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Sample records for aerosol size information

  1. Aerosol typing - key information from aerosol studies

    NASA Astrophysics Data System (ADS)

    Mona, Lucia; Kahn, Ralph; Papagiannopoulos, Nikolaos; Holzer-Popp, Thomas; Pappalardo, Gelsomina

    2016-04-01

    Aerosol typing is a key source of aerosol information from ground-based and satellite-borne instruments. Depending on the specific measurement technique, aerosol typing can be used as input for retrievals or represents an output for other applications. Typically aerosol retrievals require some a priori or external aerosol type information. The accuracy of the derived aerosol products strongly depends on the reliability of these assumptions. Different sensors can make use of different aerosol type inputs. A critical review and harmonization of these procedures could significantly reduce related uncertainties. On the other hand, satellite measurements in recent years are providing valuable information about the global distribution of aerosol types, showing for example the main source regions and typical transport paths. Climatological studies of aerosol load at global and regional scales often rely on inferred aerosol type. There is still a high degree of inhomogeneity among satellite aerosol typing schemes, which makes the use different sensor datasets in a consistent way difficult. Knowledge of the 4d aerosol type distribution at these scales is essential for understanding the impact of different aerosol sources on climate, precipitation and air quality. All this information is needed for planning upcoming aerosol emissions policies. The exchange of expertise and the communication among satellite and ground-based measurement communities is fundamental for improving long-term dataset consistency, and for reducing aerosol type distribution uncertainties. Aerosol typing has been recognized as one of its high-priority activities of the AEROSAT (International Satellite Aerosol Science Network, http://aero-sat.org/) initiative. In the AEROSAT framework, a first critical review of aerosol typing procedures has been carried out. The review underlines the high heterogeneity in many aspects: approach, nomenclature, assumed number of components and parameters used for the

  2. 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.

  3. 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.

  4. 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.

  5. 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

  6. Aerosol Size Distribution in the marine regions

    NASA Astrophysics Data System (ADS)

    Markuszewski, Piotr; Petelski, Tomasz; Zielinski, Tymon; Pakszys, Paulina; Strzalkowska, Agata; Makuch, Przemyslaw; Kowalczyk, Jakub

    2014-05-01

    We would like to present the data obtained during the regular research cruises of the S/Y Oceania over a period of time between 2009 - 2012. The Baltic Sea is a very interesting polygon for aerosol measurements, however, also difficult due to the fact that mostly cases of a mixture of continental and marine aerosols are observed. It is possible to measure clear marine aerosol, but also advections of dust from southern Europe or even Africa. This variability of data allows to compare different conditions. The data is also compared with our measurements from the Arctic Seas, which have been made during the ARctic EXperiment (AREX). The Arctic Seas are very suitable for marine aerosol investigations since continental advections of aerosols are far less frequent than in other European sea regions. The aerosol size distribution was measured using the TSI Laser Aerosol Spectrometer model 3340 (99 channels, measurement range 0.09 μm to 7 μm), condensation particle counter (range 0.01 μm to 3 μm) and laser particle counter PMS CSASP-100-HV-SP (range 0.5 μm to 47 μm in 45 channels). Studies of marine aerosol production and transport are important for many Earth sciences such as cloud physics, atmospheric optics, environmental pollution studies and interaction between ocean and atmosphere. All equipment was placed on one of the masts of S/Y Oceania. Measurements using the laser aerosol spectrometer and condensation particle counter were made on one level (8 meters above sea level). Measurements with the laser particle counter were performed at five different levels above the sea level (8, 11, 14, 17 and 20 m). Based on aerosol size distribution the parameterizations with a Log-Normal and a Power-Law distributions were made. The aerosol source functions, characteristic for the region were also determined. Additionally, poor precision of the sea spray emission determination was confirmed while using only the aerosol concentration data. The emission of sea spray depends

  7. Strategy to use the Terra Aerosol Information to Derive the Global Aerosol Radiative Forcing of Climate

    NASA Technical Reports Server (NTRS)

    Kaufman, Yoram J.; Tanre, Didier; Einaudi, Franco (Technical Monitor)

    2000-01-01

    Terra will derive the aerosol optical thickness and properties. The aerosol properties can be used to distinguish between natural and human-made aerosol. In the polar orbit Terra will measure aerosol only once a day, around 10:30 am. How will we use this information to study the global radiative impacts of aerosol on climate? We shall present a strategy to address this problem. It includes the following steps: - From the Terra aerosol optical thickness and size distribution model we derive the effect of aerosol on reflection of solar radiation at the top of the atmosphere. In a sensitivity study we show that the effect of aerosol on solar fluxes can be derived 10 times more accurately from the MODIS data than derivation of the optical thickness itself. Applications to data over several regions will be given. - Using 1/2 million AERONET global data of aerosol spectral optical thickness we show that the aerosol optical thickness and properties during the Terra 10:30 pass are equivalent to the daily average. Due to the aerosol lifetime of several days measurements at this time of the day are enough to assess the daily impact of aerosol on radiation. - Aerosol impact on the top of the atmosphere is only part of the climate question. The INDOEX experiment showed that addressing the impact of aerosol on climate, requires also measurements of the aerosol forcing at the surface. This can be done by a combination of measurements of MODIS and AERONET data.

  8. 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.

  9. 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.

  10. 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.

  11. Black carbon aerosol size in snow.

    PubMed

    Schwarz, J P; Gao, R S; Perring, A E; Spackman, J R; Fahey, D W

    2013-01-01

    The effect of anthropogenic black carbon (BC) aerosol on snow is of enduring interest due to its consequences for climate forcing. Until now, too little attention has been focused on BC's size in snow, an important parameter affecting BC light absorption in snow. Here we present first observations of this parameter, revealing that BC can be shifted to larger sizes in snow than are typically seen in the atmosphere, in part due to the processes associated with BC removal from the atmosphere. Mie theory analysis indicates a corresponding reduction in BC absorption in snow of 40%, making BC size in snow the dominant source of uncertainty in BC's absorption properties for calculations of BC's snow albedo climate forcing. The shift reduces estimated BC global mean snow forcing by 30%, and has scientific implications for our understanding of snow albedo and the processing of atmospheric BC aerosol in snowfall.

  12. Information Content of Aerosol Retrievals in the Sunglint Region

    NASA Technical Reports Server (NTRS)

    Ottaviani, M.; Knobelspiesse, K.; Cairns, B.; Mishchenko, M.

    2013-01-01

    We exploit quantitative metrics to investigate the information content in retrievals of atmospheric aerosol parameters (with a focus on single-scattering albedo), contained in multi-angle and multi-spectral measurements with sufficient dynamical range in the sunglint region. The simulations are performed for two classes of maritime aerosols with optical and microphysical properties compiled from measurements of the Aerosol Robotic Network. The information content is assessed using the inverse formalism and is compared to that deriving from observations not affected by sunglint. We find that there indeed is additional information in measurements containing sunglint, not just for single-scattering albedo, but also for aerosol optical thickness and the complex refractive index of the fine aerosol size mode, although the amount of additional information varies with aerosol type.

  13. Size distribution of ions in atmospheric aerosols

    NASA Astrophysics Data System (ADS)

    Krivácsy, Z.; Molnár, Á.

    The aim of this paper is to present data about the concentration and size distribution of ions in atmospheric aerosol under slightly polluted urban conditions in Hungary. Concentration of inorganic cations (ammonium, sodium, potassium, calcium, magnesium), inorganic anions (sulfate, nitrate, chloride, carbonate) and organic acids (oxalic, malonic, succinic, formic and acetic acid) for 8 particle size range between 0.0625 and 16 μm were determined. As was the case for ammonium, sulfate and nitrate, the organic acids were mostly found in the fine particle size range. Potassium and chloride were rather uniformly distributed between fine and coarse particles. Sodium, calcium, magnesium and carbonate were practically observed in the coarse mode. The results obtained for the summer and the winter half-year were also compared. The mass concentrations were recalculated in equivalents, and the ion balance was found to be reasonable in most cases. Measurement of the pH of the aerosol extracts indicates that the aerosol is acidic in the fine mode, but alkaline in the coarse particle size range.

  14. 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.

  15. 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.

  16. Aerosol size distribution and aerosol water content measurements during Atlantic Stratocumulus Transition Experiment/Marine Aerosol and Gas Exchange

    NASA Astrophysics Data System (ADS)

    Kim, Y.; Sievering, H.; Boatman, J.; Wellman, D.; Pszenny, A.

    1995-11-01

    Aerosol size distribution data measured during the June 1992 Marine Aerosol and Gas Exchange experiment are analyzed to investigate the characteristics of fine marine aerosol particles measured over the North Atlantic near the Azores Islands. Measured aerosol size distribution data were corrected using the corrected size calibration data based on the optical properties of particles being measured. The corrected size distribution data were then approximated with either one or two lognormal size distributions, depending on air mass conditions. Under clean air mass conditions <3 μm diameter aerosol size distributions typically exhibited two modes, consisting of an accumulation mode and the small end of the sea-salt particle mode. However, under the influence of continental polluted air masses, the aerosol size distribution was dominated by <1 μm diameter particles in a single mode with an increased aerosol concentration. Aerosol water content of accumulation mode marine aerosols was estimated from differences between several series of ambient and dried aerosol size distributions. The average aerosol water fraction was 0.31, which is in good agreement with an empirical aerosol growth model estimate. The average rate of SO4= production in the accumulation mode aerosol water by H2O2 oxidation was estimated to be <7×10-10 mol L-1 s-1, which is an insignificant contributor to the observed non-sea-salt SO4= in the accumulation mode.

  17. 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.

  18. Fog-Influenced Submicron Aerosol Number Size Distributions

    NASA Astrophysics Data System (ADS)

    Zikova, N.; Zdimal, V.

    2013-12-01

    The aim of this work is to evaluate the influence of fog on aerosol particle number size distributions (PNSD) in submicron range. Thus, five-year continuous time series of the SMPS (Scanning Mobility Particle Sizer) data giving information on PNSD in five minute time step were compared with detailed meteorological records from the professional meteorological station Kosetice in the Czech Republic. The comparison included total number concentration and PNSD in size ranges between 10 and 800 nm. The meteorological records consist from the exact times of starts and ends of individual meteorological phenomena (with one minute precision). The records longer than 90 minutes were considered, and corresponding SMPS spectra were evaluated. Evaluation of total number distributions showed considerably lower concentration during fog periods compared to the period when no meteorological phenomenon was recorded. It was even lower than average concentration during presence of hydrometeors (not only fog, but rain, drizzle, snow etc. as well). Typical PNSD computed from all the data recorded in the five years is in Figure 1. Not only median and 1st and 3rd quartiles are depicted, but also 5th and 95th percentiles are plotted, to see the variability of the concentrations in individual size bins. The most prevailing feature is the accumulation mode, which seems to be least influenced by the fog presence. On the contrary, the smallest aerosol particles (diameter under 40 nm) are effectively removed, as well as the largest particles (diameter over 500 nm). Acknowledgements: This work was supported by the projects GAUK 62213 and SVV-2013-267308. Figure 1. 5th, 25th, 50th, 75th and 95th percentile of aerosol particle number size distributions recorded during fog events.

  19. 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

  20. Nano-sized aerosol classification, collection and analysis--method development using dental composite materials.

    PubMed

    Bogdan, Axel; Buckett, Mary I; Japuntich, Daniel A

    2014-01-01

    This article presents a methodical approach for generating, collecting, and analyzing nano-size (1-100 nm) aerosol from abraded dental composite materials. Existing aerosol sampling instruments were combined with a custom-made sampling chamber to create and sample a fresh, steady-state aerosol size distribution before significant Brownian coagulation. Morphological, size, and compositional information was obtained by Transmission Electron Microscopy (TEM). To create samples sizes suitable for TEM analysis, aerosol concentrations in the test chamber had to be much higher than one would typically expect in a dental office, and therefore, these results do not represent patient or dental personnel exposures. Results show that nano-size aerosol was produced by the dental drill alone, with and without cooling water drip, prior to abrasion of dental composite. During abrasion, aerosol generation seemed independent of the percent filler load of the restorative material and the operator who generated the test aerosol. TEM investigation showed that "chunks" of filler and resin were generated in the nano-size range; however, free nano-size filler particles were not observed. The majority of observed particles consisted of oil droplets, ash, and graphitic structures.

  1. 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.

  2. 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.

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

    DOE PAGES

    Zhang, Y.; Easter, R. C.; Ghan, S. J.; ...

    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

  4. 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).

  5. Aerosol effects on deep convective clouds: impact of changes in aerosol size distribution and aerosol activation parameterization

    NASA Astrophysics Data System (ADS)

    Ekman, A. M. L.; Engström, A.; Söderberg, A.

    2010-03-01

    A cloud-resolving model including explicit aerosol physics and chemistry is used to study the impact of aerosols on deep convective strength. More specifically, by conducting six sensitivity series we examine how the complexity of the aerosol model, the size of the aerosols and the aerosol activation parameterization influence the aerosol-induced deep convective cloud sensitivity. Only aerosol effects on liquid droplet formation are considered. We find that an increased aerosol concentration generally results in stronger convection, which for the simulated case is in agreement with the conceptual model presented by Rosenfeld et al. (2008). However, there are two sensitivity series that do not display a monotonic increase in updraft velocity with increasing aerosol concentration. These exceptions illustrate the need to: 1) account for changes in evaporation processes and subsequent cooling when assessing aerosol effects on deep convective strength, 2) better understand graupel impaction scavenging of aerosols which may limit the number of CCN at a critical stage of cloud development and thereby dampen the convection, 3) increase our knowledge of aerosol recycling due to evaporation of cloud droplets. Furthermore, we find a significant difference in the aerosol-induced deep convective cloud sensitivity when using different complexities of the aerosol model and different aerosol activation parameterizations. For the simulated case, a 100% increase in aerosol concentration results in a difference in average updraft between the various sensitivity series which is as large as the average updraft increase itself. The model simulations also show that the change in graupel and rain formation is not necessarily directly proportional to the change in updraft velocity. For example, several of the sensitivity series display a decrease of the rain amount at the lowest model level with increasing updraft velocity. Finally, an increased number of aerosols in the Aitken mode (here

  6. Stratospheric Aerosols: The Transfer of Scientific Information.

    ERIC Educational Resources Information Center

    Feidler, Anita; Hurt, C. D.

    1986-01-01

    Examines information transfer in atmospheric physics by tracing one paper through five years of citations and suggesting patterns for highly cited papers. The results are also discussed in terms of information transfer in a popularized environment, as stratospheric aerosols have been prominently discussed in the popular press. (Author/EM)

  7. 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.

  8. Measurement of size distributions of a coagulating aerosol. [Calcium carbonate

    SciTech Connect

    Loos, H.G.

    1984-05-01

    Measurements have been performed for the determination of the size distribution of a coagulating ultrafine aerosol over a time interval of up to about 30 min. The aerosol was contained in a balloon with an initial volume of 60 l subject to a temperature inversion for the purpose of quenching the free convection and thereby diminishing the aerosol loss to the balloon wall. The aerosol size distribution was measured with the TSI electrostatic aerosol classifier hooked up to a TSI aerosol electrometer. The initial aerosol had an average diameter of about 12 nm. Measurements were taken by computer at a rate of 1 measurement cycle every 3 s; 1 cycle consists of a measurement of time, and burst measurements of electrometer current, classifier rod voltage, 3 flow rates, and 5 temperatures, followed by the calculation of averages and standard deviations, and storage of the results in a data string. The TSI instruments have been modified to permit the automatic computer reading of the parameters mentioned above. A multiplexer has been built to allow the multiplet data to be measured by a single system voltmeter. Channel switching in the multiplexer can be done either automatically by using the ''delay'' signal emitted by the system voltmeter every time it makes a reading or by software control through the 16-bit parallel interface of the computer.

  9. Size analysis of suspension inhalation aerosols by inertial separation methods.

    PubMed

    Hallworth, G W; Andrews, U G

    1976-12-01

    The particle size distribution of beclomethasone dipropionate (BDP) aerosols delivered from pressurized metered dose suspension inhalers has been measured with three cascaded inertial separation instruments, the Casella Cascade Impactor, Multistage Liquid Impinger and Cascade Centripeter. Various methods for collecting the emitted aerosol before measurement have been examined. A bent glass tubular 'throat', used as a simulated oro-pharynx, collects 35-60% of the emitted dose by impingement of the wet spray cone in the throat. The aerosol passing through the throat has a similar but somewhat finer size distribution to that collected by firing directly into a large flask. The three cascaded instruments give similar results which in the Multistage Liquid Impinger also resemble those given by a salbutamol inhaler. The mass fraction (35-60%) emitted from the oral adaptor which is of a size capable of deep lung penetration ( less than 4 mum) is much higher than the fraction (10-16%) found in the lungs of dogs after inhalation of aerosol. The size distributions resemble those determined by microscopy and are expressed as aerodynamic sizes, thus showing that the particles approximate to unit density spheres. The performance of two simpler devices, Kirk's apparatus and the Harwell size selective air sampler are also assessed, the latter shows some promise for the simple evaluation of the respirable fraction of inhalation aerosols.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. Size and concentration measurement of an industrial aerosol

    SciTech Connect

    O'Brien, D.; Baron, P.; Willeke, K.

    1986-07-01

    Several real-time particle sizing instruments were evaluated for measuring the size distribution and concentration of the aerosol produced during the high speed grinding of gray iron castings. Aerosol was sampled in the airstream entrained by the motion of a spinning grinding wheel in a pilot grinding operation. Measurement methods based on differing physical principles were selected for evaluation and compared: particle inertia (aerodynamic particle sizer and quartz crystal microbalance cascade impactor); light scattering (laser aerosol spectrometer); and projected-area microscopy (scanning electron microscope). Inferences of aerodynamic diameter based on measurements by the laser aerosol spectrometer consistently undersized that determined by the aerodynamic particle sizer by a factor of 1.5. Estimates of aerodynamic diameters from projected area diameters determined by scanning electron microscopy differed from those obtained by the aerodynamic particle sizer by a factor of 2. Differences appeared to be a non-linear function of particle diameter. Estimates of respirable mass determined from mass-weighted particle size spectra varied by a factor of 6 between the largest estimate (scanning electron microscope) and the smallest estimate (laser aerosol spectrometer).

  15. Size and concentration measurement of an industrial aerosol.

    PubMed

    O'Brien, D; Baron, P; Willeke, K

    1986-07-01

    Several real-time particle sizing instruments were evaluated for measuring the size distribution and concentration of the aerosol produced during the high speed grinding of gray iron castings. Aerosol was sampled in the airstream entrained by the motion of a spinning grinding wheel in a pilot grinding operation. Measurement methods based on differing physical principles were selected for evaluation and compared: particle inertia (aerodynamic particle sizer and quartz crystal microbalance cascade impactor); light scattering (laser aerosol spectrometer); and projected-area microscopy (scanning electron microscope). Inferences of aerodynamic diameter based on measurements by the laser aerosol spectrometer consistently undersized that determined by the aerodynamic particle sizer by a factor of 1.5. Estimates of aerodynamic diameters from projected area diameters determined by scanning electron microscopy differed from those obtained by the aerodynamic particle sizer by a factor of 2. Differences appeared to be a non-linear function of particle diameter. Estimates of respirable mass determined from mass-weighted particle size spectra varied by a factor of 6 between the largest estimate (scanning electron microscope) and the smallest estimate (laser aerosol spectrometer).

  16. 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.

