and droplets from s...

  3. A Nanometer Aerosol Size Analyzer (nASA) for Rapid Measurement of High-Concentration Size Distributions

    NASA Technical Reports Server (NTRS)

    Han, Hee-Siew; Chen, Da-Ren; Pui, David Y. H.; Anderson, Bruce E.

    2001-01-01

    We have developed a fast-response Nanometer Aerosol Size Analyzer (nASA) that is capable of scanning 30 size channels between 3 and 100 nm in a total time of 3 seconds. The analyzer includes a bipolar charger (P0210), an extended-length Nanometer Differential Mobility Analyzer (Nano-DMA), and an electrometer (TSI 3068). This combination of components provides particle size spectra at a scan rate of 0.1 second per channel free of uncertainties caused by response-time-induced smearing. The nASA thus offers a fast response for aerosol size distribution measurements in high-concentration conditions and also eliminates the need for applying a de-smearing algorithm to resulting data. In addition, because of its thermodynamically stable means of particle detection, the nASA is useful for applications requiring measurements over a broad range of sample pressures and temperatures. Indeed, experimental transfer functions determined for the extended-length Nano-DMA using the Tandem Differential Mobility Analyzer (TDMA) technique indicate the nASA provides good size resolution at pressures as low as 200 Torr. Also, as was demonstrated in tests to characterize the soot emissions from the J85-GE engine of a T38 aircraft, the broad dynamic concentration range of the nASA makes it particularly suitable for studies of combustion or particle formation processes. Further details of the nASA performance as well as results from calibrations, laboratory tests and field applications are presented.

  4. Aerosol mobility size spectrometer

    DOEpatents

    Wang, Jian; Kulkarni, Pramod

    2007-11-20

    A device for measuring aerosol size distribution within a sample containing aerosol particles. The device generally includes a spectrometer housing defining an interior chamber and a camera for recording aerosol size streams exiting the chamber. The housing includes an inlet for introducing a flow medium into the chamber in a flow direction, an aerosol injection port adjacent the inlet for introducing a charged aerosol sample into the chamber, a separation section for applying an electric field to the aerosol sample across the flow direction and an outlet opposite the inlet. In the separation section, the aerosol sample becomes entrained in the flow medium and the aerosol particles within the aerosol sample are separated by size into a plurality of aerosol flow streams under the influence of the electric field. The camera is disposed adjacent the housing outlet for optically detecting a relative position of at least one aerosol flow stream exiting the outlet and for optically detecting the number of aerosol particles within the at least one aerosol flow stream.

  5. Real time infrared aerosol analyzer

    DOEpatents

    Johnson, Stanley A.; Reedy, Gerald T.; Kumar, Romesh

    1990-01-01

    Apparatus for analyzing aerosols in essentially real time includes a virtual impactor which separates coarse particles from fine and ultrafine particles in an aerosol sample. The coarse and ultrafine particles are captured in PTFE filters, and the fine particles impact onto an internal light reflection element. The composition and quantity of the particles on the PTFE filter and on the internal reflection element are measured by alternately passing infrared light through the filter and the internal light reflection element, and analyzing the light through infrared spectrophotometry to identify the particles in the sample.

  6. Stackable differential mobility analyzer for aerosol measurement

    DOEpatents

    Cheng, Meng-Dawn; Chen, Da-Ren

    2007-05-08

    A multi-stage differential mobility analyzer (MDMA) for aerosol measurements includes a first electrode or grid including at least one inlet or injection slit for receiving an aerosol including charged particles for analysis. A second electrode or grid is spaced apart from the first electrode. The second electrode has at least one sampling outlet disposed at a plurality different distances along its length. A volume between the first and the second electrode or grid between the inlet or injection slit and a distal one of the plurality of sampling outlets forms a classifying region, the first and second electrodes for charging to suitable potentials to create an electric field within the classifying region. At least one inlet or injection slit in the second electrode receives a sheath gas flow into an upstream end of the classifying region, wherein each sampling outlet functions as an independent DMA stage and classifies different size ranges of charged particles based on electric mobility simultaneously.

  7. Atmospheric Aerosol Chemistry Analyzer: Demonstration of feasibility

    SciTech Connect

    Mroz, E.J.; Olivares, J.; Kok, G.

    1996-04-01

    This is the final report of a three-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The project objective was to demonstrate the technical feasibility of an Atmospheric Aerosol Chemistry Analyzer (AACA) that will provide a continuous, real-time analysis of the elemental (major, minor and trace) composition of atmospheric aerosols. The AACA concept is based on sampling the atmospheric aerosol through a wet cyclone scrubber that produces an aqueous suspension of the particles. This suspension can then be analyzed for elemental composition by ICP/MS or collected for subsequent analysis by other methods. The key technical challenge was to develop a wet cyclone aerosol sampler suitable for respirable particles found in ambient aerosols. We adapted an ultrasonic nebulizer to a conventional, commercially available, cyclone aerosol sampler and completed collection efficiency tests for the unit, which was shown to efficiently collect particles as small as 0.2 microns. We have completed the necessary basic research and have demonstrated the feasibility of the AACA concept.

  8. IMPLEMENTATION OF A MICROCOMPUTER-MODIFIED ELECTRICAL AEROSOL ANALYZER

    EPA Science Inventory

    A commercial electrical aerosol analyzer has been modified through addition of a digital voltmeter, a microcomputer, and a printer. In unattended operation, the system can acquire a differential particle size distribution, print and plot the resulting spectrum in any of three pos...

  9. Electronic cigarette aerosol particle size distribution measurements.

    PubMed

    Ingebrethsen, Bradley J; Cole, Stephen K; Alderman, Steven L

    2012-12-01

    The particle size distribution of aerosols produced by electronic cigarettes was measured in an undiluted state by a spectral transmission procedure and after high dilution with an electrical mobility analyzer. The undiluted e-cigarette aerosols were found to have particle diameters of average mass in the 250-450 nm range and particle number concentrations in the 10(9) particles/cm(3) range. These measurements are comparable to those observed for tobacco burning cigarette smoke in prior studies and also measured in the current study with the spectral transmission method and with the electrical mobility procedure. Total particulate mass for the e-cigarettes calculated from the size distribution parameters measured by spectral transmission were in good agreement with replicate determinations of total particulate mass by gravimetric filter collection. In contrast, average particle diameters determined for e-cigarettes by the electrical mobility method are in the 50 nm range and total particulate masses calculated based on the suggested diameters are orders of magnitude smaller than those determined gravimetrically. This latter discrepancy, and the very small particle diameters observed, are believed to result from almost complete e-cigarette aerosol particle evaporation at the dilution levels and conditions of the electrical mobility analysis. A much smaller degree, ~20% by mass, of apparent particle evaporation was observed for tobacco burning cigarette smoke. The spectral transmission method is validated in the current study against measurements on tobacco burning cigarette smoke, which has been well characterized in prior studies, and is supported as yielding an accurate characterization of the e-cigarette aerosol particle size distribution. PMID:23216158

  10. Spatial Variability of CCN Sized Aerosol Particles

    NASA Astrophysics Data System (ADS)

    Asmi, A.; Väänänen, R.

    2014-12-01

    The computational limitations restrict the grid size used in GCM models, and for many cloud types they are too large when compared to the scale of the cloud formation processes. Several parameterizations for e.g. convective cloud formation exist, but information on spatial subgrid variation of the cloud condensation nuclei (CCNs) sized aerosol concentration is not known. We quantify this variation as a function of the spatial scale by using datasets from airborne aerosol measurement campaigns around the world including EUCAARI LONGREX, ATAR, INCA, INDOEX, CLAIRE, PEGASOS and several regional airborne campaigns in Finland. The typical shapes of the distributions are analyzed. When possible, we use information obtained by CCN counters. In some other cases, we use particle size distribution measured by for example SMPS to get approximated CCN concentration. Other instruments used include optical particle counters or condensational particle counters. When using the GCM models, the CCN concentration used for each the grid-box is often considered to be either flat, or as an arithmetic mean of the concentration inside the grid-box. However, the aircraft data shows that the concentration values are often lognormal distributed. This, combined with the subgrid variations in the land use and atmospheric properties, might cause that the aerosol-cloud interactions calculated by using mean values to vary significantly from the true effects both temporary and spatially. This, in turn, can cause non-linear bias into the GCMs. We calculate the CCN aerosol concentration distribution as a function of different spatial scales. The measurements allow us to study the variation of these distributions within from hundreds of meters up to hundreds of kilometers. This is used to quantify the potential error when mean values are used in GCMs.

  11. Aerosol and air pollution size distribution

    NASA Astrophysics Data System (ADS)

    Shani, Gad; Haccoun, A.; Kushelevsky, A.

    The size distribution of aerosols was measured in a moderately industrial city, in a semi-arid zone on the Negev desert border. The aerosols in the city of Beer Sheva are from two sources: the dust coming from the desert and urban pollution. The size measurements were done with a cascade impactor. The elemental content of the aerosols was investigated by neutron activation analysis and X-ray fluorescence. The main elements of the dust are: Ca, Si, Fe, Na and the trace elements are: Sc, Se, La, Sm, Hf and others. The main elements of the urban pollution are S, Br, Pb, Cl, Hg and others. It was found that the elements belonging to each group can easily be classified by the size distribution. The analytical consideration of the aerosol size distribution of each group are discussed and two corresponding analytical expressions are suggested. It is shown that aerosols originating in the dust have a hump shape distribution around ~ 4μm, and those originating in urban pollution have a distribution decreasing with increasing aerosol diameter. Many examples are given to prove the conclusions.

  12. Aerosol size distribution seasonal characteristics measured in Tiksi, Russian Arctic

    NASA Astrophysics Data System (ADS)

    Asmi, E.; Kondratyev, V.; Brus, D.; Laurila, T.; Lihavainen, H.; Backman, J.; Vakkari, V.; Aurela, M.; Hatakka, J.; Viisanen, Y.; Uttal, T.; Ivakhov, V.; Makshtas, A.

    2015-07-01

    Four years of continuous aerosol number size distribution measurements from an Arctic Climate Observatory in Tiksi Russia are analyzed. Source region effects on particle modal features, and number and mass concentrations are presented for different seasons. The monthly median total aerosol number concentration in Tiksi ranges from 184 cm-3 in November to 724 cm-3 in July with a local maximum in March of 481 cm-3. The total mass concentration has a distinct maximum in February-March of 1.72-2.38 μg m-3 and two minimums in June of 0.42 μg m-3 and in September-October of 0.36-0.57 μg m-3. These seasonal cycles in number and mass concentrations are related to isolated aerosol sources such as Arctic haze in early spring which increases accumulation and coarse mode numbers, and biogenic emissions in summer which affects the smaller, nucleation and Aitken mode particles. The impact of temperature dependent natural emissions on aerosol and cloud condensation nuclei numbers was significant. Therefore, in addition to the precursor emissions of biogenic volatile organic compounds, the frequent Siberian forest fires, although far are suggested to play a role in Arctic aerosol composition during the warmest months. During calm and cold months aerosol concentrations were occasionally increased by nearby aerosol sources in trapping inversions. These results provide valuable information on inter-annual cycles and sources of Arctic aerosols.

  13. A laser analyzer of aerosol dispersion

    NASA Astrophysics Data System (ADS)

    Kairo, V. S.; Smirnov, V. V.

    1980-10-01

    A small He-Ne laser, wide-angle reflecting optics, an electrostatic diluent, and a graduated measuring device provided a wide range of particle sizing (0.2 to 20 microns) at concentrations ranging from 0.01 to one million particles/cu cm. The device was calibrated by measuring particles of polystyrene, a melamine-formaldehyde resin, aluminum, magnesium, willow seeds, and club moss.

  14. Analytic modeling of aerosol size distributions

    NASA Technical Reports Server (NTRS)

    Deepack, A.; Box, G. P.

    1979-01-01

    Mathematical functions commonly used for representing aerosol size distributions are studied parametrically. Methods for obtaining best fit estimates of the parameters are described. A catalog of graphical plots depicting the parametric behavior of the functions is presented along with procedures for obtaining analytical representations of size distribution data by visual matching of the data with one of the plots. Examples of fitting the same data with equal accuracy by more than one analytic model are also given.

  15. Indoor aerosol size distributions in a gymnasium.

    PubMed

    Castro, Amaya; Calvo, Ana I; Alves, Célia; Alonso-Blanco, Elisabeth; Coz, Esther; Marques, Liliana; Nunes, Teresa; Fernández-Guisuraga, Jose Manuel; Fraile, Roberto

    2015-08-15

    In this study, an indoor/outdoor monitoring program was carried out in a gymnasium at the University of Leon, Spain. The main goal was a characterization of aerosol size distributions in a university gymnasium under different conditions and sports activities (with and without magnesia alba) and the study of the mass fraction deposited in each of the parts of the respiratory tract. The aerosol particles were measured in 31 discrete channels (size ranges) using a laser spectrometer probe. Aerosol size distributions were studied under different conditions: i) before sports activities, ii) activities without using magnesia alba, iii) activities using magnesia alba, iv) cleaning procedures, and v) outdoors. The aerosol refractive index and density indoors were estimated from the aerosol composition: 1.577-0.003i and 2.055 g cm(-3), respectively. Using the estimated density, the mass concentration was calculated, and the evolution of PM1, PM2.5 and PM10 for different activities was assessed. The quality of the air in the gymnasium was strongly influenced by the use of magnesia alba (MgCO3) and the number of gymnasts who were training. Due to the climbing chalk and the constant process of resuspension, average PM10 concentrations of over 440 μg m(-3) were reached. The maximum daily concentrations ranged from 500 to 900 μg m(-3). Particle size determines the place in the respiratory tract where the deposition occurs. For this reason, the inhalable, thoracic, tracheobronchial and respirable fractions were assessed for healthy adults and high risk people, according to international standards. The estimations show that, for healthy adults, up to 300 μg m(-3) can be retained by the trachea and bronchi, and 130 μg m(-3) may reach the alveolar region. The different physical activities and the attendance rates in the sports facility have a significant influence on the concentration and size distributions observed. PMID:25897726

  16. Retrieval of particle size distribution from aerosol optical thickness using an improved particle swarm optimization algorithm

    NASA Astrophysics Data System (ADS)

    Mao, Jiandong; Li, Jinxuan

    2015-10-01

    Particle size distribution is essential for describing direct and indirect radiation of aerosols. Because the relationship between the aerosol size distribution and optical thickness (AOT) is an ill-posed Fredholm integral equation of the first type, the traditional techniques for determining such size distributions, such as the Phillips-Twomey regularization method, are often ambiguous. Here, we use an approach based on an improved particle swarm optimization algorithm (IPSO) to retrieve aerosol size distribution. Using AOT data measured by a CE318 sun photometer in Yinchuan, we compared the aerosol size distributions retrieved using a simple genetic algorithm, a basic particle swarm optimization algorithm and the IPSO. Aerosol size distributions for different weather conditions were analyzed, including sunny, dusty and hazy conditions. Our results show that the IPSO-based inversion method retrieved aerosol size distributions under all weather conditions, showing great potential for similar size distribution inversions.

  17. Remote Laser Diffraction Particle Size Distribution Analyzer

    SciTech Connect

    Batcheller, Thomas Aquinas; Huestis, Gary Michael; Bolton, Steven Michael

    2001-03-01

    In support of a radioactive slurry sampling and physical characterization task, an “off-the-shelf” laser diffraction (classical light scattering) particle size analyzer was utilized for remote particle size distribution (PSD) analysis. Spent nuclear fuel was previously reprocessed at the Idaho Nuclear Technology and Engineering Center (INTEC—formerly recognized as the Idaho Chemical Processing Plant) which is on DOE’s INEEL site. The acidic, radioactive aqueous raffinate streams from these processes were transferred to 300,000 gallon stainless steel storage vessels located in the INTEC Tank Farm area. Due to the transfer piping configuration in these vessels, complete removal of the liquid can not be achieved. Consequently, a “heel” slurry remains at the bottom of an “emptied” vessel. Particle size distribution characterization of the settled solids in this remaining heel slurry, as well as suspended solids in the tank liquid, is the goal of this remote PSD analyzer task. A Horiba Instruments Inc. Model LA-300 PSD analyzer, which has a 0.1 to 600 micron measurement range, was modified for remote application in a “hot cell” (gamma radiation) environment. This technology provides rapid and simple PSD analysis, especially down in the fine and microscopic particle size regime. Particle size analysis of these radioactive slurries down in this smaller range was not previously achievable—making this technology far superior than the traditional methods used. Successful acquisition of this data, in conjunction with other characterization analyses, provides important information that can be used in the myriad of potential radioactive waste management alternatives.

  18. Particle size distribution of indoor aerosol sources

    SciTech Connect

    Shah, K.B.

    1990-10-24

    As concern about Indoor Air Quality (IAQ) has grown in recent years, it has become necessary to determine the nature of particles produced by different indoor aerosol sources and the typical concentration that these sources tend to produce. These data are important in predicting the dose of particles to people exposed to these sources and it will also enable us to take effective mitigation procedures. Further, it will also help in designing appropriate air cleaners. A new state of the art technique, DMPS (Differential Mobility Particle Sizer) System is used to determine the particle size distributions of a number of sources. This system employs the electrical mobility characteristics of these particles and is very effective in the 0.01--1.0 {mu}m size range. A modified system that can measure particle sizes in the lower size range down to 3 nm was also used. Experimental results for various aerosol sources is presented in the ensuing chapters. 37 refs., 20 figs., 2 tabs.

  19. SAGE II aerosol data validation based on retrieved aerosol model size distribution from SAGE II aerosol measurements

    NASA Technical Reports Server (NTRS)

    Wang, Pi-Huan; Mccormick, M. P.; Mcmaster, L. R.; Chu, W. P.; Swissler, T. J.; Osborn, M. T.; Russell, P. B.; Oberbeck, V. R.; Livingston, J.; Rosen, J. M.

    1989-01-01

    Consideration is given to aerosol correlative measurements experiments for the Stratospheric Aerosol and Gas Experiment (SAGE) II, conducted between November 1984 and July 1986. The correlative measurements were taken with an impactor/laser probe, a dustsonde, and an airborne 36-cm lidar system. The primary aerosol quantities measured by the ground-based instruments are compared with those calculated from the aerosol size distributions from SAGE II aerosol extinction measurements. Good agreement is found between the two sets of measurements.

  20. Aerosol size distribution seasonal characteristics measured in Tiksi, Russian Arctic

    NASA Astrophysics Data System (ADS)

    Asmi, E.; Kondratyev, V.; Brus, D.; Laurila, T.; Lihavainen, H.; Backman, J.; Vakkari, V.; Aurela, M.; Hatakka, J.; Viisanen, Y.; Uttal, T.; Ivakhov, V.; Makshtas, A.

    2016-02-01

    Four years of continuous aerosol number size distribution measurements from the Arctic Climate Observatory in Tiksi, Russia, are analyzed. Tiksi is located in a region where in situ information on aerosol particle properties has not been previously available. Particle size distributions were measured with a differential mobility particle sizer (in the diameter range of 7-500 nm) and with an aerodynamic particle sizer (in the diameter range of 0.5-10 μm). Source region effects on particle modal features and number, and mass concentrations are presented for different seasons. The monthly median total aerosol number concentration in Tiksi ranges from 184 cm-3 in November to 724 cm-3 in July, with a local maximum in March of 481 cm-3. The total mass concentration has a distinct maximum in February-March of 1.72-2.38 μg m-3 and two minimums in June (0.42 μg m-3) and in September-October (0.36-0.57 μg m-3). These seasonal cycles in number and mass concentrations are related to isolated processes and phenomena such as Arctic haze in early spring, which increases accumulation and coarse-mode numbers, and secondary particle formation in spring and summer, which affects the nucleation and Aitken mode particle concentrations. Secondary particle formation was frequently observed in Tiksi and was shown to be slightly more common in marine, in comparison to continental, air flows. Particle formation rates were the highest in spring, while the particle growth rates peaked in summer. These results suggest two different origins for secondary particles, anthropogenic pollution being the important source in spring and biogenic emissions being significant in summer. The impact of temperature-dependent natural emissions on aerosol and cloud condensation nuclei numbers was significant: the increase in both the particle mass and the CCN (cloud condensation nuclei) number with temperature was found to be higher than in any previous study done over the boreal forest region. In addition

  1. Physicochemical characterization of Capstone depleted uranium aerosols I: uranium concentration in aerosols as a function of time and particle size.

    PubMed

    Parkhurst, Mary Ann; Cheng, Yung Sung; Kenoyer, Judson L; Traub, Richard J

    2009-03-01

    During the Capstone Depleted Uranium (DU) Aerosol Study, aerosols containing DU were produced inside unventilated armored vehicles (i.e., Abrams tanks and Bradley Fighting Vehicles) by perforation with large-caliber DU penetrators. These aerosols were collected and characterized, and the data were subsequently used to assess human health risks to personnel exposed to DU aerosols. The DU content of each aerosol sample was first quantified by radioanalytical methods, and selected samples, primarily those from the cyclone separator grit chambers, were analyzed radiochemically. Deposition occurred inside the vehicles as particles settled on interior surfaces. Settling rates of uranium from the aerosols were evaluated using filter cassette samples that collected aerosol as total mass over eight sequential time intervals. A moving filter was used to collect aerosol samples over time, particularly within the first minute after a shot. The results demonstrate that the peak uranium concentration in the aerosol occurred in the first 10 s after perforation, and the concentration decreased in the Abrams tank shots to about 50% within 1 min and to less than 2% after 30 min. The initial and maximum uranium concentrations were lower in the Bradley vehicle than those observed in the Abrams tank, and the concentration levels decreased more slowly. Uranium mass concentrations in the aerosols as a function of particle size were evaluated using samples collected in a cyclone sampler, which collected aerosol continuously for 2 h after perforation. The percentages of uranium mass in the cyclone separator stages ranged from 38 to 72% for the Abrams tank with conventional armor. In most cases, it varied with particle size, typically with less uranium associated with the smaller particle sizes. Neither the Abrams tank with DU armor nor the Bradley vehicle results were specifically correlated with particle size and can best be represented by their average uranium mass concentrations of 65

  2. Physicochemical Characterization of Capstone Depleted Uranium Aerosols I: Uranium Concentration in Aerosols as a Function of Time and Particle Size

    SciTech Connect

    Parkhurst, MaryAnn; Cheng, Yung-Sung; Kenoyer, Judson L.; Traub, Richard J.

    2009-03-01

    During the Capstone Depleted Uranium (DU) Aerosol Study, aerosols containing depleted uranium were produced inside unventilated armored vehicles (i.e., Abrams tanks and Bradley Fighting Vehicles) by perforation with large-caliber DU penetrators. These aerosols were collected and characterized, and the data were subsequently used to assess human health risks to personnel exposed to DU aerosols. The DU content of each aerosol sample was first quantified by radioanalytical methods, and selected samples, primarily those from the cyclone separator grit chambers, were analyzed radiochemically. Deposition occurred inside the vehicles as particles settled on interior surfaces. Settling rates of uranium from the aerosols were evaluated using filter cassette samples that collected aerosol as total mass over eight sequential time intervals. A moving filter was used to collect aerosol samples over time particularly within the first minute after the shot. The results demonstrate that the peak uranium concentration in the aerosol occurred in the first 10 s, and the concentration decreased in the Abrams tank shots to about 50% within 1 min and to less than 2% 30 min after perforation. In the Bradley vehicle, the initial (and maximum) uranium concentration was lower than those observed in the Abrams tank and decreased more slowly. Uranium mass concentrations in the aerosols as a function of particle size were evaluated using samples collected in the cyclone samplers, which collected aerosol continuously for 2 h post perforation. The percentages of uranium mass in the cyclone separator stages from the Abrams tank tests ranged from 38% to 72% and, in most cases, varied with particle size, typically with less uranium associated with the smaller particle sizes. Results with the Bradley vehicle ranged from 18% to 29% and were not specifically correlated with particle size.

  3. A rocket-borne mass analyzer for charged aerosol particles in the mesosphere

    SciTech Connect

    Knappmiller, Scott; Robertson, Scott; Sternovsky, Zoltan; Friedrich, Martin

    2008-10-15

    An electrostatic mass spectrometer for nanometer-sized charged aerosol particles in the mesosphere has been developed and tested. The analyzer is mounted on the forward end of a rocket and has a slit opening for admitting a continuous sample of air that is exhausted through ports at the sides. Within the instrument housing are two sets of four collection plates that are biased with positive and negative voltages for the collection of negative and positive aerosol particles, respectively. Each collection plate spans about an order of magnitude in mass which corresponds to a factor of 2 in radius. The number density of the charge is calculated from the current collected by the plates. The mean free path for molecular collisions in the mesosphere is comparable to the size of the instrument opening; thus, the analyzer performance is modeled by a Monte Carlo computer code that finds the aerosol particles trajectories within the instrument including both the electrostatic force and the forces from collisions of the aerosol particles with air molecules. Mass sensitivity curves obtained using the computer models are near to those obtained in the laboratory using an ion source. The first two flights of the instrument returned data showing the charge number densities of both positive and negative aerosol particles in four mass ranges.

  4. Transfer learning used to analyze the dynamic evolution of the dust aerosol

    NASA Astrophysics Data System (ADS)

    Ma, Yingying; Gong, Wei; Mao, Feiyue

    2015-03-01

    To keep the advantage of Support Vector Machine (SVM) in analyzing the dynamic evolution of the dust aerosol, we introduce transfer learning as a new method because transfer learning can utilize knowledge from previously collected data and add dozens of new samples, which can significantly improve dust and cloud classification results. It can also reduce the time of sample collection and make learning efficient. In this paper, we receive significant improvement effect using SVM as the basic learner in TrAdaBoost during four consecutive dust storm days, and correct one error classification in PDF. As a result, dust aerosol in high altitude can even spread to stratosphere. Moreover, in the process of dust aerosol transportation, it is highly affected by anthropogenic aerosol, for example, the color ratio (CR) changes from 0.728 to 0.460 and finally reaches 0.466, while depolarization ratio (DR) changes from 0.308 to 0.081 and finally reaches 0.156. It is indicated that the big size and non-spherical aerosol particles reduce obviously after dust aerosol deposition, but small size and spherical anthropogenic aerosol also produce a certain effect, and on March 22, 2010 had a small recovery above the ocean following the reduction of DR and CR. Due to the MODIS resolution not meeting the observation requirement and layer identification being different between CALIPSO and CloudSat, a problem such as stratocumulus cloud in low altitude still exists in aerosol and cloud classification. Lack of ground-based auxiliary data is the main problem which hinders our validation and quantitative analysis. It is pressing for a solution in future.

  5. A New Method to Generate Micron-Sized AerosolS With Narrow Size Distribution

    NASA Astrophysics Data System (ADS)

    Gañón-Calvo, Alfonso; Barrero, Antonio

    1996-11-01

    Aerosols in the micron-size range with a remarkable monodisperse size distribution can be generated from the breaking up process of a capillary microjet. The size of the main droplets and satellites depend on the jet diameter, d_j, as well as the flow rate, Q, and liquid properties which eventually determine the jet`s breaking up. Therefore, the generation and control of capillary microjets is essential to produce sprays of small droplets with narrow size histograms. Electrosprays has been up to now one of the most successful techniques to produce monodisperse micron-size aerosols. As an alternative, we report here a new method, aerospray, to generate capillary micro jets which can compete against the electrospray for the production of aerosols of small droplets with very narrow size distribution. The method is outlined in the following. Liquid coming out from the exit of a capillary needle is sucked by means of a high speed gas stream (usually air) which flows throughout a hole separating two chambers at different pressures. Under certain parametric conditions of liquid properties, liquid and air flow rates, and geometric characteristics (needle and hole diameters, distance from the needle to the hole, etc), the liquid forms a steady capillary microjet of very small diameter which is speeded up an stabilized by the action of the viscous stresses at the gas liquid interface. The jet passes through the hole and goes out the outside chamber where eventually breaks up into microdroplets by varicose instabilities. Measurements from Laser-Doppler PDA Analizer of these aerosprays show that both the droplet size and its standard deviation are comparable to those obtained by electrospray techniques. On the other hand, using the aerospray, the standard deviation of the resulting droplet size distribution is of the order of those that can be obtained by ultrasonic atomization but the mean diameters can be more than one order of magnitude smaller.

  6. Size distribution and scattering phase function of aerosol particles retrieved from sky brightness measurements

    NASA Technical Reports Server (NTRS)

    Kaufman, Y. J.; Gitelson, A.; Karnieli, A.; Ganor, E. (Editor); Fraser, R. S.; Nakajima, T.; Mattoo, S.; Holben, B. N.

    1994-01-01

    Ground-based measurements of the solar transmission and sky radiance in a horizontal plane through the Sun are taken in several geographical regions and aerosol types: dust in a desert transition zone in Israel, sulfate particles in Eastern and Western Europe, tropical aerosol in Brazil, and mixed continental/maritime aerosol in California. Stratospheric aerosol was introduced after the eruption of Mount Pinatubo in June 1991. Therefore measurements taken before the eruption are used to analyze the properties of tropospheric aerosol; measurements from 1992 are also used to detect the particle size and concentration of stratospheric aerosol. The measurements are used to retrieve the size distribution and the scattering phase function at large scattering angles of the undisturbed aerosol particles. The retrieved properties represent an average on the entire atmospheric column. A comparison between the retrieved phase function for a scattering angle of 120 deg, with phase function predicted from the retrieved size distribution, is used to test the assumption of particle homogeneity and sphericity in radiative transfer models (Mie theory). The effect was found to be small (20% +/- 15%). For the stratospheric aerosol (sulfates), as expected, the phase function was very well predicted using the Mie theory. A model with a power law distribution, based on the spectral dependence of the optical thickness, alpha, cannot estimate accurately the phase function (up to 50% error for lambda = 0.87 microns). Before the Pinatubo eruption the ratio between the volumes of sulfate and coarse particles was very well correlated with alpha. The Pinatubo stratospheric aerosol destroyed this correlation. The aerosol optical properties are compared with analysis of the size, shape, and composition of the individual particles by electron microscopy of in situ samples. The measured volume size distribution before the injection of stratospheric aerosol consistently show two modes, sulfate

  7. Accounting for dust aerosol size distribution in radiative transfer

    NASA Astrophysics Data System (ADS)

    Li, Jiangnan; Min, Qilong; Peng, Yiran; Sun, Zhian; Zhao, Jian-Qi

    2015-07-01

    The impact of size distribution of mineral dust aerosol on radiative transfer was investigated using the Aerosol Robotic Network-retrieved aerosol size distributions. Three methods for determining the aerosol optical properties using size distributions were discussed. The first is referred to as a bin method in which the aerosol optical properties are determined for each bin of the size distribution. The second is named as an assembly mean method in which the aerosol optical properties are determined with an integration of the aerosol optical parameters over the observed size distribution. The third is a normal parameterization method based on an assumed size distribution. The bin method was used to generate the benchmark results in the radiation calculations against the methods of the assembly mean, and parameterizations based on two size distribution functions, namely, lognormal and gamma were examined. It is seen that the assembly mean method can produce aerosol radiative forcing with accuracy of better than 1%. The accuracies of the parameterizations based on lognormal and gamma size distributions are about 25% and 5%, respectively. Both the lognormal and gamma size distributions can be determined by two parameters, the effective radius and effective variance. The better results from the gamma size distribution can be explained by a third parameter of skewness which is found to be useful for judging how close the assumed distribution is to the observation result. The parameterizations based on the two assumed size distributions are also evaluated in a climate model. The results show that the reflected solar fluxes over the desert areas determined by the scheme based on the gamma size distribution are about 1 W m-2 less than those from the scheme based on the lognormal size distribution, bringing the model results closer to the observations.

  8. Sources of Size Segregated Sulfate Aerosols in the Arctic Summer

    NASA Astrophysics Data System (ADS)

    Ghahremaninezhadgharelar, R.; Norman, A. L.; Abbatt, J.; Levasseur, M.

    2015-12-01

    Aerosols drive significant radiative forcing and affect Arctic climate. Despite the importance of these particles in Arctic climate change, there are some key uncertainties in the estimation of their effects and sources. Aerosols in six size fractions between <0.49 to 7.0 microns in diameter were collected on board the Canadian Coast Guard Ship (CCGS) Amundsen in the Arctic, during July 2014. A cascade impactor fitted to a high volume sampler was used for this study and was modified to permit collection of SO2 after aerosols were removed from the gas stream. The isotopic composition of sulfate aerosols and SO2 was measured and apportionment calculations have been performed to quantify the contribution of biogenic as well as anthropogenic sources to the growth of different aerosol size fractions in the atmosphere. The presence of sea salt sulfate aerosols was especially high in coarse mode aerosols as expected. The contribution of biogenic sulfate concentration in this study was higher than anthropogenic sulfate. Around 70% of fine aerosols (<0.49 μm) and 86% of SO2 were from biogenic sources. Concentrations of biogenic sulfate for fine aerosols, ranging from 18 to 625 ng/m3, were five times higher than total biogenic sulfate concentrations measured during Fall in the same region (Rempillo et al., 2011). A comparison of the isotope ratio for SO2 and fine aerosols offers a way to determine aerosol growth from local SO2 oxidation. For some samples, the values for SO2 and fine aerosols were close together suggesting the same source for SO2 and aerosol sulfur.Aerosols drive significant radiative forcing and affect Arctic climate. Despite the importance of these particles in Arctic climate change, there are some key uncertainties in the estimation of their effects and sources. Aerosols in six size fractions between <0.49 to 7.0 microns in diameter were collected on board the Canadian Coast Guard Ship (CCGS) Amundsen in the Arctic, during July 2014. A cascade impactor

  9. Particle size distributions of several commonly used seeding aerosols

    NASA Technical Reports Server (NTRS)

    Crosswy, F. L.

    1985-01-01

    During the course of experimentation, no solid particle powder could be found which produced an aerosol with a narrow particle size distribution when fluidization was the only flow process used in producing the aerosol. The complication of adding particle size fractionation processes to the aerosol generation effort appears to be avoidable. In this regard, a simple sonic orifice is found to be effective in reducing the percentage of agglomerates in the several metal oxide powders tested. Marginally beneficial results are obtained for a 0.5/99.5 percent by weight mixture of the flow agent and metal oxide powder. However, agglomeration is observed to be enhanced when the flow agent percentage is increased to 5 percent. Liquid atomization using the Collison nebulizer as well as a version of the Laskin nozzle resulted in polydispersed aerosols with particle size distributions heavily weighted by the small particle end of the size spectrum. The aerosol particle size distributions produced by the vaporization/condensation seeder are closer to the ideal monodispersed aerosol than any of the other aerosols tested. In addition, this seeding approach affords a measure of control over particle size and particle production rate.

  10. Initial size distributions and hygroscopicity of indoor combustion aerosol particles

    SciTech Connect

    Li, W.; Hopke, P.K.

    1993-10-01

    Cigarette smoke, incense smoke, natural gas flames, propane fuel flames, and candle flames are contributors of indoor aerosol particles. To provide a quantitative basis for the modeling of inhaled aerosol deposition pattern, the hygroscopic growth of particles from these five sources as well as the source size distributions were measured. Because the experiments were performed on the bases of particles of single size, it provided not only the averaged particle`s hygroscopic growth of each source, but also the detailed size change for particles of different sizes within the whole size spectrum. The source particle size distribution measurements found that cigarette smoke and incense smoke contained particles in the size range of 100-700 nm, while the natural gas, propane, and candle flames generated particles between 10 and 100 nm. The hygroscopic growth experiments showed that these combustion aerosol particles could grow 10% to 120%, depending on the particle sizes and origins. 18 refs., 15 figs., 3 tabs.

  11. Experimental determination of size distributions: analyzing proper sample sizes

    NASA Astrophysics Data System (ADS)

    Buffo, A.; Alopaeus, V.

    2016-04-01

    The measurement of various particle size distributions is a crucial aspect for many applications in the process industry. Size distribution is often related to the final product quality, as in crystallization or polymerization. In other cases it is related to the correct evaluation of heat and mass transfer, as well as reaction rates, depending on the interfacial area between the different phases or to the assessment of yield stresses of polycrystalline metals/alloys samples. The experimental determination of such distributions often involves laborious sampling procedures and the statistical significance of the outcome is rarely investigated. In this work, we propose a novel rigorous tool, based on inferential statistics, to determine the number of samples needed to obtain reliable measurements of size distribution, according to specific requirements defined a priori. Such methodology can be adopted regardless of the measurement technique used.

  12. Size Resolved Measurements of Springtime Aerosol Particles over the Northern South China Sea

    NASA Technical Reports Server (NTRS)

    Atwood, Samuel A.; Reid, Jeffrey S.; Kreidenweis, Sonia M.; Cliff, Stephen S.; Zhao, Yongjing; Lin, Neng-Huei; Tsay, Si-Chee; Chu, Yu-Chi; Westphal, Douglas L.

    2012-01-01

    Large sources of aerosol particles and their precursors are ubiquitous in East Asia. Such sources are known to impact the South China Sea (henceforth SCS), a sometimes heavily polluted region that has been suggested as particularly vulnerable to climate change. To help elucidate springtime aerosol transport into the SCS, an intensive study was performed on the remote Dongsha (aka Pratas) Islands Atoll in spring 2010. As part of this deployment, a Davis Rotating-drum Uniform size-cut Monitor (DRUM) cascade impactor was deployed to collect size-resolved aerosol samples at the surface that were analyzed by X-ray fluorescence for concentrations of selected elements. HYSPLIT backtrajectories indicated that the transport of aerosol observed at the surface at Dongsha was occurring primarily from regions generally to the north and east. This observation was consistent with the apparent persistence of pollution and dust aerosol, along with sea salt, in the ground-based dataset. In contrast to the sea-level observations, modeled aerosol transport suggested that the westerly flow aloft (w700 hPa) transported smoke-laden air toward the site from regions from the south and west. Measured aerosol optical depth at the site was highest during time periods of modeled heavy smoke loadings aloft. These periods did not coincide with elevated aerosol concentrations at the surface, although the model suggested sporadic mixing of this free-tropospheric aerosol to the surface over the SCS. A biomass burning signature was not clearly identified in the surface aerosol composition data, consistent with this aerosol type remaining primarily aloft and not mixing strongly to the surface during the study. Significant vertical wind shear in the region also supports the idea that different source regions lead to varying aerosol impacts in different vertical layers, and suggests the potential for considerable vertical inhomogeneity in the SCS aerosol environment.

  13. Measurements of Hygroscopicity- and Size-Resolved Sea Spray Aerosol

    NASA Astrophysics Data System (ADS)

    Phillips, B.; Dawson, K. W.; Royalty, T. M.; Reed, R. E.; Petters, M.; Meskhidze, N.

    2015-12-01

    Atmospheric aerosols play a central role in many environmental processes by influencing the Earth's radiative balance, tropospheric chemistry, clouds, biogeochemical cycles, and visibility as well as adversely impacting human health. Based on their origin, atmospheric aerosols can be defined as anthropogenic or natural. Recent studies have shown that a large fraction of uncertainty in the radiative effects of anthropogenic aerosols is related to uncertainty in natural—background—aerosols. Marine aerosols are of particular interest due to the abundance of oceans covering the Earth's surface. Despite their importance, limited information is currently available for size- and composition-resolved marine aerosol emission fluxes. Our group has designed and built an instrument for measuring the size- and hygroscopicity-resolved sea spray aerosol fluxes. The instrument was first deployed during spring 2015 at the end of the 560 m pier of the US Army Corps of Engineers' Field Research Facility in Duck, NC. Measurements include 200 nm-sized diameter growth factor (hygroscopicity) distributions, sea spray particle flux measurements, and total sub-micron sized aerosol concentration. Ancillary ocean data includes salinity, pH, sea surface temperature, dissolved oxygen content, and relative fluorescence (proxy for [Chl-a]). Hygroscopicity distribution measurements show two broad peaks, one indicative of organics and sulfates and another suggestive of sea salt. The fraction of 200 nm-sized salt particles having hygroscopicity similar to that of sea-spray aerosol contributes up to ~24% of the distribution on days with high-speed onshore winds and up to ~3% on calm days with winds blowing from the continent. However, the total concentration of sea-spray-like particles originating from offshore versus onshore winds was relatively similar. Changes in the relative contribution of sea-salt to number concentration were caused by a concomitant changes in total aerosol concentration

  14. Impact of aerosol size representation on modeling aerosol-cloud interactions

    SciTech Connect

    Zhang, Y.; Easter, R. C.; Ghan, S. J.; Abdul-Razzak, H.

    2002-11-07

    In this study, we use a 1-D version of a climate-aerosol-chemistry model with both modal and sectional aerosol size representations to evaluate the impact of aerosol size representation on modeling aerosol-cloud interactions in shallow stratiform clouds observed during the 2nd Aerosol Characterization Experiment. Both the modal (with prognostic aerosol number and mass or prognostic aerosol number, surface area and mass, referred to as the Modal-NM and Modal-NSM) and the sectional approaches (with 12 and 36 sections) predict total number and mass for interstitial and activated particles that are generally within several percent of references from a high resolution 108-section approach. The modal approach with prognostic aerosol mass but diagnostic number (referred to as the Modal-M) cannot accurately predict the total particle number and surface areas, with deviations from the references ranging from 7-161%. The particle size distributions are sensitive to size representations, with normalized absolute differences of up to 12% and 37% for the 36- and 12-section approaches, and 30%, 39%, and 179% for the Modal-NSM, Modal-NM, and Modal-M, respectively. For the Modal-NSM and Modal-NM, differences from the references are primarily due to the inherent assumptions and limitations of the modal approach. In particular, they cannot resolve the abrupt size transition between the interstitial and activated aerosol fractions. For the 12- and 36-section approaches, differences are largely due to limitations of the parameterized activation for non-log-normal size distributions, plus the coarse resolution for the 12-section case. Differences are larger both with higher aerosol (i.e., less complete activation) and higher SO2 concentrations (i.e., greater modification of the initial aerosol distribution).

  15. Impact of aerosol size representation on modeling aerosol-cloud interactions

    DOE PAGESBeta

    Zhang, Y.; Easter, R. C.; Ghan, S. J.; Abdul-Razzak, H.

    2002-11-07

    In this study, we use a 1-D version of a climate-aerosol-chemistry model with both modal and sectional aerosol size representations to evaluate the impact of aerosol size representation on modeling aerosol-cloud interactions in shallow stratiform clouds observed during the 2nd Aerosol Characterization Experiment. Both the modal (with prognostic aerosol number and mass or prognostic aerosol number, surface area and mass, referred to as the Modal-NM and Modal-NSM) and the sectional approaches (with 12 and 36 sections) predict total number and mass for interstitial and activated particles that are generally within several percent of references from a high resolution 108-section approach.more » The modal approach with prognostic aerosol mass but diagnostic number (referred to as the Modal-M) cannot accurately predict the total particle number and surface areas, with deviations from the references ranging from 7-161%. The particle size distributions are sensitive to size representations, with normalized absolute differences of up to 12% and 37% for the 36- and 12-section approaches, and 30%, 39%, and 179% for the Modal-NSM, Modal-NM, and Modal-M, respectively. For the Modal-NSM and Modal-NM, differences from the references are primarily due to the inherent assumptions and limitations of the modal approach. In particular, they cannot resolve the abrupt size transition between the interstitial and activated aerosol fractions. For the 12- and 36-section approaches, differences are largely due to limitations of the parameterized activation for non-log-normal size distributions, plus the coarse resolution for the 12-section case. Differences are larger both with higher aerosol (i.e., less complete activation) and higher SO2 concentrations (i.e., greater modification of the initial aerosol distribution).« less

  16. COMPOSITION OF SIZE-FRACTIONATED AEROSOL IN CHARLESTON, WEST VIRGINIA

    EPA Science Inventory

    Atmospheric aerosols were collected during a 21 day period in late summer of 1976 in Charleston, West Virginia, using five dichotomous virtual impactor samplers simultaneously. The resulting coarse and fine aerosol were analyzed with a variety of physical and chemical methods: gr...

  17. Characterization of the Sunset Semi-Continuous Carbon Aerosol Analyzer

    SciTech Connect

    Bauer, Jace J.; Yu, Xiao-Ying; Cary, R.; Laulainen, Nels S.; Berkowitz, Carl M.

    2009-07-01

    Accurate quantification of carbonaceous aerosols is essential for reducing uncertainty in climate change models and is important for long-term air quality monitoring by government agencies. The field-deployable Sunset Semi-Continuous Organic Carbon/Elemental Carbon Aerosol Analyzer (Sunset OCEC) utilizes a modified National Institute for Occupational Safety and Health thermal-optical method to determine total carbon (TC), organic carbon (OC), and elemental carbon (EC) at near real-time; however, its performance is not yet fully characterized. Two collocated Sunset OCEC Analyzers, Unit A and Unit B, were used to determine the relative standard deviation (RSD) and limit of detection (LOD) between June 23 and July 9, 2007, in Richland, Washington, USA. A high-efficiency particulate air filter was utilized to determine the LODs of both instruments. The RSDs between the two Sunset OCECs were 9.12% for TC, 13.0% for Optical OC, and 8.97% for Thermal OC, indicating good precision between the instruments, although the RSDs for Thermal and Optical EC were higher, 29.0% and 48.3%, respectively. The LOD of Unit A was approximately 0.21 µgC/m3 for TC, Optical OC, and Thermal OC, and ~0.004 µgC/m3 for Optical and Thermal EC. Similarly, Unit B had an LOD of ~0.29 µgC/m3 for TC, Optical OC, and Thermal OC, 0.018 µgC/m3 for Optical EC, and 0.004 µgC/m3 for Thermal EC. Factors that may have contributed to the poor RSDs of Thermal and Optical EC include the low EC mass loading in Richland, minor leakage in the oxygen valve of Unit B, and excessive noise from the non-dispersive infrared (NDIR) laser in Unit B, resulting in scattered Optical EC measurements. Improved RSDs of all OC and EC parameters are expected after the Unit B NDIR is tuned up. Future work should reevaluate the precision of the Sunset OCECs and investigate the differences in various thermal-optical protocols on OCEC quantification.

  18. Parametric retrieval model for estimating aerosol size distribution via the AERONET, LAGOS station.

    PubMed

    Emetere, Moses Eterigho; Akinyemi, Marvel Lola; Akin-Ojo, Omololu

    2015-12-01

    The size characteristics of atmospheric aerosol over the tropical region of Lagos, Southern Nigeria were investigated using two years of continuous spectral aerosol optical depth measurements via the AERONET station for four major bands i.e. blue, green, red and infrared. Lagos lies within the latitude of 6.465°N and longitude of 3.406°E. Few systems of dispersion model was derived upon specified conditions to solve challenges on aerosols size distribution within the Stokes regime. The dispersion model was adopted to derive an aerosol size distribution (ASD) model which is in perfect agreement with existing model. The parametric nature of the formulated ASD model shows the independence of each band to determine the ASD over an area. The turbulence flow of particulates over the area was analyzed using the unified number (Un). A comparative study via the aid of the Davis automatic weather station was carried out on the Reynolds number, Knudsen number and the Unified number. The Reynolds and Unified number were more accurate to describe the atmospheric fields of the location. The aerosols loading trend in January to March (JFM) and August to October (ASO) shows a yearly 15% retention of aerosols in the atmosphere. The effect of the yearly aerosol retention can be seen to partly influence the aerosol loadings between October and February. PMID:26452005

  19. Physicochemical characterization of Capstone depleted uranium aerosols II: particle size distributions as a function of time.

    PubMed

    Cheng, Yung Sung; Kenoyer, Judson L; Guilmette, Raymond A; Parkhurst, Mary Ann

    2009-03-01

    The Capstone Depleted Uranium (DU) Aerosol Study, which generated and characterized aerosols containing DU from perforation of armored vehicles with large-caliber DU penetrators, incorporated a sampling protocol to evaluate particle size distributions. Aerosol particle size distribution is an important parameter that influences aerosol transport and deposition processes as well as the dosimetry of the inhaled particles. These aerosols were collected on cascade impactor substrates using a pre-established time sequence following the firing event to analyze the uranium concentration and particle size of the aerosols as a function of time. The impactor substrates were analyzed using proportional counting, and the derived uranium content of each served as input to the evaluation of particle size distributions. Activity median aerodynamic diameters (AMADs) of the particle size distributions were evaluated using unimodal and bimodal models. The particle size data from the impactor measurements were quite variable. Most size distributions measured in the test based on activity had bimodal size distributions with a small particle size mode in the range of between 0.2 and 1.2 microm and a large size mode between 2 and 15 microm. In general, the evolution of particle size over time showed an overall decrease of average particle size from AMADs of 5 to 10 microm shortly after perforation to around 1 microm at the end of the 2-h sampling period. The AMADs generally decreased over time because of settling. Additionally, the median diameter of the larger size mode decreased with time. These results were used to estimate the dosimetry of inhaled DU particles. PMID:19204485

  20. Comparison of aerosol size distribution in coastal and oceanic environments

    NASA Astrophysics Data System (ADS)

    Kusmierczyk-Michulec, Jolanta; van Eijk, Alexander M.

    2006-08-01

    The results of applying the empirical orthogonal functions (EOF) method to decomposition and approximation of aerosol size distributions are presented. A comparison was made for two aerosol data sets, representing coastal and oceanic environments. The first data set includes measurements collected at the Irish Atlantic coast in 1994 and 1995, the second one data collected during the Rough Evaporation Duct (RED) experiment that took place off Oahu, Hawaii in 2001. The main finding is that aerosol size distributions can be represented by a superposition of the mean size distribution and the first eigenvector multiplied by an amplitude function. For the two aerosol data sets the mean size distribution is very similar in the range of small particles sizes (radius < 1μm) but the main difference appears for larger aerosols (radius > 1μm). It is also reflected by the spectral shape of the eigenvector. The differences can be related to the type of aerosols present at both locations, and the amplitude function can be associated to meteorological conditions. The amplitude function also indicates the episodes with the maximum/minimum continental influence. The results of this analysis will be used in upgrades of the ANAM model.

  1. Online Aerosol Size and Composition Measurements in Coastal Antarctica

    NASA Astrophysics Data System (ADS)

    DeCarlo, P. F.; Giordano, M.; Kalnajs, L.; Johnson, A.; Davis, S. M.; Deshler, T.; Toohey, D. W.

    2014-12-01

    Aerosol particles play a critical role in the chemical and radiative balance of the Antarctic atmosphere. Aerosols are both a source and sink of gas phase constituents, as well as a transport mechanism for oceanic chemical species into the continental interior. The interaction between aerosols, the gas phase, sea ice and the snow pack is complex and not well understood. Recent observations of ozone depletion events coupled with submicron aerosol mass increase highlight the interaction between the gas and particle phases. These interactions can lead to aerosol formation as well as the deposition of trace elements to the snow pack. To determine the composition and source regions of aerosols in the coastal Antarctic atmosphere, a suite of instruments was deployed in the 2014 Antarctic measurement season including a High Resolution Aerodyne Aerosol Mass Spectrometer (HR-AMS), Ultra High Sensitivity Aerosol Spectrometer (UHSAS), Ozone analyzer, Scanning Electrical Mobility Sizer (SEMS), and Particle-into-Liquid Sampler (PILS). Measurements of gas phase constituents and aerosol composition were interpreted in the context of back trajectories and local meteorological conditions to link the measured air masses to their source regions.

  2. Measurements of Aerosol Charge and Size Distribution for Graphite, Gold, Palladium, and Silver Nanoparticles

    SciTech Connect

    Simones, Matthew P.; Gutti, Veera R.; Meyer, Ryan M.; Loyalka, Sudarshan K.

    2011-11-01

    The role of charge on aerosol evolution and hence the nuclear source term has been an issue of interest, and there is a need for both experimental techniques and modeling for quantifying this role. Our focus here is on further exploration of a tandem differential mobility analyzer (TDMA) technique to simultaneously measure both the size and charge (positive, negative and neutral) dependent aerosol distributions. We have generated graphite, gold, silver, and palladium nanoparticles (aerosol) using a spark generator. We measure the electrical mobility-size distributions for these aerosols using a TDMA, and from these data we deduce the full charge-size distributions. We observe asymmetry in the particle size distributions for negative and positive charges. This asymmetry could have a bearing on the dynamics of charged aerosols, indicating that the assumption of symmetry for size distributions of negatively and positively charged particles in source term simulations may not be always appropriate. Also, the experimental technique should find applications in measurements of aerosol rate processes that are affected by both particle charge and size (e.g. coagulation, deposition, resuspension), and hence in modeling and simulation of the nuclear source term.

  3. Models of size spectrum of tropospheric aerosol

    NASA Astrophysics Data System (ADS)

    Tammet, H.

    Quality criteria of a model distribution are considered. Information losses due to the nonorthogonality of the spectrum parameter transformation are discussed. Models are compared with a view to approximation accuracy and losses of information. Smerkalov's average tropospheric aerosol spectrum and 271 observed spectra have been used for test. Highest accuracy and lowest losses of information were yielded by a distribution having power asymptotes on both the left and the right sides.

  4. Effect of Aerosol Size and Hygroscopicity on Aerosol Optical Depth in the Southeastern United States

    NASA Astrophysics Data System (ADS)

    Brock, Charles; Wagner, Nick; Gordon, Timothy

    2016-04-01

    Aerosol optical depth (AOD) is affected by the size, optical characteristics, and hygroscopicity of particles, confounding attempts to link remote sensing observations of AOD to measured or modeled aerosol mass concentrations. In situ airborne observations of aerosol optical, chemical, microphysical and hygroscopic properties were made in the southeastern United States in the daytime in summer 2013. We use these observations to constrain a simple model that is used to test the sensitivity of AOD to the various measured parameters. As expected, the AOD was found to be most sensitive to aerosol mass concentration and to aerosol water content, which is controlled by aerosol hygroscopicity and the ambient relative humidity. However, AOD was also fairly sensitive to the mean particle diameter and the width of the size distribution. These parameters are often prescribed in global models that use simplified modal parameterizations to describe the aerosol, suggesting that the values chosen could substantially bias the calculated relationship between aerosol mass and optical extinction, AOD, and radiative forcing.

  5. SAGE II aerosol data validation based on retrieved aerosol model size distribution from SAGE II aerosol measurements.

    PubMed

    Wang, P H; McCormick, M P; McMaster, L R; Chu, W P; Swissler, T J; Osborn, M T; Russell, P B; Oberbeck, V R; Livingston, J; Rosen, J M; Hofmann, D J; Grams, G W; Fuller, W H; Yue, G K

    1989-06-20

    This paper describes an investigation of the comprehensive aerosol correlative measurement experiments conducted between November 1984 and July 1986 for satellite measurement program of the Stratospheric Aerosol and Gas Experiment (SAGE II). The correlative sensors involved in the experiments consist of the NASA Ames Research Center impactor/laser probe, the University of Wyoming dustsonde, and the NASA Langley Research Center airborne 14-inch (36 cm) lidar system. The approach of the analysis is to compare the primary aerosol quantities measured by the ground-based instruments with the calculated ones based on the aerosol size distributions retrieved from the SAGE II aerosol extinction measurements. The analysis shows that the aerosol size distributions derived from the SAGE II observations agree qualitatively with the in situ measurements made by the impactor/laser probe. The SAGE II-derived vertical distributions of the ratio N0.15/N0.25 (where Nr is the cumulative aerosol concentration for particle radii greater than r, in micrometers) and the aerosol backscatter profiles at 0.532- and 0.6943-micrometer lidar wavelengths are shown to agree with the dustsonde and the 14-inch (36-cm) lidar observations, with the differences being within the respective uncertainties of the SAGE II and the other instruments. PMID:11539801

  6. Aerodynamic size associations of natural radioactivity with ambient aerosols

    SciTech Connect

    Bondietti, E.A.; Papastefanou, C.; Rangarajan, C.

    1986-04-01

    The aerodynamic size of /sup 214/Pb, /sup 212/Pb, /sup 210/Pb, /sup 7/Be, /sup 32/P, /sup 35/S (as SO/sub 4//sup 2 -/), and stable SO/sub 4//sup 2 -/ was measured using cascade impactors. The activity distribution of /sup 212/Pb and /sup 214/Pb, measured by alpha spectroscopy, was largely associated with aerosols smaller than 0.52 ..mu..m. Based on 46 measurements, the activity median aerodynamic diameter of /sup 212/Pb averaged 0.13 ..mu..m (sigma/sub g/ = 2.97), while /sup 214/Pb averaged 0.16 ..mu..m (sigma/sub g/ = 2.86). The larger median size of /sup 214/Pb was attributed to ..cap alpha..-recoil depletion of smaller aerosols following decay of aerosol-associated /sup 218/Po. Subsequent /sup 214/Pb condensation on all aerosols effectively enriches larger aerosols. /sup 212/Pb does not undergo this recoil-driven redistribution. Low-pressure impactor measurements indicated that the mass median aerodynamic diameter of SO/sub 4//sup 2 -/ was about three times larger than the activity median diameter /sup 212/Pb, reflecting differences in atmospheric residence times as well as the differences in surface area and volume distributions of the atmospheric aerosol. Cosmogenic radionuclides, especially /sup 7/Be, were associated with smaller aerosols than SO/sub 4//sup 2 -/ regardless of season, while /sup 210/Pb distributions in summer measurements were similar to sulfate but smaller in winter measurements. Even considering recoil following /sup 214/Po ..cap alpha..-decay, the avervage /sup 210/Pb labeled aerosol grows by about a factor of two during its atmospheric lifetime. The presence of 5 to 10% of the /sup 7/Be on aerosols greater than 1 ..mu..m was indicative of post-condensation growth, probably either in the upper atmosphere or after mixing into the boundary layer.

  7. The Angstrom Exponent and Bimodal Aerosol Size Distributions

    NASA Technical Reports Server (NTRS)

    Schuster, Gregory L.; Dubovik, Oleg; Holben, Brent H.

    2005-01-01

    Powerlaws have long been used to describe the spectral dependence of aerosol extinction, and the wavelength exponent of the aerosol extinction powerlaw is commonly referred to as the Angstrom exponent. The Angstrom exponent is often used as a qualitative indicator of aerosol particle size, with values greater than two indicating small particles associated with combustion byproducts, and values less than one indicating large particles like sea salt and dust. In this study, we investigate the relationship between the Angstrom exponent and the mode parameters of bimodal aerosol size distributions using Mie theory calculations and Aerosol Robotic Network (AERONET) retrievals. We find that Angstrom exponents based upon seven wavelengths (0.34, 0.38, 0.44, 0.5, 0.67, 0.87, and 1.02 micrometers) are sensitive to the volume fraction of aerosols with radii less then 0.6 micrometers, but not to the fine mode effective radius. The Angstrom exponent is also known to vary with wavelength, which is commonly referred to as curvature; we show how the spectral curvature can provide additional information about aerosol size distributions for intermediate values of the Angstrom exponent. Curvature also has a significant effect on the conclusions that can be drawn about two-wavelength Angstrom exponents; long wavelengths (0.67, 0.87 micrometers) are sensitive to fine mode volume fraction of aerosols but not fine mode effective radius, while short wavelengths (0.38, 0.44 micrometers) are sensitive to the fine mode effective radius but not the fine mode volume fraction.

  8. Metrological assessment of a portable analyzer for monitoring the particle size distribution of ultrafine particles.

    PubMed

    Stabile, Luca; Cauda, Emanuele; Marini, Sara; Buonanno, Giorgio

    2014-08-01

    Adverse health effects caused by worker exposure to ultrafine particles have been detected in recent years. The scientific community focuses on the assessment of ultrafine aerosols in different microenvironments in order to determine the related worker exposure/dose levels. To this end, particle size distribution measurements have to be taken along with total particle number concentrations. The latter are obtainable through hand-held monitors. A portable particle size distribution analyzer (Nanoscan SMPS 3910, TSI Inc.) was recently commercialized, but so far no metrological assessment has been performed to characterize its performance with respect to well-established laboratory-based instruments such as the scanning mobility particle sizer (SMPS) spectrometer. The present paper compares the aerosol monitoring capability of the Nanoscan SMPS to the laboratory SMPS in order to evaluate whether the Nanoscan SMPS is suitable for field experiments designed to characterize particle exposure in different microenvironments. Tests were performed both in a Marple calm air chamber, where fresh diesel particulate matter and atomized dioctyl phthalate particles were monitored, and in microenvironments, where outdoor, urban, indoor aged, and indoor fresh aerosols were measured. Results show that the Nanoscan SMPS is able to properly measure the particle size distribution for each type of aerosol investigated, but it overestimates the total particle number concentration in the case of fresh aerosols. In particular, the test performed in the Marple chamber showed total concentrations up to twice those measured by the laboratory SMPS-likely because of the inability of the Nanoscan SMPS unipolar charger to properly charge aerosols made up of aggregated particles. Based on these findings, when field test exposure studies are conducted, the Nanoscan SMPS should be used in tandem with a condensation particle counter in order to verify and correct the particle size distribution data

  9. Drop size measurement of liquid aerosols

    NASA Astrophysics Data System (ADS)

    Liu, B. Y. H.; Pui, D. Y. H.; Xian-Qing, Wang

    The factor B = D/ D' relating the diameter D of a spherical liquid drop to the diameter, D˜, of the same drop collected on a microscope slide has been measured for DOP (di-octyl phthalate) and oleic acid aerosols. The microscope slide was coated with a fluorocarbon, oleophobic surfactant (L-1428, 3M Co., St. Paul, MN). The ratio was found to be independent of drop diameter in the 2-50 μm range and the mean value of B was found to be 0.700 for oleic acid and 0.690 for DOP. Similar measurements for oleic acid and DOP drops collected on a clean, uncoated slide resulted in the values of 0.419 and 0.303, respectively. The experimental values of B were compared with the theoretical values based on contact angle measurements. Good agreement was obtained.

  10. Middle East measurements of concentration and size distribution of aerosol particles for coastal zones

    NASA Astrophysics Data System (ADS)

    Bendersky, Sergey; Kopeika, Norman S.; Blaunstein, Natan S.

    2005-10-01

    Recently, an extension of the Navy Aerosol Model (NAM) was proposed based on analysis of an extensive series of measurements at the Irish Atlantic Coast and at the French Mediterranean Coast. We confirm the relevance of that work for the distant eastern Meditteranean and extend several coefficients of that coastal model, proposed by Piazzola et al. for the Meditteranean Coast (a form of the Navy Aerosol Model), to midland Middle East coastal environments. This analysis is based on data collected at three different Middle East coastal areas: the Negev Desert (Eilat) Red Sea Coast, the Sea of Galilee (Tiberias) Coast, and the Mediterranean (Haifa) Coast. Aerosol size distributions are compared with those obtained through measurements carried out over the Atlantic, Pacific, and Indian Ocean Coasts, and Mediterranean, and Baltic Seas Coasts. An analysis of these different results allows better understanding of the similarities and differences between different coastal lake, sea, and open ocean zones. It is shown that in the coastal regions in Israel, compared to open ocean and other sea zones, larger differences in aerosol particle concentration are observed. The aerosol particle concentrations and their dependences on wind speed for these coastal zones are analyzed and discussed. We propose to classify the aerosol distribution models to either: 1. a coastal model with marine aerosol domination; 2. a coastal model with continental aerosol domination (referred to as midland coast in this work); or 3. a coastal model with balanced marine and continental conditions.

  11. Three optical methods for remotely measuring aerosol size distributions.

    NASA Technical Reports Server (NTRS)

    Reagan, J. A.; Herman, B. M.

    1971-01-01

    Three optical probing methods for remotely measuring atmospheric aerosol size distributions are discussed and contrasted. The particular detection methods which are considered make use of monostatic lidar (laser radar), bistatic lidar, and solar radiometer sensing techniques. The theory of each of these measurement techniques is discussed briefly, and the necessary constraints which must be applied to obtain aerosol size distribution information from such measurements are pointed out. Theoretical and/or experimental results are also presented which demonstrate the utility of the three proposed probing methods.

  12. Endotoxin in Size-Separated Metal Working Fluid Aerosol Particles.

    PubMed

    Dahlman-Höglund, Anna; Lindgren, Åsa; Mattsby-Baltzer, Inger

    2016-08-01

    Patients with airway symptoms working in metal working industries are increasing, despite efforts to improve the environmental air surrounding the machines. Our aim was to analyse the amount of endotoxin in size-separated airborne particles of metal working fluid (MWF) aerosol, by using the personal sampler Sioutas cascade impactor, to compare filter types, and to compare the concentration of airborne endotoxin to that of the corresponding MWFs. In a pilot field study, aerosols were collected in two separate machine halls on totally 10 occasions, using glass fibre and polytetrafluoroethylene (PTFE) filters in parallel at each station. Airborne endotoxin was distributed over all size fractions. While a major part was found in the largest size fraction (72%, 2.5-10 µm), up to 8% of the airborne endotoxin was detected in the smallest size fraction (<0.25 µm). Comparing the efficiency of the filter types, a significantly higher median endotoxin level was found with glass fibres filters collecting the largest particle-size fraction (1.2-fold) and with PTFE filters collecting the smallest ones (5-fold). The levels of endotoxin in the size-separated airborne particle fractions correlated to those of the MWFs supporting the aerosol-generating machines. Our study indicates that a significant part of inhalable aerosols of MWFs consists of endotoxin-containing particles below the size of intact bacteria, and thus small enough to readily reach the deepest part of the lung. Combined with other chemical irritants of the MWF, exposure to MWF aerosols containing endotoxin pose a risk to respiratory health problems. PMID:27268595

  13. Shock-induced behavior in micron-sized water aerosols

    NASA Astrophysics Data System (ADS)

    Hanson, Thomas C.; Davidson, David F.; Hanson, Ronald K.

    2007-05-01

    We have developed a suite of tools for studying aerosols behind shock waves. A Mie-extinction particle sizing diagnostic and a computational model, along with a specially designed square-section shock tube were developed to study the time-history of micrometer-sized aerosols behind shock waves. These tools are critically needed to pursue the use of shock tubes to study the combustion behavior of low-vapor-pressure fuels. While the facility is designed to study reactive systems, we began by measuring the behavior of water aerosols in the range of 1-10μm behind shock waves with temperatures between 450 and 600K and pressures between 0.64 and 1.1atm. From these data we determined evaporation rates and found a correlation that provides the noncontinuum evaporation rate in terms of the d2 evaporation rate and a correction function.

  14. Aircraft studies of size-dependent aerosol sampling through inlets

    NASA Technical Reports Server (NTRS)

    Porter, J. N.; Clarke, A. D.; Ferry, G.; Pueschel, R. F.

    1992-01-01

    Representative measurement of aerosol from aircraft-aspirated systems requires special efforts in order to maintain near isokinetic sampling conditions, estimate aerosol losses in the sample system, and obtain a measurement of sufficient duration to be statistically significant for all sizes of interest. This last point is especially critical for aircraft measurements which typically require fast response times while sampling in clean remote regions. This paper presents size-resolved tests, intercomparisons, and analysis of aerosol inlet performance as determined by a custom laser optical particle counter. Measurements discussed here took place during the Global Backscatter Experiment (1988-1989) and the Central Pacific Atmospheric Chemistry Experiment (1988). System configurations are discussed including (1) nozzle design and performance, (2) system transmission efficiency, (3) nonadiabatic effects in the sample line and its effect on the sample-line relative humidity, and (4) the use and calibration of a virtual impactor.

  15. Size segregated water uptake of the urban submicrometer aerosol in Beijing

    NASA Astrophysics Data System (ADS)

    Massling, A.; Stock, M.; Wehner, B.; Wu, Z. J.; Hu, M.; Brüggemann, E.; Gnauk, T.; Herrmann, H.; Wiedensohler, A.

    Physical and chemical properties of submicrometer aerosol particles were measured in summer 2004 (June/July) and winter 2005 (January/February) in Beijing, Peoples Republic of China, using a Twin-Differential Mobility Particle Sizer (T-DMPS), a Hygroscopicity-Tandem Differential Mobility Analyzer (H-TDMA), and a Micro Orifice Uniform Deposit Impactor (MOUDI). Particle number-size distributions were measured in the diameter range Dp = 3-800 nm and hygroscopic properties were determined at initial dry particle diameters of Dp j ( j = 30, 50, 80, 150, 250, and 350 nm) at a relative humidity (RH) of 90%. Hygroscopic properties were compared with chemical analyses of aerosol samples taken with the MOUDI. Based on the hygroscopicity data, the total hygroscopic particle volume was modeled, including dependence on dry particle size, season and level of pollution using a simple approach. Overall, the chemical analysis showed ammonium sulfate to be the major inorganic component of the urban submicrometer aerosol in Beijing along with relatively high fractions of elemental carbon (10-25%) and organic matter (15-60%) depending on particle size and season. The hygroscopic growth distributions (H-TDMA) subdivided the aerosol population into three different groups of particles with varying growth factors depending on dry particle size, namely nearly hydrophobic (growth factor = 0.96-1.07), less hygroscopic (1.06-1.29) and more hygroscopic (1.26-1.62). Hydrophobic particle fractions indicating freshly emitted soot/carbonaceous particles varied between 10 and 32% depending on dry particle size and season. During heavily polluted times, a decreasing number of hydrophobic particle fractions indicated that the urban submicrometer aerosol in Beijing was highly influenced by more aged aerosol transported from the industrial regions around Beijing containing sulfate as a major component. Based on model calculations, the urban submicrometer aerosol in Beijing showed strong compositional

  16. PARTICLE SIZE DISTRIBUTIONS FOR AN OFFICE AEROSOL

    EPA Science Inventory

    The article discusses an evaluation of the effect of percent outdoor air supplied and occupation level on the particle size distributions and mass concentrations for a typical office building. (NOTE: As attention has become focused on indoor air pollution control, it has become i...

  17. Development of PIXE, PESA and Transmission Ion Microscopy Capability to Measure Aerosols by Size and Time

    SciTech Connect

    Shutthanandan, Shuttha ); Thevuthasan, Theva ); Disselkamp, Robert S. ); Stroud, Ashley M.; Cavanagh, Andrew S.; Adams, Evan M.; Baer, Donald R. ); Barrie, Leonard A. ); Cliff, Steven S.; Jimenez-Cruz, M; Cahill, Thomas A.

    2002-01-01

    The elemental analysis of aerosol composition with high time and spatial resolution is crucial in the studies related to environmental issues such as human health, urban smog formation, regional visibility, and climate change. The effects of atmospheric aerosols are closely related to their size distribution, which plays a major role in understanding transport and removal processes and in pinpointing possible aerosol sources. Hence, there is a need for simultaneous measurements of compositions and particle size distribution of aerosols. We have developed a capability that consists of a combination of PIXE, PESA and STIM (same location on the sample) at the accelerator facility in Environmental Molecular Sciences Laboratory (EMSL) to address some of the needs associated with time series and size distribution. Simultaneous measurements of PIXE and PESA can be performed on aerosols collected using 3 stage improved rotating drum impactor by size (3 modes, 2.5 to 0.07 um) and time (2 mm rotation for every 8 hours) on a 20 cm long Teflon strips with a time resolution of 2 hours (using 500 micron size proton beam). Two Teflon strips can be mounted on the manipulator at the same time without breaking the vacuum through a load-lock. Movable and fixed surface barrier detectors are used for PESA and STIM measurements respectively. Preliminary measurements were carried out using the aerosol samples collected at the 62nd floor of Williams Tower in Houston, Texas. These aerosol samples were also analyzed by synchrotron x-ray microprobe (S-XRF) at Advanced Light Source (ALS) and the comparison of XRF and ion beam results along with the details of the capability will be discussed.

  18. Some Algorithms For Simulating Size-resolved Aerosol Dynamics Models

    NASA Astrophysics Data System (ADS)

    Debry, E.; Sportisse, B.

    The objective of this presentation is to show some algorithms used to solve aerosol dynamics in 3D dispersion models. INTRODUCTION The gas phase pollution has been widely studied and some models are now available . The situation is quite different with respect to atmospheric aerosols . However at- mospheric particulate matter significantly influences atmospheric properties such as radiative balance, cloud formation, gas pollutants concentrations ( gas to particle con- version ), and has an impact on man health. As aerosols properties ( optical, hygroscopic, noxiousness ) depend mainly on their size, it appears important to be able to follow the aerosol ( or particle ) size distribution (PSD) during time. This former is modified by physical processes as coagulation, condensation or evaporation, nucleation and removal. Aerosol dynamics is usually modelized by the well-known General Dynamics Equation (GDE) [1]. MODELS Several models already exist to solve this equation. Multi-modal models are widely used [2] [3] because of the few parameters needed, but the GDE is solved only on its moments and the PSD is assumed to remain in a log-normal form. On the contrary, size-resolved models implies a discretization of the aerosol size spec- trum into several bins and to solve the GDE within each one. This step can be per- formed either by resolving each process separately ( splitting ), for example coagula- tion can be resolved by the well-known "size-binning" algorithms [4] and condensa- tion leads to an advection equation on the PSD [5], or by coupling all processes, what the finite elements [6] and stochastic methods [7] allows. Stochastic algorithms may not be competitive compared to deterministic ones with respect to the computation time, but they provide reference solutions useful to validate more operational codes on realistic cases, as analytic solutions of the GDE exist only for academic cases. REFERENCES [1] Seinfeld, J.H. and Pandis,S.N. Atmospheric chemistry and

  19. Variations in Aerosol Size and Number during Discover-Aq

    NASA Astrophysics Data System (ADS)

    Winstead, E.; Thornhill, K. L.; Beyersdorf, A. J.; Hudgins, C.; Ziemba, L. D.; Anderson, B. E.

    2011-12-01

    The Deriving Information on Surface Conditions from Column and Vertically Resolved Observations Relevant to Air Quality (DISCOVER-AQ) mission is a multi-year campaign designed to improve the use of satellites to monitor surface-level air quality. DISCOVER-AQ is addressing its goals by conducting a series of coordinated ground-based and flight experiments over urban areas with well-established air quality issues to obtain vertically resolved measurements of trace gas and aerosol components for comparing with satellite observations of column-integrated quantities. The first flight mission was conducted over the Washington D.C. - Baltimore metropolitan area during July, 2011. It consisted of 14 science flights by the NASA Wallops Flight Facility P-3B aircraft over 6 highly-instrumented ground sites located around Baltimore. This region frequently violates ambient air quality standards for particulate matter as well as ozone and has a complex mixture of biogenic and anthropogenic sources. A large suite of aerosol instruments were flown onboard the P-3B aircraft to measure the microphysical, optical and chemical properties of aerosols during spirals over the ground sites and during low level flights over Interstates 95 and 695 connecting Washington and Baltimore. The package included condensation nuclei (CN) counters to provide measurements of total aerosols greater than 3 nm (UCN) and 10 nm (CN); a scanning mobility particle sizer (SMPS) to measure size in the 10 to 300 nm diameter range; an Ultra High Sensitivity Aerosol Spectrometer (UHSAS) for sizing 90 to 1000 nm diameter particles, and a Laser Aerosol Spectrometer for sizing 100 to 7500 nm particles. This presentation examines the variability of aerosol size and number in both time and space over the Baltimore metropolitan region. Within the atmospheric boundary layer between 0.3 and 1 km, particle number densities and size distributions varied considerable over short time periods and across horizontal distances

  20. Inference of stratospheric aerosol composition and size distribution from SAGE II satellite measurements

    NASA Technical Reports Server (NTRS)

    Wang, Pi-Huan; Mccormick, M. P.; Fuller, W. H.; Yue, G. K.; Swissler, T. J.; Osborn, M. T.

    1989-01-01

    A method for inferring stratospheric aerosol composition and size distribution from the water vapor concentration and aerosol extinction measurements obtained in the Stratospheric Aerosol and Gas Experiment (SAGE) II and the associated temperature from the NMC. The aerosols are assumed to be sulfuric acid-water droplets. A modified Levenberg-Marquardt algorithm is used to determine model size distribution parameters based on the SAGE II multiwavelength aerosol extinctions. It is found that the best aerosol size information is contained in the aerosol radius range between about 0.25 and 0.80 micron.

  1. [Bronchodilator aerosol propellant interferes with an photoacoustic spectrophotometer respiratory gas analyzer].

    PubMed

    Makino, A; Morimoto, Y; Matsumoto, S; Oka, H; Shimizu, K; Miyauchi, Y

    1998-05-01

    A patient with bronchial asthma was scheduled for an operation under nitrous oxide-isoflurane anesthesia. We monitored isoflurane concentrations continuously using an anesthetic gas analyzer (BK 1304). Upon puffing procaterol hydrochloride aerosol for 4 times, the analyzer showed a rapid increase in end-tidal isoflurane concentration. The BK 1304 uses infrared photoacoustic spectrophotometry and it is susceptible to interferences caused by Freon propellants in bronchodilator aerosols. We should take care in monitoring inhalational anesthetics when using aerosols containing Freon propellants. PMID:9621676

  2. Chemical Composition and Size Distributions of Coastal Aerosols Observed on the U.S. East Coast

    NASA Astrophysics Data System (ADS)

    Xia, L.; Song, F.; Jusino-Atresino, R.; Thuman, C.; Gao, Y.