  17. Airborne Measurements of Aerosol Size Distributions During PACDEX

    NASA Astrophysics Data System (ADS)

    Rogers, D. C.; Gandrud, B.; Campos, T.; Kok, G.; Stith, J.

    2007-12-01

    The Pacific Dust Experiment (PACDEX) is an airborne project that attempts to characterize the indirect aerosol effect by tracing plumes of dust and pollution across the Pacific Ocean. This project occurred during April-May 2007 and used the NSF/NCAR HIAPER research aircraft. When a period of strong generation of dust particles and pollution was detected by ground-based and satellite sensors, then the aircraft was launched from Colorado to Alaska, Hawaii, and Japan. Its mission was to intercept and track these plumes from Asia, across the Pacific Ocean, and ultimately to the edges of North America. For more description, see the abstract by Stith and Ramanathan (this conference) and other companion papers on PACDEX. The HIAPER aircraft carried a wide variety of sensors for measuring aerosols, cloud particles, trace gases, and radiation. Sampling was made in several weather regimes, including clean "background" air, dust and pollution plumes, and regions with cloud systems. Altitude ranges extended from 100 m above the ocean to 13.4 km. This paper reports on aerosol measurements made with a new Ultra-High Sensitivity Aerosol Spectrometer (UHSAS), a Radial Differential Mobility Analyzer (RDMA), a water-based CN counter, and a Cloud Droplet Probe (CDP). These cover the size range 10 nm to 10 um diameter. In clear air, dust was detected with the UHSAS and CDP. Polluted air was identified with high concentrations of carbon monoxide, ozone, and CN. Aerosol size distributions will be presented, along with data to define the context of weather regimes.

  18. A model for predicting fog aerosol size distributions

    NASA Astrophysics Data System (ADS)

    Rudiger, Joshua J.; Book, Kevin; Baker, Brooke; deGrassie, John Stephen; Hammel, Stephen

    2016-09-01

    An accurate model and parameterization of fog is needed to increase the reliability and usefulness of electro-optical systems in all relevant environments. Current models vary widely in their ability to accurately predict the size distribution and subsequent optical properties of fog. The Advanced Navy Aerosol Model (ANAM), developed to model the distribution of aerosols in the maritime environment, does not currently include a model for fog. One of the more prevalent methods for modeling particle size spectra consists of fitting a modified gamma function to fog measurement data. This limits the fog distribution to a single mode. Here we establish an empirical model for predicting complicated multimodal fog droplet size spectra using machine learning techniques. This is accomplished through careful measurements of fog in a controlled laboratory environment and measuring fog particle size distributions during outdoor fog events.

  19. 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...

  20. Measurement and Modeling Results on the Evolution of Aerosol Size Distributions in the Tropics

    NASA Astrophysics Data System (ADS)

    Bahreini, R.; Kazil, J.; Reeves, J. M.; Froyd, K. D.; Wilson, J. C.

    2012-12-01

    Aerosol particles in the upper troposphere-lower stratosphere (UTLS) affect local chemistry and radiation balance due to their role in heterogeneous reactions and contribution to light scattering. Tropical UTLS particles also act as a source of lower stratospheric aerosol populations in the mid-latitudes. Therefore, understanding the processes controlling evolution of the particles in the tropical UTLS is of great importance. We present measurements of aerosol size distributions (4-1000 nm) in the tropics during winter (Pre-AVE, 2004 and CRAVE, 2006) and summer (TC4, 2007), using NMASS (Nuclei Mode Aerosol Size Spectrometer) and FCAS (Focused Cavity Aerosol Spectrometer) instruments aboard the NASA WB-57 aircraft. At altitudes below the tropical tropopause layer (TTL), integrated number and volume distributions indicate a factor of 2-5 variability between 2004 and 2006, reflecting the influence of different air mass origins on the local aerosol population. However, above TTL, the distributions are unified, without a significant change between the two years. Furthermore, above the TTL, number fraction of nucleation mode particles decreases from up to 90% to <40% while total aerosol volume and the volume fraction of particles larger than 350 nm increase. We use an aerosol dynamic model (MAIA, Kazil et al. (2007), Weigel et al. (2011)), constrained by observations to account for the horizontal air mass mixing from mid-latitudes, to simulate aerosol evolution in the tropical UTLS. We will discuss the results of MAIA's sensitivity runs along with the available aerosol composition information to gain insight into the processes controlling the increase in aerosol volume above the TTL. We will also use 2007 observations and MAIA's model results to compare winter-summer aerosol growth processes in the tropical UTLS. Kazil, J., et al., Is aerosol formation in cirrus clouds possible?, Atmos. Chem. Phys., 7, 1407-1413, doi:10.5194/acp-7-1407-2007, 2007. Weigel et al., In situ

  1. Size dependence of phase transitions in aerosol nanoparticles

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

    Phase transitions of nanoparticles are of fundamental importance in atmospheric sciences. 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. Our analysis reveals that particle size can strongly alter the characteristic concentration of phase separation in mixed systems, resembling the influence of temperature. Due 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. Reference: Cheng, Y. et al. Size dependence of phase transitions in aerosol nanoparticles. Nature Communications. 5:5923 doi: 10.1038/ncomms6850 (2015).

  2. 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...

  3. 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.

  4. 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

  5. Mass size distributions of elemental aerosols in industrial area.

    PubMed

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

    2015-11-01

    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 m(3)/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/m(3) (for Ba) to 89.62 ng/m(3) (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.

  6. Aerosol size distribution at Nansen Ice Sheet Antarctica

    NASA Astrophysics Data System (ADS)

    Belosi, F.; Contini, D.; Donateo, A.; Santachiara, G.; Prodi, F.

    2012-04-01

    During austral summer 2006, in the framework of the XXII Italian Antarctic expedition of PNRA (Italian National Program for Research in Antarctica), aerosol particle number size distribution measurements were performed in the 10-500 range nm over the Nansen Ice Sheet glacier (NIS, 74°30' S, 163°27' E; 85 m a.s.l), a permanently iced branch of the Ross Sea. Observed total particle number concentrations varied between 169 and 1385 cm- 3. A monomodal number size distribution, peaking at about 70 nm with no variation during the day, was observed for continental air mass, high wind speed and low relative humidity. Trimodal number size distributions were also observed, in agreement with measurements performed at Aboa station, which is located on the opposite side of the Antarctic continent to the NIS. In this case new particle formation, with subsequent particle growth up to about 30 nm, was observed even if not associated with maritime air masses.

  7. 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.

  8. Informing Aerosol Transport Models With Satellite Multi-Angle Aerosol Measurements

    NASA Technical Reports Server (NTRS)

    Limbacher, J.; Patadia, F.; Petrenko, M.; Martin, M. Val; Chin, M.; Gaitley, B.; Garay, M.; Kalashnikova, O.; Nelson, D.; Scollo, S.

    2011-01-01

    As the aerosol products from the NASA Earth Observing System's Multi-angle Imaging SpectroRadiometer (MISR) mature, we are placing greater focus on ways of using the aerosol amount and type data products, and aerosol plume heights, to constrain aerosol transport models. We have demonstrated the ability to map aerosol air-mass-types regionally, and have identified product upgrades required to apply them globally, including the need for a quality flag indicating the aerosol type information content, that varies depending upon retrieval conditions. We have shown that MISR aerosol type can distinguish smoke from dust, volcanic ash from sulfate and water particles, and can identify qualitative differences in mixtures of smoke, dust, and pollution aerosol components in urban settings. We demonstrated the use of stereo imaging to map smoke, dust, and volcanic effluent plume injection height, and the combination of MISR and MODIS aerosol optical depth maps to constrain wildfire smoke source strength. This talk will briefly highlight where we stand on these application, with emphasis on the steps we are taking toward applying the capabilities toward constraining aerosol transport models, planet-wide.

  9. Coarse atmospheric aerosol: size distributions of trace elements

    NASA Astrophysics Data System (ADS)

    Eleftheriadis, K.; Colbeck, I.

    A sampler, employing nine single stage impactors placed in parallel within a portable wind tunnel, has been used to determine the metal content of coarse atmospheric aerosol. The wind tunnel maintains a constant flow environment for the collectors housed inside it, so that representative sampling conditions are achieved compared to the varied ambient wind conditions. At a flow rate of 8 m s -1 the 50% cut-off diameters of the impactors ranged from 7.8 to 38.8 μm. Measurements were conducted at a rural and urban site near Colchester in south east England. The samplers were analysed by PIXE for P, K, Ca, Fe, Ti, Mn, Cu, V, Co, Cr, Br, Zn, Ni, Sc and Pb. It is found that the sampler can be employed to quantitatively characterise the elemental mass size distribution for aerosol larger than 10 μm. The results indicate that a small fraction of the above earth and trace elements' metal mass is present in particles greater than 10 μm. This fraction for earth metals (Ca, K, Ti) is comparatively greater in the rural site than the urban site, while for trace metals (Mn, V, Cu, Cr) this fraction constitutes a more significant part of the coarse mass at the urban site. Trace element concentrations were of a similar order of magnitude to earlier literature reports. Although the number of measurements was limited it can be concluded that the size distributions obtained were characteristic of an unpolluted area.

  10. 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

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

    SciTech Connect

    Novick, Vincent J.

    1997-12-01

    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.

  12. 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.

  13. 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

  14. Laser velocimeter seed particle sizing by the whisker particle collector and laser aerosol spectrometer methods

    NASA Astrophysics Data System (ADS)

    Crosswy, F. L.; Kingery, M. K.; Schaefer, H. J.; Pfeifer, H. J.

    1989-07-01

    Two different aerosol particle sizing systems, the Whisker Particle Collector (WPC) and the Laser Aerosol Spectrometer (LAS), were evaluated for sizing aerosol particles in the size range of 0.1 to 3.0 micrometers. The evaluation tests were conducted using an aerosol of alumina (Al2O3) particles, an aerosol commonly used to provide light scattering particles for laser velocimeter measurements in high temperature flows. The LAS and WPC measurements were then compared for samples taken from the alumina particle aerosols. Some difficulty was encountered in directly comparing these measurements. Other operational aspects of the two systems were also compared including on-line/off-line data presentation capabilities, field portability and measurement limitations at the small particle end of the size range of interest.

  15. Aerosol indirect effect from turbulence-induced broadening of cloud-droplet size distributions.

    PubMed

    Chandrakar, Kamal Kant; Cantrell, Will; Chang, Kelken; Ciochetto, David; Niedermeier, Dennis; Ovchinnikov, Mikhail; Shaw, Raymond A; Yang, Fan

    2016-12-13

    The influence of aerosol concentration on the cloud-droplet size distribution is investigated in a laboratory chamber that enables turbulent cloud formation through moist convection. The experiments allow steady-state microphysics to be achieved, with aerosol input balanced by cloud-droplet growth and fallout. As aerosol concentration is increased, the cloud-droplet mean diameter decreases, as expected, but the width of the size distribution also decreases sharply. The aerosol input allows for cloud generation in the limiting regimes of fast microphysics ([Formula: see text]) for high aerosol concentration, and slow microphysics ([Formula: see text]) for low aerosol concentration; here, [Formula: see text] is the phase-relaxation time and [Formula: see text] is the turbulence-correlation time. The increase in the width of the droplet size distribution for the low aerosol limit is consistent with larger variability of supersaturation due to the slow microphysical response. A stochastic differential equation for supersaturation predicts that the standard deviation of the squared droplet radius should increase linearly with a system time scale defined as [Formula: see text], and the measurements are in excellent agreement with this finding. The result underscores the importance of droplet size dispersion for aerosol indirect effects: increasing aerosol concentration changes the albedo and suppresses precipitation formation not only through reduction of the mean droplet diameter but also by narrowing of the droplet size distribution due to reduced supersaturation fluctuations. Supersaturation fluctuations in the low aerosol/slow microphysics limit are likely of leading importance for precipitation formation.

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

    NASA Astrophysics Data System (ADS)

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

    1994-05-01

    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°, 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 size distribution, based on the spectral dependence of the optical thickness, a, cannot estimate accurately the phase function (up to 50% error for λ = 0.87 μm). Before the Pinatubo eruption the ratio between the volumes of sulfate and coarse particles was very well correlated with α. 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 distributions before the injection of stratospheric aerosol consistently show two modes, sulfate particles with rm

  17. 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

  18. 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.

  19. 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

  20. 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

  1. 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.

  2. Real Time Detection of Sodium in Size-Segregated Marine Aerosols

    DTIC Science & Technology

    2002-09-30

    Real Time Measurement of Sea- Salt Aerosol during the SEAS Campaign: Comparison of Emission based Sodium Detection with an Aerosol Volatility Technique. Submitted to the Journal of Atmospheric and Oceanic Technology. ...Real Time Detection of Sodium in Size-Segregated Marine Aerosols Anthony J. Hynes Rosenstiel School of Marine and Atmospheric Science 4600...this capability for sodium and a prototype has been deployed as part of an ONR-sponsored field campaign (SEAS). The ultimate goal of the project is to

  3. 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.

  4. Size-resolved aerosol composition and its link to hygroscopicity at a forested site in Colorado

    NASA Astrophysics Data System (ADS)

    Levin, E. J. T.; Prenni, A. J.; Palm, B. B.; Day, D. A.; Campuzano-Jost, P.; Winkler, P. M.; Kreidenweis, S. M.; DeMott, P. J.; Jimenez, J. L.; Smith, J. N.

    2014-03-01

    Aerosol hygroscopicity describes the ability of a particle to take up water and form a cloud droplet. Modeling studies have shown sensitivity of precipitation-producing cloud systems to the availability of aerosol particles capable of serving as cloud condensation nuclei (CCN), and hygroscopicity is a key parameter controlling the number of available CCN. Continental aerosol is typically assumed to have a representative hygroscopicity parameter, κ, of 0.3; however, in remote locations this value can be lower due to relatively large mass fractions of organic components. To further our understanding of aerosol properties in remote areas, we measured size-resolved aerosol chemical composition and hygroscopicity in a forested, mountainous site in Colorado during the six-week BEACHON-RoMBAS (Bio-hydro-atmosphere interactions of Energy, Aerosols, Carbon, H2O, Organics and Nitrogen-Rocky Mountain Biogenic Aerosol Study) campaign. This campaign followed a year-long measurement period at this site, and results from the intensive campaign shed light on the previously reported seasonal cycle in aerosol hygroscopicity. New particle formation events were observed routinely at this site and nucleation mode composition measurements indicated that the newly formed particles were predominantly organic. These events likely contribute to the dominance of organic species at smaller sizes, where aerosol organic mass fractions were between 70 and 90%. Corresponding aerosol hygroscopicity was observed to be in the range κ = 0.15-0.22, with hygroscopicity increasing with particle size. Aerosol chemical composition measured by an aerosol mass spectrometer and calculated from hygroscopicity measurements agreed very well during the intensive study, with an assumed value of κorg = 0.13 resulting in the best agreement.

  5. MATRIX-ASSISTED LASER DESORPTION IONIZATION OF SIZE AND COMPOSITION SELECTED AEROSOL PARTICLES. (R823980)

    EPA Science Inventory

    Matrix-assisted laser desorption/ionization (MALDI) was performed on individual,
    size-selected aerosol particles in the 2-8 mu m diameter range, Monodisperse aerosol droplets
    containing matrix, analyte, and solvent were generated and entrained in a dry stream of air, The dr...

  6. Aerosol indirect effect from turbulence-induced broadening of cloud-droplet size distributions

    SciTech Connect

    Chandrakar, Kamal Kant; Cantrell, Will; Chang, Kelken; Ciochetto, David; Niedermeier, Dennis; Ovchinnikov, Mikhail; Shaw, Raymond A.; Yang, Fan

    2016-11-28

    The influence of aerosol concentration on cloud droplet size distribution is investigated in a laboratory chamber that enables turbulent cloud formation through moist convection. The experiments allow steady-state microphysics to be achieved, with aerosol input balanced by cloud droplet growth and fallout. As aerosol concentration is increased the cloud droplet mean diameter decreases as expected, but the width of the size distribution also decreases sharply. The aerosol input allows for cloud generation in the limiting regimes of fast microphysics (τc < τt) for high aerosol concentration, and slow microphysics (τc > τt) for low aerosol concentration; here, τc is the phase relaxation time and τt is the turbulence correlation time. The increase in the width of the droplet size distribution for the low aerosol limit is consistent with larger variability of supersaturation due to the slow microphysical response. A stochastic differential equation for supersaturation predicts that the standard deviation of the squared droplet radius should increase linearly with a system time scale defined as τs-1c-1 + τt-1, and the measurements are in excellent agreement with this finding. This finding underscores the importance of droplet size dispersion for the aerosol indirect effect: increasing aerosol concentration not only suppresses precipitation formation through reduction of the mean droplet diameter, but perhaps more importantly, through narrowing of the droplet size distribution due to reduced supersaturation fluctuations. Supersaturation fluctuations in the low aerosol / slow microphysics limit are likely of leading importance for precipitation formation.

  7. 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...

  8. 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

    particles penetrates from outside to inside. Observed isotope ratio depletion indicates that information about aerosol sources can be lost if measurements are performed only inside house. Using carbon and nitrogen isotope ratios data set, we were able to identify and distinguish main aerosol sources (traffic, heating activities) and penetration of aerosol particles from outdoor to indoor. Acknowledgment This work was supported by Research Council of Lithuania under grant "Pollution Control in Biomass Combustion: from Pollutant Formation to Human Exposure" (BioMassPoll), Project no. ATE05/2012. EPA Ireland is acknowledged for the fellowship grant of D. Ceburnis 1. Garbaras, A. Masalaite, I. Garbariene, D. Ceburnis, E. Krugly V. Remeikis, E. Puida K. Kvietkus, D. Martuzevicius, Stable carbon fractionation in size-segregated aerosol particles produced by controlled biomass burning, Journal of Aerosol Science, Vol. 79, p. 86-96 (2015); 2. D. Ceburnis, A. Garbaras, S. Szidat, M. Rinaldi, S. Fahrni, N. Perron, L. Wacker, S. Leinert, V. Remeikis, M. C. Facchini, A. S. H. Prevot, S. G. Jennings, and C. D. O'Dowd, Quantification of the carbonaceous matter origin in submicron marine aerosol particles by dual carbon isotope analysis, Atmospheric Chemistry and Physics, Vol 11, pp. 8593-8606 (2011); 3. V. Ulevicius, S. Bycenkiene, V. Remeikis, A. Garbaras, S. Kecorius, J. Andriejauskiene, D. Jasineviciene, G. Mocnik, Characterization of pollution events in the East Baltic region affected by regional biomass fire emissions, Atmospheric Research, Vol. 98 (2-4), pp. 190-200 (2010).

  9. 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

  10. Atmospheric Black Carbon: Chemical Bonding and Structural Information of Individual Aerosol Particles

    NASA Astrophysics Data System (ADS)

    Gilles, M. K.; Tivanski, A. V.; Hopkins, R. J.; Marten, B. D.

    2006-12-01

    study the interfacial region of tar ball particles collected during a biomass burn event. Examination of the carbonyl functional group intensity, as determined from NEXAFS spectra, with particle size has enabled the presence of a thin oxygenated surface layer to be elucidated. Using all of this information, we assess the suitability of the various BC SRMs and HULIS as standards for anthropogenic combustion and biomass burn atmospheric aerosol.

  11. 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.

  12. Physicochemical Characterization of Capstone Depleted Uranium Aerosols II: Particle Size Distributions as a Function of Time

    SciTech Connect

    Cheng, Yung-Sung; Kenoyer, Judson L.; Guilmette, Raymond A.; Parkhurst, MaryAnn

    2009-03-01

    The Capstone Depleted Uranium (DU) Aerosol Study, which generated and characterized aerosols containing depleted uranium from perforation of armored vehicles with large-caliber DU penetrators, incorporated a sampling protocol to evaluated 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 beta spectrometry, 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 was 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 um and a large size mode between 2 and 15 um. In general, the evolution of particle size over time showed an overall decrease of average particle size from AMADs of 5 to 10 um shortly after perforation to around 1 um at the end of the 2-hr 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.

  13. 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.

  14. Size distribution of chromate paint aerosol generated in a bench-scale spray booth.

    PubMed

    Sabty-Daily, Rania A; Hinds, William C; Froines, John R

    2005-01-01

    Spray painters are potentially exposed to aerosols containing hexavalent chromium [Cr(VI)] via inhalation of chromate-based paint sprays. Evaluating the particle size distribution of a paint spray aerosol, and the variables that may affect this distribution, is necessary to determine the site and degree of respiratory deposition and the damage that may result from inhaled Cr(VI)-containing paint particles. This study examined the effect of spray gun atomization pressure, aerosol generation source and aerosol aging on the size distribution of chromate-based paint overspray aerosols generated in a bench-scale paint spray booth. The study also determined the effect of particle bounce inside a Marple personal cascade impactor on measured size distributions of paint spray aerosols. Marple personal cascade impactors with a modified inlet were used for sample collection. The data indicated that paint particle bounce did not occur inside the cascade impactors sufficiently to affect size distribution when using uncoated stainless steel or PVC substrate sampling media. A decrease in paint aerosol mass median aerodynamic diameter (MMAD) from 8.2 to 7.0 mum was observed as gun atomization pressure increased from 6 to 10 psi. Overspray aerosols were sampled at two locations in the spray booth. A downstream sampling position simulated the exposure of a worker standing between the painted surface and exhaust, a situation encountered in booths with multiple workers. The measured mean MMAD was 7.2 mum. The distance between the painted surface and sampler was varied to sample oversprays of varying ages between 2.8 and 7.7 s. Age was not a significant factor for determining MMAD. Overspray was sampled at a 90 degrees position to simulate a worker standing in front of the surface being painted with air flowing to the worker's side, a common situation in field applications. The resulting overspray MMAD averaged 5.9 mum. Direct-spray aerosols were sampled at ages from 5.3 to 11.7 s

  15. 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

  16. 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

  17. Investigate the relationship between multiwavelength lidar ratios and aerosol size distributions using aerodynamic particle sizer spectrometer

    NASA Astrophysics Data System (ADS)

    Zhao, Hu; Hua, Dengxin; Mao, Jiandong; Zhou, Chunyan

    2017-02-01

    The real aerosol size distributions were obtained by aerodynamic particle sizer spectrometer (APS) in China YinChuan. The lidar ratios at wavelengths of 355 nm, 532 nm and 1064 nm were calculated using Mie theory. The effective radius of aerosol particles reff and volume C/F ratio (coarse/fine) Vc/f were retrieved from the real aerosol size distributions. The relationship between multiwavelength lidar ratios and particle reff and Vc/f were investigated. The results indicate that the lidar ratio is positive correlated to the particle reff and Vc/f. The lidar ratio is more sensitive to the coarse particles. The short wavelength lidar ratio is more sensitive to the particle Vc/f and the long wavelength lidar ratio is more sensitive to the particle reff. The wavelength dependency indicated that the lidar ratios decrease with increasing the wavelength. The lidar ratios are almost irrelevant to the shape and total particles of aerosol size distributions.

  18. Information Content of Bistatic Lidar Observations of Aerosols from Space

    NASA Technical Reports Server (NTRS)

    Alexandrov, Mikhail D.; Mishchenko, Michael I.

    2017-01-01

    We present, for the first time, a quantitative retrieval error-propagation study for a bistatic high spectral resolution lidar (HSRL) system intended for detailed quasi-global monitoring of aerosol properties from space. Our results demonstrate that supplementing a conventional monostatic HSRL with an additional receiver flown in formation at a scattering angle close to 165 degrees dramatically increases the information content of the measurements and allows for a sufficiently accurate characterization of tropospheric aerosols. We conclude that a bistatic HSRL system would far exceed the capabilities of currently flown or planned orbital instruments in monitoring global aerosol effects on the environment and on the Earth's climate. We also demonstrate how the commonly used a priori 'regularization' methodology can artificially reduce the propagated uncertainties and can thereby be misleading as to the real retrieval capabilities of a measurement system.

  19. Information content of bistatic lidar observations of aerosols from space.

    PubMed

    Alexandrov, Mikhail D; Mishchenko, Michael I

    2017-02-20

    We present, for the first time, a quantitative retrieval error-propagation study for a bistatic high spectral resolution lidar (HSRL) system intended for detailed quasi-global monitoring of aerosol properties from space. Our results demonstrate that supplementing a conventional monostatic HSRL with an additional receiver flown in formation at a scattering angle close to 165° dramatically increases the information content of the measurements and allows for a sufficiently accurate characterization of tropospheric aerosols. We conclude that a bistatic HSRL system would far exceed the capabilities of currently flown or planned orbital instruments in monitoring global aerosol effects on the environment and on the Earth's climate. We also demonstrate how the commonly used a priori "regularization" methodology can artificially reduce the propagated uncertainties and can thereby be misleading as to the real retrieval capabilities of a measurement system.

  20. 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.

  1. Influence of particle size and chemistry on the cloud nucleating properties of aerosols

    NASA Astrophysics Data System (ADS)

    Quinn, P. K.; Bates, T. S.; Coffman, D. J.; Covert, D. S.

    2008-02-01

    The ability of an aerosol particle to act as a cloud condensation nuclei (CCN) is a function of the size of the particle, its composition and mixing state, and the supersaturation of the cloud. In-situ data from field studies provide a means to assess the relative importance of these parameters. During the 2006 Texas Air Quality - Gulf of Mexico Atmospheric Composition and Climate Study (TexAQS-GoMACCS), the NOAA RV Ronald H. Brown encountered a wide variety of aerosol types ranging from marine near the Florida panhandle to urban and industrial in the Houston-Galveston area. These varied sources provided an opportunity to investigate the role of aerosol sources and chemistry in the potential activation of particles to form cloud droplets. Measurements were made of CCN concentrations, aerosol chemical composition in the size range relevant for particle activation in warm clouds, and aerosol size distributions. Variability in aerosol composition was parameterized by the mass fraction of Hydrocarbon-like Organic Aerosol (HOA) for particle diameters less than 200 nm (vacuum aerodynamic). The HOA mass fraction in this size range was lowest for marine aerosol and highest for aerosol sampled close to anthropogenic sources. Combining all data from the experiment reveals that composition (defined by HOA mass fraction) explains 40% of the variance in the critical diameter for particle activation at the instrumental supersaturation (S) of 0.44%. Correlations between HOA mass fraction and aerosol mean diameter show that these two parameters are essentially independent of one another for this data set. We conclude that, based on the variability of the HOA mass fraction observed during TexAQS-GoMACCS, variability in particle composition played a significant role in determining the fraction of particles that could activate to form cloud droplets. Using a simple model based on Köhler theory and the assumption that HOA is insoluble, we estimate the degree to which calculated CCN

  2. 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.

  3. 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.

  4. 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

  5. Particle size analysis of radioactive aerosols formed by irradiation of argon using 65 MeV quasi-monoenergetic neutrons.

    PubMed

    Endo, A; Noguchi, H; Tanaka, Su; Kanda, Y; Oki, Y; Iida, T; Sato, K; Tsuda, S

    2002-04-01

    The size distributions of 38Cl and 39Cl aerosols formed from the irradiation of argon gas containing di-octyl phthalate (DOP) aerosols by 65 MeV quasi-monoenergetic neutrons were measured to study the formation mechanism of radioactive aerosols in high-energy radiation fields. Both the number size distribution and the activity-weighted size distribution were measured using an electrical low-pressure impactor. It was found that the 35Cl and 39Cl aerosols are formed by attachment of the radioactive atoms generated by the neutron-induced reaction to the DOP aerosol particles.

  6. Polar organic marker compounds in atmospheric aerosols: Determination, time series, size distributions and sources

    NASA Astrophysics Data System (ADS)

    Kourtchev, Ivan

    Terrestrial vegetation releases substantial amounts of reactive volatile organic compounds (VOCs; e.g., isoprene, monoterpenes) into the atmosphere. The VOCs can be rapidly photooxidized under conditions of high solar radiation, yielding products that can participate in new particle formation and growth processes above forests. This thesis focuses on the characterization, identification and quantification of oxidation products of biogenic VOC (BVOCs) as well as other species (tracer compounds) that provide information on aerosol sources and source processes. Atmospheric aerosols from various forested sites (i.e., Hyytiala, southern Finland; Rondonia, Brazil; K-Puszta, Hungary and Julich, Germany) were analyzed with Gas Chromotography/Mass Spectrometry (GC/MS) using analytical procedure that targets polar organic compounds. The study demonstrated that isoprene (i.e., 2-methyerythritol, 2-methylthreitol, 2-methylglyceric acid and C5-alkene triols (2-methyl-1,3,4-trihydroxy-l-butene (cis and trans) and 3 methyl-2,3,4-trihydroxy-1-butene)) and monoterpene (pinic acid, norpinic acid, 3-hydroxyglutaric acid and 3-methyl-1,2,3-butanetricarboxylic acid) oxidation products were present in substantial concentrations in atmospheric aerosols suggesting that oxidation of BVOC from the vegetation is an important process in all studied sites. On the other hand, presence of levoglucosan, biomass burning marker, especially in Amazonian rain forest site at Rondonia, Brazil, pointed that all sites were affected by anthropogenic activities, namely biomass burning. Other identified compounds included plyols, arabitol, mannitol and erythritol, which are marker compounds for fungal spores and monosacharides, glucose and fructose, markers for plant polens. Temporal variations as well as mass size distributions of the detected species confirmed the possible formation mechanisms of marker compounds.

  7. If I know the aerosol compositional model identifier, how can I get information about the corresponding aerosol model?

    Atmospheric Science Data Center

    2014-12-08

    ... (APOP) and the Mixture files. The Mixture file lists the pure particles in each model identifier. The APOP then gives the detailed information for the pure particles. More information on the MISR aerosol model is available from ...

  8. Number Size distribution of Atmospheric Submicron Aerosols in Thirteen Sites across China

    NASA Astrophysics Data System (ADS)

    Peng, Jianfei; Hu, Min; Wang, Zhibin; Yue, Dingli

    2013-04-01

    Number concentration and size distribution (15-600nm) of atmospheric submicron aerosols have been measured in thirteen sites across China during several campaigns from 2006 to 2011. All the sampling sites are categorized into four types, including five urban sites, four suburban sites, three regional sites and two cruise measurements along the eastern coast of China. Spatial and temporal variation of aerosols in nucleation mode (with particle diameter between 15 and 25 nm), Aitken mode (with particle diameter between 25 and 90 nm) as well as accumulation mode (with particle diameter between 90 and 600 nm) in all sites are investigated. Particle number concentration in urban and suburban sites are 2-5 times higher than in regional and sites and cruise measurements. Higher concentration of nucleation mode particles as well as more new particle formation events are found in urban and suburban sites than in regional sites and cruise measurements, indicating high formation rates in the urban sites due to anthropogenic emission of new particles formation precursors. Aitken mode particles are abundant in both urban sites and suburban sites, with larger variation in urban sites than in suburban sites. Accumulation mode particles present higher concentration in winter than in summer. Diurnal trend of both Aitken and accumulation mode shows a bimodal pattern, while the pattern of Aitken mode particles is much more obvious in urban sites but can be barely found in cruise measurements. Particle concentration in accumulation mode and Aitken mode have a week correlation, with aerosols in different sites occupying different Aitken/Accumulation region. Log-normal modal fitting treatment are also used on particle size distribution data to provide the modal pattern as well as the aging information. Particle size distribution shows bimodal or trimodal patterns in most cases in urban sites. However, in regional sites and cruise measurements, the unimodal fit can always do a good job

  9. Aerosol Size and Chemical Composition in the Canadian High Arctic

    NASA Astrophysics Data System (ADS)

    Chang, R. Y. W.; Hayes, P. L.; Leaitch, W. R.; Croft, B.; O'Neill, N. T.; Fogal, P.; Drummond, J. R.; Sloan, J. J.

    2015-12-01

    Arctic aerosol have a strong annual cycle, with winter months dominated by long range transport from lower latitudes resulting in high mass loadings. Conversely, local emissions are more prominent in the summer months because of the decreased influence of transported aerosol, allowing us to regularly observe both transported and local aerosol. This study will present observations of aerosol chemical composition and particle number size distribution collected at the Polar Environment Artic Research Laboratory and the Alert Global Atmospheric Watch Observatory at Eureka (80N, 86W) and Alert (82N, 62W), Nunavut, respectively. Summer time observations of the number size distribution reveal a persistent mode of particles centered between 30-50 nm, with occasional bursts of smaller particles. The non-refractory aerosol chemical composition, measured by the Canadian Network for the Detection of Atmospheric Change quadrupole aerosol mass spectrometer, is primarily organic, with contributions from both aged and fresher organic aerosol. Factor analysis will be conducted to better understand these sources. The site at Eureka is more susceptible to long range transport since it is at the top of a mountain ridge (610 m above sea level) and will be compared to the site at Alert on an elevated plain (200 m above sea level). This will allow us to determine the relative contributions from processes and sources at the sites at different elevations. Comparisons with aerosol optical depth and GEOS-Chem model output will also be presented to put these surface measurements into context with the overlying and regional atmosphere. Results from this study contribute to our knowledge of aerosol in the high Arctic.

  10. 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}.

  11. 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.

  12. Size distribution and speciation of chromium in paint spray aerosol at an aerospace facility.

    PubMed

    Sabty-Daily, Rania A; Harris, Patricia A; Hinds, William C; Froines, John R

    2005-01-01

    Spray painters are potentially exposed to aerosol containing Cr(VI) via inhalation of chromate-based paint spray. Two field studies were conducted at an aerospace facility to determine the size distribution and speciation of Cr(VI) in paint spray aerosol. Sampled paint products consisted of sparingly soluble strontium chromate in an epoxy resin matrix, a matrix generally known for its durability and toughness. Personal aerosol samples were collected using Sierra Marple personal cascade impactors and analyzed for Cr(VI) and total Cr. The size distribution of total Cr particles in the paint aerosol had a Mass Median Aerodynamic Diameter (MMAD) of 7.5 mum [Geometric Standard Deviation (GSD = 2.7 mum)] in both field studies. The MMAD of Cr(VI) particles was 8.5 mum (GSD = 2.2 mum). Particles >2 mum constituted 90% or more of the total Cr and the Cr(VI) mass, in all sampled paint aerosols and were lognormally distributed. The target site for respiratory deposition of Cr in the aerosol was estimated based on the mass distribution of Cr according to particle size. On an average, 62% of the Cr and Cr(VI) mass in the paint aerosol consisted of particles >10 mum. This study showed that 71.8% of Cr(VI) mass in paint spray aerosol potentially inhaled by a spray painter may deposit in the head airways region. Only 2.0 and 1.4% of Cr(VI) mass in the paint aerosol may potentially deposit in the alveolar and tracheobronchial region, respectively. The ratio of Cr(VI) mass to total Cr mass was determined in bulk paint and the data indicate that Cr was predominantly in the Cr(VI) valence state, before spraying. The ratio of Cr(VI) mass to total Cr mass was also determined in paint aerosol samples. The data indicated that there was a reduction of Cr(VI) regardless of Cr aerosol particle size. Cr(VI) reduction occurred most likely during the 8 h sample collection time period. These findings are in agreement with the findings that observed Cr(VI) reduction during collection of airborne

  13. Aerosol Size Distribution in a City Influenced by Both Rural and Urban Regions

    NASA Astrophysics Data System (ADS)

    Fitzgerald, R. M.; Polanco, J.; Lozano, A.

    2006-12-01

    Most atmospheric studies have focused on sites located in either rural or urban areas. However, there are regions affected by air from both, such as the city of El Paso. Adjacent to the neighboring city of Juarez, Mexico, and in close proximity to rural areas, it is affected by desert particles and both biogenic, anthropogenic emissions. Aerosol properties largely depend upon particle size and this makes it the most important parameter for characterizing the aerosol. We focus on studies using inverse reconstruction models for particle size distribution using aerosol optical depth data. Our methodology uses Twomey's regularization technique that suppresses ill-posedness by imposing smoothing and non-negativity constraints on the desired size distributions. We have also applied T-matrix codes to study the scattering from irregularly shaped particles that exhibit rotational symmetry. Furthermore, our studies include analysis of aerosol size distributions using optic probes and soot photometers, sampled from aircraft at different heights. This work will lead to better characterization of aerosols and their impact in our rural-urban interface region. In addition, it will provide a more accurate assessment of regional transport and better boundary conditions for air quality models.

  14. Observations of Saharan Aerosols: Results of ECLATS Field Experiment. Part I: Optical Thicknesses and Aerosol Size Distributions.

    NASA Astrophysics Data System (ADS)

    Fouquart, Y.; Bonnel, B.; Chaoui Roquai, M.; Santer, R.; Cerf, A.

    1987-01-01

    A series of ground-based and airborne observations of desert aerosols, the ECLATS experiment was carried out in December 1980 in the vicinity of Niamey (Niger). This paper deals with aerosol optical thicknesses and size distributions derived from (i) in situ measurements using singe particle optical counters (a Kratel and a Knollenberg FSSP), (ii) a ground-based cascade impactor, and (iii) ground-based measurements of the spectral variation of the sober extinction.During the experiment, aerosol optical thicknesses (at 550 nm) varied from 0.20 on very clear days to 1.5 during a so-called `dry haze' episode.Comparisons between size distributions derived from in situ measurements from ground-based cascade impactor, and from inversion of the spectral optical thicknesses, showed that the optical counters drastically underestimated the concentration of small (r<0.5 m) particles It was shown that the occurrence of a `dry haze' episode was characterized by a large increase (an order of magnitude in this particular case) of the intermediate particles (r0.5 m), whereas the concentration in very (r<0.2 m) and large (r>1 m) particles remained roughly constant.

  15. Dynamics of aerosol size during inhalation: hygroscopic growth of commercial nebulizer formulations.

    PubMed

    Haddrell, Allen E; Davies, James F; Miles, Rachael E H; Reid, Jonathan P; Dailey, Lea Ann; Murnane, Darragh

    2014-03-10

    The size of aerosol particles prior to, and during, inhalation influences the site of deposition within the lung. As such, a detailed understanding of the hygroscopic growth of an aerosol during inhalation is necessary to accurately model the deposited dose. In the first part of this study, it is demonstrated that the aerosol produced by a nebulizer, depending on the airflows rates, may experience a (predictable) wide range of relative humidity prior to inhalation and undergo dramatic changes in both size and solute concentration. A series of sensitive single aerosol analysis techniques are then used to make measurements of the relative humidity dependent thermodynamic equilibrium properties of aerosol generated from four common nebulizer formulations. Measurements are also reported of the kinetics of mass transport during the evaporation or condensation of water from the aerosol. Combined, these measurements allow accurate prediction of the temporal response of the aerosol size prior to and during inhalation. Specifically, we compare aerosol composed of pure saline (150 mM sodium chloride solution in ultrapure water) with two commercially available nebulizer products containing relatively low compound doses: Breath®, consisting of a simple salbutamol sulfate solution (5 mg/2.5 mL; 1.7 mM) in saline, and Flixotide® Nebules, consisting of a more complex stabilized fluticasone propionate suspension (0.25 mg/mL; 0.5 mM in saline. A mimic of the commercial product Tobi© (60 mg/mL tobramycin and 2.25 mg/mL NaCl, pH 5.5-6.5) is also studied, which was prepared in house. In all cases, the presence of the pharmaceutical was shown to have a profound effect on the magnitude, and in some cases the rate, of the mass flux of water to and from the aerosol as compared to saline. These findings provide physical chemical evidence supporting observations from human inhalation studies, and suggest that using the growth dynamics of a pure saline aerosol in a lung inhalation model

  16. 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

  17. 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

  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. Particle size distribution of ambient aerosols in an industrial area.