    2008-12-01

    Aerosol input is an important source of certain limiting nutrients, such as iron, for phytoplankton growth in several large oceanic regions. As the efficiency of biological uptake of nutrients may depend on the aerosol properties, a better knowledge of aerosol properties is critically important. Characterizing aerosols over the coastal ocean needs special attention, because the properties of aerosols could be altered by many anthropogenic processes in this land-ocean transition zone before they are transported over the remote ocean. The goal of this experiment was to examine aerosol properties, in particular chemical composition, particle-size distributions and iron solubility, over the US Eastern Seaboard, an important boundary for the transport of continental substances from North America to the North Atlantic Ocean. Our field sampling site was located at Tuckerton (39°N, 74°W) on the southern New Jersey coast. Fourteen sets of High-Volume aerosol samples and three sets of size segregated aerosol samples by a 10-stage MOUDI impactor were collected during 2007 and 2008. The ICP-MS methodology was used to analyze aerosol samples for the concentrations of thirteen trace elements: Al, Fe, Mn, Sc, Cd, Pb, Sb, Ni, Co, Cr, Cu, Zn and V. The IC procedures were applied to determine five cations (sodium, ammonium, potassium, magnesium and calcium) and eleven anions (fluoride, acetate, propionate, formate, MSA, chloride, nitrate, succinate, malonate, sulfate and oxalate). The UV spectrometry was employed for the determination of iron solubility. Preliminary results suggest three major sources of aerosols: anthropogenic, crustal and marine. At this location, the concentrations of iron (II) ranged from 2.8 to 29ng m-3, accounting for ~20% of the total iron. The iron concentrations at this coastal site were substantially lower than those observed in Newark, an urban site in northern NJ. High concentrations of iron (II) were associated with both fine and coarse aerosol

  3. The Effect of Particle Size on Iron Solubility in Atmospheric Aerosols

    NASA Astrophysics Data System (ADS)

    Marcotte, A. R.; Majestic, B. J.; Anbar, A. D.; Herckes, P.

    2012-12-01

    The long range transport of mineral dust aerosols, which contain approximately 3% iron by mass, results in an estimated 14-16 Tg of iron deposited into the oceans annually; however, only a small percentage of the deposited iron is soluble. In high-nutrient, low chlorophyll ocean regions iron solubility may limit phytoplankton primary productivity. Although the atmospheric transport processes of mineral dust aerosols have been well studied, the role of particle size has been given little attention. In this work, the effect of particle size on iron solubility in atmospheric aerosols is examined. Iron-containing minerals (illite, kaolinite, magnetite, goethite, red hematite, black hematite, and quartz) were separated into five size fractions (10-2.5, 2.5-1, 1-0.5, 0.5-0.25, and <0.25μm) and extracted into buffer solutions simulating environments in the transport of aerosol particles for 150 minutes. Particle size was confirmed by scanning electron microscopy (SEM). Soluble iron content of the extracted mineral solutions was determined by inductively coupled plasma-mass spectrometry (ICP-MS). Extracted mineral solutions were also analyzed for Fe(II) and Fe(III) content using a ferrozine/UV-VIS method. Preliminary results show that differences in solution composition are more important than differences in size. When extracted into acetate and cloudwater buffers (pH 4.25-4.3), < 0.3% of the Fe in iron oxides (hematite, magnetite, and goethite) is transferred to solution as compared to ~0.1-35% for clays (kaolinite and illite). When extracted into a marine aerosol solution (pH 1.7), the percentage of Fe of the iron oxides and clays transferred to solution increases to approximately 0.5-3% and 5-70%, respectively. However, there is a trend of increased %Fe in the minerals transferred to solution in the largest and smallest size fractions (~0.01-0.3% and ~0.5-35% for iron oxides and clays, respectively), and decreased %Fe in the minerals transferred to solution in the mid

  4. Aged boreal biomass burning aerosol size distributions from BORTAS 2011

    NASA Astrophysics Data System (ADS)

    Sakamoto, K. M.; Allan, J. D.; Coe, H.; Taylor, J. W.; Duck, T. J.; Pierce, J. R.

    2014-09-01

    Biomass-burning aerosols contribute to aerosol radiative forcing on the climate system. The magnitude of this effect is partially determined by aerosol size distributions, which are functions of source fire characteristics (e.g. fuel type, MCE) and in-plume microphysical processing. The uncertainties in biomass-burning emission number size-distributions in climate model inventories lead to uncertainties in the CCN concentrations and forcing estimates derived from these models. The BORTAS-B measurement campaign was designed to sample boreal biomass-burning outflow over Eastern Canada in the summer of 2011. Using these BORTAS-B data, we implement plume criteria to isolate the characteristic size-distribution of aged biomass-burning emissions (aged ∼1-2 days) from boreal wildfires in Northwestern Ontario. The composite median size-distribution yields a single dominant accumulation mode with Dpm = 230 nm (number-median diameter), σ = 1.7, which are comparable to literature values of other aged plumes of a similar type. The organic aerosol enhancement ratios (ΔOA / ΔCO) along the path of Flight b622 show values of 0.05-0.18 μg m-3 ppbv-1 with no significant trend with distance from the source. This lack of enhancement ratio increase/decrease with distance suggests no detectable net OA production/evaporation within the aged plume over the sampling period. A Lagrangian microphysical model was used to determine an estimate of the freshly emitted size distribution corresponding to the BORTAS-B aged size-distributions. The model was restricted to coagulation and dilution processes based on the insignificant net OA production/evaporation derived from the ΔOA / ΔCO enhancement ratios. We estimate that the fresh-plume median diameter was in the range of 59-94 nm with modal widths in the range of 1.7-2.8 (the ranges are due to uncertainty in the entrainment rate). Thus, the size of the freshly emitted particles is relatively unconstrained due to the uncertainties in

  5. Concentrations and size distributions of Antarctic stratospheric aerosols

    NASA Technical Reports Server (NTRS)

    Ferry, G. V.; Pueschel, R. F.; Neish, E.; Schultz, M.

    1989-01-01

    Particle Measuring Systems laser particle spectrometer (ASAS-X and FSSP) probes were used to measure aerosol particle concentrations and size distributions during 11 ER-2 flights between Punta Arenas (53 deg S) and Antarctica (up to 72 deg S) from August 17 to September 22, 1987. The time resolution was 10 s, corresponding to a spatial resolution of 2 km. The data were divided into two size classes (0.05-0.25 and 0.53-5.5 micron radius) to separate the small particle from the coarse particle populations. Results show that the small-particle concentrations are typical for a background aerosol during volcanic quiescence. This concentration is generally constant along a flight track; in only one instance a depletion of small particles during a polar stratospheric cloud (PSC) encounter was measured, suggesting a nucleation of type I PSC particles on background aerosols. Temporary increases of the coarse particle concentrations indicated the presence of tenuous polar stratospheric clouds that were encountered most frequently at the southernmost portion of a flight track and when the aircraft descended to lower altitudes. During 'particle events', particle modes were found at 0.6-micron radius, corresponding to type I PSCs, and occasionally, at 2.0-micron radius corresponding to type II PSCs.

  6. Particle size influences aerosol deposition in guinea pigs during bronchoconstriction

    SciTech Connect

    Praud, J.P.; Macquin-Mavier, I.; Wirquin, V.; Meignan, M.; Harf, A.

    1986-03-01

    The role of two factors determining the deposition of aerosols in the respiratory tract was investigated: the particle size and the nature of the airflow in the airways. An aerosol of Tc99 m-DTPA was generated, with a mass median aerodynamic diameter of either 3 ..mu..m (Bird nebulizer) or 0.5 ..mu..m (Jouan nebulizer). The vehicle was either saline (S) or histamine (H) at a concentration which was previously shown to induce a 50% decrease of specific airway conductance. Spontaneously breathing guinea pigs were exposed during 2 minutes to the aerosol, then killed and the radioactivity in the pharynx, the trachea, the large bronchi and the remaining parenchyma was measured. Results are evaluated as the percentage of total radioactivity in the respiratory tract (mean +/- SEM). Analysis of variance showed that there was a significant difference in the pattern of deposition for large particles (3 ..mu..m) during bronchoconstriction: the more proximal deposition can be ascribed to inertial impaction. Particle size should be clearly defined during histamine challenge in experimental animals.

  7. Surface Chemistry at Size-Selected Nano-Aerosol Particles

    NASA Astrophysics Data System (ADS)

    Roberts, Jeffrey

    2005-03-01

    A method has been developed to conduct surface chemistry and extract surface kinetic rates from size-selected aerosol nanoparticles. The measurements encompass broad ranges of particle size, phase, and composition. Results will be presented on the uptake of water by aerosolized soot nanoparticles of radius between 10 and 40 nm. Water uptake was monitored by tandem differential mobility analysis (T-DMA), which is capable of measuring changes in particle diameter as little as 0.2 nm. Soot particles were produced in an ethene diffusion flame and extracted into an atmospheric pressure aerosol flow tube reactor. The particles were subjected to various thermal and oxidative treatments, and the effects of these treatments on the ability of soot to adsorb monolayer quantities of water was determined. The results are important because soot nucleates atmospheric cloud particles. More generally, the results represent one of the first kinetic and mechanistic studies of gas-phase nanoparticle reactivity. Co-author: Henry Ajo, University of Minnesota

  8. Susceptibility of Tribolium confusum (Coleoptera: Tenebrionidae) to pyrethrin aerosol: effects of aerosol particle size, concentration, and exposure conditions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A series of laboratory studies were conducted to assess effect of droplet size on efficacy of pyrethrin aerosol against adults of Tribolium confusum Jacqueline DuVal, the confused flour beetle. A vertical flow aerosol exposure chamber that generated a standardized particle size diameter was used for...

  9. Mass size distributions of elemental aerosols in industrial area

    PubMed Central

    Moustafa, Mona; Mohamed, Amer; Ahmed, Abdel-Rahman; Nazmy, Hyam

    2014-01-01

    Outdoor aerosol particles were characterized in industrial area of Samalut city (El-minia/Egypt) using low pressure Berner cascade impactor as an aerosol sampler. The impactor operates at 1.7 m3/h flow rate. Seven elements were investigated including Ca, Ba, Fe, K, Cu, Mn and Pb using atomic absorption technique. The mean mass concentrations of the elements ranged from 0.42 ng/m3 (for Ba) to 89.62 ng/m3 (for Fe). The mass size distributions of the investigated elements were bi-modal log normal distribution corresponding to the accumulation and coarse modes. The enrichment factors of elements indicate that Ca, Ba, Fe, K, Cu and Mn are mainly emitted into the atmosphere from soil sources while Pb is mostly due to anthropogenic sources. PMID:26644919

  10. The vertical distribution of Martian aerosol particle size

    NASA Astrophysics Data System (ADS)

    Guzewich, Scott D.; Smith, Michael D.; Wolff, Michael J.

    2014-12-01

    Using approximately 410 limb-viewing observations from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM), we retrieve the vertical distribution of Martian dust and water ice aerosol particle sizes. We find that dust particles have an effective radius of 1.0 µm over much of the atmospheric column below 40 km throughout the Martian year. This includes the detached tropical dust layers detected in previous studies. Little to no variation with height is seen in dust particle size. Water ice clouds within the aphelion cloud belt exhibit a strong sorting of particle size with height, however, and the effective radii range from >3 µm below 20 km to near 1.0 µm at 40 km altitude. Conversely, water ice clouds in the seasonal polar hoods show a near-uniform particle size with an effective radius of approximately 1.5 µm throughout the atmospheric column.

  11. Seasonal Variability of the Black Carbon Size Distribution in the Atmospheric Aerosol

    NASA Astrophysics Data System (ADS)

    Kozlov, V. S.; Shmargunov, V. P.; Panchenko, M. V.; Chernov, D. G.; Kozlov, A. S.; Malyshkin, S. B.

    2016-04-01

    Round-the-clock measurements of the black carbon size distribution in the submicron near-ground aerosol of Western Siberia performed in 2014 by the diffusion method developed by the authors are analyzed. It is revealed that the tendency for decreasing the volume median diameter and the amplitude of distribution of the black carbon is traced in the seasonal dynamics of the average monthly black carbon particle size distribution (approximated by a single-mode lognormal function) during winter-to-summer season transition. The shape of the black carbon size distributions is in agreement with measurements by other well-known methods in different geographic regions.

  12. Aerosol Size Distribution Response to Anthropogenically Driven Historical Changes in Biogenic Secondary Organic Aerosol Formation

    NASA Astrophysics Data System (ADS)

    Pierce, J. R.; D'Andrea, S.; Acosta Navarro, J. C.; Farina, S.; Scott, C.; Farmer, D. K.; Spracklen, D. V.; Riipinen, I.

    2014-12-01

    Emissions of biological volatile organic compounds (BVOC) have changed in the past millennium due to changes in land use, temperature and CO2 concentrations. A recent model reconstruction of BVOC emissions over the past millennium predicted the changes in the three dominant secondary organic aerosol (SOA) producing BVOC classes (isoprene, monoterpenes and sesquiterpenes). The reconstruction predicted that in global averages isoprene emissions have decreased (land-use changes to crop/grazing land dominate the reduction), while monoterpene and sesquiterpene emissions have increased (temperature increases dominate the increases); however, all three show both increases and decreases in certain regions due to competition between the various influencing factors. These BVOC changes have largely been anthropogenic in nature, and land-use change was shown to have the most dramatic effect by decreasing isoprene emissions. We use these modeled estimates of these three dominant BVOC classes' emissions from the years 1000 to 2000 to test the effect of anthropogenic changes to BVOC emissions on SOA formation and global aerosol size distributions using the GEOS-Chem-TOMAS global aerosol microphysics model. With anthropogenic emissions (e.g. SO2, NOx, primary aerosols) held at present day values and BVOC emissions changed from year 1000 to year 2000 values, decreases in the number concentration of particles of size Dp > 80 nm (N80) of >25% in year 2000 relative to year 1000 were predicted in regions with extensive land-use changes since year 1000. This change in N80 was predominantly driven by a shift towards crop/grazing land that produces less BVOC than the natural vegetation. Similar sensitivities to year 1000 vs. year 2000 BVOC emissions exist when anthropogenic emissions are turned off. This large decrease in N80 could be a largely overlooked and important anthropogenic aerosol effect on regional climates.

  13. Deriving Vertical Profiles of Aerosol Sizes from TES

    NASA Astrophysics Data System (ADS)

    Wolff, M. J.; Clancy, R. T.; Smith, M. D.; McConnochie, T. H.; Flittner, D. E.; Fouchet, T.

    2011-12-01

    Vertical variations in aerosol particle sizes can have a dramatic effect in their net impact on the state and evolution of the Martian atmosphere. Recent analyses of data from the Spectroscopy for the Investigation of the Characteristics of the Atmosphere of Mars (SPICAM) and the Thermal Emission Spectrometer (TES) instruments offer some long overdue progress in constraining this aspect of aerosols. However, significantly more work remains to be done along these lines in order to better constrain and inform modern dynamical simulations of the Martian atmosphere. Thus, the primary goal of our work is to perform retrievals of particle size as a function of altitude for both dust and water ice aerosols. The choice of the TES dataset, with pole-to-pole coverage over a period of nearly three martian years, provides the crucial systematic temporal and spatial sampling. Additional leverage on the particle size will be obtained by using both solarband bolometry and infrared (IR) spectroscopy. Our presentation will include: 1) A summary of our limb radiative transfer comparison/validation exercises which include Monte Carlo, Gauss-Seidel, and discrete-ordinate algorithms (including the plane-parallel source function approximation). 2) The initial results of the application of our particle size retrieval scheme to the TES observations of the 2001 planet encircling dust event. 3) A few test applications to the Mars Climate Sounder (MCS) radiance profiles (enabled by the recent solarband radiometric calibration by Bandfield and collaborators). 4) Our plans for additional retrievals (aphelion cloud season, lower optical depth locations and seasons, etc.) and the distribution of the derived profiles.

  14. AEROSOL MEASUREMENTS IN THE SUBMICRON SIZE RANGE, STUDIES WITH AN AEROSOL CENTRIFUGE, A NEW DIFFUSION BATTERY, A LOW PRESSURE IMPACTOR AND AN ADVANCED CONDENSATION NUCLEI COUNTER

    EPA Science Inventory

    The report summarizes the investigations of four aerosol classifiers which cover finite, but overlapping ranges of the aerosol particle size spectrum. The first part is concerned with a cylindrical aerosol centrifuge, which measures aerodynamic equivalent diameters precisely. Thi...

  15. Comparison of spring and autumn time collected outdoor aerosol particles analyzed with depth-resolving SNMS

    NASA Astrophysics Data System (ADS)

    Goschnick, J.; Natzeck, C.; Sommer, M.

    1999-04-01

    Aerosol particles were collected in a size-classified way at the Forschungszentrum Karlsruhe during two autumn days of fine weather in September 1997 in order to analyze the depth distribution of the chemical inventory. The fine particles (<1 μm diameter) had a nitrogen- and sulfur-dominated shell with a thickness of 13 nm around a carbon core and mainly originate from traffic soot. The coarse particles (>1 μm diameter) consisted of soil dust or fly ash and sodium salt containing particles. Again the particle composition in greater depth was found to be different to the surface region, where nitrogen and sulfur as well as carbon were enriched. The surface-near nitrogen and sulfur could be attributed to ammonium sulfate, maybe deposited by particulate material formed from ammonia and SO x in the atmosphere. The results agree to a large degree with the analysis of outdoor particles collected at the same location but in spring time four years ago. However, the autumn particles of 1997 exhibited with 600 nm twice the diameter for the most frequent size compared to the particles sampled in spring of 1993.

  16. Size dependence of phase transitions in aerosol nanoparticles

    PubMed Central

    Cheng, Yafang; Su, Hang; Koop, Thomas; Mikhailov, Eugene; Pöschl, Ulrich

    2015-01-01

    Phase transitions of nanoparticles are of fundamental importance in atmospheric sciences, but current understanding is insufficient to explain observations at the nano-scale. In particular, discrepancies exist between observations and model predictions of deliquescence and efflorescence transitions and the hygroscopic growth of salt nanoparticles. Here we show that these discrepancies can be resolved by consideration of particle size effects with consistent thermodynamic data. We present a new method for the determination of water and solute activities and interfacial energies in highly supersaturated aqueous solution droplets (Differential Köhler Analysis). Our analysis reveals that particle size can strongly alter the characteristic concentration of phase separation in mixed systems, resembling the influence of temperature. Owing to similar effects, atmospheric secondary organic aerosol particles at room temperature are expected to be always liquid at diameters below ~20 nm. We thus propose and demonstrate that particle size should be included as an additional dimension in the equilibrium phase diagram of aerosol nanoparticles. PMID:25586967

  17. Measurements of aerosol particles in the size range 0.2-4.0 microns in the Antarctic

    NASA Astrophysics Data System (ADS)

    Leiterer, U.; Sakunov, G.

    The concentrations and size distributions of Antarctic Mie particles are investigated on the basis of (1) direct measurements of spectral optical thickness, (2) aerosol counts 1-2 m above the surface, and (3) studies of insoluble particles in ice cores. Data obtained at the Mirny, Vostok, and Molodezhnaia stations during the 1984-1985 polar summer are presented in tables and graphs and analyzed in detail. The high concentrations of aerosol particles in cores from the ice age are found to be consistent with a more turbid atmosphere during that period. The vertical profiles inferred from the current data are found to differ strongly from those observed at locations outside the Antarctic: the aerosol concentrations are extremely low near the surface of the polar plateau and increase with altitude. This phenomenon is attributed to a broad downward motion of aerosol-rich air from the stratosphere, supporting a model in which the stratosphere acts as a global background aerosol reservoir.

  18. Vertical profile and aerosol size distribution measurements in Iceland (LOAC)

    NASA Astrophysics Data System (ADS)

    Dagsson Waldhauserova, Pavla; Olafsson, Haraldur; Arnalds, Olafur; Renard, Jean-Baptiste; Vignelles, Damien; Verdier, Nicolas

    2014-05-01

    Cold climate and high latitudes regions contain important dust sources where dust is frequently emitted, foremost from glacially-derived sediments of riverbeds or ice-proximal areas (Arnalds, 2010; Bullard, 2013). Iceland is probably the most active dust source in the arctic/sub-arctic region (Dagsson-Waldhauserova, 2013). The frequency of days with suspended dust exceeds 34 dust days annually. Icelandic dust is of volcanic origin; it is very dark in colour and contains sharp-tipped shards with bubbles. Such properties allow even large particles to be easily transported long distances. Thus, there is a need to better understand the spatial and temporal variability of these dusts. Two launch campaigns of the Light Optical Aerosols Counter (LOAC) were conducted in Iceland with meteorological balloons. LOAC use a new optical design that allows to retrieve the size concentrations in 19 size classes between 0.2 and 100 microm, and to provide an estimate of the main nature of aerosols. Vertical stratification and aerosol composition of the subarctic atmosphere was studied in detail. The July 2011 launch represented clean non-dusty season with low winds while the November 2013 launch was conducted during the high winds after dusty period. For the winter flight (performed from Reykjavik), the nature of aerosols strongly changed with altitude. In particular, a thin layer of volcanic dust was observed at an altitude of 1 km. Further LOAC measurements are needed to understand the implication of Icelandic dust to the Arctic warming and climate change. A new campaign of LAOC launches is planned for May 2014. Reference: Arnalds, O., 2010. Dust sources and deposition of aeolian materials in Iceland. Icelandic Agricultural Sciences 23, 3-21. Bullard, J.E., 2013. Contemporary glacigenic inputs to the dust cycle. Earth Surface Processes and Landforms 38, 71-89. Dagsson-Waldhauserova, P., Arnalds O., Olafsson H. 2013. Long-term frequency and characteristics of dust storm events in

  19. Method for determining aerosol particle size device for determining aerosol particle size

    DOEpatents

    Novick, Vincent J.

    1998-01-01

    A method for determining the mass median diameter D of particles contained in a fluid is provided wherein the data of the mass of a pre-exposed and then a post-exposed filter is mathematically combined with data concerning the pressure differential across the same filter before and then after exposure to a particle-laden stream. A device for measuring particle size is also provided wherein the device utilizes the above-method for mathematically combining the easily quantifiable data.

  20. Phase Partitioning of Soluble Trace Gases with Size-Resolved Aerosols during the Nitrogen, Aerosol Composition, and Halogens on a Tall Tower (NACHTT) Campaign

    NASA Astrophysics Data System (ADS)

    Young, A.; Keene, W. C.; Pszenny, A.; Sander, R.; Maben, J. R.; Warrick-Wriston, C.; Bearekman, R.

    2011-12-01

    During February and March 2011, size-resolved and bulk aerosol were sampled at 22 m above the surface over nominal 12-hour (daytime and nighttime) intervals from the Boulder Atmospheric Observatory tower (40.05 N, 105.01 W, 1584-m elevation). Samples were analyzed for major organic and inorganic ionic constituents by high performance ion chromatography (IC). Soluble trace gases (HCl, HNO3, NH3, HCOOH, and CH3COOH) were sampled in parallel over 2-hour intervals with tandem mist chambers and analyzed on site by IC. NH4+, NO3-, and SO42- were the major ionic components of aerosols (median values of 57.7, 34.5, and 7.3 nmol m-3 at STP, respectively, N = 45) with 86%, 82%, and 82%, respectively, associated with sub-μm size fractions. Cl- and Na+ were present at significant concentrations (median values of 6.8 and 6.6 nmol m-3, respectively) but were associated primarily with super-μm size fractions (75% and 78%, respectively). Median values (and ranges) for HCl, HNO3, and NH3 were 21 (<20-1257), 120 (<45-1638), and 5259 (<1432-48,583) pptv, respectively. Liquid water contents of size-resolved aerosols and activity coefficients for major ionic constituents were calculated with the Extended Aerosol Inorganic Model II and IV (E-AIM) based on the measured aerosol composition, RH, temperature, and pressure. Size-resolved aerosol pHs were inferred from the measured phase partitioning of HCl, HNO3, and NH3. Major controls of phase partitioning and associated chemical dynamics will be presented.

  1. The inertial and electrical effects on aerosol sampling, charging, and size distribution

    SciTech Connect

    Wang, Chuenchung.

    1991-01-01

    An experimental study was conducted to investigate the effect of particle inertia on deposition behavior near the filter cassette sampler. Field sampling cassettes were tested in a subsonic wind tunnel for 0.2, 0.5 and 0.68 m/s wind speeds to simulate indoor air environment. Fluorescein aerosols of 2 and 5 {mu}m were generated from Berglund-Liu vibrating orifice generator as test material. Sampling tests were conducted in a subsonic wind tunnel with variables of particle size, wind speed, suction velocity and orientation of sampler examined to evaluate the combined effects. Sampling efficiencies were also examined. Electrostatic force is usually used as an effective method for removing, classifying and separating aerosols according to the electrical mobilities of the particulates. On the other hand, the aerosol charging theories possess differences in the ultrafine size range and need experimental verification. The present TSI's electrostatic aerosol analyzer has particle loss problem and cannot be used as a reliable tool in achieving efficient charging. A new unipolar charger with associated electronic circuits was designed, constructed and tested. The performance of the charger is tested in terms of particle loss, uncharged particles, and the collection efficiency of the precipitator. The results were compared with other investigator's data. The log-Beta distribution function is considered to be more versatile in representing size distribution. This study discussed the method in determining the size parameters under different conditions. Also the mutability of size distribution was evaluated when particles undergo coagulation or classification processes. Comparison of evolution between log-Beta and lognormal distributions were made.

  2. Aerosol size distribution estimation and associated uncertainty for measurement with a Scanning Mobility Particle Sizer (SMPS)

    NASA Astrophysics Data System (ADS)

    Coquelin, L.; Fischer, N.; Motzkus, C.; Mace, T.; Gensdarmes, F.; Le Brusquet, L.; Fleury, G.

    2013-04-01

    Scanning Mobility Particle Sizer (SMPS) is a high resolution nanoparticle sizing system that has long been hailed as the researcher's choice for airborne nanoparticle size characterization for nano applications including nanotechnology research and development. SMPS is widely used as the standard method to measure airborne particle size distributions below 1 μm. It is composed of two devices: a Differential Mobility Analyzer (DMA) selects particle sizes thanks to their electrical mobility and a Condensation Particle Counter (CPC) enlarges particles to make them detectable by common optical counters. System raw data represent the number of particles counted over several classes of mobility diameters. Then, common inversion procedures lead to the estimation of the aerosol size distribution. In this paper, we develop a methodology to compute the uncertainties associated with the estimation of the size distribution when several experiences have been carried out. The requirement to repeat the measure ensures a realistic variability on the simulated data to be generated. The work we present consists in considering both the uncertainties coming from the experimental dispersion and the uncertainties induced by the lack of knowledge on physical phenomena. Experimental dispersion is quantified with the experimental data while the lack of knowledge is modelled via the existing physical theories and the judgements of experts in the field of aerosol science. Thus, running Monte-Carlo simulations give an estimation of the size distribution and its corresponding confidence region.

  3. Method for determining aerosol particle size, device for determining aerosol particle size

    DOEpatents

    Novick, V.J.

    1998-10-06

    A method for determining the mass median diameter D of particles contained in a fluid is provided wherein the data of the mass of a pre-exposed and then a post-exposed filter is mathematically combined with data concerning the pressure differential across the same filter before and then after exposure to a particle-laden stream. A device for measuring particle size is also provided wherein the device utilizes the above-method for mathematically combining the easily quantifiable data. 2 figs.

  4. A diagnostic stratospheric aerosol size distribution inferred from SAGE II measurements

    NASA Technical Reports Server (NTRS)

    Thomason, Larry W.

    1991-01-01

    An aerosol size distribution model for the stratosphere is inferred based on 5 years of Stratospheric Aerosol and Gas Experiment (SAGE) II measurements of multispectral aerosol and water vapor extinction. The SAGE II aerosol and water vapor extinction data strongly suggest that there is a critical particle radius below which there is a relatively weak dependence of particle number density with size and above which there are few, if any, particles. A segmented power law model, as a simple representation of this dependence, is used in theoretical calculations and intercomparisons with a variety of aerosol measurements including dustsondes, longwave lidar, and wire impactors and shows a consistently good agreement.

  5. Fourier transform infrared spectroscopy of size-segregated aerosol deposits on foil substrates.

    PubMed

    Hopey, Judith A; Fuller, Kirk A; Krishnaswamy, Venkataramanan; Bowdle, David; Newchurch, Michael J

    2008-05-01

    A method based on Fourier transform infrared (FTIR) double-pass transmittance spectroscopy was developed for determining functional group loading in size-segregated ambient aerosol deposits. The impactor employed for sample collection utilized rotating stages, which produced uniform particulate matter (PM) deposits on standard Al foil substrates. Each sample was analyzed without extraction using an FTIR spectrometer equipped with a reflectometer accessory. The use of the reflectometer obviated the need for infrared window materials as substrates. (NH(4))(2)SO(4) aerosol generated under laboratory conditions were used to calibrate deposit mass to the band strength of the relatively isolated nu(4) bending mode of SO(2-)(4) centered near 620 cm(-1). Atmospheric PM was sampled during the summer of 2004 in Huntsville, Ala. Sulfate concentrations determined in this initial study correlated well with measurements made by collocated EPA air samplers. PMID:18449290

  6. Size-Resolved Volatility and Chemical Composition of Aged European Aerosol Measured During FAME-2008

    NASA Astrophysics Data System (ADS)

    Hildebrandt, L.; Mohr, C.; Lee, B.; Engelhart, G. J.; Decarlo, P. F.; Prevot, A. S.; Baltensperger, U.; Donahue, N. M.; Pandis, S. N.

    2008-12-01

    We present first results on the volatility and chemical composition of aged organic aerosol measured during the Finokalia Aerosol Measurement Experiment - 2008 (FAME-2008). Finokalia is located in the Southeast of Crete, Greece, and this remote site allows for the measurement of aged European aerosol as it is transported from Central to Southeastern Europe. We measured the volatility of the aerosol at Finokalia as a function of its size by combining several instruments. We used an Aerodyne quadrupole aerosol mass spectrometer (Q-AMS) to measure the size-resolved chemical composition of the particles, a scanning mobility particle sizer (SMPS) to measure the volume distribution of particles, and a thermodenuder system to induce changes in size and composition via moderate heating of the particles. The largest fraction of the non-refractory material in the aerosol sampled was ammonium sulfate and ammonium bisulfate, followed by organic material and a small contribution from nitrate. Most of the organic aerosol was highly oxidized, even after only a few days of transport over continental Europe. These highly oxidized organics had lower volatility than fresh primary or secondary aerosol measured in the laboratory. Significant changes in air-parcel trajectories and wind direction led to changes in the chemical composition of the sampled aerosol and corresponding changes of the volatility. These results allow the quantification of the effect of atmospheric processing on organic aerosol volatility and can be used as constraints for atmospheric Chemical Transport Models that predict the aerosol volatility.

  7. Fungal contribution to size-segregated aerosol measured through biomarkers

    NASA Astrophysics Data System (ADS)

    Di Filippo, Patrizia; Pomata, Donatella; Riccardi, Carmela; Buiarelli, Francesca; Perrino, Cinzia

    2013-01-01

    Fungal spores are the dominant biological component of air. Although ubiquitous in outdoor air, they are scarcely measured due to the inadequacy of measurement methods. The use of biomarkers as tools for the determination of fungal contribution to bioaerosol has often been suggested, and ergosterol, arabitol and mannitol have been associated to fungal spores as tracers. In the present paper, the fungal component of aerosol was studied at suburban/rural and at urban sites. Ergosterol, arabitol, and mannitol contents in airborne particulate matter, even at different sizes, were determined. Literature conversion factors and calculated conversion factors correlating ergosterol, arabitol, and mannitol masses to fungi mass were applied and compared to each other. The obtained fungal spore concentrations were different depending on the marker utilized both with the conversion factors found in literature and the calculated ones. Size-segregated marker distribution suggested different sources for the three tracers indicating ergosterol as the only reliable biomarker at our latitudes. The fungal spore concentrations were higher at the suburban/rural location and respectively inversely and directly proportional to temperature and relative humidity.

  8. Fast Airborne Size Distribution Measurements of an Aerosol Processes and Aging

    NASA Astrophysics Data System (ADS)

    Kapustin, V.; Clarke, A. D.; Zhou, J.; Brekhovskikh, V.; McNaughton, C. S.; Howell, S.

    2009-12-01

    During MILAGRO/INTEX experiment the Hawaii Group for Environmental Aerosol Research (HIGEAR) deployed a wide range of aerosol instrumentation aboard NSF C-130 and NASA DC-8. These were designed to provide rapid information on aerosol composition, state of mixing (internal or external), spectral optical properties (scattering and absorption), the humidity dependence of light scattering - f(RH), and the role of condensed species in changing the absorption properties of black carbon (BC) and inferred properties of organic carbon (OC). We also flew the Fast Mobility Particle Spectrometer (FMPS, TSI Inc.) to measure aerosol size distributions in a range 5.6 - 560 nm. For all our flights around Mexico City, an aerosol number concentration usually was well above the nominal FMPS sensitivity (from ~100 particles/cc @ Dp = 5.6 nm to 1 part/cc @ 560nm), providing us with reliable size distributions even at 1 sec resolution. FMPS measurements revealed small scale structure of an aerosol and allowed us to examine size distributions varying over space and time associated with mixing processes previously unresolved. These 1-Hz measurements during aircraft profiles captured variations in size distributions within shallow layers. Other dynamic processes observed included orography induced aerosol layers and evolution of the nanoparticles formed by nucleation. We put FMPS high resolution size distribution data in a context of aerosol evolution and aging, using a range of established (for MIRAGE/INTEX) chemical, aerosol and transport aging parameters.

  9. Aerosol size distribution and radiative forcing response to anthropogenically driven historical changes in biogenic secondary organic aerosol formation

    NASA Astrophysics Data System (ADS)

    D'Andrea, S. D.; Acosta Navarro, J. C.; Farina, S. C.; Scott, C. E.; Rap, A.; Farmer, D. K.; Spracklen, D. V.; Riipinen, I.; Pierce, J. R.

    2015-03-01

    Emissions of biogenic volatile organic compounds (BVOCs) have changed in the past millennium due to changes in land use, temperature, and CO2 concentrations. Recent reconstructions of BVOC emissions have predicted that global isoprene emissions have decreased, while monoterpene and sesquiterpene emissions have increased; however, all three show regional variability due to competition between the various influencing factors. In this work, we use two modeled estimates of BVOC emissions from the years 1000 to 2000 to test the effect of anthropogenic changes to BVOC emissions on secondary organic aerosol (SOA) formation, global aerosol size distributions, and radiative effects using the GEOS-Chem-TOMAS (Goddard Earth Observing System; TwO-Moment Aerosol Sectional) global aerosol microphysics model. With anthropogenic emissions (e.g., SO2, NOx, primary aerosols) turned off and BVOC emissions changed from year 1000 to year 2000 values, decreases in the number concentration of particles of size Dp > 80 nm (N80) of > 25% in year 2000 relative to year 1000 were predicted in regions with extensive land-use changes since year 1000 which led to regional increases in the combined aerosol radiative effect (direct and indirect) of > 0.5 W m-2 in these regions. We test the sensitivity of our results to BVOC emissions inventory, SOA yields, and the presence of anthropogenic emissions; however, the qualitative response of the model to historic BVOC changes remains the same in all cases. Accounting for these uncertainties, we estimate millennial changes in BVOC emissions cause a global mean direct effect of between +0.022 and +0.163 W m-2 and the global mean cloud-albedo aerosol indirect effect of between -0.008 and -0.056 W m-2. This change in aerosols, and the associated radiative forcing, could be a largely overlooked and important anthropogenic aerosol effect on regional climates.

  10. Aerosol-fluorescence spectrum analyzer: real-time measurement of emission spectra of airborne biological particles

    NASA Astrophysics Data System (ADS)

    Hill, Steven C.; Pinnick, Ronald G.; Nachman, Paul; Chen, Gang; Chang, Richard K.; Mayo, Michael W.; Fernandez, Gilbert L.

    1995-10-01

    We have assembled an aerosol-fluorescence spectrum analyzer (AFS), which can measure the fluorescence spectra and elastic scattering of airborne particles as they flow through a laser beam. The aerosols traverse a scattering cell where they are illuminated with intense (50 kW/cm 2) light inside the cavity of an argon-ion laser operating at 488 nm. This AFS can obtain fluorescence spectra of individual dye-doped polystyrene microspheres as small as 0.5 mu m in diameter. The spectra obtained from microspheres doped with pink and green-yellow dyes are clearly different. We have also detected the fluorescence spectra of airborne particles (although not single particles) made from various

  11. Engineering Upgrades to the Radionuclide Aerosol Sampler/Analyzer for the CTBT International Monitoring System

    SciTech Connect

    Forrester, Joel B.; Carty, Fitz; Comes, Laura; Hayes, James C.; Miley, Harry S.; Morris, Scott J.; Ripplinger, Mike D.; Slaugh, Ryan W.; Van Davelaar, Peter

    2013-05-13

    The Radionuclide Aerosol Sampler/Analyzer (RASA) is an automated aerosol collection and analysis system designed by Pacific Northwest National Laboratory in the 1990’s and is deployed in several locations around the world as part of the International Monitoring System (IMS) required under the Comprehensive Nuclear-Test-Ban Treaty (CTBT). The utility of such an automated system is the reduction of human intervention and the production of perfectly uniform results. However, maintainability and down time issues threaten this utility, even for systems with over 90% data availability. Engineering upgrades to the RASA are currently being pursued to address these issues, as well as Fukushima lessons learned. Current work includes a new automation control unit, and other potential improvements such as alternative detector cooling and sampling options are under review. This paper presents the current state of upgrades and improvements under investigation

  12. Effects of aerosol sources and chemical compositions on cloud drop sizes and glaciation temperatures

    NASA Astrophysics Data System (ADS)

    Zipori, Assaf; Rosenfeld, Daniel; Tirosh, Ofir; Teutsch, Nadya; Erel, Yigal

    2015-09-01

    The effect of aerosols on cloud properties, such as its droplet sizes and its glaciation temperatures, depends on their compositions and concentrations. In order to examine these effects, we collected rain samples in northern Israel during five winters (2008-2011 and 2013) and determined their chemical composition, which was later used to identify the aerosols' sources. By combining the chemical data with satellite-retrieved cloud properties, we linked the aerosol types, sources, and concentrations with the cloud glaciation temperatures (Tg). The presence of dust increased Tg from -26°C to -12°C already at relatively low dust concentrations. This result is in agreement with the conventional wisdom that desert dust serves as good ice nuclei (INs). With higher dust concentrations, Tg saturated at -12°C, even though cloud droplet sizes decreased as a result of the cloud condensation nucleating (CCN) activity of the dust. Marine air masses also encouraged freezing, but in this case, freezing was enhanced by the larger cloud droplet sizes in the air masses (caused by low CCN concentrations) and not by IN concentrations or by aerosol type. An increased fraction of anthropogenic aerosols in marine air masses caused a decrease in Tg, indicating that these aerosols served as poor IN. Anthropogenic aerosols reduced cloud droplet sizes, which further decreased Tg. Our results could be useful in climate models for aerosol-cloud interactions, as we investigated the effects of aerosols of different sources on cloud properties. Such parameterization can simplify these models substantially.

  13. Source and composition of size fractionated aerosols collected in the Central Valley

    NASA Astrophysics Data System (ADS)

    Allen, G.; Kelly, P. B.; Buchholz, B. A.; Clifford, A.

    2013-12-01

    The Central Valley in California has historically had high levels of atmospheric particulate matter (PM), resulting in significant adverse health effects. The three sources of atmospheric PM in the Central Valley are vehicle exhaust emissions, agricultural activity and residential wood burning. Ambient PM was collected during the winter of 2011 and 2012 in Davis, CA using a DRUM impact analyzer to determine the contributions of the various sources to the size fractionated aerosols. Laser desorption ionization time-of-flight mass spectrometry (LDI-TOF MS) and radiocarbon accelerator mass spectrometry (AMS) were performed on size fractionated atmospheric PM. The results show that as particle size decreases the amount of organic carbon increases. In the smallest size fraction (0.09 - 1.2 μm) the organic carbon encompasses approximately 70% of the LDI-TOF signal intensity. A comparison of the size fraction PM LDI-TOF spectra showed that there was a significant difference in the chemical composition with particle size. Three distinct chemical composition modes were observed in the LDI-TOF analysis: 0.09 to 0.34 μm, 0.34 to 0.56 μm and >0.56 μm. The particles <0.34 μm were found to be statistically different than those >0.5 μm. The chemical difference in the PM is driven by the large amount of secondary organic aerosol. Dicarboxylic acids, aromatic acids and nitrated aromatics were predominately found in particles <0.34 μm. The effect on human health of these compounds needs to be further explored. The difference in the chemical composition between the respirable and larger PM needs to be considered when associating health effects with PM exposure. The radiocarbon AMS analysis showed that the size fractionated total carbonaceous particulate matter was mainly biogenic in origin, having an average fraction modern (F14C) = 0.753 × 0.006. The F14C from both sample collections were similar and there wasn't a significant change in fraction modern as particle size

  14. Performance comparison of Malvern instruments laser diffraction drop size analyzer

    NASA Technical Reports Server (NTRS)

    Hirleman, E. D.; Dodge, L. G.

    1986-01-01

    The performance of ten laser diffraction particle sizing instruments (Malvern models 2200 and 2600) has been evaluated using a synthetic particle size reference standard in a round-robin test at nine independent laboratories. A calibration reticle consisting of a two-dimensional array of opaque, circular particle images photoetched in chrome thin film deposited on a glass substrate was used as the reference. Mean diameters (e.g., D32) for the reticle measured by the ten unmodified instruments varied by 27 percent. In contrast, data from six instruments with individually calibrated photodetector correction factors demonstrated much better agreement and were within 2.6 percent of the actual reticle properties.

  15. Use of stable carbon and nitrogen isotope ratios in size segregated aerosol particles for the O/I penetration evaluation

    NASA Astrophysics Data System (ADS)

    Garbaras, Andrius; Garbariene, Inga; Masalaite, Agne; Ceburnis, Darius; Krugly, Edvinas; Kvietkus, Kestutis; Remeikis, Vidmantas; Martuzevicius, Dainius

    2015-04-01

    Stable carbon and nitrogen isotope ratio are successfully used in the atmospheric aerosol particle source identification [1, 2], transformation, pollution [3] research. The main purpose of this study was to evaluate the penetration of atmospheric aerosol particles from outdoor to indoor using stable carbon and nitrogen isotope ratios. Six houses in Kaunas (Lithuania) were investigated during February and March 2013. Electrical low pressure impactor was used to measure in real time concentration and size distribution of outdoor aerosol particles. ELPI+ includes 15 channels covering the size range from 0.017 to 10.0 µm. The 25 mm diameter aluminium foils were used to collect aerosol particles. Gravimetric analysis of samples was made using microbalance. In parallel, indoor aerosol samples were collected with a micro-orifice uniform deposition impactor (MOUDI model 110), where the aerosol particles were separated with the nominal D50 cut-off sizes of 0.056, 0.1, 0.18,0.32,0.56, 1.0, 1.8, 3.2, 5.6, 10, 18 μm for impactor stages 1-11, respectively. The impactor was run at a flow rate of 30 L/min. Air quality meters were used to record meteorological conditions (temperature, relative humidity) during the investigated period. All aerosol samples were analyzed for total carbon (TC) and total nitrogen (TN) contents and their isotopic compositions using elemental analyzer (EA) connected to the stable isotope ratio mass spectrometer (IRMS). TC concentration in indoors ranged from 1.5 to 247.5 µg/m3. During the sampling period outdoors TN levels ranged from 0.1 to 10.9 µg/m3. The obtained outdoor δ13C(PM2.5) values varied from -24.21 to -26.3‰, while the δ15N values varied from 2.4 to 11.1 ‰ (average 7.2±2.5 ‰). Indoors carbonaceous aerosol particles were depleted in 13C compared to outdoors in all sampling sites. This depletion in δ13C varied from 0.1 to 3.2 ‰. We think that this depletion occurs due ongoing chemical reactions (oxidation) when aerosol

  16. Size-Time-Composition Resolved Study of Aerosols Across El Paso, Texas in Fall 2008

    NASA Astrophysics Data System (ADS)

    Cahill, T. A.; Gill, T. E.; Pingitore, N. E.; Olvera, H. A.; Clague, J. W.; Barnes, D. E.; Perry, K. D.; Li, W.; Amaya, M. A.

    2009-12-01

    Systematic variations in the absolute amounts, size and composition of airborne particulate matter (PM) across the El Paso, Texas metropolitan area may differentially impact the respiratory status (e.g., asthma) and overall health of the local population. To understand these variations, we collected size-time resolved samples of PM with DRUM samplers during a one-month period in late autumn 2008 at three sites along a NW-SE (roughly upwind-downwind) transect across El Paso’s airshed. The DRUM sampler is a rotating-drum impactor separating and collecting aerosols on Mylar strips mounted on the drums, in 8 size stages from 10 μm to <0.1 μm. DRUM strips are analyzed with 3-hr time resolution by β-gauge for mass and by synchrotron X-ray fluorescence for elemental composition. We collected samples at Santa Teresa, New Mexico (a minimally developed area NW of El Paso, at the edge of a sparsely-inhabited expanse of the Chihuahuan Desert), at the edge of the University of Texas- El Paso (UTEP) campus (in the urban core of El Paso), and at Socorro, Texas (a suburban area in the valley of the Rio Grande, SE of the urban core). Results illustrate sharp excursions in mass and element concentrations in aerosol-laden periods lasting from several hours to several days, associated with stagnant air, inversions, smoke events, dust/high wind/frontal passage, and/or daily traffic patterns, punctuated by several periods of reduced aerosol levels after Pacific frontal passages. Mass and absorption data show an increasing influence of carbonaceous (absorbing) aerosols with decreasing particle size <~1 μm, and increasing influence of mineral (scattering) aerosols with increasing particle size >~1 μm. Calcium/silicon ratios were high (>1), especially in coarser stages and during high wind events, reflecting wind erosion of the Chihuahuan Desert’s calcareous soils. Concentrations of chlorine, silicon, calcium, coarse potassium, and lead increased during high wind events, while

  17. Chemical and statistical interpretation of sized aerosol particles collected at an urban site in Thessaloniki, Greece.

    PubMed

    Tsitouridou, Roxani; Papazova, Petia; Simeonova, Pavlina; Simeonov, Vasil

    2013-01-01

    The size distribution of aerosol particles (PM0.015-PM18) in relation to their soluble inorganic species and total water soluble organic compounds (WSOC) was investigated at an urban site of Thessaloniki, Northern Greece. The sampling period was from February to July 2007. The determined compounds were compared with mass concentrations of the PM fractions for nano (N: 0.015 < Dp < 0.06), ultrafine (UFP: 0.015 < Dp < 0.125), fine (FP: 0.015 < Dp < 2.0) and coarse particles (CP: 2.0 < Dp < 8.0) in order to perform mass closure of the water soluble content for the respective fractions. Electrolytes were the dominant species in all fractions (24-27%), followed by WSOC (16-23%). The water soluble inorganic and organic content was found to account for 53% of the nanoparticle, 48% of the ultrafine particle, 45% of the fine particle and 44% of the coarse particle mass. Correlations between the analyzed species were performed and the effect of local and long-range transported emissions was examined by wind direction and backward air mass trajectories. Multivariate statistical analysis (cluster analysis and principal components analysis) of the collected data was performed in order to reveal the specific data structure. Possible sources of air pollution were identified and an attempt is made to find patterns of similarity between the different sized aerosols and the seasons of monitoring. It was proven that several major latent factors are responsible for the data structure despite the size of the aerosols - mineral (soil) dust, sea sprays, secondary emissions, combustion sources and industrial impact. The seasonal separation proved to be not very specific. PMID:24007436

  18. AnalySize: New software for analyzing and unmixing sediment grain size distribution spectra

    NASA Astrophysics Data System (ADS)

    Paterson, G. A.; Heslop, D.

    2015-12-01

    Grain size distribution (GSD) data are a widely used tool in Earth sciences, particularly in understanding sediment transportation and sourcing. Although large data sets are regularly generated, detailed numerical analyses, such as grain size unmixing, are not routinely performed. Unmixing of GSD data involves approximating a given data set by a small number of GSDs, known as end members. These end members, along with their relative abundances, can be used to fully characterize the variability of the data. End member analysis (EMA), which fits one set of end members to a single data set, is one the most robust ways to do this. This approach estimates the form of the end members from the data set itself; hence it is a non-parametric approach. Available algorithms, however, either produce sub-optimal solutions, or are time consuming. To aid investigators in exploring the full potential of their data, we introduce AnalySize, which is a GUI based tool that allows for comprehensive processing and unmixing of grain size data obtained from laser diffraction particle grain size analyzers. AnalySize brings together methods from other disciplines in Earth sciences as well as introducing new techniques and improvements to provide a complete software package for unmixing GSD data. The software utilizes the rapid HALS-NMF algorithm from hyperspectral image analysis to perform non-parametric EMA, which is demonstrated to yield results that are an improvement over algorithms currently used in GSD analysis. Non-parametric EMA, however, is often unable to clearly identify discrete unimodal grain size sub-populations, which can more detailed information about sediment sources. To alleviate this, we introduce a new algorithm to perform parametric EMA, whereby an entire GSD data set can be unmixed into unimodal parametric end members (e.g., lognormal or Weibull end members). This allows individual grain size sub-populations to be more readily identifiable in highly mixed data set

  19. IS THE SIZE DISTRIBUTION OF URBAN AEROSOLS DETERMINED BY THERMODYNAMIC EQUILIBRIUM? (R826371C005)

    EPA Science Inventory

    A size-resolved equilibrium model, SELIQUID, is presented and used to simulate the size–composition distribution of semi-volatile inorganic aerosol in an urban environment. The model uses the efflorescence branch of aerosol behavior to predict the equilibrium partitioni...

  20. TIME-OF-FLIGHT AEROSOL BEAM SPECTROMETER FOR PARTICLE SIZE MEASUREMENTS

    EPA Science Inventory

    A time-of-flight aerosol beam spectrometer (TOFABS) is described. The instrument has been designed and constructed to perform in situ real time measurements of the aerodynamic size of individual aerosol particles in the range 0.3 to 10 micrometers diameter. The measurement method...

  1. Online Aerosol Mass Spectrometry of Single Micrometer-Sized Particles Containing Poly(ethylene glycol)

    SciTech Connect

    Bogan, M J; Patton, E; Srivastava, A; Martin, S; Fergenson, D; Steele, P; Tobias, H; Gard, E; Frank, M

    2006-10-25

    Analysis of poly(ethylene glycol)(PEG)-containing particles by online single particle aerosol mass spectrometers equipped with laser desorption ionization (LDI) is reported. We demonstrate that PEG-containing particles are useful in the development of aerosol mass spectrometers because of their ease of preparation, low cost, and inherently recognizable mass spectra. Solutions containing millimolar quantities of PEGs were nebulized and, after drying, the resultant micrometer-sized PEG containing particles were sampled. LDI (266 nm) of particles containing NaCl and PEG molecules of average molecular weight <500 generated mass spectra reminiscent of mass spectra of PEG collected by other MS schemes including the characteristic distribution of positive ions (Na{sup +} adducts) separated by the 44 Da of the ethylene oxide units separating each degree of polymerization. PEGs of average molecular weight >500 were detected from particles that also contained t the tripeptide tyrosine-tyrosine-tyrosine or 2,5-dihydroxybenzoic acid, which were added to nebulized solutions to act as matrices to assist LDI using pulsed 266 nm and 355 nm lasers, respectively. Experiments were performed on two aerosol mass spectrometers, one reflectron and one linear, that each utilize two time-of-flight mass analyzers to detect positive and negative ions created from a single particle. PEG-containing particles are currently being employed in the optimization of our bioaerosol mass spectrometers for the application of measurements of complex biological samples, including human effluents, and we recommend that the same strategies will be of great utility to the development of any online aerosol LDI mass spectrometer platform.

  2. Cloud Nucleating Properties of Aerosols During TexAQS - GoMACCS 2006: Influence of Aerosol Sources, Composition, and Size

    NASA Astrophysics Data System (ADS)

    Quinn, P. K.; Bates, T. S.; Coffman, D. J.; Covert, D. S.; Onasch, T. B.; Alllan, J. D.; Worsnop, D.

    2006-12-01

    TexAQS - GoMACCS 2006 was conducted from July to September 2006 in the Gulf of Mexico and Houston Ship Channel to investigate sources and processing of gas and particulate phase species and to determine their impact on regional air quality and climate. As part of the experiment, the NOAA R.V. Ronald H. Brown transited from Charleston, S.C. to the study region. The ship was equipped with a full compliment of gas and aerosol instruments. To determine the cloud nucleating properties of aerosols, measurements were made of the aerosol number size distribution, aerosol chemical composition, and cloud condensation nuclei (CCN) concentration at five supersaturations. During the transit and over the course of the experiment, a wide range of aerosol sources and types was encountered. These included urban and industrial emissions from the S.E. U.S. as the ship left Charleston, a mixture of Saharan dust and marine aerosol during the transit around Florida and across the Gulf of Mexico, urban emissions from Houston, and emissions from the petrochemical industries, oil platforms, and marine vessels in the Gulf coast region. Highest activation ratios (ratio of CCN to total particle number concentration at 0.4 percent supersaturation) were measured in anthropogenic air masses when the aerosol was composed primarily of ammonium sulfate salts and in marine air masses with an aerosol composed of sulfate and sea salt. A strong gradient in activation ratio was measured as the ship moved from the Gulf of Mexico to the end of the Houston Ship Channel (values decreasing from about 0.8 to less than 0.1) and the aerosol changed from marine to industrial. The activation ratio under these different regimes in addition to downwind of marine vessels and oil platforms will be discussed in the context of the aerosol size distribution and chemical composition. The discussion of composition will include the organic mass fraction of the aerosol, the degree of oxidation of the organics, and the water

  3. Development and application of an aerosol screening model for size-resolved urban aerosols.

    PubMed

    Stanier, Charles O; Lee, Sang-Rin

    2014-06-01

    Predictive models of vehicular ultrafine particles less than 0.1 microm in diameter (UFPs*) and other urban pollutants with high spatial and temporal variation are useful and important in applications such as (1) decision support for infrastructure projects, emissions controls, and transportation-mode shifts; (2) the interpretation and enhancement of observations (e.g., source apportionment, extrapolation, interpolation, and gap-filling in space and time); and (3) the generation of spatially and temporally resolved exposure estimates where monitoring is unfeasible. The objective of the current study was to develop, test, and apply the Aerosol Screening Model (ASM), a new physically based vehicular UFP model for use in near-road environments. The ASM simulates hourly average outdoor concentrations of roadway-derived aerosols and gases. Its distinguishing features include user-specified spatial resolution; use of the Weather Research and Forecasting (WRF) meteorologic model for winds estimates; use of a database of more than 100,000 road segments in the Los Angeles, California, region, including freeway ramps and local streets; and extensive testing against more than 9000 hours of observed particle concentrations at 11 sites. After initialization of air parcels at an upwind boundary, the model solves for vehicle emissions, dispersion, coagulation, and deposition using a Lagrangian modeling framework. The Lagrangian parcel of air is subdivided vertically (into 11 levels) and in the crosswind direction (into 3 parcels). It has overall dimensions of 10 m (downwind), 300 m (vertically), and 2.1 km (crosswind). The simulation is typically started 4 km upwind from the receptor, that is, the location at which the exposure is to be estimated. As parcels approach the receptor, depending on the user-specified resolution, step size is decreased, and crosswind resolution is enhanced through subdivision of parcels in the crosswind direction. Hourly concentrations and size

  4. Identification of key aerosol populations through their size and composition resolved spectral scattering and absorption

    NASA Astrophysics Data System (ADS)

    Costabile, F.; Barnaba, F.; Angelini, F.; Gobbi, G. P.

    2013-03-01

    Characterizing chemical and physical aerosol properties is important to understand their sources, effects, and feedback mechanisms in the atmosphere. This study proposes a scheme to classify aerosol populations based on their spectral optical properties (absorption and scattering). The scheme is obtained thanks to the outstanding set of information on particle size and composition these properties contain. The spectral variability of the aerosol single scattering albedo (dSSA), and the extinction, scattering and absorption Angstrom exponents (EAE, SAE and AAE, respectively) were observed on the basis of two-year measurements of aerosol optical properties (scattering and absorption coefficients at blue, green and red wavelengths) performed in the suburbs of Rome (Italy). Optical measurements of various aerosol types were coupled to measurements of particle number size distributions and relevant optical properties simulations (Mie theory). These latter allowed the investigation of the role of the particle size and composition in the bulk aerosol properties observed. The combination of simulations and measurements suggested a general "paradigm" built on dSSA, SAE and AAE to optically classify aerosols. The paradigm proved suitable to identify the presence of key aerosol populations, including soot, biomass burning, organics, dust and marine particles. The work highlights that (i) aerosol populations show distinctive combinations of SAE and dSSA times AAE, these variables being linked by a linear inverse relation varying with varying SSA; (ii) fine particles show EAE > 1.5, whilst EAE < 2 is found for both coarse particles and ultrafine soot-rich aerosols; (iii) fine and coarse particles both show SSA > 0.8, whilst ultrafine urban Aitken mode and soot particles show SSA < 0.8. The proposed paradigm agrees with aerosol observations performed during past major field campaigns, this indicating that relations concerning the paradigm have a general validity.

  5. Chemical and size effects of hygroscopic aerosols on light scattering coefficients

    NASA Astrophysics Data System (ADS)

    Tang, Ignatius N.

    1996-08-01

    The extensive thermodynamic and optical properties recently reported [Tang and Munkelwitz, 1994a] for sulfate and nitrate solution droplets are incorporated into a visibility model for computing light scattering by hygroscopic aerosols. The following aerosol systems are considered: NH4HSO4, (NH4)2SO4, (NH4)3H(SO4), NaHSO4, Na2SO4, NH4NO3, and NaNO3. In addition, H2SO4 and NaCl are included to represent freshly formed sulfate and background sea-salt aerosols, respectively. Scattering coefficients, based on 1 μg dry salt per cubic meter of air, are calculated as a function of relative humidity for aerosols of various chemical compositions and lognormal size distributions. For a given size distribution the light scattered by aerosol particles per unit dry-salt mass concentration is only weakly dependent on chemical constituents of the hygroscopic sulfate and nitrate aerosols. Sulfuric acid and sodium chloride aerosols, however, are exceptions and scatter light more efficiently than all other inorganic salt aerosols considered in this study. Both internal and external mixtures exhibit similar light-scattering properties. Thus for common sulfate and nitrate aerosols, since the chemical effect is outweighed by the size effect, it follows that observed light scattering by the ambient aerosol can be approximated, within practical measurement uncertainties, by assuming the aerosol being an external mixture. This has a definite advantage for either visibility degradation or climatic impact modeling calculations, because relevant data are now available for external mixtures but only very scarce for internal mixtures.

  6. ANALYSIS OF RESPIRATORY DESPOSITION DOSE OF INHALED AMBIENT AEROSOLS FOR DIFFERENT SIZE FRACTIONS

    EPA Science Inventory

    ANALYSIS OF RESPIRATORY DEPOSITION DOSE OF INHALED AMBIENT AEROSOLS FOR DIFFERENT SIZE FRACTIONS. Chong S. Kim, SC. Hu**, PA Jaques*, US EPA, National Health and Environmental Effects Research Laboratory, Research Triangle Park, NC 27711; **IIT Research Institute, Chicago, IL; *S...

  7. Multi-modal analysis of aerosol robotic network size distributions for remote sensing applications: dominant aerosol type cases

    NASA Astrophysics Data System (ADS)

    Taylor, M.; Kazadzis, S.; Gerasopoulos, E.

    2014-03-01

    To date, size distributions obtained from the aerosol robotic network (AERONET) have been fit with bi-lognormals defined by six secondary microphysical parameters: the volume concentration, effective radius, and the variance of fine and coarse particle modes. However, since the total integrated volume concentration is easily calculated and can be used as an accurate constraint, the problem of fitting the size distribution can be reduced to that of deducing a single free parameter - the mode separation point. We present a method for determining the mode separation point for equivalent-volume bi-lognormal distributions based on optimization of the root mean squared error and the coefficient of determination. The extracted secondary parameters are compared with those provided by AERONET's Level 2.0 Version 2 inversion algorithm for a set of benchmark dominant aerosol types, including desert dust, biomass burning aerosol, urban sulphate and sea salt. The total volume concentration constraint is then also lifted by performing multi-modal fits to the size distribution using nested Gaussian mixture models, and a method is presented for automating the selection of the optimal number of modes using a stopping condition based on Fisher statistics and via the application of statistical hypothesis testing. It is found that the method for optimizing the location of the mode separation point is independent of the shape of the aerosol volume size distribution (AVSD), does not require the existence of a local minimum in the size interval 0.439 μm ≤ r ≤ 0.992 μm, and shows some potential for optimizing the bi-lognormal fitting procedure used by AERONET particularly in the case of desert dust aerosol. The AVSD of impure marine aerosol is found to require three modes. In this particular case, bi-lognormals fail to recover key features of the AVSD. Fitting the AVSD more generally with multi-modal models allows automatic detection of a statistically significant number of aerosol

  8. Evaluation of a size-resolved aerosol model based on satellite and ground observations and its implication on aerosol forcing

    NASA Astrophysics Data System (ADS)

    Ma, Xiaoyan; Yu, Fangqun

    2016-04-01

    The latest AeroCom phase II experiments have showed a large diversity in the simulations of aerosol concentrations, size distribution, vertical profile, and optical properties among 16 detailed global aerosol microphysics models, which contribute to the large uncertainty in the predicted aerosol radiative forcing and possibly induce the distinct climate change in the future. In the last few years, we have developed and improved a global size-resolved aerosol model (Yu and Luo, 2009; Ma et al., 2012; Yu et al., 2012), GEOS-Chem-APM, which is a prognostic multi-type, multi-component, size-resolved aerosol microphysics model, including state-of-the-art nucleation schemes and condensation of low volatile secondary organic compounds from successive oxidation aging. The model is one of 16 global models for AeroCom phase II and participated in a couple of model inter-comparison experiments. In this study, we employed multi-year aerosol optical depth (AOD) data from 2004 to 2012 taken from ground-based Aerosol Robotic Network (AERONET) measurements and Moderate Resolution Imaging Spectroradiometer (MODIS), Multiangle Imaging SpectroRadiometer (MISR) and Sea-viewing Wide Field-of-view Sensor (SeaWiFS) satellite retrievals to evaluate the performance of the GEOS-Chem-APM in predicting aerosol optical depth, including spatial distribution, reginal variation and seasonal variabilities. Compared to the observations, the modelled AOD is overall good over land, but quite low over ocean possibly due to low sea salt emission in the model and/or higher AOD in satellite retrievals, specifically MODIS and MISR. We chose 72 AERONET sites having at least 36 months data available and representative of high spatial domain to compare with the model and satellite data. Comparisons in various representative regions show that the model overall agrees well in the major anthropogenic emission regions, such as Europe, East Asia and North America. Relative to the observations, the modelled AOD is

  9. Ozone and aerosol tropospheric concentrations variability analyzed using the ADRIMED measurements and the WRF and CHIMERE models

    NASA Astrophysics Data System (ADS)

    Menut, L.; Mailler, S.; Siour, G.; Bessagnet, B.; Turquety, S.; Rea, G.; Briant, R.; Mallet, M.; Sciare, J.; Formenti, P.; Meleux, F.

    2015-06-01

    During the months of June and July 2013, over the Euro-Mediterranean area, the ADRIMED (Aerosol Direct Radiative Impact on the regional climate in the MEDiterranean region) project was dedicated to characterize the ozone and aerosol concentrations in the troposphere. It is first shown that this period was not highly polluted compared to previous summers in this region, with a moderate ozone production, no significant vegetation fire events and several precipitation periods scavenging the aerosol. The period is modeled with the WRF (Weather Research and Forecasting) and CHIMERE models, and their ability to quantify the observed pollution transport events is presented. The CHIMERE model simulating all kinds of sources (anthropogenic, biogenic, mineral dust, vegetation fires); the aerosol speciation, not available with the measurements, is presented: during the whole period, the aerosol was mainly constituted by mineral dust, sea salt and sulfates close to the surface and mainly by mineral dust in the troposphere. Compared to the AERONET (Aerosol Robotic Network) size distribution, it is shown that the model underestimates the coarse mode near mineral dust sources and overestimates the fine mode in the Mediterranean area, highlighting the need to improve the model representation of the aerosol size distribution both during emissions, long-range transport and deposition.

  10. Aerosol optical properties at a coastal site in Hong Kong, South China: temporal features, size dependencies and source analysis

    NASA Astrophysics Data System (ADS)

    Wang, Jiaping; Ding, Aijun; Virkkula, Aki; Lee, Shuncheng; Shen, Yicheng; Chi, Xuguang; Xu, Zheng

    2016-04-01

    Hong Kong is a typical coastal city adjacent to the Pearl River Delta (PRD) region in southern China, which is one of the regions suffering from severe air pollution. Atmospheric aerosols can affect the earth's radiative balance by scattering and absorbing incoming solar radiation. Black Carbon (BC) aerosol is a particularly emphasized component due to its strong light absorption. Aerosol transported from different source areas consists of distinct size distributions, leading to different optical properties. As the byproducts of the incomplete oxidation, BC and CO both have relatively long life time, their relationship is a good indicator for distinguishing different pollutant sources. In this study, temporal variations of aerosol optical properties and concentrations of BC and CO at a coastal background station in Hong Kong were investigated. Transport characteristics and origins of aerosol were elucidated by analyzing backward Lagrangian particle dispersion modeling (LPDM) results, together with related parameters including the relationships between optical properties and particle size, BC-CO correlations, ship location data and meteorological variables. From February 2012 to September 2013 and March 2014 to February 2015, continuous in-situ measurements of light scattering and absorption coefficients, particle size distribution and concentrations of BC and CO were conducted at Hok Tsui (HT), a coastal background station on the southeast tip of Hong Kong Island (22.22°N, 114.25°E, 60 m above the sea level) with few local anthropogenic activities. Affected by the Asian monsoon, this region is dominated by continental outflow in winter and by marine inflow from the South China Sea in summer, which is an ideal station for identifying the transport characteristics of aerosol and their effects on optical properties from different anthropogenic emission sources. 7-day backward Lagrangian particle dispersion modeling was performed for source identification. Three

  11. Size matters in the water uptake and hygroscopic growth of atmospherically relevant multicomponent aerosol particles.

    PubMed

    Laskina, Olga; Morris, Holly S; Grandquist, Joshua R; Qin, Zhen; Stone, Elizabeth A; Tivanski, Alexei V; Grassian, Vicki H

    2015-05-14

    Understanding the interactions of water with atmospheric aerosols is crucial for determining the size, physical state, reactivity, and climate impacts of this important component of the Earth's atmosphere. Here we show that water uptake and hygroscopic growth of multicomponent, atmospherically relevant particles can be size dependent when comparing 100 nm versus ca. 6 μm sized particles. It was determined that particles composed of ammonium sulfate with succinic acid and of a mixture of chlorides typical of the marine environment show size-dependent hygroscopic behavior. Microscopic analysis of the distribution of components within the aerosol particles show that the size dependence is due to differences in the mixing state, that is, whether particles are homogeneously mixed or phase separated, for different sized particles. This morphology-dependent hygroscopicity has consequences for heterogeneous atmospheric chemistry as well as aerosol interactions with electromagnetic radiation and clouds. PMID:25521409

  12. Role of nucleation mechanism on the size dependent morphology of organic aerosol.

    PubMed

    Altaf, Muhammad Bilal; Zuend, Andreas; Freedman, Miriam Arak

    2016-07-28

    The origins of the size dependent morphology of organic aerosol are explored by probing the morphology of poly(ethylene glycol)-400/ammonium sulfate mixtures using cryogenic-transmission electron microscopy. Surprisingly, we observe a size dependence at some compositions, but not at others. Our results suggest that size dependence occurs due to an activated process. PMID:27356885

  13. Massive-scale aircraft observations of giant sea-salt aerosol particle size distributions in atmospheric marine boundary layers

    NASA Astrophysics Data System (ADS)

    Jensen, J. B.

    2015-12-01

    iant sea-salt aerosol particles (dry radius, rd > 0.5 μm) occur nearly everywhere in the marine boundary layer and frequently above. This study presents observations of atmospheric sea-salt size distributions in the range 0.7 < rd < 14 μm based on external impaction of sea-spray aerosol particles onto microscope polycarbonate microscope slides. The slides have very large sample volumes, typically about 250 L over a 10-second sampling period. This provides unprecedented sampling of giant sea-salt particles for flights in marine boundary layer air. The slides were subsequently analyzed in a humidified chamber using dual optical digital microscopy. At a relative humidity of 90% the sea-salt aerosol particles form spherical cap drops. Based on measurement the volume of the spherical cap drop and assuming NaCl composition, the Kohler equation is used to derive the dry salt mass of tens of thousands of individual aerosol particles on each slide. Size distributions are given with a 0.2 μm resolution. The slides were exposed from the NSF/NCAR C-130 research aircraft during the 2008 VOCALS project off the coast of northern Chile and the 2011 ICE-T in the Caribbean. In each deployment, size distributions using hundreds of slides are used to relate fitted log-normal size distributions parameters to wind speed, altitude and other atmospheric conditions. The size distributions provide a unique observational set for initializing cloud models with coarse-mode aerosol particle observations for marine atmospheres.

  14. SIZE DISTRIBUTIONS OF ELEMENTAL CARBON IN ATMOSPHERIC AEROSOLS

    EPA Science Inventory

    Environmental problems caused by atmospheric aerosols are well documented in the specialized literature. Studies reporting on the role of dense clouds of soil particles in past mass extinctions of life on Earth and, more recently (Turco et al., 1983), on calculations of potential...

  15. Change Volumetric Distribution Spectrum of Atmospheric Aerosol Size Before Strong Earthquakes Turkey

    NASA Astrophysics Data System (ADS)

    Kolomin, Maxim

    A comparison of generalized portraits volumetric distribution of atmospheric aerosol size over seismic regions (Turkey) is carried out. The data from the World Observation Network «AERONET» - the results of remote radiometric observations of solar radiation and aerosol content in the atmosphere were used for analysis. Portraits for 30 daily time intervals with crustal earthquakes with magnitude greater than 5 and hypocenter not deeper than 30 kilometers, and for the background variations when the earthquake didn’t occur, were calculated. Abnormality of number effects in the morphology of the spectrum volumetric distribution of atmospheric aerosol size before strong crustal earthquakes was estimated, statistical analysis of identified forerunner effects was held. Possible reasons for changes in spectrum size of aerosols were discussed.

  16. Tropospheric aerosol size distributions simulated by three online global aerosol models using the M7 microphysics module

    SciTech Connect

    Zhang, Kai; Wan, Hui; Wang, Bin; Zhang, Meigen; Feichter, J.; Liu, Xiaohong

    2010-07-14

    Tropospheric aerosol size distributions are simulated by three online global models that employ exactly the same modal approach but differ in many aspects such as model meteorology, natural aerosol emissions, sulfur chemistry, and the parameterization of deposition processes. The main purpose of this study is to identify where the largest inter-model discrepancies occur and what the main reasons are. The number concentrations of different aerosol size ranges are compared among the three models and against observations. Overall all the three models can capture the basic features of the observed aerosol number spatial distributions. The magnitude of the number concentration of each mode is consistent among the three models. Quantitative differences are also clearly detectable. For the soluble and insoluble coarse mode and accumulation mode, inter-model discrepancies mainly result from differences in the sea salt and dust emissions, as well as the different strengths of the convective transport in the meteorological models. For the nucleation mode and the soluble Aitken mode, the spread of the model results is largest in the tropics and in the middle and upper troposphere. Diagnostics and sensitivity experiments suggest that this large spread is closely related to the sulfur cycle in the models, which is strongly affected by the choice of sulfur chemistry scheme, its coupling with the convective transport and wet deposition calculation, and the related meteorological fields such as cloud cover, cloud water content, and precipitation. The aerosol size distributions simulated by the three models are compared to observations in the boundary layer. The characteristic shape and magnitude of the distribution functions are reasonably reproduced in typical conditions (i.e., clean, polluted and transition areas). Biases in the mode parameters over the remote oceans and the China adjacent seas are probably caused by the fixed mode variance in the mathematical formulations used

  17. Tropospheric aerosol size distributions simulated by three online global aerosol models using the M7 microphysics module

    NASA Astrophysics Data System (ADS)

    Zhang, K.; Wan, H.; Wang, B.; Zhang, M.; Feichter, J.; Liu, X.

    2010-03-01

    Tropospheric aerosol size distributions are simulated by three online global models that employ exactly the same modal approach but differ in many aspects such as model meteorology, natural aerosol emissions, sulfur chemistry, and the parameterization of deposition processes. The main purpose of this study is to identify where the largest inter-model discrepancies occur and what the main reasons are. The number concentrations of different aerosol size ranges are compared among the three models and against observations. Overall all the three models can capture the basic features of the observed aerosol number spatial distributions. The magnitude of the number concentration of each mode is consistent among the three models. Quantitative differences are also clearly detectable. For the soluble and insoluble coarse mode and accumulation mode, inter-model discrepancies mainly result from differences in the sea salt and dust emissions, as well as the different strengths of the convective transport in the meteorological models. For the nucleation mode and the soluble Aitken mode, the spread of the model results is largest in the tropics and in the middle and upper troposphere. Diagnostics and sensitivity experiments suggest that this large spread is closely related to the sulfur cycle in the models, which is strongly affected by the choice of sulfur chemistry scheme, its coupling with the convective transport and wet deposition calculation, and the related meteorological fields such as cloud cover, cloud water content, and precipitation. The aerosol size distributions simulated by the three models are compared to observations in the boundary layer. The characteristic shape and magnitude of the distribution functions are reasonably reproduced in typical conditions (i.e., clean, polluted and transition areas). Biases in the mode parameters over the remote oceans and the China adjacent seas are probably caused by the fixed mode variance in the mathematical formulations used

  18. A new stochastic algorithm for inversion of dust aerosol size distribution

    NASA Astrophysics Data System (ADS)

    Wang, Li; Li, Feng; Yang, Ma-ying

    2015-08-01

    Dust aerosol size distribution is an important source of information about atmospheric aerosols, and it can be determined from multiwavelength extinction measurements. This paper describes a stochastic inverse technique based on artificial bee colony (ABC) algorithm to invert the dust aerosol size distribution by light extinction method. The direct problems for the size distribution of water drop and dust particle, which are the main elements of atmospheric aerosols, are solved by the Mie theory and the Lambert-Beer Law in multispectral region. And then, the parameters of three widely used functions, i.e. the log normal distribution (L-N), the Junge distribution (J-J), and the normal distribution (N-N), which can provide the most useful representation of aerosol size distributions, are inversed by the ABC algorithm in the dependent model. Numerical results show that the ABC algorithm can be successfully applied to recover the aerosol size distribution with high feasibility and reliability even in the presence of random noise.

  19. Size-resolved parameterization of primary organic carbon in fresh marine aerosols

    SciTech Connect

    Long, Michael S; Keene, William C; Erickson III, David J

    2009-12-01

    Marine aerosols produced by the bursting of artificially generated bubbles in natural seawater are highly enriched (2 to 3 orders of magnitude based on bulk composition) in marine-derived organic carbon (OC). Production of size-resolved particulate OC was parameterized based on a Langmuir kinetics-type association of OC to bubble plumes in seawater and resulting aerosol as constrained by measurements of aerosol produced from highly productive and oligotrophic seawater. This novel approach is the first to account for the influence of adsorption on the size-resolved association between marine aerosols and OC. Production fluxes were simulated globally with an eight aerosol-size-bin version of the NCAR Community Atmosphere Model (CAM v3.5.07). Simulated number and inorganic sea-salt mass production fell within the range of published estimates based on observationally constrained parameterizations. Because the parameterization does not consider contributions from spume drops, the simulated global mass flux (1.5 x 10{sup 3} Tg y{sup -1}) is near the lower limit of published estimates. The simulated production of aerosol number (2.1 x 10{sup 6} cm{sup -2} s{sup -1}) and OC (49 Tg C y{sup -1}) fall near the upper limits of published estimates and suggest that primary marine aerosols may have greater influences on the physiochemical evolution of the troposphere, radiative transfer and climate, and associated feedbacks on the surface ocean than suggested by previous model studies.

  20. Aerosol measurements at a high-elevation site: composition, size, and cloud condensation nuclei activity

    SciTech Connect

    Friedman, Beth; Zelenyuk, Alla; Beranek, Josef; Kulkarni, Gourihar R.; Pekour, Mikhail S.; Hallar, Anna G.; McCubbin, Ian; Thornton, Joel A.; Cziczo, D. J.

    2013-12-09

    We present measurements of CCN concentrations and associated aerosol composition and size properties at a high-elevation research site in March 2011. CCN closure and aerosol hygroscopicity were assessed using simplified assumptions of bulk aerosol properties as well as a new method utilizing single particle composition and size to assess the importance of particle mixing state in CCN activation. Free troposphere analysis found no significant difference between the CCN activity of free tropospheric aerosol and boundary layer aerosol at this location. Closure results indicate that using only size and number information leads to adequate prediction, in the majority of cases within 50%, of CCN concentrations, while incorporating the hygroscopicity parameters of the individual aerosol components measured by single particle mass spectrometry adds to the agreement, in most cases within 20%, between predicted and measured CCN concentrations. For high-elevation continental sites, with largely aged aerosol and low amounts of local area emissions, a lack of chemical knowledge and hygroscopicity may not hinder models in predicting CCN concentrations. At sites influenced by fresh emissions or more heterogeneous particle types, single particle composition information may be more useful in predicting CCN concentrations and understanding the importance of particle mixing state on CCN activation.