    PubMed

    Rao, B Padma; Srivastava, A; Yasmin, F; Ray, S; Gupta, N; Chauhan, C; Rao, C V C; Wate, S R

    2012-05-01

    Aerosol samples of PM(10) and PM(2.5) were collected from 38 sampling locations in and around the industrial area. The 24 h average mass concentration of PM(10) and PM(2.5) was 137.5 and 61.5 μg/m(3) respectively during summer, 122 and 97.5 μg/m(3) respectively in winter and 70 and 54 μg/m(3) respectively during post monsoon season. The relative contribution of coarse, fine and ultrafine particle to ambient air was analyzed for its temporal and seasonal variability in an industrialized area. This paper aims to establish baseline between PM(10) and PM(2.5) mass concentration levels.

  20. Retrieval of aerosol microphysical properties from AERONET photopolarimetric measurements: 1. Information content analysis

    NASA Astrophysics Data System (ADS)

    Xu, Xiaoguang; Wang, Jun

    2015-07-01

    This paper is the first part of a two-part study that aims to retrieve aerosol particle size distribution (PSD) and refractive index from the multispectral and multiangular polarimetric measurements taken by the new-generation Sun photometer as part of the Aerosol Robotic Network (AERONET). It provides theoretical analysis and guidance to the companion study in which we have developed an inversion algorithm for retrieving 22 aerosol microphysical parameters associated with a bimodal PSD function from real AERONET measurements. Our theoretical analysis starts with generating the synthetic measurements at four spectral bands (440, 675, 870, and 1020 nm) with a Unified Linearized Vector Radiative Transfer Model for various types of spherical aerosol particles. Subsequently, the quantitative information content for retrieving aerosol parameters is investigated in four observation scenarios, i.e., I1, I2, P1, and P2. Measurements in the scenario (I1) comprise the solar direct radiances and almucantar radiances that are used in the current AERONET operational inversion algorithm. The other three scenarios include different additional measurements: (I2) the solar principal plane radiances, (P1) the solar principal plane radiances and polarization, and (P2) the solar almucantar polarization. Results indicate that adding polarization measurements can increase the degree of freedom for signal by 2-5 in the scenario P1, while not as much of an increase is found in the scenarios I2 and P2. Correspondingly, smallest retrieval errors are found in the scenario P1: 2.3% (2.9%) for the fine-mode (coarse-mode) aerosol volume concentration, 1.3% (3.5%) for the effective radius, 7.2% (12%) for the effective variance, 0.005 (0.035) for the real-part refractive index, and 0.019 (0.068) for the single-scattering albedo. These errors represent a reduction from their counterparts in scenario I1 of 79% (57%), 76% (49%), 69% (52%), 66% (46%), and 49% (20%), respectively. We further

  1. 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.

  2. 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.

  3. Processes Controlling the Seasonal Cycle of Arctic Aerosol Number and Size Distributions

    NASA Astrophysics Data System (ADS)

    Wentworth, G.; Croft, B.; Martin, R.; Leaitch, W. R.; Tunved, P.; Breider, T. J.; D'Andrea, S.; Pierce, J. R.; Murphy, J. G.; Kodros, J.; Abbatt, J.

    2015-12-01

    Measurements at high-Arctic sites show a strong seasonal cycle in aerosol number and size. The number of aerosols with diameters larger than 20 nm exhibits a maximum in late spring associated with a dominant accumulation mode, and a second maximum in the summer associated with a dominant Aitken mode. Seasonal-mean aerosol effective diameter ranges from about 160 nm in summer to 250 nm in winter. This study interprets these seasonal cycles with the GEOS-Chem-TOMAS global aerosol microphysics model. We find improved agreement with in situ measurements (SMPS) of aerosol size at both Alert, Nunavut, and Mt. Zeppelin, Svalbard following model developments: 1) increase the efficiency of wet scavenging in the Arctic summer and 2) represent coagulation between interstitial aerosols and aerosols activated to form cloud droplets. Our simulations indicate that the dominant summer-time Aitken mode is associated with increased efficiency of wet removal, which limits the number of larger aerosols and promotes local new-aerosol formation. We also find an important role of interstitial coagulation in clouds in the Arctic, which limits the number of Aitken-mode aerosols in the non-summer seasons when direct wet removal of these aerosols is inefficient. The summertime Arctic atmosphere is particularly pristine and strongly influenced by natural regional emissions which have poorly understood climate impacts. Especially influenced are the climatic roles of atmospheric particles and clouds. Here we present evidence that ammonia (NH3) emissions from migratory-seabird guano (dung) are the primary contributor to summertime free ammonia levels recently measured in the Canadian Arctic atmosphere. These findings suggest that ammonia from seabird guano is a key factor contributing to bursts of new-particle formation, which are observed every summer in the near-surface atmosphere at Alert, Canada. Chemical transport model simulations show that these newly formed particles can grow by vapour

  4. Aerosol mobility imaging for rapid size distribution measurements

    SciTech Connect

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

    PubMed

    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.

  6. 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

  7. SEM-EDX analysis of various sizes aerosols in Delhi India.

    PubMed

    Srivastava, Arun; Jain, V K; Srivastava, Anchal

    2009-03-01

    Scanning electron microscopy-energy dispersive X-ray analysis (SEM-EDX) was used to understand the differences in morphology, elemental composition and particle density of aerosols in different five size ranges to further investigate the potential sources as well as transport of pollutants from/at a much polluted and a very clean area of Delhi. Aerosol samples were obtained in five different size ranges viz. > or = 10.9, 10.9-5.4, 5.4-1.6, 1.6-0.7 and < or = 0.7 microm from a considerably very clean and a much polluted area of Delhi. It was observed that at polluted area most of the particles irrespective of size are of anthropogenic origin. At clean area, in coarse size fractions particles are of natural origin while in fine size range the presence of anthropogenic particles suggests the transport of particles from one area to the other.

  8. Spatially resolved measurements of size and velocity distributions of aerosol droplets from a direct injection nebulizer

    SciTech Connect

    Shum, S.C.K.; Johnson, S.K.; Pang, H.M.; Houk, R.S. )

    1993-05-01

    Aerosol droplet sizes and velocities from a direct injection nebulizer (DIN) are measured with radial and axial spatial resolution by phase Doppler particle analysis (PDPA). The droplets on the central axis of the spray become finer and their size becomes more uniform when [approx]20% methanol is added to the usual aqueous solvent. This could explain why the analyte signal is a maximum at this solvent composition when the DIN is used for inductively coupled plasma-mass spectrometry (ICP-MS). Mean droplet velocities are 12 to 22 m s[sup [minus]1] with standard deviations of [plus minus]4 to [plus minus]7 m s[sup [minus]1]. The outer fringes of the aerosol plume tend to be enriched in large droplets. The Sauter mean diameter (D[sub 3,2]) and velocity of the droplets also vary substantially with axial position in the aerosol plume. 35 refs., 10 figs., 1 tab.

  9. Atmospheric correction of ocean color imagery: use of the junge power-law aerosol size distribution with variable refractive index to handle aerosol absorption.

    PubMed

    Chomko, R M; Gordon, H R

    1998-08-20

    When strongly absorbing aerosols are present in the atmosphere, the usual two-step procedure of processing ocean color data-(1) atmospheric correction to provide the water-leaving reflectance (rho(w)), followed by (2) relating rho(w) to the water constituents-fails and simultaneous estimation of the ocean and aerosol optical properties is necessary. We explore the efficacy of using a simple model of the aerosol-a Junge power-law size distribution consisting of homogeneous spheres with arbitrary refractive index-in a nonlinear optimization procedure for estimating the relevant oceanic and atmospheric parameters for case 1 waters. Using simulated test data generated from more realistic aerosol size distributions (sums of log-normally distributed components with different compositions), we show that the ocean's pigment concentration (C) can be retrieved with good accuracy in the presence of weakly or strongly absorbing aerosols. However, because of significant differences in the scattering phase functions for the test and power-law distributions, large error is possible in the estimate of the aerosol optical thickness. The positive result for C suggests that the detailed shape of the aerosol-scattering phase function is not relevant to the atmospheric correction of ocean color sensors. The relevant parameters are the aerosol single-scattering albedo and the spectral variation of the aerosol optical depth. We argue that the assumption of aerosol sphericity should not restrict the validity of the algorithm and suggest an avenue for including colored aerosols, e.g., wind-blown dust, in the procedure. A significant advantage of the new approach is that realistic multicomponent aerosol models are not required for the retrieval of C.

  10. Aerosols

    Atmospheric Science Data Center

    2013-04-17

    ... article title:  Aerosols over Central and Eastern Europe     View Larger Image ... last weeks of March 2003, widespread aerosol pollution over Europe was detected by several satellite-borne instruments. The Multi-angle ...

  11. 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...

  12. PIXE-PIGE analysis of size-segregated aerosol samples from remote areas

    NASA Astrophysics Data System (ADS)

    Calzolai, G.; Chiari, M.; Lucarelli, F.; Nava, S.; Taccetti, F.; Becagli, S.; Frosini, D.; Traversi, R.; Udisti, R.

    2014-01-01

    The chemical characterization of size-segregated samples is helpful to study the aerosol effects on both human health and environment. The sampling with multi-stage cascade impactors (e.g., Small Deposit area Impactor, SDI) produces inhomogeneous samples, with a multi-spot geometry and a non-negligible particle stratification.

  13. 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...

  14. In Situ Aerosol-Size Distributions and Clear-Column Radiative Closure During ACE-2

    NASA Technical Reports Server (NTRS)

    Collins, R.; Jonsson, H. H.; Seinfeld, J. H.; Flagan, R. C.; Gasso, S.; Hegg, D. A.; Russell, P. B.; Schmid, B.; Livingston, J. M.; Oestroem, E.

    1999-01-01

    As part of the second Aerosol Characterization Experiment (ACE-2) during June and July of 1997, aerosol-size distributions were measured on board the CIRPAS Pelican aircraft through the use of a Differential Mobility Analyzer (DMA) and 2 Optical Particle Counters (OPCs). During the campaign, the boundary-layer aerosol typically possessed characteristics representative of a background marine aerosol or a continentally influenced aerosol, while the free-tropospheric aerosol was characterized by the presence or absence of a Saharan dust layer. A range of radiative closure comparisons were made using the data obtained during vertical profiles flown on 4 missions. Of particular interest here are the comparisons made between the optical properties as determined through the use of measured aerosol-size distributions and those measured directly by an airborne 14-wavelength sunphotometer and 3 nephelometers. Variations in the relative humidity associated with each of the direct measurements required consideration of the hygroscopic properties of the aerosol for size-distribution-based calculations. Simultaneous comparison with such a wide range of directly-measured optical parameters not only offers evidence of the validity of the physicochemical description of the aerosol when closure is achieved, but also provides insight into potential sources of error when some or all of the comparisons result in disagreement. Agreement between the derived and directly-measured optical properties varied for different measurements and for different cases. Averaged over the 4 case studies, the derived extinction coefficient at 525 nm exceeded that measured by the sunphotometer by 2.5% in the clean boundary layer, but underestimated measurements by 13% during pollution events. For measurements within the free troposphere, the mean derived extinction coefficient was 3.3% and 17% less than that measured by the sunphotometer during dusty and non-dusty conditions, respectively. Likewise

  15. In Situ Aerosol Size Distributions and Clear Column Radiative Closure During ACE-2

    NASA Technical Reports Server (NTRS)

    Collins, D. R.; Johnson, H. H.; Seinfeld, J. H.; Flagan, R. C.; Gasso, S.; Hegg, D. A.; Russell, P. B.; Schmid, B.; Livingston, J. M.; Oestroem, E.; Noone, K. J.; Russell, L. M.; Putaud, J. P.

    2000-01-01

    As part of the second Aerosol Characterization Experiment (ACE-2) during June and July of 1997, aerosol size distributions were measured on board the CIRPAS Pelican aircraft through the use of a DMA and two OPCS. During the campaign, the boundary layer aerosol typically possessed characteristics representative of a background marine aerosol or a continentally influenced aerosol, while the free tropospheric aerosol was characterized by the presence or absence of a Saharan dust layer. A range of radiative closure comparisons were made using the data obtained during vertical profiles flown on four missions. Of particular interest here are the comparisons made between the optical properties as determined through the use of measured aerosol size distributions and those measured directly by an airborne 14-wavelength sunphotometer and three nephelometers. Variations in the relative humidity associated with each of the direct measurements required consideration of the hygroscopic properties of the aerosol for size distribution based calculations. Simultaneous comparison with such a wide range of directly measured optical parameters not only offers evidence of the validity of the physicochemical description of the aerosol when closure is achieved, but also provides insight into potential sources of error when some or all of the comparisons result in disagreement. Agreement between the derived and directly measured optical properties varied for different measurements and for different cases. Averaged over the four case studies, the derived extinction coefficient at 525 nm exceeded that measured by the sunphotomoter by 2.5% in the clean boundary later, but underestimated measurements by 13% during pollution events. For measurements within the free troposphere, the mean derived extinction coefficient was 3.3% and 17% less than that measured by the sunphotometer during dusty and nondusty conditions, respectively. Likewise, averaged discrepancies between the derived and measured

  16. 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.

  17. Size-dependent chemical ageing of oleic acid aerosol under dry and humidified conditions

    NASA Astrophysics Data System (ADS)

    Al-Kindi, Suad S.; Pope, Francis D.; Beddows, David C.; Bloss, William J.; Harrison, Roy M.

    2016-12-01

    A chemical reaction chamber system has been developed for the processing of oleic acid aerosol particles with ozone under two relative humidity conditions: dry and humidified to 65 %. The apparatus consists of an aerosol flow tube, in which the ozonolysis occurs, coupled to a scanning mobility particle sizer (SMPS) and an aerosol time-of-flight mass spectrometer (ATOFMS) which measure the evolving particle size and composition. Under both relative humidity conditions, ozonolysis results in a significant decrease in particle size and mass which is consistent with the formation of volatile products that partition from the particle to the gas phase. Mass spectra derived from the ATOFMS reveal the presence of the typically observed reaction products: azelaic acid, nonanal, oxononanoic acid and nonanoic acid, as well as a range of higher molecular weight products deriving from the reactions of reaction intermediates with oleic acid and its oxidation products. These include octanoic acid and 9- and 10-oxooctadecanoic acid, as well as products of considerably higher molecular weight. Quantitative evaluation of product yields with the ATOFMS shows a marked dependence upon both particle size association (from 0.3 to 2.1 µm diameter) and relative humidity. Under both relative humidity conditions, the percentage residual of oleic acid increases with increasing particle size and the main lower molecular weight products are nonanal and oxononanoic acid. Under dry conditions, the percentage of higher molecular weight products increases with increasing particle size due to the poorer internal mixing of the larger particles. Under humidified conditions, the percentage of unreacted oleic acid is greater, except in the smallest particle fraction, with little formation of high molecular weight products relative to the dry particles. It is postulated that water reacts with reactive intermediates, competing with the processes which produce high molecular weight products. Whilst the

  18. Atmospheric Observations of Aerosol Sizes, Sulfuric Acid and Ammonia Measured in Kent, Ohio

    NASA Astrophysics Data System (ADS)

    Pavuluri, C.; Benson, D. R.; Dailey, B.; Lee, S.

    2008-12-01

    Atmospheric particles affect atmospheric composition, cloud formation, global radiation budget, and human health. Nucleation is a gas-to-particle conversion process in which new particles form directly from gas phase species and is a key process that controls particle number concentrations. The most common feature of the new particle formation events is a substantial increase of number concentrations of nucleation mode particles reaching up to 105-106 cm-3 in the condensable vapor-laden air. There are several nucleation mechanisms for tropopsheric aerosol formation, but it is unclear which nucleation process dominates. In particular, observations and modeling studies show that ammonia can be important for atmospheric nucleation in the boundary layer, but simultaneous measurements of aerosol sizes and precursors including sulfuric acid and ammonia are critically lacking. In order to overcome these shortcomings, we conduct atmospheric observations of new particle formation in Kent, OH. We have measured aerosol sizes and concentrations for particles in the size range from 3-102 nm semi- continuously from December 2005 and for particles from 3-1000 nm continuously from September 2007 in Kent State campus, Kent, OH (with an inlet placed at ~11.5 m above ground level). We also simultaneously measure sulfuric acid and ammonia, two most important inorganic aerosol precursors, with two chemical ionization mass spectrometers (CIMS) from August 2008. Kent, located in Northeastern Ohio, is relatively rural itself, but is also surrounded by several urban cities within 40 miles. Because of the combination of its relatively rural environment (hence low surface areas of aerosol particles), active vegetation (organic and NH3 emissions), and possible transport of aerosol precursors from the surrounding urban and industrialized areas, Kent is a unique location to make new particle formation studies. So far, most of new particle formation observations made typically in US were at

  19. Dust size parameterization in RegCM4: Impact on aerosol burden and radiative forcing

    NASA Astrophysics Data System (ADS)

    Tsikerdekis, A.; Zanis, P.; Steiner, A. L.; Solmon, F.; Amiridis, V.; Marinou, E.; Katragkou, E.; Karacostas, T.; Foret, G.

    2015-12-01

    We investigate the sensitivity of two dust parameterizations of the regional climate model RegCM4, for the period 2008-2012, over a large domain focused on the Sahara and the Mediterranean. We implement two size bin distributions: 1) a 4-bin approach, where each bin is delimited using an isolog approach and every size group has equal ranges in logarithmic scale according to the diameter of the dust particles, and 2) a 12-bin approach with each bin defined according to an isogradient method, where the size ranges are dependent on the dry deposition velocity of dust particles. Increasing the number of the transported dust size bin improves the representation of the physical properties of dust particles that belong on the same group. Thus, more size bins minimize the error and improve the simulation of atmospheric processes. The emission, deposition and transport of dust are evaluated combined for each experiment to determine the impact of dust size bin partition. The radiative effects of dust over the area are also discussed and evaluated with the CALIPSO Aerosol Optical Depth (AOD) pure dust product. Techniques for the discrimination of the dust component from other aerosol types have been recently developed in the framework of the LIVAS (LIdar climatology of Vertical Aerosol Structure for space-based lidar simulation studies- http://lidar.space.noa.gr:8080/livas/).