  1. Sizing of individual aerosol particles using TAOS (Two-dimensional Angular Optical Scattering) pattern total intensity

    NASA Astrophysics Data System (ADS)

    Zallie, J. T.; Aptowicz, K. B.; Martin, S.; Pan, Y.

    2015-12-01

    The morphology of single aerosol particles has been explored previously using the TAOS (Two-dimensional Angular Optical Scattering) technique, which captures angularly resolved scattering patterns. Particle size is known to strongly influence the light scattering properties of aerosols and therefore is a critical parameter to discern from the TAOS patterns. In this work, T-matrix simulation of light scattering from spherical and spheroidal particles is used to explore the possibility of sizing particles from the total light scattering signal detected using the TAOS technique. Scattering patterns were calculated for particles that span various particle sizes, spheroidal shapes, complex refractive indices and particles orientations representative of atmospheric aerosol distributions. A power law relationship between particle size and total scattering intensity was found that could crudely size particles but with significant error.

  2. GNI - A System for the Impaction and Automated Optical Sizing of Giant Aerosol Particles with Emphasis on Sea Salt

    NASA Astrophysics Data System (ADS)

    Jensen, Jorgen

    2013-04-01

    Size distributions of giant aerosol particles (e.g. sea-salt particles, dry radius larger than 0.5 μm) are not well characterized in the atmosphere, yet they contribute greatly to both direct and indirect aerosol effects. Measurements are problematic for these particles because they (i) occur in low concentrations, (ii) have difficulty in passing through air inlets, (iii) there are problems in discriminating between dry and deliquesced particles, (iv) and impaction sampling requires labor intensive methods. In this study, a simple, high-volume impaction system called the Giant Nuclei Impactor (GNI), based on free-stream exposure of polycarbonate slides from aircraft is described, along with an automated optical microscope-based system for analysis of the impacted particles. The impaction slides are analyzed in a humidity-controlled box (typically 90% relative humidity) that allows for deliquescence of sea salt particles. A computer controlled optical microscope with two digital cameras is used to acquire and analyze images of the aerosol particles. Salt particles will form near-spherical cap solution drops at high relative humidity. The salt mass in each giant aerosol particle is then calculated using simple geometry and K ̈ohler theory by assuming a NaCl composition. The system has a sample volume of about 10 L/s at aircraft speeds of 105 m/s. For salt particles, the measurement range is from about 0.7 μm dry radius to tens of micrometers, with a size-bin resolution of 0.2 μm dry radius. The sizing accuracy was tested using glass beads of known size. Characterizing the uncertainties of observational data is critical for applications to atmospheric science studies. A comprehensive uncertainty analysis is performed for the airborne GNI manual impaction and automatic optical microscope system for sizing giant aerosol particles, with particular emphasis on sea-salt particles. The factors included are (i) sizing accuracy, (ii) concentration accuracy, (iii

  3. Particle size distribution of the stratospheric aerosol from SCIAMACHY limb measurements

    NASA Astrophysics Data System (ADS)

    Rozanov, Alexei; Malinina, Elizaveta; Rozanov, Vladimir; Hommel, Rene; Burrows, John

    2016-04-01

    Stratospheric aerosols are of a great scientific interest because of their crucial role in the Earth's radiative budget as well as their contribution to chemical processes resulting in ozone depletion. While the permanent aerosol background in the stratosphere is determined by the tropical injection of SO2, COS and sulphate particles from the troposphere, major perturbations of the stratospheric aerosol layer result form an uplift of SO2 after strong volcanic eruptions. Satellite measurements in the visible spectral range represent one of the most important sources of information about the vertical distribution of the stratospheric aerosol on the global scale. This study employs measurements of the scattered solar light performed in the limb viewing geometry from the space borne spectrometer SCIAMACHY, which operated onboard the ENVISAT satellite, from August 2002 to April 2012. A retrieval approach to obtain parameters of the stratospheric aerosol particle size distribution will be reported along with the sensitivity studies and first results.

  4. Multi-modal analysis of aerosol robotic network size distributions for remote sensing applications: dominant aerosol type cases

    NASA Astrophysics Data System (ADS)

    Taylor, M.; Kazadzis, S.; Gerasopoulos, E.

    2013-12-01

    To date, size distributions obtained from the aerosol robotic network have been fit with bi-lognormals defined by six secondary microphysical parameters: the volume concentration, effective radius, and the variance of fine and coarse particle modes. However, since the total integrated volume concentration is easily calculated and can be used as an accurate constraint, the problem of fitting the size distribution can be reduced to that of deducing a single free parameter - the mode separation point. We present a method for determining the mode separation point for equivalent-volume bi-lognormal distributions based on optimisation of the root mean squared error and the coefficient of determination. The extracted secondary parameters are compared with those provided by AERONET's Level 2.0 Version 2 inversion algorithm for a set of benchmark dominant aerosol types including: desert dust, biomass burning aerosol, urban sulphate and sea salt. The total volume concentration constraint is then also lifted by performing multi-modal fits to the size distribution using nested Gaussian mixture models and a method is presented for automating the selection of the optimal number of modes using a stopping condition based on Fisher statistics and via the application of statistical hypothesis testing. It is found that the method for optimizing the location of the mode separation point is independent of the shape of the AVSD, does not require the existence of a local minimum in the size interval 0.439 μm ≤ r ≤ 0.992 μm, and shows some potential for optimizing the bi-lognormal fitting procedure used by AERONET particularly in the case of desert dust aerosol. The AVSD of impure marine aerosol is found to require 3 modes. In this particular case, bi-lognormals fail to recover key features of the AVSD. Fitting the AVSD more generally with multi-modal models allows automatic detection of a statistically-significant number of aerosol modes, is applicable to a very diverse range of

  5. Aerosol size distribution and radiative forcing response to anthropogenically driven historical changes in biogenic secondary organic aerosol formation

    NASA Astrophysics Data System (ADS)

    D'Andrea, S. D.; Acosta Navarro, J. C.; Farina, S. C.; Scott, C. E.; Rap, A.; Farmer, D. K.; Spracklen, D. V.; Riipinen, I.; Pierce, J. R.

    2014-10-01

    Emissions of biogenic volatile organic compounds (BVOC) have changed in the past millennium due to changes in land use, temperature and CO2 concentrations. Recent model reconstructions of BVOC emissions over the past millennium predicted changes in dominant secondary organic aerosol (SOA) producing BVOC classes (isoprene, monoterpenes and sesquiterpenes). The reconstructions predicted that global isoprene emissions have decreased (land-use changes to crop/grazing land dominate the reduction), while monoterpene and sesquiterpene emissions have increased (temperature increases dominate the increases); however, all three show regional variability due to competition between the various influencing factors. These BVOC changes have largely been anthropogenic in nature, and land-use change was shown to have the most dramatic effect by decreasing isoprene emissions. In this work, we use two modeled estimates of BVOC emissions from the years 1000 to 2000 to test the effect of anthropogenic changes to BVOC emissions on SOA formation, global aerosol size distributions, and radiative effects using the GEOS-Chem-TOMAS global aerosol microphysics model. With anthropogenic emissions (e.g. SO2, NOx, primary aerosols) held at present day values and BVOC emissions changed from year 1000 to year 2000 values, decreases in the number concentration of particles of size Dp > 80 nm (N80) of >25% in year 2000 relative to year 1000 were predicted in regions with extensive land-use changes since year 1000 which led to regional increases in direct plus indirect aerosol radiative effect of >0.5 W m-2 in these regions. We test the sensitivity of our results to BVOC emissions inventory, SOA yields and the presence of anthropogenic emissions; however, the qualitative response of the model to historic BVOC changes remains the same in all cases. Accounting for these uncertainties, we estimate millennial changes in BVOC emissions cause a global mean direct effect of between +0.022 and +0.163 W m-2

  6. Biogenic, anthropogenic and sea salt sulfate size-segregated aerosols in the Arctic summer

    NASA Astrophysics Data System (ADS)

    Ghahremaninezhad, Roghayeh; Norman, Ann-Lise; Abbatt, Jonathan P. D.; Levasseur, Maurice; Thomas, Jennie L.

    2016-04-01

    Size-segregated aerosol sulfate concentrations were measured on board the Canadian Coast Guard Ship (CCGS) Amundsen in the Arctic during July 2014. The objective of this study was to utilize the isotopic composition of sulfate to address the contribution of anthropogenic and biogenic sources of aerosols to the growth of the different aerosol size fractions in the Arctic atmosphere. Non-sea-salt sulfate is divided into biogenic and anthropogenic sulfate using stable isotope apportionment techniques. A considerable amount of the average sulfate concentration in the fine aerosols with a diameter < 0.49 µm was from biogenic sources (> 63 %), which is higher than in previous Arctic studies measuring above the ocean during fall (< 15 %) (Rempillo et al., 2011) and total aerosol sulfate at higher latitudes at Alert in summer (> 30 %) (Norman et al., 1999). The anthropogenic sulfate concentration was less than that of biogenic sulfate, with potential sources being long-range transport and, more locally, the Amundsen's emissions. Despite attempts to minimize the influence of ship stack emissions, evidence from larger-sized particles demonstrates a contribution from local pollution. A comparison of δ34S values for SO2 and fine aerosols was used to show that gas-to-particle conversion likely occurred during most sampling periods. δ34S values for SO2 and fine aerosols were similar, suggesting the same source for SO2 and aerosol sulfate, except for two samples with a relatively high anthropogenic fraction in particles < 0.49 µm in diameter (15-17 and 17-19 July). The high biogenic fraction of sulfate fine aerosol and similar isotope ratio values of these particles and SO2 emphasize the role of marine organisms (e.g., phytoplankton, algae, bacteria) in the formation of fine particles above the Arctic Ocean during the productive summer months.

  7. [Determination of the retrieval arithmetic of aerosol size distribution measured by DOAS].

    PubMed

    Si, Fu-qi; Xie, Pin-hua; Liu, Jian-guo; Zhang, Yu-jun; Liu, Wen-qing; Hiroaki, Kuze; Nobuo, Takeuchi

    2008-10-01

    Atmospheric aerosol is not only an important factor for the change in global climate, but also a polluting matter. Moreover, aerosol plays a main role in chemical reaction of polluting gases. Determination of aerosol has become an important re- search in the study of atmospheric environment. Differential optical absorption spectroscopy (DOAS) is a very useful technique that allows quantitative measurement of atmospheric trace gas concentrations based on their fingerprint absorption. It also can be used to retrieve aerosol extinction coefficient. In the present work, the method of determination of aerosol size distribution measured by flash DOAS is described, and the arithmetic based on Monte-Carlo is the emphasis. By comparison with the concentration of PM10, visibility and Angstrom wavelength exponent, a good correlation can be found. Application of DOAS in aerosol field not only provides a novel method for aerosol detection, but also extends the field of application of DOAS technology. Especially, aerosol DOAS plays an important role in the study of atmospheric chemistry. PMID:19123420

  8. Aerosol size distribution retrievals from sunphotometer measurements: Theoretical evaluation of errors due to circumsolar and related effects

    NASA Astrophysics Data System (ADS)

    Kocifaj, Miroslav; Gueymard, Christian A.

    2012-05-01

    The uncertainty in particle size distribution retrievals is analyzed theoretically and numerically when using aerosol optical depth (AOD) data affected by three distinct error-inducing effects. Specifically, circumsolar radiation (CS), optical mass (OM), and solar disk's brightness distribution (BD) effects are taken into consideration here. Because of these effects, the theoretical AOD is affected by an error, ∂AOD, that consequently translates into errors in the determined (apparent) particle size distribution (PSD). Through comparison of the apparent and the true size distributions, the relative error, ∂PSD, is calculated here as a function of particle radius for various instrument's fields of view (aperture) and solar zenith angles. It is shown that, in general, the CS effect overestimates the number of submicron-sized particles, and that the significance of this effect increases with the aperture. In case of maritime aerosols, the CS effect may also lead to an underestimation of the number concentration of large micron-sized particles. The BD and OM effects become important, and possibly predominant, when AOD is low. Assuming large particles dominate in the atmosphere, the BD effect tends to underestimate the concentration of the smallest aerosol particles. In general, the PSD(apparent)/PSD(true) ratio is affected by the CS effect equally over all particle sizes. The relative errors in PSD are typically smaller than 40-60%, but can exceptionally exceed 100%, which means that the apparent PSD may then be twice as large as the true PSD. This extreme situation typically occurs with maritime aerosols under elevated humidity conditions. Recent instruments tend to be designed with smaller apertures than ever before, which lower the CS-induced errors to an acceptable level in most cases.

  9. Stratospheric aerosol particle size information in Odin-OSIRIS limb scatter spectra

    NASA Astrophysics Data System (ADS)

    Rieger, L. A.; Bourassa, A. E.; Degenstein, D. A.

    2014-02-01

    The Optical Spectrograph and InfraRed Imaging System (OSIRIS) onboard the Odin satellite has now taken over a decade of limb scatter measurements that have been used to retrieve the version 5 stratospheric aerosol extinction product. This product is retrieved using a representative particle size distribution to calculate scattering cross sections and scattering phase functions for the forward model calculations. In this work the information content of OSIRIS measurements with respect to stratospheric aerosol is systematically examined for the purpose of retrieving particle size information along with the extinction coefficient. The benefit of using measurements at different wavelengths and scattering angles in the retrieval is studied, and it is found that incorporation of the 1530 nm radiance measurement is key for a robust retrieval of particle size information. It is also found that using OSIRIS measurements at the different solar geometries available on the Odin orbit simultaneously provides little additional benefit. Based on these results, an improved aerosol retrieval algorithm is developed that couples the retrieval of aerosol extinction and mode radius of a log-normal particle size distribution. Comparison of these results with coincident measurements from SAGE III shows agreement in retrieved extinction to within approximately 10% over the bulk of the aerosol layer, which is comparable to version 5. The retrieved particle size, when converted to Ångström coefficient, shows good qualitative agreement with SAGE II measurements made at somewhat shorter wavelengths.

  10. Aerosol Size Distribution Determined From Multiple Field-Of-View Lidar

    NASA Astrophysics Data System (ADS)

    Liu, Y.; Yabuki, M.; Tsuda, T.; Uesugi, T.

    2014-12-01

    Knowledge of aerosol size distribution is essential for its influence on atmosphere and human health, especially for small particles because they are able to penetrate lung tissues, thus increasing the risk of bronchitis or lung diseases. Lidar as an active optical remote sensing technique is effective for monitoring aerosols with high temporal and spatial variations. Particles with diameters comparable to the detecting light wavelength have been effectively detected by using UV, VIS, and near-IR wavelengths. However, to quantitatively estimate the shape of the particle size distribution, more information is required with respect to sub-micrometer and smaller particles. Conventional lidar employs tiny field-of-view (FOV) to detect single scatter reflected from aerosols in the direction opposite to incident light. However, the complicated reflection on the path of laser causes multiple scatter which contains also the size distribution information of aerosols. In this study, a UV Lidar with multiple FOV receiver was used for detecting such multiple scattering effects in order to obtain more quantitative information related to particle size distribution. The FOV of Lidar receiver was program controlled in a range from 0.1 mrad to 12.4 mrad. The pacific retrieval method for aerosol size distribution using this feature and field measurement results will be introduced in the presentation.

  11. Effect of aerosol particle size on bronchodilatation with nebulised terbutaline in asthmatic subjects.

    PubMed

    Clay, M M; Pavia, D; Clarke, S W

    1986-05-01

    The bronchodilatation achieved by the beta 2 agonist terbutaline sulphate given as nebulised aerosol from different devices has been measured in seven patients with mild asthma (mean FEV1 76% predicted) over two hours after inhalation. The subjects were studied on four occasions. On three visits they received 2.5 mg terbutaline delivered from three different types of nebuliser, selected on the basis of the size distribution of the aerosols generated; and on a fourth (control) visit no aerosol was given. The size distributions of the aerosols expressed in terms of their mass median diameter (MMD) were: A: MMD 1.8 microns; B: 4.6 microns; C: 10.3 microns. The aerosols were given under controlled conditions of respiratory rate and tidal volume to minimise intertreatment variation. Bronchodilator response was assessed by changes in FEV1, forced vital capacity (FVC), peak expiratory flow (PEF), and maximal flow after expiration of 50% and 75% FVC (Vmax50, Vmax25) from baseline (before aerosol) and control run values. For each pulmonary function index all three aerosols gave significantly better improvement over baseline than was seen in the control (p less than 0.05) and had an equipotent effect on FEV1, FVC, and PEF. Aerosol A (MMD 1.8 microns) produced significantly greater improvements in Vmax50 and Vmax25 than did B or C (p less than 0.05). These results suggest that for beta 2 agonists small aerosols (MMD less than 2 microns) might be advantageous in the treatment of asthma. PMID:3750243

  12. The Dependence of Cloud Particle Size on Non-Aerosol-Loading Related Variables

    SciTech Connect

    Shao, H.; Liu, G.

    2005-03-18

    An enhanced concentration of aerosol may increase the number of cloud drops by providing more cloud condensation nuclei (CCN), which in turn results in a higher cloud albedo at a constant cloud liquid water path. This process is often referred to as the aerosol indirect effect (AIE). Many in situ and remote sensing observations support this hypothesis (Ramanathan et al. 2001). However, satellite observed relations between aerosol concentration and cloud drop size are not always in agreement with the AIE. Based on global analysis of cloud effective radius (r{sub e}) and aerosol number concentration (N{sub a}) derived from satellite data, Sekiguchi et al. (2003) found that the correlations between the two variables can be either negative, or positive, or none, depending on the location of the clouds. They discovered that significantly negative r{sub e} - N{sub a} correlation can only be identified along coastal regions of the continents where abundant continental aerosols inflow from land, whereas Feingold et al. (2001) found that the response of r{sub e} to aerosol loading is the greatest in the region where aerosol optical depth ({tau}{sub a}) is the smallest. The reason for the discrepancy is likely due to the variations in cloud macroscopic properties such as geometrical thickness (Brenguier et al. 2003). Since r{sub e} is modified not only by aerosol but also by cloud geometrical thickness (H), the correlation between re and {tau}{sub a} actually reflects both the aerosol indirect effect and dependence of H. Therefore, discussing AIE based on the r{sub e}-{tau}{sub a} correlation without taking into account variations in cloud geometrical thickness may be misleading. This paper is motivated to extract aerosols' effect from overall effects using the independent measurements of cloud geometrical thickness, {tau}{sub a} and r{sub e}.

  13. Aerosol size distribution, composition, and CO sub 2 backscatter at Mauna Loa Observatory

    SciTech Connect

    Clarke, A.D.; Porter, J.N. )

    1991-03-20

    Continuous measurements of aerosol size distributions were obtained during Jan-Mar and Nov-Dec periods of 1988 at Mauna Loa Observatory, Hawaii. These periods were chosen in order to characterize aerosol physiochemistry during periods representative of low-dust atmospheric conditions and periods associated with appreciable Asian dust transport to that site. Size distributions for particles with diameters between 0.15 and 7.6 {mu}m were accumulated in 256 size bins of a laser optical particle counter for 3-hour intervals during most of the period. The aerosol sample stream was heated to selected temperatures in order to provide size-discriminated measurements of aerosol volatility. Resulting data were used to assess the variability in aerosol concentrations and properties related to aerosol backscatter values at a wavelength of 10.6 {mu}m, {beta}{sub CO{sub 2}}, in the mid-troposphere. Low aerosol concentrations, considered representative of mid-tropospheric air, occurred in downslope flow between midnight and sunrise. Measurements for these time periods suggest that {beta}{sub CO{sub 2}} varied from a low of about 5 {times} 10{sup {minus}12}m{sup {minus}1}sr{sup {minus}1} to a high of 5 {times} 10{sup {minus}8}m{sup {minus}1}sr{sup {minus}1}. Coarse particles with diameters between 1.0 and 5.0 {mu}m account for most of the derived values of {beta}{sub CO{sub 2}} at all but the highest and lowest aerosol mass concentrations. Volatile aerosol appears to dominate aerosol mass during the cleanest periods but was a small fraction of the total during dust events. The authors estimate that minimum values for {beta}{sub CO{sub 2}} at about 8 km should usually fall in the range of 1-3 {times} 10{sup {minus}12}m{sup {minus}1}sr{sup {minus}1} and be dominated by a sulfate aerosol.

  14. MULTI-TECHNIQUE APPROACH TO MEASURE SIZE AND TIME RESOLVED ATMOSPHERIC AND RADIONUCLIDE AEROSOLS

    SciTech Connect

    Shutthanandan, V; Xie, YuLong; Disselkamp, Robert S; Laulainen, Nels S; Smith, Edward A; Thevuthasan, Suntharampillai

    2008-12-01

    Accurate quantifications of aerosol components are crucial to predict global atmospheric transport models. Recently developed International Monitoring System (IMS) network represents an opportunity to enhance comprehensive systematic aerosol observations on a global scale because it provides a global infrastructure. As such, a local pilot study utilizing several state-of-the-art instruments has been conducted at the peak of Rattlesnake Mountain, Washington, USA, during three month periods (June-August) in 2003 to explore this opportunity. In this study, routine aerosol samples were collected using a 3-stage Cascade Impactor Beam Analyzer (0.07 to 2.5 µm) with time resolution about 6 hours on long Teflon strips while radionuclide aerosols were collected using Radionuclide aerosol sampler/analyzer (RASA) developed at Pacific Northwest National Laboratory. The elemental composition and hydrogen concentration were measured using proton induced x-ray emission (PIXE) and proton elastic scattering analysis (PESA), respectively. In addition, short and long-lived radionuclides that exist in nature were measured with same time resolution (6 hours) using RASA. In this method, high-resolution gamma-ray spectra were analyzed for radionuclide concentration. Combination of trace radioactive and non-radioactive element analysis in aerosols makes this investigation unique.

  15. Aerosol size distribution variability as a function of distance to Caribbean Trade Wind Cumulus Clouds

    NASA Astrophysics Data System (ADS)

    Colon-Robles, M.; Rauber, R.; di Girolamo, L.; Jensen, J. B.

    2009-12-01

    Shallow maritime cumuli continually modify aerosol size distributions in the trade wind regime, which leads to sampling problems due to this continual aerosol-cloud interaction. Because of the ubiquity of trade wind clouds across the world’s tropical oceans, understanding the relationship between trade wind cumuli and aerosol spectra in the trade wind layer is required to evaluate the role of aerosols in Earth's radiation balance and climate. Studies in the past typically select either cloudy or cloud free areas to obtain aerosol size distributions. However, conclusions of past studies point to the fact that distance to cloud is an important parameter to consider when reporting aerosol size distributions. In this work, data collected from the National Center for Atmospheric Research Hercules C-130 during the Rain in Cumulus over the Ocean (RICO) field campaign, which took place during November 2004 - January 2005 in the trades over the western Atlantic, is used to study the variations of deliquesced and dry particle size distributions of sub-micron (dry radius, r = 0.05 - 1.0 μm) and giant (1 < r ≤ 10 μm) particles as function of distance to cloud and altitude above the ocean surface. Data collected from 13 research flights using aircraft mounted probes, PCASP/SPP-200 and FSSP/SPP-100, are used to obtain variations in particle spectra as a function of distance to cloud between 600m and 2000m above the ocean surface. Statistical summaries of the aerosol characteristics of the trade wind environment in the vicinity of clouds observed during RICO will be presented.

  16. On the validity of the Poisson assumption in sampling nanometer-sized aerosols

    SciTech Connect

    Damit, Brian E; Wu, Dr. Chang-Yu; Cheng, Mengdawn

    2014-01-01

    A Poisson process is traditionally believed to apply to the sampling of aerosols. For a constant aerosol concentration, it is assumed that a Poisson process describes the fluctuation in the measured concentration because aerosols are stochastically distributed in space. Recent studies, however, have shown that sampling of micrometer-sized aerosols has non-Poissonian behavior with positive correlations. The validity of the Poisson assumption for nanometer-sized aerosols has not been examined and thus was tested in this study. Its validity was tested for four particle sizes - 10 nm, 25 nm, 50 nm and 100 nm - by sampling from indoor air with a DMA- CPC setup to obtain a time series of particle counts. Five metrics were calculated from the data: pair-correlation function (PCF), time-averaged PCF, coefficient of variation, probability of measuring a concentration at least 25% greater than average, and posterior distributions from Bayesian inference. To identify departures from Poissonian behavior, these metrics were also calculated for 1,000 computer-generated Poisson time series with the same mean as the experimental data. For nearly all comparisons, the experimental data fell within the range of 80% of the Poisson-simulation values. Essentially, the metrics for the experimental data were indistinguishable from a simulated Poisson process. The greater influence of Brownian motion for nanometer-sized aerosols may explain the Poissonian behavior observed for smaller aerosols. Although the Poisson assumption was found to be valid in this study, it must be carefully applied as the results here do not definitively prove applicability in all sampling situations.

  17. Tropospheric aerosols: size-differentiated chemistry and large-scale spatial distributions.

    PubMed

    Hidy, George M; Mohnen, Volker; Blanchard, Charles L

    2013-04-01

    Worldwide interest in atmospheric aerosols has emerged since the late 20th century as a part of concerns for air pollution and radiative forcing of the earth's climate. The use of aircraft and balloons for sampling and the use of remote sensing have dramatically expanded knowledge about tropospheric aerosols. Our survey gives an overview of contemporary tropospheric aerosol chemistry based mainly on in situ measurements. It focuses on fine particles less than 1-2.5 microm in diameter. The physical properties of particles by region and altitude are exemplified by particle size distributions, total number and volume concentration, and optical parameters such as extinction coefficient and aerosol optical depth. Particle chemical characterization is size dependent, differentiated by ubiquitous sulfate, and carbon, partially from anthropogenic activity. Large-scale particle distributions extend to intra- and intercontinental proportions involving plumes from population centers to natural disturbances such as dust storms and vegetation fires. In the marine environment, sea salt adds an important component to aerosols. Generally, aerosol components, most of whose sources are at the earth's surface, tend to dilute and decrease in concentration with height, but often show different (layered) profiles depending on meteorological conditions. Key microscopic processes include new particle formation aloft and cloud interactions, both cloud initiation and cloud evaporation. Measurement campaigns aloft are short term, giving snapshots of inherently transient phenomena in the troposphere. Nevertheless, these data, combined with long-term data at the surface and optical depth and transmission observations, yield a unique picture of global tropospheric particle chemistry. PMID:23687724

  18. Aerosol size distribution characteristics of organosulfates in the Pearl River Delta region, China

    NASA Astrophysics Data System (ADS)

    Kuang, Bin Yu; Lin, Peng; Hu, Min; Yu, Jian Zhen

    2016-04-01

    Organosulfates (OSs) have been detected in various atmospheric environments, but their particle size distribution characteristics are unknown. In this work, we examined their size distributions in ambient aerosols to gain insights into the formation processes. Size-segregated aerosol samples in the range of 0.056-18 μm were collected using a ten-stage impactor at a receptor site in Hong Kong in both summer and winter and in Nansha in the Pearl River Delta in winter. The humic-like substances fraction in the size-segregated samples was isolated and analyzed using electrospray ionization coupled with an Orbitrap Ultra High Resolution Mass Spectrometer. Through accurate mass measurements, ∼190 CHOS and ∼90 CHONS formulas were tentatively identified to be OS compounds. Among them, OS compounds derived from isoprene, α-/β-pinene, and limonene and alkyl OSs having low double bond equivalents (DBE = 0,1) and 0-2 extra O beyond those in -OSO3 were found with high intensity. The biogenic volatile organic compounds-derived OS formulas share a common characteristic with sulfate in that the droplet mode dominated, peaking in either 0.56-1.0 or 1.0-1.8 μm size bin, reflecting sulfate as their common precursor. Most of these OSs have a minor coarse mode, accounting for 0-45%. The presence of OSs on the coarse particles is hypothesized to be a result of OSs on small particle (<0.32 μm) coagulating with coarse particles, as the abundance ratios of OS to non-sea-salt sulfate present on the coarse particles were similar to those on particles <0.32 μm. Among a few pairs of CHONS and CHOS that could be linked up through hydrolysis of a nitrooxy group in the CHONS form (e.g., m/z 294: C10H16O7NS- vs. m/z 249 C10H17O5S- from α/β-pinene, differing by (+H2O-HNO3)), the CHONS compounds had an enhanced coarse mode presence. This could be interpreted as a result of slower hydrolysis of the CHONS compounds on the alkali coarse particles. The low DBE alkyl OS compounds have a

  19. PARTICLE SIZE DISTRIBUTION OF NITRATE AEROSOLS IN THE LOS ANGELES AIR BASIN

    EPA Science Inventory

    The atmospheric aerosol was sampled with a low pressure impactor at a coastal, an urban, and an agricultural site in the Los Angeles air basin. The material collected on each stage was analyzed for nitrate by direct vaporization into a chemiluminescent analyzer, sensitive at nano...

  20. Organic Composition of Size-Segregated Aerosols Sampled During the 2002 Bay Regional Atmospheric Chemistry Experiment (BRACE), Florida, USA

    NASA Astrophysics Data System (ADS)

    Tremblay, R. T.; Zika, R. G.

    2003-04-01

    Aerosol samples were collected for the analysis of organic source markers using non-rotating Micro Orifice Uniform Deposit Impactors (MOUDI) as part of the Bay Regional Atmospheric Chemistry Experiment (BRACE) in Tampa, FL, USA. Daily samples were collected 12 m above ground at a flow rate of 30 lpm throughout the month of May 2002. Aluminum foil discs were used to sample aerosol size fractions with aerodynamic cut diameter of 18, 10, 5.6, 3.2, 1.8, 1.0, 0.56, 0.32, 0.17 and 0.093 um. Samples were solvent extracted using a mixture of dichloromethane/acetone/hexane, concentrated and then analyzed using gas chromatography-mass spectrometry (GC/MS). Low detection limits were achieved using a HP Programmable Temperature Vaporizing inlet (PTV) and large volume injections (80ul). Excellent chromatographic resolution was obtained using a 60 m long RTX-5MS, 0.25 mm I.D. column. A quantification method was built for over 90 organic compounds chosen as source markers including straight/iso/anteiso alkanes and polycyclic aromatic hydrocarbons (PAH). The investigation of potential aerosol sources for different particle sizes using known organic markers and source profiles will be presented. Size distributions of carbon preference indices (CPI), percent wax n-alkanes (%WNA) and concentration of selected compounds will be discussed. Also, results will be compared with samples acquired in different environments including the 1999 Atlanta SuperSite Experiment, GA, USA.

  1. Analyzing signatures of aerosol-cloud interactions from satelliteretrievals and the GISS GCM to constrain the aerosol indirecteffect

    SciTech Connect

    Menon, S.; Del Genio, A.D.; Kaufman, Y.; Bennartz, R.; Koch, D.; Loeb, N.; Orlikowski, D.

    2007-10-01

    Evidence of aerosol-cloud interactions are evaluated using satellite data from MODIS, CERES, AMSR-E, reanalysis data from NCEP and data from the NASA Goddard Institute for Space Studies climate model. We evaluate a series of model simulations: (1) Exp N- aerosol direct radiative effects; (2) Exp C- Like Exp N but with aerosol effects on liquid-phase cumulus and stratus clouds; (3) Exp CN- Like Exp C but with model wind fields nudged to reanalysis data. Comparison between satellite-retrieved data and model simulations for June to August 2002, over the Atlantic Ocean indicate the following: a negative correlation between aerosol optical thickness (AOT) and cloud droplet effective radius (R{sub eff}) for all cases and satellite data, except for Exp N; a weak but negative correlation between liquid water path (LWP) and AOT for MODIS and CERES; and a robust increase in cloud cover with AOT for both MODIS and CERES. In all simulations, there is a positive correlation between AOT and both cloud cover and LWP (except in the case of LWP-AOT for Exp CN). The largest slopes are obtained for Exp N, implying that meteorological variability may be an important factor. The main fields associated with AOT variability in NCEP/MODIS data are warmer temperatures and increased subsidence for less clean cases, not well captured by the model. Simulated cloud fields compared with an enhanced data product from MODIS and AMSR-E indicate that model cloud thickness is over-predicted and cloud droplet number is within retrieval uncertainties. Since LWP fields are comparable this implies an under-prediction of R{sub eff} and thus an over-prediction of the indirect effect.

  2. Fast Airborne Aerosol Size and Chemistry Measurements with the High Resolution Aerosol Mass Spectrometer during the MILAGRO Campaign

    NASA Technical Reports Server (NTRS)

    DeCarlo, P. F.; Dunlea, E. J.; Kimmel, J. R.; Aiken, A. C.; Sueper, D.; Crounse, J.; Wennberg, P. O.; Emmons, L.; Shinozuka, Y.; Clarke, A.; Zhou, J.; Tomlinson, J.; Collins,D. R.; Knapp, D.; Weinheimer, A. J.; Montzka,D. D.; Campos,T.; Jimenez, J. L.

    2007-01-01

    The concentration, size, and composition of non-refractory submicron aerosol (NR-PM(sub l)) was measured over Mexico City and central Mexico with a High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) onboard the NSF/NCAR C-130 aircraft as part of the MILAGRO field campaign. This was the first aircraft deployment of the HR-ToF-AMS. During the campaign the instrument performed very well, and provided 12 s data. The aerosol mass from the AMS correlates strongly with other aerosol measurements on board the aircraft. Organic aerosol (OA) species dominate the NR-PM(sub l) mass. OA correlates strongly with CO and HCN indicating that pollution (mostly secondary OA, SOA) and biomass burning (BB) are the main OA sources. The OA to CO ratio indicates a typical value for aged air of around 80 microg/cubic m (STP) ppm(exp -1). This is within the range observed in outflow from the Northeastern US, which could be due to a compensating effect between higher BB but lower biogenic VOC emissions during this study. The O/C atomic ratio for OA is calculated from the HR mass spectra and shows a clear increase with photochemical age, as SOA forms rapidly and quickly overwhelms primary urban OA, consistent with Volkamer et al. (2006) and Kleinman et al. (2008). The stability of the OA/CO while O/C increases with photochemical age implies a net loss of carbon from the OA. BB OA is marked by signals at m/z 60 and 73, and also by a signal enhancement at large m/z indicative of larger molecules or more resistance to fragmentation. The main inorganic components show different spatial patterns and size distributions. Sulfate is regional in nature with clear volcanic and petrochemical/power plant sources, while the urban area is not a major regional source for this species. Nitrate is enhanced significantly in the urban area and immediate outflow, and is strongly correlated with CO indicating a strong urban source. The importance of nitrate decreases with distance from the city

  3. Aerosol number size distributions over a coastal semi urban location: Seasonal changes and ultrafine particle bursts.

    PubMed

    Babu, S Suresh; Kompalli, Sobhan Kumar; Moorthy, K Krishna

    2016-09-01

    Number-size distribution is one of the important microphysical properties of atmospheric aerosols that influence aerosol life cycle, aerosol-radiation interaction as well as aerosol-cloud interactions. Making use of one-yearlong measurements of aerosol particle number-size distributions (PNSD) over a broad size spectrum (~15-15,000nm) from a tropical coastal semi-urban location-Trivandrum (Thiruvananthapuram), the size characteristics, their seasonality and response to mesoscale and synoptic scale meteorology are examined. While the accumulation mode contributed mostly to the annual mean concentration, ultrafine particles (having diameter <100nm) contributed as much as 45% to the total concentration, and thus constitute a strong reservoir, that would add to the larger particles through size transformation. The size distributions were, in general, bimodal with well-defined modes in the accumulation and coarse regimes, with mode diameters lying in the range 141 to 167nm and 1150 to 1760nm respectively, in different seasons. Despite the contribution of the coarse sized particles to the total number concentration being meager, they contributed significantly to the surface area and volume, especially during transport of marine air mass highlighting the role of synoptic air mass changes. Significant diurnal variation occurred in the number concentrations, geometric mean diameters, which is mostly attributed to the dynamics of the local coastal atmospheric boundary layer and the effect of mesoscale land/sea breeze circulation. Bursts of ultrafine particles (UFP) occurred quite frequently, apparently during periods of land-sea breeze transitions, caused by the strong mixing of precursor-rich urban air mass with the cleaner marine air mass; the resulting turbulence along with boundary layer dynamics aiding the nucleation. These ex-situ particles were observed at the surface due to the transport associated with boundary layer dynamics. The particle growth rates from

  4. Aerosol mobility imaging for rapid size distribution measurements

    DOEpatents

    Wang, Jian; Hering, Susanne Vera; Spielman, Steven Russel; Kuang, Chongai

    2016-07-19

    A parallel plate dimensional electrical mobility separator and laminar flow water condensation provide rapid, mobility-based particle sizing at concentrations typical of the remote atmosphere. Particles are separated spatially within the electrical mobility separator, enlarged through water condensation, and imaged onto a CCD array. The mobility separation distributes particles in accordance with their size. The condensation enlarges size-separated particles by water condensation while they are still within the gap of the mobility drift tube. Once enlarged the particles are illuminated by a laser. At a pre-selected frequency, typically 10 Hz, the position of all of the individual particles illuminated by the laser are captured by CCD camera. This instantly records the particle number concentration at each position. Because the position is directly related to the particle size (or mobility), the particle size spectra is derived from the images recorded by the CCD.

  5. An Investigation of Size-Dependent Concentration of Trace Elements in Aerosols Emitted from the Oil-Fired Heating Plants

    NASA Technical Reports Server (NTRS)

    Singh, J. J.; Sentell, R. J.; Khandelwal, G. S.

    1976-01-01

    Aerosols emitted from two oil-fired heating plants were aerodynamically separated into eight size groups and were analyzed using the photon-induced X-ray emission (PIXE) technique. It was found that Zn, Mo, Ag, and Pb, and (to a lesser extent) Cd, have a tendency to concentrate preferentially on the smaller aerosols. All of these elements, in certain chemical forms, are known to be toxic. Zinc and molybdenum, although present in low concentrations in the parent fuels, show the strongest tendencies to be concentrated in finer aerosols. Selenium, previously reported to show a very strong tendency to concentration in finer fly ash from coal-fired power plants shows little preference for surface residence. Vanadium, which occurs in significant concentration in the oil fuels for both plants, also shows little preference for surface concentration. Even though the absolute concentrations of the toxic elements involved are well below the safety levels established by the National Institute for Occupational Safety and Health (NIOSH), it would be advisable to raise the heights of the heating-plant exhaust chimneys well above the neighborhood buildings to insure more efficient aerosol dispersal.

  6. Seasonal Variation of Aerosol Particle Size Using MER/Pancam Sky Imaging

    NASA Astrophysics Data System (ADS)

    Smith, M. D.; Wolff, M. J.

    2013-12-01

    Imaging of the sky taken by the Pancam cameras on-board the Mars Exploration Rovers (MER) provide a useful tool for determining the optical depth and physcial properties of aerosols above the rover. Specifically, the brightness of the sky as a function of angle away from the Sun provides a powerful constraint on the size distribution and shape of dust and water ice aerosols. More than 100 Pancam "sky surveys" were taken by each of the two MER rovers covering a time span of several Mars years and a wide range of dust loading conditions including the planet-encirclind dust storm during Mars Year 28 (Earth year 2007). These sky surveys enable the time evolution of aerosol particle size to be determined including its relation to dust loading. Radiative transfer modeling is used to model the observations. Synthetic Pancam sky brightness is computed using a discrete-ordinates radiative transfer code that accounts for multiple scattering from aerosols and spherical geometry by integrating the source functions along curved paths in that coordinate system. We find that Mie scattering from spheres is not a good approximation for describing the angular variation of sky brightness far from the Sun (at scattering angles greater than 45 degrees). Significant seasonal variations are seen in the retrieved effective radius of the aerosols with higher optical depth strongly correlated with larger particle size.

  7. Size-spectra of trace elements in urban aerosol particles by instrumental neutron activation analysis

    SciTech Connect

    Ondov, J.M.; Divita, F. Jr.; Suarez, A.

    1994-12-31

    Knowledge of composition and size of atmospheric aerosol particles is needed to elucidate their sources, atmospheric transformation processes, contributions to visibility reduction, and respiratory and environmental deposition. In a previous communication, we described size spectra and hygroscopic growth of arsenic, selenium, antimony, and zinc in College Park, Maryland, an urban, nonindustrial area located near Washington, D.C., wherein, concentrations of these elements are influenced largely by sulfate-containing aerosol transported from the Ohio River valley region, more than 200 km west of the area, and local coal utility plants and incinerators located 20 to 50 km from the sampling site. At College Park, mass median aerodynamic diameters (mmad) versus relative humidity (RH) data for these elements fell along different curves for samples influenced by local and distant aerosols; i.e., the curve for distant sources lay below the curve for local sources, at larger mmads for the same RH. In this paper we discuss size spectra, distribution parameters, and hygroscopic growth of aerosol particles bearing trace elements in aerosol collected in Camden, New Jersey, a heavily industrial area in which major sources, including an antimony roaster and municipal incinerator, lie in close proximity (i.e., 5 to 15 km) to the site.

  8. Modal characteristics of carbonaceous aerosol size distribution in an urban atmosphere of South China

    NASA Astrophysics Data System (ADS)

    Lan, Zi-Juan; Chen, Dong-Lei; Li, Xiang; Huang, Xiao-Feng; He, Ling-Yan; Deng, Yan-Ge; Feng, Ning; Hu, Min

    2011-04-01

    Size distributions can provide important information about aerosol sources, formation, and growth mechanisms. However, compared to size distributions of inorganic aerosols, size distributions of carbonaceous aerosols have been much less studied and reported in the literature. In this paper, we systematically measured size distributions of elemental carbon (EC), organic carbon (OC), oxalate, polycyclic aromatic hydrocarbons (PAHs), as well as major inorganic ions in urban aerosols in Shenzhen, China. Totally 24 sets of samples were collected using a ten-stage micro orifice uniform deposit impactor (MOUDI) during October 2009 to February 2010. Three lognormal modes contained in the size distributions of species were resolved based on positive matrix factorization (PMF) analysis of the measured dataset, corresponding to the condensation (peak = 0.34 μm), droplet (peak = 0.84 μm), and coarse (peak = 5.4 μm) modes, respectively. The mean concentrations of EC in the condensation, droplet, and coarse modes were 2.20, 1.18, and 0.64 μg m -3, respectively, and the modal characteristics of EC indicate that fresher local combustion emissions contributed mostly to aerosol EC in the urban atmosphere of Shenzhen. The mean concentrations of OC in the condensation, droplet, and coarse modes were 2.29, 3.34, and 3.51 μg m -3, respectively, and the modal characteristics of OC indicate that its sources were more primary in the condensation mode while more secondary in the droplet mode. The modal characteristics of aerosol oxalate and PAHs suggest that they were predominantly from in-cloud secondary formation and local emissions, respectively.

  9. A sea-state based source function for size and composition resolved marine aerosol

    SciTech Connect

    Long, Michael S; Keene, William C; Erickson III, David J

    2011-01-01

    A parameterization for the size- and composition-resolved production fluxes of nascent marine aerosol was developed from prior experimental observations and extrapolated to ambient conditions based on estimates of air entrainment by the breaking of wind-driven ocean waves. Production of particulate organic carbon (OC{sub aer}) was parameterized based on Langmuir equilibrium-type association of organic matter to bubble plumes in seawater and resulting aerosol as constrained by measurements of aerosol produced from productive and oligotrophic seawater. This novel approach is the first to parameterize size- and composition-resolved aerosol production based on explicit evaluation of wind-driven air entrainment/detrainment fluxes and chlorophyll-a as a proxy for surfactants in surface seawater. Production fluxes were simulated globally with an eight aerosol-size-bin version of the NCAR Community Atmosphere Model (CAM v3.5.07). Simulated production fluxes fell within the range of published estimates based on observationally constrained parameterizations. Because the parameterization does not consider contributions from spume drops, the simulated global mass flux (1.5 x 10{sup 3} Tg y{sup -1}) is near the lower end of published estimates. The simulated production of aerosol number (1.4 x 10{sup 6} m{sup -2} s{sup -1}) and OC{sub aer} (29 Tg C y{sup -1}) fall near the upper end of published estimates and suggest that primary marine aerosols may have greater influences on the physicochemical evolution of the troposphere, radiative transfer and climate, and associated feedbacks on the surface ocean than suggested by previous model studies.

  10. Numerical Model to Characterize the Size Increase of Combination Drug and Hygroscopic Excipient Nanoparticle Aerosols

    PubMed Central

    Longest, P. Worth; Hindle, Michael

    2011-01-01

    Enhanced excipient growth is a newly proposed respiratory delivery strategy in which submicrometer or nanometer particles composed of a drug and hygroscopic excipient are delivered to the airways in order to minimize extrathoracic depositional losses and maximize lung retention. The objective of this study was to develop a validated mathematical model of aerosol size increase for hygroscopic excipients and combination excipient-drug particles and to apply this model to characterize growth under typical respiratory conditions. Compared with in vitro experiments, the droplet growth model accurately predicted the size increase of single component and combination drug and excipient particles. For typical respiratory drug delivery conditions, the model showed that droplet size increase could be effectively correlated with the product of a newly defined hygroscopic parameter and initial volume fractions of the drug and excipient in the particle. A series of growth correlations was then developed that successively included the effects of initial drug and excipient mass loadings, initial aerosol size, and aerosol number concentration. Considering EEG delivery, large diameter growth ratios (2.1–4.6) were observed for a range of hygroscopic excipients combined with both hygroscopic and non-hygroscopic drugs. These diameter growth ratios were achieved at excipient mass loadings of 50% and below and at realistic aerosol number concentrations. The developed correlations were then used for specifying the appropriate initial mass loadings of engineered insulin nanoparticles in order to achieve a predetermined size increase while maximizing drug payload and minimizing the amount of hygroscopic excipient. PMID:21804683

  11. Mass size distributions of soluble sulfate, nitrate and ammonium in the Madrid urban aerosol

    NASA Astrophysics Data System (ADS)

    Plaza, J.; Pujadas, M.; Gómez-Moreno, F. J.; Sánchez, M.; Artíñano, B.

    2011-09-01

    This paper analyzes the mass size distribution of some inorganic species present in the atmospheric aerosol from a field campaign carried out in Madrid throughout a complete year (February 2007-February 2008). Samplings were performed by means of a micro-orifice uniform deposit impactor (MOUDI). Ambient air was sampled during consecutive nocturnal and diurnal periods, and diurnal/nocturnal behaviors were compared for the twenty night-day sampling pairs that were gathered. Annual and seasonal averages were obtained, and some case studies under specific atmospheric conditions are discussed in the paper. Results have shown that the sulfate and ammonium mass was concentrated in the accumulation mode, between 0.18 and 0.56 μm, so that gas-phase and condensation processes for secondary aerosol formation prevailed during the sampling periods in this area. An exception to this behavior was found during a fog event when distributions for these two species were centered in the 0.56-1 and 1-1.8 μm size stages, corresponding to the droplet mode. In most of the samples, the ammonium mass measured in these size ranges was enough or almost enough to neutralize inorganic acidity by formation of ammonium sulfate and nitrate. However, a significant sulfate mass not neutralized by ammonium was found in the impactor backup quartz filter (aerodynamic diameter < 0.056 μm). The concentration of this sulfate and its contribution to the ultrafine fraction mass was higher under good dispersive conditions, prevailing in summer, when particle growth processes are not so favored due to the higher atmospheric dilution factors. The origin of this ultrafine sulfate has been attributed to direct emissions from traffic, associated to the nucleation mode. Regarding the nitrate concentration, it was found higher in the coarse mode than in the accumulation mode on an annual basis. The highest concentrations were measured in winter episodic situations. The marked seasonal variability shown in the

  12. Processes controlling the annual cycle of Arctic aerosol number and size distributions

    NASA Astrophysics Data System (ADS)

    Croft, Betty; Martin, Randall V.; Leaitch, W. Richard; Tunved, Peter; Breider, Thomas J.; D'Andrea, Stephen D.; Pierce, Jeffrey R.

    2016-03-01

    Measurements at high-Arctic sites (Alert, Nunavut, and Mt. Zeppelin, Svalbard) during the years 2011 to 2013 show a strong and similar annual cycle in aerosol number and size distributions. Each year at both sites, the number of aerosols with diameters larger than 20 nm exhibits a minimum in October and two maxima, one in spring associated with a dominant accumulation mode (particles 100 to 500 nm in diameter) and a second in summer associated with a dominant Aitken mode (particles 20 to 100 nm in diameter). Seasonal-mean aerosol effective diameter from measurements ranges from about 180 in summer to 260 nm in winter. This study interprets these annual cycles with the GEOS-Chem-TOMAS global aerosol microphysics model. Important roles are documented for several processes (new-particle formation, coagulation scavenging in clouds, scavenging by precipitation, and transport) in controlling the annual cycle in Arctic aerosol number and size. Our simulations suggest that coagulation scavenging of interstitial aerosols in clouds by aerosols that have activated to form cloud droplets strongly limits the total number of particles with diameters less than 200 nm throughout the year. We find that the minimum in total particle number in October can be explained by diminishing new-particle formation within the Arctic, limited transport of pollution from lower latitudes, and efficient wet removal. Our simulations indicate that the summertime-dominant Aitken mode is associated with efficient wet removal of accumulation-mode aerosols, which limits the condensation sink for condensable vapours. This in turn promotes new-particle formation and growth. The dominant accumulation mode during spring is associated with build up of transported pollution from outside the Arctic coupled with less-efficient wet-removal processes at colder temperatures. We recommend further attention to the key processes of new-particle formation, interstitial coagulation, and wet removal and their delicate

  13. Size-Limited Penetration of Nanoparticles into Porcine Respiratory Mucus after Aerosol Deposition.

    PubMed

    Murgia, Xabier; Pawelzyk, Paul; Schaefer, Ulrich F; Wagner, Christian; Willenbacher, Norbert; Lehr, Claus-Michael

    2016-04-11

    We investigated the rheological properties and the penetration of differently sized carboxylated nanoparticles in pig pulmonary mucus, on different distance and time scales. Nanoparticles were either mechanically mixed into the mucus samples or deposited as an aerosol, the latter resembling a more physiologically relevant delivery scenario. After mechanical dispersion, 500 nm particles were locally trapped; a fraction of carboxylated tracer particles of 100 or 200 nm in diameter could however freely diffuse in these networks over distances of approximately 20 μm. In contrast, after aerosol deposition on top of the mucus layer only particles with a size of 100 nm were able to penetrate into mucus, suggesting the presence of smaller pores at the air-mucus interface compared to within mucus. These findings are relevant to an understanding of the fate of potentially harmful aerosol particles, such as pathogens, pollutants, and other nanomaterials after incidental inhalation, as well as for the design of pulmonary drug delivery systems. PMID:26957140

  14. Activity size distribution and residence time of 7Be aerosols in the Arctic atmosphere

    NASA Astrophysics Data System (ADS)

    Ioannidou, Alexandra; Paatero, Jussi

    2014-05-01

    The activity size distributions of the natural radionuclide tracer 7Be in different size range fractions (<0.39 μm, 0.39-0.69 μm, 0.69-1.3 μm, 1.3-2.1 μm, 2.1-4.2 μm, 4.2-10.2 μm and >10.2 μm) were determined in the boreal atmosphere in the Arctic Research Centre of the Finnish Meteorological Institute (FMI) at Sodankylä, Finland (67°22‧ N, 26°38‧ E, 180 m asl). The activity median aerodynamic diameter (AMAD) ranged from 0.54 μm to 1.05 μm (average 0.83 μm). A residence time of about 8 days applies to aerosols of 0.83 μm diameter, representing the residence of aerosol particles in arctic environment. The observed positive correlation between AMAD values and RH% can be explained by the fact that condensation during high relative humidity conditions becomes more intense, resulting in increased particle sizes of atmospheric aerosols. However, greater aerosol particle sizes means higher wet scavenging rate of aerosols and as a result lower activity concentration of 7Be in the atmosphere, explaining the anti-correlation between the AMAD values and activity concentrations of 7Be. But this associated with possibly higher scavenging rates of aerosols does not necessarily alone explain the anti-correlation between the AMAD and the 7Be activities. The air mass origin associated with synoptic scale weather phenomena may contribute to that too. The Flextra model was used to assess the transport pattern and to explain the deviation in radionuclide activity concentrations and AMAD values observed in the site of investigation.

  15. VARIATION OF ELEMENT SPECIATION IN COAL COMBUSTION AEROSOLS WITH PARTICLE SIZE

    EPA Science Inventory

    The speciation of sulfur, iron and key trace elements (Cr, As, Se, Zn) in combustion ash aerosols has been examined as a function of size from experimental combustion units burning Utah and Illinois bituminous coals. Although predominantly present as sulfate, sulfur was also pre...

  16. Aerosol sampling: Comparison of two rotating impactors for field droplet sizing and volumetric measurements

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This paper compares the collection characteristics of a new rotating impactor for ultra fine aerosols (FLB) with the industry standard (Hock). The volume and droplet size distribution collected by the rotating impactors were measured via spectroscopy and microscopy. The rotary impactors were co-lo...

  17. Continuous aerosol size separator using inertial microfluidics and its application to airborne bacteria and viruses.

    PubMed

    Hong, Seung Chan; Kang, Joon Sang; Lee, Jung Eun; Kim, Sang Soo; Jung, Jae Hee

    2015-04-21

    A microchannel-based aerosol size separator that separates submicron aerosols according to particle inertial differences and Dean vortices in the airflow was developed for use in low-cost, portable, real-time aerosol collectors, detectors, concentrators and other such devices. The microfluidic inertial separator was furthermore applied to simultaneously separate airborne microorganisms by size, such as airborne viruses and bacteria from larger aerosols and viral particles from bacterial cells. The entire system was designed by numerical simulation and analysis. In addition, its performance was evaluated experimentally using airborne standard polystyrene latex (PSL) particles. In addition, two airborne microorganisms, Adenovirus 40 and Staphylococcus epidermidis, were used to verify the performance of the separator. The separation ratios of each bioaerosol were measured using real-time aerosol measurement instruments and quantitative polymerase chain reaction (qPCR) analysis. The system was composed of two 90° curved microchannels and three outlets for separating the virus, bacteria and larger particles. About 70% of 3 μm particles but almost none of the bioaerosols were separated out at the first outlet. In addition, more than 70% of S. epidermidis and ~70% Adenovirus were separated out at the second and third outlets, respectively. Unwanted particle loss in the system was less than 10%. The results indicated not only good separation of bioaerosols but also the potential of our separator for use in bioaerosol applications. PMID:25714231

  18. [Characteristics of Number Concentration Size Distributions of Aerosols Under Processes in Beijing].

    PubMed

    Su, Jie; Zhao, Pu-sheng; Chen, Yi-na

    2016-04-15

    The aerosol number concentration size distributions were measured by a Wide-Range Particle Spectrometer (WPS-1000XP) at an urban site of Beijing from 2012 to 2014; and the characteristics of the size distributions in different seasons and weather conditions were discussed. The results showed that the daily average number concentration of Aitken mode aerosols was highest in the spring and lowest in the autumn; the daily average number concentration of accumulation mode aerosols was bigher in the spring and winter, while lowest in summer; and the average concentration of coarse mode was highest during the winter. The Aitken mode particles had the most significant diurnal variations resulted from the traffic sources and the summer photochemical reactions. In the spring, autumn and winter, the number concentrations of accumulation mode of the nighttime was higher than that of the daytime. The coarse mode particles did not have obvious diurnal variation. During the heavy pollution process, the accumulation mode aerosols played a decisive role in PM₂.₅ concentrations and was usually removed by the north wind. The precipitation could effectively eliminate the coarse mode particles, but it bad no obvious effect on the accumulation mode particles under small speed wind and zero speed wind. During the dust process, the concentrations of coarse mode particles increased significantly, while the accumulation mode aerosol concentration was obviously decreased. PMID:27548939

  19. Factors Regulating the Size-Resolved Production and Composition of Nascent Marine Aerosols (Invited)

    NASA Astrophysics Data System (ADS)

    Keene, W. C.; Frossard, A.; Long, M. S.; Maben, J. R.; Russell, L. M.; Kieber, D. J.; Kinsey, J.; Bates, T. S.; Quinn, P.

    2010-12-01

    Bursting bubbles generated by breaking wind waves at the ocean surface are a major but poorly constrained global source for aerosol mass, volume, and number and associated reactive constituents all of which significantly influence the multiphase physicochemical evolution of Earth’s troposphere and climate. During a spring 2010 cruise of the R/V Atlantis in the eastern North Pacific Ocean, marine aerosols were produced in a high-capacity glass and Teflon generator by artificially injecting zero air into fresh flowing seawater via coarse (A) and fine (D) frits at 1.2 m depth and seawater jets impinging upon the surface. Size-resolved number concentrations and organic and inorganic composition, organic functional groups, bubble-plume volumes, and near-surface bubble sizes were characterized over ranges of bubble and seawater flow rates and headspace RH. Seawater temperature, salinity, and chlorophyll a concentrations were measured in parallel. Relative to fine frits, bubble-plume volumes generated with coarse frits were three times smaller due to the higher initial rise velocity and shorting lifetimes of larger bubbles. However, bubbles produced by both coarse and fine frits evolved in response to surface tension to similar size (0.2- to 0.5-mm diameter) near the water-air interface. Consequently, the two frit sizes produced similar number fluxes of size-resolved aerosols per unit volume air flux. Production fluxes of supermicron- and submicron-diameter size fractions varied as linear functions of air detrainment. Ranges in centroids for number size distributions of aerosols produced with coarse (70- to 100-nm dry diameter) and fine frits (60- to 80-nm dry diameter) overlapped. Centroids for size distributions produced by a bubbler-type generator deployed in open seawater adjacent to the ship ranged from 55- 60-nm dry diameter. Number-size distributions produced by water jets were shifted towards larger particles with centroids of 100- to 150-nm dry diameter

  20. SIZE-SELECTING AEROSOL CHARACTERIZATION INSTRUMENT - PHASE II

    EPA Science Inventory

    Aerodyne Research, Inc., proposes to develop a new monitor that provides composition information of particles in the ultrafine (10-100 nm), fine (100 nm-2.5 µm) and coarse (2.5-10 µm) size modes in near real time. Particle monitoring technologies are important f...

  1. Equilibrium size of atmospheric aerosol sulfates as a function of the relative humidity

    NASA Astrophysics Data System (ADS)

    Koutrakis, Petros; Wolfson, Jack M.; Spengler, John D.; Stern, Bonnie; Franklin, Claire A.

    1989-05-01

    Size-fractionated acid aerosols were collected, using a microorifice cascade impactor, during the summer of 1986 in Dunnville, Ontario, as part of the Canadian Children Acute Respiratory Effects Study (CARES), sponsored by the Department of National Health and Welfare, Canada. Sulfate and hydrogen ions showed similar size distributions. The molar ratio of H+/SO42- varied little with particle size, but there was a considerable time-dependent variation in aerosol acid content. It was also found that there is a distinct relationship between the geometric mean aerodynamic diameter of sulfate, da, and ambient relative humidity (RH). Atmospheric sulfate particle sizes observed in this study were slightly higher than those found in laboratory experiments at corresponding humidities. However, considering the uncertainties involved, the agreement between the field and laboratory data was remarkable.

  2. Ratio of aerosol and gases of radioactive chlorine and particle size distribution of aerosol formed by high-energy proton irradiation.

    PubMed

    Yokoyama, S; Sato, K; Manabe, K; Noguchi, H; Kaneko, H; Oki, Y; Iida, T; Tanaka, Su

    2007-01-01

    To estimate internal doses due to the inhalation of radionuclides produced by the nuclear spallation of the air nuclei in high-energy proton accelerator facilities, the physicochemical properties of radionuclides are very important. Thus, the ratio of aerosol and gases of 38Cl and 39Cl formed by irradiating argon gas-added air with a 48 MeV proton beam has been measured. Radionuclides of 38Cl and 39Cl exist as aerosol, acid gas and non-acid gas. The percentages of activity of 38Cl and 39Cl aerosols are about 80%. The number size distributions of non-radioactive aerosol were characterised by two peaks with diameters of 10-20 nm and larger than 20 nm. As a result predicted by a simple surface model, it was found that the activity size distribution of 38Cl aerosols can be regarded as that having a single peak at 120 nm. PMID:18033760

  3. [Size distributions of aerosol particles and the impact on visibility in winter of Nanjing].

    PubMed

    Shang, Qian; Li, Zi-Hua; Yang, Jun; Pu, Mei-Juan

    2011-09-01

    High resolution instruments were used to investigate the relationship between aerosol size distribution characteristics and meteorological factors, and its possible influence on visibility in urban Nanjing from November to December 2009. Results show that the size distribution of aerosol number concentration showed a bimodal shape with the main peak value concentrating at particle sizes of 0.04-0.1 microm. Mass concentration distribution presented a bimodal shape with the two peak values concentrating at particle sizes of 0.5-0.7 microm and 2.7 microm, and the surface area concentration distribution presented two peaks from 0.1 to 0.5 microm and from 0.5 to 0.9 microm. It is found that the diurnal and interdiurnal variations of particle concentrations are obvious. Human activities and variation of atmospheric stability had great effect on daily variation of particle concentrations, while meteorological conditions such as precipitation, wind, relative humidity and so on had strong influence on interdiurnal variation. The aerosol size distribution was significantly affected by relative humidity. When RH was lower than 54%, number concentration of aerosol particles less than 1 microm in diameter increased gradually as RH increased, and concentration of particles with diameter larger than 1 microm almost had no change. When RH was higher than 54%, number concentration of aerosol particles ranging from 0.01 to 0.2 microm and from 2.7 to 10 microm decreased with the increase of RH, in contrast, concentration of aerosol particles between 0.5 and 1.5 microm in diameter increased. In addition, the particle number size distributions were different in rainy, foggy, sunny and haze weather conditions. Compared to sunny day, concentration of particles with different sizes all decreased in rainy day. In foggy weather, The number concentration of aerosol particles ranging from 0.01 to 0.3 microm and from 2.7 to 10 microm decreased, and aerosol particles between 0.3 and 2.7 microm

  4. AEROSOL SIZE MEASUREMENT BY ELECTRICAL MOBILITY AND DIFFUSION ANALYSIS - A COMPARISON OF METHODS

    EPA Science Inventory

    The principle of the electrical aerosol analyzer method is reviewed and the diffusion battery method is described in detail. An appendix explains the basis of the calculations used. The diffusion battery method is complicated by counting losses of very small particles, inherent t...

  5. Particle Morphology and Size Results from the Smoke Aerosol Measurement Experiment-2

    NASA Technical Reports Server (NTRS)

    Urban, David L.; Ruff, Gary A.; Greenberg, Paul S.; Fischer, David; Meyer, Marit; Mulholland, George; Yuan, Zeng-Guang; Bryg, Victoria; Cleary, Thomas; Yang, Jiann

    2012-01-01

    Results are presented from the Reflight of the Smoke Aerosol Measurement Experiment (SAME-2) which was conducted during Expedition 24 (July-September 2010). The reflight experiment built upon the results of the original flight during Expedition 15 by adding diagnostic measurements and expanding the test matrix. Five different materials representative of those found in spacecraft (Teflon, Kapton, cotton, silicone rubber and Pyrell) were heated to temperatures below the ignition point with conditions controlled to provide repeatable sample surface temperatures and air flow. The air flow past the sample during the heating period ranged from quiescent to 8 cm/s. The smoke was initially collected in an aging chamber to simulate the transport time from the smoke source to the detector. This effective transport time was varied by holding the smoke in the aging chamber for times ranging from 11 to 1800 s. Smoke particle samples were collected on Transmission Electron Microscope (TEM) grids for post-flight analysis. The TEM grids were analyzed to observe the particle morphology and size parameters. The diagnostics included a prototype two-moment smoke detector and three different measures of moments of the particle size distribution. These moment diagnostics were used to determine the particle number concentration (zeroth moment), the diameter concentration (first moment), and the mass concentration (third moment). These statistics were combined to determine the diameter of average mass and the count mean diameter and, by assuming a log-normal distribution, the geometric mean diameter and the geometric standard deviations can also be calculated. Overall the majority of the average smoke particle sizes were found to be in the 200 nm to 400 nm range with the quiescent cases producing some cases with substantially larger particles.

  6. Size distribution dynamics reveal particle-phase chemistry in organic aerosol formation.

    PubMed

    Shiraiwa, Manabu; Yee, Lindsay D; Schilling, Katherine A; Loza, Christine L; Craven, Jill S; Zuend, Andreas; Ziemann, Paul J; Seinfeld, John H

    2013-07-16

    Organic aerosols are ubiquitous in the atmosphere and play a central role in climate, air quality, and public health. The aerosol size distribution is key in determining its optical properties and cloud condensation nucleus activity. The dominant portion of organic aerosol is formed through gas-phase oxidation of volatile organic compounds, so-called secondary organic aerosols (SOAs). Typical experimental measurements of SOA formation include total SOA mass and atomic oxygen-to-carbon ratio. These measurements, alone, are generally insufficient to reveal the extent to which condensed-phase reactions occur in conjunction with the multigeneration gas-phase photooxidation. Combining laboratory chamber experiments and kinetic gas-particle modeling for the dodecane SOA system, here we show that the presence of particle-phase chemistry is reflected in the evolution of the SOA size distribution as well as its mass concentration. Particle-phase reactions are predicted to occur mainly at the particle surface, and the reaction products contribute more than half of the SOA mass. Chamber photooxidation with a midexperiment aldehyde injection confirms that heterogeneous reaction of aldehydes with organic hydroperoxides forming peroxyhemiacetals can lead to a large increase in SOA mass. Although experiments need to be conducted with other SOA precursor hydrocarbons, current results demonstrate coupling between particle-phase chemistry and size distribution dynamics in the formation of SOAs, thereby opening up an avenue for analysis of the SOA formation process. PMID:23818634

  7. Ion balances of size-resolved tropospheric aerosol samples: implications for the acidity and atmospheric processing of aerosols

    NASA Astrophysics Data System (ADS)

    Kerminen, Veli-Matti; Hillamo, Risto; Teinilä, Kimmo; Pakkanen, Tuomo; Allegrini, Ivo; Sparapani, Roberto

    A large set of size-resolved aerosol samples was inspected with regard to their ion balance to shed light on how the aerosol acidity changes with particle size in the lower troposphere and what implications this might have for the atmospheric processing of aerosols. Quite different behaviour between the remote and more polluted environments could be observed. At the remote sites, practically the whole accumulation mode had cation-to-anion ratios clearly below unity, indicating that these particles were quite acidic. The supermicron size range was considerably less acidic and may in some cases have been close to neutral or even alkaline. An interesting feature common to the remote sites was a clear jump in the cation-to-anion ratio when going from the accumulation to the Aitken mode. The most likely reason for this was cloud processing which, via in-cloud sulphate production, makes the smallest accumulation-mode particles more acidic than the non-activated Aitken-mode particles. A direct consequence of the less acidic nature of the Aitken mode is that it can take up semi-volatile, water-soluble gases much easier than the accumulation mode. This feature may have significant implications for atmospheric cloud condensation nuclei production in remote environments. In rural and urban locations, the cation-to-anion ratio was close to unity over most of the accumulation mode, but increased significantly when going to either larger or smaller particle sizes. The high cation-to-anion ratios in the supermicron size range were ascribed to carbonate associated with mineral dust. The ubiquitous presence of carbonate in these particles indicates that they were neutral or alkaline, making them good sites for heterogeneous reactions involving acidic trace gases. The high cation-to-anion ratios in the Aitken mode suggest that these particles contained some water-soluble anions not detected by our chemical analysis. This is worth keeping in mind when investigating the hygroscopic

  8. Global Measurement of Junge Layer Stratospheric Aerosol with OMPS/LP. Scattering Properties and Particle Size

    NASA Astrophysics Data System (ADS)

    Rault, D. F.; Bhartia, P. K.

    2014-12-01

    The OMPS/LP was launched on board the NPP space platform in October 2011. Over the past two years, the OMPS/LP was used to retrieve the global distribution of ozone and aerosol. The paper will describe the aerosol product, which NASA is presently preparing for public release. The current OMPS/LP aerosol product consists of latitude-altitude curtains along the NPP Sun-synchronous orbit, from cloud top to about 40 km. These curtains extend from local sunrise in Southern polar region to local sunset in Northern polar region. Aerosol extinctions are produced at five distinct wavelengths, namely 513, 525, 670, 750 and 870 nm, with a sampling of 1 km in vertical direction and 1 degree latitude in the along-track direction. The OMPS/LP aerosol dataset is fairly large, with 7000 vertical profiles produced each day for each wavelength. The aerosol product will be presented in terms of extinction monthly median values and mean Angstrom coefficient (particle size). Over the past two years, the Junge layer was affected by several events such as volcanic eruptions (Nabro and Kelut) and a meteor (Chelyabinsk), the effects of which are clearly visible in the OMPS/LP dataset. The Asian Tropopause Aerosol Layer (ATAL) can also be observed in the OMPS/LP dataset. Moreover the effect of the Brewer Dobson Circulation (BDC) can be observed at high altitudes: the BDC velocity at 35 km can be estimated from the time variation of iso-density heights and was found to compare well with BDC velocities evaluated with the water vapor tape recorder technique as well as MERRA model values. Finally, aerosol filaments are clearly visible in OMPS/LP aerosol dataset as they appear as distinct "bubbles" on the OMPS/LP curtain files at periodic intervals in both the Southern and Northern hemispheres. These filaments are a main source of transport from tropical to polar region, and OMPS/LP data can therefore be instrumental in quantifying the rate of this transport. The quality of the OMPS/LP aerosol

  9. A Stokes' velocity photographic method for measuring the size distribution of aerosols

    NASA Technical Reports Server (NTRS)

    Deepak, A.

    1974-01-01

    Aerosol particles are allowed to settle in a vertical glass walled vessel, and their settling velocity is determined by photographing them while the light entering the camera is being chopped at a known rate. The settling velocity of each particle can be determined from the photographs, and by applying the Stokes' law, one can calculate the radius of each particle. The Stokes' law for a sphere settling freely in a quiet medium is given. If the volume of the photographed region of the illumination is known, the aerosol number density and size distribution can be obtained. Experiments with alumina particles of given size distributions indicate that the method works accurately. One set of a typical experiment with 3.0-micrometer Al2O3 particles is presented, which shows that the measured size distribution peaks at approximately 3.0 micrometer.

  10. Simulating SAL formation and aerosol size distribution during SAMUM-I

    NASA Astrophysics Data System (ADS)

    Khan, Basit; Stenchikov, Georgiy; Weinzierl, Bernadett; Kalenderski, Stoitchko; Osipov, Sergey

    2015-04-01

    To understand the formation mechanisms of Saharan Air Layer (SAL), we combine model simulations and dust observations collected during the first stage of the Saharan Mineral Dust Experiment (SAMUM-I), which sampled dust events that extended from Morocco to Portugal, and investigated the spatial distribution and the microphysical, optical, chemical, and radiative properties of Saharan mineral dust. We employed the Weather Research Forecast model coupled with the Chemistry/Aerosol module (WRF-Chem) to reproduce the meteorological environment and spatial and size distributions of dust. The experimental domain covers northwest Africa including the southern Sahara, Morocco and part of the Atlantic Ocean with 5 km horizontal grid spacing and 51 vertical layers. The experiments were run from 20 May to 9 June 2006, covering the period of most intensive dust outbreaks. Comparisons of model results with available airborne and ground-based observations show that WRF-Chem reproduces observed meteorological fields as well as aerosol spatial distribution across the entire region and along the airplane's tracks. We evaluated several aerosol uplift processes and found that orographic lifting, aerosol transport through the land/sea interface with steep gradients of meteorological characteristics, and interaction of sea breezes with the continental outflow are key mechanisms that form a surface-detached aerosol plume over the ocean. Comparisons of simulated dust size distributions with airplane and ground-based observations are generally good, but suggest that more detailed treatment of microphysics in the model is required to capture the full-scale effect of large aerosol particles.

  11. Measuring the stratospheric aerosol size distribution profile following the next big volcanic eruption. What is required?

    NASA Astrophysics Data System (ADS)

    Deshler, T.

    2015-12-01

    Two of the key missing features of fresh and evolving volcanic plumes are the particle size distribution and its partitioning into non-volatile ash and volatile sulfate particles. Such information would allow more refined estimates of the evolution and dispersal of the aerosol, of the impacts of the aerosol on radiation and on stratospheric chemistry, and of the overall amount of sulfur injected into the stratosphere. To provide this information aerosol measurements must be sensitive to particles in the 0.1 - 10 μm radius range, with concentration detection thresholds > 0.001 cm-3, and to the total aerosol population. An added bonus would be a size resolved measurement of the non-volatile fraction of the aerosol. The measurements must span the lower and mid stratosphere up to about 30 km. There are no remote measurements which can provide this information. In situ measurements using aerosol and condensation nuclei counters are required. Aircraft platforms are available for measurements up to 20 km, but beyond that requires balloon platforms. Measurements above 20 km would be required for a large volcanic eruption. There are balloon-borne instruments capable of fulfilling all of the measurement requirements; however such instruments are reasonably large and not expendable. The difficulty is deploying the instruments, obtaining the flight permissions from air traffic control, and recovering the instruments after flight. Such difficulties are compounded in the tropics. This talk will detail some previous experience in this area and suggest ways forward to be ready for the next big eruption.

  12. Differences between the activity size distributions of the different natural radionuclide aerosols in outdoor air

    NASA Astrophysics Data System (ADS)

    Gründel, M.; Porstendörfer, J.

    The results of the activity size distribution of the short-lived ( 218Po, 214Bi/ 214Po) and long-lived ( 210Pb, 210Po) radon decay product aerosols, the thoron decay product aerosols ( 212Pb, 212Po) and 7Be of the outdoor atmosphere are presented. The results were obtained from measurements averaged over an extended period (4 weeks) and were carried out with a low-pressure On-Line Alpha Cascade Impactor (OLACI). The size distributions of the radionuclides were obtained from the same measurement run with the OLACI, so that the size classification technique and the atmospheric and weather conditions for all radionuclides were identical. This measurement technique made it possible to measure the correct differences between the size distributions of the different natural radionuclides in the environmental air. The differences between the activity size distributions of the long- and short-lived radionuclides could be explained by coagulation with aerosol particles of the atmosphere as for instance 210Pb was shown.

  13. Sensitivity of Stratospheric Geoengineering with Black Carbon to Aerosol Size and Altitude of Injection

    NASA Technical Reports Server (NTRS)

    Kravitz, Ben; Robock, Alan; Shindell, Drew T.; Miller, Mark A.

    2012-01-01

    Simulations of stratospheric geoengineering with black carbon (BC) aerosols using a general circulation model with fixed sea surface temperatures show that the climate effects strongly depend on aerosol size and altitude of injection. 1 Tg BC/a injected into the lower stratosphere would cause little surface cooling for large radii but a large amount of surface cooling for small radii and stratospheric warming of over 60 C. With the exception of small particles, increasing the altitude of injection increases surface cooling and stratospheric warming. Stratospheric warming causes global ozone loss by up to 50% in the small radius case. The Antarctic shows less ozone loss due to reduction of polar stratospheric clouds, but strong circumpolar winds would enhance the Arctic ozone hole. Using diesel fuel to produce the aerosols is likely prohibitively expensive and infeasible. Although studying an absorbing aerosol is a useful counterpart to previous studies involving sulfate aerosols, black carbon geoengineering likely carries too many risks to make it a viable option for deployment.

  14. An effective inversion algorithm for retrieving bimodal aerosol particle size distribution from spectral extinction data

    NASA Astrophysics Data System (ADS)

    He, Zhenzong; Qi, Hong; Yao, Yuchen; Ruan, Liming

    2014-12-01

    The Ant Colony Optimization algorithm based on the probability density function (PDF-ACO) is applied to estimate the bimodal aerosol particle size distribution (PSD). The direct problem is solved by the modified Anomalous Diffraction Approximation (ADA, as an approximation for optically large and soft spheres, i.e., χ≫1 and |m-1|≪1) and the Beer-Lambert law. First, a popular bimodal aerosol PSD and three other bimodal PSDs are retrieved in the dependent model by the multi-wavelength extinction technique. All the results reveal that the PDF-ACO algorithm can be used as an effective technique to investigate the bimodal PSD. Then, the Johnson's SB (J-SB) function and the modified beta (M-β) function are employed as the general distribution function to retrieve the bimodal PSDs under the independent model. Finally, the J-SB and M-β functions are applied to recover actual measurement aerosol PSDs over Beijing and Shanghai obtained from the aerosol robotic network (AERONET). The numerical simulation and experimental results demonstrate that these two general functions, especially the J-SB function, can be used as a versatile distribution function to retrieve the bimodal aerosol PSD when no priori information about the PSD is available.