  20. Designing of Copper Nanoparticle Size Formed via Aerosol Pyrolysis

    NASA Astrophysics Data System (ADS)

    Jokanović, Vukoman; Čolović, Božana; Stopić, Srećko; Friedrich, Bernd

    2012-11-01

    In this article, the synthesis and structural design of spherical, nonagglomerated particles of copper powder, synthesized by ultrasonic atomization of copper sulfate solutions in hydrogen atmosphere at 1173 K (900 °C), was investigated. Well-controlled particle sizes of Cu powders were obtained from precursor solutions of various concentrations. The mean particle diameters and the ranges of particle size distribution were investigated by scanning electron microscopy (SEM). The diameter values of Cu particles obtained experimentally and estimated theoretically, using the most frequently applied atomization models, were compared. Special attention was paid to our break up capillary waves model, described elsewhere and significantly advanced by Jokanović's theoretical approach, which was applied for the first time to a copper metal system as described in this article. The best agreement between the calculated and the experimentally obtained values was found using this model.

  1. 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.

  2. State Guideline Information: Size of Site.

    ERIC Educational Resources Information Center

    Weihs, Janell, Comp.

    This document presents a table of state guidelines concerning the size of educational facility sites. For the state, the formula for school site analysis is provided, along with relevant comments and the name of related documents. The information was collected from state facility reports and manuals and verified through direct contact with…

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

    NASA Astrophysics Data System (ADS)

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

    2000-03-01

    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 s. The analyzer includes a bipolar charger (Po210), 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 s 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 T-38 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 below.

  4. 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.

  5. 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.

  6. Sizing aerosolized fractal nanoparticle aggregates through Bayesian analysis of wide-angle light scattering (WALS) data

    NASA Astrophysics Data System (ADS)

    Huber, Franz J. T.; Will, Stefan; Daun, Kyle J.

    2016-11-01

    Inferring the size distribution of aerosolized fractal aggregates from the angular distribution of elastically scattered light is a mathematically ill-posed problem. This paper presents a procedure for analyzing Wide-Angle Light Scattering (WALS) data using Bayesian inference. The outcome is probability densities for the recovered size distribution and aggregate morphology parameters. This technique is applied to both synthetic data and experimental data collected on soot-laden aerosols, using a measurement equation derived from Rayleigh-Debye-Gans fractal aggregate (RDG-FA) theory. In the case of experimental data, the recovered aggregate size distribution parameters are generally consistent with TEM-derived values, but the accuracy is impaired by the well-known limited accuracy of RDG-FA theory. Finally, we show how this bias could potentially be avoided using the approximation error technique.

  7. Relevance of aerosol size spectrum analysis as support to qualitative source apportionment studies.

    PubMed

    Manigrasso, M; Febo, A; Guglielmi, F; Ciambottini, V; Avino, P

    2012-11-01

    This work presents a diagnostic methodology in support to source apportionment studies to identify remote and local pollution sources. It is based on the temporal analysis of both PM size distributions and PM size fraction correlation along with natural radioactivity measurements as index of Planetary Boundary Layer dynamic. A correlation drop is indicative of changing aerosol sources. When this observation is coupled with decreasing level of natural radioactivity and increasing aerosol concentration, be it coarse or fine, it is indicative of the inflow of remote polluted air masses. The methodology defines in which size range operates the contribution of remote pollution sources. It was applied to two PM10 pollution episodes: the first involved the advection of coarse PM, the second entailed the inflow of two air masses, one transporting coarse dust and the other fine PM. Dust models and backward trajectories analysis confirmed such results, indicating the air mass provenience.

  8. Aerosol Size Distributions Measured in the Upper Troposphere and Lower Stratosphere: Formation, Coagulation, Transport and Sedimentation of the Background Non-Volcanic Aerosols

    NASA Astrophysics Data System (ADS)

    Lee, S.; Wilson, J. C.; Reeves, J. M.; Brock, C. A.; Jonsson, H. H.; Lowenstein, M.; Mahoney, M. J.; Herman, R. L.; Anderson, J. G.; Xueref, I.; Gerbig, C.; Andrews, A. E.; Hinsta, E.

    2002-12-01

    This study presents the particle size distribution of non-volcanic aerosols in the lower stratosphere and upper troposphere measured from 1995 to 2000 during five different high-altitude aircraft missions (STRAT, POLARIS, WAM, ACCENT, and SOLVE). The Focused Cavity Aerosol Spectrometer (FCAS), Condensation Nucleus Counter (CNC), and Nucleation-Mode Aerosol Sizing Spectrometer (N-MASS) were used to characterize the particle sizes in the diameter range from 4 to 2000 nm. Measurements were made at latitudes from 3.4S to 90N and the pressure altitudes form 7 to 21 km. These particle size distributions were analyzed using the potential temperature, tropopause height, and the mixing ratio of gas phase tracers such as N2O, CO2, NOy, O3 and water vapor. Particle formation, growth and sedimentation were studied to examine how the aerosol dynamics and atmospheric transport (Holton et al., 1995) determine the steady state aerosol size distribution in the lower stratosphere. This comprehensive data set will help us to better understand the origins and fate of the stratospheric background aerosols. Reference: Holton, J. R., et al., Stratosphere-troposphere exchange, Rev. Geophys., 33, 403-439, 1995.

  9. 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

  10. 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.

  11. Size-resolved trace metal characterization of aerosols emitted by four important source types in Switzerland

    NASA Astrophysics Data System (ADS)

    Buerki, Peter R.; Gaelli, Brigitte C.; Nyffeler, Urs P.

    In central Switzerland five types of emission sources are mainly responsible for airborne trace metals: traffic, industrial plants burning heavy oil, resuspension of soil particles, residential heatings and refuse incineration plants. The particulate emissions of each of these source types except refuse incineration were sampled using Berner impactors and the mass and elemental size distributions of Cd, Cu, Mn, Pb, Zn, As and Na determined. Cd, Na and Zn are not characteristic for any of these source types. As and Cu, occurring in the fine particle fractions are characteristic for heavy oil combustion, Mn for soil dust and sometimes for heavy and fuel oil combustion and Pb for traffic aerosols. The mass size distributions of aerosols originating from erosion and abrasion processes show a maximum mass fraction in the coarse particle range larger than about 1 μm aerodynamic equivalent diameters (A.E.D.). Aerosols originating from combustion processes show a second maximum mass fraction in the fine particle range below about 0.5μm A.E.D. Scanning electron microscopy combined with an EDS analyzer was used for the morphological characterization of emission and ambient aerosols.

  12. Ship measurements of submicron aerosol size distributions over the Yellow Sea and the East China Sea

    NASA Astrophysics Data System (ADS)

    Kim, Jong Hwan; Yum, Seong Soo; Lee, Young-Gon; Choi, Byoung-Cheol

    2009-08-01

    During the spring of 2005, the total particle concentrations and the submicron aerosol size distributions were measured on board the research vessel over the south sea of Korea and the Korean sector of the Yellow Sea. Similar measurements were made over the East China Sea in autumn 2005. The aerosol properties varied dynamically according to the meteorological conditions, the proximity to the land masses and the air mass back trajectories. The average total particle concentration was the lowest over the East China Sea, 4335 ± 2736 cm - 3, but the instantaneous minimum, 837 cm - 3, for the entire ship measurement was recorded during the Yellow Sea cruise. There was also a long (more than 6 h) stretch of low total particle concentrations that fell as low as 1025 cm - 3 during the East China Sea cruise when the ship was the farthest from the shores and the air mass back trajectories resided long hours over the sea. These observations lead to the suggestion of ~ 1000 cm - 3 as the background total particle concentration over the marine boundary layer in the studied region of the Yellow Sea and the East China Sea, implying significant anthropogenic influence even for the background value. In the mean time, average aerosol size distributions were unimodal and the mode diameter ranged between 52 and 86 nm, excluding the fog periods, which suggests that the aerosols measured in this study experienced relatively less aging processes within the marine boundary layer.

  13. Size-Resolved Chemical Analysis of Individual Atmospheric Aerosols near Barrow, Alaska

    NASA Astrophysics Data System (ADS)

    Gunsch, M.; Barrett, T. E.; Sheesley, R. J.; Pratt, K.

    2015-12-01

    Climate change is having noticeable impacts on the Arctic with increasing temperatures and decreasing sea ice coverage. Loss of sea ice is leading to development of oil and gas extraction activities and increased shipping in the Arctic. Arctic aerosol emissions are expected to increase with increasing anthropogenic activities and production of sea spray aerosol. These particles have significant climate effects, including interacting with radiation, forming cloud droplets and ice crystals, and depositing onto surfaces. Given the complexity and evolving nature of atmospheric particles, as well as the challenges associated with Arctic measurements, significant uncertainties remain in our understanding of particle sources, evolution, and impacts in the Arctic. To investigate the size and chemistry of individual particles in real-time, an aerosol time-of-flight mass spectrometer (ATOFMS) was deployed to Barrow, Alaska during August-September 2015. Parallel size-resolved number concentration measurements allow the quantification of number and mass concentrations of particles from various sources, including sea spray aerosol, biomass burning, and diesel combustion, for example.

  14. Aerosol indirect effect from turbulence-induced broadening of cloud-droplet size distributions

    NASA Astrophysics Data System (ADS)

    Kant Chandrakar, Kamal; Cantrell, Will; Chang, Kelken; Ciochetto, David; Niedermeier, Dennis; Ovchinnikov, Mikhail; Shaw, Raymond A.; Yang, Fan

    2016-12-01

    The influence of aerosol concentration on the cloud-droplet size distribution is investigated in a laboratory chamber that enables turbulent cloud formation through moist convection. The experiments allow steady-state microphysics to be achieved, with aerosol input balanced by cloud-droplet growth and fallout. As aerosol concentration is increased, the cloud-droplet mean diameter decreases, as expected, but the width of the size distribution also decreases sharply. The aerosol input allows for cloud generation in the limiting regimes of fast microphysics (τc<τtτc<τt) for high aerosol concentration, and slow microphysics (τc>τtτc>τt) for low aerosol concentration; here, τcτc is the phase-relaxation time and τtτt is the turbulence-correlation time. The increase in the width of the droplet size distribution for the low aerosol limit is consistent with larger variability of supersaturation due to the slow microphysical response. A stochastic differential equation for supersaturation predicts that the standard deviation of the squared droplet radius should increase linearly with a system time scale defined as τs1=τc1+τt

  15. The weather dependence of particle size distribution of indoor radioactive aerosol associated with radon decay products.

    PubMed

    Mostafa, A M A; Tamaki, K; Moriizumi, J; Yamazawa, H; Iida, T

    2011-07-01

    This study was performed to measure the activity size distribution of aerosol particles associated with short-lived radon decay products in indoor air at Nagoya University, Nagoya, Japan. The measurements were performed using a low pressure Andersen cascade impactor under variable meteorological conditions. The results showed that the greatest activity fraction was associated with aerosol particles in the accumulation size range (100-1000 nm) with a small fraction of nucleation mode (10-100 nm). Regarding the influence of the weather conditions, the decrease in the number of accumulation particles was observed clearly after rainfall without significant change in nucleation particles, which may be due to a washout process for the large particles.

  16. 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

  17. Detailed mass size distributions of atmospheric aerosol species in the Negev desert, Israel, during ARACHNE-96

    NASA Astrophysics Data System (ADS)

    Maenhaut, Willy; Ptasinski, Jacek; Cafmeyer, Jan

    1999-04-01

    As part of the 1996 summer intensive of the Aerosol, RAdiation and CHemistry Experiment (ARACHNE-96), the mass size distribution of various airborne particulate elements was studied at a remote site in the Negev Desert, Israel. Aerosol collections were made with 8-stage PIXE International cascade impactors (PCIs) and 12-stage small deposit area low pressure impactors (SDIs) and the samples were analyzed by PIXE for about 20 elements. The mineral elements (Al, Si, Ca, Ti, Fe) exhibited a unimodal size distribution which peaked at about 6 μm, but the contribution of particles larger than 10 μm was clearly more pronounced during the day than during night. Sulphur and Br had a tendency to exhibit two modes in the submicrometer size range, with diameters at about 0.3 and 0.6 μm, respectively. The elements V and Ni, which are indicators of residual fuel burning, showed essentially one fine mode (at 0.3 μm) in addition to a coarse mode which represented the mineral dust contribution. Overall, good agreement was observed between the mass size distributions from the PCI and SDI devices. The PCI was superior to the SDI for studying the size distribution in the coarse size range, but the SDI was clearly superior for unravelling the various modes in the submicrometer size range.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. Measurement of Sulfur Isotope Ratios in Micrometer-Sized Aerosol Samples by NanoSIMS

    NASA Astrophysics Data System (ADS)

    Winterholler, B.; Hoppe, P.; Foley, S.; Andreae, M. O.

    2005-12-01

    The isotopic composition of sulfur in the atmosphere is highly variable and source dependent. Sulfur isotopic ratios are a well established tool for identifying sources of sulfur in the environment, estimating emission factors, and tracing the spread of sulfur from anthropogenic point sources in terrestrial ecosystems. Conventional mass spectrometry needs a minimum of 1 micromol of sulfur to perform one analysis. In the case of atmospheric aerosol particles the results of such an analysis averages the isotopic compositions of millions of aerosol particles, and thus normally includes several different types of sulfur aerosol. The new Cameca NanoSIMS 50 ion microprobe technique permits analysis of individual aerosol particles with volumes down to 0.3 cubic micron and a precision for delta34S of 3-10 (2 sigma). As a result, this technique is able to introduce a new scale into the study of the atmospheric sulfur cycle. Linking the chemical, mineralogical, morphological and isotopic information of individual particles will allow a better understanding of external and internal mixing states by analyzing more than one spot on coarse mode particles. Moreover it will improve source identification by complementing the chemical and isotopic information. First samples have been collected from the Sahara desert, an urban site in central Europe, and a costal site in Western Ireland and show the potentials of this new technique.

  4. 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

  5. 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

  6. 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

  7. Composition, size and cloud condensation nuclei activity of biomass burning aerosol from northern Australian savannah fires

    NASA Astrophysics Data System (ADS)

    Mallet, Marc D.; Cravigan, Luke T.; Milic, Andelija; Alroe, Joel; Ristovski, Zoran D.; Ward, Jason; Keywood, Melita; Williams, Leah R.; Selleck, Paul; Miljevic, Branka

    2017-03-01

    The vast majority of Australia's fires occur in the tropical north of the continent during the dry season. These fires are a significant source of aerosol and cloud condensation nuclei (CCN) in the region, providing a unique opportunity to investigate the biomass burning aerosol (BBA) in the absence of other sources. CCN concentrations at 0.5 % supersaturation and aerosol size and chemical properties were measured at the Australian Tropical Atmospheric Research Station (ATARS) during June 2014. CCN concentrations reached over 104 cm-3 when frequent and close fires were burning - up to 45 times higher than periods with no fires. Both the size distribution and composition of BBA appeared to significantly influence CCN concentrations. A distinct diurnal trend in the proportion of BBA activating to cloud droplets was observed, with an activation ratio of 40 ± 20 % during the night and 60 ± 20 % during the day. BBA was, on average, less hygroscopic during the night (κ = 0. 04 ± 0.03) than during the day (κ = 0.07 ± 0.05), with a maximum typically observed just before midday. Size-resolved composition of BBA showed that organics comprised a constant 90 % of the aerosol volume for aerodynamic diameters between 100 and 200 nm. While this suggests that the photochemical oxidation of organics led to an increase in the hygroscopic growth and an increase in daytime activation ratios, it does not explain the decrease in hygroscopicity after midday. Modelled CCN concentrations assuming typical continental hygroscopicities produced very large overestimations of up to 200 %. Smaller, but still significant, overpredictions up to ˜ 100 % were observed using aerosol mass spectrometer (AMS)- and hygroscopicity tandem differential mobility analyser (H-TDMA)-derived hygroscopicities as well as campaign night and day averages. The largest estimations in every case occurred during the night, when the small variations in very weakly hygroscopic species corresponded to large

  8. Size-resolved characterization of the polysaccharidic and proteinaceous components of sea spray aerosol

    NASA Astrophysics Data System (ADS)

    Aller, Josephine Y.; Radway, JoAnn C.; Kilthau, Wendy P.; Bothe, Dylan W.; Wilson, Theodore W.; Vaillancourt, Robert D.; Quinn, Patricia K.; Coffman, Derek J.; Murray, Benjamin J.; Knopf, Daniel A.

    2017-04-01

    Dissolved organic polymers released by phytoplankton and bacteria abiologically self-assemble in surface ocean waters into nano-to micro-sized gels containing polysaccharides, proteins, lipids and other components. These gels concentrate in the sea surface microlayer (SML), where they can potentially contribute to sea spray aerosol (SSA). Sea spray is a major source of atmospheric aerosol mass over much of the earth's surface, and knowledge of its properties (including the amount and nature of the organic content), size distributions and fluxes are fundamental for determining its role in atmospheric chemistry and climate. Using a cascade impactor, we collected size-fractionated aerosol particles from ambient air and from freshly generated Sea Sweep SSA in the western North Atlantic Ocean together with biological and chemical characterization of subsurface and SML waters. Spectrophotometric methods were applied to quantify the polysaccharide-containing transparent exopolymer (TEP) and protein-containing Coomassie stainable material (CSM) in these particles and waters. This study demonstrates that both TEP and CSM in surface ocean waters are aerosolized with sea spray with the greatest total TEP associated with particles <180 nm in diameter and >5 000 nm. The higher concentrations of TEP and CSM in particles >5 000 nm most likely reflects collection of microorganism cells and/or fragments. The greater concentration of CSM in larger size particles may also reflect greater stability of proteinaceous gels compared to polysaccharide-rich gels in surface waters and the SML. Both TEP and CSM were measured in the ambient marine air sample with concentrations of 2.1 ± 0.16 μg xanthan gum equivalents (XG eq.) m-3 and 14 ± 1.0 μg bovine serum albumin equivalents (BSA eq.) m-3. TEP in Sea Sweep SSA averaged 4.7 ± 3.1 μg XG eq. m-3 and CSM 8.6 ± 7.3 μg BSA eq. m-3. This work shows the transport of marine biogenic material across the air-sea interface through primary

  9. 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.

  10. 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.

  11. Role of Nucleation Mechanism on the Size Dependent Morphology of Organic Aerosol

    NASA Astrophysics Data System (ADS)

    Altaf, M. B.; Freedman, M. A.

    2015-12-01

    Cloud condensation nuclei (CCN) activation is sensitive to the size, composition, and morphology of aerosol particles < 200 nm. The properties of particles can differ on the nanoscale compared to larger sizes, as observed in atmospheric chemistry for the crystallization of particles < 40 nm in diameter. We have applied cryogenic-transmission electron microscopy (cryo-TEM) for the study of the morphology of dry, submicron organic aerosol to explore whether nanoscale effects impact the morphology of particles. Specifically, we have characterized the morphology of the poly(ethylene glycol) 400 (PEG-400)/ammonium sulfate system. We have shown that depending on the composition of the system and the mechanism of phase separation (i.e. nucleation and growth vs. spinodal decomposition), a size dependence of morphology is observed. Since phase separation by nucleation and growth should be a common occurrence in the atmosphere, we expect the majority of phase separating atmospheric particles to have a size dependent morphology, which may have important implications for CCN activation. Size dependent morphology may impact the hygroscopic properties of these particles which can affect CCN concentrations and further influence cloud formation, reflectivity, and precipitation, which will have consequences for Earth's radiation budget.

  12. 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

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

    NASA Astrophysics Data System (ADS)

    Shiraiwa, M.; Yee, L. D.; Schilling, K.; Loza, C. L.; Craven, J. S.; Zuend, A.; Ziemann, P. J.; Seinfeld, J.

    2013-12-01

    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 aerosol (SOA). 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 multi-generation 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 mid-experiment aldehyde injection confirms that heterogeneous reaction of aldehydes with organic hydroperoxides forming peroxyhemiacetals can lead to a large increase in SOA mass. The results of the current work have a number of implications for SOA models. While the dynamics of an aerosol size distribution reflects the mechanism of growth, we demonstrate here that it provides a key constraint in interpreting laboratory and ambient SOA formation. This work, although carried out specifically for the long chain alkane, dodecane, is expected to be widely applicable to other major classes of SOA precursors. SOA consists of a myriad of organic compounds containing various functional groups, which can generally undergo heterogeneous/multiphase reactions forming low-volatility products such as oligomers and other high molecular mass compounds. If particle-phase chemistry is indeed

  14. 77 FR 13329 - Information Collection; Small Business Size Representation

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-03-06

    ...; Small Business Size Representation AGENCIES: Department of Defense (DOD), General Services... of a previously approved information collection requirement regarding small business size... Information Collection 9000- 0163, Small Business Size Representation, by any of the following...

  15. Aerosol mass size distribution and black carbon over a high altitude location in Western Trans-Himalayas: Impact of a dust episode

    NASA Astrophysics Data System (ADS)

    Kompalli, Sobhan Kumar; Krishna Moorthy, K.; Suresh Babu, S.; Manoj, M. R.

    2014-12-01

    The information on the aerosol properties from remote locations provides insights into the background and natural conditions against which anthropogenic impacts could be compared. Measurements of the near surface aerosol mass size distribution from the high altitude remote site help us to understand the natural processes, such as, the association between Aeolian and fluvial processes that have a direct bearing on the mass concentrations, especially in the larger size ranges. In the present study, the total mass concentration and mass-size distribution of the near surface aerosols, measured using a 10-channel Quartz Crystal Microbalance (QCM) Impactor from a high altitude location-Hanle (32.78°N, 78.95°E, 4520 m asl) in the western Trans-Himalayas, have been used to characterize the composite aerosols. Also the impact of a highly localized, short-duration dust storm episode on the mass size distribution has been examined. In general, though the total mass concentration (Mt) remained very low (∼0.75 ± 0.61 μg m-3), interestingly, coarse mode (super-micron) aerosols contributed almost 72 ± 6% to the total aerosol mass loading near the surface. The mass-size distribution showed 3 modes, a fine particle mode (∼0.2 μm), an accumulation mode at ∼0.5 μm, and a coarse mode at ∼3 μm. During a localized short duration dust storm episode, Mt reached as high as ∼13.5 μg m-3 with coarse mode aerosols contributing to nearly 90% of it. The mass size distribution changed significantly, with a broad coarse mode so that the accumulation mode became inconspicuous. Concurrent measurements of aerosol black carbon (BC) using twin wavelength measurements of the aethalometer showed an increase in the wavelength index of absorption, from the normal values of ∼1 to 1.5 signifying the enhanced absorption at the short wavelength (380 nm) by the dust.

  16. Size-Segregated Aerosol Composition and Mass Loading of Atmospheric Particles as Part of the Pacific Northwest 2001(PNW2001) Air Quality Study In Puget Sound

    NASA Astrophysics Data System (ADS)

    Disselkamp, R. S.; Barrie, L. A.; Shutthanadan, S.; Cliff, S.; Cahill, T.

    2001-12-01

    In mid-August, 2001, an aircraft-based air-quality study was performed in the Puget Sound, WA, area entitled PNW2001 (http://www.pnl.gov/pnw2001). The objectives of this field campaign were the following: 1. reveal information about the 3-dimensional distribution of ozone, its gaseous precursors and fine particulate matter during weather conditions favoring air pollution; 2. derive information about the accuracy of urban and biogenic emissions inventories that are used to drive the air quality forecast models; and 3. examine the accuracy of modeled ozone concentration with that observed. In support of these efforts, we collected time-averaged ( { ~}10 minute averages), size-segregated, aerosol composition and mass-loading information using ex post facto analysis techniques of synchrotron x-ray fluorescence (s-XRF), proton induced x-ray emissions(PIXE), proton elastic scattering (PESA), and scanning transmission ion microscopy (STIM). This is the first time these analysis techniques have been used together on samples collected from aircraft using an optimized 3-stage rotating drum impactor. In our presentation, we will discuss the aerosol components in three aerosol size fractions as identified by statistical analysis of multielemental data (including total mass, H, Na, Mg, Al, Si, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Pb) and relate variations in these components to physical aerosol properties, other gaseous trace constituents and to air mass origin.

  17. 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

  18. Temporal variation of 7Be and 210Pb size distributions in ambient aerosol

    NASA Astrophysics Data System (ADS)

    Winkler, R.; Dietl, F.; Frank, G.; Tschiersch, J.

    The size distributions of the cosmogenic 7Be and of the long-lived radon progeny 210Pb in ambient aerosols were measured continuously from December 1994 to the end of March 1996 in ground-level air at a semi-rural location in south Germany. Aerosol sampling was performed at a height of 4 m above ground with a low-pressure cascade impactor of the Berner type covering the size range from 0.06 to 16 μm and simultaneously with an high-volume sampler. Each sampling period was 10 d. Activities of 7Be and 210Pb were measured by gamma spectrometry and aerosol mass was determined gravimetrically. In all experiments the activity distributions of 7Be as well as of 210Pb were unimodal (log-normal) and associated with submicron aerosols of about 0.5-0.6 μm aerodynamic diameter. On average, the activity median diameters of 7Be (AMD: 0.57 μm) and of 210Pb (AMD: 0.53 μm) have been found to be significantly lower than the average mass median diameter (MMD: 0.675 μm) and higher or at most equal than the respective surface median diameter (SMD: 0.465 μm) of the aerosols: SMD⩽AMD Pb210aerosols (AMD: 0.43 μm) than 7Be (AMD: 0.52 μm). Comparing the activity median diameters observed in summer with those in winter, on average significantly lower diameters were found in summer pointing to shorter residence times in the summer months.

  19. 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

  20. Development of the RAQM2 aerosol chemical transport model and predictions of the Northeast Asian aerosol mass, size, chemistry, and mixing type

    NASA Astrophysics Data System (ADS)

    Kajino, M.; Inomata, Y.; Sato, K.; Ueda, H.; Han, Z.; An, J.; Katata, G.; Deushi, M.; Maki, T.; Oshima, N.; Kurokawa, J.; Ohara, T.; Takami, A.; Hatakeyama, S.

    2012-12-01

    A new aerosol chemical transport model, the Regional Air Quality Model 2 (RAQM2), was developed to simulate the Asian air quality. We implemented a simple version of a triple-moment modal aerosol dynamics model (MADMS) and achieved a completely dynamic (non-equilibrium) solution of a gas-to-particle mass transfer over a wide range of aerosol diameters from 1 nm to super-μm. To consider a variety of atmospheric aerosol properties, a category approach was utilized in which the aerosols were distributed into four categories: particles in the Aitken mode (ATK), soot-free particles in the accumulation mode (ACM), soot aggregates (AGR), and particles in the coarse mode (COR). The aerosol size distribution in each category is characterized by a single mode. The condensation, evaporation, and Brownian coagulations for each mode were solved dynamically. A regional-scale simulation (Δx = 60 km) was performed for the entire year of 2006 covering the Northeast Asian region. The modeled PM1/bulk ratios of the chemical components were consistent with observations, indicating that the simulated aerosol mixing types were consistent with those in nature. The non-sea-salt SO42- mixed with ATK + ACM was the largest at Hedo in summer, whereas the SOSO42- was substantially mixed with AGR in the cold seasons. Ninety-eight percent of the modeled NO3- was mixed with sea salt at Hedo, whereas 53.7% of the NO3- was mixed with sea salt at Gosan, which is located upwind toward the Asian continent. The condensation of HNO3 onto sea salt particles during transport over the ocean accounts for the difference in the NO3- mixing type at the two sites. Because the aerosol mixing type alters the optical properties and cloud condensation nuclei activity, its accurate prediction and evaluation are indispensable for aerosol-cloud-radiation interaction studies.

  1. Dust and Non-dust Aerosol Outflow from Asia by Size, Time, and Composition, Spring, and Summer, 2001

    NASA Astrophysics Data System (ADS)

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

    2002-12-01

    Asian aerosols were characterized by size, time, and composition at 9 surface sites in China, Taiwan, Korea, and Japan during ACE-Asia, Spring 2001, as well as during a smaller summer NSF program. In this report, we will characterize these aerosols by source region in Asia, by aerosol mass, size distribution, time profiles, and composition, along with their forward trajectories into the Pacific. The primary aerosol collection technique was the DELTA Group slotted 8-DRUM impactor, 0.09 to 12 micrometers diameter, while compositional analysis was done every 3 hours in each size mode by synchrotron-x-ray fluorescence analysis. Comparisons of aerosols have been generated in the individual source regions, with major and trace element signatures, greatly assisting identification of aerosols seen later in transport events. Paired surface sites at low and high elevations were operational in Korea and Japan, aiding in separating truly local from regional aerosols. These data are then compared to downwind pollution events, with source regions identified by HYSPLIT isentropic trajectories. In the period between March 20 and April 20, we observed 3 major dust storms, several minor dust events, and massive non-dust aerosol emissions leaving the Asian mainland. Dust from the Takla Makan desert was observed to differ from Gobi dust by both particle size (finer) and elemental ratio (especially calcium to silicon). Very fine silicon and selenium identified coal combustion regions, while arsenic tracked mainly smelting operations. Non-sea salt sulfate contributions were generated in 8 size modes from 0.09 to 12 micrometers diameter. Finally, these data will incorporated into aerosol transport models for comparison with downwind sites in the USA and beyond.

  2. 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

  3. Modelling size and structure of nanoparticles formed from drying of submicron solution aerosols

    NASA Astrophysics Data System (ADS)

    Bandyopadhyay, Arpan A.; Pawar, Amol A.; Venkataraman, Chandra; Mehra, Anurag

    2015-01-01

    Drying of submicron solution aerosols, under controlled conditions, has been explored to prepare nanoparticles for drug delivery applications. A computational model of solution drop evaporation is developed to study the evolution of solute gradients inside the drop and predict the size and shell thickness of precipitating nanoparticles. The model considers evaporation as a two-stage process involving droplet shrinkage and shell growth. It was corroborated that droplet evaporation rate controls the solute distribution within a droplet and the resulting particle structure (solid or shell type). At higher gas temperatures, rapid build-up of solute near drop surface from high evaporation rates results in early attainment of critical supersaturation solubility and a steeper solute gradient, which favours formation of larger, shell-type particles. At lower gas temperatures, formation of smaller, solid nanoparticles is indicated. The computed size and shell thickness are in good agreement with experimentally prepared lipid nanoparticles. This study indicates that solid or shell structure of precipitated nanoparticles is strongly affected by evaporation rate, while initial solute concentration in the precursor solution and atomized droplet size affect shell thickness. For the gas temperatures considered, evaporative cooling leads to droplet temperature below the melting point of the lipid solute. Thus, we conclude that control over nanoparticle size and structure, of thermolabile precursor materials suitable for drug delivery, can be achieved by controlling evaporation rates, through selection of aerosol processing conditions.

  4. 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.

  5. Indoor/outdoor radon decay products associated aerosol particle-size distributions and their relation to total number concentrations.

    PubMed

    Moriizumi, Jun; Yamada, Shinya; Xu, Yang; Matsuki, Satoru; Hirao, Shigekazu; Yamazawa, Hiromi

    2014-07-01

    The activity size distributions of indoor and outdoor radioactive aerosol associated with short-lived radon decay products were observed at Nagoya, Japan, for some periods from 2010 to 2012, following the indoor observation by Mostafa et al. [Mostafa, A. M. A., Tamaki, K., Moriizumi, J., Yamazawa, H. and Iida, T. The weather dependence of particle size distribution of indoor radioactive aerosol associated with radon decay products. Radiat. Prot. Dosim. 146: (1-3), 19-22 (2011)]. The tendency of smaller indoor activity median aerodynamic diameter (AMAD) after rainfalls showed in the previous study was not consistently obtained, while the consistent tendency of less indoor radioactive particles with diameters in the accumulation mode was observed again after rainfalls. The indoor aerosols showed activity size distributions similar to the outdoor ones. Non-radioactive aerosol particle concentrations measured with a laser particle counter suggested a somewhat liner relationship with AMAD.

  6. The effect of formaldehyde and nitrogen-containing compounds on the size and volume of aerosol particles

    NASA Astrophysics Data System (ADS)

    Millage, K.; Galloway, M. M.; De Haan, D. O.

    2012-12-01

    Atmospheric aerosol can interact with clouds in many ways, often resulting in the redistribution or absorption of solar energy or changes in precipitation efficiency. Secondary organic aerosol (SOA) in particular has been linked to climate change and a reduction in the number and size of cloud particles. The reactions of nitrogen containing compounds (primary amines, amino acids and ammonium sulfate) with carbonyl compounds (such as formaldehyde and glycolaldehyde) are potential sources of SOA. Aerosol containing formaldehyde and nitrogen-containing compounds (glycine, methylamine, arginine, or ammonium sulfate) was generated from buffered solutions (pH 5.4) using a nebulizer. The aerosol was then equilibrated into a chamber containing humid air (82-84% RH), and particle sizes were measured using a SMPS system over a period of 1 hour in order to examine how the size and volume of the aerosol particles changed. Formaldehyde concentrations were varied over multiple experiments. Arginine displayed a trend of increasing relative particle size with increasing formaldehyde concentration. Ammonium sulfate and formaldehyde displayed a decrease in relative particle sizes from 0:1 to 2:1 ratios of formaldehyde to ammonium sulfate, but then an increase in relative particle sizes with increasing amounts of formaldehyde. Similarly, glycine and methylamine initially displayed decreasing relative particle sizes, until reaching a 1:1 ratio of each to formaldehyde at which point the relative particle sizes steadily increased. These effects were likely caused by the evaporation of first-generation imine products.

  7. 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

    different particle size fractions. The opportunity to obtain detailed information regarding the distribution of isocyanates in aerosols in addition to the total air levels make the DI sampler a valuable tool for studies of possible health effects in the different parts of the airways.

  8. Retrieval of Aerosol information from UV measurement by using optimal estimation method

    NASA Astrophysics Data System (ADS)

    KIM, M.; Kim, J.; Jeong, U.; Kim, W. V.; Kim, S. K.; Lee, S. D.; Moon, K. J.

    2014-12-01

    An algorithm to retrieve aerosol optical depth (AOD), single scattering albedo (SSA), and aerosol loading height is developed for GEMS (Geostationary Environment Monitoring Spectrometer) measurement. The GEMS is planned to be launched in geostationary orbit in 2018, and employs hyper-spectral imaging with 0.6 nm resolution to observe solar backscatter radiation in the UV and Visible range. In the UV range, the low surface contribution to the backscattered radiation and strong interaction between aerosol absorption and molecular scattering can be advantageous in retrieving aerosol information such as AOD and SSA [Torres et al., 2007; Torres et al., 2013; Ahn et al., 2014]. However, the large contribution of atmospheric scattering results in the increase of the sensitivity of the backward radiance to aerosol loading height. Thus, the assumption of aerosol loading height becomes important issue to obtain accurate result. Accordingly, this study focused on the simultaneous retrieval of aerosol loading height with AOD and SSA by utilizing the optimal estimation method. For the RTM simulation, the aerosol optical properties were analyzed from AERONET inversion data (level 2.0) at 46 AERONET sites over ASIA. Also, 2-channel inversion method is applied to estimate a priori value of the aerosol information to solve the Lavenberg Marquardt equation. The GEMS aerosol algorithm is tested with OMI level-1B dataset, a provisional data for GEMS measurement, and the result is compared with OMI standard aerosol product and AERONET values. The retrieved AOD and SSA show reasonable distribution compared with OMI products, and are well correlated with the value measured from AERONET. However, retrieval uncertainty in aerosol loading height is relatively larger than other results.

  9. 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

  10. 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.

  11. 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.

  12. Information Conversion, Effective Samples, and Parameter Size

    PubMed Central

    Lin, Xiaodong; Pittman, Jennifer; Clarke, Bertrand

    2008-01-01

    Consider the relative entropy between a posterior density for a parameter given a sample and a second posterior density for the same parameter, based on a different model and a different data set. Then the relative entropy can be minimized over the second sample to get a virtual sample that would make the second posterior as close as possible to the first in an informational sense. If the first posterior is based on a dependent dataset and the second posterior uses an independence model, the effective inferential power of the dependent sample is transferred into the independent sample by the optimization. Examples of this optimization are presented for models with nuisance parameters, finite mixture models, and models for correlated data. Our approach is also used to choose the effective parameter size in a Bayesian hierarchical model. PMID:19079764

  13. Volume and surface area size distribution, water mass and model fitting of GCE/CASE/WATOX marine aerosols

    NASA Astrophysics Data System (ADS)

    Kim, Y.; Sievering, H.; Boatman, J.

    1990-06-01

    As a part of the Global Change Expedition/Coordinated Air-Sea Experiment/Western Atlantic Ocean Experiment (GCE/CASE/WATOX), size distributions of marine aerosols were measured at two altitudes of about 2750 and 150 m above sea level (asl) over the size range 0.1 ˜ 32 μm. Lognormal fitting was applied to the corrected aerosol size spectra to determine the volume and surface area size distributions of the CASE-WATOX marine aerosols. Each aerosol size distribution was fitted with three lognormal distributions representing fine-, large-, and giant-particle modes. Water volume fraction and dry particle size of each aerosol size distribution were also calculated using empirical formulas for particle size as a function of relative humidity and particle type. Because of the increased influence from anthropogenic sources in the continental United States, higher aerosol volume concentrations were observed in the fine-particle mode near-shore off the east coast; 2.11 and 3.63 μm3 cm-3 for free troposphere (FT) and marine boundary layer (MBL), compared with the open-sea Bermuda area values; 0.13 and 0.74 μm3 cm-3 for FT and MBL. The large-particle mode exhibits the least variations in volume distributions between the east coast and open-sea Bermuda area, having a volume geometric median diameter (VGMD) between 1.4 and 1.6 μm and a geometric standard deviation between 1.57 and 1.68. For the giant-particle mode, larger VGMD and volume concentrations were observed for marine aerosols nearshore off the east coast than in the open-sea Bermuda area because of higher relative humidity and higher surface wind speed conditions. Wet VGMD and aerosol water volume concentrations at 15 m asl ship level were determined by extrapolating from those obtained by analysis of the CASE-WATOX aircraft aerosol data. Abundance of aerosol water in the MBL serves as an important pathway for heterogeneous conversion of SO2 in sea salt aerosol particles.

  14. 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).