  15. Raman microscopy of size-segregated aerosol particles, collected at the Sonnblick Observatory in Austria

    NASA Astrophysics Data System (ADS)

    Ofner, Johannes; Kasper-Giebl, Anneliese; Kistler, Magdalena; Matzl, Julia; Schauer, Gerhard; Hitzenberger, Regina; Lohninger, Johann; Lendl, Bernhard

    2014-05-01

    Size classified aerosol samples were collected using low pressure impactors in July 2013 at the high alpine background site Sonnnblick. The Sonnblick Observatory is located in the Austrian Alps, at the summit of Sonnblick 3100 m asl. Sampling was performed in parallel on the platform of the Observatory and after the aerosol inlet. The inlet is constructed as a whole air inlet and is operated at an overall sampling flow of 137 lpm and heated to 30 °C. Size cuts of the eight stage low pressure impactors were from 0.1 to 12.8 µm a.d.. Alumina foils were used as sample substrates for the impactor stages. In addition to the size classified aerosol sampling overall aerosol mass (Sharp Monitor 5030, Thermo Scientific) and number concentrations (TSI, CPC 3022a; TCC-3, Klotz) were determined. A Horiba LabRam 800HR Raman microscope was used for vibrational mapping of an area of about 100 µm x 100 µm of the alumina foils at a resolution of about 0.5 µm. The Raman microscope is equipped with a laser with an excitation wavelength of 532 nm and a grating with 300 gr/mm. Both optical images and the related chemical images were combined and a chemometric investigation of the combined images was done using the software package Imagelab (Epina Software Labs). Based on the well-known environment, a basic assignment of Raman signals of single particles is possible at a sufficient certainty. Main aerosol constituents e.g. like sulfates, black carbon and mineral particles could be identified. First results of the chemical imaging of size-segregated aerosol, collected at the Sonnblick Observatory, will be discussed with respect to standardized long-term measurements at the sampling station. Further, advantages and disadvantages of chemical imaging with subsequent chemometric investigation of the single images will be discussed and compared to the established methods of aerosol analysis. The chemometric analysis of the dataset is focused on mixing and variation of single compounds at

  16. Estimation of aerosol columnar size distribution and optical thickness from the angular distribution of radiance exiting the atmosphere: simulations.

    PubMed

    Wang, M; Gordon, H R

    1995-10-20

    We report the results of simulations in which an algorithm developed for estimation of aerosol optical properties from the angular distribution of radiance exiting the top of the atmosphere over the oceans [Appl. Opt. 33, 4042 (1994)] is combined with a technique for carrying out radiative transfer computations by synthesis of the radiance produced by individual components of the aerosol-size distribution [Appl. Opt. 33, 7088 (1994)], to estimate the aerosol-size distribution by retrieval of the total aerosol optical thickness and the mixing ratios for a set of candidate component aerosol-size distributions. The simulations suggest that in situations in which the true size-refractive-index distribution can actually be synthesized from a combination of the candidate components, excellent retrievals of the aerosol optical thickness and the component mixing ratios are possible. An exception is the presence of strongly absorbing aerosols. The angular distribution of radiance in a single spectral band does not appear to contain sufficient information to separate weakly from strongly absorbing aerosols. However, when two spectral bands are used in the algorithm, retrievals in the case of strongly absorbing aerosols are improved. When pseudodata were simulated with an aerosol-size distribution that differed in functional form from the candidate components, excellent retrievals were still obtained as long as the refractive indices of the actual aerosol model and the candidate components were similar. This underscores the importance of component candidates having realistic indices of refraction in the various size ranges for application of the method. The examples presented all focus on the multiangle imaging spectroradiometer; however, the results should be as valid for data obtained by the use of high-altitude airborne sensors. PMID:21060560

  17. Stable Carbon Fractionation In Size Segregated Aerosol Particles Produced By Controlled Biomass Burning

    NASA Astrophysics Data System (ADS)

    Masalaite, Agne; Garbaras, Andrius; Garbariene, Inga; Ceburnis, Darius; Martuzevicius, Dainius; Puida, Egidijus; Kvietkus, Kestutis; Remeikis, Vidmantas

    2014-05-01

    Biomass burning is the largest source of primary fine fraction carbonaceous particles and the second largest source of trace gases in the global atmosphere with a strong effect not only on the regional scale but also in areas distant from the source . Many studies have often assumed no significant carbon isotope fractionation occurring between black carbon and the original vegetation during combustion. However, other studies suggested that stable carbon isotope ratios of char or BC may not reliably reflect carbon isotopic signatures of the source vegetation. Overall, the apparently conflicting results throughout the literature regarding the observed fractionation suggest that combustion conditions may be responsible for the observed effects. The purpose of the present study was to gather more quantitative information on carbonaceous aerosols produced in controlled biomass burning, thereby having a potential impact on interpreting ambient atmospheric observations. Seven different biomass fuel types were burned under controlled conditions to determine the effect of the biomass type on the emitted particulate matter mass and stable carbon isotope composition of bulk and size segregated particles. Size segregated aerosol particles were collected using the total suspended particle (TSP) sampler and a micro-orifice uniform deposit impactor (MOUDI). The results demonstrated that particle emissions were dominated by the submicron particles in all biomass types. However, significant differences in emissions of submicron particles and their dominant sizes were found between different biomass fuels. The largest negative fractionation was obtained for the wood pellet fuel type while the largest positive isotopic fractionation was observed during the buckwheat shells combustion. The carbon isotope composition of MOUDI samples compared very well with isotope composition of TSP samples indicating consistency of the results. The measurements of the stable carbon isotope ratio in

  18. Determination of particle nucleation and growth rates from measured aerosol size distributions

    NASA Astrophysics Data System (ADS)

    Verheggen, B.; Mozurkewich, M.

    2003-04-01

    The effects of aerosols on atmospheric chemistry, health and climate are dependent on particle size and composition, and therefore on particle nucleation and growth. An analytical model has been developed to determine nucleation and growth rates from measurements of consecutive aerosol size distributions. The evolution of an aerosol population in time is described by the General Dynamic Equation (GDE). Wall loss, coagulation loss and coagulation production are determined, based on the measured aerosol size distributions. Taking their contributions into account, a non-linear regression analysis of the GDE is performed for each time interval to find the value of the growth rate, that gives best agreement between the measured and calculated change in the size distribution. Other parameters can also be verified and/or optimized by regression analysis. Knowing the growth rate as a function of time (and size) from the regression analysis, each measured cohort of particles is tracked backwards in time to their time of formation, where the radius of the critical cluster is assumed to be 0.5 nm. The number density of each cohort has decreased since their formation, due to wall losses and coagulation processes. Perturbation theory is used to approximate the contribution of within mode coagulation in decreasing the number density. Wall losses and coagulation scavenging are well characterized for each time interval. The integrated losses, from time of formation to time of measurement, are used to obtain the number of nucleated particles, and ultimately the -empirically determined- nucleation rate. The analysis is applied to measurements made in Calspan's 590 m3 smog chamber, following SO2 nucleation.

  19. Simplifying aerosol size distributions modes simultaneously detected at four monitoring sites during SAPUSS

    NASA Astrophysics Data System (ADS)

    Brines, M.; Dall'Osto, M.; Beddows, D. C. S.; Harrison, R. M.; Querol, X.

    2013-10-01

    The analysis of aerosol size distributions is a useful tool for understanding the sources and the processes influencing particle number concentrations (N) in urban areas. Hence, during the one month SAPUSS campaign (Solving Aerosol Problems by Using Synergistic Strategies, EU Marie Curie Action) in autumn 2010 in Barcelona (Spain), four SMPS (Scanning Mobility Particle Sizers) were simultaneously deployed at four monitoring sites: a road side (RSsite), an urban background site located in the city (UBsite), an urban background located in the nearby hills of the city (Torre Collserola, TCsite) and a regional background site located about fifty km from the Barcelona urban areas (RBsite). The spatial distribution of sites allows study of the aerosol temporal variability as well as the spatial distribution, progressively moving away from urban aerosol sources. In order to interpret the datasets collected, a k-means cluster analysis was performed on the combined SMPS datasets. This resulted in nine clusters describing all aerosol size distributions from the four sites. In summary there were three main categories (with three clusters in each category): "Traffic" (Traffic 1 "Tclus1" - 8%, Traffic 2 "Tclus2" - 13%, Traffic 3, "Tclus3" - 9%), "Background Pollution" (Urban Background 1 "UBclus1" - 21%, Regional Background 1, "RBclus1" - 15%, Regional Background 2, "RBclus2" - 18%) and "Special cases" (Nucleation "NUclus" - 5%, Regional Nitrate, "NITclus" - 6%, and Mix "MIXclus" - 5%). As expected, the frequency of traffic clusters (Tclus1-3) followed the order RSsite, UBsite, TCsite, and RBsite. These showed typical traffic modes mainly distributed at 20-40 nm. The urban background sites (UBsite and TCsite) reflected also as expected urban background number concentrations (average values, N = 2.4×104 cm-3 relative to 1.2×105 cm-3 seen at RSsite). The cluster describing the urban background pollution (UBclus1) could be used to monitor the sea breeze circulation towards the

  20. Aerosol size-resolved trace metal composition in remote northern tropical Atlantic marine environment: case study Cape Verde islands

    NASA Astrophysics Data System (ADS)

    Fomba, K. W.; Müller, K.; van Pinxteren, D.; Herrmann, H.

    2013-05-01

    Size-resolved trace metal concentrations of 15 elements in aerosol particles at the Cape Verde Atmospheric Observatory (CVAO) under remote background conditions were investigated through analysis of aerosol samples collected during intensive field studies from January 2007 to November 2011 using total reflection x-ray fluorescence (TXRF). The identification of the main air mass origin that influence remote marine aerosol in the northern tropical Atlantic has been investigated. In total, 317 samples were collected. The dataset was analyzed according to the main air mass inflow at the station. We found that remote conditions make up about 45% of the meteorological conditions in a year at CVAO and thus the northern tropical Atlantic. Surprisingly, air masses from North America are often responsible for higher trace metal concentrations in this region. Elements such as Zn, Pb, Cu, Cr, Ni, and V were mostly found in the submicron size fractions, while elements with dominant crustal or oceanic origin such as Fe, Ti, Mn, Sr, and Rb were found in the coarse fractions (>1 μm). The highest metal concentrations, especially for Zn (3.23 ng m-3), Cu (0.81 ng m-3), Sr (2.63 ng m-3), and Cr (0.53 ng m-3), were observed in air masses originating from North America and the concentrations were within the same concentration range to those reported previously in the literature for remote marine aerosols. Fe (12.26 ng m-3), Ti (0.91 ng m-3), and Mn (0.35 ng m-3) showed higher concentrations when air mass came from Europe and the Canary Islands. Pb concentration was low (<0.20 ng m-3) and did not vary significantly with air mass direction. The low Pb concentration is indicative of the complete phase-out of leaded gasoline even in African countries. Crustal enrichment factor values decreased from fine to coarse-mode particles with low values (<4) observed for Fe, Mn, and Rb, and high values (>20) for Zn, Cu, Ni, Cr, Pb, and Se. The observed enrichment of the elements was attributed to

  1. Aerosol size-resolved trace metal composition in remote northern tropical Atlantic marine environment: case study Cape Verde Islands

    NASA Astrophysics Data System (ADS)

    Fomba, K. W.; Müller, K.; van Pinxteren, D.; Herrmann, H.

    2012-11-01

    Size-resolved trace metal concentrations of 15 elements in aerosol particles at the Cape Verde Atmospheric Observatory (CVAO) under remote background conditions were investigated through analysis of aerosol samples collected during intensive field studies from January 2007 to November 2011 using total reflection x-ray fluorescence (TXRF). The identification of the main air mass origin that influence remote marine aerosol in the northern tropical Atlantic has been investigated. In total 317 samples were collected. The dataset was analyzed according to the main air mass inflow at the station. We found that remote conditions make up about 45% of the meteorological conditions in a year at CVAO and thus the northern tropical Atlantic. Surprisingly, air masses from North America are often responsible for higher trace metal concentrations in this region. Elements such as Zn, Pb, Cu, Cr, Ni, and V were mostly found in the submicron size fractions while elements with dominant crustal or oceanic origin such as Fe, Ti, Mn, Sr, and Rb, were found in the coarse fractions (>1 μm). The highest metal concentrations especially for Zn (3.23 ng m-3), Cu (0.81 ng m-3), Sr (2.63 ng m-3), and Cr (0.53 ng mm-3), were observed in air masses originating from North America and the concentrations were within the same concentration range to those reported previously in the literature for remote marine aerosols. Fe (12.26 ng m-3), Ti (0.91 ng m-3) and Mn (0.35 ng m-3) showed higher concentrations when air mass came from Europe and the Canary Islands. Pb concentration was low (< 0.20 ng m-3) and did not vary significantly with air mass direction. The low Pb concentration is indicative of the complete phased out of leaded gasoline even in African countries. Crustal enrichment factor values decreased from fine to coarse mode particles with low values (< 4) observed for Fe, Mn, and Rb and high values (> 20) for Zn, Cu, Ni, Cr, Pb, and Se. The observed enrichment of the elements was attributed to

  2. Aged boreal biomass-burning aerosol size distributions from BORTAS 2011

    NASA Astrophysics Data System (ADS)

    Sakamoto, K. M.; Allan, J. D.; Coe, H.; Taylor, J. W.; Duck, T. J.; Pierce, J. R.

    2015-02-01

    Biomass-burning aerosols contribute to aerosol radiative forcing on the climate system. The magnitude of this effect is partially determined by aerosol size distributions, which are functions of source fire characteristics (e.g. fuel type, MCE) and in-plume microphysical processing. The uncertainties in biomass-burning emission number-size distributions in climate model inventories lead to uncertainties in the CCN (cloud condensation nuclei) concentrations and forcing estimates derived from these models. The BORTAS-B (Quantifying the impact of BOReal forest fires on Tropospheric oxidants over the Atlantic using Aircraft and Satellite) measurement campaign was designed to sample boreal biomass-burning outflow over eastern Canada in the summer of 2011. Using these BORTAS-B data, we implement plume criteria to isolate the characteristic size distribution of aged biomass-burning emissions (aged ~ 1-2 days) from boreal wildfires in northwestern Ontario. The composite median size distribution yields a single dominant accumulation mode with Dpm = 230 nm (number-median diameter) and σ = 1.5, which are comparable to literature values of other aged plumes of a similar type. The organic aerosol enhancement ratios (ΔOA / ΔCO) along the path of Flight b622 show values of 0.09-0.17 μg m-3 ppbv-1 (parts per billion by volume) with no significant trend with distance from the source. This lack of enhancement ratio increase/decrease with distance suggests no detectable net OA (organic aerosol) production/evaporation within the aged plume over the sampling period (plume age: 1-2 days), though it does not preclude OA production/loss at earlier stages. A Lagrangian microphysical model was used to determine an estimate of the freshly emitted size distribution corresponding to the BORTAS-B aged size distributions. The model was restricted to coagulation and dilution processes based on the insignificant net OA production/evaporation derived from the ΔOA / ΔCO enhancement ratios. We

  3. Software to analyze the relationship between aerosol, clouds, and precipitation: SAMAC

    NASA Astrophysics Data System (ADS)

    Gagné, S.; MacDonald, L. P.; Leaitch, W. R.; Pierce, J. R.

    2016-02-01

    The analysis of aircraft-based measurements of clouds is critical for studies of aerosol and of clouds. Many such measurements have been taken, but it is difficult to compare such data across instruments, flights and campaigns. We present a new open-source software program, SAMAC (Software for Airborne Measurements of Aerosol and Clouds), that may enable a more systematic and comparable approach to the analysis of aerosol-cloud-precipitation data. The software offers a cooperative and reproducible approach to the analysis of aircraft measurements of clouds across campaigns. SAMAC is an object-oriented software program in which a cloud is an object; all the data related to a cloud is contained in the cloud object. The cloud objects come with built-in methods and functions that allow for the quick generation of basic plots and calculations, SAMAC provides a quick view of the data set and may be used to compare clouds and to filter for specific characteristics. Other researchers can readily use already submitted algorithms once their data is placed in the cloud structure provided, and they can contribute their own algorithms to the software for others to see and use. This approach would improve comparability, reproducibility and transparency by allowing others to replicate results and test the same algorithms on different data. SAMAC can be downloaded at https://github.com/StephGagne/SAMAC/releases.

  4. Size Distribution and Chemical Characteristic of Aerosols in Northwestern Black Sea Region of Turkey

    NASA Astrophysics Data System (ADS)

    Oztürk, Fatma; Keles, Melek; Halif Ngagine, Soulemane

    2016-04-01

    Size segregated PM samples were collected at the city center of Bolu, which is northwestern part of the Black Sea region of Turkey between 2015 and 2016. A cascade impactor was used for the collection of weekly PM samples on pre-fired quartz filters in eight different size ranges (9.0-10.0 μm, 5.8-9.0 μm, 4.7-5.8 μm, 3.3-4.7 μm, 2.1-3.3 μm, 1.1-2.1 μm, 0.65-1.1 μm, 0.43-0.65 μm). The collected samples were divided in three parts and each part was analyzed with different analytical technique. The first part of the filter was analyzed in terms of major ions (SO42-, NO3-, Cl-, NH4+, K+, Ca2+, Mg2+, Na+). A large suit of metals from Li to U were determined in the second fraction of the filter by means of ICPMS. Lastly, the third part of the filter was analyzed in terms of EC and OC. The preliminary results indicated that the PM mass depicted bimodal distribution and the average concentration of PM10 was about 100 μg/m3for a five week period. Both EC and OC showed bi-modal distribution while these two parameters were more enriched on smaller particles. The average concentrations of EC and OC in PM1 were determined as 4.1 and 40.6 μg/m3, respectively, indicating the secondary organic aerosol formation in Bolu ambient air. Among the major ions, SO42- and NH4+ depicted unimodal distribution having significantly higher concentrations in fine particles (< 1 μm) while the rest of the ions present bimodal distribution. Mass closure analysis will be applied to the generated data set and sources will be evaluated by applying PMF. This project was supported financially by Turkish Scientific and Technological Research Council (TÜBİTAK) with a project number 114Y429.

  5. Systematic Relationships Between Lidar Observables And Sizes And Mineral Composition Of Dust Aerosols

    NASA Astrophysics Data System (ADS)

    van Diedenhoven, B.; Perlwitz, J. P.; Fridlind, A. M.; Chowdhary, J.; Cairns, B.; Stangl, A. J.

    2015-12-01

    The physical and chemical properties of soil dust aerosol particles fundamentally affect their interaction with climate, including shortwave absorption and radiative forcing, nucleation of cloud droplets and ice crystals, heterogeneous formation of sulfates and nitrates on the surface of dust particles, and atmospheric processing of iron into bioavailable forms that increase the productivity of marine phytoplankton. Lidar measurements, such as extinction-to-backscatter, color and depolarization ratios, are frequently used to distinguish between aerosol types with different physical and chemical properties. The chemical composition of aerosol particles determines their complex refractive index, hence affecting their backscattering properties. Here we present a study on how dust aerosol backscattering and depolarization properties at wavelengths of 355, 532 and 1064 nm are related to size and complex refractive index, which varies with the mineral composition of the dust. Dust aerosols are represented by collections of spheroids with a range of prolate and oblate aspect ratios and their optical properties are obtained using T-matrix calculations. We find simple, systematic relationships between lidar observables and the dust size and complex refractive index that may aid the use of space-based or airborne lidars for direct retrieval of dust properties or for the evaluation of chemical transport models using forward simulated lidar variables. In addition, we present first results on the spatial variation of forward-simulated lidar variables based on a dust model that accounts for the atmospheric cycle of eight different mineral types plus internal mixtures of seven mineral types with iron oxides, which was recently implemented in the NASA GISS Earth System ModelE2.

  6. Systematic Relationships Between Lidar Observables and Sizes And Mineral Composition Of Dust Aerosols

    NASA Technical Reports Server (NTRS)

    Van Diedenhoven, Bastiaan; Stangl, Alexander; Perlwitz, Jan; Fridlind, Ann M.; Chowdhary, Jacek; Cairns, Brian

    2015-01-01

    The physical and chemical properties of soil dust aerosol particles fundamentally affect their interaction with climate, including shortwave absorption and radiative forcing, nucleation of cloud droplets and ice crystals, heterogeneous formation of sulfates and nitrates on the surface of dust particles, and atmospheric processing of iron into bioavailable forms that increase the productivity of marine phytoplankton. Lidar measurements, such as extinction-to-backscatter, color and depolarization ratios, are frequently used to distinguish between aerosol types with different physical and chemical properties. The chemical composition of aerosol particles determines their complex refractive index, hence affecting their backscattering properties. Here we present a study on how dust aerosol backscattering and depolarization properties at wavelengths of 355, 532 and 1064 nm are related to size and complex refractive index, which varies with the mineral composition of the dust. Dust aerosols are represented by collections of spheroids with a range of prolate and oblate aspect ratios and their optical properties are obtained using T-matrix calculations. We find simple, systematic relationships between lidar observables and the dust size and complex refractive index that may aid the use of space-based or airborne lidars for direct retrieval of dust properties or for the evaluation of chemical transport models using forward simulated lidar variables. In addition, we present first results on the spatial variation of forward-simulated lidar variables based on a dust model that accounts for the atmospheric cycle of eight different mineral types plus internal mixtures of seven mineral types with iron oxides, which was recently implemented in the NASA GISS Earth System ModelE2.

  7. MASS AND COMPOSITION OF AN URBAN AEROSOL AS A FUNCTION OF PARTICLE SIZE FOR SEVERAL VISIBILITY LEVELS

    EPA Science Inventory

    An atmospheric aerosol sampling analysis experiment at a site near the center of the New York metropolitan area was carried out to delineate relationships existing between degree of visibility and various aerosol characteristics in a polluted atmosphere. Size-fractionated and unf...

  8. Effect of particle size of bronchodilator aerosols on lung distribution and pulmonary function in patients with chronic asthma.

    PubMed

    Mitchell, D M; Solomon, M A; Tolfree, S E; Short, M; Spiro, S G

    1987-06-01

    The particle size of bronchodilator aerosols may be important in determining the site of deposition in the lung and their therapeutic effect. The distribution of aerosols (labelled with technetium-99m diethylene triamine pentacetic acid) of two different particle sizes has been studied by gamma camera imaging. The particles had mass median aerodynamic diameters (geometric standard deviations) of 1.4 (1.4) and 5.5 (2.3) micron, and they were administered from a jet nebuliser to eight patients with chronic severe stable asthma. There was no significant difference in peripheral lung deposition with the two aerosols in any patient. The bronchodilator effect of the two aerosols was determined from cumulative dose-response studies. To avoid large doses that might mask possible differences in effect due to aerosol size, small, precisely determined incremental amounts of salbutamol (25-250 micrograms total lung dose) were used. The two doses were given via a nebuliser on separate occasions and the bronchodilator response was measured from FEV1, forced vital capacity, and peak expiratory flow 30 minutes after each dose. Bronchodilatation was similar with the two aerosols at each dose of salbutamol. There was therefore no difference in distribution within the lung or any difference in bronchodilator effect between an aerosol of small (1.4 micron) particle size and an aerosol of 5.5 microns in patients with severe but stable asthma. PMID:3660305

  9. An Investigation of Aerosol Measurements from the Halogen Occultation Experiment: Validation, Size Distributions, Composition, and Relation to Other Chemical Species

    NASA Technical Reports Server (NTRS)

    Deshler, Terry; Hervig, Mark E.

    1998-01-01

    The efforts envisioned within the original proposal (accepted February 1994) and the extension of this proposal (accepted February 1997) included measurement validations, the retrieval of aerosol size distributions and distribution moments, aerosol correction studies, and investigations of polar stratospheric clouds. A majority of the results from this grant have been published. The principal results from this grant are discussed.

  10. Martian dust aerosols and clouds in the North Polar summer: size and sedimentation

    NASA Astrophysics Data System (ADS)

    Lemmon, M. T.; Mason, E.

    2013-12-01

    Martian dust aerosols control an important part of the energy transport in the Martian atmosphere. Ice aerosols, especially in the North Polar summer, play an important role in energy transport, scavenge the atmosphere of dust, and play a role in the vertical and horizontal transport of water away from the sublimating polar cap. Their physical properties, such as size and shape, have not been directly measured, and are only measureable through remote sensing. We report two novel measurements of dust and ice aerosol physical properties with data from the Phoenix Lander's Surface Stereo Imager. First, the scoop on the Phoenix Robotic Arm was used as an occultation instrument, blocking the Sun and allowing images of the near-Sun sky without contamination from the much-brighter direct sunlight. This allows the use of diffraction scattering to measure the dust size distribution. The general technique has been used frequently, but the shading of the Sun allows much more precise and accurate probing, especially of the larger end of the size distribution. Second, direct solar images on many occasions show scattered sky light significantly above the instrument background during cloudy times. These measurements, corrected for the dust background, show light diffracted by cloud particles. Statistics of the magnitude and width of the diffraction peak demonstrate the common presence of 30-micron scale ice crystals above the Phoenix site, consistent with estimates made from the observation of fall streaks by the Lidar.

  11. Martian dust aerosols and clouds in the North Polar summer: size and sedimentation

    NASA Astrophysics Data System (ADS)

    Lemmon, Mark T.; Mason, E.

    2013-10-01

    Martian dust aerosols control an important part of the energy transport in the Martian atmosphere. Ice aerosols, especially in the North Polar summer, play an important role in energy transport, scavenge the atmosphere of dust, and play a role in the vertical and horizontal transport of water away from the sublimating polar cap. Their physical properties, such as size and shape, have not been directly measured, and are only measureable through remote sensing. We report two novel measurements of dust and ice aerosol physical properties with data from the Phoenix Lander’s Surface Stereo Imager. First, the scoop on the Phoenix Robotic Arm was used as an occultation instrument, blocking the Sun and allowing images of the near-Sun sky without contamination from the much-brighter direct sunlight. This allows the use of diffraction scattering to measure the dust size distribution. The general technique has been used frequently, but the shading of the Sun allows much more precise and accurate probing, especially of the larger end of the size distribution. Second, direct solar images on many occasions show scattered sky light significantly above the instrument background during cloudy times. These measurements, corrected for the dust background, show light diffracted by cloud particles. Statistics of the magnitude and width of the diffraction peak demonstrate the common presence of 30-micron scale ice crystals above the Phoenix site, consistent with estimates made from the observation of fall streaks by the Lidar.

  12. Aerodynamic size associations of 212Pb and 214Pb in ambient aerosols.

    PubMed

    Papastefanou, C; Bondietti, E A

    1987-11-01

    The aerodynamic size distributions of short-lived Rn daughters (reported as 214Pb and 212Pb) in ambient aerosol particles were measured using low-pressure as well as conventional low-volume and high-volume impactors. The activity distribution of 214Pb and 212Pb, measured by alpha spectroscopy, was largely associated with submicron aerosols in the accumulation mode (0.08 to 2 microns). The activity median aerodynamic diameter ranged from 0.09 to 0.37 micron (mean 0.16 micron) for 214Pb and from 0.07 to 0.25 micron (mean 0.13 micron) for 212Pb. The mean values of the geometric standard deviation (sigma g) were 2.97 and 2.86, respectively. By comparison, the median diameters of cosmogenic 7Be and ambient SO4(2-) were about 0.24 micron higher. In almost 70% of the low-pressure impactor measurements, the activity distribution of 214Pb showed a small shift to larger particle sizes relative to 212Pb. This shift probably results from alpha-recoil detachment of parent 218Po, which preferentially depletes 214Pb from smaller particles. The subsequent recondensation of 214Pb causes an enrichment of larger aerosols. Early morning and afternoon measurements indicated that similar size associations of 214Pb occur, despite humidity differences and the potential for fresh particle production in the afternoon. Health physics implications of the results are also discussed. PMID:3667271

  13. In situ measurement of the aerosol size distribution in stratospheric solid rocket motor exhaust plumes

    NASA Astrophysics Data System (ADS)

    Ross, M. N.; Whitefield, P. D.; Hagen, D. E.; Hopkins, A. R.

    The concentration and size distribution of aerosol in the stratospheric exhaust plumes of two Space Shuttle rockets and one Titan IV rocket were measured using a two component aerosol sampling system carried aboard a WB-57F aircraft. Aerosol size distribution in the 0.01 µm to 4 µm diameter size range was measured using a two component sampling system. The measured distributions display a trimodal form with modes near 0.005 µm, 0.09 µm, and 2.03 µm and are used to infer the relative mass fractionation among the three modes. While the smallest mode has been estimated to contain as much as 10% of the total mass of SRM exhaust alumina, we find show that the smallest mode contains less than 0.05% of the alumina mass. This fraction is so small so as to significantly reduce the likelihood that heterogeneous reactions on the SRM alumina surfaces could produce a significant global impact on stratospheric chemistry.

  14. Vertical Profiles of Aerosol Particle Sizes using MGS/TES and MRO/MCS

    NASA Astrophysics Data System (ADS)

    Wolff, M. J.; Clancy, R. T.; Smith, M. D.; Benson, J. L.; McConnochie, T. H.; Pankine, A.

    2012-12-01

    Vertical variations in aerosol particle sizes often have a dramatic impact on the state and evolution of the Martian atmosphere. Recent analyses of data from the Spectroscopy for the Investigation of the Characteristics of the Atmosphere of Mars (SPICAM), the Thermal Emission Spectrometer (TES), and the Mars Climate Sounder (MCS) instruments offer some long overdue progress in constraining this aspect of aerosols. However, significantly more work remains to be done along these lines in order to better constrain and inform modern dynamical simulations of the Martian atmosphere. Thus, the primary goal of our work is to perform retrievals of particle size as a function of altitude for both dust and water ice aerosols. The choice of the TES and MCS dataset, with pole-to-pole coverage over a period of nearly eight martian years, provides the crucial systematic temporal and spatial sampling. Our presentation will include: 1) A summary of our limb radiative transfer algorithms and retrieval schemes; 2) The initial results of the application of our particle size retrieval scheme to the 2001 TES and 2007 MCS observations of those planet encircling dust events; 3) Near-term plans for for additional retrievals (aphelion cloud season, lower optical depth locations and seasons, etc.); 4) Location of the archive to be used for the distribution of the derived profiles and associated retrieval metadata.

  15. Single-Species Aerosol Coagulation and Deposition with Arbitrary Size Resolution.

    SciTech Connect

    SAJO, ERNO

    2012-07-31

    Version 00 SAEROSA solves the dynamic aerosol coagulation and deposition problem with arbitrary computational precision under a variety of conditions. The code includes numerous user-selectable coagulation kernels, alone or in combinations, and permits an arbitrary initial size distribution. Many parameter combinations and what-if scenarios under user control are possible. The output gives the particle size distribution suspended in the carrier fluid initially and after the desired aerosol aging time in terms of both differential and integral aerosol volume concentrations. An auxiliary routine designed for the Mac OSX environment provides plotting capability. The output can be further processed by e.g., spreadsheets. The code has been benchmarked against three computer models, including MAEROS, and analytical models with excellent agreement. The test cases also included scenarios where previously published computational coagulation models lack capabilities or exhibit numerical instabilities. These included narrow, delta function, and non-lognormal initial size distributions, and further conditions, such as the presence of simultaneous coagulation mechanisms, including electrostatic effects, spanning multiple flow-regimes.

  16. Single-Species Aerosol Coagulation and Deposition with Arbitrary Size Resolution.

    2012-07-31

    Version 00 SAEROSA solves the dynamic aerosol coagulation and deposition problem with arbitrary computational precision under a variety of conditions. The code includes numerous user-selectable coagulation kernels, alone or in combinations, and permits an arbitrary initial size distribution. Many parameter combinations and what-if scenarios under user control are possible. The output gives the particle size distribution suspended in the carrier fluid initially and after the desired aerosol aging time in terms of both differential andmore » integral aerosol volume concentrations. An auxiliary routine designed for the Mac OSX environment provides plotting capability. The output can be further processed by e.g., spreadsheets. The code has been benchmarked against three computer models, including MAEROS, and analytical models with excellent agreement. The test cases also included scenarios where previously published computational coagulation models lack capabilities or exhibit numerical instabilities. These included narrow, delta function, and non-lognormal initial size distributions, and further conditions, such as the presence of simultaneous coagulation mechanisms, including electrostatic effects, spanning multiple flow-regimes.« less

  17. Modal structure of chemical mass size distribution in the high Arctic aerosol

    NASA Astrophysics Data System (ADS)

    Hillamo, Risto; Kerminen, Veli-Matti; Aurela, Minna; MäKelä, Timo; Maenhaut, Willy; Leek, Caroline

    2001-11-01

    Chemical mass size distributions of aerosol particles were measured in the remote marine boundary layer over the central Arctic Ocean as part of the Atmospheric Research Program on the Arctic Ocean Expedition 1996 (AOE-96). An inertial impaction method was used to classify aerosol particles into different size classes for subsequent chemical analysis. The particle chemical composition was determined by ion chromatography and by the particle-induced X-ray emission technique. Continuous particle size spectra were extracted from the raw data using a data inversion method. Clear and varying modal structures for aerosols consisting of primary sea-salt particles or of secondary particles related to dimethyl sulfide emissions were found. Concentration levels of all modes decreased rapidly when the distance from open sea increased. In the submicrometer size range the major ions found by ion chromatography were sulfate, methane sulfonate, and ammonium. They had most of the time a clear Aitken mode and one or two accumulation modes, with aerodynamic mass median diameters around 0.1 μm, 0.3 μm, and between 0.5-1.0 μm, respectively. The overall submicron size distributions of these three ions were quite similar, suggesting that they were internally mixed over most of this size range. The corresponding modal structure was consistent with the mass size distributions derived from the particle number size distributions measured with a differential mobility particle sizer. The Aitken to accumulation mode mass ratio for nss-sulfate and MSA was substantially higher during clear skies than during cloudy periods. Primary sea-salt particles formed a mode with an aerodynamic mass median diameter around 2 μm. In general, the resulting continuous mass size distributions displayed a clear modal structure consistent with our understanding of the two known major source mechanisms. One is the sea-salt aerosol emerging from seawater by bubble bursting. The other is related to

  18. Atmospheric aerosols size distribution properties in winter and pre-monsoon over western Indian Thar Desert location

    NASA Astrophysics Data System (ADS)

    Panwar, Chhagan; Vyas, B. M.

    2016-05-01

    The first ever experimental results over Indian Thar Desert region concerning to height integrated aerosols size distribution function in particles size ranging between 0.09 to 2 µm such as, aerosols columnar size distribution (CSD), effective radius (Reff), integrated content of total aerosols (Nt), columnar content of accumulation and coarse size aerosols particles concentration (Na) (size < 0.5 µm) and (Nc) (size between 0.5 to 2 µm) have been described specifically during winter (a stable weather condition and intense anthropogenic pollution activity period) and pre-monsoon (intense dust storms of natural mineral aerosols as well as unstable atmospheric weather condition period) at Jaisalmer (26.90°N, 69.90°E, 220 m above surface level (asl)) located in central Thar desert vicinity of western Indian site. The CSD and various derived other aerosols size parameters are retrieved from their average spectral characteristics of Aerosol Optical Thickness (AOT) from UV to Infrared wavelength spectrum measured from Multi-Wavelength solar Radiometer (MWR). The natures of CSD are, in general, bio-modal character, instead of uniformly distributed character and power law distributions. The observed primary peaks in CSD plots are seen around about 1013 m2 μm-1 at radius range 0.09-0.20 µm during both the seasons. But, in winter months, secondary peaks of relatively lower CSD values of 1010 to 1011 m2/μm-1 occur within a lower radius size range 0.4 to 0.6 µm. In contrast to this, while in dust dominated and hot season, the dominated secondary maxima of the higher CSD of about 1012 m2μm-3 is found of bigger aerosols size particles in a rage of 0.6 to 1.0 µm which is clearly demonstrating the characteristics of higher aerosols laden of bigger size aerosols in summer months relative to their prevailed lower aerosols loading of smaller size aerosols particles (0.4 to 0.6 µm) in cold months. Several other interesting features of changing nature of monthly spectral AOT

  19. Relationship Between Aerosol Number Size Distribution and Atmospheric Electric Potential Gradient in an Urban Area

    NASA Astrophysics Data System (ADS)

    Wright, Matthew; Matthews, James; Bacak, Asan; Silva, Hugo; Priestley, Michael; Percival, Carl; Shallcross, Dudley

    2016-04-01

    Small ions are created in the atmosphere by ground based radioactive decay and solar and cosmic radiation ionising the air. The ionosphere is maintained at a high potential relative to the Earth due to global thunderstorm activity, a current from the ionosphere transfers charge back to the ground through the weakly ionised atmosphere. A potential gradient (PG) exists between the ionosphere and the ground that can be measured in fair weather using devices such as an electric field mill. PG is inversely-proportional to the conductivity of the air and therefore to the number of ions of a given electrical mobility; a reduction of air ions will cause an increase of PG. Aerosols in the atmosphere act as a sink of air ions with an attachment rate dependent on aerosol size distribution and ion mobility. These relationships have been used to infer high particulate, and hence pollution, levels in historic datasets of atmospheric PG. A measurement campaign was undertaken in Manchester, UK for three weeks in July and August where atmospheric PG was measured with an electric field mill (JCI131, JCI Chilworth) on a second floor balcony, aerosol size distribution measured with a scanning mobility particle sizer (SMPS, TSI3936), aerosol concentration measured with a condensation particle counter (CPC, Grimm 5.403) and local meteorological measurements taken on a rooftop measurement site ~200 m away. Field mill and CPC data were taken at 1 s intervals and SMPS data in 2.5 minute cycles. Data were excluded for one hour either side of rainfall as rainclouds and droplets can carry significant charge which would affect PG. A quantity relating to the attachment of ions to aerosol (Ion Sink) was derived from the effective attachment coefficient of the aerosols. Further measurements with the field mill and CPC were taken at the same location in November 2015 when bonfire events would be expected to increase aerosol concentrations. During the summer measurements, particle number count (PNC

  20. Laboratory application of laser grain-size analyzer in determining suspended sediment concentration

    NASA Astrophysics Data System (ADS)

    Liu, Xiao; Feng, Xiuli; Liu, Jie; Lin, Lin

    2014-06-01

    Suspended sediment concentration (SSC) is an important parameter in marine sedimentology. With the development of technology, many acoustic and optical devices, such as the Laser In-Situ Scattering and Transmissometry, have been designed to measure in situ SSC and grain size distribution. But due to fund or other restrictions, many experiments were only conducted in laboratory, using an indoor laser grain-size analyzer and gravimetric method to measure grain size distribution and concentration, respectively. In this study the laboratory experiment is simplified by omitting the tiring step of gravimetric method. The connections between SSC and other parameters (obscuration, D50 and sorting index) were investigated based on 124 surface sediment samples collected from different offshore areas. A new method is developed for determining SSC in laboratory using a laser grain-size analyzer.

  1. Non-supervised Classification of Ground-based Radiometer Retrievals in Order to Assess the Natural Distribution of Aerosol Volume Size Distributions and Refractive Indexes

    NASA Astrophysics Data System (ADS)

    Gross, L.; Frouin, R.; Pietras, C.; Knobelspiesse, K.; Fargion, G.

    2002-05-01

    Ocean color algorithms generally use aerosol mixture models to firstly evaluate the atmospheric contribution to the signal (atmospheric correction) and secondly derive the oceanic content, indexed by chlorophyll a concentration. Indeed the accuracy of ocean color retrievals from SeaWiFS, POLDER, OCTS, MODIS, GLI, MERIS, etc., relies on assumptions of the optical properties associated with each aerosol type. Gordon and Wang (1994) used nine reference aerosol models, namely the Shettle and Fenn 1979) maritime and tropospheric models with a humidity variation of the aerosol optical properties and a coastal aerosol model, actually a mixture of the maritime and tropospheric models. These models may or may not be realistic. Shettle and Fenn (1979) developed their models using aerosol samples for which they derived the optical characteristics. In atmospheric correction, however, we are more interested in the optical behavior of the aerosols through the entire atmosphere. Comparisons of SeaWiFS-derived and measured aerosol optical thickness (Ainsworth et al., 2001), on the other hand, have revealed a systematic underestimation of the Angstrom coefficient. This might be evidence that the reference models are not representative of actual conditions, although it is not excluded that the discrepancy might be due to the procedure to select the models or to errors in the radiometric calibration. To provide answers to the above questions (i.e., representation of the models, origin of atmospheric correction errors), and ultimately improve atmospheric correction, one needs to analyze atmospheric optics data under varied aerosol conditions, i.e., encountered over the world oceans. Since 1997 the SIMBIOS Project has augmented the AERONET network with 12 additional island and coastal sites, including the Hawaiian Islands (Lanai and Oahu), Ascension Island, Bahrain, Tahiti, Wallops Island (US East Coast), South Korea, Turkey, Argentina, Azores, and Australia and more recently Morocco

  2. ACE-Asia: Size Resolved Sampling of Aerosols on the Ronald H Brown and US Western Receptor Sites

    NASA Astrophysics Data System (ADS)

    Jimenez-Cruz, M. P.; Cliff, S. S.; Perry, K. D.; Cahill, T. A.; Bates, T. S.

    2001-12-01

    The ACE (Aerosol Characterization Experiment)-Asia project was pre-dominantly performed during the spring of 2001. In addition to the core Asian sampling sites, we sampled at 4 Western US receptor sites. The receptor sites include, Mauna Loa Observatory, Hawaii, Crater Lake Oregon, Adak Island, Alaska and Rattlesnake Mountain, Washington. A small subset of sites (Rattlesnake Mtn., MLO, and Asian sites) continued during a 6-week intensive summer study. For the spring study, an 8-stage DRUM impactor also sampled aboard the NOAA ship RV Ronald H Brown, and mix of 8- and 3-DRUM impactors were used at the western US receptor sites. The impactors are capable of size-segregated, time-resolved aerosol collection. The size categories for the 8-DRUM are inlet-5.00, 5.00-2.50, 2.50-1.15, 1.15-0.75, 0.75-0.56, 0.56-0.34, 0.34-.026, 0.26-.09 microns and 3-DRUM: 2.50-1.10, 1.10-0.34, 0.34-0.12 microns. These samples were analyzed in 6 hour time bites using synchrotron-XRF for quantitative composition for elements sodium through uranium, when present. A major dust event occurring around April 13 was detected at all receptor sites. Comparisons of key elemental ratios and conservative tracers will be presented.

  3. Aerosol size distribution in a uranium processing and fuel fabrication facility.

    PubMed

    Prasad, K Vishwa; Balbudhe, A Y; Srivastava, G K; Tripathi, R M; Puranik, V D

    2010-08-01

    In the nuclear fuel complex, magnesium diuranate is processed to produce UO(2) through different chemical and metallurgical processes. UO(2) powder is compacted to produce uranium pallets as fuel. International Commission on Radiological Protection has considered default particle size of 5-mum activity median aerodynamic diameter (AMAD) and 2.5 of geometric standard deviation (GSD) for working out dose coefficients. There is a likelihood of variation in the particle size during each stage of operation. The present study is undertaken to determine the prevailing uranium aerosol size distribution at every stage of operation using Anderson impactor with glass fibre filter paper as collection substrate. AMAD and respective GSD were determined. Aerosol size distribution was studied. Airborne uranium concentration was found to be higher for higher particle sizes in all areas. Average AMAD for different locations varied from 5.8 to 7.7 mum with GSD from 1.63 to 6.73 and the ratio of calculated ALI to standard varies from 1.13 to 1.55. PMID:20406743

  4. Effects of explosively venting aerosol-sized particles through earth-containment systems on the cloud-stabilization height

    SciTech Connect

    Dyckes, G.W.

    1980-07-01

    A method of approximating the cloud stabilization height for aerosol-sized particles vented explosively through earth containment systems is presented. The calculated values for stabilization heights are in fair agreement with those obtained experimentally.

  5. Multisensor analyzer detector (MSAD) for low cost chemical and aerosol detection and pattern fusion

    NASA Astrophysics Data System (ADS)

    Swanson, David C.; Merdes, Daniel W.; Lysak, Daniel B., Jr.; Curtis, Richard C.; Lang, Derek C.; Mazzara, Andrew F.; Nicholas, Nicholas C.

    2002-08-01

    MSAD is being developed as a low-cost point detection chemical and biological sensor system designed around an information fusion inference engine that also allows additional sensors to be included in the detection process. The MSAD concept is based on probable cause detection of hazardous chemical vapors and aerosols of either chemical or biological composition using a small portable unit containing an embedded computer system and several integrated sensors with complementary capabilities. The configuration currently envisioned includes a Surface-Enhanced Raman Spectroscopy (SERS) sensor of chemical vapors and a detector of respirable aerosols based on Fraunhofer diffraction. Additional sensors employing Ion Mobility Spectrometry (IMS), Surface Acoustic Wave (SAW) detection, Flame Photometric Detection (FPD), and other principles are candidates for integration into the device; also, available commercial detectors implementing IMS, SAW, and FPD will be made accessible to the unit through RS232 ports. Both feature and decision level information fusion is supported using a Continuous Inference Network (CINET) of fuzzy logic. Each class of agents has a unique CINET with information inputs from a number of available sensors. Missing or low confidence sensor information is gracefully blended out of the output confidence for the particular agent. This approach constitutes a plug and play arrangement between the sensors and the information pattern recognition algorithms. We are currently doing simulant testing and developing out CINETs for actual agent testing at Edgewood Chemical and Biological Center (ECBC) later this year.

  6. Aerosol Size, CCN, and Black Carbon Properties at a Coastal Site in the Eastern U.S.

    NASA Astrophysics Data System (ADS)

    Royalty, T. M.; Petters, M. D.; Grieshop, A. P.; Meskhidze, N.; Reed, R. E.; Phillips, B.; Dawson, K. W.

    2015-12-01

    Atmospheric aerosols play an important role in regulating the global radiative budget through direct and indirect effects. To date, the role of sea spray aerosols in modulating climate remains poorly understood. Here we present results from measurements performed at the United States Army Corps of Engineers' Field Research Facility in Duck, North Carolina, USA. Aerosol mobility size distributions (10-600 nm), refractory black carbon (rBC) and scattering particle size distributions (200-620 nm), and size resolved cloud condensation nuclei distributions (.07% - .6% supersaturation) were collected at the end of a 560m pier. Aerosol characteristics associated with northerly, high wind speed (15+ m s-1) flow originating from an oceanic trajectory are contrasted with aerosol properties observed during a weak to moderate westerly flow originating from a continental trajectory. Both marine and continental air masses had aerosol with bi-modal number size distributions with modes centered at 30nm and 140nm. In the marine air-mass, the CCN concentration at supersaturation of 0.4%, total aerosol number, surface, and volume concentration were low. rBC number concentration (D > 200 nm) associated with the marine air-mass was an order of magnitude less than continental number concentration and indicative of relatively unpolluted air. These measurements are consistent with measurements from other coastal sites under marine influence. The relative proportion of Aitken mode size particles increased from 1:2 to 2:1 while aerosol surface area was < 25 μm2 cm-3, suggesting that conditions upwind were potentially conducive to new particle formation. Overall, these results will contribute a better understanding to composition and size variation of marine aerosols.

  7. Size-resolved morphological properties of the high Arctic summer aerosol during ASCOS-2008

    NASA Astrophysics Data System (ADS)

    Hamacher-Barth, Evelyne; Leck, Caroline; Jansson, Kjell

    2016-05-01

    The representation of aerosol properties and processes in climate models is fraught with large uncertainties. Especially at high northern latitudes a strong underprediction of aerosol concentrations and nucleation events is observed and can only be constrained by in situ observations based on the analysis of individual aerosol particles. To further reduce the uncertainties surrounding aerosol properties and their potential role as cloud condensation nuclei this study provides observational data resolved over size on morphological and chemical properties of aerosol particles collected in the summer high Arctic, north of 80° N. Aerosol particles were imaged with scanning and transmission electron microscopy and further evaluated with digital image analysis. In total, 3909 aerosol particles were imaged and categorized according to morphological similarities into three gross morphological groups: single particles, gel particles, and halo particles. Single particles were observed between 15 and 800 nm in diameter and represent the dominating type of particles (82 %). The majority of particles appeared to be marine gels with a broad Aitken mode peaking at 70 nm and accompanied by a minor fraction of ammonium (bi)sulfate with a maximum at 170 nm in number concentration. Gel particles (11 % of all particles) were observed between 45 and 800 nm with a maximum at 154 nm in diameter. Imaging with transmission electron microscopy allowed further morphological discrimination of gel particles in "aggregate" particles, "aggregate with film" particles, and "mucus-like" particles. Halo particles were observed above 75 nm and appeared to be ammonium (bi)sulfate (59 % of halo particles), gel matter (19 %), or decomposed gel matter (22 %), which were internally mixed with sulfuric acid, methane sulfonic acid, or ammonium (bi)sulfate with a maximum at 161 nm in diameter. Elemental dispersive X-ray spectroscopy analysis of individual particles revealed a prevalence of the monovalent

  8. Concentrations, size distributions and temporal variations of fluorescent biological aerosol particles in southern tropical India

    NASA Astrophysics Data System (ADS)

    Valsan, Aswathy; Krishna R, Ravi; CV, Biju; Huffman, Alex; Poschl, Ulrich; Gunthe, Sachin

    2015-04-01

    Biological aerosols constitute a wide range of dead and alive biological materials and structures that are suspended in the atmosphere. They play an important role in the atmospheric physical, chemical and biological processes and health of living being by spread of diseases among humans, plants, and, animals. The atmospheric abundance, sources, physical properties of PBAPs as compared to non-biological aerosols, however, is poorly characterized. The Indian tropical region, where large fraction of the world's total population is residing, experiences a distinctive meteorological phenomenon by means of Indian Summer Monsoon (IMS). Thus, the properties and characteristics of biological aerosols are also expected to be very diverse over the Indian subcontinent depending upon the seasons. Here we characterize the number concentration and size distribution of Fluorescent Biological Aerosol Particles (FBAP) at a high altitude continental site, Munnar (10.09 N, 77.06 E; 1605 m asl) in South India during the South-West monsoon, which constitute around 80 percent of the annual rainfall in Munnar. Continuous three months measurements (from 01 June 2014 to 21 Aug 2104) FBAPs were carried out at Munnar using Ultra Violet Aerodynamic Particle Sizer (UVAPS) during IMS. The mean number and mass concentration of coarse FBAP averaged over the entire campaign was 1.7 x 10-2 cm-3 and 0.24 µg m-3 respectively, which corresponds to 2 percent and 6 percent of total aerosol particle number and mass concentration. In agreement to other previous measurements the number size distribution of FBAP also peaks at 3.2 micron indicating the strong presence of fungal spores. This was also supported by the Scanning Electron Microscopic analysis of bioaerosols on filter paper. They also displayed a strong diurnal cycle with maximum concentration occurring at early morning hours. During periods of heavy and continuous rain where the wind is consistently blowing from South-West direction it was

  9. Size-separated sampling and analysis of isocyanates in workplace aerosols. Part I. Denuder--cascade impactor sampler.

    PubMed

    Dahlin, Jakob; Spanne, Mårten; Karlsson, Daniel; Dalene, Marianne; Skarping, Gunnar

    2008-07-01

    Isocyanates in the workplace atmosphere are typically present both in gas and particle phase. The health effects of exposure to isocyanates in gas phase and different particle size fractions are likely to be different due to their ability to reach different parts in the respiratory system. To reveal more details regarding the exposure to isocyanate aerosols, a denuder-impactor (DI) sampler for airborne isocyanates was designed. The sampler consists of a channel-plate denuder for collection of gaseous isocyanates, in series with three-cascade impactor stages with cut-off diameters (d(50)) of 2.5, 1.0 and 0.5 mum. An end filter was connected in series after the impactor for collection of particles smaller than 0.5 mum. The denuder, impactor plates and the end filter were impregnated with a mixture of di-n-butylamine (DBA) and acetic acid for derivatization of the isocyanates. During sampling, the reagent on the impactor plates and the end filter is continuously refreshed, due to the DBA release from the impregnated denuder plates. This secures efficient derivatization of all isocyanate particles. The airflow through the sampler was 5 l min(-1). After sampling, the samples containing the different size fractions were analyzed using liquid chromatography-mass spectrometry (LC-MS)/MS. The DBA impregnation was stable in the sampler for at least 1 week. After sampling, the DBA derivatives were stable for at least 3 weeks. Air sampling was performed in a test chamber (300 l). Isocyanate aerosols studied were thermal degradation products of different polyurethane polymers, spraying of isocyanate coating compounds and pure gas-phase isocyanates. Sampling with impinger flasks, containing DBA in toluene, with a glass fiber filter in series was used as a reference method. The DI sampler showed good compliance with the reference method, regarding total air levels. For the different aerosols studied, vast differences were revealed in the distribution of isocyanate in gas and

  10. Electrical Mobility Spectrometer Using a Diethylene Glycol Condensation Particle Counter for Measurement of Aerosol Size Distributions Down to 1 nm

    SciTech Connect

    Jiang, J.; Kuang, C.; Chen, M.; Attoui, M.; McMurry, P. H.

    2011-02-01

    We report a new scanning mobility particle spectrometer (SMPS) for measuring number size distributions of particles down to {approx}1 nm mobility diameter. This SMPS includes an aerosol charger, a TSI 3085 nano differential mobility analyzer (nanoDMA), an ultrafine condensation particle counter (UCPC) using diethylene glycol (DEG) as the working fluid, and a conventional butanol CPC (the 'booster') to detect the small droplets leaving the DEG UCPC. The response of the DEG UCPC to negatively charged sodium chloride particles with mobility diameters ranging from 1-6 nm was measured. The sensitivity of the DEG UCPC to particle composition was also studied by comparing its response to positively charged 1.47 and 1.70 nm tetra-alkyl ammonium ions, sodium chloride, and silver particles. A high resolution differential mobility analyzer was used to generate the test particles. These results show that the response of this UCPC to sub-2 nm particles is sensitive to particle composition. The applicability of the new SMPS for atmospheric measurement was demonstrated during the Nucleation and Cloud Condensation Nuclei (NCCN) field campaign (Atlanta, Georgia, summer 2009). We operated the instrument at saturator and condenser temperatures that allowed the efficient detection of sodium chloride particles but not of air ions having the same mobility. We found that particles as small as 1 nm were detected during nucleation events but not at other times. Factors affecting size distribution measurements, including aerosol charging in the 1-10 nm size range, are discussed. For the charger used in this study, bipolar charging was found to be more effective for sub-2 nm particles than unipolar charging. No ion induced nucleation inside the charger was observed during the NCCN campaign.

  11. Atmosphere Analyzer

    NASA Technical Reports Server (NTRS)

    1982-01-01

    California Measurements, Inc.'s model PC-2 Aerosol Particle Analyzer is produced in both airborne and ground-use versions. Originating from NASA technology, it is a quick and accurate method of detecting minute amounts of mass loadings on a quartz crystal -- offers utility as highly sensitive detector of fine particles suspended in air. When combined with suitable air delivery system, it provides immediate information on the size distribution and mass concentrations of aerosols. William Chiang, obtained a NASA license for multiple crystal oscillator technology, and initially developed a particle analyzer for NASA use with Langley Research Center assistance. Later his company produced the modified PC-2 for commercial applications Brunswick Corporation uses the device for atmospheric research and in studies of smoke particles in Fires. PC-2 is used by pharmaceutical and chemical companies in research on inhalation toxicology and environmental health. Also useful in testing various filters for safety masks and nuclear installations.

  12. Charge and size distribution of mesospheric aerosol particles measured inside NLC and PMSE during MIDAS MaCWAVE 2002

    NASA Astrophysics Data System (ADS)

    Smiley, B.; Rapp, M.; Blix, T. A.; Robertson, S.; Horányi, M.; Latteck, R.; Fiedler, J.

    2006-01-01

    During the MIDAS MaCWAVE sounding rocket campaign performed at Andøya, Norway (16°E, 69°N), from 29 June to 5 July 2002, charged aerosol probes aboard a MIDAS rocket detected a mixture of charged aerosol particles with different charges and sizes. Two charged aerosol probes were used on the MIDAS payload. The first probe, a collection surface shielded by a magnetic field, was optimized for the detection of negative aerosol particles. The second probe, a collection surface shielded by a magnetic field and a positive bias voltage, was optimized for detecting positive aerosol particles. On 2 July 2002, a MIDAS payload was launched into a simultaneous noctilucent cloud (NLC) and polar mesospheric summer echo (PMSE). The two probes measured a charge and size distribution of aerosol particles: a narrow layer of both small (1 nmaerosol particles inside the NLC, and also a broad layer of small (1 nmaerosol particles spread across the lower portion of the PMSE that reached maximum density inside the NLC.

  13. Distribution of 7Be, 210Pb and 210Po in Size Fractionated Aerosols From Northern Taiwan

    NASA Astrophysics Data System (ADS)

    Su, C.; Huh, C.

    2003-12-01

    The partition of 7Be, 210Pb and 210Po in size fractionated aerosols was studied using samples collected from Nankang (northern Taiwan) during July 2002-July 2003. A TSP air sampler coupled to a 6-stage cascade impactor was used to collect large-volume samples and separate the aerosols into six size classes with the cut-off points at 7.2 μ m, 3 μ m, 1.5 μ m, 0.95 μ m and 0.49 μ m. The total mass concentrations of the aerosol samples ranged from 23 to 99 μ g m-3, with a maximum (18-50 %) falling at the sixth stage (< 0.49 μ m) and a minimum (5-13 %) at the third stage (1.5-3.0 μ m). Total concentrations of 7Be, 210Pb and 210Po in the samples were 0.11-0.56, 0.012-0.100 and 0.0009-0.0158 dpm m-3, respectively. For most of the samples, more than 70 % of the radioactivities are found in the fifth and sixth stages (< 0.95 μ m). Concurrent with the measurements of 7Be and 210Pb concentrations in aerosols, we have also measured the fluxes of these nuclides. Coupling the concentration data with the flux data, we obtained an overall deposition velocity of 0.02-3.71 cm s-1 for 7Be and 0.09-6.18 cm s-1 for 210Pb, without any obvious seasonal variation during the experimental periods. The size of aerosol particles and the height of cloud are the major factors controlling the deposition velocity of 7Be and 210Pb. The time series of 210Po/210Pb was in phase with that of 7Be/210Pb and showed an increase during the spring and summer, probably reflecting stratospheric folding in the spring and more vigorous tropospheric mixing (e.g., due to typhoons) in the summer.

  14. Number size distribution measurements of biological aerosols under contrasting environments and seasons from southern tropical India

    NASA Astrophysics Data System (ADS)

    Valsan, Aswathy; Cv, Biju; Krishna, Ravi; Huffman, Alex; Poschl, Ulrich; Gunthe, Sachin

    2016-04-01

    Biological aerosols constitute a wide range of dead and alive biological materials and structures that are suspended in the atmosphere. They play an important role in the atmospheric physical, chemical and biological processes and health of living being by spread of diseases among humans, plants, and, animals. The atmospheric abundance, sources, physical properties of PBAPs as compared to non-biological aerosols, however, is poorly characterized. Though omnipresent, their concentration and composition exhibit large spatial and temporal variations depending up on their sources, land-use, and local meteorology. The Indian tropical region, which constitutes approximately 18% of the world's total population exhibits vast geographical extend and experiences a distinctive meteorological phenomenon by means of Indian Summer Monsoon (IMS). Thus, the sources, properties and characteristics of biological aerosols are also expected to have significant variations over the Indian subcontinent depending upon the location and seasons. Here we present the number concentration and size distribution of Fluorescent Biological Aerosol Particles (FBAP) from two contrasting locations in Southern tropical India measured during contrasting seasons using Ultra Violet Aerodynamic Particle Sizer (UV-APS). Measurements were carried out at a pristine high altitude continental site, Munnar (10.09 N, 77.06 E; 1605 m asl) during two contrasting seasons, South-West Monsoon (June-August, 2014) and winter (Jan - Feb, 2015) and in Chennai, a coastal urban area, during July - November 2015. FBAP concentrations at both the locations showed large variability with higher concentrations occurring at Chennai. Apart from regional variations, the FBAP concentrations also exhibited variations over two different seasons under the same environmental condition. In Munnar the FBAP concentration increased by a factor of four from South-West Monsoon to winter season. The average size distribution of FBAP at both

  15. Confining capillary waves to control aerosol droplet size from surface acoustic wave nebulisation

    NASA Astrophysics Data System (ADS)

    Nazarzadeh, Elijah; Reboud, Julien; Wilson, Rab; Cooper, Jonathan M.

    Aerosols play a significant role in targeted delivery of medication through inhalation of drugs in a droplet form to the lungs. Delivery and targeting efficiencies are mainly linked to the droplet size, leading to a high demand for devices that can produce aerosols with controlled sizes in the range of 1 to 5 μm. Here we focus on enabling the control of the droplet size of a liquid sample nebulised using surface acoustic wave (SAW) generated by interdigitated transducers on a piezoelectric substrate (lithium niobate). The formation of droplets was monitored through a high-speed camera (600,000 fps) and the sizes measured using laser diffraction (Spraytec, Malvern Ltd). Results show a wide droplet size distribution (between 0.8 and 400 μm), while visual observation (at fast frame rates) revealed that the large droplets (>100 μm) are ejected due to large capillary waves (80 to 300 μm) formed at the free surface of liquid due to leakage of acoustic radiation of the SAWs, as discussed in previous literature (Qi et al. Phys Fluids, 2008). To negate this effect, we show that a modulated structure, specifically with feature sizes, typically 200 μm, prevents formation of large capillary waves by reducing the degrees of freedom of the system, enabling us to obtain a mean droplet size within the optimum range for drug delivery (<10 μm). This work was supported by an EPSRC grant (EP/K027611/1) and an ERC Advanced Investigator Award (340117-Biophononics).

  16. Note: Evaluation of slurry particle size analyzers for chemical mechanical planarization process.

    PubMed

    Jang, Sunjae; Kulkarni, Atul; Qin, Hongyi; Kim, Taesung

    2016-04-01

    In the chemical mechanical planarization (CMP) process, slurry particle size is important because large particles can cause defects. Hence, selection of an appropriate particle measuring system is necessary in the CMP process. In this study, a scanning mobility particle sizer (SMPS) and dynamic light scattering (DLS) were compared for particle size distribution (PSD) measurements. In addition, the actual particle size and shape were confirmed by transmission electron microscope (TEM) results. SMPS classifies the particle size according to the electrical mobility, and measures the particle concentration (single particle measurement). On the other hand, the DLS measures the particle size distribution by analyzing scattered light from multiple particles (multiple particle measurement). For the slurry particles selected for evaluation, it is observed that SMPS shows bi-modal particle sizes 30 nm and 80 nm, which closely matches with the TEM measurements, whereas DLS shows only single mode distribution in the range of 90 nm to 100 nm and showing incapability of measuring small particles. Hence, SMPS can be a better choice for the evaluation of CMP slurry particle size and concentration measurements. PMID:27131717

  17. Note: Evaluation of slurry particle size analyzers for chemical mechanical planarization process

    NASA Astrophysics Data System (ADS)

    Jang, Sunjae; Kulkarni, Atul; Qin, Hongyi; Kim, Taesung

    2016-04-01

    In the chemical mechanical planarization (CMP) process, slurry particle size is important because large particles can cause defects. Hence, selection of an appropriate particle measuring system is necessary in the CMP process. In this study, a scanning mobility particle sizer (SMPS) and dynamic light scattering (DLS) were compared for particle size distribution (PSD) measurements. In addition, the actual particle size and shape were confirmed by transmission electron microscope (TEM) results. SMPS classifies the particle size according to the electrical mobility, and measures the particle concentration (single particle measurement). On the other hand, the DLS measures the particle size distribution by analyzing scattered light from multiple particles (multiple particle measurement). For the slurry particles selected for evaluation, it is observed that SMPS shows bi-modal particle sizes 30 nm and 80 nm, which closely matches with the TEM measurements, whereas DLS shows only single mode distribution in the range of 90 nm to 100 nm and showing incapability of measuring small particles. Hence, SMPS can be a better choice for the evaluation of CMP slurry particle size and concentration measurements.

  18. Real-time characterization of the size and chemical composition of individual particles in ambient aerosol systems in Riverside, California

    SciTech Connect

    Noble, C.A.; Prather, K.A.

    1995-12-31

    Atmospheric aerosols, although ubiquitous, are highly diverse and continually fluctuating systems. A typical aerosol system may consist of particles with diameters between {approximately}0.002 {mu}m and {approximately}200 {mu}m. Even in rural or pristine areas, atmospheric particle concentration is significant, with concentrations up to 10{sup 8} particles/cm{sup 3} not being uncommon. Chemical composition of atmospheric particles vary from simple water droplets or acidic ices to soot particles and cigarette smoke. Due to changes in atmospheric conditions, processes such as nucleation, coagulation or heterogeneous chemistry may effect both physical and chemical properties of individual particles over relatively short time intervals. Recently, aerosol measurement techniques are focusing on determining the size and/or chemical composition of individual aerosol particles. This research group has recently developed aerosol time-of-flight mass spectrometry (ATOFMS), a technique which allows for real-time determination of the size and chemical composition of individual aerosol particles. Single particle measurements are performed in one instrument using dual laser aerodynamic particle sizing and time-of-flight mass spectrometry. Aerosol-time-of-flight mass spectrometry is briefly described in several other abstracts in this publication.

  19. Multi-peak accumulation and coarse modes observed from AERONET retrieved aerosol volume size distribution in Beijing

    NASA Astrophysics Data System (ADS)

    Zhang, Ying; Li, Zhengqiang; Zhang, Yuhuan; Chen, Yu; Cuesta, Juan; Ma, Yan

    2016-01-01

    We present characteristic peaks of atmospheric columnar aerosol volume size distribution retrieved from the AErosol RObotic NETwork (AERONET) ground-based Sun-sky radiometer observation, and their correlations with aerosol optical properties and meteorological conditions in Beijing over 2013. The results show that the aerosol volume particle size distribution (VPSD) can be decomposed into up to four characteristic peaks, located in accumulation and coarse modes, respectively. The mean center radii of extra peaks in accumulation and coarse modes locate around 0.28 (±0.09) to 0.38 (±0.11) and 1.25 (±0.56) to 1.47 (±0.30) μm, respectively. The multi-peak size distributions are found in different aerosol loading conditions, with the mean aerosol optical depth (440 nm) of 0.58, 0.49, 1.18 and 1.04 for 2-, 3-I/II and 4-peak VPSD types, while the correspondingly mean relative humidity values are 58, 54, 72 and 67 %, respectively. The results also show the significant increase (from 0.25 to 0.40 μm) of the mean extra peak median radius in the accumulation mode for the 3-peak-II cases, which agrees with aerosol hygroscopic growth related to relative humidity and/or cloud or fog processing.

  20. Multi-peak accumulation and coarse modes observed from AERONET retrieved aerosol volume size distribution in Beijing

    NASA Astrophysics Data System (ADS)

    Zhang, Ying; Li, Zhengqiang; Zhang, Yuhuan; Chen, Yu; Cuesta, Juan; Ma, Yan

    2016-08-01

    We present characteristic peaks of atmospheric columnar aerosol volume size distribution retrieved from the AErosol RObotic NETwork (AERONET) ground-based Sun-sky radiometer observation, and their correlations with aerosol optical properties and meteorological conditions in Beijing over 2013. The results show that the aerosol volume particle size distribution (VPSD) can be decomposed into up to four characteristic peaks, located in accumulation and coarse modes, respectively. The mean center radii of extra peaks in accumulation and coarse modes locate around 0.28 (±0.09) to 0.38 (±0.11) and 1.25 (±0.56) to 1.47 (±0.30) μm, respectively. The multi-peak size distributions are found in different aerosol loading conditions, with the mean aerosol optical depth (440 nm) of 0.58, 0.49, 1.18 and 1.04 for 2-, 3-I/II and 4-peak VPSD types, while the correspondingly mean relative humidity values are 58, 54, 72 and 67 %, respectively. The results also show the significant increase (from 0.25 to 0.40 μm) of the mean extra peak median radius in the accumulation mode for the 3-peak-II cases, which agrees with aerosol hygroscopic growth related to relative humidity and/or cloud or fog processing.

  1. Aerosol Light Absorption and Scattering Assessments and the Impact of City Size on Air Pollution

    NASA Astrophysics Data System (ADS)

    Paredes-Miranda, Guadalupe

    The general problem of urban pollution and its relation to the city population is examined in this dissertation. A simple model suggests that pollutant concentrations should scale approximately with the square root of city population. This model and its experimental evaluation presented here serve as important guidelines for urban planning and attainment of air quality standards including the limits that air pollution places on city population. The model was evaluated using measurements of air pollution. Optical properties of aerosol pollutants such as light absorption and scattering plus chemical species mass concentrations were measured with a photoacoustic spectrometer, a reciprocal nephelometer, and an aerosol mass spectrometer in Mexico City in the context of the multinational project "Megacity Initiative: Local And Global Research Observations (MILAGRO)" in March 2006. Aerosol light absorption and scattering measurements were also obtained for Reno and Las Vegas, NV USA in December 2008-March 2009 and January-February 2003, respectively. In all three cities, the morning scattering peak occurs a few hours later than the absorption peak due to the formation of secondary photochemically produced aerosols. In particular, for Mexico City we determined the fraction of photochemically generated secondary aerosols to be about 75% of total aerosol mass concentration at its peak near midday. The simple 2-d box model suggests that commonly emitted primary air pollutant (e.g., black carbon) mass concentrations scale approximately as the square root of the urban population. This argument extends to the absorption coefficient, as it is approximately proportional to the black carbon mass concentration. Since urban secondary pollutants form through photochemical reactions involving primary precursors, in linear approximation their mass concentration also should scale with the square root of population. Therefore, the scattering coefficient, a proxy for particulate matter

  2. Point and column aerosol radiative closure during ACE 1: Effects of particle shape and size

    NASA Astrophysics Data System (ADS)

    Fridlind, A. M.; Jacobson, M. Z.

    2003-02-01

    We used data collected during the First Aerosol Characterization Experiment (ACE 1) to study point and column aerosol radiative closure over the remote ocean. To test point closure, total and hemispheric backscattering coefficients calculated with a Mie single-scattering model were compared with measurements made by ship and aircraft at three wavelengths (400, 550, and 700 nm). On the ship, assuming spherical particles, calculated total scattering was usually within 10% of measurements (closure obtained in >80% of the cases) but calculated backscattering was usually 15-25% lower than measurements (closure obtained in <50% of the cases). When a model for particle nonsphericity was applied to the dried sea spray, assuming the particles to be ideal cubes or irregular convex and concave crystals resulted in overestimation of backscattering. However, when nonsphericity parameters were fit to the measurements, calculated backscattering was also usually within 10% of measurements (closure obtained in >80% of the cases). On the aircraft, however, calculated scattering and backscattering were usually lower than measurements by 20-45% regardless of assumed particle shape (closure obtained in <50% of the cases), likely owing to differences in the aerosol inlet penetration efficiencies to each instrument or unidentified uncertainties in the measured number size distributions or scattering coefficients. To test column closure, aerosol extinction profiles calculated from in situ observations (below 5.5 km) and satellite observations (above 5.5 km) were vertically integrated, and the resulting aerosol optical depth was compared with measurements made on the ship during two clear-sky days at three wavelengths (500, 778, and 862 nm). Calculated spectral optical depths were usually within 25% of measurements (closure obtained at one or more wavelengths on both days), and agreement at longer wavelengths was improved when satellite measurements were spectrally scaled using in situ

  3. Dynamics of Particle Size on Inhalation of Environmental Aerosol and Impact on Deposition Fraction.

    PubMed

    Haddrell, Allen E; Davies, James F; Reid, Jonathan P

    2015-12-15

    Inhalation of elevated levels of particulate air pollution has been shown to elicit the onset of adverse health effects in humans, where the magnitude of the response is a product of where in the lung the particulate dose is delivered. At any point in time during inhalation the depositional flux of the aerosol is a function of the radius of the droplet, thus a detailed understanding of the rate and magnitude of the mass flux of water to the droplet during inhalation is crucial. In this study, we assess the impact of aerosol hygroscopicity on deposited dose through the inclusion of a detailed treatment of the mass flux of water to account for the dynamics of particle size in a modified version of the standard International Commission on Radiological Protection (ICRP) whole lung deposition model. The ability to account for the role of the relative humidity (RH) of the aerosol prior to, and during, inhalation on the deposition pattern is explored, and found to have a significant effect on the deposition pattern. The model is verified by comparison to previously published measurements, and used to demonstrate that ambient RH affects where in the lung indoor particulate air pollution is delivered. PMID:26568475

  4. Size stabilization of surface-supported liquid aerosols using tapered optical fiber coupling.

    PubMed

    Karadag, Yasin; Jonáš, Alexandr; Kucukkara, Ibrahim; Kiraz, Alper

    2013-03-01

    We demonstrate long-term size stabilization of surface-supported liquid aerosols of salt-water. Single tapered optical fibers were used to couple the light from independent heating and probe lasers into individual microdroplets that were kept on a superhydrophobic surface in a high-humidity chamber. Size stabilization of microdroplets resulted from competition between resonant absorption of the infrared heating laser by a microdroplet whispering gallery mode and water condensation in the sample chamber. Microdroplet size was continuously monitored using the tunable red probe laser. Thanks to the narrow linewidth of the heating laser, stabilization of the 110 μm radius of a microdroplet with a precision down to 0.54 nm was achieved for a period of 410 s. PMID:23455301

  5. Size-differentiated composition of the arctic aerosol at NY-Ålesund, Spitsbergen

    NASA Astrophysics Data System (ADS)

    Pacyna, Joseph M.; Vitols, Val; Hanssen, Jan Erik

    The aerosol composition, as a function of particle size, has been studied at Ny-Ålesund, Spitsbergen, during winter 1983. The concentrations of Si, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Ga, Br, Rb, Sr and Pb have been measured in samples from a 6-stage cascade impactor of Battelle design by particle-induced X-ray emission (PIXE). Two groups of concentration vs size distribution curves seem to emerge for the anthropogenic components. The first group appears to represent size distributions during 'normal' meteorological conditions, while the second one during episodes. Enrichment factors, calculated for all measured fractions of particles, gave information on possible anthropogenic contributions. Large differences in concentrations and enrichment factors of the anthropogenic elements in the fractions below 0.5 μm EAD (equivalent aerodynamic diameter) for the normal and episodic conditions could be used to assess the origins of the Arctic aerosol. The assessment was based on the spatial distributions of emissions, and the meteorological conditions, recorded during the measurement period. It was found that an episode probably occurred at Ny-Ålesund in March 1983. The episode resulted in very high concentrations of some elements in a portion of the fine fraction of particles. It is hypothesised that the origin of pollutants was the emission sources along the Urals and on the Kola Peninsula in the Soviet Union.

  6. Software for retrieval of aerosol particle size distribution from multiwavelength lidar signals

    NASA Astrophysics Data System (ADS)

    Sitarek, S.; Stacewicz, T.; Posyniak, M.

    2016-02-01

    Software to retrieve profiles of aerosol particle size distribution (APSD) from multiwavelength lidar signals is presented. The approach consists in direct fit of artificial signal generated using predefined distribution to the experimental signals. Combination of two lognormal functions with a few free parameters is applied for the predefined APSD. The minimization technique allows finding lognormal function parameters which provide the best fit. The approach was tested on the experimental signals registered at 1064, 532 and 355 nm. The software is designated for processing on PCs. The computation time was about several minutes.

  7. Five-years of atmospheric aerosol number size distribution measurements in Eastern Mediterranean

    NASA Astrophysics Data System (ADS)

    Kalivitis, Nikolaos; Kouvarakis, Giorgos; Bougiatioti, Aikaterini; Stavroulas, Iasonas; Wiedensohler, Alfred; Mihalopoulos, Nikolaos

    2014-05-01

    The first long term measurements of atmospheric particle size distributions from the Eastern Mediterranean region are reported. Atmospheric aerosol number size distributions have been measured at the environmental research station of University of Crete at Finokalia, Crete, Greece (35° 20' N, 25° 40' E, 250m a.s.l) on a continuous base since 2008. A custom built (TROPOS type) scanning mobility particle sizer (SMPS) is used covering size ranges from 8 to 900 nm. The system is humidity controlled so that relative humidity is kept below 40% most of the time. Throughout the measuring period the average number concentration of the particles in the studied size range was found to be 2354 ± 1332 cm-3 (median of 2098 cm-3). Maximum concentrations are observed during summer while minimum during winter, reflecting the effectiveness of the removal processes in the region. Clear annual circles are found for the number concentrations of nucleation, Aitken and accumulation mode particles. Nucleation mode is presenting different pattern from the other two modes, with the highest concentrations during winter (and March) and the lowest during summer. New particle formation events are more frequently observed during March and October. The number size distributions present different seasonal patterns. During summer, unimodal distributions centering on the lower end of the accumulation mode size range are dominant in our observations. The prevailing meteorology characterized by the Etesian winds (Meltemi) and the lack of precipitation along the trajectory results to the arrival of well mixed air masses at Finokalia, carrying aged aerosol mainly from central and Eastern Europe. Regarding the other seasons, the shape of the distributions is more variable and strongly dependent on the air mass history: When the air masses are of marine origin or precipitation has affected them, the size distributions are mainly bimodal (peaking both in Aitken and in Accumulation mode). These

  8. A radial differential mobility analyzer for the size-classification of gas-phase synthesized nanoparticles at low pressures

    NASA Astrophysics Data System (ADS)

    Nanda, K. K.; Kruis, F. E.

    2014-07-01

    Differential mobility analyzers (DMAs) are commonly used to generate monodisperse nanoparticle aerosols. Commercial DMAs operate at quasi-atmospheric pressures and are therefore not designed to be vacuum-tight. In certain particle synthesis methods, the use of a vacuum-compatible DMA is a requirement as a process step for producing high-purity metallic particles. A vacuum-tight radial DMA (RDMA) has been developed and tested at low pressures. Its performance has been evaluated by using a commercial NANO-DMA as the reference. The performance of this low-pressure RDMA (LP-RDMA) in terms of the width of its transfer function is found to be comparable with that of other NANO-DMAs at atmospheric pressure and is almost independent of the pressure down to 30 mbar. It is shown that LP-RDMA can be used for the classification of nanometer-sized particles (5-20 nm) under low pressure condition (30 mbar) and has been successfully applied to nanoparticles produced by ablating FeNi at low pressures.

  9. Mass loading of size-segregated atmospheric aerosols in the ambient air during fireworks episodes in eastern Central India.

    PubMed

    Nirmalkar, Jayant; Deb, Manas K; Deshmukh, Dhananjay K; Verma, Santosh K

    2013-04-01

    The effects of combustion of the fire crackers on the air quality in eastern Central India were studied for the first time during Diwali festival. This case study analyzes the size distribution and temporal variation of aerosols collected in the rural area of eastern Central India during pre-diwali, Diwali and post-diwali period for the year of 2011. Fifteen aerosol samples were collected during the special case study of Diwali period using Andersen sampler. The mean concentrations of PM10 (respirable particulate matter) were found to be 212.8 ± 4.2, 555.5 ± 20.2 and 284.4 ± 5.8 during pre-diwali, Diwali and post-diwali period, respectively. During Diwali festival PM10 concentration was about 2.6 and 1.9 times higher than pre-diwali and post-diwali period, respectively. PM2.5 (fine) and PM1 (submicron) concentrations during Diwali festival were more than 2 times higher than pre-diwali and post-diwali. PMID:23287842

  10. Silicon Wafer Cleaning Using New Liquid Aerosol with Controlled Droplet Velocity and Size by Rotary Atomizer Method

    NASA Astrophysics Data System (ADS)

    Seike, Yoshiyuki; Miyachi, Keiji; Shibata, Tatsuo; Kobayashi, Yoshinori; Kurokawa, Syuhei; Doi, Toshiro

    2010-06-01

    A liquid aerosol, which sprays cleaning liquid with a carrier gas, is widely used for cleaning semiconductor devices. The liquid aerosol using a conventional two-fluid nozzle may cause pattern damage on the wafer. To resolve this problem, we have made a prototype new rotary atomizing two-fluid cleaning nozzle (RAC nozzle), which can control the velocity distribution and size distribution of flying liquid droplets separately. It was confirmed by measuring flying liquid droplets using a shadow Doppler particle analyzer system that the mean volumetric diameter of the droplets could be atomized to 20 µm or less at a rotational speed of the air turbine of 50,000 min-1 and that the mean velocity of the flying liquid droplets could be controlled in the range under 65 m/s independently. It was confirmed in a cleaning experiment using polystyrene latex (PSL) particles on a wafer that particle removal efficiency increased when shaping air pressure increased. Also, the particle removal efficiency was improved with the finer atomization promoted by a higher rotational speed of the air turbine.

  11. Silicon Wafer Cleaning Using New Liquid Aerosol with Controlled Droplet Velocity and Size by Rotary Atomizer Method

    NASA Astrophysics Data System (ADS)

    Yoshiyuki Seike,; Keiji Miyachi,; Tatsuo Shibata,; Yoshinori Kobayashi,; Syuhei Kurokawa,; Toshiro Doi,

    2010-06-01

    A liquid aerosol, which sprays cleaning liquid with a carrier gas, is widely used for cleaning semiconductor devices. The liquid aerosol using a conventional two-fluid nozzle may cause pattern damage on the wafer. To resolve this problem, we have made a prototype new rotary atomizing two-fluid cleaning nozzle (RAC nozzle), which can control the velocity distribution and size distribution of flying liquid droplets separately. It was confirmed by measuring flying liquid droplets using a shadow Doppler particle analyzer system that the mean volumetric diameter of the droplets could be atomized to 20 μm or less at a rotational speed of the air turbine of 50,000 min-1 and that the mean velocity of the flying liquid droplets could be controlled in the range under 65 m/s independently. It was confirmed in a cleaning experiment using polystyrene latex (PSL) particles on a wafer that particle removal efficiency increased when shaping air pressure increased. Also, the particle removal efficiency was improved with the finer atomization promoted by a higher rotational speed of the air turbine.

  12. The evolution of biomass-burning aerosol size distributions due to coagulation: dependence on fire and meteorological details and parameterization

    NASA Astrophysics Data System (ADS)

    Sakamoto, Kimiko M.; Laing, James R.; Stevens, Robin G.; Jaffe, Daniel A.; Pierce, Jeffrey R.

    2016-06-01

    Biomass-burning aerosols have a significant effect on global and regional aerosol climate forcings. To model the magnitude of these effects accurately requires knowledge of the size distribution of the emitted and evolving aerosol particles. Current biomass-burning inventories do not include size distributions, and global and regional models generally assume a fixed size distribution from all biomass-burning emissions. However, biomass-burning size distributions evolve in the plume due to coagulation and net organic aerosol (OA) evaporation or formation, and the plume processes occur on spacial scales smaller than global/regional-model grid boxes. The extent of this size-distribution evolution is dependent on a variety of factors relating to the emission source and atmospheric conditions. Therefore, accurately accounting for biomass-burning aerosol size in global models requires an effective aerosol size distribution that accounts for this sub-grid evolution and can be derived from available emission-inventory and meteorological parameters. In this paper, we perform a detailed investigation of the effects of coagulation on the aerosol size distribution in biomass-burning plumes. We compare the effect of coagulation to that of OA evaporation and formation. We develop coagulation-only parameterizations for effective biomass-burning size distributions using the SAM-TOMAS large-eddy simulation plume model. For the most-sophisticated parameterization, we use the Gaussian Emulation Machine for Sensitivity Analysis (GEM-SA) to build a parameterization of the aged size distribution based on the SAM-TOMAS output and seven inputs: emission median dry diameter, emission distribution modal width, mass emissions flux, fire area, mean boundary-layer wind speed, plume mixing depth, and time/distance since emission. This parameterization was tested against an independent set of SAM-TOMAS simulations and yields R2 values of 0.83 and 0.89 for Dpm and modal width, respectively. The

  13. Increase of Cloud Droplet Size with Aerosol Optical Depth: An Observational and Modeling Study

    SciTech Connect

    Yuan, Tianle; Li, Zhanqing; Zhang, Renyi; Fan, Jiwen

    2008-02-21

    Cloud droplet effective radius (DER) is generally negatively correlated with aerosol optical depth (AOD) as a proxy of cloud condensation nuclei. In this study, cases of positive correlation were found over certain portions of the world by analyzing the Moderate Resolution Imaging Spectroradiometer (MODIS) satellite products, together with a general finding that DER may increase or decrease with aerosol loading depending on environmental conditions. The slope of the correlation between DER and AOD is driven primarily by water vapor amount, which explains 70% of the variance in our study. Various potential artifacts that may cause the positive relation are investigated including water vapor swelling, partially cloudy, atmospheric dynamics, cloud three-dimensional (3-D) and surface influence effects. None seems to be the primary cause for the observed phenomenon, although a certain degree of influence exists for some of the factors. Analyses are conducted over seven regions around the world representing different types of aerosols and clouds. Only two regions show positive dependence of DER on AOD, near coasts of the Gulf of Mexico and South China Sea, which implies physical processes may at work. Using a 2-D spectral-bin microphysics Goddard Cumulus Ensemble model (GCE) which incorporated a reformulation of the Köhler theory, two possible physical mechanisms are hypothesized. They are related to the effects of slightly soluble organics (SSO) particles and giant CCNs. Model simulations show a positive correlation between DER and AOD, due to a decrease in activated aerosols with an increasing SSO content. Addition of a few giant CCNs also increases the DER. Further investigations are needed to fully understand and clarify the observed phenomenon.

  14. Response characteristics of laser diffraction particle size analyzers - Optical sample volume extent and lens effects

    NASA Technical Reports Server (NTRS)

    Hirleman, E. D.; Oechsle, V.; Chigier, N. A.

    1984-01-01

    The response characteristics of laser diffraction particle sizing instruments were studied theoretically and experimentally. In particular, the extent of optical sample volume and the effects of receiving lens properties were investigated in detail. The experimental work was performed with a particle size analyzer using a calibration reticle containing a two-dimensional array of opaque circular disks on a glass substrate. The calibration slide simulated the forward-scattering characteristics of a Rosin-Rammler droplet size distribution. The reticle was analyzed with collection lenses of 63 mm, 100 mm, and 300 mm focal lengths using scattering inversion software that determined best-fit Rosin-Rammler size distribution parameters. The data differed from the predicted response for the reticle by about 10 percent. A set of calibration factor for the detector elements was determined that corrected for the nonideal response of the instrument. The response of the instrument was also measured as a function of reticle position, and the results confirmed a theoretical optical sample volume model presented here.

  15. Particle size distribution and inorganic aerosol characterization during DAURE 2009 winter field campaign at Montseny site

    NASA Astrophysics Data System (ADS)

    Aranzazu Revuelta, M.; Gómez-Moreno, Francisco J.; Plaza, Javier; Coz, Esther; Pey, Jorge; Cusack, Michael; Pandolfi, Marco; Rodríguez-Maroto, Jesús J.; Pujadas, Manuel

    2010-05-01

    During DAURE 2009 winter field campaign, one of the sampling sites was Montseny, a rural background station located 40 km NNE from Barcelona and 25 km W from the Mediterranean Sea. It is a Natural Park and a protected area, thus with low human activity, mainly agriculture. The sampling station was located on a valley with it axis oriented on the direction NW-SE. At this site, a TSI-SMPS (DMA 3071 and CPC 3022) was installed in order to measure the particle number distribution in the size range 15-600 nm during the period March 19-27 with a measurement cycle of 12 minutes The particle mass distribution was measured by a micro-orifice uniform deposit impactor (MOUDI) using eleven size stages with aluminum substrates and a quartz fiber backup filter. Four samples were taken during the period 13-19 March, two during 24 hours and other two during 48 hours. This impactor has a wider size range allowing to measure from 56 to 18000 nm. The substrates and filters obtained were later analyzed for determining soluble ions (sulfate, nitrate, ammonium and calcium) by IC. There are mainly two different kinds of events measured with the SMPS. When the air masses were coming from SE, which meant that they could come from the park but also from the urban and industrial areas located in the pre-coastal depression, it was characterized by higher particle number concentrations and by size distributions centered on 80 nm. This meant it was an aged aerosol, which had grown up by coagulation, condensation and oxidation processes. When the air masses were coming from NW (the second valley axis side), the particle measured were much smaller, the instrument started to detect particles with 15 nm, but smaller ones could be possible. This meant that new particle nucleation could have occurred in the valley, just before arriving to the sampling point. From MOUDI samplings, two different types of events were also observed. Three of the four samplings coincided with stagnation of air masses or

  16. Simplifying aerosol size distributions modes simultaneously detected at four monitoring sites during SAPUSS

    NASA Astrophysics Data System (ADS)

    Brines, M.; Dall'Osto, M.; Beddows, D. C. S.; Harrison, R. M.; Querol, X.

    2014-03-01

    The analysis of aerosol size distributions is a useful tool for understanding the sources and the processes influencing particle number concentrations (N) in urban areas. Hence, during the one-month SAPUSS campaign (Solving Aerosol Problems by Using Synergistic Strategies, EU Marie Curie Action) in autumn 2010 in Barcelona (Spain), four SMPSs (Scanning Mobility Particle Sizer) were simultaneously deployed at four monitoring sites: a road side (RSsite), an urban background site located in the city (UBsite), an urban background site located in the nearby hills of the city (Torre Collserola, TCsite) and a regional background site located about 50 km from the Barcelona urban areas (RBsite). The spatial distribution of sites allows study of the aerosol temporal variability as well as the spatial distribution, progressively moving away from urban aerosol sources. In order to interpret the data sets collected, a k-means cluster analysis was performed on the combined SMPS data sets. This resulted in nine clusters describing all aerosol size distributions from the four sites. In summary there were three main categories (with three clusters in each category): "Traffic" (Traffic 1, "Tclus_1" - 8%; Traffic 2, "Tclus_2" - 13%; and Traffic 3, "Tclus_3" - 9%) "Background Pollution" (Urban Background 1, "UBclus_1" - 21%; Regional Background 1, "RBclus_1" - 15%; and Regional Background 2, "RBclus_2" - 18%) and "Special Cases" (Nucleation, "NUclus" - 5%; Regional Nitrate, "NITclus" - 6%; and Mix, "MIXclus" - 5%). As expected, the frequency of traffic clusters (Tclus_1-3) followed the order RSsite, UBsite, TCsite, and RBsite. These showed typical traffic modes mainly distributed at 20-40 nm. The urban background sites (UBsite and TCsite) reflected also as expected urban background number concentrations (average values, N = 1.0 × 104 cm-3 and N = 5.5 × 103 cm-3, respectively, relative to 1.3 × 104 cm-3 seen at RSsite). The cluster describing the urban background pollution (UBclus_1

  17. Effect of ethanol on droplet size, efficiency of delivery, and clearance characteristics of technetium-99m DTPA aerosol.

    PubMed

    Sirr, S A; Juenemann, P J; Tom, H; Boudreau, R J; Chandler, R P; Loken, M K

    1985-06-01

    With recent technical advances in aerosol technology, the study of regional ventilation using [99mTc]DTPA aerosol has become increasingly popular. Using a cascade impactor, we have assessed droplet size distribution from a newly designed nebulizer. Delivery efficiency of [99mTc]DTPA aerosol to normal subjects was improved 70% with a 10% concentration of ethanol in the nebulizer. Using filter paper fixed to the delivery end of the aerosol device, and varying ethanol concentrations from 0-10%, an 87% increase of deposited radioactivity is measured. Use of higher concentration of ethanol to the nebulizer solution did not further improve delivery efficiency. The addition of ethanol did not alter clearance characteristics of [99mTc]DTPA from the lung nor did it affect droplet size distribution. PMID:3889235

  18. Effect of ethanol on droplet size, efficiency of delivery, and clearance characteristics of technetium-99m DTPA aerosol

    SciTech Connect

    Sirr, S.A.; Juenemann, P.J.; Tom, H.; Boudreau, R.J.; Chandler, R.P.; Loken, M.K.

    1985-06-01

    With recent technical advances in aerosol technology, the study of regional ventilation using (/sup 99m/Tc)DTPA aerosol has become increasingly popular. Using a cascade impactor, the authors have assessed droplet size distribution from a newly designed nebulizer. Delivery efficiency of (/sup 99m/Tc)DTPA aerosol to normal subjects was improved 70% with a 10% concentration of ethanol in the nebulizer. Using filter paper fixed to the delivery end of the aerosol device, and varying ethanol concentrations from 0-10%, an 87% increase of deposited radioactivity is measured. The addition of ethanol did not alter clearance characteristics of (/sup 99m/Tc)DTPA from the lung nor did it affect droplet size distribution.

  19. A size-composition resolved aerosol model for simulating the dynamics of externally mixed particles: SCRAM (v 1.0)

    NASA Astrophysics Data System (ADS)

    Zhu, S.; Sartelet, K. N.; Seigneur, C.

    2015-06-01

    The Size-Composition Resolved Aerosol Model (SCRAM) for simulating the dynamics of externally mixed atmospheric particles is presented. This new model classifies aerosols by both composition and size, based on a comprehensive combination of all chemical species and their mass-fraction sections. All three main processes involved in aerosol dynamics (coagulation, condensation/evaporation and nucleation) are included. The model is first validated by comparison with a reference solution and with results of simulations using internally mixed particles. The degree of mixing of particles is investigated in a box model simulation using data representative of air pollution in Greater Paris. The relative influence on the mixing state of the different aerosol processes (condensation/evaporation, coagulation) and of the algorithm used to model condensation/evaporation (bulk equilibrium, dynamic) is studied.

  20. Emission factors of carbon monoxide and size-resolved aerosols from biofuel combustion.

    PubMed

    Venkataraman, C; Rao, G U

    2001-05-15

    This study reports emission factors of carbon monoxide and size-resolved aerosols from combustion of wood, dung cake, and biofuel briquette in traditional and improved stoves in India. Wood was the cleanest burning fuel, with higher emissions of CO from dung cake and particulate matter from both dung cake and briquette fuels. Combustion of dung cake, especially in an improved metal stove, resulted in extremely high pollutant emissions. Instead, biogas from anaerobic dung digestion should be promoted as a cooking fuel for public health protection. Pollutant emissions increased with increasing stove thermal efficiency, implying that thermal efficiency enhancement in the improved stoves was mainly from design features leading to increased heat transfer but not combustion efficiency. Compared to the traditional stove, the improved stoves resulted in the lower pollutant emissions on a kW h-1 basis from wood combustion but in similar emissions from briquette and dung cake. Stove designs are needed with good emissions performance across multiple fuels. Unimodal aerosol size distributions were measured from biofuel combustion with mass median aerodynamic diameters of 0.5-0.8 micron, about a factor of 10 larger than those from fossil fuel combustion (e.g. diesel), with potential implications for lung deposition and health risk. PMID:11393993

  1. Using high time resolution aerosol and number size distribution measurements to estimate atmospheric extinction.

    PubMed

    Malm, William C; McMeeking, Gavin R; Kreidenweis, Sonia M; Levin, Ezra; Carrico, Christian M; Day, Derek E; Collett, Jeffrey L; Lee, Taehyoung; Sullivan, Amy P; Raja, Suresh

    2009-09-01

    Rocky Mountain National Park is experiencing reduced visibility and changes in ecosystem function due to increasing levels of oxidized and reduced nitrogen. The Rocky Mountain Atmospheric Nitrogen and Sulfur (RoMANS) study was initiated to better understand the origins of sulfur and nitrogen species as well as the complex chemistry occurring during transport from source to receptor. As part of the study, a monitoring program was initiated for two 1-month time periods--one during the spring and the other during late summer/fall. The monitoring program included intensive high time resolution concentration measurements of aerosol number size distribution, inorganic anions, and cations, and 24-hr time resolution of PM2.5 and PM10 mass, sulfate, nitrate, carbon, and soil-related elements concentrations. These data are combined to estimate high time resolution concentrations of PM2.5 and PM10 aerosol mass and fine mass species estimates of ammoniated sulfate, nitrate, and organic and elemental carbon. Hour-by-hour extinction budgets are calculated by using these species concentration estimates and measurements of size distribution and assuming internal and external particle mixtures. Summer extinction was on average about 3 times higher than spring extinction. During spring months, sulfates, nitrates, carbon mass, and PM10 - PM2.5 mass contributed approximately equal amounts of extinction, whereas during the summer months, carbonaceous material extinction was 2-3 times higher than other species. PMID:19785272

  2. Laboratory Testing and Calibration of the Nuclei-Mode Aerosol Size Spectrometer

    NASA Technical Reports Server (NTRS)

    Brock, Charles A.

    1999-01-01

    This grant was awarded to complete testing and calibration of a new instrument, the nuclei-mode aerosol size spectrometer (N-MASS), following its use in the WB-57F Aerosol Measurement (WAM) campaign in early 1998. The N-MASS measures the size distribution of particles in the 4-60 nm diameter range with 1-Hz response at typical free tropospheric conditions. Specific tasks to have been completed under the auspices of this award were: 1) to experimentally determine the instrumental sampling efficiency; 2) to determine the effects of varying temperatures and flows on N-MASS performance; and 3) to calibrate the N-MASS at typical flight conditions as operated in WAM. The work outlined above has been completed, and a journal manuscript based on this work and that describes the performance of the N-MASS is in preparation. Following a brief description of the principles of operation of the instrument, the major findings of this study are described.

  3. Isotope source apportionment of carbonaceous aerosol as a function of particle size and thermal refractiveness

    NASA Astrophysics Data System (ADS)

    Masalaite, Agne; Holzinger, Rupert; Remeikis, Vidmantas; Röckmann, Thomas; Dusek, Ulrike

    2016-04-01

    The stable carbon isotopes can be used to get information about sources and processing of carbonaceous aerosol. We will present results from source apportionment of carbonaceous aerosol as a function of particle size thermal refractiveness. Separate source apportionment for particles smaller than 200 nm and for different carbon volatility classes are rarely reported and give new insights into aerosol sources in the urban environment. Stable carbon isotope ratios were measured for the organic carbon (OC) fraction and total carbon (TC) of MOUDI impactor samples that were collected on a coastal site (Lithuania) during the winter 2012 and in the city of Vilnius (Lithuania) during the winter of 2009. The 11 impactor stages spanned a size range from 0.056 to 18 μm, but only the 6 stages in the submicron range were analysed. The δ13C values of bulk total carbon (δ13CTC) were determined with an elemental analyser (Flash EA 1112) coupled with an isotope ratio mass spectrometer (Thermo Finnigan Delta Plus Advantage) (EA - IRMS). Meanwhile δ13COC was measured using thermal-desorption isotope ratio mass spectrometry (IRMS) system. This allows a rough separation of the more volatile OC fraction (desorbed in the oven of IRMS up to 250 0C) from the more refractory fraction (desorbed up to 400 0C). In this study we investigated the composition of organic aerosol desorbed from filter samples at different temperatures using the thermal-desorption proton-transfer-reaction mass spectrometry (TD-PTR-MS) technique. During winter-time in Lithuania we expect photochemistry and biogenic emissions to be of minor importance. The main sources of aerosol carbon should be fossil fuel and biomass combustion. In both sites, the coastal and the urban site, δ13C measurements give a clear indication that the source contributions differ for small and large particles. Small particles < 200 nm are depleted in 13C with respect to larger particles by 1 - 2 ‰Ṫhis shows that OC in small particle

  4. Characteristics of size-segregated carbonaceous aerosols in the Beijing-Tianjin-Hebei region.

    PubMed

    Guo, Yuhong

    2016-07-01

    Mass concentrations of organic carbon (OC) and elemental carbon (EC) in size-resolved aerosols were investigated at four sites (three cities and one country) in the Beijing-Tianjin-Hebei region from September 2009 to August 2011. The size distributions of OC and EC presented large evolutions among rural and urban sites, and among four seasons, with highest peaks of OC and EC in fine mode in urban areas during winter. Geometric mean diameters (GMDs) of OC and EC in fine particles at urban sites during winter were lower than those at rural site mainly due to effects of fine particle coagulation and organic compound repartitioning. Fossil fuel emissions were a dominant source of OC and EC in urban areas, while biomass burning was a major source of OC and EC at rural site. Trajectory clustering and CWT analysis showed that regional transport was an important contributor to OC and EC in Beijing. PMID:27040539

  5. Aerosol concentration and size distribution measured below, in, and above cloud from the DOE G-1 during VOCALS-REx

    SciTech Connect

    Kleinman, L.I.; Daum, P. H.; Lee, Y.-N.; Lewis, E. R.; Sedlacek III, A. J.; Senum, G. I.; Springston, S. R.; Wang, J.; Hubbe, J.; Jayne, J.; Min, Q.; Yum, S. S.; Allen, G.

    2011-06-21

    During the VOCALS Regional Experiment, the DOE G-1 aircraft was used to sample a varying aerosol environment pertinent to properties of stratocumulus clouds over a longitude band extending 800 km west from the Chilean coast at Arica. Trace gas and aerosol measurements are presented as a function of longitude, altitude, and dew point in this study. Spatial distributions are consistent with an upper atmospheric source for O{sub 3} and South American coastal sources for marine boundary layer (MBL) CO and aerosol, most of which is acidic sulfate in agreement with the dominant pollution source being SO{sub 2} from Cu smelters and power plants. Pollutant layers in the free troposphere (FT) can be a result of emissions to the north in Peru or long range transport from the west. At a given altitude in the FT (up to 3 km), dew point varies by 40 C with dry air descending from the upper atmospheric and moist air having a BL contribution. Ascent of BL air to a cold high altitude results in the condensation and precipitation removal of all but a few percent of BL water along with aerosol that served as CCN. Thus, aerosol volume decreases with dew point in the FT. Aerosol size spectra have a bimodal structure in the MBL and an intermediate diameter unimodal distribution in the FT. Comparing cloud droplet number concentration (CDNC) and pre-cloud aerosol (Dp > 100 nm) gives a linear relation up to a number concentration of {approx}150 cm{sup -3}, followed by a less than proportional increase in CDNC at higher aerosol number concentration. A number balance between below cloud aerosol and cloud droplets indicates that {approx}25% of aerosol in the PCASP size range are interstitial (not activated). One hundred and two constant altitude cloud transects were identified and used to determine properties of interstitial aerosol. One transect is examined in detail as a case study. Approximately 25 to 50% of aerosol with D{sub p} > 110 nm were not activated, the difference between the two

  6. Aerosol concentration and size distribution measured below, in, and above cloud from the DOE G-1 during VOCALS-REx

    NASA Astrophysics Data System (ADS)

    Kleinman, L. I.; Daum, P. H.; Lee, Y.-N.; Lewis, E. R.; Sedlacek, A. J., III; Senum, G. I.; Springston, S. R.; Wang, J.; Hubbe, J.; Jayne, J.; Min, Q.; Yum, S. S.; Allen, G.

    2011-06-01

    During the VOCALS Regional Experiment, the DOE G-1 aircraft was used to sample a varying aerosol environment pertinent to properties of stratocumulus clouds over a longitude band extending 800 km west from the Chilean coast at Arica. Trace gas and aerosol measurements are presented as a function of longitude, altitude, and dew point in this study. Spatial distributions are consistent with an upper atmospheric source for O3 and South American coastal sources for marine boundary layer (MBL) CO and aerosol, most of which is acidic sulfate in agreement with the dominant pollution source being SO2 from Cu smelters and power plants. Pollutant layers in the free troposphere (FT) can be a result of emissions to the north in Peru or long range transport from the west. At a given altitude in the FT (up to 3 km), dew point varies by 40 °C with dry air descending from the upper atmospheric and moist air having a BL contribution. Ascent of BL air to a cold high altitude results in the condensation and precipitation removal of all but a few percent of BL water along with aerosol that served as CCN. Thus, aerosol volume decreases with dew point in the FT. Aerosol size spectra have a bimodal structure in the MBL and an intermediate diameter unimodal distribution in the FT. Comparing cloud droplet number concentration (CDNC) and pre-cloud aerosol (Dp > 100 nm) gives a linear relation up to a number concentration of ~150 cm-3, followed by a less than proportional increase in CDNC at higher aerosol number concentration. A number balance between below cloud aerosol and cloud droplets indicates that ~25 % of aerosol in the PCASP size range are interstitial (not activated). One hundred and two constant altitude cloud transects were identified and used to determine properties of interstitial aerosol. One transect is examined in detail as a case study. Approximately 25 to 50 % of aerosol with Dp > 110 nm were not activated, the difference between the two approaches possibly representing

  7. Molecular-level Analysis of Size Resolved Secondary Organic Aerosol (SOA) Samples from CALNEX Bakersfield Using High Resolution Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    O'Brien, R. E.; Laskin, A.; Laskin, J.; Weber, R.; Goldstein, A. H.

    2011-12-01

    This project focuses on analyzing the identities of molecules that comprise oligomers in size resolved aerosol fractions. Since oligomers are generally too large and polar to be measured by typical GC/MS analysis, soft ionization with high resolution mass spectrometry is used to extend the range of observable compounds. Samples collected with a microorifice uniform deposition impactor (MOUDI) during CALNEX Bakersfield in June 2010 have been analyzed with nanospray desorption electrospray ionization (nano-DESI) and an Orbitrap mass spectrometer. The nano-DESI is a soft ionization technique that allows molecular ions to be observed and the Orbitrap has sufficient resolution to determine the elemental composition of almost all species above the detection limit. A large fraction of SOA is made up of high molecular weight oligomers which are thought to form through acid catalyzed reactions of photo-chemically processed volatile organic compounds (VOC). The formation of oligomers must be influenced by the VOCs available, the amount of atmospheric sulfate and nitrate, and the magnitude of photo-chemical processing, among other potential influences. We present the elemental composition of chemical species in SOA in the 0.18 to 0.32 micron size range, providing the first multi-day data set for the study of these oligomers in atmospheric samples. Possible formation pathways and sources of observed compounds will be examined by comparison to other concurrent measurements at the site.

  8. Aerosol concentration and size distribution measured below, in, and above cloud from the DOE G-1 during VOCALS-REx

    SciTech Connect

    Kleinman L. I.; Daum, P. H.; Lee, Y.-N.; Lewis, E. R.; Sedlacek III, A. J.; Senum, G. I.; Springston, S. R.; Wang, J.; Hubbe, J.; Jayne, J.; Min, Q.; Yum, S. S.; Allen, G.

    2012-01-04

    During the VOCALS Regional Experiment, the DOE G-1 aircraft was used to sample a varying aerosol environment pertinent to properties of stratocumulus clouds over a longitude band extending 800 km west from the Chilean coast at Arica. Trace gas and aerosol measurements are presented as a function of longitude, altitude, and dew point in this study. Spatial distributions are consistent with an upper atmospheric source for O{sub 3} and South American coastal sources for marine boundary layer (MBL) CO and aerosol, most of which is acidic sulfate. Pollutant layers in the free troposphere (FT) can be a result of emissions to the north in Peru or long range transport from the west. At a given altitude in the FT (up to 3 km), dew point varies by 40 C with dry air descending from the upper atmospheric and moist air having a boundary layer (BL) contribution. Ascent of BL air to a cold high altitude results in the condensation and precipitation removal of all but a few percent of BL water along with aerosol that served as CCN. Thus, aerosol volume decreases with dew point in the FT. Aerosol size spectra have a bimodal structure in the MBL and an intermediate diameter unimodal distribution in the FT. Comparing cloud droplet number concentration (CDNC) and pre-cloud aerosol (D{sub p} > 100 nm) gives a linear relation up to a number concentration of {approx}150 cm{sup -3}, followed by a less than proportional increase in CDNC at higher aerosol number concentration. A number balance between below cloud aerosol and cloud droplets indicates that {approx}25 % of aerosol with D{sub p} > 100 nm are interstitial (not activated). A direct comparison of pre-cloud and in-cloud aerosol yields a higher estimate. Artifacts in the measurement of interstitial aerosol due to droplet shatter and evaporation are discussed. Within each of 102 constant altitude cloud transects, CDNC and interstitial aerosol were anti-correlated. An examination of one cloud as a case study shows that the

  9. Size distribution characteristics of carbonaceous aerosol in Xishuangbanna, southwest China: a sign for biomass burning in Asia.

    PubMed

    Guo, Yuhong

    2016-03-01

    In 2012, size-segregated aerosol samples were collected in Xishuangbanna, a forest station in southwest China. The concentrations of organic and elemental carbon (OC and EC for short) were quantified with thermal/optical carbon analyzer in the filter samples. OC and EC exhibited similar seasonal patterns, with the highest concentrations in spring, possibly due to the influence of biomass burning in south and southeast Asia. The mass size distributions of OC and EC were bimodal in all the sampling seasons, each with a dominant peak in the fine mode of 0.4-0.7 μm and a coarse peak in the size range of 2.1-4.7 μm. In fine mode, OC and EC showed smaller geometric mean diameters (GMDs) during winter. OC and EC were prone to be more concentrated in fine particles in spring and winter than in summer and autumn. Furthermore, EC was more abundant in fine particles than OC. Good correlations (R(2) = 0.75-0.82) between OC and EC indicated that they had common dominant sources of combustion such as biomass burning and fossil fuel combustion emissions. The daily average OC/EC ratios ranged from 2.1 to 9.1, more elevated OC/EC ratios being found in the winter. PMID:26851952

  10. Plume Aerosol Size Distribution Modeling and Comparisons to PrAIRie2005 Field Study Data

    NASA Astrophysics Data System (ADS)

    Cho, S.; Liggio, J.; Makar, P.; Li, S.; Racinthe, J.

    2006-12-01

    As part of the analysis phase of the PrAIRie2005 field study, the effects of different Edmonton-area emission sources on local air-quality are being examined. Four large coal-fired power-plants are located to the West of the city. Here, the effects of these power-plants on urban and regional air-quality will be examined, using both plume and regional air-quality models. During the last few decades, coal-fired power plants have been found to be as a major source of pollution, affecting public-health. According to NACEC (North American Commission for Environmental Corporation, 2001)'s report, 46 of the top 50 air polluters in North America were power plants. The importance of such sources has resulted in several attempts to improve understanding of the basic formation mechanisms of plume particulate matter. Sulphur dioxide contributes to acidifying emissions and to the production of secondary acidic aerosols that have been linked to a number of serious human health problems, acid rain and visibility (Seinfeld and Pandis, 1998; Hidy, 1984; Wilson and McMurray, 1981). Primary particulate matter originating directly from coal-fired power plants may also increase secondary particulate mass by providing a surface for sulphuric acid absorption . Environment Canada's PrAIRie2005 field study between August 12th and September 7th, 2005 included overflights and downwind measurements near the Edmonton powerplants (Wabamun, Sundance, Keephills and Genesee). The data collected consisted of particle size distributions, ozone, NOX, total mass and the chemical composition of fine particles. In order to investigate and improve our understanding of the formation mechanisms and physical properties of power-plant-generated aerosols in the Edmonton area, the Plume Aerosol Microphysical (PAM) model has been employed. This model accounts for gas-phase chemistry, aerosol microphysical processes (i.e. homogeneous/heterogeneous nucleation, condensation/evaporation and coagulation) and

  11. Mars Aerosol Studies with the MGS TES Emission Phase Function Observations: Opacities, Particle Sizes, and Ice Cloud Types

    NASA Astrophysics Data System (ADS)

    Wolff, M. J.; Clancy, R. T.; Pitman, K. M.; Christensen, P. R.; Whitney, B. A.

    2001-11-01

    A full Mars year (1999-2001) of emission phase function (EPF) observations from Mars Global Surveyor (MGS) Thermal Emission Spectrometer (TES) provide the most complete study of Mars dust and ice aerosol properties to date. TES visible (solar band average) and infrared spectral EPF sequences are analyzed self-consistently with detailed multiple scattering radiative transfer codes. As a consequence of the combined angular and wavelength coverage, we are able to define two distinct ice cloud types at 45\\arcdeg S-45\\arcdeg N latitudes on Mars. Type I ice clouds exhibit small particle sizes (1-2 \\micron\\ radii), as well as a broad, deep minimum in side-scattering that are potentially indicative of aligned ice grains. Type I ice aerosols are most prevalent in the southern hemisphere during Mars aphelion, but also appear more widely distributed in season and latitude as topographic and high altitude (>20 km) ice hazes. Type II ice clouds exhibit larger particle sizes (3-5 \\micron) and a much narrower side-scattering minimum, indicative of poorer grain alignment or a change in particle shape relative to the type I ice clouds. Type II ice clouds appear most prominently in the northern subtropical aphelion cloud belt, where relatively low altitudes water vapor saturation (10 km) coincide with strong advective transport. Retrieved dust particle radii of 1.5-1.8 \\micron\\ are consistent with Pathfinder and recent Viking/Mariner 9 reanalyses. Our analyses also find EPF-derived dust single scattering albedos (ssa) in agreement with those from Pathfinder. Spatial and seasonal changes in the dust ssa (0.92-0.95, solar band average) and phase functions suggest possible dust property variations, but may also be a consequence of variable high altitude ice hazes. The annual variations of both dust and ice clouds at 45S-45N latitudes are predominately orbital rather than seasonal in character and have shown remarkable repeatability during the portions of two Mars years observed

  12. Source apportionment of size and time resolved trace elements and organic aerosols from an urban courtyard site in Switzerland

    NASA Astrophysics Data System (ADS)

    Richard, A.; Gianini, M. F. D.; Mohr, C.; Furger, M.; Bukowiecki, N.; Minguillón, M. C.; Lienemann, P.; Flechsig, U.; Appel, K.; Decarlo, P. F.; Heringa, M. F.; Chirico, R.; Baltensperger, U.; Prévôt, A. S. H.

    2011-02-01

    Time and size resolved data of trace elements were obtained from measurements with a rotating drum impactor (RDI) and subsequent X-ray fluorescence spectrometry. Trace elements can act as indicators for the identification of sources of particulate matter <10 μm (PM10) in ambient air. Receptor modeling was performed with positive matrix factorization (PMF) for trace element data from an urban background site in Zürich, Switzerland. Eight different sources were identified for the three examined size ranges (PM1-0.1, PM2.5-1 and PM10-2.5): secondary sulfate, wood combustion, fire works, road traffic, mineral dust, de-icing salt, industrial and local anthropogenic activities. The major component was secondary sulfate for the smallest size range; the road traffic factor was found in all three size ranges. This trace element analysis is complemented with data from an Aerodyne high-resolution time-of-flight aerosol mass spectrometer (AMS), assessing the PM1 fraction of organic aerosols. A separate PMF analysis revealed three factors related to three of the sources found with the RDI: oxygenated organic aerosol (OOA, related to inorganic secondary sulfate), hydrocarbon like organic aerosol (HOA, related to road traffic) and biomass burning organic aerosol (BBOA), explaining 60%, 22% and 17% of total measured organics, respectively. Since different compounds are used for the source classification, a higher percentage of the ambient PM10 mass concentration can be apportioned to sources by the combination of both methods.

  13. Source apportionment of size and time resolved trace elements and organic aerosols from an urban courtyard site in Switzerland

    NASA Astrophysics Data System (ADS)

    Richard, A.; Gianini, M. F. D.; Mohr, C.; Furger, M.; Bukowiecki, N.; Minguillón, M. C.; Lienemann, P.; Flechsig, U.; Appel, K.; Decarlo, P. F.; Heringa, M. F.; Chirico, R.; Baltensperger, U.; Prévôt, A. S. H.

    2011-09-01

    Time and size resolved data of trace elements were obtained from measurements with a rotating drum impactor (RDI) and subsequent X-ray fluorescence spectrometry. Trace elements can act as indicators for the identification of sources of particulate matter <10 μm (PM10) in ambient air. Receptor modeling was performed with positive matrix factorization (PMF) for trace element data from an urban background site in Zürich, Switzerland. Eight different sources were identified for the three examined size ranges (PM1-0.1, PM2.5-1 and PM10-2.5): secondary sulfate, wood combustion, fire works, road traffic, mineral dust, de-icing salt, industrial and local anthropogenic activities. The major component was secondary sulfate for the smallest size range; the road traffic factor was found in all three size ranges. This trace element analysis is complemented with data from an Aerodyne high-resolution time-of-flight aerosol mass spectrometer (AMS), assessing the PM1 fraction of organic aerosols. A separate PMF analysis revealed three factors related to three of the sources found with the RDI: oxygenated organic aerosol (OOA, related to inorganic secondary sulfate), hydrocarbon-like organic aerosol (HOA, related to road traffic) and biomass burning organic aerosol (BBOA), explaining 60 %, 22 % and 17 % of total measured organics, respectively. Since different compounds are used for the source classification, a higher percentage of the ambient PM10 mass concentration can be apportioned to sources by the combination of both methods.

  14. Size distribution of aerosol particles produced during mining and processing uranium ore.

    PubMed

    Mala, Helena; Tomasek, Ladislav; Rulik, Petr; Beckova, Vera; Hulka, Jiri

    2016-06-01

    The aerosol particle size distributions of uranium and its daughter products were studied and determined in the area of the Rožná mine, which is the last active uranium mine in the Czech Republic. A total of 13 samples were collected using cascade impactors from three sites that had the highest expected levels of dust, namely, the forefield, the end of the ore chute and an area close to workers at the crushing plant. The characteristics of most size distributions were very similar; they were moderately bimodal, with a boundary approximately 0.5 μm between the modes. The activity median aerodynamic diameter (AMAD) and geometric standard deviation (GSD) were obtained from the distributions beyond 0.39 μm, whereas the sizes of particles below 0.39 μm were not differentiated. Most AMAD and GSD values in the samples ranged between 3.5 and 10.5 μm and between 2.8 and 5.0, respectively. The geometric means of the AMADs and GSDs from all of the underground sampling sites were 4.2 μm and 4.4, respectively, and the geometric means of the AMADs and GSDs for the crushing plant samplings were 9.8 μm and 3.3, respectively. The weighted arithmetic mean of the AMADs was 4.9 μm, with a standard error of 0.7 μm, according to the numbers of workers at the workplaces. The activity proportion of the radon progeny to (226)Ra in the aerosol was 0.61. PMID:27032340

  15. Size-resolved aerosol chemical concentrations at rural and urban sites in Central California, USA

    NASA Astrophysics Data System (ADS)

    Chow, Judith C.; Watson, John G.; Lowenthal, Douglas H.; Magliano, Karen L.

    2008-11-01

    Aerosol size distributions were measured with Micro Orifice Uniform Deposit Impactor (MOUDI) cascade impactors at the rural Angiola and urban Fresno Supersites in California's San Joaquin Valley during the California Regional PM 10/PM 2.5 Air Quality Study (CRPAQS) winter campaign from December 15, 2000 to February 3, 2001. PM 2.5 filter samples were collected concurrently at both sites with Sequential Filter Samplers (SFS). MOUDI nitrate (NO 3-) concentrations reached 66 μg/m 3 on January 6, 2001 during the 1000-1600 PST (GMT-8) period. Pair-wise comparisons between PM 2.5 MOUDI and SFS concentrations revealed high correlations at the Angiola site ( r > 0.93) but more variability ( r < 0.85) at the Fresno site for NO 3-, sulfate (SO 4=), and ammonium (NH 4+). Correlations were higher at Fresno ( r > 0.87) than at Angiola ( r < 0.7) for organic carbon (OC), elemental carbon (EC), and total carbon (TC). NO 3- and SO 4= size distributions in Fresno were multi-modal and wider than the uni-modal distributions observed at Angiola. Geometric mean diameters (GMD) were smaller for OC and EC than for NO 3- and SO 4= at both sites. OC and EC were more concentrated on the lowest MOUDI stage (0.056 µm) at Angiola than at Fresno. The NO 3- GMD increased from 0.97 to 1.02 µm as the NO 3- concentration at Angiola increased from 43 to 66 µg m - 3 during a PM 2.5 episode from January 4-7, 2001. There was a direct relationship between GMD and NO 3- and SO 4= concentrations at Angiola but no such relationships for OC or EC. This demonstrates that secondary aerosol formation increases both concentration and particle size for the rural California environment.

  16. 2008 springtime size-segregated aerosol composition observed in Seoul, Korea

    NASA Astrophysics Data System (ADS)

    Kim, S.; Lee, H.; Kim, J.; Cho, C.; Song, S.; Lim, J.; Kim, S.

    2008-12-01

    A total of 19 size-segregated particle samples were collected using two Micro-Orifice Uniform Deposit Impactors (MOUDI) in order to characterize aerosol chemical composition (mass, ions and elements) in the springtime of 2008 in Seoul, Korea. During the sampling period, there were three Asian Dust events in Seoul (March 16, April 3, and May 30-31). The average concentrations of PM10 and PM1.8 were 50.1±31.4 μg/m3 and 28.3±16.1μg/m3, respectively, with PM1.8/PM10 ratio of 0.61±0.15 indicating that fine particles dominated PM10 during the period. The high PM1.8/PM10 ratio might be explained by the location of sampling site which lies in the center of urban area. However, PM1.8/PM10 ratio was between 0.25 and 0.44 for Asian dust cases. According to our results, in general, aerosol mass concentration showed bimodal size distribution, peaked at the size range of 0.56-1μm in fine mode and 3.2-5.6μm in coarse mode. Ammonium, sulfate and nitrate ions were major components in fine mode (particles less than 1.8μm). However, unlike the other ions, nitrate ion showed peaks in both coarse mode and fine mode. Interestingly, on May 30(heavy Asian dust case), the highest nitrate ion concentration was observed in coarse mode rather than in fine mode.

  17. Final Report, The Influence of Organic-Aerosol Emissions and Aging on Regional and Global Aerosol Size Distributions and the CCN Number Budget

    SciTech Connect

    Donahue, Neil M.

    2015-12-23

    We conducted laboratory experiments and analyzed data on aging of organic aerosol and analysis of field data on volatility and CCN activity. With supplemental ASR funding we participated in the FLAME-IV campaign in Missoula MT in the Fall of 2012, deploying a two-chamber photochemical aging system to enable experimental exploration of photochemical aging of biomass burning emissions. Results from that campaign will lead to numerous publications, including demonstration of photochemical production of Brown Carbon (BrC) from secondary organic aerosol associated with biomass burning emissions as well as extensive characterization of the effect of photochemical aging on the overall concentrations of biomass burning organic aerosol. Excluding publications arising from the FLAME-IV campaign, project research resulted in 8 papers: [11, 5, 3, 10, 12, 4, 8, 7], including on in Nature Geoscience addressing the role of organic compounds in nanoparticle growth [11

  18. Aerosol size-dependent below-cloud sca venging by rain and snow in the ECHAM5-HAM

    NASA Astrophysics Data System (ADS)

    Croft, B.; Lohmann, U.; Martin, R. V.; Stier, P.; Wurzler, S.; Feichter, J.; Posselt, R.; Ferrachat, S.

    2009-07-01

    Wet deposition processes are highly efficient in the removal of aerosols from the atmosphere, and thus strongly influence global aerosol concentrations, and clouds, and their respective radiative forcings. In this study, physically detailed size-dependent below-cloud scavenging parameterizations for rain and snow are implemented in the ECHAM5-HAM global aerosol-climate model. Previously, below-cloud scavenging by rain in the ECHAM5-HAM was simply a function of the aerosol mode, and then scaled by the rainfall rate. The below-cloud scavenging by snow was a function of the snowfall rate alone. The global mean aerosol optical depth, and sea salt burden are sensitive to the below-cloud scavenging coefficients, with reductions near to 15% when the more vigorous size-dependent below-cloud scavenging by rain and snow is implemented. The inclusion of a prognostic rain scheme significantly reduces the fractional importance of below-cloud scavenging since there is higher evaporation in the lower troposphere, increasing the global mean sea salt burden by almost 15%. Thermophoretic effects are shown to produce increases in the global and annual mean number removal of Aitken size particles of near to 10%, but very small increases (near 1%) in the global mean below-cloud mass scavenging of carbonaceous and sulfate aerosols. Changes in the assumptions about the below-cloud scavenging by rain of particles with radius smaller than 10 nm do not cause any significant changes to the global and annual mean aerosol mass or number burdens, despite a change in the below-cloud number removal rate for nucleation mode particles by near to five-fold. Annual and zonal mean nucleation mode number concentrations are enhanced by up to 30% in the lower troposphere with the more vigourous size-dependent below-cloud scavenging. Closer agreement with different observations is found when the more physically detailed below-cloud scavenging parameterization is employed in the ECHAM5-HAM model.

  19. Linking aerosol size and optical properties to trace gases emitted from biomass burning in real-time

    NASA Astrophysics Data System (ADS)

    McMeeking, G. R.; Carrico, C. M.; Stockwell, C.; Yokelson, R. J.; Veres, P. R.; DeMott, P. J.; Kreidenweis, S. M.

    2014-12-01

    Biomass burning aerosols have large impacts on regional and global climate that are partly determined by their optical properties. The optical properties of aerosol depend on their size and composition, which in turn are related to fire combustion processes. Here we investigate relationships between a large suite of trace gases and aerosol size and optical properties to better understand processes governing the optical properties of fresh biomass burning aerosol emissions. We examined over 100 individual burns of biomass fuels during the Fire Laboratory at Missoula Experiment 4 (FLAME 4). Emissions were measured directly from an exhaust stack designed to capture all emissions from relatively small-scale fires burned at the base of a large burn chamber. Trace gas species were measured using a combination of an open-path Fourier transform infrared spectrometer (OP-FTIR) and proton-transfer mass spectrometer (PTR-MS). Aerosol optical properties at 870 nm were measured using a photoacoustic extinctiometer (PAX) and particle size distributions were measured using a Fast Mobility Particle Sizer (FMPS) and Aerodynamic Particle Sizer. The rapid response of the instruments allowed for comparisons of the emissions and particle properties over the duration of the fire. For example, we observed correlations between aerosol absorption, particle size, and gas-phase species associated with different types of combustion such as flaming and smoldering. We also report fire-integrated emissions for aerosol absorption and scattering coefficients and compare these to other fire-integrated properties. Many of our burn experiments examined a number of fuels that had not before been characterized in laboratory conditions, including a number of peat fuels, African savanna grasses and crop residuals.

  20. Aerosols and their sources at Summit Greenland - First results of continuous size- and time-resolved sampling

    NASA Astrophysics Data System (ADS)

    VanCuren, Richard A.; Cahill, Thomas; Burkhart, John; Barnes, David; Zhao, Yongjing; Perry, Kevin; Cliff, Steven; McConnell, Joe

    2012-06-01

    An ongoing program to continuously collect time- and size-resolved aerosol samples from ambient air at Summit Station, Greenland (72.6 N, 38.5 W) is building a long-term data base to both record individual transport events and provide long-term temporal context for past and future intensive studies at the site. As a "first look" at this data set, analysis of samples collected from summer 2005 to spring 2006 demonstrates the utility of continuous sampling to characterize air masses over the ice pack, document individual aerosol transport events, and develop a long-term record. Seven source-related aerosol types were identified in this analysis: Asian dust, Saharan dust, industrial combustion, marine with combustion tracers, fresh coarse volcanic tephra, and aged volcanic plume with fine tephra and sulfate, and the well-mixed background "Arctic haze". The Saharan dust is a new discovery; the other types are consistent with those reported from previous work using snow pits and intermittent ambient air sampling during intensive study campaigns. Continuous sampling complements the fundamental characterization of Greenland aerosols developed in intensive field programs by providing a year-round record of aerosol size and composition at all temporal scales relevant to ice core analysis, ranging from individual deposition events and seasonal cycles, to a record of inter-annual variability of aerosols from both natural and anthropogenic sources.

  1. Balloon-borne measurement of the aerosol size distribution from an Icelandic flood basalt eruption

    NASA Astrophysics Data System (ADS)

    Vignelles, D.; Roberts, T. J.; Carboni, E.; Ilyinskaya, E.; Pfeffer, M.; Dagsson Waldhauserova, P.; Schmidt, A.; Berthet, G.; Jegou, F.; Renard, J.-B.; Ólafsson, H.; Bergsson, B.; Yeo, R.; Fannar Reynisson, N.; Grainger, R. G.; Galle, B.; Conde, V.; Arellano, S.; Lurton, T.; Coute, B.; Duverger, Vincent

    2016-11-01

    We present in situ balloon-borne measurements of aerosols in a volcanic plume made during the Holuhraun eruption (Iceland) in January 2015. The balloon flight intercepted a young plume at 8 km distance downwind from the crater, where the plume is ∼15 min of age. The balloon carried a novel miniature optical particle counter LOAC (Light Optical Aerosol Counter) which measures particle number concentration and size distribution in the plume, alongside a meteorological payload. We discuss the possibility of calculating particle flux by combining LOAC data with measurements of sulfur dioxide flux by ground-based UV spectrometer (DOAS). The balloon passed through the plume at altitude range of 2.0-3.1 km above sea level (a.s.l.). The plume top height was determined as 2.7-3.1 km a.s.l., which is in good agreement with data from Infrared Atmospheric Sounding Interferometer (IASI) satellite. Two distinct plume layers were detected, a non-condensed lower layer (300 m thickness) and a condensed upper layer (800 m thickness). The lower layer was characterized by a lognormal size distribution of fine particles (0.2 μm diameter) and a secondary, coarser mode (2.3 μm diameter), with a total particle number concentration of around 100 cm-3 in the 0.2-100 μm detection range. The upper layer was dominated by particle centered on 20 μm in diameter as well as containing a finer mode (2 μm diameter). The total particle number concentration in the upper plume layer was an order of magnitude higher than in the lower layer. We demonstrate that intercepting a volcanic plume with a meteorological balloon carrying LOAC is an efficient method to characterize volcanic aerosol properties. During future volcanic eruptions, balloon-borne measurements could be carried out easily and rapidly over a large spatial area in order to better characterize the evolution of the particle size distribution and particle number concentrations in a volcanic plume.

  2. Size-specific composition of aerosols in the El Chichon volcanic cloud

    NASA Technical Reports Server (NTRS)

    Woods, D. C.; Chuan, R. L.

    1983-01-01

    A NASA U-2 research aircraft flew sampling missions in April, May, July, November, and December 1982 aimed at obtaining in situ data in the stratospheric cloud produced from the March-April 1982 El Chichon eruptions. Post flight analyses provided information on the aerosol composition and morphology. The particles ranged in size from smaller than 0.05 m to larger than 20 m diameter and were quite complex in composition. In the April, May, and July samples the aerosol mass was dominated by magmatic and lithic particles larger than about 3 m. The submicron particles consisted largely of sulfuric acid. Halite particles, believed to be related to a salt dome beneath El Chichon, were collected in the stratosphere in April and May. On the July 23 flight, copper-zinc oxide particles were collected. In July, November, and December, in addition to the volcanic ash and acid particles, carbon-rich particles smaller than about 0.1 m aerodynamic diameter were abundant.

  3. Size distribution, mixing state and source apportionments of black carbon aerosols in London during winter time

    NASA Astrophysics Data System (ADS)

    Liu, D.; Allan, J. D.; Young, D. E.; Coe, H.; Beddows, D.; Fleming, Z. L.; Flynn, M. J.; Gallagher, M. W.; Harrison, R. M.; Lee, J.; Prevot, A. S. H.; Taylor, J. W.; Yin, J.; Williams, P. I.; Zotter, P.

    2014-06-01

    Black carbon aerosols (BC) at a London urban site were characterized in both winter and summer time 2012 during the Clean Air for London (ClearfLo) project. Positive matrix factorization (PMF) factors of organic aerosol mass spectra measured by a high resolution aerosol mass spectrometer (HR-AMS) showed traffic-dominant sources in summer but in winter the influence of additional non-traffic sources became more important, mainly from solid fuel sources (SF). Measurements using a single particle soot photometer (SP2, DMT), showed the traffic-dominant BC exhibited an almost uniform BC core size (Dc) distribution with very thin coating thickness throughout the detectable range of Dc. However the size distribution of Dc (project average mass median Dc = 149 ± 22 nm in winter, and 120 ± 6 nm in summer) and BC coating thickness varied significantly in winter. A novel methodology was developed to attribute the BC number concentrations and mass abundances from traffic (BCtr) and from SF (BCsf), by using a 2-D histogram of the particle optical properties as a function of BC core size, as measured by the SP2. The BCtr and BCsf showed distinctly different Dc distributions and coating thicknesses, with BCsf displaying larger Dc and larger coating thickness compared to BCtr. BC particles from different sources were also apportioned by applying a multiple linear regression between the total BC mass and each AMS-PMF factor (BC-AMS-PMF method), and also attributed by applying the absorption spectral dependence of carbonaceous aerosols to 7-wavelength Aethalometer measurements (Aethalometer method). Air masses that originated from westerly (W), southeasterly (SE), or easterly (E) sectors showed BCsf fractions that ranged from low to high, and whose mass median Dc values were 137 ± 10 nm, 143 ± 11 nm, and 169 ± 29 nm respectively. The corresponding bulk relative coating thickness of BC (coated particle size / BC core - Dp / Dc) for these same sectors was 1.28 ± 0.07, 1.45 ± 0

  4. Size distribution, mixing state and source apportionment of black carbon aerosol in London during wintertime

    NASA Astrophysics Data System (ADS)

    Liu, D.; Allan, J. D.; Young, D. E.; Coe, H.; Beddows, D.; Fleming, Z. L.; Flynn, M. J.; Gallagher, M. W.; Harrison, R. M.; Lee, J.; Prevot, A. S. H.; Taylor, J. W.; Yin, J.; Williams, P. I.; Zotter, P.

    2014-09-01

    Black carbon aerosols (BC) at a London urban site were characterised in both winter- and summertime 2012 during the Clean Air for London (ClearfLo) project. Positive matrix factorisation (PMF) factors of organic aerosol mass spectra measured by a high-resolution aerosol mass spectrometer (HR-AMS) showed traffic-dominant sources in summer but in winter the influence of additional non-traffic sources became more important, mainly from solid fuel sources (SF). Measurements using a single particle soot photometer (SP2, DMT), showed the traffic-dominant BC exhibited an almost uniform BC core size (Dc) distribution with very thin coating thickness throughout the detectable range of Dc. However, the size distribution of sf (project average mass median Dc = 149 ± 22 nm in winter, and 120 ± 6 nm in summer) and BC coating thickness varied significantly in winter. A novel methodology was developed to attribute the BC number concentrations and mass abundances from traffic (BCtr) and from SF (BCsf), by using a 2-D histogram of the particle optical properties as a function of BC core size, as measured by the SP2. The BCtr and BCsf showed distinctly different sf distributions and coating thicknesses, with BCsf displaying larger Dc and larger coating thickness compared to BCtr. BC particles from different sources were also apportioned by applying a multiple linear regression between the total BC mass and each AMS-PMF factor (BC-AMS-PMF method), and also attributed by applying the absorption spectral dependence of carbonaceous aerosols to 7-wavelength Aethalometer measurements (Aethalometer method). Air masses that originated from westerly (W), southeasterly (SE), and easterly (E) sectors showed BCsf fractions that ranged from low to high, and whose mass median Dc values were 137 ± 10 nm, 143 ± 11 nm and 169 ± 29 nm, respectively. The corresponding bulk relative coating thickness of BC (coated particle size/BC core - Dp/Dc) for these same sectors was 1.28 ± 0.07, 1.45 ± 0

  5. Ultraviolet broadband light scattering for optically-trapped submicron-sized aerosol particles.

    PubMed

    David, Grégory; Esat, Kıvanç; Ritsch, Irina; Signorell, Ruth

    2016-02-21

    We describe a broadband light scattering setup for the characterization of size and refractive index of single submicron-to-micron sized aerosol particles. Individual particles are isolated in air by a quadruple Bessel beam optical trap or a counter-propagating optical tweezer. The use of very broadband radiation in the wavelength range from 320 to 700 nm covering the ultraviolet region allows to size submicron particles. We show that a broad wavelength range is required to determine the particle radius and the refractive index with an uncertainty of several nanometers and ∼ 0.01, respectively. The smallest particle radius that can be accurately determined lies around 300 nm. Wavelength-dependent refractive index data over a broad range are obtained, including the ultraviolet region where corresponding data are rare. Four different applications are discussed: (1) the sizing of submicron polystyrene latex spheres, (2) the evaporation of binary glycerol water droplets, (3) hydration/dehydration cycling of aqueous potassium carbonate droplets, and (4) photochemical reactions of oleic acid droplets. PMID:26863396

  6. Airship measurements of aerosol size distributions, cloud droplet spectra, and trace gas concentrations in the marine boundary layers

    SciTech Connect

    Frick, G.M.; Hoppel, W.A. )

    1993-11-01

    The use of an airship as a platform to conduct atmospheric chemistry, aerosol, and cloud microphysical research is described, and results from demonstration flights made off the Oregon coast are presented. The slow speed of the airship makes it an ideal platform to do high-spatial resolution profiling both vertically and horizontally, and to measure large aerosol and cloud droplet distributions without the difficulties caused by high-speed aircraft sampling. A unique set of data obtained during the demonstration flights show the effect that processing marine boundary layer aerosol through stratus clouds has on the aerosol size distribution. Evidence of new particle formation (nucleation of particles) was also observed on about half the days on which flights were made. 11 refs., 9 figs., 1 tab.

  7. The Influence of Hilly Terrain on Aerosol-Sized Particle Deposition into Forested Canopies

    NASA Astrophysics Data System (ADS)

    Katul, G. G.; Poggi, D.

    2010-04-01

    Virtually all reviews dealing with aerosol-sized particle deposition onto forested ecosystems stress the significance of topographic variations, yet only a handful of studies considered the effects of these variations on the deposition velocity ( V d ). Here, the interplay between the foliage collection mechanisms within a dense canopy for different particle sizes and the flow dynamics for a neutrally stratified boundary layer on a gentle and repeating cosine hill are considered. In particular, how topography alters the spatial structure of V d and its two constitutive components, particle fluxes and particle mean concentration within and immediately above the canopy, is examined in reference to a uniform flat-terrain case. A two-dimensional and particle-size resolving model based on first-order closure principles that explicitly accounts for (i) the flow dynamics, including the two advective terms, (ii) the spatial variation in turbulent viscosity, and (iii) the three foliage collection mechanisms that include Brownian diffusion, turbo-phoresis, and inertial impaction is developed and used. The model calculations suggest that, individually, the advective terms can be large just above the canopy and comparable to the canopy collection mechanisms in magnitude but tend to be opposite to each other in sign. Moreover, these two advective terms are not precisely out of phase with each other, and hence, do not readily cancel each other upon averaging across the hill wavelength. For the larger aerosol-sized particles, differences between flat-terrain and hill-averaged V d can be significant, especially in the layers just above the canopy. We also found that the hill-induced variations in turbulent shear stress, which are out-of-phase with the topography in the canopy sublayer, play a significant role in explaining variations in V d across the hill near the canopy top. Just after the hill summit, the model results suggest that V d fell to 30% of its flat terrain value for

  8. Detection, enumeration, and sizing of planktonic bacteria by image-analyzed epifluorescence microscopy.

    PubMed Central

    Sieracki, M E; Johnson, P W; Sieburth, J M

    1985-01-01

    Epifluorescence microscopy is now being widely used to characterize planktonic procaryote populations. The tedium and subjectivity of visual enumeration and sizing have been largely alleviated by our use of an image analysis system consisting of a modified Artek 810 image analyzer and an Olympus BHT-F epifluorescence microscope. This system digitizes the video image of autofluorescing or fluorochrome-stained cells in a microscope field. The digitized image can then be stored, edited, and analyzed for total count or individual cell size and shape parameters. Results can be printed as raw data, statistical summaries, or histograms. By using a stain concentration of 5 micrograms of 4'6-diamidino-2-phenylindole per ml of sample and the optimal sensitivity level and mode, counts by image analysis of natural bacterial populations from a variety of habitats were found to be statistically equal to standard visual counts. Although the time required to prepare slides, focus, and change fields is the same for visual and image analysis methods, the time and effort required for counting is eliminated since image analysis is instantaneous. The system has been satisfactorily tested at sea. Histograms of cell silhouette areas indicate that rapid and accurate estimates of bacterial biovolume and biomass will be possible with this system. Images PMID:2408564

  9. Organic composition of PM 2.5 and size-segregated aerosols and their sources during the 2002 Bay Regional Atmospheric Chemistry Experiment (BRACE), Florida, USA

    NASA Astrophysics Data System (ADS)

    Tremblay, Raphaël T.; Riemer, Daniel D.; Zika, Rod G.

    PM 2.5 and size-segregated aerosols were collected in May 2002 as part of the Bay Regional Atmospheric Chemistry Experiment (BRACE), Florida, USA. Aerosol organic composition was used to estimate sources of a series of alkanes and polycyclic aromatic hydrocarbons (PAHs) using chemical indices, hierarchical cluster analysis (HCA) and a chemical mass balance receptor model (CMB). Aerosols were collected on quartz fiber filters (QFF) using a PM 2.5 high volume sampler and on aluminum foil discs using a Micro-Orifice Uniform Deposit Impactor (MOUDI, 50% aerodynamic cut diameters were 18, 10, 5.6, 3.2, 1.8, 1.0, 0.56, 0.315 and 0.171 μm). Target compounds included alkanes and PAHs and were solvent extracted using a mixture of dichloromethane, acetone and hexane, concentrated and then analyzed using a gas chromatograph/mass spectrometer (GC/MS). The target compounds in PM 2.5 were dominated by six sources during the study period: mobile sources (39±5%), coal burning (33±5%), biogenic primary emission (20±2%), oil combustion (5±2%), biomass burning (1.0±0.3%) and an unidentified source (3±2%). Results obtained from the chemical indices, HCA and CMB were in very good agreement with each other. PAH size distributions are presented for days dominated by a same source. Seventy-five percent and 50% of the PAH were found below 1.8 and 0.56 μm, respectively (monthly PAH geometric diameters averaged 0.43 μm). Coarse size PAHs were observed on 1 day (15 May) and were correlated with nitrate and sodium size distribution. It is hypothesized that the PAHs, sodium and nitrate were internally mixed and that the PAHs deposited onto a pre-existing marine aerosol. This transfer process has significant implications for PAH deposition and lifetime and warrants further study.

  10. Water-soluble dicarboxylic acids and ω-oxocarboxylic acids in size-segregated aerosols over northern Japan during spring: sources and formation processes

    NASA Astrophysics Data System (ADS)

    Deshmukh, Dhananjay Kumar; Kawamura, Kimitaka; Kobayashi, Minoru; Gowda, Divyavani

    2016-04-01

    Seven sets (AF01-AF07) of size-segregated aerosol (12-sizes) samples were collected using a Micro-Orifice Uniform Deposit Impactor (MOUDI) in Sapporo, Japan during the spring of 2001 to understand the sources and atmospheric processes of water-soluble organic aerosols in the outflow region of Asian dusts. The samples were analyzed for dicarboxylic acids (C2-C12) and ω-oxocarboxylic acids as well as inorganic ions. The molecular distribution of diacids showed the predominance of oxalic acid (C2) followed by malonic and succinic acids whereas ω-oxoacids showed the predominance of glyoxylic acid (ωC2) in size-segregated aerosols. SO42- and NH4+ are enriched in submicron mode whereas NO3- and Ca2+ are in supermicron mode. Most of diacids and ω-oxoacids are enriched in supermicron mode in the samples (AF01-AF03) influenced by the long-range transport of mineral dusts whereas enhanced presence in submicron mode was observed in other sample sets. The strong correlations of C2 with Ca2+ (r = 0.95-0.99) and NO3- (r = 0.96-0.98) in supermicron mode in the samples AF01-AF03 suggest the adsorption or production of C2 diacid via heterogeneous reaction on the surface of mineral dust during long-range atmospheric transport. The preferential enrichment of diacids and ω-oxoacids in mineral dust has important implications for the solubility and cloud nucleation properties of the dominant fraction of water-soluble organic aerosols. This study demonstrates that biofuel and biomass burning and mineral dust originated in East Asia are two major factors to control the size distribution of diacids and related compounds over northern Japan.

  11. A concept of an automated function control for ambient aerosol measurements using mobility particle size spectrometers

    NASA Astrophysics Data System (ADS)

    Schladitz, A.; Merkel, M.; Bastian, S.; Birmili, W.; Weinhold, K.; Löschau, G.; Wiedensohler, A.

    2013-12-01

    An automated function control unit was developed to regularly check the ambient particle number concentration derived from a mobility particle size spectrometer as well as its zero-point behaviour. The aim of the new feature is to conduct unattended quality control experiments under field conditions at remote air quality monitoring or research stations. The automated function control also has the advantage of being able to get a faster system stability response than the recommended on-site comparisons with reference instruments. The method is based on a comparison of the total particle number concentration measured by a mobility particle size spectrometer and a condensation particle counter removing the diffusive particles approximately smaller than 25 nm in diameter. In practice, the small particles are removed by a set of diffusion screens, as traditionally used in a diffusion battery. The other feature of the automated function control is to check the zero-point behaviour of the ambient aerosol passing through a high-efficiency particulate air (HEPA) filter. An exemplary one-year data set is presented for the measurement site Annaberg-Buchholz as part of the Saxon air quality monitoring network. The total particle number concentration derived from the mobility particle size spectrometer overestimates the particle number concentration by only 2% (grand average offset). Furthermore, tolerance criteria are presented to judge the performance of the mobility particle size spectrometer with respect to the particle number concentration. An upgrade of a mobility particle size spectrometer with an automated function control enhances the quality of long-term particle number size distribution measurements. Quality assured measurements are a precondition for intercomparison studies of different sites. Comparable measurements will improve cohort health and also climate-relevant research studies.

  12. Detailed mass size distributions of elements and species, and aerosol chemical mass closure during fall 1999 at Gent, Belgium

    NASA Astrophysics Data System (ADS)

    Maenhaut, Willy; Cafmeyer, Jan; Dubtsov, Sergei; Chi, Xuguang

    2002-04-01

    A 10-stage microorifice uniform deposit impactor (MOUDI) and a 12-stage small deposit area low pressure impactor (SDI) were operated at Gent from 6 September to 30 October 1999. Thirty-four parallel samples (of typically 24 h) were collected. The MOUDI samples were analysed for the particulate mass (PM) by weighing, and for organic carbon (OC) and elemental carbon (EC) by a thermal-optical transmission technique. The SDI samples were analysed for 27 elements by PIXE. PM and OC exhibited typically a rather similar bimodal size distribution, with most of their mass in the submicrometer size range. EC was predominantly associated with fine particles, with maximum typically at around 0.2 μm equivalent aerodynamic diameter (EAD). Sulphur was also mainly in the fine size range, but with maximum at 0.5 μm EAD. Other elements with mainly a fine mode were V, Ni, As, Se and Pb. The crustal elements (Al, Si, Ti, Fe, Zr) exhibited mostly a unimodal coarse mode size distribution, with maximum at about 4 μm EAD. Other elements with mainly a coarse mode were Na, Mg, P, Ca, Cr, Mn, Cu, Ga and Sr. The elements K, Zn and Rb were generally bimodal. Aerosol chemical mass closure calculations indicated that organic aerosol and crustal matter were the major aerosol types in the supermicrometer size range, and that the dominant aerosol types in the submicrometer fraction were organic aerosol and sulphate. On average, 74% of the gravimetric PM was accounted for by the aerosol types considered.

  13. Modes in the size distributions and neutralization extent of fog-processed ammonium salt aerosols observed at Canadian rural locations

    NASA Astrophysics Data System (ADS)

    Yao, X. H.; Zhang, L.

    2012-02-01

    Among the 192 samples of size-segregated water-soluble inorganic ions collected using a Micro-Orifice Uniform Deposit Impactor (MOUDI) at eight rural locations in Canada, ten samples were identified to have gone through fog processing. The supermicron particle modes of ammonium salt aerosols were found to be the fingerprint of fog processed aerosols. However, the patterns and the sizes of the supermicron modes varied with ambient temperature (T) and particle acidity and also differed between inland and coastal locations. Under T > 0 °C condition, fog-processed ammonium salt aerosols were completely neutralized and had a dominant mode at 1-2 μm and a minor mode at 5-10 μm if particles were in neutral condition, and ammonium sulfate was incompletely neutralized and only had a 1-2 μm mode if particles were in acidic conditions. Under T < 0 °C at the coastal site, fog-processed aerosols exhibited a bi-modal size distribution with a dominant mode of incompletely-neutralized ammonium sulfate at about 3 μm and a minor mode of completely-neutralized ammonium sulfate at 8-9 μm. Under T < 0 °C condition at the inland sites, fog-processed ammonium salt aerosols were sometimes completely neutralized and sometimes incompletely neutralized, and the size of the supermicron mode was in the range from 1 to 5 μm. Overall, fog-processed ammonium salt aerosols under T < 0 °C condition were generally distributed at larger size (e.g., 2-5 μm) than those under T > 0 °C condition (e.g., 1-2 μm).

  14. Remote Sensing of Aerosol and Marine Parameters in Coastal Environments Using Polarized RT Simulations to Analyze OLCI Measurements

    NASA Astrophysics Data System (ADS)

    Stamnes, Knut; Stamnes, Snorre; Li, Wei; Fan, Yongzhen; Chen, Nan; Tanikawa, Tomo; Stamnes, Jakob J.

    2015-12-01

    A study was conducted to investigate whether imager-type spectroradiometer instruments like MODIS, currently flying on board the Aqua and Terra satellites, or MERIS, which flew on board Envisat, or OLCI, to be flown on board Sentinel 3, could detect absorbing aerosols if they could measure the Q Stokes parameter in addition to the total radiance I . Accurate radiative transfer calculations to produce synthetic data together with an optimal estimation inversion scheme was used to retrieve 3 aerosol parameters: aerosol optical depth, fraction of absorbing aerosols, and aerosol location. It was found that knowledge of I was generally insufficient to retrieve all 3 aerosol parameters, whereas knowledge of I and Q made it possible.

  15. Aerosol size-dependent below-cloud scavenging by rain and snow in the ECHAM5-HAM

    NASA Astrophysics Data System (ADS)

    Croft, B.; Lohmann, U.; Martin, R. V.; Stier, P.; Wurzler, S.; Feichter, J.; Posselt, R.; Ferrachat, S.

    2009-03-01

    Wet deposition processes are highly efficient in the removal of aerosols from the atmosphere, and thus strongly influence global aerosol concentrations, and clouds, and their respective radiative forcings. In this study, physically detailed size-dependent below-cloud scavenging parameterizations for rain and snow are implemented in the ECHAM5-HAM global aerosol-climate model. Previously, below-cloud scavenging by rain in the ECHAM5-HAM was simply a function of the aerosol mode, and then scaled by the rainfall rate. The below-cloud scavenging by snow was a function of the snowfall rate alone. The global mean aerosol optical depth, and sea salt burden are sensitive to the below-cloud scavenging coefficients, with reductions near to 15% when the more vigorous size-dependent below-cloud scavenging by rain and snow is implemented. The inclusion of a prognostic rain scheme significantly reduces the fractional importance of below-cloud scavenging since there is higher evaporation in the lower troposphere, increasing the global mean sea salt burden by almost 15%. Thermophoretic effects are shown to produce increases in the global and annual mean below-cloud number removal of Aitken size particles of near to 15%, but very small increases (near 1%) in the global mean below-cloud mass scavenging of carbonaceous and sulfate aerosols. Changes in the assumptions about the below-cloud scavenging of ultra-fine particles by rain do not cause any significant changes to the global mean aerosol mass or number burdens, despite a change in the below-cloud number removal rate for nucleation mode particles by near to 10%. For nucleation mode particles, changes to the assumptions about the below-cloud scavenging by snow produce a greater change in the number removal rate, in excess of one order of magnitude. Closer agreement with different observations is found when the more physically detailed below-cloud scavenging parameterization is employed in the ECHAM5-HAM model.

  16. Elucidating carbonaceous aerosol sources by the stable carbon δ13CTC ratio in size-segregated particles

    NASA Astrophysics Data System (ADS)

    Masalaite, A.; Remeikis, V.; Garbaras, A.; Dudoitis, V.; Ulevicius, V.; Ceburnis, D.

    2015-05-01

    Carbonaceous aerosol sources were investigated by measuring the stable carbon isotope ratio (δ13CTC) in size-segregated aerosol particles. The samples were collected with a micro-orifice uniform deposit impactor (MOUDI) in 11 size intervals ranging from 0.056 μm to 18 μm. The aerosol particle size distribution obtained from combined measurements with a scanning mobility particle sizer (SMPS; TSI 3936) and an aerosol particle sizer (APS; TSI 3321) is presented for comparison with MOUDI data. The analysis of δ13CTC values revealed that the total carbonaceous matter in size-segregated aerosol particles significantly varied from - 23.4 ± 0.1‰ in a coarse mode to - 30.1 ± 0.5‰ in a fine mode. A wide range of the δ13CTC values of size-segregated aerosol particles suggested various sources of aerosol particles contributing to carbonaceous particulate matter. Therefore, the source mixing equation was applied to verify the idea of mixing of two sources: continental non-fossil and fossil fuel combustion. The obtained δ13CTC value of aerosol particles originating from fossil fuel combustion was - 28.0 to - 28.1‰, while the non-fossil source δ13CTC value was in the range of - 25.0 to - 25.5‰. The two source mixing model applied to the size-segregated samples revealed that the fossil fuel combustion source contributed from 100% to 60% to the carbonaceous particulate matter in the fine mode range (Dp < 1 μm). Meanwhile, the second source, continental non-fossil, was the main contributor in the coarse fraction (Dp > 2 μm). The particle range from 0.5 to 2.0 μm was identified as a transition region where two sources almost equally contributed to carbonaceous particulate matter. The proposed mixing model offers an alternative method for determining major carbonaceous matter sources where radiocarbon analysis may lack the sensitivity (as in size-segregated samples).

  17. Size distributions and source function of sea spray aerosol over the South China Sea

    NASA Astrophysics Data System (ADS)

    Chu, Yingjia; Sheng, Lifang; Liu, Qian; Zhao, Dongliang; Jia, Nan; Kong, Yawen

    2016-08-01

    The number concentrations in the radius range of 0.06-5 μm of aerosol particles and meteorological parameters were measured on board during a cruise in the South China Sea from August 25 to October 12, 2012. Effective fluxes in the reference height of 10 m were estimated by steady state dry deposition method based on the observed data, and the influences of different air masses on flux were discussed in this paper. The number size distribution was characterized by a bimodal mode, with the average total number concentration of (1.50 ± 0.76)×103 cm-3. The two mode radii were 0.099 µm and 0.886 µm, both of which were within the scope of accumulation mode. A typical daily average size distribution was compared with that measured in the Bay of Bengal. In the whole radius range, the number concentrations were in agreement with each other; the modes were more distinct in this study than that abtained in the Bay of Bengal. The size distribution of the fluxes was fitted with the sum of log-normal and power-law distribution. The impact of different air masses was mainly on flux magnitude, rather than the shape of spectral distribution. A semiempirical source function that is applicable in the radius range of 0.06 µm< r 80<0.3 µm with the wind speed varying from 1.00 m s-1 to 10.00 m s-1 was derived.