  15. 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

  16. Size fractionated speciation of nitrate and sulfate aerosols in a sub-tropical industrial environment.

    PubMed

    Pandey, Sudhir Kumar; Tripathi, B D; Mishra, V K; Prajapati, S K

    2006-03-01

    Size fractionated chemical speciation of acidic aerosols were performed for ammonium sulfate, other sulfates, ammonium nitrate and other nitrates in a sub-tropical industrial area, Bina, India during December 2003 to November 2004. Analysis of variance (ANOVA) revealed highly significant temporal variations (p > .001) in the concentrations of nitrate and sulfate aerosols in all the three size fractions (fine, mid-size and coarse). Winter demonstrated utmost concentrations of ammonium sulfate, which ranged from 3.2 to 26.4 microg m(-3) in fine particles and 0.20-0.34 microg m(-3) in coarse particles. Ammonium sulfate was chiefly in fine mode (43.77% of total particulate sulfate) as compared to coarse particles (28.60% of total particulate sulfate). The major fraction Ammonium sulfate existed in different forms in atmospheric aerosols, for example NH4Fe(SO4)2, (NH4)2SO4, (NH4)3H(SO4)2 in fine particles, and (NH4)4(NO3)SO4+ in coarse particles. Other sulfate concentrations were also higher during winter ranging from 1.89 to 14.3 microg m(-3) in fine particles and 0.12-0.65microg m(-3) in coarse particles. Ammonium nitrate constituted the major fraction of total particulate nitrate all through the year and was principally in fine particles (the highest concentration in January i.e. 14.2 microg m(-3)). Other nitrates were mainly distributed in the fine particles (highest concentration in January i.e. 11.2 microg m(-3)) All the sulfate and nitrate species were mainly distributed in fine mode and have significant impact on human health.

  17. Methodology for measuring exhaust aerosol size distributions using an engine test under transient operating conditions

    NASA Astrophysics Data System (ADS)

    María Desantes, José; Bermúdez, Vicente; Molina, Santiago; Linares, Waldemar G.

    2011-11-01

    A study on the sources of variability in the measurement of particle size distribution using a two-stage dilution system and an engine exhaust particle sizer was conducted to obtain a comprehensive and repeatable methodology that can be used to measure the particle size distribution of aerosols emitted by a light-duty diesel engine under transient operating conditions. The paper includes three experimental phases: an experimental validation of the measurement method; an evaluation of the influence of sampling factors, such as dilution system pre-conditioning; and a study of the effects of the dilution conditions, such as the dilution ratio and the dilution air temperature. An examination of the type and degree of influence of each studied factor is presented, recommendations for reducing variability are given and critical parameter values are identified to develop a highly reliable measurement methodology that could be applied to further studies on the effect of engine operating parameters on exhaust particle size distributions.

  18. 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.

  19. Modelling and evaluation of size-resolved aerosol characteristics in the Eastern Mediterranean during the SUB-AERO project

    NASA Astrophysics Data System (ADS)

    Spyridaki, A.; Lazaridis, M.; Eleftheriadis, K.; Smolik, J.; Mihalopoulos, N.; Aleksandropoulou, V.

    The mesoscale air-quality modelling system UAM-AERO has been applied to study the dynamics of aerosols in the Eastern Mediterranean area. The objective of the current work is to validate the model against extensive field aerosol data for the realistic determination of the aerosol size distribution/chemical composition. The model has been studied against comprehensive aerosol size distribution data during the periods July 2000 and January 2001 at the Eastern Mediterranean area. Comparison of the model results with the field data shows that the model predicts a bimodal size distribution for the aerosol mass, which is in agreement with the experimental data, but underpredicts the total mass during the summer period, whereas the agreement for the total aerosol mass is better during the winter period. The model is capable of reproducing the size distribution characteristics of sulphate, ammonium and nitrate, but discrepancies have occurred in relation to their mass concentration during the period 26-30 July 2000. Discrepancies have also been observed in the determination of the size distribution characteristics of crustal aerosol mass and sea salt. The disagreement between the modelled results and the field data is attributed to uncertainties in the primary aerosol emissions such as sea salt and resuspended dust, and unresolved emissions from sources such as forest fires and Saharan dust episodes. It is evident that the use of the mesoscale model UAM-AERO in the Mediterranean area requires the parallel use of a regional model, which needs to incorporate emissions of Saharan dust and forest fires.

  20. The use of aerosol formation, flammability, and explosion information for heat-transfer fluid selection.

    PubMed

    Krishna, Kiran; Rogers, William J; Mannan, M Sam

    2003-11-14

    The devastating consequences of aerosol/mist explosions have been widely documented, and there are currently efforts to understand the mechanisms of formation and explosion of aerosols. Heat-transfer fluids (HTFs) are particularly susceptible to these hazards, because they are utilized under high pressures and below their flash points, making them more prone to leaking as aerosols. In fact, there is a critical need during design stages for a perception of explosion risks associated with the selection of HTFs. This paper discusses a novel scheme to integrate the knowledge of HTF aerosol formation from leaks in process equipment into the selection of HTFs during the design process. Hazards of aerosols formed from leaks are classified qualitatively using process pressure and droplet sizes.

  1. 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

  2. Indoor radon progeny aerosol size measurements in urban, suburban, and rural regions

    SciTech Connect

    Tu, K.W.; Knutson, E.O.; George, A.C. )

    1991-01-01

    By using direct and indirect methods, the authors conducted size distribution measurements of radon progeny particles in a variety of indoor environments in urban, suburban, and rural areas. The radon progeny particle size distribution owing to indoor activities has two definable source categories: (1) gas combustion from stoves and kerosene heaters - particles were found to be smaller than 0.1 {mu}m in diameter, mostly in the range 0.02-0.08 {mu}m; and (2) cigarette smoking and food frying - particles were found to be larger, in the size range 0.1-0.2 {mu}m. The radon progeny particle size distribution, without significant indoor activities, such as cooking, was found to be larger in rural areas than in urban or suburban areas. The modal diameters of the size spectra in the rural areas were two to three times larger than those in urban or suburban areas, around 0.3-0.4 bs. 0.1-0.2 {mu}m. Results obtained by applying the attachment theory to the measured number-weighted size spectra from an electrical aerosol size analyzer support this finding. These results, if confirmed by more extensive studies, will be useful for the assessment of the risk from the inhalation of radon progeny in various indoor environments.

  3. Effects of temperature and particle size on acid aerosol-induced bronchoconstriction. Report for April 1986-November 1988 (Final)

    SciTech Connect

    Sheppard, D.; Balmes, J.; Christian, D.

    1989-01-01

    The investigators exposed asthmatic subjects to aerosols of sulfuric acid or saline with varying particle size and osmolarity. Aerosols of unbuffered sulfuric acid at pH 2 did not cause bronchoconstriction in the subjects when inhaled during rest at a sulfate concentration of nearly 3 mg/cm m. Neither osmolarity nor particle size appeared to influence the lack of bronchoconstrictor effect. The investigators also studied whether there was a positive interaction between acidity and low temperature with regard to the potentiation of hypoosmolar aerosol-induced bronchoconstriction. They exposed asthmatic subjects to hypoosmolar aerosols of either sulfuric acid at pH 2 or saline at pH 5.5 at either 7 or 22 deg C. No evidence of a positive interaction between acidity and low temperature was found.

  4. 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.

  5. The importance of aerosol mixing state and size-resolved composition on CCN concentration and the variation of the importance with atmospheric aging of aerosols

    SciTech Connect

    Wang, J.; Cubison, M. J.; Aiken, A. C.; Jimenez, J. L.; Collins, D. R.

    2010-05-01

    Aerosol microphysics, chemical composition, and CCN concentrations were measured at the T0 urban supersite in Mexico City during Megacity Initiative: Local and Global Research Observations (MILAGRO) in March 2006. The aerosol size distribution and composition often showed strong diurnal variation associated with traffic emissions and aging of aerosols through coagulation and local photochemical production of secondary aerosol species. CCN concentrations (N{sub CCN}) are derived using Kohler theory from the measured aerosol size distribution and various simplified aerosol mixing state and chemical composition, and are compared to concurrent measurements at five supersaturations ranging from 0.11% to 0.35%. The influence of assumed mixing state on calculated N{sub CCN} is examined using both aerosols observed during MILAGRO and representative aerosol types. The results indicate that while ambient aerosols often consist of particles with a wide range of compositions at a given size, N{sub CCN} may be derived within {approx}20% assuming an internal mixture (i.e., particles at a given size are mixtures of all participating species, and have the identical composition) if great majority of particles has an overall {kappa} (hygroscopicity parameter) value greater than 0.1. For a non-hygroscopic particle with a diameter of 100 nm, a 3 nm coating of sulfate or nitrate is sufficient to increase its {kappa} from 0 to 0.1. The measurements during MILAGRO suggest that the mixing of non-hygroscopic primary organic aerosol (POA) and black carbon (BC) particles with photochemically produced hygroscopic species and thereby the increase of their {kappa} to 0.1 take place in a few hours during daytime. This rapid process suggests that during daytime, a few tens of kilometers away for POA and BC sources, N{sub CCN} may be derived with sufficient accuracy by assuming an internal mixture, and using bulk chemical composition. The rapid mixing also indicates that, at least for very active

  6. Characterization of aerosols in the Norwegian subarctic region (ALOMAR station): Optical properties, size distributions and nucleation events

    NASA Astrophysics Data System (ADS)

    Mogo, S.; Cachorro, V. E.; de Frutos, A. M.; Lopez, J. F.; Torres, B.; Bennouna, Y.

    2013-05-01

    During the 2008 summer, a field campaign was carried out at the Arctic Lidar Observatory for Middle Atmosphere Research, ALOMAR, on Ando/ya island close to the town of Andenes (69° 16'N, 16° 00'E, 380 m a.s.l.), approximately 300 km north of the Arctic Circle. The campaign was part of the contribution of the Atmospheric Optics Group of the Valladolid University (GOA-UVa) to the International Polar Year, in the framework of the POLARCAT (Polar Study using Aircraft, Remote Sensing, Surface Measurements and Models of Climate, Chemistry, Aerosols, and Transport) project. This GOA-UVa's field campaign has been developed to obtain experimental data for local aerosols, its optical characteristics (absorption / scattering coefficients and single scattering albedo), its size distributions and derived parameters. For this purpose, different instruments were simultaneously installed in the station facilities. These are the first measurements with this variety of information reported in the station and can be extrapolated over a wide area around.

  7. A year-long record of size-segregated aerosol composition at Halley, Antarctica

    NASA Astrophysics Data System (ADS)

    Rankin, Andrew M.; Wolff, Eric W.

    2003-12-01

    Size-segregated aerosol samples were collected with a cascade impactor at 2 week intervals for a year at the research station Halley, situated near the coast in the Weddell Sea region of Antarctica. Sea salt is a major component of aerosol throughout the year, and we estimate that at least 60% of the total sea salt arriving at Halley is from brine and frost flowers on the sea ice surface rather than open water. Chloride in sea-salt particles is depleted relative to sodium in summer, consistent with loss of HCl as sea-salt particles react with gaseous acidic species, but is enhanced in large particles in winter because of fractionation occurring during the production of new sea ice. Non-sea-salt sulphate peaks in the summer, with the majority being in small particles indicative of a gas phase origin. The distribution of methane sulphonic acid closely follows that of non-sea-salt sulphate. In the winter, non-sea-salt sulphate is frequently negative, especially on stages collecting large particle sizes, consistent with the source of sea salt during the winter being predominantly the sea ice surface rather than open water. Nitrate peaks in the spring and summer and shows some association with sea-salt particles.

  8. 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.

  9. Retrieval of the aerosol size distribution in the complex anomalous diffraction approximation

    NASA Astrophysics Data System (ADS)

    Franssens, Ghislain R.

    This contribution reports some recently achieved results in aerosol size distribution retrieval in the complex anomalous diffraction approximation (ADA) to MIE scattering theory. This approximation is valid for spherical particles that are large compared to the wavelength and have a refractive index close to 1. The ADA kernel is compared with the exact MIE kernel. Despite being a simple approximation, the ADA seems to have some practical value for the retrieval of the larger modes of tropospheric and lower stratospheric aerosols. The ADA has the advantage over MIE theory that an analytic inversion of the associated Fredholm integral equation becomes possible. In addition, spectral inversion in the ADA can be formulated as a well-posed problem. In this way, a new inverse formula was obtained, which allows the direct computation of the size distribution as an integral over the spectral extinction function. This formula is valid for particles that both scatter and absorb light and it also takes the spectral dispersion of the refractive index into account. Some details of the numerical implementation of the inverse formula are illustrated using a modified gamma test distribution. Special attention is given to the integration of spectrally truncated discrete extinction data with errors.

  10. Particle size distribution of radioactive aerosols after the Fukushima and the Chernobyl accidents.

    PubMed

    Malá, Helena; Rulík, Petr; Bečková, Vera; Mihalík, Ján; Slezáková, Miriam

    2013-12-01

    Following the Fukushima accident, a series of aerosol samples were taken between 24th March and 13th April 2011 by cascade impactors in the Czech Republic to obtain the size distribution of (131)I, (134)Cs, (137)Cs, and (7)Be aerosols. All distributions could be considered monomodal. The arithmetic means of the activity median aerodynamic diameters (AMADs) for artificial radionuclides and for (7)Be were 0.43 and 0.41 μm with GDSs 3.6 and 3.0, respectively. The time course of the AMADs of (134)Cs, (137)Cs and (7)Be in the sampled period showed a slight decrease at a significance level of 0.05, whereas the AMAD pertaining to (131)I increased at a significance level of 0.1. Results obtained after the Fukushima accident were compared with results obtained after the Chernobyl accident. The radionuclides released during the Chernobyl accident for which we determined the AMAD fell into two categories: refractory radionuclides ((140)Ba, (140)La (141)Ce, (144)Ce, (95)Zr and (95)Nb) and volatile radionuclides ((134)Cs, (137)Cs, (103)Ru, (106)Ru, (131)I, and (132)Te). The AMAD of the refractory radionuclides was approximately 3 times higher than the AMAD of the volatile radionuclides; nevertheless, the size distributions for volatile radionuclides having a mean AMAD value of 0.51 μm were very close to the distributions after the Fukushima accident.

  11. 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.

  12. Constant size, variable density aerosol particles by ultrasonic spray freeze drying.

    PubMed

    D'Addio, Suzanne M; Chan, John Gar Yan; Kwok, Philip Chi Lip; Prud'homme, Robert K; Chan, Hak-Kim

    2012-05-10

    This work provides a new understanding of critical process parameters involved in the production of inhalation aerosol particles by ultrasonic spray freeze drying to enable precise control over particle size and aerodynamic properties. A series of highly porous mannitol, lysozyme, and bovine serum albumin (BSA) particles were produced, varying only the solute concentration in the liquid feed, c(s), from 1 to 5 wt%. The particle sizes of mannitol, BSA, and lysozyme powders were independent of solute concentration, and depend only on the drop size produced by atomization. Both mannitol and lysozyme formulations showed a linear relationship between the computed Fine Particle Fraction (FPF) and the square root of c(s), which is proportional to the particle density, ρ, given a constant particle size d(g). The FPF decreased with increasing c(s) from 57.0% to 16.6% for mannitol and 44.5% to 17.2% for lysozyme. Due to cohesion, the BSA powder FPF measured by cascade impaction was less than 10% and independent of c(s). Ultrasonic spray freeze drying enables separate control over particle size, d(g), and aerodynamic size, d(a) which has allowed us to make the first experimental demonstration of the widely accepted rule d(a)=d(g)(ρ/ρ(o))(1/2) with particles of constant d(g), but variable density, ρ (ρ(o) is unit density).

  13. Characterization of water-soluble inorganic ions in size-segregated aerosols in coastal city, Xiamen

    NASA Astrophysics Data System (ADS)

    Zhao, Jinping; Zhang, Fuwang; Xu, Ya; Chen, Jinsheng

    2011-03-01

    The samples of water-soluble inorganic ions (WSIs), including anions (F-, Cl-, SO42-, NO3-) and cations (NH4+, K+, Na+, Ca2+, Mg2+) in 8 size-segregated particle matter (PM), were collected using a sampler (with 8 nominal cut-sizes ranged from 0.43 to 9.0 μm) from October 2008 to September 2009 at five sites in both polluted and background regions of a coastal city, Xiamen. The results showed that particulate matters in the fine mode (PM2.1, Dp < 2.1 μm) comprised large part of mass concentrations of aerosols, which accounted for 45.56-51.27%, 40.04-60.81%, 42.02-60.81%, and 40.46-57.07% of the total particulate mass in spring, summer, autumn, and winter, respectively. The water-soluble ionic species in the fine mode at five sampling sites varied from 15.33 to 33.82 (spring), 14.03 to 28.06 (summer), 33.47 to 72.52 (autumn), and 48.39 to 69.75 μg m- 3 (winter), respectively, which accounted for 57.30 ± 6.51% of the PM2.1 mass concentrations. Secondary pollutants of NH4+, SO42- and NO3- were the dominant contributors of WSIs, which suggested that pollutants from anthropogenic activities, such as SO2, NOx were formed in aerosols by photochemical reactions. The size distributions of Na+, Cl-, SO42- and NO3- were bimodal, peaking at 0.43-0.65 μm and 3.3-5.8 μm. Although some ions, such as NH4+ presented bimodal distributions, the coarse mode was insignificant compared to the fine mode. Ca2+ and Mg2+ exhibited unimodal distributions at all sampling sites, peaking at 2.1-3.3 μm, while K+ having a bimodal distributions with a major peak at 0.43-0.65 μm and a minor one at 3.3-4.7 μm, were used in most of samples. Seasonal and spatial variations in the size-distribution profiles suggested that meteorological conditions (seasonal patterns) and sampling locations (geographical patterns) were the main factors determining the formation of secondary aerosols and characteristics of size distributions for WSIs.

  14. 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

  15. 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

  16. Size selective isocyanate aerosols personal air sampling using porous plastic foams

    NASA Astrophysics Data System (ADS)

    Khanh Huynh, Cong; Duc, Trinh Vu

    2009-02-01

    As part of a European project (SMT4-CT96-2137), various European institutions specialized in occupational hygiene (BGIA, HSL, IOM, INRS, IST, Ambiente e Lavoro) have established a program of scientific collaboration to develop one or more prototypes of European personal samplers for the collection of simultaneous three dust fractions: inhalable, thoracic and respirable. These samplers based on existing sampling heads (IOM, GSP and cassettes) use Polyurethane Plastic Foam (PUF) according to their porosity to support sampling and separator size of the particles. In this study, the authors present an original application of size selective personal air sampling using chemical impregnated PUF to perform isocyanate aerosols capturing and derivatizing in industrial spray-painting shops.

  17. Size-resolved aerosol composition at an urban and a rural site in the Po Valley in summertime: implications for secondary aerosol formation

    NASA Astrophysics Data System (ADS)

    Sandrini, Silvia; van Pinxteren, Dominik; Giulianelli, Lara; Herrmann, Hartmut; Poulain, Laurent; Facchini, Maria Cristina; Gilardoni, Stefania; Rinaldi, Matteo; Paglione, Marco; Turpin, Barbara J.; Pollini, Francesca; Bucci, Silvia; Zanca, Nicola; Decesari, Stefano

    2016-09-01

    The aerosol size-segregated chemical composition was analyzed at an urban (Bologna) and a rural (San Pietro Capofiume) site in the Po Valley, Italy, during June and July 2012, by ion-chromatography (major water-soluble ions and organic acids) and evolved gas analysis (total and water-soluble carbon), to investigate sources and mechanisms of secondary aerosol formation during the summer. A significant enhancement of secondary organic and inorganic aerosol mass was observed under anticyclonic conditions with recirculation of planetary boundary layer air but with substantial differences between the urban and the rural site. The data analysis, including a principal component analysis (PCA) on the size-resolved dataset of chemical concentrations, indicated that the photochemical oxidation of inorganic and organic gaseous precursors was an important mechanism of secondary aerosol formation at both sites. In addition, at the rural site a second formation process, explaining the largest fraction (22 %) of the total variance, was active at nighttime, especially under stagnant conditions. Nocturnal chemistry in the rural Po Valley was associated with the formation of ammonium nitrate in large accumulation-mode (0.42-1.2 µm) aerosols favored by local thermodynamic conditions (higher relative humidity and lower temperature compared to the urban site). Nocturnal concentrations of fine nitrate were, in fact, on average 5 times higher at the rural site than in Bologna. The water uptake by this highly hygroscopic compound under high RH conditions provided the medium for increased nocturnal aerosol uptake of water-soluble organic gases and possibly also for aqueous chemistry, as revealed by the shifting of peak concentrations of secondary compounds (water-soluble organic carbon (WSOC) and sulfate) toward the large accumulation mode (0.42-1.2 µm). Contrarily, the diurnal production of WSOC (proxy for secondary organic aerosol) by photochemistry was similar at the two sites but

  18. Retrieval of optical depth and particle size distribution of tropospheric and stratospheric aerosols by means of sun photometry

    SciTech Connect

    Schmid, B.; Maetzler, C.; Kaempfer, N.; Heimo, A.