  18. IN SITU MEASUREMENTS OF THE SIZE AND DENSITY OF TITAN AEROSOL ANALOGS

    SciTech Connect

    Hoerst, S. M.; Tolbert, M. A

    2013-06-10

    The organic haze produced from complex CH{sub 4}/N{sub 2} chemistry in the atmosphere of Titan plays an important role in processes that occur in the atmosphere and on its surface. The haze particles act as condensation nuclei and are therefore involved in Titan's methane hydrological cycle. They also may behave like sediment on Titan's surface and participate in both fluvial and aeolian processes. Models that seek to understand these processes require information about the physical properties of the particles including their size and density. Although measurements obtained by Cassini-Huygens have placed constraints on the size of the haze particles, their densities remain unknown. We have conducted a series of Titan atmosphere simulation experiments and measured the size, number density, and particle density of Titan aerosol analogs, or tholins, for CH{sub 4} concentrations from 0.01% to 10% using two different energy sources, spark discharge and UV. We find that the densities currently in use by many Titan models are higher than the measured densities of our tholins.

  19. Chemical composition of size-segregated aerosols in Lhasa city, Tibetan Plateau

    NASA Astrophysics Data System (ADS)

    Wan, Xin; Kang, Shichang; Xin, Jinyuan; Liu, Bin; Wen, Tianxue; Wang, Pengling; Wang, Yuesi; Cong, Zhiyuan

    2016-06-01

    To reveal the chemical characteristics of size-segregated aerosols in the high-altitude city of Tibetan Plateau, eight-size aerosol samples were collected in Lhasa from March 2013 to February 2014. The annual mean of online PM2.5 was 25.0 ± 16.0 μg m- 3, which was much lower than Asian cities but similar with some European cities. The annual mean concentrations of organic carbon (OC, 7.92 μg m- 3 in PM2.1 and 12.66 μg m- 3 in PM9.0) and elemental carbon (EC, 1.00 μg m- 3 in PM2.1 and 1.21 μg m- 3 in PM9.0) in Lhasa aerosols were considerably lower than those heavily polluted cities such as Beijing and Xi'an, China and Kathmandu, Nepal. Sulfate, NO3-, NH4+ and Ca2 + were 0.75 ± 0.31, 0.82 ± 0.35, 0.38 ± 0.34 and 0.57 ± 0.29 μg m- 3 in fine particles while in coarse particles they were 0.57 ± 0.37, 0.73 ± 0.23, 0.07 ± 0.03 and 2.52 ± 1.37 μg m- 3, respectively. Secondary water-soluble ions composed 35.8% of the total ionic components in fine particles according to the established electroneutrality, while in coarse particles they took up only 9.3%. Ca2 + (40.6%) was the major component of the coarse particles. For seasonality, the concentrations of OC, EC, SO42 -, NH4+, K+, Ca2 +, Mg2 +, Cl- and Na+ presented higher values during late autumn and winter but were relatively lower in spring and summer. Nevertheless, NO3- was considerably higher in summer and autumn, presumably due to increased tourist-vehicle emissions. During winter and spring, [Ca2 +]/[NO3-+ SO42 -] ratios in coarse particles showed higher values of 7.31 and 6.17, respectively, emphasizing the dust influence. [NO3-]/[SO42 -] ratios in fine particles during spring, summer and autumn exceeding 1 indicated that the currently predominant vehicle exhaust makes a greater contribution to the aerosols. While more stationary sources such as coal and biomass burning existed in winter since the [NO3-]/[SO42 -] ratio was less than 1. Different sources and formation processes lead to a bimodal size

  20. Size Distributions and Formation Pathways of Organic and Inorganic Constituents in Spring Aerosols from Okinawa Island in the Western North Pacific Rim: An Outflow Region of Asian Dusts

    NASA Astrophysics Data System (ADS)

    Deshmukh, D. K.; Lazaar, M.; Kawamura, K.; Kunwar, B.; Tachibana, E.; Boreddy, S. K. R.

    2015-12-01

    Size-segregated aerosols (9-stages) were collected at Okinawa Island in the western North Pacific Rim in spring 2008. The samples were analyzed for diacids (C2-C12), ω-oxoacids (ωC2-ωC9), a-dicarbonyls (C2-C3), organic carbon (OC), water-soluble OC (WSOC) and major ions to understand the sources and atmospheric processes in the outflow region of Asian pollutants. The molecular distribution of diacids showed the predominance of oxalic acid (C2) followed by malonic and succinic acids in all the size-segregated aerosols. ω-Oxoacids showed the predominance of glyoxylic acid (ωC2) whereas glyoxal (Gly) was more abundant than methylglyoxal in all the sizes. The abundant presence of sulfate as well as phthalic and adipic acids in Okinawa aerosols suggested a significant contribution of anthropogenic sources in East Asia via long-range atmospheric transport. Diacids (C2-C5), ωC2 and Gly as well as WSOC and OC peaked at 0.65-1.1 µm in fine mode whereas azelaic (C9) and 9-oxononanoic (ωC9) acids peaked at 3.3-4.7 µm in coarse mode. Sulfate and ammonium are enriched in fine mode whereas sodium and chloride are in coarse mode. An important mechanism for the formation of these organic species in Okinawa aerosols is probably gas phase oxidation of VOCs and subsequent in-cloud processing during long-range transport. Their characteristics size distribution implies that fine particles enriched with these organic and inorganic species could act as CCN to develop the cloud cover over the western North Pacific. The major peak of C9 and ωC9 on coarse mode suggest that they are produced by photooxidation of unsaturated fatty acids mainly derived from phytoplankton via heterogeneous reactions on sea spray particles. This study demonstrates that anthropogenic aerosols emitted from East Asia have significant influence on the compositions of organic and inorganic aerosols in the western North Pacific Rim.

  1. Finite-size effects on long-range correlations: implications for analyzing DNA sequences

    NASA Technical Reports Server (NTRS)

    Buldyrev, S. V.; Goldberger, A. L.; Havlin, S.; Simons, M.; Stanley, H. E.

    1993-01-01

    We analyze the fluctuations in the correlation exponents obtained for noncoding DNA sequences. We find prominent sample-to-sample variations as well as variations within a single sample in the scaling exponent. To determine if these fluctuations may result from finite system size, we generate correlated random sequences of comparable length and study the fluctuations in this control system. We find that the DNA exponent fluctuations are consistent with those obtained from the control sequences having long-range power-law correlations. Finally, we compare our exponents for the DNA sequences with the exponents obtained from power-spectrum analysis and correlation-function techniques, and demonstrate that the original "DNA-walk" method is intrinsically more accurate due to reduced noise.

  2. Automated Measurements of Ambient Aerosol Chemical Composition and its Dry and Wet Size Distributions at Pittsburgh Supersite

    NASA Astrophysics Data System (ADS)

    Khlystov, A. Y.; Stanier, C.; Chun, W.; Vayenas, D.; Mandiro, M.; Pandis, S. N.

    2001-12-01

    Ambient aerosol particles change size with changes in ambient relative humidity. The magnitude of the size change depends on the hygroscopic properties of the particles, which is determined by their chemical composition. Hygroscopic properties of particles influence many environmentally important aerosol qualities, such as light scattering and partitioning between the gas and particle phases of semivolitile compounds. Studying the hygroscopic growth of ambient particles is thus of paramount importance. The highroscopic growth of ambient particles and their chemical composition are measured continuously within the Pittsburgh Air Quality Study (EPA supersite program). The hygroscopic size changes are measured using an automated system built for this study. The system consists of two Scanning Mobility Particle Sizers (SMPS, TSI Inc.) and an Aerodynamic Particle Sizer (APS, TSI Inc.). The three instruments measure aerosol size distribution between 5 nanometers and 10 micrometers in diameter. The inlets of the instruments and the sheath air lines of the SMPS systems are equipped with computer controlled valves that direct air through Nafion dryers (PermaPure Inc.) or bypass them. The Nafion dryers are drying the air stream below 40% RH at which point ambient particles are expected to lose most or all water and thus be virtually dry. To avoid changes in relative humidity and evaporation of volatile particles due to temperature differences the system is kept at ambient temperature. The system measures alternatively dry (below 40% RH) and wet (actual ambient RH) aerosol size distributions every 6 minutes. The hygroscopic growth observed with the size-spectrometer system is compared with theoretic predictions based on the chemical composition of aerosol particles. A modified semi-continuous Steam-Jet Aerosol Collector provides the total available budget (particles and gas) of water-soluble species, which is used as an input to the thermodynamic model. The model calculates

  3. A concept of an automated function control for ambient aerosol measurements using mobility particle size spectrometers

    NASA Astrophysics Data System (ADS)

    Bastian, S.; Löschau, G.; Wiedensohler, A.

    2014-04-01

    An automated function control unit was developed to regularly check the ambient particle number concentration derived from a mobility particle size spectrometer as well as its zero-point behaviour. The function control allows unattended quality assurance experiments at remote air quality monitoring or research stations under field conditions. The automated function control also has the advantage of being able to get a faster system stability response than the recommended on-site comparisons with reference instruments. The method is based on a comparison of the total particle number concentration measured by a mobility particle size spectrometer and a condensation particle counter while removing diffusive particles smaller than 20 nm in diameter. In practice, the small particles are removed by a set of diffusion screens, as traditionally used in a diffusion battery. Another feature of the automated function control is to check the zero-point behaviour of the ambient aerosol passing through a high-efficiency particulate air (HEPA) filter. The performance of the function control is illustrated with the aid of a 1-year data set recorded at Annaberg-Buchholz, a station in the Saxon air quality monitoring network. During the period of concern, the total particle number concentration derived from the mobility particle size spectrometer slightly overestimated the particle number concentration recorded by the condensation particle counter by 2 % (grand average). Based on our first year of experience with the function control, we developed tolerance criteria that allow a performance evaluation of a tested mobility particle size spectrometer with respect to the total particle number concentration. We conclude that the automated function control enhances the quality and reliability of unattended long-term particle number size distribution measurements. This will have beneficial effects for intercomparison studies involving different measurement sites, and help provide a higher

  4. Dicarboxylic acids, ω-oxocarboxylic acids, α-dicarbonyls, WSOC, OC, EC, and inorganic ions in wintertime size-segregated aerosols from central India: Sources and formation processes.

    PubMed

    Deshmukh, Dhananjay K; Kawamura, Kimitaka; Deb, Manas K

    2016-10-01

    The size distributions of aerosols can provide evidences for their sources and formation processes in the atmosphere. Size-segregated aerosols (9-sizes) were collected in urban site (Raipur: 21.2°N and 82.3°E) in central India during winter of 2012-2013. The samples were analyzed for dicarboxylic acids (C2-C12), ω-oxocarboxylic acids (ωC2-ωC9), pyruvic acid and α-dicarbonyls (C2-C3) as well as elemental carbon (EC), organic carbon (OC), water-soluble OC (WSOC) and inorganic ions. Diacids showed a predominance of oxalic acid (C2) followed by succinic and azelaic acid whereas ω-oxoacids exhibited a predominance of glyoxylic acid and glyoxal was more abundant than methylglyoxal in all the sizes. Diacids, ω-oxoacids and α-dicarbonyls showed bimodal size distribution with peaks in fine and coarse modes. High correlations of fine mode diacids and related compounds with potassium and levoglucosan suggest that they were presumably due to a substantial contribution of primary emission from biomass burning and secondary production from biomass burning derived precursors. High correlations of C2 with higher carbon number diacids (C3-C9) suggest that they have similar sources and C2 may be produced via the decay of its higher homologous diacids in fine mode. Considerable portions of diacids and related compounds in coarse mode suggest that they were associated with mineral dust particles by their adsorption and photooxidation of anthropogenic and biogenic precursors via heterogeneous reaction on dust surface. This study demonstrates that biomass burning and dust particles are two major factors to control the size distribution of diacids and related compounds in the urban aerosols from central India. PMID:27414241

  5. Effects of diesel exhaust aftertreatment devices on concentrations and size distribution of aerosols in underground mine air.

    PubMed

    Bugarski, Aleksandar D; Schnakenberg, George H; Hummer, Ion A; Cauda, Emanuele; Janisko, Samuel I; Patts, Larry D

    2009-09-01

    Three types of uncatalyzed diesel particulate filter (DPF) systems, three types of high-temperature disposable filter elements (DFEs), and one diesel oxidation catalytic converter (DOC) were evaluated in underground mine conditions for their effects on the concentrations and size distributions of diesel aerosols. Those effects were compared with the effects of a standard muffler. The experimental work was conducted directly in an underground environment using a unique diesel laboratory developed in an underground experimental mine. The DPF systems reduced total mass of aerosols in the mine air approximately 10-fold for light-load and 20-fold or more for high-load test conditions. The DFEs offered similar reductions in aerosol mass concentrations. The efficiency of the new DFEs significantly increased with accumulation of operating time and buildup of diesel particulate matter in the porous structure of the filter elements. A single laundering process did not exhibit substantial effects on performance of the filter element The effectiveness of DPFs and DFEs in removing aerosols by number was strongly influenced by engine operating mode. The concentrations of nucleation mode aerosols in the mine air were found to be substantially higher for both DPFs and DFEs when the engine was operated at high-load modes than at low-load modes. The effects of the DOC on mass and number concentrations of aerosols in mine air were relatively minor when compared to those of the DPF and DFE systems. PMID:19764243

  6. Using Kinect to analyze pebble to block-sized clasts in sedimentology

    NASA Astrophysics Data System (ADS)

    Moreno Chávez, G.; Sarocchi, D.; Arce Santana, E.; Borselli, L.; Rodríguez-Sedano, L. A.

    2014-11-01

    In this paper, we propose a new system for automatically measuring grain sizes in a range from pebbles to blocks. The system is based on use of the Microsoft Kinect device and a novel software developed by the authors which enables a tridimensional digital model of a selected area of an outcrop to be captured. With the tridimensional model, clasts are stacked using new segmentation algorithms based on level sets and Fourier analysis. The resulting binary image (clasts and matrix) is analyzed by means of the Rosiwal stereological method. The granulometric Cumulative Distribution Function (CDF), obtained automatically by this new methodology, was compared to the granulometric CDF, obtained manually by the Rosiwal technique, by means of a Kolmogorov-Smirnov test. The comparison showed good agreement between the methods and demonstrated that this inexpensive system (already used in several scientific fields) with great potential can also be used to obtain fast, automatic and accurate grain size distributions of sedimentary deposits. The software tools used to control the Kinect device, which provide the three-dimensional elevation models of the outcrops and allows its analysis, are freely available from the author.

  7. Current Development Status of a Particle Size Analyzer for Coated Particle Fuel

    SciTech Connect

    Nelson, Andrew T; Hunn, John D; Karnowski, Thomas Paul

    2007-08-01

    Work was performed to develop a prototype Particle Size Analyzer (PSA) for application to coated particle fuel characterization. This system was based on a light obscuration method and targeted towards high throughput analysis. Although never matured to the point of replacing existing lower throughput optical microscopy shadowgraph methods, the system was successfully applied to automating the counting of large particle samples for increased accuracy in calculating mean particle properties based on measurements of multiparticle samples. The measurement of particle size with the PSA was compared to current shadowgraph techniques and found to result in considerably greater throughput at the cost of larger measurement uncertainty. The current algorithm used by the PSA is more sensitive to particle shape and this is a likely cause of the greater uncertainty when attempting to measure average particle diameter. The use of the PSA to measure particle shape will require further development. Particle transport through the PSA and stability of the light source/detector are key elements in the successful application of this technique. A number of system pitfalls were studied and addressed.

  8. Measurements of the Aerosol Size Distribution Down to 1 Nanometer to Investigate Aerosol Nucleation and Initial Growth During the GoAmazon Campaign

    NASA Astrophysics Data System (ADS)

    Kuang, C.; Artaxo, P.; Backman, J.; Kim, S.; Kulmala, M. T.; Martin, S. T.; Petäjä, T.; Seco, R.; Smith, J. N.; Souza, R. A. F. D.

    2014-12-01

    Atmospheric particle nucleation is an important environmental nano-scale process, with field measurements and modeling studies indicating that freshly nucleated particles are a significant source of global cloud condensation nuclei. However, our understanding of atmospheric nucleation and its influence on climate is limited as few ambient measurements have been made of either the nucleation rate (at 1 nm) or the initial growth rate of newly formed clusters (from 1 to 3 nm), both of which are necessary to constrain and investigate the nucleation mechanism and to develop process-level models. Aerosol nucleation and initial growth were investigated during the Green Ocean Amazon (GoAmazon) campaign spanning the wet and dry seasons of 2014 downwind of the city of Manaus, Brazil. Aerosol measurement was accomplished through the deployment of a condensation particle counter-based electrical mobility spectrometer, optimized for the detection of aerosol down to 1 nm in diameter. An electrometer-based neutral air ion spectrometer was also deployed at the same location to measure the neutral and charged fraction of aerosol down to 1.5 nm in diameter. From these size distribution measurements, periods of nucleation will be identified, and the resulting nucleation rates and initial growth rates will be presented. Concurrent and co-located measurements of gas-phase sulfuric acid will provide the opportunity to investigate the functional contribution of sulfuric acid to the observed nucleation rate and initial growth rate.

  9. Determination of isoprene-derived secondary organic aerosol tracers (2-methyltetrols) by HPAEC-PAD: Results from size-resolved aerosols in a tropical rainforest

    NASA Astrophysics Data System (ADS)

    Zhang, Zhi-Sheng; Engling, Guenter; Chan, Chuen-Yu; Yang, Yi-Hong; Lin, Mang; Shi, Si; He, Jun; Li, Yi-De; Wang, Xue-Mei

    2013-05-01

    Secondary organic aerosol (SOA) formed from oxidation of isoprene, the most abundant nonmethane hydrocarbon in the atmosphere, has been estimated to contribute significantly to the global aerosol burden. Measurement of isoprene-derived SOA molecular markers has become an effective method for the investigation of biogenic aerosol contributions in the atmosphere. The primary goals of this work are to present a new method based on high-performance anion exchange chromatography with pulsed amperometric detection (HPAEC-PAD) to quantify diastereoisomeric 2-methyltetrols (2-methylerythritol and 2-methylthreitol), marker compounds of isoprene-derived SOA, and thus to obtain better understanding regarding their abundance and size distribution specifically in a rainforest area. The 2-methyltetrol data, along with water-soluble inorganic ion concentrations, were obtained from size-segregated samples collected at a tropical rainforest site in South China during the period from May to June, 2010. The concentrations of 2-methyltetrols from selected samples measured by HPAEC-PAD showed good agreement with those measured by GC/MS. Overall, the HPAEC-PAD method provides a simple and fast, yet selective and sensitive, alternative to GC/MS for 2-methyltetrol determination, allowing for more efficient analysis of large sample numbers. The size distributions of 2-methylerythritol and 2-methylthreitol both exhibited a unimodal pattern, peaking in the particle size range of 0.44-1.0 μm, where their average concentrations were 11.7 and 4.2 ng m-3, respectively. A strong correlation between 2-methylerythritol and 2-methylthreitol was observed among the entire set of size-segregated samples, indicating their photochemical origin and similar formation mechanism regardless of particle sizes. Compared to the results obtained from previous chamber studies, the similar isomeric fraction of 2-methyltetrols obtained in this study and other field studies confirms their formation through

  10. Hygroscopic growth of size-resolved, emission-source classified, aerosol particles sampled across the United States

    NASA Astrophysics Data System (ADS)

    Shingler, T.; Crosbie, E. C.; Ziemba, L. D.; Anderson, B. E.; Campuzano Jost, P.; Jimenez, J. L.; Mikoviny, T.; Wisthaler, A.; Sorooshian, A.

    2014-12-01

    The hygroscopic growth of atmospheric aerosol particles is a key air quality parameter, impacting the radiation budget, visibility, and cloud formation. During the DC3 and SEAC4RS field campaigns (>300 total flight hours), measurements were made over 32 US states, Canada, the Pacific Ocean, and the Gulf of Mexico, between the surface and 41,000 feet ASL. The aircraft research payloads included a suite of in-situ aerosol and gas phase instruments. The Differential Aerosol Sizing and Hygroscopicity Spectrometer Probe (DASH-SP) and the Langley Aerosol Research Group Experiment (LARGE) humidified nephelometer instrument applied different techniques to measure water uptake by aerosol particles at prescribed relative humidity values. Size-resolved growth factor (GF ≡ Dp,wet/Dp,dry) measurements by the DASH-SP are compared to bulk scattering measurements (f(RH) ≡ σscat,wet/σscat,dry) by the LARGE instrument. Spatial location and volatile organic compound tracers such as isoprene and acetonitrile are used to classify the origin of distinct air masses, including: forest fires, biogenic-emitting forests, agricultural use lands, marine boundary layer, urban, and rural background. Analyses of GF results by air mass origin are reported and results are compared with f(RH) measurements. A parameterization between the f(RH) and GF measurements and its potential uses are discussed.

  11. High-solids paint overspray aerosols in a spray painting booth: particle size analysis and scrubber efficiency

    SciTech Connect

    Chan, T.L.; D'arcy, J.B.; Schreck, R.M.

    1986-07-01

    Particle size distributions of high-solids acrylic-enamel paint overspray aerosols were determined isokinetically in a typical downdraft spray painting booth in which a 7-stage cascade impactor was used. Three different industrial paint atomizers were used, and the paint aerosols were characterized before and after a paint both scrubber. The mass median aerodynamic diameter (MMAD) of a metallic basecoat and an acrylic clearcoat paint aerosol from air-atomized spray guns ranged from 4-12 ..mu..m and was dependent on atomization pressure. When the paint booth was operated under controlled conditions simulating those in a plant, the collection efficiency of paint overspray aerosols by a paint scrubber was found to be size dependent and decreased sharply for particles smaller than 2 ..mu..m to as low as 64% for clearcoat paint particles of 0.6 ..mu..m. Improvement in the overall particulate removal efficiency can be achieved by optimizing the spray painting operations so as to produce the least amount of fine overspray paint aerosols less than 2 ..mu..m. Maintaining a higher static pressure drop across the paint both scrubber also will improve scrubber performance.

  12. Analysis of the atmospheric aerosol size distribution information retrievable from near-limb angular radiance measurements taken on Mauna Loa, Hawaii

    SciTech Connect

    Grant, K.E.

    1981-12-01

    Angular radiance measurements of the near-limb solar aureole were analyzed for information regarding the light-scattering aerosol particles in the atmospheric column above Mauna Loa, Hawaii. The Mauna Loa Observatory, located at 19/sup 0/ 33' N latitude, 155/sup 0/ 35' W longitude, and 3460 metres elevation, is in unpolluted air above the easterly trade wind inversion and has been designated as a site for the Geophysical Monitoring for Climatic Change (GMCC) program. Circumsolar radiance and polarization measurements have been collected on Mauna Loa since 1963 by the High Altitude Observatory (HAO), National Center for Atmospheric Research (NCAR) as part of a program for the daily observation of the solar corona. Strip charts containing radiance measurements made from January 1976 through June 1978 were made available for this study. By the use of Mie scattering theory, generalized to treat the sun as a finite diameter light source with limb-darkening, a theoretical scattering matrix was calculated for observation angles between 17' and 300' measured from the center of the solar disk, and aerosol size parameters (2..pi..r/lambda) between 10 and 300. An information content criterion is presented, based on the expected relative norm of the measurement errors and on the eigenvalues of the radiance covariance matrix of the scattering matrix. The observed aureole radiance gradients and two test gradients were inverted to obtain aerosol size distributions using a constrained linear inversion algorithm.

  13. Characteristics of aerosol size distributions and chemical compositions during wintertime pollution episodes in Beijing

    NASA Astrophysics Data System (ADS)

    Liu, Zirui; Hu, Bo; Zhang, Junke; Yu, Yangchun; Wang, Yuesi

    2016-02-01

    To characterize the features of particle pollution, continuous measurements of particle number size distributions and chemical compositions were performed at an urban site in Beijing in January 2013. The particle number and volume concentration from 14 nm to 1000 nm were (37.4 ± 15.3) × 103 cm- 3 and (85.2 ± 65.6) μm3 cm- 3, respectively. N-Ait (Aitken mode) particles dominated the number concentration, whereas N-Acc (accumulation mode) particles dominated the volume concentration. Submicron particles were generally characterized by a high content of organics and SO42 -, and a low level of NO3- and Cl-. Two types of pollution episodes were observed, characterized by the "explosive growth" (EXP) and "sustained growth" (SUS) of PM2.5. Fine particles greater than 100 nm dominated the volume concentration during the ends of these pollution episodes, shifting the maximum of the number size distribution from 60 nm to greater than 100 nm in a few hours (EXP) or a few days (SUS). Secondary transformation is the main reason for the pollution episodes; SO42 -, NO3- and NH4+ (SNA) accounted for approximately 42% (EXP) and greater than 60% (SUS) of the N-Acc particle mass increase. The size distributions of particulate organics and SNA varied on timescales of hours to days, the characteristics of which changed from bimodal to unimodal during the evolution of haze episodes. The accumulation mode (peaking at approximately 500-700 nm) was dominated by organics that appeared to be internally mixed with nitrate or sulfate. The sulfate was most likely formed via heterogeneous reactions, because the SOR was constant under dry conditions (RH < 50%) and began to increase when RH > 50%, suggesting an important contribution from heterogeneous reactions with abundant aerosol water under wet conditions. Finally, the correlations between [NO3-]/[SO42 -] and [NH4+]/[SO42 -] suggest that the homogenous reaction between HNO3 and NH3 dominated the formation of nitrate under conditions of

  14. Aerosol Particle Size Retrievals from the Compact Reconnaissance Imaging Spectrometer for Mars

    NASA Astrophysics Data System (ADS)

    Guzewich, S.; Smith, M. D.; Wolff, M. J.

    2013-12-01

    During the extended mission of the Mars Reconnaisance Orbiter, the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) has made periodic limb-viewing geometry observations of the Martian atmosphere. Sufficient radiance is typically available to produce a vertical distribution of dust and water ice aerosols from the surface to approximately 50 km altitude. Radiative transfer modeling is conducted to achieve a best fit between the observed and modeled spectrum. The spherical geometry of the limb-viewing geometry is handled using a pseudo-spherical approximation that is computationally efficient and accurate to within a few percent of a Monte Carlo method for the geometries observed. Different particle sizes of dust and water ice have unique extinction coefficients across the visible and near-infrared portion of the spectrum observed by CRISM. We use a wide range of wavelengths across the CRISM spectrum to conduct the retrieval. Here we provide initial results on the retrieval of dust and water ice particle sizes over the duration of the CRISM limb-viewing observations.

  15. Chamber bioaerosol study: human emissions of size-resolved fluorescent biological aerosol particles.

    PubMed

    Bhangar, S; Adams, R I; Pasut, W; Huffman, J A; Arens, E A; Taylor, J W; Bruns, T D; Nazaroff, W W

    2016-04-01

    Humans are a prominent source of airborne biological particles in occupied indoor spaces, but few studies have quantified human bioaerosol emissions. The chamber investigation reported here employs a fluorescence-based technique to evaluate bioaerosols with high temporal and particle size resolution. In a 75-m(3) chamber, occupant emission rates of coarse (2.5-10 μm) fluorescent biological aerosol particles (FBAPs) under seated, simulated office-work conditions averaged 0.9 ± 0.3 million particles per person-h. Walking was associated with a 5-6× increase in the emission rate. During both walking and sitting, 60-70% or more of emissions originated from the floor. The increase in emissions during walking (vs. while sitting) was mainly attributable to release of particles from the floor; the associated increased vigor of upper body movements also contributed. Clothing, or its frictional interaction with human skin, was demonstrated to be a source of coarse particles, and especially of the highly fluorescent fraction. Emission rates of FBAPs previously reported for lecture classes were well bounded by the experimental results obtained in this chamber study. In both settings, the size distribution of occupant FBAP emissions had a dominant mode in the 3-5 μm diameter range. PMID:25704637

  16. Influence of flow rate on aerosol particle size distributions from pressurized and breath-actuated inhalers.

    PubMed

    Smith, K J; Chan, H K; Brown, K F

    1998-01-01

    Particle size distribution of delivered aerosols and the total mass of drug delivered from the inhaler are important determinants of pulmonary deposition and response to inhalation therapy. Inhalation flow rate may vary between patients and from dose to dose. The Andersen Sampler (AS) cascade impactor operated at flow rates of 30 and 55 L/min and the Marple-Miller Impactor (MMI) operated at flow rates of 30, 55, and 80 L/min were used in this study to investigate the influence of airflow rate on the particle size distributions of inhalation products. Total mass of drug delivered from the inhaler, fine particle mass, fine particle fraction, percentage of nonrespirable particles, and amount of formulation retained within the inhaler were determined by ultraviolet spectrophotometry for several commercial bronchodilator products purchased in the marketplace, including a pressurized metered-dose inhaler (pMDI), breath-actuated pressurized inhaler (BAMDI), and three dry powder inhalers (DPIs), two containing salbutamol sulphate and the other containing terbutaline sulphate. Varying the flow rate through the cascade impactor produced no significant change in performance of the pressurized inhalers. Increasing the flow rate produced a greater mass of drug delivered and an increase in respirable particle mass and fraction from all DPIs tested. PMID:10346666

  17. Analyzing the Effect of Intraseasonal Meteorological Variability and Land Cover on Aerosol-Cloud Interactions During the Amazonian Biomass Burning Season

    NASA Technical Reports Server (NTRS)

    TenHoeve, J. E.; Remer, L. A.; Jacobson, M. Z.

    2010-01-01

    High resolution aerosol, cloud, water vapor, and atmospheric profile data from the Moderate Resolution Imaging Spectroradiometer (MODIS) are utilized to examine the impact of aerosols on clouds during the Amazonian biomass burning season in Rondnia, Brazil. It is found that increasing background column water vapor (CWV) throughout this transition season between the Amazon dry and wet seasons exerts a strong effect on cloud properties. As a result, aerosol-cloud correlations should be stratified by column water vapor to achieve a more accurate assessment of the effect of aerosols on clouds. Previous studies ignored the systematic changes to meteorological factors during the transition season, leading to possible misinterpretation of their results. Cloud fraction is shown generally to increase with aerosol optical depth (AOD) for both low and high values of column water vapor, whereas the relationship between cloud optical depth (COD) and AOD exhibits a different relationship. COD increases with AOD until AOD approx. 0.25 due to the first indirect (microphysical) effect. At higher values of AOD, COD is found to decrease with increasing AOD, which may be due to: (1) the inhibition of cloud development by absorbing aerosols (radiative effect) and/or (2) a retrieval artifact in which the measured reflectance in the visible is less than expected from a cloud top either from the darkening of clouds through the addition of carbonaceous biomass burning aerosols or subpixel dark surface contamination in the measured cloud reflectance. If (1) is a contributing mechanism, as we suspect, then a linear relationship between the indirect effect and increasing AOD, assumed in a majority of GCMs, is inaccurate since these models do not include treatment of aerosol absorption in and around clouds. The effect of aerosols on both column water vapor and clouds over varying land surface types is also analyzed. The study finds that the difference in column water vapor between forest and

  18. Chemical Composition, Seasonal Variation and Size distribution of Atmospheric Aerosols at an Alpine Site in Guanzhong Plain, China

    NASA Astrophysics Data System (ADS)

    Li, J.

    2015-12-01

    PM10 and size-segregated aerosol samples were collected at Mt. Hua (2065 a.s.m) in central China, and determined for carbonaceous fraction, ions and organic composition. The concentration of most chemical compositions in summer are lower than those in winter, due to decreased emissions of biomass and coal burning for house heating. High temperature and relative humidity (RH) conditions are favorable for secondary aerosol formation, resulting in higher concentrations of SO42- and NH4+ in summer. Non-dehydrated sugars are increased in summer because of the enhanced metabolism. Carbon preference index results indicate that n-alkanes at Mt. Hua are derived mostly by plant wax. Low Benzo(a)pyrene/Benzo(a)pyrene ratios indicate that mountain aerosols are more aged. Concentrations of biogenic (BSOA, the isoprene/pinene/caryophyllene oxidation products) and anthropogenic (ASOA, mainly aromatic acids) SOA positively correlated with temperature . However, a decreasing trend of BSOA concentration with an increase in RH was observed during the sampling period, although a clear trend between ASOA and RH was not found. Based on the AIM Model calculation, we found that during the sampling period an increase in RH resulted in a decrease in the aerosol acidity and thus reduced the effect of acid-catalysis on BSOA formation. Size distributions of K+ and NH4+ present as an accumulation mode, in contrast to Ca2+ and Mg2+, which are mainly existed in coarse particles. SO42- and NO3- show a bimodal pattern. Dehydrated sugars, fossil fuel derived n-alkanes and PAHs presented unimode size distribution, whereas non-dehydrated sugars and plant wax derived n-alkanes showed bimodal pattern. Most of the determined BSOA are formed in the aerosol phase and enriched in the fine mode except for cis-pinonic acid, which is formed in the gas phase and subsequently partitioned into aerosol phase and thus presents a bimodal pattern with a major peak in the coarse mode.

  19. Use of atmospheric elemental size distributions in estimating aerosol sources in the Helsinki area

    NASA Astrophysics Data System (ADS)

    Pakkanen, Tuomo A.; Kerminen, Veli-Matti; Korhonen, Christina H.; Hillamo, Risto E.; Aarnio, Päivi; Koskentalo, Tarja; Maenhaut, Willy

    In June 1996-June 1997 Berner impactors were used in the Helsinki area to measure size distributions of atmospheric aerosols simultaneously at an urban and at a rural site. Ten sample pairs were collected in the size range of 0.03-15.7 μm of equivalent aerodynamic diameter (EAD). Average size distributions at the two sites were calculated for 29 elements, particulate mass, and sulphate. At both sites especially sulphate, As, B, Bi, Cd, Ni, Tl, and V were enriched in fine particles (EAD<2.3 μm). In order to estimate local fine-particle sources of the various chemical components, the similarities and dissimilarities in the accumulation-mode parameters were studied separately for both sites. It was observed that often in different samples, different components had similar accumulation modes. At both sites, particulate mass, As, and Pb had similar accumulation modes to sulphate which suggests that long-range transport (LRT) is important for these components. V, Ni, Mo, and Co formed another group of similar accumulation modes at both sites suggesting that these elements largely originated from local and regional oil combustion. In addition, other groups of similar accumulation modes were observed but these groups were different between the sites. The meteorological parameters indicated that seven sample pairs formed a subset of the data in which the local emissions of the Helsinki area were transported to the urban site but not to the rural site. For this subset the rural fine-particle concentrations were considered to represent an upper limit estimate for the LRT. These upper limit LRT estimations were further improved by utilising the quantitative relative size distributions (QRSD) method at the rural site. The QRSD method supposes that in the fine-particle size range the LRT fractions of all chemical components have a similar shape in their size distributions. Fine-particle sulphate is typically long-range transported, and was therefore selected as the model

  20. Aerosol/cloud Base Droplet Size Distribution Characteristics and the Onset of Coalescence in Shallow and Deep Convective Clouds

    NASA Astrophysics Data System (ADS)

    Bruintjes, R. T.; Lawson, P.; Lance, S.; Axisa, D.; Woods, S.

    2014-12-01

    It is clear that aerosols contribute to the observed differences in cloud droplet size distributions between maritime and continental and between non-polluted and polluted convection. In addition, other factors such as cloud base temperature, boundary layer depth, thermodynamic profile (updraft speeds) that vary between land and ocean regions, could also be contributing to the observed differences or acting in concert with aerosol effects. In addition, the initial cloud droplet spectra at cloud base to a large extent determines the microphysical processes of precipitation formation (water and ice) at higher levels in the clouds and thus the vertical transport of aerosols and gases in deep convective clouds. During the 2013 NASA SEAC4RS field campaign we have collected a large amount of microphysical data in both shallow and deep convective clouds. This data will be compared to data from other field campaigns to detect specific characteristics of the cloud base droplet size distribution and relate it to onset and evolution of the coalescence process in clouds. The presentation will provide a survey of the cloud droplet size distributions at cloud base in both shallow and deep convective clouds and will relate them to environmental parameters to better understand aerosol-cloud interactions and the other parameters that play a role in the onset of coalescence in convective clouds. We will relate the airborne aerosol variations (size and concentration in different environments) to the cloud droplet size distribution. Model simulations using a detailed coalescence model will be used to obtain a better understanding of the onset of the coalescence process.

  1. Particle Size Distributions of Water Soluble Species and Nutrient Elements in Aerosols over the Southern Ocean and Coastal East Antarctica

    NASA Astrophysics Data System (ADS)

    Xu, G.; Gao, Y.

    2012-12-01

    The particle size is an important parameter to determin the chemical and physical properties of aerosols of marine origin, especially the fine mode particles that may act as cloud condenstation neuclei (CCN), affecting cloud microphysics and consequently climate. The air-to-sea deposition of aerosol particles are also dependent on particle sizes, which are important for the calculation of atmospheric nutrient fluxes to the ocean. To characterize the size distributions of water-soluble inorganic, organic aerosol species (including Na+, non-sea-salt (nss) sulfate, methane sulfonate (MSA), oxalate and succinate) of marine origin and nutrient elements (inlcuding Cu, Fe, Mn, Ni and Zn and Cd) over the Southern Ocean and coastal East Antarctica, size-segregated aerosols were collected from 40°S, 100°E to 69°S, 76°E and between 69°S, 76°E and 66°S, 110°E during a cruise from November 2010 to March 2011. Results indicate that sea salt particles, a major aerosol component and generated by strong westerly winds, existed mainly in the coarse mode with a concentration peak at >3.0 μm over the Southern Ocean. However, the nss-sulfate, a secondary aerosol species, existed mainly in the fine mode, with a single peak at <0.49 μm over the Southern Ocean, and in a bimodal distribution, peaking at 0.10 - 0.18 μm and 0.32 - 0.56 μm over coastal East Antarctic seas. Over the Southern Ocean, MSA showed a bimodal distribution, a large peak at 0.32-0.56 μm and a small peak at 3.0-7.2 μm, while over coastal East Antarctica, MSA was enriched in particles of 0.32-0.56 μm. Oxalate and formate existed in the fine mode, while succinate showed a bimodal distribution. Nutrient elements including Fe, Mn and Cd showed a bimodal distribution, at both submicron and supermicron size ranges. While Zn was mainly accumulated at 1.0-3.2 μm over coastal East Antarctica, both Zn and Cd mainly existed in the fine mode with a concentration peak at <0.49 μm over the Southern Ocean. Different

  2. Size distribution of linear and helical polymers in actin solution analyzed by photon counting histogram.

    PubMed

    Terada, Naofumi; Shimozawa, Togo; Ishiwata, Shin'ichi; Funatsu, Takashi

    2007-03-15

    Actin is a ubiquitous protein that is a major component of the cytoskeleton, playing an important role in muscle contraction and cell motility. At steady state, actin monomers and filaments (F-actin) coexist, and actin subunits continuously attach and detach at the filament ends. However, the size distribution of actin oligomers in F-actin solution has never been clarified. In this study, we investigated the size distribution of actin oligomers using photon-counting histograms. For this purpose, actin was labeled with a fluorescent dye, and the emitted photons were detected by confocal optics (the detection volume was of femtoliter (fL) order). Photon-counting histograms were analyzed to obtain the number distribution of actin oligomers in the detection area from their brightness, assuming that the brightness of an oligomer was proportional to the number of protomers. We found that the major populations at physiological ionic strength were 1-5mers. For data analysis, we successfully applied the theory of linear and helical aggregations of macromolecules. The model postulates three states of actin, i.e., monomers, linear polymers, and helical polymers. Here we obtained three parameters: the equilibrium constants for polymerization of linear polymers, K(l)=(5.2 +/- 1.1) x 10(6) M(-1), and helical polymers, K(h)=(1.6 +/- 0.5) x 10(7) M(-1); and the ratio of helical to linear trimers, gamma = (3.6 +/- 2.3) x 10(-2). The excess free energy of transforming a linear trimer to a helical trimer, which is assumed to be a nucleus for helical polymers, was calculated to be 2.0 kcal/mol. These analyses demonstrate that the oligomeric phase at steady state is predominantly composed of linear 1-5mers, and the transition from linear to helical polymers occurs on the level of 5-7mers. PMID:17172301

  3. Size effect on transfection and cytotoxicity of nanoscale plasmid DNA/polyethyleneimine complexes for aerosol gene delivery

    NASA Astrophysics Data System (ADS)

    Hoon Byeon, Jeong; Kim, Jang-Woo

    2014-02-01

    Nanoscale plasmid DNA (pDNA)/polyethyleneimine (PEI) complexes were fabricated in the aerosol state using a nebulization system consisting of a collison atomizer and a cool-walled diffusion dryer. The aerosol fabricated nanoscale complexes were collected and employed to determine fundamental properties of the complexes, such as size, structure, surface charge, and in vitro gene transfection efficiency and cytotoxicity. The results showed that mass ratio between pDNA and PEI should be optimized to enhance gene transfection efficiency without a significant loss of cell viability. These findings may support practical advancements in the field of nonviral gene delivery.

  4. Size effect on transfection and cytotoxicity of nanoscale plasmid DNA/polyethyleneimine complexes for aerosol gene delivery

    SciTech Connect

    Hoon Byeon, Jeong; Kim, Jang-Woo

    2014-02-03

    Nanoscale plasmid DNA (pDNA)/polyethyleneimine (PEI) complexes were fabricated in the aerosol state using a nebulization system consisting of a collison atomizer and a cool-walled diffusion dryer. The aerosol fabricated nanoscale complexes were collected and employed to determine fundamental properties of the complexes, such as size, structure, surface charge, and in vitro gene transfection efficiency and cytotoxicity. The results showed that mass ratio between pDNA and PEI should be optimized to enhance gene transfection efficiency without a significant loss of cell viability. These findings may support practical advancements in the field of nonviral gene delivery.

  5. Comparison of Toxicity and Deposition of Nano-Sized Carbon Black Aerosol Prepared With or Without Dispersing Sonication

    PubMed Central

    Kang, Mingu; Han, Jeong-Hee

    2013-01-01

    Nanotoxicological research has shown toxicity of nanomaterials to be inversely related to particle size. However, the contribution of agglomeration to the toxicity of nanomaterials has not been sufficiently studied, although it is known that agglomeration is associated with increased nanomaterial size. In this study, we prepared aerosols of nano-sized carbon black by 2 different ways to verify the effects of agglomeration on the toxicity and deposition of nano-sized carbon black. The 2 methods of preparation included the carbon black dispersion method that facilitated clustering without sonication and the carbon black dispersion method involving sonication to achieve scattering and deagglomeration. Male Sprague-Dawley rats were exposed to carbon black aerosols 6 hr a day for 3 days or for 2 weeks. The median mass aerodynamic diameter of carbon black aerosols averaged 2.08 μm (for aerosol prepared without sonication; group N) and 1.79 μm (for aerosol prepared without sonication; group S). The average concentration of carbon black during the exposure period for group N and group S was 13.08 ± 3.18 mg/m3 and 13.67 ± 3.54 mg/ m3, respectively, in the 3-day experiment. The average concentration during the 2-week experiment was 9.83 ± 3.42 mg/m3 and 9.08 ± 4.49 mg/m3 for group N and group S, respectively. The amount of carbon black deposition in the lungs was significantly higher in group S than in group N in both 3-day and 2-week experiments. The number of total cells, macrophages and polymorphonuclear leukocytes in the bronchoalveolar lavage (BAL) fluid, and the number of total white blood cells and neutrophils in the blood in the 2- week experiment were significantly higher in group S than in normal control. However, differences were not found in the inflammatory cytokine levels (IL-1β, TNF-α, IL-6, etc.) and protein indicators of cell damage (albumin and lactate dehydrogenase) in the BAL fluid of both group N and group S as compared to the normal control. In

  6. Size segregated mass concentration and size distribution of near surface aerosols over a tropical Indian semi-arid station, Anantapur: Impact of long range transport.

    PubMed

    Raghavendra Kumar, K; Narasimhulu, K; Balakrishnaiah, G; Suresh Kumar Reddy, B; Rama Gopal, K; Reddy, R R; Moorthy, K Krishna; Suresh Babu, S

    2009-10-15

    Regular measurements of size segregated as well as total mass concentration and size distribution of near surface composite aerosols, made using a ten-channel Quartz Crystal Microbalance (QCM) cascade impactor during the period of September 2007-May 2008 are used to study the aerosol characteristics in association with the synoptic meteorology. The total mass concentration varied from 59.70+/-1.48 to 41.40+/-1.72 microg m(-3), out of which accumulation mode dominated by approximately 50%. On a synoptic scale, aerosol mass concentration in the accumulation (submicron) mode gradually increased from an average low value of approximately 26.92+/-1.53 microg m(-3) during the post monsoon season (September-November) to approximately 34.95+/-1.32 microg m(-3) during winter (December-February) and reaching a peak value of approximately 43.56+/-1.42 microg m(-3) during the summer season (March-May). On the contrary, mass concentration of aerosols in the coarse (supermicron) mode increased from approximately 9.23+/-1.25 microg m(-3)during post monsoon season to reach a comparatively high value of approximately 25.89+/-1.95 microg m(-3) during dry winter months and a low value of approximately 8.07+/-0.76 microg m(-3) during the summer season. Effective radius, a parameter important in determining optical (scattering) properties of aerosol size distribution, varied between 0.104+/-0.08 microm and 0.167+/-0.06 microm with a mean value of 0.143+/-0.01 microm. The fine mode is highly reduced during the post monsoon period and the large and coarse modes continue to remain high (replenished) so that their relative dominance increases. It can be seen that among the two parameters measured, correlation of total mass concentration with air temperature is positive (R(2)=0.82) compared with relative humidity (RH) (R(2)=0.75). PMID:19640569

  7. Types, Sizes, Shapes and Distributions of Mars Ice and Dust Aerosols from the MGS TES Emission Phase Function Observations

    NASA Astrophysics Data System (ADS)

    Clancy, R. T.; Wolff, M. J.; Christensen, P. R.

    2001-12-01

    A full Mars year (1999-2001) of emission phase function (EPF observations from Mars Global Surveyor (MGS) Thermal Emission Spectrometer (TES) provide the most complete study of Mars dust and ice aerosol properties to date. TES visible (solar band average) and infrared spectral (6-30 micron, 10 invcm res) EPF sequences are analyzed self-consistently with detailed multiple scattering radiative transfer (RT) codes to obtain first-time seasonal/latitudinal distributions of aerosol visible optical depths, particle sizes, and single scattering phase functions. As a consequence of the combined angular and wavelength coverage, we are able to define two distinct ice cloud types at 45S-45N latitudes on Mars. Type 1 ice clouds exhibit small particle sizes (1-2 micron radii), as well as a broad, deep minimum in side scattering indicative of aligned ice grains (see Wolff et al., 2001). Type 1 ice aerosols are most prevalent in the southern hemisphere during Mars aphelion, but also appear more widely distributed in season and latitude as topographic and high altitude (above 20 km) ice hazes. Type 2 ice clouds exhibit larger particle sizes (2-4 microns) and a much narrower side-scattering minimum, indicative of poorer grain alignment or a change in particle shape relative to the type 1 ice clouds (see Wolff et al., 2001). Type 2 ice clouds appear most prominently in the northern subtropical aphelion cloud belt, where relatively low altitudes of water vapor saturation (10 km) coincide with strong advective transport (Clancy et al., 1996). Retrieved dust particle radii of 1.5-1.8 micron are consistent with Pathfinder (Tomasko et al., 1999) and recent Viking/Mariner 9 reanalyses (e.g., size distribution B of Clancy et al., 1995). Detailed spectral modeling of the solar passband also implies agreement of EPF-derived dust single scattering albedos (ssa) with the ssa results from Tomasko et al.(table 8 therein). Spatial and seasonal changes in the dust ssa (0.92-0.95, solar band

  8. Retrieval of composition and size distribution of stratospheric aerosols with the SAGE II satellite experiment

    NASA Technical Reports Server (NTRS)

    Yue, Glenn K.; Mccormick, M. P.; Chu, W. P.

    1986-01-01

    The SAGE II satellite system was launched on October 5, 1984. It has seven radiometric channels and is beginning to provide water vapor, NO2, and O3 concentration profiles and aerosol extinction profiles at a minimum of three wavelengths. A simple, fast and operational method of retrieving characteristics of stratospheric aerosols from the water vapor and three-wavelength aerosol extinction profiles is proposed. Some examples are given to show the practicality of the scheme. Possible sources of error for the retrieved values and the limitation of the proposed method are discussed. This method may also prove applicable to the study of aerosol characteristics in other multispectral extinction measurements.

  9. Particle size distribution of aerosols sprayed from household hand-pump sprays containing fluorine-based and silicone-based compounds.

    PubMed

    Kawakami, Tsuyoshi; Isama, Kazuo; Ikarashi, Yoshiaki

    2015-01-01

    Japan has published safety guideline on waterproof aerosol sprays. Furthermore, the Aerosol Industry Association of Japan has adopted voluntary regulations on waterproof aerosol sprays. Aerosol particles of diameter less than 10 µm are considered as "fine particles". In order to avoid acute lung injury, this size fraction should account for less than 0.6% of the sprayed aerosol particles. In contrast, the particle size distribution of aerosols released by hand-pump sprays containing fluorine-based or silicone-based compounds have not been investigated in Japan. Thus, the present study investigated the aerosol particle size distribution of 16 household hand-pump sprays. In 4 samples, the ratio of fine particles in aerosols exceeded 0.6%. This study confirmed that several hand-pump sprays available in the Japanese market can spray fine particles. Since the hand-pump sprays use water as a solvent and their ingredients may be more hydrophilic than those of aerosol sprays, the concepts related to the safety of aerosol-sprays do not apply to the hand pump sprays. Therefore, it may be required for the hand-pump spray to develop a suitable method for evaluating the toxicity and to establish the safety guideline. PMID:26821469

  10. Characterization of saccharides in size-fractionated ambient particulate matter and aerosol sources: the contribution of primary biological aerosol particles (PBAPs) and soil to ambient particulate matter.

    PubMed

    Jia, Yuling; Fraser, Matthew

    2011-02-01

    Size-fractionated (equivalent to ambient PM2.5 and PM10) local soil, plant, and spore samples were collected in the Sonoran Desert near Phoenix, AZ and measured for saccharide content with the goal of characterizing ambient particulate matter sources including soil and primary biological aerosol particles (PBAPs) from plants and fungi. Different saccharide compositions were observed among soil, plant, and spore samples and between PM2.5 and PM10 fractions. The total measured nonlevoglucosan saccharide content relative to PM mass in ambient aerosols collected in a Phoenix suburb (Higley) was much higher compared to the local soil samples but much lower compared to the PBAP. The enrichment of saccharides from two saccharide-dominated PM source factors resolved by a positive matrix factorization model is also higher than the saccharide content in the size-fractionated local soil samples, but lower than that measured in the size-segregated PBAP samples. This indicates that ambient concentration of particulate saccharides at Higley was dominated by contributions from PBAPs directly injected into the atmosphere from plants and spores rather than from soil and associated biota. Our results also suggest the contribution to the fine size fraction of ambient PM from the primary biologically derived sources may be greater than previously acknowledged. PMID:21214236

  11. Solution of multifrequency lidar inverse problem for a pre-set marine aerosol size-distribution formula

    SciTech Connect

    Piskozub, J.

    1994-12-31

    The multifrequency lidar inverse problem discussed consists of calculating the size distribution of sol particles from backscattered lidar data. Sea-water (marine) aerosol is particularly well suited for this kind of study as its scattering characteristics can be accurately represented by Mie theory as its particles are almost spherical and their complex index of refraction is well known. Here, a solution of the inverse problem concerning finding aerosol size distribution for a multifrequency lidar system working on a small number of wavelengths is proposed. The solution involves a best-fit method of finding parameters in a pre-set formula of particle size distribution. A comparison of results calculated with the algorithm from experimental lidar profiles with PMS data collected in Baltic Sea coastal zone is given.

  12. Contact freezing efficiency of mineral dust aerosols studied in an electrodynamic balance: quantitative size and temperature dependence for illite particles.

    PubMed

    Hoffmann, Nadine; Duft, Denis; Kiselev, Alexei; Leisner, Thomas

    2013-01-01

    Contact freezing has long been discussed as a candidate for cloud ice formation at temperatures warmer than about -25 degrees C, but until now the molecular mechanism underlying this process has remained obscure and little quantitative information about the size and temperature dependent contact freezing properties of the various aerosol species is available. In this contribution, we present the first quantitative measurements of the freezing probability of a supercooled droplet upon a single contact with a size selected illite mineral particle. It is found that this probability is a strong function of temperature and aerosol particle size. For the particles investigated and on the minute time scale of the experiment, contact freezing indeed dominates immersion freezing for all temperatures. PMID:24601013

  13. Simultaneous retrieval of effective refractive index and density from size distribution and light scattering data: weakly absorbing aerosol

    NASA Astrophysics Data System (ADS)

    Kassianov, E.; Barnard, J.; Pekour, M.; Berg, L. K.; Shilling, J.; Flynn, C.; Mei, F.; Jefferson, A.

    2014-05-01

    We propose here a novel approach for retrieving in parallel the effective density and real refractive index of weakly absorbing aerosol from optical and size distribution measurements. Here we define "weakly absorbing" as aerosol single-scattering albedos that exceed 0.95 at 0.5 μm. The required optical measurements are the scattering coefficient and the hemispheric backscatter fraction, obtained in this work from an integrating nephelometer. The required size spectra come from a Scanning Mobility Particle Sizer and an Aerodynamic Particle Sizer. The performance of this approach is first evaluated using a sensitivity study with synthetically generated but measurement-related inputs. The sensitivity study reveals that the proposed approach is robust to random noise; additionally the uncertainties of the retrieval are almost linearly proportional to the measurement errors, and these uncertainties are smaller for the real refractive index than for the effective density. Next, actual measurements are used to evaluate our approach. These measurements include the optical, microphysical, and chemical properties of weakly absorbing aerosol which are representative of a variety of coastal summertime conditions observed during the Two-Column Aerosol Project (TCAP; http://campaign.arm.gov/tcap/). The evaluation includes calculating the root mean square error (RMSE) between the aerosol characteristics retrieved by our approach, and the same quantities calculated using the conventional volume mixing rule for chemical constituents. For dry conditions (defined in this work as relative humidity less than 55%) and sub-micron particles, a very good (RMSE ~ 3%) and reasonable (RMSE ~ 28%) agreement is obtained for the retrieved real refractive index (1.49 ± 0.02) and effective density (1.68 ± 0.21), respectively. Our approach permits discrimination between the retrieved aerosol characteristics of sub-micron and sub-10

  14. Simultaneous Retrieval of Effective Refractive Index and Density from Size Distribution and Light Scattering Data: Weakly-Absorbing Aerosol

    SciTech Connect

    Kassianov, Evgueni I.; Barnard, James C.; Pekour, Mikhail S.; Berg, Larry K.; Shilling, John E.; Flynn, Connor J.; Mei, Fan; Jefferson, Anne

    2014-10-01

    We propose here a novel approach for retrieving in parallel the effective density and real refractive index of weakly absorbing aerosol from optical and size distribution measurements. Here we define “weakly absorbing” as aerosol single-scattering albedos that exceed 0.95 at 0.5 um.The required optical measurements are the scattering coefficient and the hemispheric backscatter fraction, obtained in this work from an integrating nephelometer. The required size spectra come from a Scanning Mobility Particle Sizer and an Aerodynamic Particle Sizer. The performance of this approach is first evaluated using a sensitivity study with synthetically generated but measurement-related inputs. The sensitivity study reveals that the proposed approach is robust to random noise; additionally the uncertainties of the retrieval are almost linearly proportional to the measurement errors, and these uncertainties are smaller for the real refractive index than for the effective density. Next, actual measurements are used to evaluate our approach. These measurements include the optical, microphysical, and chemical properties of weakly absorbing aerosol which are representative of a variety of coastal summertime conditions observed during the Two-Column Aerosol Project (TCAP; http://campaign.arm.gov/tcap/). The evaluation includes calculating the root mean square error (RMSE) between the aerosol characteristics retrieved by our approach, and the same quantities calculated using the conventional volume mixing rule for chemical constituents. For dry conditions (defined in this work as relative humidity less than 55%) and sub-micron particles, a very good (RMSE~3%) and reasonable (RMSE~28%) agreement is obtained for the retrieved real refractive index (1.49±0.02) and effective density (1.68±0.21), respectively. Our approach permits discrimination between the retrieved aerosol characteristics of sub-micron and sub-10micron particles. The evaluation results also reveal that the

  15. Size-resolved, real-time measurement of water-insoluble aerosols in metropolitan Atlanta during the summer of 2004

    NASA Astrophysics Data System (ADS)

    Greenwald, Roby; Bergin, Michael H.; Weber, Rodney; Sullivan, Amy

    During the month of August 2004, the size-resolved number concentration of water-insoluble aerosols (WIA) from 0.25 to 2.0 μm was measured in real-time in the urban center of Atlanta, GA. Simultaneous measurements were performed for the total aerosol size distribution from 0.1 to 2.0 μm, the elemental and organic carbon mass concentration, the aerosol absorption coefficient, and the aerosol scattering coefficient at a dry (RH=30%) humidity. The mean aerosol number concentration in the size range 0.1-2.0 μm was found to be 360±175 cm -3, but this quantity fluctuated significantly on time scales of less than one hour and ranged from 25 to 1400 cm -3 during the sample period. The mean WIA concentration (0.25-2.0 μm) was 13±7 cm -3 and ranged from 1 to 60 cm -3. The average insoluble fraction in the size range 0.25-2.0 μm was found to be 4±2.5% with a range of 0.3-38%. The WIA population was found to follow a consistent diurnal pattern throughout the month with concentration maxima concurring with peaks in vehicular traffic flow. WIA concentration also responded to changes in meteorological conditions such as boundary layer depth and precipitation events. The temporal variability of the absorption coefficient followed an identical pattern to that of WIA and ranged from below the detection limit to 55 Mm -1 with a mean of 8±6 Mm -1. The WIA concentration was highly correlated with both the absorption coefficient and the elemental carbon mass concentration, suggesting that WIA measurements are dominated by fresh emissions of elemental carbon. For both the total aerosol and the WIA size distributions, the maximum number concentration was observed at the smallest sizes; however the WIA size distribution also exhibited a peak at 0.45 μm which was not observed in the total population. Over 60% of the particles greater than 1.0 μm were observed to be insoluble in the water sampling stream used by this instrumentation. Due to the refractive properties of black

  16. Comparative Climate Responses of Anthropogenic Greenhouse Gases, All Major Aerosol Components, Black Carbon, and Methane, Accounting for the Evolution of the Aerosol Mixing State and of Clouds/Precipitation from Multiple Aerosol Size Distributions

    NASA Astrophysics Data System (ADS)

    Jacobson, M. Z.

    2005-12-01

    Several modeling studies to date have simulated the global climate response of anthropogenic greenhouse gases and bulk (non-size-resolved) sulfate or generic aerosol particles together, but no study has examined the climate response of greenhouse gases simultaneously with all major size- and composition resolved aerosol particle components. Such a study is important for improving our understanding of the effects of anthropogenic pollutants on climate. Here, the GATOR-GCMOM model is used to study the global climate response of (a) all major greenhouse gases and size-resolved aerosol components, (b) all major greenhouse gases alone, (c) fossil-fuel soot (black carbon, primary organic matter, sulfuric acid, bisulfate, sulfate), and (d) methane. Aerosol components treated in all simulations included water, black carbon, primary organic carbon, secondary organic carbon, sulfuric acid, bisulfate, sulfate, nitrate, chloride, ammonium, sodium, hydrogen ion, soil dust, and pollen/spores. Fossil-fuel soot (FFS) was emitted into its own size distribution. All other components, including biofuel and biomass soot, sea-spray, soil dust, etc., were emitted into a second distribution (MIX). The FFS distribution grew by condensation of secondary organic matter and sulfuric acid, hydration of water, and dissolution of nitric acid, ammonia, and hydrochloric acid. It self-coagulated and heterocoagulated with the MIX distribution, which also grew by condensation, hydration, and dissolution. Treatment of separate distributions for FFS allowed FFS to evolve from an external mixture to an internal mixture. In both distributions, black carbon was treated as a core component for optical calculations. Both aerosol distributions served as CCN during explicit size-resolved cloud formation. The resulting clouds grew by coagulation and condensation, coagulated with interstitial aerosol particles, and fell to the surface as rain and snow, carrying aerosol constituents with them. Thus, cloud

  17. Tuning Aerosol Particle Size Distribution of Metered Dose Inhalers Using Cosolvents and Surfactants

    PubMed Central

    Saleem, Imran Y.; Smyth, Hugh D. C.

    2013-01-01

    Objectives. The purpose of these studies was to understand the influence of cosolvent and surfactant contributions to particle size distributions emitted from solution metered dose inhalers (pMDIs) based on the propellant HFA 227. Methods. Two sets of formulations were prepared: (a) pMDIs-HFA 227 containing cosolvent (5–15% w/w ethanol) with constant surfactant (pluronic) concentration and (b) pMDIs-HFA 227 containing surfactant (0–5.45% w/w pluronic) with constant cosolvent concentration. Particle size distributions emitted from these pMDIs were analyzed using aerodynamic characterization (inertial impaction) and laser diffraction methods. Results. Both cosolvent and surfactant concentrations were positively correlated with median particle sizes; that is, drug particle size increased with increasing ethanol and pluronic concentrations. However, evaluation of particle size distributions showed that cosolvent caused reduction in the fine particle mode magnitude while the surfactant caused a shift in the mode position. These findings highlight the different mechanisms by which these components influence droplet formation and demonstrate the ability to utilize the different effects in formulations of pMDI-HFA 227 for independently modulating particle sizes in the respirable region. Conclusion. Potentially, the formulation design window generated using these excipients in combination could be used to match the particle size output of reformulated products to preexisting pMDI products. PMID:23984381

  18. A Year-round Observation of Size Distribution of Aerosol Particles at the Cape Ochiishi, Japan

    NASA Astrophysics Data System (ADS)

    Miura, K.; Mukai, H.; Hashimoto, S.; Uematsu, M.

    2010-12-01

    New particle formation by nucleation of gas-phase compounds emitted from marine biogenic sources is very important for climate change. To clarify the mechanism of the formation, size distributions of submicron aerosols have been measured at the Cape Ochiishi, facing the North Western Pacific Ocean where primary productivity is high. A test observation was done from 22nd May to 18th June 2008 and a year-round observation has been performed from 16th October 2009 to 7th September 2010. The size distribution from 10 nm to 487 nm in diameter was measured with a scanning mobility particle sizer (SMPS, TSI 3034). Sample air was dried to lower than 40%. Transport of sulfate, organic carbon (OC), and black carbon (BC) was estimated with Chemical weather FORecasting System (CFORS), developed by Prof. Uno, Kyushu University, Japan. Existence of inversion layer was estimated with temperature profile measured at surface, 10m, 30m, and 50m in altitude. The burst of the particles smaller than 20nm in diameter continuing longer than 3 hrs was observed ten times until 3rd November 2009. Two were observed in early summer and the other was in autumn. Banana shape was faintly observed five times. Transport of sulfate, OC, and BC was observed 3, 8, 9 times, respectively. Source of air mass was estimated with these elements, weather map, and wind direction. Five air masses were estimated to continental. Clearly nucleation related to marine sources was not observed. The size distribution of burst evens of maritime and continental air mass showed the shift of mode to larger diameter. Strong inversion of temperature was observed once. The value of size distribution did not show high. Minimum value of size distribution was observed in the strong rain on 27th October. Acknowledgments This study was partly supported by the Grant-in-Aids for Scientific Research on Priority Areas from the Ministry of Education, Culture, Sports, Science and Technology, Japan (18067005). The observation was

  19. On the concentration and size distribution of sub-micron aerosol in the Galápagos Islands

    NASA Astrophysics Data System (ADS)

    Sorribas, M.; Gómez Martín, J. C.; Hay, T. D.; Mahajan, A. S.; Cuevas, C. A.; Agama Reyes, M. V.; Paredes Mora, F.; Gil-Ojeda, M.; Saiz-Lopez, A.

    2015-12-01

    During the CHARLEX campaign in the Galápagos Islands, a Scanning Particle Mobility Sizer was deployed on San Cristobal Island in July-August 2011 to carry out size-resolved measurements of the concentration of submicron aerosols. To our knowledge these are the first measurements of aerosol concentrations in this unique environment. The particles with marine origin displayed a tri-modal number size distribution with peak diameters of 0.016 μm, 0.050 μm and 0.174 μm and a cloud-processed intermodal minimum at 0.093 μm. The mean total aerosol number concentration for the marine contribution was 470 ± 160 cm-3. A low particle concentration of 70 ± 50 cm-3 for the nucleation size range was measured, but no evidence of new particle production in the atmospheric marine boundary layer (MBL) was observed. The concentration of the Aitken size mode was found to be related to aerosol entrainment from the free troposphere off the coast of Chile followed by transport within the MBL to the Galápagos Islands. Cloud processing may activate the particles in the Aitken size range, growing through 'in-cloud' sulphate production and increasing the particle concentration in the accumulation size range. The 0.093 μm cloud processed minima suggests that the critical supersaturation at which the particle is activated to a cloud droplet is in the 0.14-0.21% range. The daytime marine particle background concentration was influenced by human activity around the sampling site, as well as by new particle formation triggered by biogenic emissions from the vegetation cover of the island's semiarid lowlands. Effective CCN formation may play a role in the formation and properties of the stratus clouds, which permanently cover the top of the windward side of the islands and establish one of their characteristic climatic bands.

  20. Aerosol composition at Chacaltaya, Bolivia, as determined by size-fractionated sampling

    NASA Astrophysics Data System (ADS)

    Adams, F.; van Espen, P.; Maenhaut, W.

    Thirty-four cascade-impactor samples were collected between September 1977 and November 1978 at Chacaltaya, Bolivia. The concentrations of 25 elements were measured for the six impaction stages of each sample by means of energy-dispersive X-ray fluorescence and proton-induced X-ray emission analysis. The results indicated that most elements are predominantly associated with a unimodal coarse-particle soil-dustdispersion component. Also chlorine and the alkali and alkaline earth elements belong to this group. The anomalously enriched elements (S, Br and the heavy metals Cu, Zn, Ga, As, Se, Pb and Bi) showed a bimodal size distribution. Correlation coefficient calculations and principal component analysis indicated the presence in the submicrometer aerosol mode of an important component, containing S, K, Zn, As and Br, which may originate from biomass burning. For certain enriched elements (i.e. Zn and perhaps Cu) the coarse-particle enrichments observed may be the result of the true crust-air fractionation during soil-dust dispersion.

  1. Elemental composition of size-fractionated urban aerosol collected in Florence, Italy; preliminary results

    NASA Astrophysics Data System (ADS)

    Del Carmine, P.; Lucarelli, F.; Mandò, P. A.; Valerio, M.; Prati, P.; Zucchiatti, A.

    1999-04-01

    An extensive investigation is in progress aiming at the characterisation of the air particulate composition in Florence. We present here the preliminary results concerning the analysis of size-fractionated aerosol samples taken by two-stage streaker samplers in two sites characterised by different urban settings (one in a heavy traffic area, one in a green area). The sampling period (21 January-22 February) includes two days during which the Municipality of Florence has banned the circulation of non-catalytic cars, due to the increase of NO 2 above the "recommended safety values". Hourly concentrations of 20 elements from Na to Pb were determined using the external beam PIXE facility of the I.N.F.N. Van de Graaff accelerator at the Physics Department of the Florence University. Factor analysis on the data set confirms that traffic is the main source of atmospheric pollution in Florence. The ban of non-catalytic cars seems to have produced no effect on the concentration of detected elements (in particular Pb and Br).

  2. Application of the LSQR algorithm in non-parametric estimation of aerosol size distribution

    NASA Astrophysics Data System (ADS)

    He, Zhenzong; Qi, Hong; Lew, Zhongyuan; Ruan, Liming; Tan, Heping; Luo, Kun

    2016-05-01

    Based on the Least Squares QR decomposition (LSQR) algorithm, the aerosol size distribution (ASD) is retrieved in non-parametric approach. The direct problem is solved by the Anomalous Diffraction Approximation (ADA) and the Lambert-Beer Law. An optimal wavelength selection method is developed to improve the retrieval accuracy of the ASD. The proposed optimal wavelength set is selected by the method which can make the measurement signals sensitive to wavelength and decrease the degree of the ill-condition of coefficient matrix of linear systems effectively to enhance the anti-interference ability of retrieval results. Two common kinds of monomodal and bimodal ASDs, log-normal (L-N) and Gamma distributions, are estimated, respectively. Numerical tests show that the LSQR algorithm can be successfully applied to retrieve the ASD with high stability in the presence of random noise and low susceptibility to the shape of distributions. Finally, the experimental measurement ASD over Harbin in China is recovered reasonably. All the results confirm that the LSQR algorithm combined with the optimal wavelength selection method is an effective and reliable technique in non-parametric estimation of ASD.

  3. The generation of diesel exhaust particle aerosols from a bulk source in an aerodynamic size range similar to atmospheric particles

    PubMed Central

    Cooney, Daniel J; Hickey, Anthony J

    2008-01-01

    The influence of diesel exhaust particles (DEP) on the lungs and heart is currently a topic of great interest in inhalation toxicology. Epidemiological data and animal studies have implicated airborne particulate matter and DEP in increased morbidity and mortality due to a number of cardiopulmonary diseases including asthma, chronic obstructive pulmonary disorder, and lung cancer. The pathogeneses of these diseases are being studied using animal models and cell culture techniques. Real-time exposures to freshly combusted diesel fuel are complex and require significant infrastructure including engine operations, dilution air, and monitoring and control of gases. A method of generating DEP aerosols from a bulk source in an aerodynamic size range similar to atmospheric DEP would be a desirable and useful alternative. Metered dose inhaler technology was adopted to generate aerosols from suspensions of DEP in the propellant hydrofluoroalkane 134a. Inertial impaction data indicated that the particle size distributions of the generated aerosols were trimodal, with count median aerodynamic diameters less than 100 nm. Scanning electron microscopy of deposited particles showed tightly aggregated particles, as would be expected from an evaporative process. Chemical analysis indicated that there were no major changes in the mass proportion of 2 specific aromatic hydrocarbons (benzo[a]pyrene and benzo[k]fluoranthene) in the particles resulting from the aerosolization process. PMID:19337412

  4. Influence of Particle Size on Persistence and Clearance of Aerosolized Silver Nanoparticles in the Rat Lung

    PubMed Central

    Anderson, Donald S.; Patchin, Esther S.; Silva, Rona M.; Uyeminami, Dale L.; Sharmah, Arjun; Guo, Ting; Das, Gautom K.; Brown, Jared M.; Shannahan, Jonathan; Gordon, Terry; Chen, Lung Chi; Pinkerton, Kent E.; Van Winkle, Laura S.

    2015-01-01

    The growing use of silver nanoparticles (AgNPs) in consumer products raises concerns about potential health effects. This study investigated the persistence and clearance of 2 different size AgNPs (20 and 110 nm) delivered to rats by single nose-only aerosol exposures (6 h) of 7.2 and 5.4 mg/m3, respectively. Rat lung tissue was assessed for silver accumulations using inductively-coupled plasma mass spectrometry (ICP-MS), autometallography, and enhanced dark field microscopy. Involvement of tissue macrophages was assessed by scoring of silver staining in bronchoalveolar lavage fluid (BALF). Silver was abundant in most macrophages at 1 day post-exposure. The group exposed to 20 nm AgNP had the greatest number of silver positive BALF macrophages at 56 days post-exposure. While there was a significant decrease in the amount of silver in lung tissue at 56 days post-exposure compared with 1 day following exposure, at least 33% of the initial delivered dose was still present for both AgNPs. Regardless of particle size, silver was predominantly localized within the terminal bronchial/alveolar duct junction region of the lung associated with extracellular matrix and within epithelial cells. Inhalation of both 20 and 110 nm AgNPs resulted in a persistence of silver in the lung at 56 days post-exposure and local deposition as well as accumulation of silver at the terminal bronchiole alveolar duct junction. Further the smaller particles, 20 nm AgNP, produced a greater silver burden in BALF macrophages as well as greater persistence of silver positive macrophages at later timepoints (21 and 56 days). PMID:25577195

  5. Size and mass distributions of ground-level sub-micrometer biomass burning aerosol from small wildfires

    NASA Astrophysics Data System (ADS)

    Okoshi, Rintaro; Rasheed, Abdur; Chen Reddy, Greeshma; McCrowey, Clinton J.; Curtis, Daniel B.

    2014-06-01

    Biomass burning emits large amounts of aerosol particles globally, influencing human health and climate, but the number and size of the particles is highly variable depending on fuel type, burning and meteorological conditions, and secondary reactions in the atmosphere. Ambient measurements of aerosol during wildfire events can therefore improve our understanding of particulate matter produced from biomass burning. In this study, time-resolved sub-micrometer ambient aerosol size and mass distributions of freshly emitted aerosol were measured for three biomass burning wildfire events near Northridge, California, located in the highly populated San Fernando Valley area of Los Angeles. One fire (Marek) was observed during the dry Santa Ana conditions that are typically present during large Southern California wildfires, but two smaller fires (Getty and Camarillo) were observed during the more predominant non-Santa Ana weather conditions. Although the fires were generally small and extinguished quickly, they produced particle number concentrations as high as 50,000 cm-3 and mass concentrations as large as 150 μg cm-3, well above background measurements and among the highest values observed for fires in Southern California. Therefore, small wildfires can have a large impact on air quality if they occur near urban areas. Particle number distributions were lognormal, with peak diameters in the accumulation mode at approximately 100 nm. However, significant Aitken mode and nucleation mode particles were observed in bimodal distributions for one fire. Significant variations in the median diameter were observed over time, as particles generally became smaller as the fires were contained. The results indicate that it is likely that performing mass measurements alone could systematically miss detection of the smaller particles and size measurements may be better suited for studies of ambient biomass burning events. Parameters of representative unimodal and bimodal lognormal

  6. Impacts of Venturi Turbulent Mixing on the Size Distribution of Sodium Chloride and Dioctyl-Phthalate Aerosols

    SciTech Connect

    Cheng, M.-D.; Wainman, T.; Storey, J.

    2000-08-01

    Internal combustion engines are a major source of airborne particulate matter (PM). The size of the engine PM is in the sub-micrometer range. The number of engine particles per unit volume is high, normally in the range of 10{sup 12} to 10{sup 14}. To measure the size distribution of the engine particles dilution of an aerosol sample is required. A diluter utilizing a venturi ejector mixing technique is commercially available and tested. The purpose of this investigation was to determine if turbulence created by the ejector in the mini-dilutor changes the size of particles passing through it.

  7. Insights Into Water-Soluble Organic Aerosol Sources From Carbon-13 Ratios of Size Exclusion Chromatography Fractions

    NASA Astrophysics Data System (ADS)

    Ruehl, C. R.; Chuang, P. Y.; McCarthy, M. D.

    2008-12-01

    Many sources of organic aerosols have been identified and quantified, and much of this work has used individual (mosty water-insoluble) compounds as tracers of primary sources. However, most organic aerosol cannot be molecularly characterized, and the water-soluble organic carbon (WSOC) in many aerosols is thought to originate from gaseous precursors (i.e., it is secondary in nature). It can therefore be difficult to infer aerosol sources, particularly of background (i.e., aged) aerosols, and of the relatively high-MW component of aerosols. The stable isotope ratios (δ13C) of organic aerosols have been used to distinguish between sources, with lighter values (-30‰ to -25‰) interpreted as having originated from fossil fuel combustion and C4 biogenic emission, and heavier values (-25‰ to - 20‰) indicating a marine or C3 biogenic source. Most published measurements were of either total suspended particulates or PM2.5, however, and it is unknown to what extent these fractions differ from submicron WSOC. We report δ13C for submicron WSOC collected at a variety of sites, ranging from marine to polluted to background continental. Bulk marine organic δ13C ranged from -30.4 to - 27.6‰, slightly lighter than previously published results. This could be due to the elimination of supermicron cellular material or other biogenic primary emissions from the sample. Continental WSOC δ13C ranged from -19.1 to -29.8‰, with heavier values (-19.8 ± 1.0‰) in Oklahoma and lighter values at Great Smoky Mountain National Park in Tennessee (-25.8 ± 2.6‰) and Illinois (-24.5 ± 1.0‰). This likely results from the greater proportional of C3 plant material in the Oklahoma samples. In addition to bulk samples, we used size exclusion chromatography (SEC) to report δ13C of organic aerosols as a function of hydrodynamic diameter. Variability and magnitude of hydrodynamic diameter was greatest at low SEC pH, indicative of the acidic character of submicron WSOC. Tennessee

  8. The mathematical principles and design of the NAIS - a spectrometer for the measurement of cluster ion and nanometer aerosol size distributions

    NASA Astrophysics Data System (ADS)

    Mirme, S.; Mirme, A.

    2011-12-01

    The paper describes the Nanometer aerosol and Air Ion Spectrometer (NAIS) - a multi-channel aerosol instrument capable of measuring the distribution of ions (charged particles and cluster ions) of both polarities in the electric mobility range from 3.2 to 0.0013 cm2 V-1 s-1 and the distribution of aerosol particles in the size range from 2.0 to 40 nm. We introduce the principles of design, data processing and spectrum deconvolution of the instrument.

  9. Effects of Ageing on Aerosol Composition and Size Distribution Based on Regional Scale Aircraft Observations During the 2002 and 2004 ICARTT Campaigns

    NASA Astrophysics Data System (ADS)

    Kleinman, L.; Daum, P.; Springston, S.; Lee, Y.; Wang, J.

    2005-12-01

    In the summers of 2002 and 2004 the DOE G-1 aircraft was used to sample aerosols and aerosol precursors in the Midwest and Eastern U.S. We present data on the spatial distribution of aerosols and their physical and chemical properties. Most of the sub-micron size aerosol consists of organics and sulfate. Only a minor fraction of the organic aerosol can be attributed to primary emissions. Formation of secondary organic aerosol is observed as an increase in the organic to CO ratio as a function of photochemical age. Organic aerosol is measured using an Aerodyne Aerosol Mass Spectrometer (AMS). We present comparisons between the AMS and a PCASP, DMA, and nephelometer - as this bears upon our conclusions. Production of aerosol sulfate can likewise be observed as a change in the sulfate to CO ratio but is more easily studied by following the time evolution of a point source plume such as was done for the Homer and Keystone power plants, located east of Pittsburgh. Concomitant with the addition of aerosol mass are changes in size spectra and optical properties.

  10. Source quantification of size and season resolved aerosols in a semi-urban area of Indo-Gangetic plain, India

    NASA Astrophysics Data System (ADS)

    Hooda, R. K.; Hyvärinen, A.; Gilardoni, S.; Sharma, V.; Vestenius, M.; Kerminen, V.; Vignati, E.; Kulmala, M. T.; Lihavainen, H.

    2012-12-01

    This study describes a one year measurements of size-segregated aerosols at a semi-urban site in Indo-Gangetic plain (IGP), India, South Asia with focus on source quantification applied to organic and inorganic chemical species data using Positive Matrix Factorization (PMF), trajectory analysis and conditional probability function (CPF) methods. The campaign was planned in the framework of the European Integrated project on Aerosol Cloud Climate and Air Quality interactions (EUCAARI) project. In light of the above, Finnish Meteorological Institute (FMI), The Energy and Resources Institute (TERI) and Joint Research Centre (JRC) conducted aerosol mass measurements in Gual Pahari, India from April 2008 to March 2009. The average mass concentrations of fine (PM2.5) and coarse (PM2.5-10) aerosols are higher during the postmonsoon (October-November) and winter (December- February) compared to that during the summer season (March-May). Fine and coarse fraction concentrations observed are higher during the post-monsoon & winter months due to low and stable boundary layer. Concentrations decrease in March-June due to increasing temperatures and a higher boundary layer. The lowest concentrations are during the rainy months (June to August/Sept) due to wet removal. OC and EC fraction is higher in PM2.5. EC in in PM2.5 is 9%, and in PM2.5-10 size EC is 2%. OC contribution is about 36% of fine aerosol mass. High OC could be attributed to enhanced combustion sources and the meteorological conditions during winter period. High OC to EC ratio during postmonsoon and winter also supports higher secondary organic aerosol (SOA) formation in these seasons. Secondary organic carbon (SOC) calculated is 42% of the annual average of total OC in coarse fraction. SOC to total OC is highest in postmonsoon (53%), winter (34%) and followed by 29% in summer and monsoon seasons. 24-hr speciated fine and coarse aerosols annual data was used for source identification and quantification studies with

  11. Source attribution of aerosol size distributions and model evaluation using Whistler Mountain measurements and GEOS-Chem-TOMAS simulations

    NASA Astrophysics Data System (ADS)

    D'Andrea, S. D.; Ng, J. Y.; Kodros, J. K.; Atwood, S. A.; Wheeler, M. J.; Macdonald, A. M.; Leaitch, W. R.; Pierce, J. R.

    2016-01-01

    Remote and free-tropospheric aerosols represent a large fraction of the climatic influence of aerosols; however, aerosol in these regions is less characterized than those polluted boundary layers. We evaluate aerosol size distributions predicted by the GEOS-Chem-TOMAS global chemical transport model with online aerosol microphysics using measurements from the peak of Whistler Mountain, British Columbia, Canada (2182 m a.s.l., hereafter referred to as Whistler Peak). We evaluate the model for predictions of aerosol number, size, and composition during periods of free-tropospheric (FT) and boundary-layer (BL) influence at "coarse" 4° × 5° and "nested" 0.5° × 0.667° resolutions by developing simple FT/BL filtering techniques. We find that using temperature as a proxy for upslope flow (BL influence) improved the model-measurement comparisons. The best threshold temperature was around 2 °C for the coarse simulations and around 6 °C for the nested simulations, with temperatures warmer than the threshold indicating boundary-layer air. Additionally, the site was increasingly likely to be in cloud when the measured relative humidity (RH) was above 90 %, so we do not compare the modeled and measured size distributions during these periods. With the inclusion of these temperature and RH filtering techniques, the model-measurement comparisons improved significantly. The slope of the regression for N80 (the total number of particles with particle diameter, Dp, > 80 nm) in the nested simulations increased from 0.09 to 0.65, R2 increased from 0.04 to 0.46, and log-mean bias improved from 0.95 to 0.07. We also perform simulations at the nested resolution without Asian anthropogenic emissions and without biomass-burning emissions to quantify the contribution of these sources to aerosols at Whistler Peak (through comparison with simulations with these emissions on). The long-range transport of Asian anthropogenic aerosol was found to be significant throughout all particle

  12. Source attribution of aerosol size distributions and model evaluation using Whistler Mountain measurements and GEOS-Chem-TOMAS simulations

    NASA Astrophysics Data System (ADS)

    D'Andrea, S. D.; Ng, J. Y.; Kodros, J. K.; Atwood, S. A.; Wheeler, M. J.; Macdonald, A. M.; Leaitch, W. R.; Pierce, J. R.

    2015-09-01

    Remote and free tropospheric aerosols represent a large fraction of the climatic influence of aerosols; however, aerosol in these regions is less characterized than those polluted boundary layers. We evaluate aerosol size distributions predicted by the GEOS-Chem-TOMAS global chemical transport model with online aerosol microphysics using measurements from the peak of Whistler Mountain, BC, Canada (2182 m a.s.l.). We evaluate the model for predictions of aerosol number, size and composition during periods of free tropospheric (FT) and boundary-layer (BL) influence at "coarse" 4° × 5° and "nested" 0.5° × 0.667° resolutions by developing simple FT/BL filtering techniques. We find that using temperature as a proxy for upslope flow (BL influence) improved the model measurement comparisons. The best threshold temperature was around 2 °C for the coarse simulations and around 6 °C for the nested simulations, with temperatures warmer than the threshold indicating boundary-layer air. Additionally, the site was increasingly likely to be in-cloud when the measured RH was above 90 %, so we do not compare the modeled and measured size distributions during these periods. With the inclusion of these temperature and RH filtering techniques, the model-measurement comparisons improved significantly. The slope of the regression for N80 (the total number of particles with particle diameter, Dp > 80 nm) in the nested simulations increased from 0.09 to 0.65, R2 increased from 0.04 to 0.46, and log-mean bias improved from 0.95 to 0.07. We also perform simulations at the nested resolution without Asian anthropogenic (AA) emissions and without biomass-burning (BB) emissions to quantify the contribution of these sources to aerosols at Whistler Peak (through comparison with simulations with these emissions on). The long-range transport of AA aerosol was found to be significant throughout all particle number concentrations, and increased the number of particles larger than 80 nm (N80

  13. Aerosols Collected at a Tropical Marine Environment: Size-Resolved Chemical Composition Using IC, TOC, and Thermal-Optical Analyses

    NASA Astrophysics Data System (ADS)

    Morales-García, F.; Mayol-Bracero, O. L.; Repollet-Pedrosa, M.; Kasper-Giebl, A.; Ramírez-Santa Cruz, C.; Puxbaum, H.

    2009-05-01

    Size-resolved chemical characterization was performed on aerosol samples collected at two different marine sites in the tropics: Dian Point (DP), Antigua and Cape San Juan (CSJ), Puerto Rico. A 13-stage Dekati low- pressure impactor (Dp 0.1 to 10 μm), a 10-stage micro-orifice uniform deposit impactor (Dp 0.054 to 18 μm), and stacked-filter units (Dp < 1.7 μm) were used to collect the samples. Na+, NH4+, K+, Mg2+, Ca2+, Cl-, NO2-, NO3-, SO42-, acetate, formate, malonate, and oxalate were determined using ion chromatography (IC). Thermal-optical analysis (TOA) was used to determine the concentrations of aerosol total carbon (TC), organic carbon (OC), and elemental carbon (EC). Five-day back trajectories calculated using NOAA's HYSPLIT (HYbrid Single-Particle Lagrangian Integrated Trajectory) model identified air masses coming from the North Atlantic (maritime air), Northwest Africa (desert dust), and North America (anthropogenic pollution). Size-resolved chemical characterization of aerosol samples using IC and TOA confirmed that aerosols become aged as they are transported to the Caribbean and their composition depends on the air mass origin. Gravimetric analyses showed that average fine mass concentrations for CSJ station were higher than for DP station (CSJ: 1.9 μg m-3; DP: 1.2 μg m-3). The aerosol chemical composition changed with air masses of different origin and with different pollution levels. In both locations the predominant water-soluble ions in the fine aerosol fraction were Cl-, Na+, and SO42-. Sulphate was observed in higher concentrations during the polluted case and particulate organic matter concentrations were higher for the maritime case. During desert dust events an increase in Ca2+ and Mg2+ of 4 and 2 times, respectively, was observed mainly in the coarse mode. Results for the size-resolved chemical composition and complete aerosol chemical apportionment including the residual mass will be presented.

  14. Assessment of source apportionment by Positive Matrix Factorization analysis on fine and coarse urban aerosol size fractions

    NASA Astrophysics Data System (ADS)

    Karanasiou, A. A.; Siskos, P. A.; Eleftheriadis, K.

    This study was conducted in order to investigate the differences observed in source profiles in the urban environment, when chemical composition parameters from different aerosol size fractions are subjected to factor analysis. Source apportionment was performed in an urban area where representative types of emission sources are present. PM 10 and PM 2 samples were collected within the Athens Metropolitan area and analysed for trace elements, inorganic ions and black carbon. Analysis by two-way and three-way Positive Matrix Factorization was performed, in order to resolve sources from data obtained for the fine and coarse aerosol fractions. A difference was observed: seven factors describe the best solution in PMF3 while six factors in PMF2. Six factors derived from PMF3 analysis correspond to those described by the PMF2 solution for the fine and coarse particles separately. These sources were attributed to road dust, marine aerosol, soil, motor vehicles, biomass burning, and oil combustion. The additional source resolved by PMF3 was attributed to a different type of road dust. Combustion sources (oil combustion and biomass burning) were correctly attributed by PMF3 solely to the fine fraction and the soil source to the coarse fraction. However, a motor vehicle's contribution to the coarse fraction was found only by three-way PMF. When PMF2 was employed in PM 10 concentrations the optimum solution included six factors. Four source profiles corresponded to the previously identified as vehicles, road dust, biomass burning and marine aerosol, while two could not be clearly identified. Source apportionment by PMF2 analysis based solely on PM 10 aerosol composition data, yielded unclear results, compared to results from PMF2 and PMF3 analyses on fine and coarse aerosol composition data.

  15. Using Effect Sizes for Research Reporting: Examples Using Item Response Theory to Analyze Differential Item Functioning

    ERIC Educational Resources Information Center

    Steinberg, Lynne; Thissen, David

    2006-01-01

    The psychological literature currently emphasizes reporting the "effect size" of research findings in addition to the outcome of any tests of significance. However, some confusion may result from the fact that there are three distinct uses of effect sizes in the psychological literature, namely, power analysis, research synthesis, and research…

  16. Impact of wildfires on size-resolved aerosol composition at a coastal California site

    NASA Astrophysics Data System (ADS)

    Maudlin, L. C.; Wang, Z.; Jonsson, H. H.; Sorooshian, A.

    2015-10-01

    Size-resolved aerosol composition measurements were conducted at a coastal site in central California during the Nucleation in California Experiment (NiCE) between July and August of 2013. The site is just east of ship and marine emission sources and is also influenced by continental pollution and wildfires, such as those near the California-Oregon border which occurred near the end of NiCE. Two micro-orifice uniform deposit impactors (MOUDIs) were used, and water-soluble and elemental compositions were measured. The five most abundant water-soluble species (in decreasing order) were chloride, sodium, non-sea salt (nss) sulfate, ammonium, and nitrate. During wildfire periods, nss K mass concentrations were not enhanced as strongly as other species in the sub-micrometer stages and even decreased in the super-micrometer stages; species other than nss K are more reliable tracers for biomass burning in this region. Chloride levels were reduced in the fire sets likely due to chloride depletion by inorganic and organic acids that exhibited elevated levels in transported plumes. During wildfire periods, the mass size distribution of most dicarboxylic acids changed from unimodal to bimodal with peaks in the 0.32 μm and 1.0-1.8 μm stages. Furthermore, sulfate's peak concentration shifted from the 0.32 μm to 0.56 μm stage, and nitrate also shifted to larger sizes (1.0 μm to 1.8-3.2 μm stages). Mass concentrations of numerous soil tracer species (e.g., Si, Fe) were strongly enhanced in samples influenced by wildfires, especially in the sub-micrometer range. Airborne cloud water data confirm that soil species were associated with fire plumes transported south along the coast. In the absence of biomass burning, cloud condensation nuclei (CCN) composition is dominated by nss sulfate and ammonium, and the water-soluble organic fraction is dominated by methanesulfonate, whereas for the samples influenced by wildfires, ammonium becomes the dominant overall species, and

  17. Reconciliation of coarse mode sea-salt aerosol particle size measurements and parameterizations at a subtropical ocean receptor site

    NASA Astrophysics Data System (ADS)

    Reid, Jeffrey S.; Brooks, Barbara; Crahan, Katie K.; Hegg, Dean A.; Eck, Thomas F.; O'Neill, Norm; de Leeuw, Gerrit; Reid, Elizabeth A.; Anderson, Kenneth D.

    2006-01-01

    In August/September of 2001, the R/P FLIP and CIRPAS Twin Otter research aircraft were deployed to the eastern coast of Oahu, Hawaii, as part of the Rough Evaporation Duct (RED) experiment. Goals included the study of the air/sea exchange, turbulence, and sea-salt aerosol particle characteristics at the subtropical marine Pacific site. Here we examine coarse mode particle size distributions. Similar to what has been shown for airborne dust, optical particle counters such as the Forward Scattering Spectrometer Probe (FSSP), Classical Scattering Aerosol Spectrometer Probe (CSASP) and the Cloud Aerosol Spectrometer (CAS) within the Cloud Aerosol and Precipitation Spectrometer (CAPS) instrument systematically overestimate particle size, and consequently volume, for sea salt particles. Ground-based aerodynamic particle sizers (APS) and AERONET inversions yield much more reasonable results. A wing pod mounted APS gave mixed results and may not be appropriate for marine boundary layer studies. Relating our findings to previous studies does much to explain the bulk of the differences in the literature and leads us to conclude that the largest uncertainty facing flux and airborne cloud/aerosol interaction studies is likely due to the instrumentation itself. To our knowledge, there does not exist an in situ aircraft system that adequately measures the ambient volume distribution of coarse mode sea salt particles. Most empirically based sea salt flux parameterizations can trace their heritage to a clearly biased measurement technique. The current "state of the art" in this field prevents any true form of clear sky radiative "closure" for clean marine environments.

  18. Metal concentration and bioaccessibility in different particle sizes of dust and aerosols to refine metal exposure assessment.

    PubMed

    Goix, Sylvaine; Uzu, Gaëlle; Oliva, Priscia; Barraza, Fiorella; Calas, Aude; Castet, Sylvie; Point, David; Masbou, Jeremy; Duprey, Jean-Louis; Huayta, Carlos; Chincheros, Jaime; Gardon, Jacques

    2016-11-01

    Refined exposure assessments were realized for children, 7-9yrs, in the mining/smelting city of Oruro, Bolivia. Aerosols (PM>2.5, PM1-2.5, PM0.4-1 and PM0.5) and dust (separated in different particle size fractions: 2000-200μm, 200-50μm, 50-20μm, 20-2μm and <2μm) were sampled on football fields highly frequented by children in both the mining and smelting areas. Trace element concentrations (Ag, As, Cd, Cu, Pb, Sb, Sn and Zn) in each size fraction of dust and aerosols, lung bioaccessibility of metals in aerosols, and gastric bioaccessibility of metals in dust were measured. Exposure was assessed considering actual external exposure (i.e. exposure pathways: metals inhaled and ingested) and simulated internal exposure (i.e., complex estimation using gastric and lung bioaccessibility, deposition and clearance of particles in lungs). Significant differences between external and simulated internal exposure were attributed to dissemblances in gastric and lung bioaccessibilities, as well as metal distribution within particle size range, revealing the importance of both parameters in exposure assessment. PMID:27344256

  19. CALIOP and AERONET Aerosol Optical Depth Comparisons: One Size Fits None

    NASA Technical Reports Server (NTRS)

    Omar, A. H.; Winker, D. M.; Tackett, J. L.; Giles, D. M.; Kar, J.; Liu, Z.; Vaughan, M. A.; Powell, K. A.; Trepte, C. R.

    2013-01-01

    We compare the aerosol optical depths (AOD) retrieved from backscatter measurements of the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) aboard the Cloud Aerosol Lidar Infrared Pathfinder Satellite Observations (CALIPSO) satellite with coincident Aerosol Robotic Network (AERONET) measurements. Overpass coincidence criteria of +/- 2 h and within a 40 km radius are satisfied at least once at 149 globally distributed AERONET sites from 2006 to 2010. Most data pairs (>80%) use AERONET measurements acquired +/- 30 min of the overpass. We examine the differences in AOD estimates between CALIOP and AERONET for various aerosol, environmental, and geographic conditions. Results show CALIOP AOD are lower than AERONET AOD especially at low optical depths as measured by AERONET (500 nm AOD<0.1). Furthermore, the median relative AOD difference between the two measurements is 25% of the AERONET AOD for AOD>0.1. Differences in AOD between CALIOP and AERONET are possibly due to cloud contamination, scene inhomogeneity, instrument view angle differences, CALIOP retrieval errors, and detection limits. Comparison of daytime to nighttime number of 5 km 60m (60m in the vertical) features detected by CALIOP show that there are 20% more aerosol features at night. We find that CALIPSO and AERONET do not agree on the cloudiness of scenes. Of the scenes that meet the above coincidence criteria, CALIPSO finds clouds in more than 45% of the coincident atmospheric columns AERONET classifies as clear.

  20. An automated analyzer to measure surface-atmosphere exchange fluxes of water soluble inorganic aerosol compounds and reactive trace gases.

    PubMed

    Thomas, Rick M; Trebs, Ivonne; Otjes, René; Jongejan, Piet A C; Ten Brink, Harry; Phillips, Gavin; Kortner, Michael; Meixner, Franz X; Nemitz, Eiko

    2009-03-01

    Here, we present a new automated instrument for semicontinuous gradient measurements of water-soluble reactive trace gas species (NH3, HNO3, HONO, HCl, and SO2) and their related aerosol compounds (NH4+, NO3-, Cl-, SO4(2-)). Gas and aerosol samples are collected simultaneously at two heights using rotating wet-annular denuders and steam-jet aerosol collectors, respectively. Online (real-time) analysis using ion chromatography (IC) for anions and flow injection analysis (FIA) for NH4+ and NH3 provide a half-hourly averaged gas and aerosol gradients within each hour. Through the use of syringe pumps, IC preconcentration columns, and high-quality purified water, the system achieves detection limits (3sigma-definition) under field conditions of typically: 136/207,135/114, 29/ 22,119/92, and 189/159 ng m(-3) for NH3/NH4+, HNO3/NO3-, HONO/ NO2-, HCl/Cl- and SO2/SO4(2-), respectively. The instrument demonstrates very good linearity and accuracy for liquid and selected gas phase calibrations over typical ambient concentration ranges. As shown by examples from field experiments, the instrument provides sufficient precision (3-9%), even at low ambient concentrations, to resolve vertical gradients and calculate surface-atmosphere exchange fluxes undertypical meteorological conditions of the atmospheric surface layer using the aerodynamic gradient technique. PMID:19350912

  1. A scaling theory for the size distribution of emitted dust aerosols suggests climate models underestimate the size of the global dust cycle

    PubMed Central

    Kok, Jasper F.

    2011-01-01

    Mineral dust aerosols impact Earth’s radiation budget through interactions with clouds, ecosystems, and radiation, which constitutes a substantial uncertainty in understanding past and predicting future climate changes. One of the causes of this large uncertainty is that the size distribution of emitted dust aerosols is poorly understood. The present study shows that regional and global circulation models (GCMs) overestimate the emitted fraction of clay aerosols (< 2 μm diameter) by a factor of ∼2–8 relative to measurements. This discrepancy is resolved by deriving a simple theoretical expression of the emitted dust size distribution that is in excellent agreement with measurements. This expression is based on the physics of the scale-invariant fragmentation of brittle materials, which is shown to be applicable to dust emission. Because clay aerosols produce a strong radiative cooling, the overestimation of the clay fraction causes GCMs to also overestimate the radiative cooling of a given quantity of emitted dust. On local and regional scales, this affects the magnitude and possibly the sign of the dust radiative forcing, with implications for numerical weather forecasting and regional climate predictions in dusty regions. On a global scale, the dust cycle in most GCMs is tuned to match radiative measurements, such that the overestimation of the radiative cooling of a given quantity of emitted dust has likely caused GCMs to underestimate the global dust emission rate. This implies that the deposition flux of dust and its fertilizing effects on ecosystems may be substantially larger than thought. PMID:21189304

  2. Assessment of African and local wind-blown dust contributions at three rural sites in SE Spain: aerosol size distribution

    NASA Astrophysics Data System (ADS)

    Orza, J. A. G.; Cabello, M.; Lidón, V.; Martínez, J.

    2009-04-01

    Aerosol number size distribution and meteorological parameters were measured at three rural sites in semiarid southeastern Spain. Number concentrations of suspended particles in 31 size bins between 0.25 and 32 m diameter were continuosly recorded with a GRIMM 190 aerosol spectrometer at: (i) a rural background (RB) location in a perennial tussock grassland, from July to October 2006; (ii) a rural site surrounded by abandoned croplands, and influenced by mineral industries and by a small paved road having a small traffic load located 30 m to the East (RA), from June to December 2007; and (iii) a rural (R) location in an agricultural plot previously cleared and then lightly leveled and compacted for future lemon-tree cultivation, from February to June 2008. Events of long range transport from North Africa to the study area (African dust outbreaks, ADOs) were identified by aerosol transport models, back-trajectories and satellite imagery. There is an increase in the concentration of particles larger than 2 m with increasing wind speed while the concentrations decrease for smaller particles at the RB and R sites. At the RA location, that increase is observed for particles in the range 1.6 - 3.5 m (the precise value depends on the wind speed) when there are West winds. Particulate resuspension is found to occur at all wind speeds, although wind threshold values can be identified by a sharp increase in particle concentrations for a range of particle sizes. Light winds entrain large particles while stronger winds additionally entrain particles of smaller size (down to 2.5 m for the highest winds). The size distributions present maxima at 1.6 and 3 m on days with ADO. Concentration for almost every particle size is higher on ADOs than on days without such events, due in part to the associated meteorological situation. This work was partially supported by the Spanish Ministerio de Educación y Ciencia under grant CGL2004-04419 (RESUSPENSE Project).

  3. Chemical characterization of size-resolved aerosols in four seasons and hazy days in the megacity Beijing of China.

    PubMed

    Sun, Kang; Liu, Xingang; Gu, Jianwei; Li, Yunpeng; Qu, Yu; An, Junling; Wang, Jingli; Zhang, Yuanhang; Hu, Min; Zhang, Fang

    2015-06-01

    Size-resolved aerosol samples were collected by MOUDI in four seasons in 2007 in Beijing. The PM10 and PM1.8 mass concentrations were 166.0±120.5 and 91.6±69.7 μg/m3, respectively, throughout the measurement, with seasonal variation: nearly two times higher in autumn than in summer and spring. Serious fine particle pollution occurred in winter with the PM1.8/PM10 ratio of 0.63, which was higher than other seasons. The size distribution of PM showed obvious seasonal and diurnal variation, with a smaller fine mode peak in spring and in the daytime. OM (organic matter=1.6×OC (organic carbon)) and SIA (secondary inorganic aerosol) were major components of fine particles, while OM, SIA and Ca2+ were major components in coarse particles. Moreover, secondary components, mainly SOA (secondary organic aerosol) and SIA, accounted for 46%-96% of each size bin in fine particles, which meant that secondary pollution existed all year. Sulfates and nitrates, primarily in the form of (NH4)2SO4, NH4NO3, CaSO4, Na2SO4 and K2SO4, calculated by the model ISORROPIA II, were major components of the solid phase in fine particles. The PM concentration and size distribution were similar in the four seasons on non-haze days, while large differences occurred on haze days, which indicated seasonal variation of PM concentration and size distribution were dominated by haze days. The SIA concentrations and fractions of nearly all size bins were higher on haze days than on non-haze days, which was attributed to heterogeneous aqueous reactions on haze days in the four seasons. PMID:26040742

  4. Size-resolved aerosol water-soluble ionic compositions in the summer of Beijing: implication of regional secondary formation

    NASA Astrophysics Data System (ADS)

    Guo, S.; Hu, M.; Wang, Z. B.; Slanina, J.; Zhao, Y. L.

    2010-02-01

    To characterize aerosol pollution in Beijing, size-resolved aerosols were collected by MOUDIs during CAREBEIJING-2006 field campaign at Peking University (urban site) and Yufa (upwind rural site). Fine particle concentrations (PM1.8 by MOUDI) were 99.8±77.4 μg/m3 and 78.2±58.4 μg/m3, with PM1.8/PM10 ratios of 0.64±0.08 and 0.76±0.08 at PKU and Yufa, respectively, and secondary compounds accounted for more than 50% in fine particles. PMF model analysis was used to resolve the particle modes. Three modes were resolved at Yufa, representing condensation, droplet and coarse mode. However, one more droplet mode with bigger size was resolved, which was considered probably from regional transport. Condensation mode accounted for 10%-60% of the total mass at both sites, indicating that the gas-to-particle condensation process was important in summer. The formation of sulfate was mainly attributed to in-cloud or aerosol droplet process (PKU 80%, Yufa 70%) and gas condensation process (PKU 14%, Yufa 22%). According to the thermodynamic instability of NH4NO3, size distributions of nitrate were classified as three categories by RH. The existence of Ca(NO3)2 in droplet mode indicated the reaction of HNO3 with crustal particles was also important in fine particles. A rough estimation was given that 69% of the PM10 and 87% of the PM1.8 in Beijing urban were regional contributions. Sulfate, ammonium and oxalate were formed regionally, with the regional contributions of 90%, 87% and 95% to PM1.8. Nitrate formation was local dominant. In summary regional secondary formation led to aerosol pollution in the summer of Beijing.

  5. Size-resolved aerosol water-soluble ionic compositions in the summer of Beijing: implication of regional secondary formation

    NASA Astrophysics Data System (ADS)

    Guo, S.; Hu, M.; Wang, Z. B.; Slanina, J.; Zhao, Y. L.

    2009-11-01

    To characterize aerosol pollution in Beijing, size-resolved aerosols were collected by MOUDIs during CAREBEIJING-2006 field campaign at Peking University (urban site) and Yufa (upwind rural site). Fine particle concentrations (PM1.8 by MOUDI) were 99.8±77.4 μg/m3 and 78.2±58.4 μg/m3, with PM1.8/PM10 ratios of 0.64±0.08 and 0.76±0.08 at PKU and Yufa, respectively, and secondary compounds accounted for more than 50% in fine particles. PMF model was used to resolve the particle modes. Three modes were resolved at Yufa, representing condensation, droplet and coarse mode. However, one more droplet mode with bigger size was resolved, which was considered probably from regional transport. Condensation mode accounted for 10%-60% of the total mass at both sites, indicating it must be taken into account in summer. The formation of sulfate was mainly attributed to in-cloud or aerosol droplet process (PKU 80%, Yufa 70%) and gas condensation process (PKU 14%, Yufa 22%). According to the thermodynamic instability of NH4NO3, size distributions of nitrate were classified as three categories by RH. The existence of Ca(NO3)2 in droplet mode indicated the reaction of HNO3 with crustal particles was also important in fine particles. Linear regression gave a rough estimation that 69% of the PM10 and 87% of the PM1.8 at PKU were regional contributions. Sulfate, ammonium and oxalate were formed regionally, with the regional contributions of 90%, 87% and 95% to PM1.8. Nitrate formation was local dominant. In summary regional secondary formation led to aerosol pollution in the summer of Beijing.

  6. Development and validation of a size-resolved particle dry deposition scheme for application in aerosol transport models

    NASA Astrophysics Data System (ADS)

    Petroff, A.; Zhang, L.

    2010-12-01

    A size-resolved particle dry deposition scheme is developed for inclusion in large-scale air quality and climate models where the size distribution and fate of atmospheric aerosols is of concern. The "resistance" structure is similar to what is proposed by Zhang et al. (2001), while a new "surface" deposition velocity (or surface resistance) is derived by simplification of a one-dimensional aerosol transport model (Petroff et al., 2008b, 2009). Compared to Zhang et al.'s model, the present model accounts for the leaf size, shape and area index as well as the height of the vegetation canopy. Consequently, it is more sensitive to the change of land covers, particularly in the accumulation mode (0.1-1 micron). A drift velocity is included to account for the phoretic effects related to temperature and humidity gradients close to liquid and solid water surfaces. An extended comparison of this model with experimental evidence is performed over typical land covers such as bare ground, grass, coniferous forest, liquid and solid water surfaces and highlights its adequate prediction. The predictions of the present model differ from Zhang et al.'s model in the fine mode, where the latter tends to over-estimate in a significant way the particle deposition, as measured by various investigators or predicted by the present model. The present development is thought to be useful to modellers of the atmospheric aerosol who need an adequate parameterization of aerosol dry removal to the earth surface, described here by 26 land covers. An open source code is available in Fortran90.

  7. Functional characterization of the water-soluble organic carbon of size-fractionated aerosol in the southern Mississippi Valley

    NASA Astrophysics Data System (ADS)

    Chalbot, M.-C. G.; Brown, J.; Chitranshi, P.; Gamboa da Costa, G.; Pollock, E. D.; Kavouras, I. G.

    2014-06-01

    The chemical content of water-soluble organic carbon (WSOC) as a function of particle size was characterized in Little Rock, Arkansas in winter and spring 2013. The objectives of this study were to (i) compare the functional characteristics of coarse, fine and ultrafine WSOC and (ii) reconcile the sources of WSOC for periods when carbonaceous aerosol was the most abundant particulate component. The WSOC accounted for 5% of particle mass for particles with dp > 0.96 μm and 10% of particle mass for particles with dp < 0.96 μm. Non-exchangeable aliphatic (H-C), unsaturated aliphatic (H-C-C=), oxygenated saturated aliphatic (H-C-O), acetalic (O-CH-O) and aromatic (Ar-H) protons were determined by proton nuclear magnetic resonance (1H-NMR). The total non-exchangeable organic hydrogen concentrations varied from 4.1 ± 0.1 nmol m-3 for particles with 1.5 < dp < 3.0 μm to 73.9 ± 12.3 nmol m-3 for particles with dp < 0.49 μm. The molar H / C ratios varied from 0.48 ± 0.05 to 0.92 ± 0.09, which were comparable to those observed for combustion-related organic aerosol. The R-H was the most abundant group, representing about 45% of measured total non-exchangeable organic hydrogen concentrations, followed by H-C-O (27%) and H-C-C= (26%). Levoglucosan, amines, ammonium and methanesulfonate were identified in NMR fingerprints of fine particles. Sucrose, fructose, glucose, formate and acetate were associated with coarse particles. These qualitative differences of 1H-NMR profiles for different particle sizes indicated the possible contribution of biological aerosols and a mixture of aliphatic and oxygenated compounds from biomass burning and traffic exhausts. The concurrent presence of ammonium and amines also suggested the presence of ammonium/aminium nitrate and sulfate secondary aerosol. The size-dependent origin of WSOC was further corroborated by the increasing δ13C abundance from -26.81 ± 0.18‰ for the smallest particles to -25.93 ± 0.31‰ for the largest

  8. Functional characterization of the water-soluble organic carbon of size fractionated aerosol in the Southern Mississippi Valley

    NASA Astrophysics Data System (ADS)

    Chalbot, M.-C. G.; Brown, J.; Chitranshi, P.; Gamboa da Costa, G.; Pollock, E. D.; Kavouras, I. G.

    2014-02-01

    The chemical content of the water soluble organic carbon (WSOC) as a function of particle size was characterized in Little Rock, Arkansas in winter and spring 2013. The objectives of this study were to: (i) compare the functional characteristics of coarse, fine and ultrafine WSOC and (ii) reconcile the sources of WSOC for the period when carbonaceous aerosol was the most abundant particulate component. The WSOC accounted for 5% of particle mass for particles with dp > 0.96 μm and 10% of particle mass for particles with dp < 0.96 μm. Non-exchangeable aliphatic (H-C), unsaturated aliphatic (H-C-C=), oxygenated saturated aliphatic (H-C-O), acetalic (O-CH-O) and aromatic (Ar-H) protons were determined by proton nuclear magnetic resonance. The total non-exchangeable organic hydrogen concentrations varied from 4.1 ± 0.1 nmol m-3 for particles with 0.96 < dp < 1.5 μm to 73.9 ± 12.3 nmol m-3 for particles with dp < 0.49 μm, resulting in molar H / C ratios of 0.48 ± 0.05 to 0.92 ± 0.09 observed in combustion-related organic aerosol. The R-H was the most abundant group representing about 45% of measured total non-exchangeable organic hydrogen concentration followed by H-C-O (27%) and H-C-C= (26%). Levoglucosan, amines, ammonium and methanosulfonate were tentatively identified in NMR fingerprints of fine particles. Sucrose, fructose, glucose, formate and acetate were associated with coarse particles. These qualitative differences of 1H-NMR profiles for different particle sizes indicated the possible contribution of biological aerosol and a mixture of aliphatic and oxygenated compounds from biomass burning and traffic exhausts. The concurrent presence of ammonium and amines also suggested the presence of ammonium/aminium nitrate and sulfate secondary aerosol. The size-dependent origin of WSOC was further corroborated by the increasing δ13C abundance from -26.81 ± 0.18‰ for the smallest particles to -25.93 ± 0.31‰ for the largest particles and the relative

  9. Simultaneous retrieval of effective refractive index and density from size distribution and light-scattering data: weakly absorbing aerosol

    NASA Astrophysics Data System (ADS)

    Kassianov, E.; Barnard, J.; Pekour, M.; Berg, L. K.; Shilling, J.; Flynn, C.; Mei, F.; Jefferson, A.

    2014-10-01

    We propose here a novel approach for retrieving in parallel the effective density and real refractive index of weakly absorbing aerosol from optical and size distribution measurements. Here we define "weakly absorbing" as aerosol single-scattering albedos that exceed 0.95 at 0.5 μm. The required optical measurements are the scattering coefficient and the hemispheric backscatter fraction, obtained in this work from an integrating nephelometer. The required size spectra come from mobility and aerodynamic particle size spectrometers commonly referred to as a scanning mobility particle sizer and an aerodynamic particle sizer. The performance of this approach is first evaluated using a sensitivity study with synthetically generated but measurement-related inputs. The sensitivity study reveals that the proposed approach is robust to random noise; additionally the uncertainties of the retrieval are almost linearly proportional to the measurement errors, and these uncertainties are smaller for the real refractive index than for the effective density. Next, actual measurements are used to evaluate our approach. These measurements include the optical, microphysical, and chemical properties of weakly absorbing aerosol which are representative of a variety of coastal summertime conditions observed during the Two-Column Aerosol Project (TCAP; http://campaign.arm.gov/tcap/). The evaluation includes calculating the root mean square error (RMSE) between the aerosol characteristics retrieved by our approach, and the same quantities calculated using the conventional volume mixing rule for chemical constituents. For dry conditions (defined in this work as relative humidity less than 55%) and sub-micron particles, a very good (RMSE ~ 3%) and reasonable (RMSE ~ 28%) agreement is obtained for the retrieved real refractive index (1.49 ± 0.02) and effective density (1.68 ± 0.21), respectively. Our approach permits discrimination between the

  10. The impact of particle size, relative humidity, and sulfur dioxide on iron solubility in simulated atmospheric marine aerosols.

    PubMed

    Cartledge, Benton T; Marcotte, Aurelie R; Herckes, Pierre; Anbar, Ariel D; Majestic, Brian J

    2015-06-16

    Iron is a limiting nutrient in about half of the world's oceans, and its most significant source is atmospheric deposition. To understand the pathways of iron solubilization during atmospheric transport, we exposed size segregated simulated marine aerosols to 5 ppm sulfur dioxide at arid (23 ± 1% relative humidity, RH) and marine (98 ± 1% RH) conditions. Relative iron solubility increased as the particle size decreased for goethite and hematite, while for magnetite, the relative solubility was similar for all of the fine size fractions (2.5-0.25 μm) investigated but higher than the coarse size fraction (10-2.5 μm). Goethite and hematite showed increased solubility at arid RH, but no difference (p > 0.05) was observed between the two humidity levels for magnetite. There was no correlation between iron solubility and exposure to SO2 in any mineral for any size fraction. X-ray absorption near edge structure (XANES) measurements showed no change in iron speciation [Fe(II) and Fe(III)] in any minerals following SO2 exposure. SEM-EDS measurements of SO2-exposed goethite revealed small amounts of sulfur uptake on the samples; however, the incorporated sulfur did not affect iron solubility. Our results show that although sulfur is incorporated into particles via gas-phase processes, changes in iron solubility also depend on other species in the aerosol. PMID:26000788

  11. STUDY ON THE FEASIBILITY AND DESIGN OF AUTOMATIC PARTICULATE SIZE DISTRIBUTION ANALYZER FOR SOURCE EMISSIONS

    EPA Science Inventory

    The objective of this program was to evolve a method for the automatic determination of the size distribution of particulates within stack gas effluent streams. This device was designed to cover the typical mass concentration range encountered upstream as well as downstream of em...

  12. Aerosol number size distributions in the lower troposphere over a background region and megalopolis (Novosibirsk) on result of airborne sounding in 2011-2013

    NASA Astrophysics Data System (ADS)

    Belan, Boris D.; Kozlov, Artem V.; Simonenkov, Denis V.; Tolmachev, Gennadii N.; Tsaruk, Victoria V.

    2014-11-01

    In this paper we present a comparison of the data on aerosol number size distribution measured with GRIMM 1.109 aerosol spectrometer in the lower troposphere over Novosibirsk and background area 150 km south-west of it during research flights of Optik TU-134 aircraft laboratory carried out along the route Novosibirsk - Ordynskoye - Novosibirsk in 2011-2013. Aerosol number size distributions averaged over 3 years as together so for warm and cold seasons separately are considered here. It is shown that the accumulation of anthropogenic aerosol within the BL over the city is typical for the cold period, which is most likely caused by inversions those are rapidly destroyed by vertical mixing during warm season and anthropogenic aerosols from the city are transported into the free troposphere.

  13. Effect of the eruption of El Chichon stratospheric aerosol size and composition

    NASA Technical Reports Server (NTRS)

    Oberbeck, V. R.; Danielsen, E. F.; Snetsinger, K. G.; Ferry, G. V.; Fong, W.; Hayes, D. M.

    1983-01-01

    Dominant effects of the El Chichon eruption on stratospheric aerosols at 19.8 to 20.7 km are: (1) vapor depositional growth of the small-aerosol (background) mode; (2) development of a large-particle mode by sedimentation from the highest altitudes in the cloud; (3) a change in the large-particle mode from sulfate-coated silicates to sulfate aerosols, some with silicate cores; (4) a 100-fold increase in sulfate mass in the large particle mode. Terminal velocities of large silicate particles, maximum r = 2.3 micron, sampled 1 month after eruption, and calibrated with the aid of lidar data, indicate initial injection to 26 to 27 km. Smaller velocities of sulfate aerosols, median r = 0.5 micron, are compatible with major growth in 2 to 3 months at 27 to 28 km. Aerosol settling accounts for the descent of the main lidar return to 26.5 km in August and to 20 to 21 km in December.

  14. Surface Chemical Composition of Size-fractionated Urban Walkway Aerosols Determined by XPS and ToF-SIMS

    NASA Astrophysics Data System (ADS)

    Wenjuan, Cheng; Lu-Tao, Weng; Yongjie, Li; Arthur, Lau; Chak, Chan; Chi-Ming, Chan

    2013-04-01

    In this study, aerosol particles with sizes ranging from 0.056 to 10 ?m were collected using a ten-stage impactor sampler (MOUDI) from a busy walkway of Hong Kong. The aerosol samples of each stage were examined with X-ray photoelectron spectroscopy (XPS). Size dependent distributions of the detected six key elements (N, S, Ca, Si, O, and C) were revealed together with the chemical states of N, S and C. The results indicated that aliphatic hydrocarbons were the dominant species on the surface of all particles while a small portion of graphitic carbon (due to elemental and aromatic hydrocarbons) was also detected on the surface of the particles with sizes ranging from 0.056 to 0.32 ?m. Organic oxygen- and nitrogen-containing surface groups as well as sulfates were more abundant on the surface of the particles with sizes ranging from 0.32 to 1 μm. Organic oxygen- and nitrogen-containing surface groups as well as sulfates were more abundant on the surface of the particles with sizes ranging from 0.32 to 1 μm. Inorganic salts and nitrates were found in coarse-mode particles. Time-of-flight secondary ion mass spectrometry (ToF-SIMS) was used for detailed surface and near surface composition analysis. Principal component analysis (PCA) of the ToF-SIMS spectra confirmed the XPS results that aromatic hydrocarbons were associated with the nucleation-mode particles. Aliphatic hydrocarbons with O- and N-containing functional groups were associated with accumulation-mode particles and inorganic salts were related to the coarse-mode particles. Depth-profiling experiments were performed on three specific sets of samples (nucleation-, accumulation- and coarse-mode particles) to study their near-surface structures. It showed that organic compounds were concentrated on the very top surface of the coarse-mode particles with inorganics in the core. The accumulation-mode particles had thick coatings of diverse organic compositions. The nucleation-mode particles, which contained

  15. Water-soluble organic compounds in PM2.5 and size-segregated aerosols over Mount Tai in North China Plain

    NASA Astrophysics Data System (ADS)

    Wang, Gehui; Kawamura, Kimitaka; Umemoto, Nobuhiko; Xie, Mingjie; Hu, Shuyuan; Wang, Zifa

    2009-10-01

    Daytime and nighttime PM2.5 samples were collected at the summit of Mount Tai (1534 m) located in North China Plain during a week in 2006 summer. Size-segregated aerosol particles were also collected using an eight-stage impactor during the same period. Samples were analyzed for various water-soluble organic compounds using GC/FID and GC/MS techniques. Among the species identified in PM2.5 samples, dicarboxylic acids (C2-C11) were found as the most abundant compound class, followed by ketocarboxylic acids, saccharides, polyols and polyacids, and dicarbonyls. Daytime concentrations of most compounds were found to be 2-3 times higher than in nighttime. Such a diurnal variation was first interpreted by the depressed transport of pollutants in nighttime from the lowlands to the mountaintop owing to the decreased heights of planetary boundary layer, and second by the photochemical production in daytime. The diurnal variation trends of secondary organic aerosols (SOA) such as diacids at the mountain site are the same as those on lowlands, but the diurnal patterns of primary organic aerosols (POA) on the mountaintop are in contrast to those on lowlands, where POA such as saccharides and polyols are usually higher in nighttime owing to the accumulation within inversion layer developed. The eight-stage impactor samples showed bimodal distributions of diacids and related compounds peaking at size ranges of 0.70-1.1 μm and 5.8-9.0 μm. In the present study, water-soluble organics in the fine mode are largely originated from biomass burning and/or photooxidation of gaseous precursors and the subsequent adsorption on the preexisting particles, whereas those in the coarse mode are mainly derived from suspended soil particles and pollens and in part via the hygroscopic growth of fine particles and formation of cloud/fog droplets.

  16. A programmable palm-size gas analyzer for use in micro-autonomous systems

    NASA Astrophysics Data System (ADS)

    Gordenker, Robert J. M.; Wise, Kensall D.

    2012-06-01

    Gas analysis systems having small size, low power, and high selectivity are badly needed for defense (detection of explosives and chemical warfare agents), homeland security, health care, and environmental applications. This paper presents a palm-size gas chromatography system having analysis times of 5-50sec, detection limits less than 1ppb, and an average power dissipation less than one watt. It uses no consumables. The three-chip fluidic system consists of a preconcentrator, a 25cm-3m separation column, and a chemi-resistive detector and is supported by a microcomputer and circuitry for programmable temperature control. The entire system, including the mini-pump and battery, occupies less than 200cc and is configured for use on autonomous robotic vehicles.

  17. Phase/doppler spray analyzer for simultaneous measurements of drop size and velocity distributions

    NASA Technical Reports Server (NTRS)

    Bachalo, W. D.; Houser, M. J.

    1984-01-01

    Research was conducted on a laser light scatter detection method for measuring the size and velocity of spherical particles. The method is based upon the measurement of the interference fringe pattern produced by spheres passing through the intersection of two laser beams. A theoretical analysis of the method was carried out using the geometrical optics theory. The instrument response function was determined to be linear with drop size. Experimental verification of the theory was obtained by using monodisperse droplet streams. Several optical configurations were tested to identify all of the parametric effects upon the size measurements. Both off-axis forward-scatter and back-scatter light detection were utilized. Simulated spray environments and fuel spray nozzles were used in the evaluation of the method. The measurements of the monodisperse drops showed complete agreement with the theoretical predictions. The method was demonstrated to be independent of the beam intensity and extinction resulting from the surrounding drops. An instrument based on the concept has been developed.

  18. Zipf's Law Leads to Heaps' Law: Analyzing Their Relation in Finite-Size Systems

    PubMed Central

    Lü, Linyuan; Zhang, Zi-Ke; Zhou, Tao

    2010-01-01

    Background Zipf's law and Heaps' law are observed in disparate complex systems. Of particular interests, these two laws often appear together. Many theoretical models and analyses are performed to understand their co-occurrence in real systems, but it still lacks a clear picture about their relation. Methodology/Principal Findings We show that the Heaps' law can be considered as a derivative phenomenon if the system obeys the Zipf's law. Furthermore, we refine the known approximate solution of the Heaps' exponent provided the Zipf's exponent. We show that the approximate solution is indeed an asymptotic solution for infinite systems, while in the finite-size system the Heaps' exponent is sensitive to the system size. Extensive empirical analysis on tens of disparate systems demonstrates that our refined results can better capture the relation between the Zipf's and Heaps' exponents. Conclusions/Significance The present analysis provides a clear picture about the relation between the Zipf's law and Heaps' law without the help of any specific stochastic model, namely the Heaps' law is indeed a derivative phenomenon from the Zipf's law. The presented numerical method gives considerably better estimation of the Heaps' exponent given the Zipf's exponent and the system size. Our analysis provides some insights and implications of real complex systems. For example, one can naturally obtained a better explanation of the accelerated growth of scale-free networks. PMID:21152034

  19. Simultaneous forward- and backward-hemisphere elastic-light-scattering patterns of respirable-size aerosols

    NASA Astrophysics Data System (ADS)

    Fernandes, Gustavo E.; Pan, Yong-Le; Chang, Richard K.; Aptowicz, Kevin; Pinnick, Ronald G.

    2006-10-01

    Two-dimensional angular optical scattering (TAOS) patterns of aerosols are measured simultaneously from the forward hemisphere 15°<θ<90° as well as the backward hemisphere 90°<θ<165° (detecting 63% of the 4π sr of scattered light) by using an ellipsoidal reflector and an intensified CCD detector. TAOS patterns were obtained from polystyrene-latex spheres (individuals and aggregates) and from single Bacillus subtilis spores. These information-rich patterns, measured with a single laser pulse for individual particles on the fly, suggest that forward-TAOS and backward-TAOS measurements may be used for rapid classification of single aerosol particles.

  20. Evidence for a bimodal size distribution for the suspended aerosol particles on Mars

    NASA Astrophysics Data System (ADS)

    Fedorova, A. A.; Montmessin, F.; Rodin, A. V.; Korablev, O. I.; Määttänen, A.; Maltagliati, L.; Bertaux, J.-L.

    2014-03-01

    First simultaneous analysis of the ultraviolet (UV) and infrared (IR) atmospheric extinctions from SPICAM/Mars Express solar occultations in the beginning of the Northern summer (Ls = 56-97°) is presented. The two SPICAM channels allow sounding of the martian atmosphere in the spectral range from 0.118 to 1.7 μm at the altitudes from 10 to 80 km. Based on Mie scattering theory with adequate refraction indices for dust and H2O ice, a bimodal distribution of aerosol has been inferred from the SPICAM measurements. The coarser mode is represented by both dust and H2O particles with average radius of 0.7 and 1.2 μm, respectively, with number density from 0.01 to 10 particles in cm3. Clouds belonging to the aphelion cloud belt have been observed in midlatitudes in the Southern and the Northern hemispheres at altitudes of 20-30 km. The clouds are formed of large particles, and their opacity in the UV and the IR is below 0.03. The finer mode with a radius of 0.04-0.07 μm and a number density from 1 cm-3 at 60 km to 1000 cm-3 at 20 km has been detected in both hemispheres. In the Southern hemisphere the finer mode extends up to 70 km, whereas in the Northern hemisphere it is confined below 30-40 km. The lack of condensation nuclei is consistent, but could not fully explain the high water supersaturation observed between 30 and 50 km in the same Northern hemisphere dataset (Maltagliati L., Montmessin, F., Fedorova, A., Korablev, O., Forget, F., Bertaux, J.-L. [2011]. Science 333, 1868-1871). The average size of the fine mode (∼50 nm) and the large number density (up to 1000 cm-3) most likely corresponds to Aitken particles (r < 0.1 μm). This mode is unstable against coagulation and requires a continuous source of particles to be maintained, at least one order of magnitude more than estimations for the meteoric flux. A possible source is the dust lifting from the surface and dust devils. A detailed microphysical modeling is required to study the probability of survival

  1. Concentration, size-distribution and deposition of mineral aerosol over Chinese desert regions

    NASA Astrophysics Data System (ADS)

    Zhang, Xiao Y.; Arimoto, R.; Zhu, G. H.; Chen, T.; Zhang, G. Y.

    1998-09-01

    The mass-particle size distributions (MSDs) of 9 elements in ground-based aerosol samples from dust storm (DS) and non-dust storm (N-DS) periods were determined for 12 sites in 9 major desert regions in northern China. The masses of the 9 elements (Al, Fe, K, Mg, Mn, Sc, Si, Sr and Ti) in the atmosphere were dominated by local mineral dust that averaged 270μg m-3, and the MSDs for the elements were approximately log-normal. On the basis of Al data, the<10μm particles account for ~84% of the total dust mass over the deserts. Model-calculated ("100-step" method) dry deposition velocities (Vd) for the 9 dust-derived elements during N-DS periods ranged from 4.4 to 6.8cms-1, with a median value of 5.6cms-1. On the basis of a statistical relationship between D99% (the dust particle diameter corresponding to the uppermost 1% of the cumulative mass distribution) and Vd, one can also predict dry velocities, especially when D99% ranges from 30 to 70μm. This provides a simple way to reconstruct Vd for dust deposits (like aeolian loess sediments in the Loess Plateau). The estimated daily dry deposition fluxes were higher during DS vs. N-DS periods, but in most cases, the monthly averaged fluxes were mainly attributable to N-DS dust. Two regions with high dust loading and fluxes are identified: the "Western High-Dust Desert" and the "Northern High-Dust Desert", with Taklimakan Desert and Badain Juran Desert as their respective centers. These are energetic regions in which desert-air is actively exchanged, and these apparently are the major source areas for Asian dust.

  2. Aerosol in the Pacific troposphere

    NASA Technical Reports Server (NTRS)

    Clarke, Antony D.

    1989-01-01

    The use of near real-time optical techniques is emphasized for the measurement of mid-tropospheric aerosol over the Central Pacific. The primary focus is on measurement of the aerosol size distribution over the range of particle diameters from 0.15 to 5.0 microns that are essential for modeling CO2 backscatter values in support of the laser atmospheric wind sounder (LAWS) program. The measurement system employs a LAS-X (Laser Aerosol Spectrometer-PMS, Boulder, CO) with a custom 256 channel pulse height analyzer and software for detailed measurement and analysis of aerosol size distributions. A thermal preheater system (Thermo Optic Aerosol Descriminator (TOAD) conditions the aerosol in a manner that allows the discrimination of the size distribution of individual aerosol components such as sulfuric acid, sulfates and refractory species. This allows assessment of the relative contribution of each component to the BCO2 signal. This is necessary since the different components have different sources, exhibit independent variability and provide different BCO2 signals for a given mass and particle size. Field activities involve experiments designed to examine both temporal and spatial variability of these aerosol components from ground based and aircraft platforms.

  3. New image processing software for analyzing object size-frequency distributions, geometry, orientation, and spatial distribution

    NASA Astrophysics Data System (ADS)

    Beggan, Ciarán; Hamilton, Christopher W.

    2010-04-01

    Geological Image Analysis Software (GIAS) combines basic tools for calculating object area, abundance, radius, perimeter, eccentricity, orientation, and centroid location, with the first automated method for characterizing the aerial distribution of objects using sample-size-dependent nearest neighbor (NN) statistics. The NN analyses include tests for (1) Poisson, (2) Normalized Poisson, (3) Scavenged k=1, and (4) Scavenged k=2 NN distributions. GIAS is implemented in MATLAB with a Graphical User Interface (GUI) that is available as pre-parsed pseudocode for use with MATLAB, or as a stand-alone application that runs on Windows and Unix systems. GIAS can process raster data (e.g., satellite imagery, photomicrographs, etc.) and tables of object coordinates to characterize the size, geometry, orientation, and spatial organization of a wide range of geological features. This information expedites quantitative measurements of 2D object properties, provides criteria for validating the use of stereology to transform 2D object sections into 3D models, and establishes a standardized NN methodology that can be used to compare the results of different geospatial studies and identify objects using non-morphological parameters.

  4. PASSIVE AEROSOL SAMPLER FOR CHARACTERIZATION, AMBIENT CONCENTRATION, AND PARTICLE SIZE MEASUREMENT

    EPA Science Inventory

    This is an extended abstract of a presentation made at the Air and Waste Management Association's Symposium on Air Quality Measurement Methods and Technology, Durham, NC, May 9-11, 2006. The abstract describes the theory, design, and initial testing of a passive aerosol sampler f...

  5. AEROSOL CONCENTRATIONS DURING THE 1999 FRESNO EXPOSURE STUDIES AS FUNCTIONS OF SIZE, SEASON, AND METEOROLOGY

    EPA Science Inventory

    The 1999 Fresno exposure studies took place in February (winter season) and April/May (spring season) for two periods of four weeks. During that time, nearly-continuous measurements of outdoor aerosol concentrations were made with a scanning mobility spectrometer (TSI SNIPS) an...

  6. Mass size distributions of water-soluble inorganic and organic ions in size-segregated aerosols over metropolitan Newark in the US east coast

    NASA Astrophysics Data System (ADS)

    Zhao, Yunliang; Gao, Yuan

    2008-06-01

    To characterize the mass size distributions of water-soluble inorganic and organic ions associated with urban particulate matter, a total of 15 sets of size-segregated aerosol samples were collected by a 10-stage Micro-Orifice Uniform Deposit Impactor (MOUDI) in the urban area of Newark in New Jersey from July to December 2006. The mass concentrations of PM1.8 accounted for ∼68% of the mass concentrations of PM10. The mass concentrations of the total water-soluble ions in PM1.8 accounted for 31-81% of the mass concentrations of PM1.8. Sulfate was the dominant ion in fine particles, accounting for 31% of the PM1.8 mass with its dominant mode at 0.32-0.56 μm throughout all the samples. Nitrate size distributions were bi-modal, peaking at 0.32-0.56 and 3.2-5.6 μm, and the shift of the nitrate dominant fraction between fine and coarse modes was affected by temperature. The ratios of nitrate to PM1.8 varied significantly, 0.5-27%. The C2-C4 dicarboxylic acids accounted for 1.9±0.9% of PM1.8 mass, with oxalate being the dominant ion. The size distributions of oxalate exhibited two to four modes with the dominant one at 0.32-0.56 μm. Chloride existed in both coarse and fine modes, suggesting the influence of sea-salt aerosol and anthropogenic emissions. A crucial formation mechanism for the mass size distributions of these ions observed at this location is likely to be a combination of the gas-to-particle conversion and in-cloud/fog processing.

  7. The Different Faces of San Francisco's Ocean Beach: Analyzing Sand Size and Beach Shape

    NASA Astrophysics Data System (ADS)

    Grove, K.; Labit, R.; Lui, S.; Rodriquez, I.; Yi, C.; Yu, M.

    2004-12-01

    Ocean Beach is located along the western edge of San Francisco adjacent to the Pacific Ocean. Erosion along the southern part of the beach is threatening a nearby highway and water treatment plant. To better understand this beach and the processes that form it, our SF-ROCKS research group collected data from seven locations along its length. We used an auto-level surveying instrument to measure beach profiles and we collected sand samples that were measured using sieves and a sieve shaker. We plotted profiles and grain-size data using Excel and Surfer software. The sediment is mostly fine sand, and the means of all samples range between 0.19-0.26 mm. There may be little variation along the beach because only small sand grains have survived the long journey from their Sierra Nevada source. Profile shape does vary along the beach. The profile at the northern end is about three times wider than the profile at the southern end. The northern profile is flatter overall, but all profiles had a steep beach face in August, when the data were collected. The differences in beach profiles may be related to position relative to the offshore bar, which appears to provide sand to the northern part of the beach. Our group will collect more data in November to see what changes have occurred after the large-wave season has begun. We will use Surfer software to compare summer and fall profiles, to see where sediment has been added and where sediment has been removed. We will also compare our results to the data collected by Dr. Patrick Barnard and his research group at the U.S. Geological Survey, who are using an All-Terrain Vehicle to measure beach profiles and a camera to measure sediment size. We will use our analysis of beach variations to make recommendations for reducing beach erosion.

  8. Influence of inspiratory flow rate, particle size, and airway caliber on aerosolized drug delivery to the lung.

    PubMed

    Dolovich, M A

    2000-06-01

    A number of studies in the literature support the use of fine aerosols of drug, inhaled at low IFRs to target peripheral airways, with the objective of improving clinical responses to inhaled therapy (Fig. 8). Attempts have been made to separate response due to changes in total administered dose or the surface concentration of the dose from response due to changes in site of deposition--both are affected by the particle size of the aerosol, with IFR additionally influencing the latter. The tools for measuring dose and distribution have improved over the last 10-15 years, and thus we should expect greater accuracy in these measurements for assessing drug delivery to the lung. There are still issues, though, in producing radiolabeled (99m)technetium aerosols that are precise markers for the pharmaceutical product being tested and in quantitating absolute doses deposited in the lung. PET isotopes may provide the means for directly labelling a drug and perhaps can offer an alternative for making these measurements in the future, but deposition measurements should not be used in isolation; protocols should incorporate clinical tests to provide parallel therapeutic data in response to inhalation of the drug by the various patient populations being studied. PMID:10894453

  9. Size Resolved measurements of aerosol hygroscopicity and mixing state during Green Ocean Amazon (GoAmazon) 2014

    NASA Astrophysics Data System (ADS)

    Thalman, R. M.; Artaxo, P.; Campuzano Jost, P.; Barbosa, H. M.; Day, D. A.; de Sá, S. S.; Hu, W.; Jimenez, J. L.; Kuang, C.; Palm, B. B.; Krüger, M. L.; Manzi, A. O.; Martin, S. T.; Poeschl, U.; Sedlacek, A. J., III; Senum, G.; Souza, R. A. F. D.; Springston, S. R.; Alexander, M. L.; Watson, T. B.; Wang, J.

    2014-12-01

    Measurements of size-resolved cloud condensation nucleai (CCN) spectra were performed at the T3 site of the Green Ocean Amazon (GoAmazon) field project located near Manacapuru, Brazil during 2014. The T3 site is a receptor site for both polluted urban down-wind (Manaus, BR a city of several million 70 km up wind) and background (Amazon rainforest) air-masses and can provide a contrast between clean and polluted conditions. Particle hygroscopicity (kappa) and mixing state were calculated from the particle activation spectrum measured by size selecting aerosols and exposing them to a wide range of supersaturation in the CCN counter (Droplet Measurement Technologies Continuous-Flow Streamwise Thermal Gradient CCN Chamber). The supersaturation was varied between 0.07 and 1.1% by changing a combination of both total flow rate and temperature gradient in the CCN counter. Measured spectra were examined for air masses with different level of influence from Manaus plume. Particle hygroscopicity generally peaked near noon local time which was broadly consistent with the trend in aerosol sulfate. The average kappa values during the first intensive operation period were 0.14±0.05, 0.14±0.04 and 0.16±0.06 for 75, 112 and 171 nm particles respectively. Evaluation of particle hygroscopicity and dispersion (mixing state) will be presented with respect to size and level of pollution.

  10. Analyzing Particle Size Effects in ZnS:Cu using X-ray Absorption Spectroscopy

    NASA Astrophysics Data System (ADS)

    Medling, Scott; Kozina, M.; Jiang, Y.; Balaban, B.; Bridges, F.; Carter, S.

    2009-11-01

    We report XAS measurements on ZnS:Cu,Mn phosphor materials of various particle sizes, 1-25μm. These materials exhibit electroluminescence (EL) at AC voltages of order 100V for ˜25μm particles, but only from small points associated with CuS nanoprecipitates (which form along the 111 plane in ZnS); here the local electric fields are enhanced by a factor of about 100. To enable lower-voltage applications, it is desirable to make smaller particles so devices can be thinner. We investigated the local structure for smaller particles produced by mill-grinding to determine why grinding leads to reduced AC EL. The K-edge EXAFS data show a decreased Cu-S first peak amplitude for the ground particle samples, but little change for Mn-S or Zn-S peaks. The XANES data show a large change in the structure of the Cu K-edge for smaller particles but not for either the host Zn or Mn dopant edges. Clearly grinding affects the environment about Cu, in the CuS precipitates, much more than the ZnS host lattice. Possibly the ZnS particles fracture preferentially through the CuS precipitates or the ZnS particles are partially sheared along the 111 plane.

  11. Long-term observations of aerosol size distributions in semi-clean and polluted savannah in South Africa

    NASA Astrophysics Data System (ADS)

    Vakkari, V.; Beukes, J. P.; Laakso, H.; Mabaso, D.; Pienaar, J. J.; Kulmala, M.; Laakso, L.

    2012-09-01

    This study presents a total of four years of sub-micron aerosol particle size distribution measurements in the Southern African savannah, an environment with few previous observations covering a full seasonal cycle and the size range below 100 nm. During the first 19 months, July 2006-January 2008, the measurements were carried out at Botsalano, a semi-clean location, whereas during the latter part, February 2008-May 2010, the measurements were carried out at Marikana (approximately 150 km east of Botsalano), which is a more polluted location with both pyrometallurgical industries and informal settlements nearby. The median total concentration of aerosol particles was more than four times as high at Marikana than at Botsalano. In the size ranges of 12-840 nm, 50-840 nm and 100-840 nm the median concentrations were 1850, 1280 and 700 particles cm-3 at Botsalano and 7800, 3800 and 1600 particles cm-3 at Marikana, respectively. The diurnal variation of the size distribution for Botsalano arose as a result of frequent regional new particle formation. However, for Marikana the diurnal variation was dominated by the morning and evening household burning in the informal settlements, although regional new particle formation was even more frequent than at Botsalano. The effect of the industrial emissions was not discernible in the size distribution at Marikana although it was clear in the sulphur dioxide diurnal pattern, indicating the emissions to be mostly gaseous. Seasonal variation was strongest in the concentration of particles larger than 100 nm, which was clearly elevated at both locations during the dry season from May to September. In the absence of wet removal during the dry season the concentration of particles larger than 100 nm had a correlation above 0.7 with CO for both locations, which implies incomplete burning to be an important source of aerosol particles during the dry season. However, the sources of burning differ: at Botsalano the rise in concentration

  12. Long-term observations of aerosol size distributions in semi-clean and polluted savannah in South Africa

    NASA Astrophysics Data System (ADS)

    Vakkari, V.; Beukes, J. P.; Laakso, H.; Mabaso, D.; Pienaar, J. J.; Kulmala, M.; Laakso, L.

    2013-02-01

    This study presents a total of four years of sub-micron aerosol particle size distribution measurements in the southern African savannah, an environment with few previous observations covering a full seasonal cycle and the size range below 100 nm. During the first 19 months, July 2006-January 2008, the measurements were carried out at Botsalano, a semi-clean location, whereas during the latter part, February 2008-May 2010, the measurements were carried out at Marikana (approximately 150 km east of Botsalano), which is a more polluted location with both pyrometallurgical industries and informal settlements nearby. The median total concentration of aerosol particles was more than four times as high at Marikana than at Botsalano. In the size ranges of 12-840 nm, 50-840 nm and 100-840 nm the median concentrations were 1856, 1278 and 698 particles cm-3 at Botsalano and 7805, 3843 and 1634 particles cm-3 at Marikana, respectively. The diurnal variation of the size distribution for Botsalano arose as a result of frequent regional new particle formation. However, for Marikana the diurnal variation was dominated by the morning and evening household burning in the informal settlements, although regional new particle formation was even more frequent than at Botsalano. The effect of the industrial emissions was not discernible in the size distribution at Marikana although it was clear in the sulphur dioxide diurnal pattern, indicating the emissions to be mostly gaseous. Seasonal variation was strongest in the concentration of particles larger than 100 nm, which was clearly elevated at both locations during the dry season from May to September. In the absence of wet removal during the dry season, the concentration of particles larger than 100 nm had a correlation above 0.7 with CO for both locations, which implies incomplete burning to be an important source of aerosol particles during the dry season. However, the sources of burning differ: at Botsalano the rise in

  13. Production Mechanisms, Number Concentration, Size Distribution. Chemical Composition, and Optical Properties of Sea Spray Aerosols

    NASA Technical Reports Server (NTRS)

    Meskhidze, Nicholas; Petters, Markus; Tsigaridis, Kostas; Bates. Tim; O'Dowd, Colin; Reid, Jeff; Lewis, Ernie R.; Gantt, Brett; Anguelova, Magdalena D.; Bhave, Prakash V.; Bird, James; Callaghan, Adrian H.; Ceburnis, Darius; Chang, Rachel; Clark, Antony; deLeeuw, Gerrit; Deane, Grant; DeMott, Paul J.; Elliot, Scott; Facchini, Maria Cristina; Fairall, Chris W.; Hawkins, Lelia; Hu, Yongxiang; Smirnov, Alexander

    2013-01-01

    Over forty scientists from six countries convened in Raleigh, NC on June 4-6 2012 to review the status and prospects of sea spray aerosol research. Participants were researchers from the oceanography and atmospheric science communities, including academia, private industry, and government agencies. The recommendations from the working groups are summarized in a science prioritization matrix that is meant to prioritize the research agenda and identify areas of investigation by the magnitude of their impact on proposed science questions. Str

  14. AGLITE: a multiwavelength lidar for aerosol size distributions, flux, and concentrations

    NASA Astrophysics Data System (ADS)

    Wilkerson, Thomas D.; Zavyalov, Vladimir V.; Bingham, Gail E.; Swasey, Jason A.; Hancock, Jed J.; Crowther, Blake G.; Cornelsen, Scott S.; Marchant, Christian; Cutts, James N.; Huish, David C.; Earl, Curtis L.; Andersen, Jan M.; Cox, McLain L.

    2006-05-01

    We report on the design, construction and operation of a new multiwavelength lidar developed for the Agricultural Research Service of the United States Department of Agriculture and its program on particle emissions from animal production facilities. The lidar incorporates a laser emitting simultaneous, pulsed Nd laser radiation at 355, 532 and 1064 nm at a PRF of 10 kHz. Lidar backscatter and extinction data are modeled to extract the aerosol information. All-reflective optics combined with dichroic and interferometric filters permit all the wavelength channels to be measured simultaneously, day or night, using photon counting by PMTs, an APD, and high speed scaling. The lidar is housed in a transportable trailer for all-weather operation at any accessible site. The laser beams are directed in both azimuth and elevation to targets of interest. We describe application of the lidar in a multidisciplinary atmospheric study at a swine production farm in Iowa. Aerosol plumes emitted from the hog barns were prominent phenomena, and their variations with temperature, turbulence, stability and feed cycle were studied, using arrays of particle samplers and turbulence detectors. Other lidar measurements focused on air motion as seen by long duration scans of the farm region. Successful operation of this lidar confirms the value of multiwavelength, eye-safe lidars for agricultural aerosol measurements.

  15. Deriving aerosol hygroscopic mixing state from size-resolved CCN activity and HR-ToF-AMS measurements

    NASA Astrophysics Data System (ADS)

    Bhattu, Deepika; Tripathi, S. N.; Chakraborty, Abhishek

    2016-10-01

    The ability of a particle to uptake water and form a cloud droplet depends on its hygroscopicity. To understand its impact on cloud properties and ultimately radiative forcing, knowledge of chemically-resolved mixing state information or the one based on hygroscopic growth is crucial. Typically, global models assume either pure internal or external mixing state which might not be true for all conditions and sampling locations. To investigate into this, the current study employed an indirect approach to infer the probable mixing state. The hygroscopic parameters derived from κ-Kohler theory using size-resolved CCN measurements (κCCN) and bulk/size-resolved aerosol mass spectrometer (AMS) measurements (κAMS) were compared. The accumulation mode particles were found to be more hygroscopic (κCCN = 0.24) than Aitken mode (κCCN = 0.13), perhaps due to increased ratio of inorganic to organic mass fraction. The activation diameter calculated from size-resolved CCN activity measurements at 5 different supersaturation (SS) levels varied in the range of 115 nm-42 nm with κCCN = 0.13-0.23 (avg = 0.18 ± 0.10 (±1σ)). Further, κAMS>κCCN was observed possibly due to the fact that organic and inorganic mass present in the Aitken mode was not correctly represented by bulk chemical composition and size-resolved fractional contribution of oxidized OA was not accurately accounted. Better correlation of organic fraction (forg) and κCCN at lower SS explained this behaviour. The decrease in κCCN with the time of the day was more pronounced at lower SS because of the relative mass reduction of soluble inorganic species by ∼17%. Despite the large differences between κ measured from two approaches, less over-prediction (up to 18%) between measured and predicted CCN concentration suggested lower impact of chemical composition and mixing state at higher SS. However, at lower SS, presences of externally mixed CCN-inactive aerosols lead to CCN over-prediction reflecting the

  16. On the Aerosol Particle Size Distribution Spectrum in Alaskan Air Mass Systems: Arctic Haze and Non-Haze Episodes.

    NASA Astrophysics Data System (ADS)

    Shaw, Glenn E.

    1983-05-01

    Aerosols in central Alaskan winter air mass system were classified according to size by diffusive separation and light-scattering spectrometry. Particles entering central Alaska from the Pacific Marine environment had number concentrations ranging from 300 to 2000 cm3 (geometric mean 685 cm3) and unimodal size spectra, with maximum in number concentration near 1 × 106 cm radius.Air masses entering Alaska from the Eurasian Arctic possessed a factor of two smaller aerosol number concentrations than Pacific Marine systems (e.g., 150-700 cm3; geometric mean 386 cm3) but contained a factor of two greater particle volume loading within the fine particle radius range 5 × 107 < r < 1 × 105 cm. The particles in Eurasian Arctic air masses were bimodally distributed, with maxima in the particle size spectra near r = 3 × 107 and 5 × 106 cm. Sulfur was the predominant element in all cases studied.A particle depleted region was present in the size spectra obtained for Eurasian Arctic air masses. The deficiency of particles in the 106 cm radius range is interpreted as being the result of thermal coagulation taking place between sulfur-rich nuclei (produced at a rate of 1020 to 1018 g cm3 s1 and in sizes r < 106 cm) and `large' (r 105 cm) imported primary particles. The primary particles are in the removal-resistant Greenfield Gap (r 105 cm) and seem to originate in the central Eurasian region.

  17. Size distribution and optical properties of mineral dust aerosols transported in the western Mediterranean

    NASA Astrophysics Data System (ADS)

    Denjean, C.; Cassola, F.; Mazzino, A.; Triquet, S.; Chevaillier, S.; Grand, N.; Bourrianne, T.; Momboisse, G.; Sellegri, K.; Schwarzenbock, A.; Freney, E.; Mallet, M.; Formenti, P.

    2016-02-01

    This study presents in situ aircraft measurements of Saharan mineral dust transported over the western Mediterranean basin in June-July 2013 during the ChArMEx/ADRIMED (the Chemistry-Aerosol Mediterranean Experiment/Aerosol Direct Radiative Impact on the regional climate in the MEDiterranean region) airborne campaign. Dust events differing in terms of source region (Algeria, Tunisia and Morocco), time of transport (1-5 days) and height of transport were sampled. Mineral dust were transported above the marine boundary layer, which conversely was dominated by pollution and marine aerosols. The dust vertical structure was extremely variable and characterized by either a single layer or a more complex and stratified structure with layers originating from different source regions. Mixing of mineral dust with pollution particles was observed depending on the height of transport of the dust layers. Dust layers carried a higher concentration of pollution particles below 3 km above sea level (a.s.l.) than above 3 km a.s.l., resulting in a scattering Ångström exponent up to 2.2 below 3 km a.s.l. However, the optical properties of the dust plumes remained practically unchanged with respect to values previously measured over source regions, regardless of the altitude. Moderate absorption of light by the dust plumes was observed with values of aerosol single scattering albedo at 530 nm ranging from 0.90 to 1.00. Concurrent calculations from the aerosol chemical composition revealed a negligible contribution of pollution particles to the absorption properties of the dust plumes that was due to a low contribution of refractory black carbon in regards to the fraction of dust and sulfate particles. This suggests that, even in the presence of moderate pollution, likely a persistent feature in the Mediterranean, the optical properties of the dust plumes could be assumed similar to those of native dust in radiative transfer simulations, modelling studies and satellite retrievals

  18. Size distribution and optical properties of mineral dust aerosols transported in the western Mediterranean

    NASA Astrophysics Data System (ADS)

    Denjean, C.; Cassola, F.; Mazzino, A.; Triquet, S.; Chevaillier, S.; Grand, N.; Bourrianne, T.; Momboisse, G.; Sellegri, K.; Schwarzenbock, A.; Freney, E.; Mallet, M.; Formenti, P.

    2015-08-01

    This study presents in situ aircraft measurements of Saharan mineral dust transported over the western Mediterranean basin in June-July 2013 during the ChArMEx/ADRIMED (the Chemistry-Aerosol Mediterranean Experiment/Aerosol Direct Radiative Impact on the regional climate in the MEDiterranean region) airborne campaign. Dust events differing in terms of source region (Algeria, Tunisia and Morocco), time of tranport (1-5 days) and height of transport were sampled. Mineral dust were transported above the marine boundary layer, which conversely was dominated by pollution and marine aerosols. The dust vertical structure was extremely variable and characterized by either a single layer or a more complex and stratified structure with layers originating from different source regions. Mixing of mineral dust with pollution particles was observed depending on the height of transport of the dust layers. Dust layers carried higher concentration of pollution particles at intermediate altitude (1-3 km) than at elevated altitude (> 3 km), resulting in scattering Angstrom exponent up to 2.2 within the intermediate altitude. However, the optical properties of the dust plumes remained practically unchanged with respect to values previously measured over source regions, regardless of the altitude. Moderate light absorption of the dust plumes was observed with values of aerosol single scattering albedo at 530 nm ranging from 0.90 to 1.00 ± 0.04. Concurrent calculations from the aerosol chemical composition revealed a negligible contribution of pollution particles to the absorption properties of the dust plumes that was due to a low contribution of refractory black carbon in regards to the fraction of dust and sulfate particles. This suggests that, even in the presence of moderate pollution, likely a persistent feature in the Mediterranean, the optical properties of the dust plumes could be assimilated to those of native dust in radiative transfer simulations, modeling studies and

  19. Chemical characteristics of size-resolved aerosols from Asian dust and haze episode in Seoul Metropolitan City

    NASA Astrophysics Data System (ADS)

    Kang, Eunha; Han, Jihyun; Lee, Meehye; Lee, Gangwoong; Kim, Jong Chun

    2013-06-01

    We collected aerosol particles in Seoul using a 10 stage Micro-Orifice Uniform Deposit Impactor (MOUDI) to investigate the size distributions of aerosol mass and water-soluble inorganic ions (Na+, NH4+, K+, Mg2 +, Ca2 +, Cl-, NO3-, and SO42 -) for the two high-mass episodes taking place in February and April, 2009. The former was a heavy Asian dust (AD) event and the latter was a haze episode associated with stagnant condition that prevailed over the Yellow Sea region. In AD plume, the mass peak was noticeable at coarse mode between 1.0 and 1.8 μm but SO42 - and NH4+ were enriched in condensation mode between 0.056 and 0.1 μm. There was little chance for the heavy AD plume to pick up SO2 and water vapor, which are in good accordance with its transport paths and the chemical characteristics of aerosols and gaseous species. These results imply that the heterogeneous reaction of SO2 on dust particles would not be substantial in determining sulfate concentrations for this particular type of dust plume, considering the possibility of loss of large soil particles in MOUDI. During the haze episode, both total aerosol mass and water-soluble inorganic ions showed bimodal size distributions with the droplet (0.32-0.56 μm) and coarse (1.0-1.8 μm) mode peaks. In this haze event, acidic gases tend to be dissolved more efficiently in larger particles, shifting the peaks of SO42 - and NO3- to larger droplet particles. For NH4+, however, the mode change was not observed, which was probably due to the depleted source and high solubility of NH3. These results demonstrated that the availability of precursor gases such as SO2, NO2, and NH3, and the water-vapor contents were important factor to determine the formation of droplet-mode particles and their sizes.

  20. Impacts of Venturi Turbulent Mixing on the Size Distributions of Sodium Chloride and Dioctyl-Phthalate Aerosols

    SciTech Connect

    Cheng, M-D.

    2000-08-23

    Internal combustion engines are a major source of airborne particulate matter (PM). The size of the engine PM is in the sub-micrometer range. The number of engine particles per unit volume is high, normally in the range of 10{sup 12} to 10{sup 14}. To measure the size distribution of the engine particles dilution of an aerosol sample is required. A diluter utilizing a venturi ejector mixing technique is commercially available and tested. The purpose of this investigation was to determine if turbulence created by the ejector in the mini-dilutor changes the size of particles passing through it. The results of the NaCl aerosol experiments show no discernible difference in the geometric mean diameter and geometric standard deviation of particles passing through the ejector. Similar results were found for the DOP particles. The ratio of the total number concentrations before and after the ejector indicates that a dilution ratio of approximately 20 applies equally for DOP and NaCl particles. This indicates the dilution capability of the ejector is not affected by the particle composition. The statistical analysis results of the first and second moments of a distribution indicate that the ejector may not change the major parameters (e.g., the geometric mean diameter and geometric standard deviation) characterizing the size distributions of NaCl and DOP particles. However, when the skewness was examined, it indicates that the ejector modifies the particle size distribution significantly. The ejector could change the skewness of the distribution in an unpredictable and inconsistent manner. Furthermore, when the variability of particle counts in individual size ranges as a result of the ejector is examined, one finds that the variability is greater for DOP particles in the size range of 40-150 nm than for NaCl particles in the size range of 30 to 350 nm. The numbers or particle counts in this size region are high enough that the Poisson counting errors are small (<10

  1. The mathematical principles and design of the NAIS - a spectrometer for the measurement of cluster ion and nanometer aerosol size distributions

    NASA Astrophysics Data System (ADS)

    Mirme, S.; Mirme, A.

    2013-04-01

    The paper describes the Neutral cluster and Air Ion Spectrometer (NAIS) - a multichannel aerosol instrument capable of measuring the distribution of ions (charged particles and cluster ions) of both polarities in the electric mobility range from 3.2 to 0.0013 cm2 V-1 s-1 and the distribution of aerosol particles in the size range from 2.0 to 40 nm. We introduce the principles of design, data processing and spectrum deconvolution of the instrument.

  2. Deposition and clearance of monodisperse aerosols in the calf lung: effects of particle size and a mucolytic agent (bromhexine)

    PubMed Central

    Davies, C P; Webster, A J

    1987-01-01

    Mucociliary clearance and retention of monodisperse aerosols of radiolabelled polystyrene particles of both 3.3 microns and 5 microns diameter were investigated in four healthy calves and two sick calves. The effect of the mucolytic agent bromhexine was also assessed at two dosage levels. There were significant differences (P less than 0.05) in clearance rate constant between calves, but similar patterns of clearance for each calf. These characteristics of mechanical lung clearance did not vary over a two month period. Values of clearance rate constant and percentage retention varied significantly (P less than 0.001) between the two different particle sizes, 5 microns particles giving faster clearance and lower retention of particles than 3.3 microns particles. Bromhexine at the recommended dose of 1.6 mg/kg 0.75 caused a significant (P less than 0.05) increase in clearance rate in both healthy and sick calves, but affected percentage retention only in sick calves. This study illustrates the variation in mucociliary clearance rates shown by individuals and also underlines the importance of particle size in aerosols used for studies of pulmonary deposition and clearance. The work also indicates that bromhexine may be of use in the therapy of respiratory disease in calves. PMID:3651885

  3. Deposition and clearance of monodisperse aerosols in the calf lung: effects of particle size and a mucolytic agent (bromhexine)

    PubMed

    Davies, C P; Webster, A J

    1987-07-01

    Mucociliary clearance and retention of monodisperse aerosols of radiolabelled polystyrene particles of both 3.3 microns and 5 microns diameter were investigated in four healthy calves and two sick calves. The effect of the mucolytic agent bromhexine was also assessed at two dosage levels. There were significant differences (P less than 0.05) in clearance rate constant between calves, but similar patterns of clearance for each calf. These characteristics of mechanical lung clearance did not vary over a two month period. Values of clearance rate constant and percentage retention varied significantly (P less than 0.001) between the two different particle sizes, 5 microns particles giving faster clearance and lower retention of particles than 3.3 microns particles. Bromhexine at the recommended dose of 1.6 mg/kg 0.75 caused a significant (P less than 0.05) increase in clearance rate in both healthy and sick calves, but affected percentage retention only in sick calves. This study illustrates the variation in mucociliary clearance rates shown by individuals and also underlines the importance of particle size in aerosols used for studies of pulmonary deposition and clearance. The work also indicates that bromhexine may be of use in the therapy of respiratory disease in calves. PMID:3651885

  4. Analyzing the efficiency of small and medium-sized enterprises of a national technology innovation research and development program.

    PubMed

    Park, Sungmin

    2014-01-01

    This study analyzes the efficiency of small and medium-sized enterprises (SMEs) of a national technology innovation research and development (R&D) program. In particular, an empirical analysis is presented that aims to answer the following question: "Is there a difference in the efficiency between R&D collaboration types and between government R&D subsidy sizes?" Methodologically, the efficiency of a government-sponsored R&D project (i.e., GSP) is measured by Data Envelopment Analysis (DEA), and a nonparametric analysis of variance method, the Kruskal-Wallis (KW) test is adopted to see if the efficiency differences between R&D collaboration types and between government R&D subsidy sizes are statistically significant. This study's major findings are as follows. First, contrary to our hypothesis, when we controlled the influence of government R&D subsidy size, there was no statistically significant difference in the efficiency between R&D collaboration types. However, the R&D collaboration type, "SME-University-Laboratory" Joint-Venture was superior to the others, achieving the largest median and the smallest interquartile range of DEA efficiency scores. Second, the differences in the efficiency were statistically significant between government R&D subsidy sizes, and the phenomenon of diseconomies of scale was identified on the whole. As the government R&D subsidy size increases, the central measures of DEA efficiency scores were reduced, but the dispersion measures rather tended to get larger. PMID:25120949

  5. Functional characterization of the water-soluble organic carbon of size-fractionated aerosol in the southern Mississippi Valley

    PubMed Central

    Chalbot, M.-C. G.; Brown, J.; Chitranshi, P.; da Costa, G. Gamboa; Pollock, E. D.; Kavouras, I. G.

    2016-01-01

    The chemical content of water-soluble organic carbon (WSOC) as a function of particle size was characterized in Little Rock, Arkansas in winter and spring 2013. The objectives of this study were to (i) compare the functional characteristics of coarse, fine and ultrafine WSOC and (ii) reconcile the sources of WSOC for periods when carbonaceous aerosol was the most abundant particulate component. The WSOC accounted for 5 % of particle mass for particles with δp > 0.96 μm and 10 % of particle mass for particles with δp < 0.96 μm. Non-exchangeable aliphatic (H–C), unsaturated aliphatic (H–C–C=), oxygenated saturated aliphatic (H–C–O), acetalic (O–CH–O) and aromatic (Ar–H) protons were determined by proton nuclear magnetic resonance (1H-NMR). The total non-exchangeable organic hydrogen concentrations varied from 4.1 ± 0.1 nmol m−3 for particles with 1.5 < δp < 3.0 μm to 73.9 ± 12.3 nmol m−3 for particles with δp < 0.49 μm. The molar H/C ratios varied from 0.48 ± 0.05 to 0.92 ± 0.09, which were comparable to those observed for combustion-related organic aerosol. The R–H was the most abundant group, representing about 45 % of measured total non-exchangeable organic hydrogen concentrations, followed by H–C–O (27 %) and H–C–C= (26 %). Levoglucosan, amines, ammonium and methanesulfonate were identified in NMR fingerprints of fine particles. Sucrose, fructose, glucose, formate and acetate were associated with coarse particles. These qualitative differences of 1H-NMR profiles for different particle sizes indicated the possible contribution of biological aerosols and a mixture of aliphatic and oxygenated compounds from biomass burning and traffic exhausts. The concurrent presence of ammonium and amines also suggested the presence of ammonium/aminium nitrate and sulfate secondary aerosol. The size-dependent origin of WSOC was further corroborated by the increasing δ13C abundance from −26.81 ± 0.18 ‰ for the smallest particles to

  6. Performance of the Phase Doppler Particle Analyzer icing cloud droplet sizing probe in the NASA Lewis Icing Research Tunnel

    NASA Technical Reports Server (NTRS)

    Rudoff, R. C.; Bachalo, E. J.; Bachalo, W. D.; Oldenburg, J. R.

    1992-01-01

    The design, development, and testing of an icing cloud droplet sizing probe based upon the Phase Doppler Particle Analyzer (PDPA) are discussed. This probe is an in-situ laser interferometry based single particle measuring device capable of determining size distributions. The probe is designed for use in harsh environments such as icing tunnels and natural icing clouds. From the measured size distribution, Median Volume Diameter (MVD) and Liquid Water Content (LWC) may be determined. Both the theory of measurement and the mechanical aspects of the probe design and development are discussed. The MVD results from the probe are compared to an existing calibration based upon different instruments in a series of tests in the NASA Lewis Icing Research Tunnel. Agreement between the PDPA probe and the existing calibration is close for MVDs between 15 to 30 microns, but the PDPA results are considerably smaller for MVDs under 15 microns.

  7. Ultrafine aerosol size distributions and sulfuric acid vapor pressures: Implications for new particle formation in the atmosphere. Year 2 progress report

    SciTech Connect

    McMurry, P.H.

    1993-07-01

    This project has two components: (1) measurement of H{sub 2}SO{sub 4} vapor pressures in air under temperature/relative humidity conditions similar to atmospheric, and (2) measurement of ultrafine aerosol size distributions. During Year 2, more effort was put on size distribution measurements. 4 figs.

  8. Martian Dust Aerosol Size and Shape as Constrained by Phoenix Lander Polarimetry

    NASA Astrophysics Data System (ADS)

    Lemmon, Mark T.; Mason, Emily L.

    2014-11-01

    Dust aerosol morphology is important to dust transport and the radiative heating of the Martian atmosphere. Previous analyses of Mars dust have shown that spherical particles are a bad analog for the dust, in terms of reproducing the distribution of scattered light. Parameterized scattering, based on laboratory observations of scattering by irregular dust particles, has been used for Viking, Pathfinder and Mars Exploration Rover data [Pollack et al., J. Geophys. Res. 100, 1995; Tomasko et al., J. Geophys. Res. 104, 1999; Lemmon et al., Science 306, 2004]. Analytical calculations have shown that cylinders are a better scattering analog than spheres [Wolff et al., J. Geophys. Res. 114, 2009]. Terrestrial studies have shown that a diverse assortment of triaxial ellipsoids is a good analog for dust aerosol [Bi et al., Applied Optics 48, 2009].The Phoenix Lander operated in the Martian arctic for 5 months of 2008, around the northern summer solstice. During the mission atmospheric optical depth was tracked through direct solar imaging by the Surface Stereo Imager (SSI). For solar longitude (Ls) 78-95 and 140-149, small dust storms dominated the weather. Low-dust conditions (optical depths <0.4) dominated during Ls 95-140, with sporadic ice clouds becoming more common after Ls 108. The SSI also obtained occasional cross-sky photometric data through several filters from 440 to 1000 nm and cross-sky polarimetry at 750 nm wavelength. Radiative transfer models of the sky radiance distribution are consistent with dust aerosols in the same 1.3-1.6 micron range reported for models of observations from previous missions. Cylinders, triaxial ellipsoids, and the parametric model can fit sky radiances; spheres cannot. The observed linear polarization, which reached 4-5% and had a similar angular distribution to Rayleigh polarization, is similar to the triaxial ellipsoid model, but not spheres or cylinders. An extension to the parametric model using 7-10% Rayleigh scattering mixed

  9. The effect of local sources on particle size and chemical composition and their role in aerosol-cloud interactions at Puijo measurement station

    NASA Astrophysics Data System (ADS)

    Portin, H.; Leskinen, A.; Hao, L.; Kortelainen, A.; Miettinen, P.; Jaatinen, A.; Laaksonen, A.; Lehtinen, K. E. J.; Romakkaniemi, S.; Komppula, M.

    2014-06-01

    Interactions between aerosols and liquid water clouds were studied during autumns 2010-2011 at a semiurban measurement station on Puijo tower in Kuopio, Finland. Cloud interstitial and total aerosol size distributions, particle chemical composition and hygroscopicity and cloud droplet size distribution were measured, with a focus on comparing clean air masses with those affected by local sources. On average, the polluted air contained more particles than the clean air masses, and generally the concentrations decreased during cloud events. Cloud processing was found to take place, especially in the clean air masses, and to a lesser extent in the polluted air. Some, mostly minor, differences in the average particle chemical composition between the air masses were observed. The average size and number concentration of activating particles were quite similar for both air masses, producing average droplet populations with only minor distinctions. As a case study, a long cloud event was analyzed in detail, with a special focus on the emissions from local sources, including a paper mill and a heating plant. This revealed larger variations in particle and cloud properties than the analysis of the whole data set. Clear differences in the total (between 214 and 2200 cm-3) and accumulation mode particle concentrations (between 62 and 169 cm-3) were observed. Particle chemical composition, especially the concentrations of organics (between 0.42 and 1.28 μg m-3) and sulfate (between 0.16 and 4.43 μg m-3), varied considerably. This affected the hygroscopic growth factor: for example, for 100 nm particles the range was from 1.21 to 1.45 at 90% relative humidity. Particularly, large particles, high hygroscopicities and elevated amounts of inorganics were linked with the pollutant plumes. Moreover, the particle hygroscopicity distributions in the polluted air were clearly bimodal, indicating externally mixed aerosol. The variable conditions also had an impact on cloud droplet

  10. Size distributions of mineral aerosols and dust emission flux observed over Horqin Sandy Land area in northern China

    NASA Astrophysics Data System (ADS)

    Li, X.; Zhang, H. S.

    2013-01-01

    Size distribution of mineral aerosols is of primary importance in determining their residence time in atmosphere, transport patterns, removal mechanisms as well as their effects on climate and human health. This study aims to obtain dust particle size distribution and size-resolved dust emission flux under different weather conditions over a sandy land area in northern China (Horqin Sandy Land, Inner Mongolia), using the observational data from Horqin sandstorm monitoring station in the spring of 2010 and 2012. Dust (PM20) mass concentration was measured by a 10-stage quartz crystal microbalance (QCM) cascade impactor. The statistical results indicate that finer dust particles (r ≤ 1.0 μm) take a large proportion of all PM20 concentration under clear-day conditions, while coarser dust particles (r ≥ 2.5 μm) concentration increased under dust-day conditions, with the peak occurring between 4-7 μm. The dust particle size distributions during the pre-dust-emission and dust-emission periods of a dust event on 7 April 2012 have similar features to the statistical results. During the dust event, the magnitude of dust emission flux of all sizes increased about one or two orders (0.1-10 μg m-2 s-1) as u* increase from 0.54 to 1.29 m s-1. The maximum total F value was about 43.0 μg m-2 s-1 and the maximum size-resolved F(Ddi) is 12.3 μg m-2 s-1 in 0.3-0.45 μm size bin when u* is 1.29 m s-1. Dust advection has effects on airborne dust size distribution, making the proportion of dust particles of different sizes more uniform, as observed in a non-local dust event on 19 April 2012.

  11. Vertical structure and size distributions of Martian aerosols from solar occultation measurements

    NASA Technical Reports Server (NTRS)

    Chassefiere, E.; Blamont, J. E.; Krasnopol'skii, V. A.; Korablev, O. I.; Atreya, S. K.; West, R. A.

    1992-01-01

    Phobos 2 spectrometer measurements of solar occultations close to the evening terminator have furnished data on the vertical structure of the Martian aerosols near the northern spring equinox. Since the thermal structure derived from saturated IR profiles of water vapor does not allow the reaching of the CO2 frost point at cloud altitudes, said clouds' particles may be formed by H2O ice. Dust was also monitored at two wavelengths; it is assumed that the dust particles are levitated by eddy mixing. A parallel is drawn between these thin clouds and the polar mesospheric clouds observed on earth.

  12. Monitoring aerosol elemental composition in particle size fractions of long-range transport

    NASA Astrophysics Data System (ADS)

    Metternich, P.; Georgii, H.-W.; Groeneveld, K. O.

    1983-04-01

    Collection of atmospheric samples was performed at Malta, a semi-remote environment in the Mediterranean, in case of long-range transport studies of pollutants and natural substances. Using PIXE as a non-destructive trace-element analytical tool, the elemental composition of these samples was determined. Atmospheric concentrations obtained in this study were of one magnitude higher than those observed over the open North Alantic in purely marine air. For most of the anomalously enriched elements in the Mediterranean aerosol, the high concentrations can be explained by long-range transport.

  13. Graphical aerosol classification method using aerosol relative optical depth

    NASA Astrophysics Data System (ADS)

    Chen, Qi-Xiang; Yuan, Yuan; Shuai, Yong; Tan, He-Ping

    2016-06-01

    A simple graphical method is presented to classify aerosol types based on a combination of aerosol optical thickness (AOT) and aerosol relative optical thickness (AROT). Six aerosol types, including maritime (MA), desert dust (DD), continental (CO), sub-continental (SC), urban industry (UI) and biomass burning (BB), are discriminated in a two dimensional space of AOT440 and AROT1020/440. Numerical calculations are performed using MIE theory based on a multi log-normal particle size distribution, and the AROT ranges for each aerosol type are determined. More than 5 years of daily observations from 8 representative aerosol sites are applied to the method to confirm spatial applicability. Finally, 3 individual cases are analyzed according to their specific aerosol status. The outcomes indicate that the new graphical method coordinates well with regional characteristics and is also able to distinguish aerosol variations in individual situations. This technique demonstrates a novel way to estimate different aerosol types and provide information on radiative forcing calculations and satellite data corrections.

  14. Characterization of Florida red tide aerosol and the temporal profile of aerosol concentration

    PubMed Central

    Cheng, Yung Sung; Zhou, Yue; Pierce, Richard H.; Henry, Mike; Baden, Daniel G.

    2009-01-01

    Red tide aerosols containing aerosolized brevetoxins are produced during the red tide bloom and transported by wind to coastal areas of Florida. This study reports the characterization of Florida red tide aerosols in human volunteer studies, in which an asthma cohort spent 1 h on Siesta Beach (Sarasota, Florida) during aerosolized red tide events and non-exposure periods. Aerosol concentrations, brevetoxin levels, and particle size distribution were measured. Hourly filter samples were taken and analyzed for brevetoxin and NaCl concentrations. In addition, the aerosol mass concentration was monitored in real time. The results indicated that during a non-exposure period in October 2004, no brevetoxin was detected in the water, resulting in non-detectable levels of brevetoxin in the aerosol. In March 2005, the time-averaged concentrations of brevetoxins in water samples were moderate, in the range of 5–10 μg/L, and the corresponding brevetoxin level of Florida red tide aerosol ranged between 21 and 39 ng/m3. The temporal profiles of red tide aerosol concentration in terms of mass, NaCl, and brevetoxin were in good agreement, indicating that NaCl and brevetoxins are components of the red tide aerosol. By continuously monitoring the marine aerosol and wind direction at Siesta Beach, we observed that the marine aerosol concentration varied as the wind direction changed. The temporal profile of the Florida red tide aerosol during a sampling period could be explained generally with the variation of wind direction. PMID:19879288

  15. Performance of High Flow Rate Personal Respirable Samplers When Challenged with Mineral Aerosols of Different Particle Size Distributions.

    PubMed

    Stacey, Peter; Thorpe, Andrew; Echt, Alan

    2016-05-01

    It is thought that the performance of respirable samplers may vary when exposed to dust aerosols with different particle sizes and wind speeds. This study investigated the performance of the GK 4.16 (RASCAL), GK 2.69, PPI 8, and FSP 10, high flow rate personal samplers when exposed to aerosols of mineral dust in a wind tunnel at two different wind speeds (1 and 2 m s(-1)) and orientations (towards and side-on to the source of emission). The mass median aerodynamic diameter of four aerosolized test dusts ranged from 8 to 25 µm with geometric standard deviations from 1.6 to 2 µm. The performance of each sampler type was compared with that of the SIMPEDS (Higgins-Dewell design) sampler. There was slight evidence to suggest that the performance of the FSP 10 is affected by the direction of the inlet relative to the air flow, although this was not significant when most respirable dust concentrations were compared, possibly due to the variability of paired dust concentration results. The GK 2.69, RASCAL, and PPI 8 samplers had similar performances, although the results when side-on to the emission source were generally slightly lower than the SIMPEDS. Despite slight differences between respirable dust concentrations the respirable crystalline silica values were not significantly different from the SIMPEDS. The GK family of cyclones obtained most precise results and more closely matched the SIMPEDS. A comparison with dust concentration results from previous calm air chamber studies (where wind speeds were < 0.4 m s(-1)) found that the relative performance between samplers was similar to those observed in this work indicating consistent performance relative to the SIMPEDS in both calm and moving air. PMID:26865560

  16. Performance of High Flow Rate Personal Respirable Samplers When Challenged with Mineral Aerosols of Different Particle Size Distributions

    PubMed Central

    Stacey, Peter; Thorpe, Andrew; Echt, Alan

    2016-01-01

    It is thought that the performance of respirable samplers may vary when exposed to dust aerosols with different particle sizes and wind speeds. This study investigated the performance of the GK 4.16 (RASCAL), GK 2.69, PPI 8, and FSP 10, high flow rate personal samplers when exposed to aerosols of mineral dust in a wind tunnel at two different wind speeds (1 and 2 m s−1) and orientations (towards and side-on to the source of emission). The mass median aerodynamic diameter of four aerosolized test dusts ranged from 8 to 25 µm with geometric standard deviations from 1.6 to 2 µm. The performance of each sampler type was compared with that of the SIMPEDS (Higgins–Dewell design) sampler. There was slight evidence to suggest that the performance of the FSP 10 is affected by the direction of the inlet relative to the air flow, although this was not significant when most respirable dust concentrations were compared, possibly due to the variability of paired dust concentration results. The GK 2.69, RASCAL, and PPI 8 samplers had similar performances, although the results when side-on to the emission source were generally slightly lower than the SIMPEDS. Despite slight differences between respirable dust concentrations the respirable crystalline silica values were not significantly different from the SIMPEDS. The GK family of cyclones obtained most precise results and more closely matched the SIMPEDS. A comparison with dust concentration results from previous calm air chamber studies (where wind speeds were < 0.4 m s−1) found that the relative performance between samplers was similar to those observed in this work indicating consistent performance relative to the SIMPEDS in both calm and moving air. PMID:26865560

  17. Continuous scanning of the mobility and size distribution of charged clusters and nanometer particles in atmospheric air and the Balanced Scanning Mobility Analyzer BSMA

    NASA Astrophysics Data System (ADS)

    Tammet, H.

    2006-12-01

    Measuring of charged nanometer particles in atmospheric air is a routine task in research on atmospheric electricity, where these particles are called the atmospheric ions. An aspiration condenser is the most popular instrument for measuring atmospheric ions. Continuous scanning of a mobility distribution is possible when the aspiration condenser is connected as an arm of a balanced bridge. Transfer function of an aspiration condenser is calculated according to the measurements of geometric dimensions, air flow rate, driving voltage, and electric current. The most complicated phase of the calibration is the estimation of the inlet loss of ions due to the Brownian deposition. The available models of ion deposition on the protective inlet screen and the inlet control electrofilter have the uncertainty of about 20%. To keep the uncertainty of measurements low the adsorption should not exceed a few tens of percent. The online conversion of the mobility distribution to the size distribution and a correct reduction of inlet losses are possible when air temperature and pressure are measured simultaneously with the mobility distribution. Two instruments called the Balanced Scanning Mobility Analyzers (BSMA) were manufactured and tested in routine atmospheric measurements. The concentration of atmospheric ions of the size of about a few nanometers is very low and a high air flow rate is required to collect enough of ion current. The air flow of 52 l/s exceeds the air flow in usual aerosol instruments by 2-3 orders of magnitude. The high flow rate reduces the time of ion passage to 60 ms and the heating of air in an analyzer to 0.2 K, which suppresses a possible transformation of ions inside the instrument. The mobility range of the BSMA of 0.032-3.2 cm 2 V - 1 s - 1 is logarithmically uniformly divided into 16 fractions. The size distribution is presented by 12 fractions in the diameter range of 0.4-7.5 nm. The measurement noise of a fraction concentration is typically

  18. On the competition among aerosol number, size and composition in predicting CCN variability: a multi-annual field study in an urbanized desert

    NASA Astrophysics Data System (ADS)

    Crosbie, E.; Youn, J.-S.; Balch, B.; Wonaschütz, A.; Shingler, T.; Wang, Z.; Conant, W. C.; Betterton, E. A.; Sorooshian, A.

    2015-02-01

    A two-year dataset of measured CCN concentrations at 0.2% supersaturation is combined with aerosol size distribution and aerosol chemistry data to probe the effects of aerosol number concentrations, size distribution and composition on CCN patterns. Data have been collected over a period of two years (2012-2014) in central Tucson, Arizona: a significant urban area surrounded by a sparsely populated desert. Average CCN concentrations are typically lowest in spring (233 cm-3), highest in winter (430 cm-3) and have a secondary peak during the North American Monsoon season (July to September; 372 cm-3). There is significant variability outside of seasonal patterns with extreme concentrations (1 and 99% levels) ranging from 56 to 1945 cm-3 as measured during the winter, the season with highest variability. Modeled CCN concentrations based on fixed chemical composition achieve better closure in winter, with size and number alone able to predict 82% of the variance in CCN concentration. Changes in aerosol chemistry are typically aligned with changes in size and aerosol number, such that composition can be parameterized even though it is still variable. In summer, models based on fixed chemical composition explain at best only 41% (pre-monsoon) and 36% (monsoon) of the variance. This is attributed to the effects of secondary organic aerosol (SOA) production, the competition between new particle formation and condensational growth, and the complex interaction of meteorology, regional and local emissions, and multi-phase chemistry during the North American Monsoon. Chemical composition is found to be an important factor for improving predictability in spring and on longer timescales in winter. Regimes where parameterized models exhibit improved predictive skill are typically explained by strong relationships between CCN concentrations and the prevailing meteorology and dominant aerosol chemistry mechanisms suggesting that similar findings could be possible in other locations

  19. On the competition among aerosol number, size and composition in predicting CCN variability: a multi-annual field study in an urbanized desert

    NASA Astrophysics Data System (ADS)

    Crosbie, E.; Youn, J.-S.; Balch, B.; Wonaschütz, A.; Shingler, T.; Wang, Z.; Conant, W. C.; Betterton, E. A.; Sorooshian, A.

    2015-06-01

    A 2-year data set of measured CCN (cloud condensation nuclei) concentrations at 0.2 % supersaturation is combined with aerosol size distribution and aerosol composition data to probe the effects of aerosol number concentrations, size distribution and composition on CCN patterns. Data were collected over a period of 2 years (2012-2014) in central Tucson, Arizona: a significant urban area surrounded by a sparsely populated desert. Average CCN concentrations are typically lowest in spring (233 cm-3), highest in winter (430 cm-3) and have a secondary peak during the North American monsoon season (July to September; 372 cm-3). There is significant variability outside of seasonal patterns, with extreme concentrations (1 and 99 % levels) ranging from 56 to 1945 cm-3 as measured during the winter, the season with highest variability. Modeled CCN concentrations based on fixed chemical composition achieve better closure in winter, with size and number alone able to predict 82 % of the variance in CCN concentration. Changes in aerosol chemical composition are typically aligned with changes in size and aerosol number, such that hygroscopicity can be parameterized even though it is still variable. In summer, models based on fixed chemical composition explain at best only 41 % (pre-monsoon) and 36 % (monsoon) of the variance. This is attributed to the effects of secondary organic aerosol (SOA) production, the competition between new particle formation and condensational growth, the complex interaction of meteorology, regional and local emissions and multi-phase chemistry during the North American monsoon. Chemical composition is found to be an important factor for improving predictability in spring and on longer timescales in winter. Parameterized models typically exhibit improved predictive skill when there are strong relationships between CCN concentrations and the prevailing meteorology and dominant aerosol physicochemical processes, suggesting that similar findings could be

  20. On the competition among aerosol number, size and composition in predicting CCN variability: a multi-annual field study in an urbanized desert

    NASA Astrophysics Data System (ADS)

    Crosbie, Ewan; Youn, Jong-Sang; Balch, Brian; Wonaschuetz, Anna; Shingler, Taylor; Wang, Zhen; Conant, William; Betterton, Eric; Sorooshian, Armin

    2015-04-01

    A two-year dataset of measured CCN concentrations at 0.2% supersaturation is combined with aerosol size distribution and aerosol chemistry data to probe the effects of aerosol number concentrations, size distribution and composition on CCN patterns. Data have been collected over a period of two years (2012-2014) in central Tucson, Arizona: a significant urban area surrounded by a sparsely populated desert. Average CCN concentrations are typically lowest in spring (233 cm-3), highest in winter (430 cm-3) and have a secondary peak during the North American Monsoon season (July to September; 372 cm-3). There is significant variability outside of seasonal patterns with extreme concentrations (1% and 99% levels) ranging from 56 cm-3 to 1945 cm-3 as measured during the winter, the season with highest variability. Modeled CCN concentrations based on fixed chemical composition achieve better closure in winter, with size and number alone able to predict 82% of the variance in CCN concentration. Changes in aerosol chemistry are typically aligned with changes in size and aerosol number, such that composition can be parameterized even though it is still variable. In summer, models based on fixed chemical composition explain at best only 41% (pre-monsoon) and 36% (monsoon) of the variance. This is attributed to the effects of secondary organic aerosol (SOA) production, the competition between new particle formation and condensational growth, and the complex interaction of meteorology, regional and local emissions, and multi-phase chemistry during the North American Monsoon. Chemical composition is found to be an important factor for improving predictability in spring and on longer timescales in winter. Regimes where parameterized models exhibit improved predictive skill are typically explained by strong relationships between CCN concentrations and the prevailing meteorology and dominant aerosol chemistry mechanisms suggesting that similar findings could be possible in other

  1. On the competition among aerosol number, size and composition in predicting CCN variability: a multi-annual field study in an urbanized desert

    PubMed Central

    Crosbie, E.; Youn, J.-S.; Balch, B.; Wonaschütz, A.; Shingler, T.; Wang, Z.; Conant, W. C.; Betterton, E. A.; Sorooshian, A.

    2015-01-01

    A 2-year data set of measured CCN (cloud condensation nuclei) concentrations at 0.2 % supersaturation is combined with aerosol size distribution and aerosol composition data to probe the effects of aerosol number concentrations, size distribution and composition on CCN patterns. Data were collected over a period of 2 years (2012–2014) in central Tucson, Arizona: a significant urban area surrounded by a sparsely populated desert. Average CCN concentrations are typically lowest in spring (233 cm−3), highest in winter (430 cm−3) and have a secondary peak during the North American monsoon season (July to September; 372 cm−3). There is significant variability outside of seasonal patterns, with extreme concentrations (1 and 99 % levels) ranging from 56 to 1945 cm−3 as measured during the winter, the season with highest variability. Modeled CCN concentrations based on fixed chemical composition achieve better closure in winter, with size and number alone able to predict 82% of the variance in CCN concentration. Changes in aerosol chemical composition are typically aligned with changes in size and aerosol number, such that hygroscopicity can be parameterized even though it is still variable. In summer, models based on fixed chemical composition explain at best only 41% (pre-monsoon) and 36% (monsoon) of the variance. This is attributed to the effects of secondary organic aerosol (SOA) production, the competition between new particle formation and condensational growth, the complex interaction of meteorology, regional and local emissions and multi-phase chemistry during the North American monsoon. Chemical composition is found to be an important factor for improving predictability in spring and on longer timescales in winter. Parameterized models typically exhibit improved predictive skill when there are strong relationships between CCN concentrations and the prevailing meteorology and dominant aerosol physicochemical processes, suggesting that similar findings

  2. Coagulation effect on the activity size distributions of long lived radon progeny aerosols and its application to atmospheric residence time estimation techniques.

    PubMed

    Anand, S; Mayya, Y S

    2015-03-01

    The long lived naturally occurring radon progeny species in the atmosphere, namely (210)Pb, (210)Bi and (210)Po, have been used as important tracers for understanding the atmospheric mixing processes and estimating aerosol residence times. Several observations in the past have shown that the activity size distribution of these species peaks at larger particle sizes as compared to the short lived radon progeny species - an effect that has been attributed to the process of coagulation of the background aerosols to which they are attached. To address this issue, a mathematical equation is derived for the activity-size distribution of tracer species by formulating a generalized distribution function for the number of tracer atoms present in coagulating background particles in the presence of radioactive decay and removal. A set of these equations is numerically solved for the progeny chain using Fuchs coagulation kernel combined with a realistic steady-state aerosol size spectrum that includes nucleation, accumulation and coarse mode components. The important findings are: (i) larger shifts in the modal sizes of (210)Pb and (210)Po at higher aerosol concentrations such as that found in certain Asian urban regions (ii) enrichment of tracer specific activity on particles as compared to that predicted by pure attachment laws (iii) sharp decline of daughter-to-parent activity ratios for decreasing particle sizes. The implication of the results to size-fractionated residence time estimation techniques is highlighted. A coagulation corrected graphical approach is presented for estimating the residence times from the size-segregated activity ratios of (210)Bi and (210)Po with respect to (210)Pb. The discrepancy between the residence times predicted by conventional formula and the coagulation corrected approach for specified activity ratios increases at higher atmospheric aerosol number concentrations (>10(10) #/m(3)) for smaller sizes (<1 μm). The results are further

  3. Size distributions of organic nitrogen and carbon in remote marine aerosols: Evidence of marine biological origin based on their isotopic ratios

    NASA Astrophysics Data System (ADS)

    Miyazaki, Yuzo; Kawamura, Kimitaka; Sawano, Maki

    2010-03-01

    Size-segregated aerosol samples were collected over the western North Pacific in summer 2008 for the measurements of organic nitrogen (ON) and organic carbon (OC). ON and OC showed bimodal size distributions. Their concentrations showed positive correlation with those of biogenic tracers, methanesulfonic acid (MSA) and azelaic acid (C9). We found that average ON and OC concentrations were twice greater in aerosols collected in the oceanic region with higher biological productivity than in the regions with lower productivity. The average ON/OC ratios are higher (0.49 ± 0.11) in more biologically influenced aerosols than those (0.35 ± 0.10) in less influenced aerosols. Stable carbon isotopic analysis indicates that marine-derived carbon accounted for ˜46-72% of total carbon in more biologically influenced aerosols. These results provide evidence that organic aerosols in this region are enriched in ON that is linked to oceanic biological activity and the subsequent emissions to the atmosphere.

  4. Non-sea-salt sulfate, methanesulfonate, and nitrate aerosol concentrations and size distributions at Cape Grim, Tasmania

    NASA Astrophysics Data System (ADS)

    Andreae, Meinrat O.; Elbert, Wolfgang; Cai, Yong; Andreae, Tracey W.; Gras, John

    1999-09-01

    We collected weekly aerosol samples using high-volume impactors over a period of 20 months (1988-1990) at the Cape Grim baseline station on the northwestern coast of Tasmania, Australia. The samples were analyzed for soluble ionic constituents, including sulfate, methanesulfonate (MS-), ammonium, nitrate, and the major sea-salt ions. The sea-salt component showed only a slight seasonal variation, whereas the non-sea-salt (nss) ions all had pronounced summer maxima. Significant interannual variability was seen between the nss ion concentrations measured during the two summers investigated. Nss sulfate and MS- were present both in the fine and coarse aerosol fractions, in the latter presumably associated with sea-salt particles. During the winter period, there was more nss sulfate in the coarse fraction than in the fine fraction. These observations are consistent with an important role of liquid-phase oxidation in haze and cloud droplets for the production of nss sulfate aerosol. The seasonal behavior of the sulfur and nitrogen species at Cape Grim and their mutual correlations suggest that DMS oxidation is the dominant sulfur source during summer, while nonbiogenic sulfur sources make significant contributions to nss sulfate outside of this season. Correlations of CN and CCN concentrations with nss sulfate, MS-, and wind speed suggest that DMS oxidation and, to a lesser extent, seaspray formation contributes to CN and CCN populations. The contrast between the weak seasonality of the sea-salt component and the pronounced seasonal behavior in both sulfur species and CCN supports the central role of biogenic DMS emissions as precursors of CCN in this region, at least in the biologically productive season.

  5. Evolution of size-segregated aerosol mass concentration during the Antarctic summer at Northern Foothills, Victoria Land

    NASA Astrophysics Data System (ADS)

    Illuminati, Silvia; Bau, Sébastien; Annibaldi, Anna; Mantini, Caterina; Libani, Giulia; Truzzi, Cristina; Scarponi, Giuseppe

    2016-01-01

    Within the framework of the Italian National Programm for Antarctic Research (PNRA), the first direct gravimetric measurements of size-segregated aerosol fractions were carried out at Faraglione Camp, ˜3-km far from the Italian station "M. Zucchelli" (Terra Nova Bay, Ross Sea), during the 2014-2015 austral summer. A six-stage high-volume cascade impactor with size classes between 10 μm and 0.49 μm, and, in parallel, for comparison purposes, a PM10 high-volume sampler (50% cut-off aerodynamic diameter of 10 μm) were used. A 10-day sampling strategy was adopted. Aerosol mass measurements were carried out before and after exposure by using a microbalance specifically designed for the filter weight and placed inside a glove bag in order to maintain stable temperature and humidity conditions during weighing sessions. Measured atmospheric concentrations (referred to the "actual air conditions" of mean temperature of 268 K and mean pressure of 975 hPa) of size-segregated aerosol fractions showed the following values, given as size range, means (interquartile range): Dp < 0.49 μm, 0.33 (0.26-0.34) μg m-3; 0.49-0.95 μm, 0.20 (0.19-0.24) μg m-3; 0.95-1.5 μm, 0.16 (0.13-0.21) μg m-3; 1.5-3.0 μm 0.075 (0.05-0.11) μg m-3; 3.0-7.2 μm 0.12 (0.02-0.19) μg m-3; 7.2-10 μm 0.06 (0.01-0.03) μg m-3. The average mass concentration of the total PM10 at Faraglione Camp for the entire sampling period was 0.92 (0.67-1.1) μg m-3. Although a great variability, the aerosol mass concentration showed a tri-modal distribution, with an accumulation mode (in the range 0.1-1.0 μm) and two coarse modes (CM1 in the range 1.0-3.0 μm, and CM2 in the range 3.0-10 μm). From 50% to 90% of the PM10 mass comes from particles of a size smaller than 1.0 μm. The two coarse modes represented from ˜5% to ˜35% of the PM10, showing opposite seasonal trends (CM1 decreased while CM2 increased). During summer, PM10 mass concentration increased to a maximum of ˜1.6 μg m-3 at mid-December, while

  6. Raman Lidar Measurements of Aerosol Extinction and Backscattering. Report 2; Derivation of Aerosol Real Refractive Index, Single-Scattering Albedo, and Humidification Factor using Raman Lidar and Aircraft Size Distribution

    NASA Technical Reports Server (NTRS)

    Ferrare, R. A.; Melfi, S. H.; Whiteman, D. N.; Evans, K. D.; Poellot, M.; Kaufman, Y. J.

    1998-01-01

    Aerosol backscattering and extinction profiles measured by the NASA Goddard Space Flight Center Scanning Raman Lidar (SRL) during the remote cloud sensing (RCS) intensive operations period (IOP) at the Department of Energy Atmospheric Radiation Measurement (ARM) southern Great Plains (SGP) site during two nights in April 1994 are discussed. These profiles are shown to be consistent with the simultaneous aerosol size distribution measurements made by a PCASP (Passive Cavity Aerosol Spectrometer Probe) optical particle counter flown on the University of North Dakota Citation aircraft. We describe a technique which uses both lidar and PCASP measurements to derive the dependence of particle size on relative humidity, the aerosol real refractive index n, and estimate the effective single-scattering albedo Omega(sub 0). Values of n ranged between 1.4-1.5 (dry) and 1.37-1.47 (wet); Omega(sub 0) varied between 0.7 and 1.0. The single-scattering albedo derived from this technique is sensitive to the manner in which absorbing particles are represented in the aerosol mixture; representing the absorbing particles as an internal mixture rather than the external mixture assumed here results in generally higher values of Omega(sub 0). The lidar measurements indicate that the change in particle size with relative humidity as measured by the PCASP can be represented in the form discussed by Hattel with the exponent gamma = 0.3 + or - 0.05. The variations in aerosol optical and physical characteristics captured in the lidar and aircraft size distribution measurements are discussed in the context of the meteorological conditions observed during the experiment.

  7. AMS Measurements in National Parks of Aerosol Mass, Size and Composition, Comparison with Filter Samples and Correlation with Particle Hygroscopicity and Optical Extinction Properties

    NASA Astrophysics Data System (ADS)

    Alexander, M.; Taylor, N. F.; Collins, D. R.; Kumar, N.; Allen, J.; Newburn, M.; Lowenthal, D. H.; Zielinska, B.

    2011-12-01

    We report a comparison of results from aerosol studies at Great Smoky Mountain National Park (2006), Mt. Rainier National Park (2009) and Acadia National Park (2011), all class I visibility areas associated with IMPROVE (Interagency Monitoring of Protected Visual Environments) sites. This collaborative study was sponsored by the Electric Power Research Institute (EPRI) and was done with the cooperation of the National Park Service and the EPA. The atmospheric aerosol composition in these sites is influenced by a number of anthropogenic as well as biogenic sources, providing a rich environment for fundamental aerosol studies. The primary purpose of these studies was to add state-of-the-art aerosol instrumentation to the standard light extinction and aerosol measurements at the site, used to determine parameters for the IMPROVE light extinction reconstruction equation, adopted by the EPA to estimate light extinction from atmospheric aerosol concentrations and Rayleigh scattering. The combination of these diverse measurements also provides significant insight into fundamental aerosol properties such as aging and radiative forcing. New instrumentation included a quadrupole aerosol mass spectrometer (Aerodyne Q-AMS-Smoky Mountain Study), a high resolution aerosol time-of-flight mass spectrometer (Aerodyne HR-ToF-AMS - Mt. Rainier and Acadia studies) for real time measurements that directly address the relationship between sulfate, nitrate, and OC size and concentration, which is related to cloud and dry gas-to-particle conversion as air masses age during transport, the relationship between WSOC hygroscopic growth and oxygenated organic (OOA) composition, the OCM/OC ratio, and the chemical composition that determines the ambient hygroscopic state. The OCM/OC ratio and organic water uptake was addressed with high-volume and medium volume PM2.5 aerosol samples. Aerosols were collected daily on Teflon coated glass fiber filters (TGFF) in four high-volume PM2.5 samplers

  8. Particle size-dependent leakage and losses of aerosols in respirators.

    PubMed

    Holton, P M; Tackett, D L; Willeke, K

    1987-10-01

    Measuring particle size-dependent leakage into and losses inside a respirator reveals the deposition mechanisms occurring at the leak site and the flow dynamics inside the respirator. This study investigated particle size-dependent leakage and deposition within the mask by examining the leakage into the mask for different hole locations, probe locations, hole shapes, hole lengths and hole sizes. The shape of the leak has an effect on particle size-dependent leakage. Probe and leak location tests indicated that not only does the total measured leakage change but also the size-dependence of the leakage changes depending on the leak and probe locations. When the leak site is in the chin area, the clean air entering through the filters at the chin helps to carry the inward leakage into the breathing zone. Particle size-dependent leakage does occur and is due to both inertial entry losses at the leak site and within the mask, and diffusional losses within the mask and leak site. Particle size-dependent curves change shape as the hole size changes with relatively more larger particles entering through the small hole size. PMID:3687729

  9. Size distributions of nano/micron dicarboxylic acids and inorganic ions in suburban PM episode and non-episodic aerosol

    NASA Astrophysics Data System (ADS)

    Hsieh, Li-Ying; Kuo, Su-Ching; Chen, Chien-Lung; Tsai, Ying I.

    The distribution of nano/micron dicarboxylic acids and inorganic ions in size-segregated suburban aerosol of southern Taiwan was studied for a PM episode and a non-episodic pollution period, revealing for the first time the distribution of these nanoscale particles in suburban aerosols. Inorganic species, especially nitrate, were present in higher concentrations during the PM episode. A combination of gas-to-nuclei conversion of nitrate particles and accumulation of secondary photochemical products originating from traffic-related emissions was likely a crucial cause of the PM episode. Sulfate, ammonium, and oxalic acid were the dominant anion, cation, and dicarboxylic acid, respectively, accounting for a minimum of 49% of the total anion, cation or dicarboxylic acid mass. Peak concentrations of these species occurred at 0.54 μm in the droplet mode during both non-episodic and PM episode periods, indicating an association with cloud-processed particles. On average, sulfate concentration was 16-17 times that of oxalic acid. Oxalic acid was nevertheless the most abundant dicarboxylic acid during both periods, followed by succinic, malonic, maleic, malic and tartaric acid. The mass median aerodynamic diameter (MMAD) of oxalic acid was 0.77 μm with a bi-modal presence at 0.54 μm and 18 nm during non-episodic pollution and an MMAD of 0.67 μm with mono-modal presence at 0.54 μm in PM episode aerosol. The concomitant formation of malonic acid and oxalic acid was attributed to in-cloud processes. During the PM episode in the 5-100 nm nanoscale range, an oxalic acid/sulfate mass ratio of 40.2-82.3% suggested a stronger formation potential for oxalic acid than for sulfate in the nuclei mode. For total cations (TC), total inorganic anions (TIA) and total dicarboxylic acids (TDA), major contributing particles were in the droplet mode, with least in the nuclei mode. The ratio of TDA to TIA in the nuclei mode increased greatly from 8.40% during the non-episodic pollution

  10. Development of a method for fast and automatic radiocarbon measurement of aerosol samples by online coupling of an elemental analyzer with a MICADAS AMS

    NASA Astrophysics Data System (ADS)

    Salazar, G.; Zhang, Y. L.; Agrios, K.; Szidat, S.

    2015-10-01

    A fast and automatic method for radiocarbon analysis of aerosol samples is presented. This type of analysis requires high number of sample measurements of low carbon masses, but accepts precisions lower than for carbon dating analysis. The method is based on online Trapping CO2 and coupling an elemental analyzer with a MICADAS AMS by means of a gas interface. It gives similar results to a previously validated reference method for the same set of samples. This method is fast and automatic and typically provides uncertainties of 1.5-5% for representative aerosol samples. It proves to be robust and reliable and allows for overnight and unattended measurements. A constant and cross contamination correction is included, which indicates a constant contamination of 1.4 ± 0.2 μg C with 70 ± 7 pMC and a cross contamination of (0.2 ± 0.1)% from the previous sample. A Real-time online coupling version of the method was also investigated. It shows promising results for standard materials with slightly higher uncertainties than the Trapping online approach.

  11. The effect of grid transparency and finite collector size on determining ion temperature and density by the retarding potential analyzer

    NASA Technical Reports Server (NTRS)

    Troy, B. E., Jr.; Maier, E. J.

    1973-01-01

    The analysis of ion data from retarding potential analyzers (RPA's) is generally done under the planar approximation, which assumes that the grid transparency is constant with angle of incidence and that all ions reaching the plane of the collectors are collected. These approximations are not valid for situations in which the ion thermal velocity is comparable to the vehicle velocity, causing ions to enter the RPA with high average transverse velocity. To investigate these effects, the current-voltage curves for H+ at 4000 K were calculated, taking into account the finite collector size and the variation of grid transparency with angle. These curves are then analyzed under the planar approximation. The results show that only small errors in temperature and density are introduced for an RPA with typical dimensions; and that even when the density error is substantial for non-typical dimensions, the temperature error remains minimal.

  12. COMPARISON OF TWO PARTICLE-SIZE SPECTROMETERS FOR AMBIENT AEROSOL MEASUREMENTS. (R827354C002)

    EPA Science Inventory

    There is an ongoing debate on the question which size fraction of particles in ambient air may be responsible for human health effects observed in epidemiological studies. Since there is no single instrument available for the measurement of the particle-size distribution over ...

  13. Size-resolved airborne particulate oxalic and related secondary organic aerosol species in the urban atmosphere of Chengdu, China

    NASA Astrophysics Data System (ADS)

    Cheng, Chunlei; Wang, Gehui; Meng, Jingjing; Wang, Qiyuan; Cao, Junji; Li, Jianjun; Wang, Jiayuan

    2015-07-01

    Size-segregated (9-stages) airborne particles during winter in Chengdu city of China were collected on a day/night basis and determined for dicarboxylic acids (diacids), ketocarboxylic acids (ketoacids), α-dicarbonyls, inorganic ions, and water-soluble organic carbon and nitrogen (WSOC and WSON). Diacid concentration was higher in nighttime (1831 ± 607 ng m- 3) than in daytime (1532 ± 196 ng m- 3), whereas ketoacids and dicarbonyls showed little diurnal difference. Most of the organic compounds were enriched in the fine mode (< 2.1 μm) with a peak at the size range of 0.7-2.1 μm. In contrast, phthalic acid (Ph) and glyoxal (Gly) presented two equivalent peaks in the fine and coarse modes, which is at least in part due to the gas-phase oxidation of precursors and a subsequent partitioning into pre-existing particles. Liquid water content (LWC) of the fine mode particles was three times higher in nighttime than in daytime. The calculated in-situ pH (pHis) indicated that all the fine mode aerosols were acidic during the sampling period and more acidic in daytime than in nighttime. Robust correlations of the ratios of glyoxal/oxalic acid (Gly/C2) and glyoxylic acid/oxalic acid (ωC2/C2) with LWC in the samples suggest that the enhancement of LWC is favorable for oxidation of Gly and ωC2 to produce C2. Abundant K+ and Cl- in the fine mode particles and the strong correlations of K+ with WSOC, WSON and C2 indicate that secondary organic aerosols in the city are significantly affected by biomass burning emission.

  14. Chemical composition and size distribution of summertime PM2.5 at a high altitude remote location in the northeast of the Qinghai-Xizang (Tibet) Plateau: insights into aerosol sources and processing in free troposphere

    NASA Astrophysics Data System (ADS)

    Xu, J. Z.; Zhang, Q.; Wang, Z. B.; Yu, G. M.; Ge, X. L.; Qin, X.

    2015-05-01

    Aerosol filter samples were collected at a high-elevation mountain observatory (4180 m a.s.l.) in the northeastern part of the Qinghai-Xizang (Tibet) Plateau (QXP) during summer 2012 using a low-volume sampler and a micro-orifice uniform deposit impactor (MOUDI). These samples were analyzed for water-soluble inorganic ions (WSIs), organic carbon (OC), elemental carbon (EC), water-soluble organic carbon (WSOC), and total organic nitrogen (TON) to elucidate the size-resolved chemical composition of free tropospheric aerosols in the QXP region. The average mass concentration of the sum of the analyzed species in PM2.5 (particle matter) (WSIs + OC + EC + TON) was 3.74 μg sm-3, 36% of which was sulfate, 18% OC, 17 % nitrate, 10% ammonium, 6.6% calcium, 6.4% TON, 2.6% EC, 1.5 % sodium, 0.9% chloride, 0.5% magnesium, and 0.3% potassium. The size distributions of sulfate and ammonium peaked in the accumulation mode (0.32-0.56 μm), whereas the size distributions of both nitrate and calcium peaked in the range of 1.8-3.2 μm, suggesting the formation of nitrate on mineral dust. OC, EC and TON were also predominantly found in the accumulation mode. The bulk chemical composition and the average oxidation degree of water-soluble organic matter (WSOM) were assessed using a high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS). WSOM was found to be highly oxidized in all PM2.5 samples with an average oxygen-to-carbon atomic ratio (O / C) of 1.16 and an organic mass-to-organic carbon ratio (OM / OC) of 2.75. The highly oxidized WSOM was likely related to active cloud processing during upslope air mass transport coupled with strongly oxidizing environments caused by snow/ice photochemistry. High average ratios of OC / EC (7.6) and WSOC / OC (0.79) suggested that organic aerosols were primarily made of secondary species. Secondary organic aerosol (SOA) was estimated on average accounting for 80% (62-96%) of the PM2.5, indicating that SOA is an important component

  15. Freezing Drizzle Formation in Stably Stratified Layer Clouds. Part II: The Role of Giant Nuclei and Aerosol Particle Size Distribution and Solubility.

    NASA Astrophysics Data System (ADS)

    Geresdi, István; Rasmussen, Roy

    2005-07-01

    This paper investigates how the characteristics of aerosol particles (size distribution and solubility) as well as the presence of giant nuclei affect drizzle formation in stably stratified layer clouds. A new technique was developed to simulate the evolution of water drops from wet aerosol particles and implemented into a detailed microphysical model. The detailed microphysical model was incorporated into a one-dimensional parcel model and a two-dimensional version of the fifth-generation Pennsylvania State University-National Center for Atmospheric Research (PSU-NCAR) Mesoscale Model (MM5). Sensitivity experiments were performed with the parcel model using a constant updraft speed and with the two-dimensional model by simulating flow over a bell-shaped mountain. The results showed that 1) stably stratified clouds with weak updrafts (<10 cms-1) can form drizzle relatively rapidly for maritime size distributions with any aerosol particle solubility, and for continental size distributions with highly insoluble particles due to the low number of activated cloud condensation nuclei (CCN) (<100 cm-3), 2) drizzle is suppressed in stably stratified clouds with weak updrafts (<10 cms-1) for highly soluble urban and extreme urban size distributions, and 3) the presence of giant nuclei only has an effect on drizzle formation for the highly soluble continental aerosol size distributions.

  16. Size-segregated compositional analysis of aerosol particles collected in the European Arctic during the ACCACIA campaign

    NASA Astrophysics Data System (ADS)

    Young, G.; Jones, H. M.; Darbyshire, E.; Baustian, K. J.; McQuaid, J. B.; Bower, K. N.; Connolly, P. J.; Gallagher, M. W.; Choularton, T. W.

    2016-03-01

    Single-particle compositional analysis of filter samples collected on board the Facility for Airborne Atmospheric Measurements (FAAM) BAe-146 aircraft is presented for six flights during the springtime Aerosol-Cloud Coupling and Climate Interactions in the Arctic (ACCACIA) campaign (March-April 2013). Scanning electron microscopy was utilised to derive size-segregated particle compositions and size distributions, and these were compared to corresponding data from wing-mounted optical particle counters. Reasonable agreement between the calculated number size distributions was found. Significant variability in composition was observed, with differing external and internal mixing identified, between air mass trajectory cases based on HYbrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) analyses. Dominant particle classes were silicate-based dusts and sea salts, with particles notably rich in K and Ca detected in one case. Source regions varied from the Arctic Ocean and Greenland through to northern Russia and the European continent. Good agreement between the back trajectories was mirrored by comparable compositional trends between samples. Silicate dusts were identified in all cases, and the elemental composition of the dust was consistent for all samples except one. It is hypothesised that long-range, high-altitude transport was primarily responsible for this dust, with likely sources including the Asian arid regions.

  17. Evaluation of aerosol sizing characteristic of an impactor using imaging plate technique.

    PubMed

    Rahman, Naureen Mahbub; Iida, Takao; Saito, Fumihiro; Koarashi, Jun; Yamasaki, Keizou; Yamazawa, Hiromi; Moriizumi, Jun

    2007-01-01

    The activity-size distribution of radon decay products are normally determined using two approaches: direct and indirect. The present study utilises the direct approach to evaluate sizing information of a low pressure cascade impactor using imaging plate (IP) technique for radon decay products. The experiment verified the use of the collection media as suggested by the manufacturer of impactor and proposed a few improvements toward sizing characteristics of impactor. The obtained relative activity-size distribution of radon decay products presents a sharp unimodal log-normal distribution of the particle characterised by activity median aerodynamic diameter (AMAD) of 268 nm and geometric standard deviation (sigma(g)) of 1.66. The obtained data with all the suggested improvements were evaluated by the data obtained from a scanning mobility particle sizer (SMPS, Model 3934, TSI Inc), as reference data. The verification lead to a derivative area ratio of 0.803 between the reference and experimental data. PMID:16936289

  18. Observations of a bimodal size distribution for the aerosol particles on Mars by SPICAM/MEX

    NASA Astrophysics Data System (ADS)

    Fedorova, A.; Montmessin, F.; Rodin, A.; Korablev, O.; Määttänen, A.; Bertaux, J. L.

    2013-09-01

    We present first results of simultaneous analysis of the ultraviolet (UV) and infrared (IR) atmospheric extinctions obtained by SPICAM on Mars Express by means of solar occultations in the Martian atmosphere in the beginning of the northern summer (Ls=56-97°) at the middle northern and southern latitudes. Based on Mie scattering theory with adequate refraction indices for dust and H2O ice, a bimodal distribution of aerosol has been inferred from the SPICAM measurements at the altitudes from 10 to 50 km. The coarser mode exists for both H2O and dust particles with average radius of 1.3 and 0.7 μm, respectively, with number density from 0.01 to 10 particles to cm3. In addition, a small mode has been detected in both hemispheres with a radius of 0.03-0.07 μm and a number density from 1 cm-3 at 60 km to 1,000 cm-3 at 10-20 km.

  19. Performance of a focused cavity aerosol spectrometer for measurements in the stratosphere of particle size in the 0.06-2.0-micrometer-diameter range

    NASA Technical Reports Server (NTRS)

    Jonsson, H. H.; Wilson, J. C.; Brock, C. A.; Knollenberg, R. G.; Newton, R.; Dye, J. E.; Baumgardner, D.; Borrmann, S.; Ferry, G. V.; Pueschel, R.

    1995-01-01

    A focused cavity aerosol spectrometer aboard a NASA ER-2 high-altitude aircraft provided high-resolution measurements of the size of the stratospheric particles in the 0.06-2.0-micrometer-diameter range in flights following the eruption of Mount Pinatubo in 1991. Effects of anisokinetic sampling and evaporation in the sampling system were accounted for by means adapted and specifically developed for this instrument. Calibrations with monodisperse aerosol particles provided the instrument's response matrix, which upon inversion during data reduction yielded the particle size distributions. The resultant dataset is internally consistent and generally shows agreement to within a factor of 2 with comparable measurements simultaneously obtained by a condensation nuclei counter, a forward-scattering spectrometer probe, and aerosol particle impactors, as well as with nearby extinction profiles obtained by satellite measurements and with lidar measurements of backscatter.

  20. Global Aerosols

    Atmospheric Science Data Center

    2013-04-19

    ... sizes and from multiple sources, including biomass burning, mineral dust, sea salt and regional industrial pollution. A color scale is ... desert source region. Deserts are the main sources of mineral dust, and MISR obtains aerosol optical depth at visible wavelengths ...

  1. Production Mechanism, Number Concentration, Size Distribution, Chemical Composition, and Optical Properties of Sea Spray Aerosols Workshop, Summer 2012

    SciTech Connect

    Meskhidze, Nicholas

    2013-10-21

    The objective of this workshop was to address the most urgent open science questions for improved quantification of sea spray aerosol-radiation-climate interactions. Sea spray emission and its influence on global climate remains one of the most uncertain components of the aerosol-radiation-climate problem, but has received less attention than other aerosol processes (e.g. production of terrestrial secondary organic aerosols). Thus, the special emphasis was placed on the production flux of sea spray aerosol particles, their number concentration and chemical composition and properties.

  2. Seasonal variation and secondary formation of size-segregated aerosol water-soluble inorganic ions during pollution episodes in Beijing

    NASA Astrophysics Data System (ADS)

    Huang, Xiaojuan; Liu, Zirui; Zhang, Junke; Wen, Tianxue; Ji, Dongsheng; Wang, Yuesi

    2016-02-01

    Particulate matter (PM) pollution is a serious issue that has aroused great public attention in Beijing. To examine the seasonal characteristics of aerosols in typical pollution episodes, water-soluble inorganic ions (SO42 -, NO3-, NH4+, Cl-, K+, Na+, Ca2 + and Mg2 +) in size-segregated PM collected by an Anderson sampler (equipped with 50% effective cut-off diameters of 9.0, 5.8, 4.7, 3.3, 2.1, 1.1, 0.65, 0.43 μm and an after filter) were investigated in four intensive campaigns from June 2013 to May 2014 in the Beijing urban area. Pronounced seasonal variation of TWSIs in fine particles (aerodynamic diameter less than 2.1 μm) was observed, with the highest concentration in summer (71.5 ± 36.3 μg/m3) and the lowest in spring (28.1 ± 15.2 μg/m3). Different ion species presented different seasonal characteristics of mass concentration and size distribution, reflecting their different dominant sources. As the dominant component, SO42 -, NO3- and NH4+ (SNA) in fine particles appeared to play an important role in the formation of high PM pollution since its contribution to the TWSIs and PM2.1 mass increased significantly during pollution episodes. Due to the hygroscopic growth and enhanced secondary formation in the droplet mode (0.65-2.1 μm) from clean days to polluted days, the size distribution peak of SNA in the fine mode tended to shift from 0.43-0.65 μm to 0.65-2.1 μm. Relative humidity (RH) and temperature contributed to influence the secondary formation and regulate the size distributions of sulfates and nitrates. Partial correlation analysis found that high RH would promote the sulfur and nitrogen oxidation rates in the fine mode, while high temperature favored the sulfur oxidation rate in the condensation mode (0.43-0.65 μm) and reduced the nitrogen oxidation rate in the droplet mode (0.65-2.1 μm). The NO3-/SO42 - mass ratio in PM2.1 (73% of the samples) exceeded 1.0, suggesting that vehicle exhaust currently makes a greater contribution to aerosol

  3. Research on bio-aerosol monitoring based on normalized fluorescence voltage

    NASA Astrophysics Data System (ADS)

    Zhang, Pei; Zhao, Yongkai; Xiao, Yanfen; Cai, Shuyao; Huang, Huijie

    2011-12-01

    An optical detecting technique to identify bio-aerosol particles is proposed in this paper by normalized fluorescence value which correlates to its size and intrinsic fluorescence. With the bio-aerosol detecting system developed, we test and analyze three types of aerosols, while each of them contains fluorescent microspheres of a certain size. The result indicates that different fluorescent microspheres containing the same fluorescent substances have the same normalized fluorescence voltage to unit particle size in diameter. The normalized fluorescence value of other species aerosols is tested for comparing. The research results can be applied to identification of bio-aerosols preliminarily.

  4. The spatial distribution of mineral dust and its shortwave radiative forcing over North Africa. Modeling sensitivities to dust emissions and aerosol size treatments

    SciTech Connect

    Zhao, Chun; Liu, Xiaohong; Leung, Lai-Yung R.; Johnson, Ben; McFarlane, Sally A.; Gustafson, William I.; Fast, Jerome D.; Easter, Richard C.

    2010-09-20

    A fully coupled meteorology-chemistry-aerosol model (WRF-Chem) with the implementation of two dust emission schemes (GOCART and DUSTRAN) into two aerosol models (MADE/SORGAM and MOSAIC) is applied over North Africa to investigate the modeling sensitivities to dust emissions and aerosol size treatments in simulating mineral dust and its shortwave (SW) radiative forcing. Model results of the spatial distribution of mineral dust and its radiative forcing are evaluated using measurements from the AMMA SOP0 campaign in January and February of 2006 over North Africa. Our study suggests that the size distribution of emitted dust can result in significant differences (up to 100%) in simulating mineral dust and its SW radiative forcing. With the same dust emission and dry deposition processes, two aerosol models, MADE/SORGAM and MOSAIC, can yield large difference in size distributions of dust particles due to their different aerosol size treatments using modal and sectional approaches respectively. However, the difference between the two aerosol models in simulating the mass concentrations and the SW radiative forcing of mineral dust is small (< 10%). The model simulations show that mineral dust increases AOD by a factor of 2, heats the lower atmosphere (1-3 km) with a maximum rate of 0.7±0.5 K day-1 below 1 km, and reduces the downwelling SW radiation by up to 25 W m-2 on 24-hour average at surface, highlighting the importance of including dust radiative impact in understanding the regional climate of North Africa. When compared to the available measurements, WRF-Chem simulations can generally capture the measured features of mineral dust and its radiative properties over North Africa, suggesting that the model can be used to perform more extensive simulations of regional climate over North Africa.

  5. Mars aerosol studies with the MGS TES emission phase function observations: Optical depths, particle sizes, and ice cloud types versus latitude and solar longitude

    NASA Astrophysics Data System (ADS)

    Clancy, R. Todd; Wolff, Michael J.; Christensen, Philip R.

    2003-09-01

    Emission phase function (EPF) observations taken in 1999-2001 by Mars Global Surveyor Thermal Emission Spectrometer (MGS TES) support the broadest study of Martian aerosol properties to date. TES solar band and infrared (IR) spectral EPF sequences are analyzed to obtain first-time seasonal/latitudinal distributions of visible optical depths, particle sizes, and single scattering phase functions. This combined angular and wavelength coverage enables identification of two distinct ice cloud types over 45°S-45°N. Type 1 ice clouds exhibit small particle sizes (reff = 1-2 μm) and a distinctive backscattering increase. They are most prevalent in the southern hemisphere during aphelion, but also appear more widely distributed in season and latitude as topographic and high-altitude (>=20 km) ice hazes. Type 2 ice clouds exhibit larger particle sizes (reff = 3-4 μm), a distinct side-scattering minimum at 90-100° phase angles (characteristic of a change in particle shape relative to the type 1), and appear most prominently in the northern subtropical aphelion cloud belt. The majority of retrieved dust visible-to-IR optical depth ratios are indicative of reff = 1.5 +/- 0.1 μm, consistent with Pathfinder and Viking/Mariner 9 reanalyses. However, increased ratios (2.7 versus 1.7) appear frequently in the northern hemisphere over LS = 50-200°, indicating substantially smaller dust particles sizes (reff = 1.0 +/- 0.2 μm) at this time. In addition, larger (reff = 1.8-2.5 μm) dust particles were observed locally in the southern hemisphere during the peak of the 2001 global dust storm. Detailed spectral modeling of the TES visible band pass indicates agreement of EPF-derived dust single scattering albedos (0.92-0.94) with the spectrally resolved results from Pathfinder observations.

  6. Near real time vapor detection and enhancement using aerosol adsorption

    DOEpatents

    Novick, V.J.; Johnson, S.A.

    1999-08-03

    A vapor sample detection method is described where the vapor sample contains vapor and ambient air and surrounding natural background particles. The vapor sample detection method includes the steps of generating a supply of aerosol that have a particular effective median particle size, mixing the aerosol with the vapor sample forming aerosol and adsorbed vapor suspended in an air stream, impacting the suspended aerosol and adsorbed vapor upon a reflecting element, alternatively directing infrared light to the impacted aerosol and adsorbed vapor, detecting and analyzing the alternatively directed infrared light in essentially real time using a spectrometer and a microcomputer and identifying the vapor sample. 13 figs.

  7. Near real time vapor detection and enhancement using aerosol adsorption

    DOEpatents

    Novick, Vincent J.; Johnson, Stanley A.

    1999-01-01

    A vapor sample detection method where the vapor sample contains vapor and ambient air and surrounding natural background particles. The vapor sample detection method includes the steps of generating a supply of aerosol that have a particular effective median particle size, mixing the aerosol with the vapor sample forming aerosol and adsorbed vapor suspended in an air stream, impacting the suspended aerosol and adsorbed vapor upon a reflecting element, alternatively directing infrared light to the impacted aerosol and adsorbed vapor, detecting and analyzing the alternatively directed infrared light in essentially real time using a spectrometer and a microcomputer and identifying the vapor sample.

  8. Investigating Chemical and Thermodynamic Conditions that Determine the Aerosol Inorganic Nitrate Size Distribution: Insights from Speciated PM2.5 and PM10 Hourly Datasets from an Urban Site

    NASA Astrophysics Data System (ADS)

    Griffith, S. M.; Huang, X. H. H.; Louie, P. K. K.; Yu, J. Z.

    2015-12-01

    Nitric acid (HNO3), the gas-phase precursor to aerosol nitrate is known to rapidly transfer to aerosols where NH4+ is in excess to SO42- present in the aerosol, but the HNO3 is also subject to the slower uptake onto sea salt and dust laden particles. Understanding the competition between these routes is necessary to predict the NO3- distribution and impact on aerosols. In this study, we investigated the conditions leading to predominant fine or coarse mode aerosol nitrate using an hourly MARGA 2S dataset from an urban site in Hong Kong. The hourly dataset of inorganic ions (SO42-, NH4+, NO3-, Na+, Cl-, Ca2+, K+, Mg2+) in 2 size ranges (fine, < 2.5 μm; fine+coarse, < 10 μm) and water-soluble gases (HNO3, HCl, and NH3) spanning more than 1 year provides a rich trove for analyzing aerosol nitrate chemistry and the underlying mechanisms that ultimately determine the fraction of NO3- in the fine mode. The urban site in this study is initially characterized for seasonal environmental conditions and the aerosol chemical composition. The relationship between excess NH4+ and NO3- in the fine mode is detailed and contrasted with the influence on fine mode NO3- from uptake on sea salt and dust, which is typically relegated as a 'coarse-mode' mechanism. The distribution of NO3- in the fine and coarse modes is compared with the distribution of the other inorganic ions, where sea-salt ion (Na+, Mg2+) distributions yield the highest explained variability for the nitrate distributions. As a complement to that finding, the cation equivalency (excluding NH4+) in the coarse mode proves to be a crucial factor in leveraging the distribution away from fine mode nitrate. The uptake potential of the water-soluble gases is used to drive a mass transfer model and compare with thermodynamic equilibrium results. In the modeling, the partitioning cycles of fine and coarse mode aerosol nitrate highlight the dynamic relationship between NO3- and Cl- in both the fine and coarse modes, where the

  9. The Influence of Wildfires on Aerosol Size Distributions in Rural Areas

    PubMed Central

    Alonso-Blanco, E.; Calvo, A. I.; Fraile, R.; Castro, A.

    2012-01-01

    The number of particles and their size distributions were measured in a rural area, during the summer, using a PCASP-X. The aim was to study the influence of wildfires on particle size distributions. The comparative studies carried out reveal an average increase of around ten times in the number of particles in the fine mode, especially in sizes between 0.10 and 0.14 μm, where the increase is of nearly 20 times. An analysis carried out at three different points in time—before, during, and after the passing of the smoke plume from the wildfires—shows that the mean geometric diameter of the fine mode in the measurements affected by the fire is smaller than the one obtained in the measurements carried out immediately before and after (0.14 μm) and presents average values of 0.11 μm. PMID:22629191

  10. Constraining Aerosol Optical Models Using Ground-Based, Collocated Particle Size and Mass Measurements in Variable Air Mass Regimes During the 7-SEAS/Dongsha Experiment

    NASA Technical Reports Server (NTRS)

    Bell, Shaun W.; Hansell, Richard A.; Chow, Judith C.; Tsay, Si-Chee; Wang, Sheng-Hsiang; Ji, Qiang; Li, Can; Watson, John G.; Khlystov, Andrey

    2012-01-01

    During the spring of 2010, NASA Goddard's COMMIT ground-based mobile laboratory was stationed on Dongsha Island off the southwest coast of Taiwan, in preparation for the upcoming 2012 7-SEAS field campaign. The measurement period offered a unique opportunity for conducting detailed investigations of the optical properties of aerosols associated with different air mass regimes including background maritime and those contaminated by anthropogenic air pollution and mineral dust. What appears to be the first time for this region, a shortwave optical closure experiment for both scattering and absorption was attempted over a 12-day period during which aerosols exhibited the most change. Constraints to the optical model included combined SMPS and APS number concentration data for a continuum of fine and coarse-mode particle sizes up to PM2.5. We also take advantage of an IMPROVE chemical sampler to help constrain aerosol composition and mass partitioning of key elemental species including sea-salt, particulate organic matter, soil, non sea-salt sulphate, nitrate, and elemental carbon. Our results demonstrate that the observed aerosol scattering and absorption for these diverse air masses are reasonably captured by the model, where peak aerosol events and transitions between key aerosols types are evident. Signatures of heavy polluted aerosol composed mostly of ammonium and non sea-salt sulphate mixed with some dust with transitions to background sea-salt conditions are apparent in the absorption data, which is particularly reassuring owing to the large variability in the imaginary component of the refractive indices. Extinctive features at significantly smaller time scales than the one-day sample period of IMPROVE are more difficult to reproduce, as this requires further knowledge concerning the source apportionment of major chemical components in the model. Consistency between the measured and modeled optical parameters serves as an important link for advancing remote

  11. Phase partitioning of soluble trace gases with size-resolved aerosols in near-surface continental air over northern Colorado, USA, during winter

    NASA Astrophysics Data System (ADS)

    Young, Andrew H.; Keene, William C.; Pszenny, Alexander A. P.; Sander, Rolf; Thornton, Joel A.; Riedel, Theran P.; Maben, John R.

    2013-08-01

    During the Nitrogen, Aerosol Composition, and Halogens on a Tall Tower campaign at the National Oceanic and Atmospheric Administration Boulder Atmospheric Observatory tower, Erie, CO, USA, in winter 2011, soluble trace gases, the ionic composition of size-resolved aerosols, and the associated meteorological conditions were measured. Median gas-phase mixing ratios of HCl, HNO3, and NH3 were 0.072, 0.202, and 5.79 nmol mol-1, respectively. Most aerosol Cl- was associated with supermicrometer size fractions whereas NO3- and NH4+ were associated primarily with submicrometer size fractions. Aerosol pHs inferred from the measured phase partitioning and thermodynamic properties of HNO3 and NH3 were similar both in terms of absolute values and variability as a function of size. Aerosols were acidic across all size fractions and throughout the duration of the campaign (mostly in the pH range of 2 to 3). The pHs inferred from the HCl/Cl- couple were consistently higher by about 1 to 2 pH units, suggesting possible bias in the associated thermodynamic evaluation of HCl. Specifically, relative to those for HNO3 and NH3, the Henry's law constant for HCl is associated with much greater uncertainty. Condensation of HCl replaced Cl- consumed in the production of ClNO2. Additionally, total Cl (HCl + Cl-) was greater than ClNO2 in sampled air parcels, suggesting that Cl availability was not the limiting factor in ClNO2 production. Median ClNO2 yields from N2O5 reaction with particulate Cl- associated with all size fractions were greater than 0.9.

  12. Dicarboxylic acids, oxoacids, benzoic acid, α-dicarbonyls, WSOC, OC, and ions in spring aerosols from Okinawa Island in the western North Pacific Rim: size distributions and formation processes

    NASA Astrophysics Data System (ADS)

    Deshmukh, D. K.; Kawamura, K.; Lazaar, M.; Kunwar, B.; Boreddy, S. K. R.

    2015-09-01

    Size-segregated aerosols (9-stages from < 0.43 to > 11.3 μm in diameter) were collected at Cape Hedo, Okinawa in spring 2008 and analyzed for water-soluble diacids (C2-C12), ω-oxoacids (ωC2-ωC9), pyruvic acid, benzoic acid and α-dicarbonyls (C2-C3) as well as water-soluble organic carbon (WSOC), organic carbon (OC) and major ions. In all the size-segregated aerosols, oxalic acid (C2) was found as the most abundant species followed by malonic and succinic acids whereas glyoxylic acid (ωC2) was the dominant oxoacid and glyoxal (Gly) was more abundant than methylglyoxal. Diacids (C2-C5), ωC2 and Gly as well as WSOC and OC peaked at 0.65-1.1 μm in fine mode whereas azelaic (C9) and 9-oxononanoic (ωC9) acids peaked at 3.3-4.7 μm in coarse mode. Sulfate and ammonium are enriched in fine mode whereas sodium and chloride are in coarse mode. These results imply that water-soluble species in the marine aerosols could act as cloud condensation nuclei (CCN) to develop the cloud cover over the western North Pacific Rim. The organic species are likely produced by a combination of gas-phase photooxidation, and aerosol-phase or in-cloud processing during long-range transport. The coarse mode peaks of malonic and succinic acids were obtained in the samples with marine air masses, suggesting that they may be associated with the reaction on sea salt particles. Bimodal size distributions of longer-chain diacid (C9) and oxoacid (ωC9) with a major peak in the coarse mode suggest their production by photooxidation of biogenic unsaturated fatty acids via heterogeneous reactions on sea salt particles.