    1997-01-01

    Aerosol optical depth measurements by means of ground-based Sun photometry were made in Bern, Switzerland during two and a half years primarily to provide quantitative corrections for atmospheric effects in remotely sensed data in the visible and near-infrared spectral region. An investigation of the spatial variability of tropospheric aerosol was accomplished in the summer of 1994 in the Swiss Central Plain, a region often covered by a thick aerosol layer. Intercomparisons are made with two Sun photometers operated by the Swiss Meteorological Institute in Payerne and Davos. By means of an inversion technique, columnar particle size distributions were derived from the aerosol optical depth spectra. Effective radius, columnar surface area, and columnar mass were computed from the inversion results. Most of the spectra measured in Bern exhibit an Angstroem-law dependence. Consequently, the inverted size distributions are very close to power-law distributions. Data collected during a four month calibration campaign in fall 1993 at a high-mountain station in the Swiss Alps allowed the authors to study optical properties of stratospheric aerosol. The extinction spectra measured have shown to be still strongly influenced by remaining aerosol of the June 1991 volcanic eruptions of Mount Pinatubo. Inverted particle size distributions can be characterized by a broad monodisperse peak with a mode radius around 0.25 {micro}m. Both aerosol optical depths and effective radii had not yet returned to pre-eruption values. Comparison of retrieved aerosol optical depth, columnar surface area and mass, with the values derived from lidar observations performed in Garmisch-Partenkirchen, Southern-Germany, yielded good agreement.

  19. The particle size magnifier closing the gap between measurement of molecules, molecular clusters and aerosol particles

    NASA Astrophysics Data System (ADS)

    Mikkilä, Jyri; Lehtipalo, Katrianne; Kangasluoma, Juha; Franchin, Alessandro; Sipilä, Mikko; Jokinen, Tuija; Sarnela, Nina; Schobesberger, Siegfried; Junninen, Heikki; Kulmala, Markku; Worsnop, Douglas; Petäjä, Tuukka

    2013-05-01

    The Particle Size Magnifier lowers the cut-off size of a Condensation Particle Counter even down to about 1 nm in mobility diameter. By scanning the supersaturation also size information of the particles can be gained. We demonstrated that the PSM can detect particles starting from molecular sizes. By combining the data with newly developed mass spectrometric methods particle formation and growth can be followed molecule by molecule.

  20. Estimating Size-Resolved Surface Particulate Matter Concentrations Using MISR High-Resolution Size-Fractionated Aerosol Optical Depth

    NASA Astrophysics Data System (ADS)

    Franklin, M.; Kalashnikova, O. V.; Garay, M. J.

    2015-12-01

    There is significant public health interest in gaining a better understanding of the health effects associated with particulate matter (PM) of different composition and size, yet ground-based monitoring data for such PM species is extremely limited. Due to their spatial and temporal coverage, satellite observations of total column aerosol optical depth (AOD) have increasingly been used to estimate surface concentrations of PM. While techniques for using satellite observations of AOD to predict surface concentrations of PM2.5 have been established, predicting surface concentrations of different particle sizes and species is more challenging. The Multi-angle Imaging SpectroRadiometer (MISR) instrument has the unique capability of estimating both total column AOD as well as total column size fractionated (small, medium and large) AOD. Using MISR AOD and AOD size fractionated products derived from high-resolution (275 m) observations reported at a spatial scale of 4.4 km in combination with national Air Quality System (AQS) monitoring data over the 2008-2009 period, we examine the association between size-fractionated MISR AOD and surface measurements of PM at different sizes (PM2.5 and PM10) and PM2.5 species (EC, OC, SO42-, NH4+) over the greater Los Angeles area. While there was a limited sample size of speciated PM data, the strongest univariate association found was between AOD and PM2.5 SO42- (R2=0.76). Incorporating meteorological data from weather stations in the area resulted in improvements to the models associating AOD with PM2.5 and PM10 mass. We found that PM2.5 was best predicted by a spatio-temporal model of AOD that also included dew point temperature and wind speed (R2=0.61), and that PM10 was best predicted by a spatio-temporal model of large fraction AOD that also included atmospheric pressure and wind speed (R2=0.65). These flexibly specified spatio-temporal models enabled reliable predictions of surface PM2.5 and PM10 concentrations at a 4.4km

  1. 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.

  2. 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.

  3. 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.

  4. Aliphatic and aromatic hydrocarbons in different sized aerosols over the Mediterranean Sea: Occurrence and origin

    NASA Astrophysics Data System (ADS)

    Sicre, M. A.; Marty, J. C.; Saliot, A.; Aparicio, X.; Grimalt, J.; Albaiges, J.

    Marine aerosols were collected using a five-stage cascade impactor during the PHYCEMED II cruise in the Western Mediterranean Sea (October 1983). Their composition in aliphatic and aromatic hydrocarbons (HCs) was analyzed, representing the first time that concentrations of polynuclear aromatic HCs (PAH) are reported in relation to particle size for aerosols of remote marine areas. The HC concentrations were found to be dependent on the origin of the air masses. They were higher for air coming from North European countries than for air originating in the Atlantic and the South of Spain. The concentrations range between 7 and 14 ng m -3for n-alkanes and between 0.2 and 0.4 ng m -3for total PAH. Based on molecular criteria, several sources for these HCs have been identified: continental higher plant waxes, petroleum and pyrolysis (namely coal combustion and vehicular exhausts). Mass medium equivalent diameters (MMED) for the naturally derived n-alkanes are in the 1.79-2.53 μm range, indicating an origin related with the emission of large particles from higher plant waxes or from soil dusts. In contrast, MMED for the anthropogenic HCs, both aliphatic and aromatic, are smaller than the micron, suggesting initial emission of PAH through pyrolytic processes in the vapor phase followed by condensation onto larger sub-μm particles.

  5. 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

  6. 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

  7. A numerical study of the particle size distribution of an aerosol undergoing turbulent coagulation

    NASA Astrophysics Data System (ADS)

    Reade, Walter C.; Collins, Lance R.

    2000-07-01

    Coagulation and growth of aerosol particles subject to isotropic turbulence has been explored using direct numerical simulations. The computations follow the trajectories of 262 144 initial particles as they are convected by the turbulent flow field. Collision between two parent particles leads to the formation of a new daughter particle with the mass and momentum (but not necessarily the energy) of the parent particles. The initially monodisperse population of particles will develop a size distribution over time that is controlled by the collision dynamics. In an earlier study, Sundaram & Collins (1997) showed that collision rates in isotropic turbulence are controlled by two statistics: (i) the radial distribution of the particles and (ii) the relative velocity probability density function. Their study considered particles that rebound elastically; however, we find that the formula that they derived is equally valid in a coagulating system. However, coagulation alters the numerical values of these statistics from the values they attain for the elastic rebound case. This difference is substantial and must be taken into consideration to properly predict the evolution of the size distribution of a population of particles. The DNS results also show surprising trends in the relative breadth of the particle size distribution. First, in all cases, the standard deviation of the particle size distribution of particles with finite Stokes numbers is much larger than the standard deviation for either the zero-Stokes-number or infinite-Stokes-number limits. Secondly, for particles with small initial Stokes numbers, the standard deviation of the final particle size distribution decreases with increasing initial particle size; however, the opposite trend is observed for particles with slightly larger initial Stokes numbers. An explanation for these phenomena can be found by carefully examining the functional dependence of the radial distribution function on the particle size

  8. Size exclusion chromatography with Corona charged aerosol detector for the analysis of polyethylene glycol polymer.

    PubMed

    Kou, Dawen; Manius, Gerald; Zhan, Shangdong; Chokshi, Hitesh P

    2009-07-10

    A technique of using size exclusion chromatography (SEC) with the Corona charged aerosol detector (CAD) was developed and evaluated in comparison with refractive index (RI) and evaporative light scattering detection (ELSD) for fast screening of polyethylene glycol (PEG), a polymer used in preparing pegylated pharmaceutical compounds. These detection techniques were used in the analysis of multiple lots of PEG reagents. CAD was found to provide more accurate impurity and polydispersity profiles of PEG reagents that better differentiate their quality, while RI was not suitable for this application due to its low sensitivity and ELSD led to underestimation of the impurity and polydispersity. The accuracy of polydispersity determination by SEC-CAD was validated against a commercial reference standard of known polydispersity. The SEC-CAD technique and the observed differences between the three detectors can also be applied to polymer analysis in general.

  9. 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).

  10. 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

  11. 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.

  12. 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

  13. 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

  14. Sufficient trial size to inform clinical practice

    PubMed Central

    Manski, Charles F.; Tetenov, Aleksey

    2016-01-01

    Medical research has evolved conventions for choosing sample size in randomized clinical trials that rest on the theory of hypothesis testing. Bayesian statisticians have argued that trials should be designed to maximize subjective expected utility in settings of clinical interest. This perspective is compelling given a credible prior distribution on treatment response, but there is rarely consensus on what the subjective prior beliefs should be. We use Wald’s frequentist statistical decision theory to study design of trials under ambiguity. We show that ε-optimal rules exist when trials have large enough sample size. An ε-optimal rule has expected welfare within ε of the welfare of the best treatment in every state of nature. Equivalently, it has maximum regret no larger than ε. We consider trials that draw predetermined numbers of subjects at random within groups stratified by covariates and treatments. We report exact results for the special case of two treatments and binary outcomes. We give simple sufficient conditions on sample sizes that ensure existence of ε-optimal treatment rules when there are multiple treatments and outcomes are bounded. These conditions are obtained by application of Hoeffding large deviations inequalities to evaluate the performance of empirical success rules. PMID:27601679

  15. Investigations of Physicochemical Properties of Size-Resolved, Subsaturated, Atmospheric Aerosol Particles: Instrument Development, Field Measurements, and Data Analysis

    NASA Astrophysics Data System (ADS)

    Shingler, Taylor

    Aerosol particle properties and their impact on air quality, clouds, and the hydrologic cycle remain a critically important factor for the understanding of our atmosphere. Particle hygroscopic growth leads to impacts on direct and indirect radiative forcing properties, the likelihood for particles to act as cloud condensation nuclei, and aerosol-cloud interactions. Current instruments measuring hygroscopic growth have a number of limitations, lacking either the ability to measure size-resolved particles or process samples at a fast enough resolution to be suitable for airborne deployment. Advanced in-situ airborne particle retrieval and measurements of aerosol hygroscopic growth and scattering properties are analyzed and discussed. To improve the analysis of cloud nuclei particles, an updated counterflow virtual impact inlet was characterized and deployed during the 2011 E-PEACE field campaign. Theoretical and laboratory based cut size diameters were determined and validated against data collected from an airborne platform. In pursuit of higher quality aerosol particle hygroscopicity measurements, a newer instrument, the differential aerosol sizing and hygroscopicity probe (DASH-SP) has been developed in the recent past and only flown on a handful of campaigns. It has been proven to provide quality, rapid, size-resolved hygroscopic growth factor data, but was further improved into a smaller form factor making it easier for deployment on airborne platforms. It was flown during the 2013 SEAC4RS field campaign and the data was analyzed to composite air mass based hygroscopicity and refractive index (real portion only) statistics. Additionally, a comparison of bulk and size-resolved hygroscopic growth measurements was conducted. Significant findings include a potential particle size bias on bulk scattering measurements as well as a narrow range of ambient real portion of refractive index values. An investigation into the first reported ambient hygroscopicity

  16. 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.

  17. Comparison of the aerosol optical properties and size distribution retrieved by sun photometer with in situ measurements at midlatitude

    NASA Astrophysics Data System (ADS)

    Chauvigné, Aurélien; Sellegri, Karine; Hervo, Maxime; Montoux, Nadège; Freville, Patrick; Goloub, Philippe

    2016-09-01

    Aerosols influence the Earth radiative budget through scattering and absorption of solar radiation. Several methods are used to investigate aerosol properties and thus quantify their direct and indirect impacts on climate. At the Puy de Dôme station, continuous high-altitude near-surface in situ measurements and low-altitude ground-based remote sensing atmospheric column measurements give the opportunity to compare the aerosol extinction measured with both methods over a 1-year period. To our knowledge, it is the first time that such a comparison is realised with continuous measurements of a high-altitude site during a long-term period. This comparison addresses to which extent near-surface in situ measurements are representative of the whole atmospheric column, the aerosol mixing layer (ML) or the free troposphere (FT). In particular, the impact of multi-aerosol layers events detected using lidar backscatter profiles is analysed. A good correlation between in situ aerosol extinction coefficient and aerosol optical depth (AOD) measured by the Aerosol Robotic Network (AERONET) sun photometer is observed with a correlation coefficient around 0.80, indicating that the in situ measurements station is representative of the overall atmospheric column. After filtering for multilayer cases and correcting for each layer optical contribution (ML and FT), the atmospheric structure seems to be the main factor influencing the comparison between the two measurement techniques. When the site lies in the ML, the in situ extinction represents 45 % of the sun photometer ML extinction while when the site lies within the FT, the in situ extinction is more than 2 times higher than the FT sun photometer extinction. Moreover, the assumption of a decreasing linear vertical aerosol profile in the whole atmosphere has been tested, significantly improving the instrumental agreement. Remote sensing retrievals of the aerosol particle size distributions (PSDs) from the sun photometer

  18. Characteristics of aerosol size distribution and vertical backscattering coefficient profile during 2014 APEC in Beijing

    NASA Astrophysics Data System (ADS)

    Zhang, Jiaoshi; Chen, Zhenyi; Lu, Yihuai; Gui, Huaqiao; Liu, Jianguo; Liu, Wenqing; Wang, Jie; Yu, Tongzhu; Cheng, Yin; Chen, Yong; Ge, Baozhu; Fan, Yu; Luo, Xisheng

    2017-01-01

    During the 2014 Asia-Pacific Economic Cooperation (APEC) conference period, Beijing's air quality was greatly improved as a result of a series of tough emission control measures being implemented in Beijing and its surrounding provinces. However, a moderate haze occurred during the period of 4-5 November. In order to evaluate the emission control measures and study the formation mechanism of the haze, a comprehensive field observation based on a supersite and a lidar network was carried out from 25 October 2014 to 20 January 2015. By investigating the variations in aerosol number concentration and mean backscattering coefficient before, during and after the APEC period, it was found that number concentration of accumulation mode and coarse mode particles experienced the most significant decrease by 47% and 68%, and mean backscattering coefficient below 1 km decreased by 34% during the APEC period. Being characterized as "rapidly accumulating and rapidly dispersing", the moderate haze occurred during the APEC period was probably initiated by a wind direction change to south and an increase of wind speed to 4 m/s. Sulfur dioxide involved plume nucleation without growth in size as well as a burst of particles ranging between 100 and 300 nm were observed simultaneously during the haze episode. The elevation of sulfur dioxide concentration and particle number concentration was highly correlated with the southerly wind, signifying the contribution of regional transport. It was observed by the lidar network that the aerosol backscattering coefficient increased in sequence among three sites along the southwest pathway, suggesting that aerosols might be transported from the southwest to the northeast of Beijing with a speed of approximately 17 km/h, which agreed with the movement of air masses modeled by Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT). The dual-wavelength lidar (355 and 532 nm) observation suggested that transportation of fine particles

  19. 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

  20. 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

  1. 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.

  2. 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.

  3. 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.

  4. Complexation of trace metals in size-segregated aerosol particles at nine sites in Germany

    NASA Astrophysics Data System (ADS)

    Scheinhardt, Sebastian; Müller, Konrad; Spindler, Gerald; Herrmann, Hartmut

    2013-08-01

    The complexation of trace metal ions (TMI) was studied in size-segregated ambient aerosol particles collected at nine sites in Germany (urban, rural and coastal). Samples were analysed in terms of TMI (Fe, Mn, Cu), potential inorganic and organic ligands and pH. Using a thermodynamic model (E-AIM III), the concentrations of these compounds in the particle liquid phase were estimated. The resulting liquid phase concentrations were then used as input parameters for a speciation model (Visual MINTEQ) and the equilibrium complexation was calculated under realistic conditions. The complexation was found to be controlled by the availability of strong organic ligands, especially oxalate, whose occurrence in turn was governed by the formation of insoluble Ca-oxalate. Likewise, the pH influenced oxalate availability because it alters the concentrations of the chelating mono- and dianions. As a qualitative result, Fe3+ was found to be mainly complexed by oxalate, while Fe2+ and Mn2+ were rather associated with nitrate. Cu2+ showed mixed organic and nitrate complexation. Complexation by HULIS was only significant for Fe3+ and Cu2+ and was generally less important than other ligands like oxalate and nitrate. Oxalate was found to exist mainly in the solid phase while higher dicarboxylic acids mostly did not form complexes due to protonation. Complexation was shown to be influenced by season, air mass origin, particle size and sampling site.

  5. 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.

  6. Observations and regional modeling of aerosol optical properties, speciation and size distribution over Northern Africa and western Europe

    NASA Astrophysics Data System (ADS)

    Menut, Laurent; Siour, Guillaume; Mailler, Sylvain; Couvidat, Florian; Bessagnet, Bertrand

    2016-10-01

    The aerosol speciation and size distribution is modeled during the summer 2013 and over a large area encompassing Africa, Mediterranean and western Europe. The modeled aerosol is compared to available measurements such as the AERONET aerosol optical depth (AOD) and aerosol size distribution (ASD) and the EMEP network for surface concentrations of particulate matter PM2.5, PM10 and inorganic species (nitrate, sulfate and ammonium). The main goal of this study is to quantify the model ability to realistically model the speciation and size distribution of the aerosol. Results first showed that the long-range transport pathways are well reproduced and mainly constituted by mineral dust: spatial correlation is ≈ 0.9 for AOD and Ångström exponent, when temporal correlations show that the day-to-day variability is more difficult to reproduce. Over Europe, PM2.5 and PM10 have a mean temporal correlation of ≈ 0.4 but the lowest spatial correlation ( ≈ 0.25 and 0.62, respectively), showing that the fine particles are not well localized or transported. Being short-lived species, the uncertainties on meteorology and emissions induce these lowest scores. However, time series of PM2.5 with the speciation show a good agreement between model and measurements and are useful for discriminating the aerosol composition. Using a classification from the south (Africa) to the north (northern Europe), it is shown that mineral dust relative mass contribution decreases from 50 to 10 % when nitrate increases from 0 to 20 % and all other species, sulfate, sea salt, ammonium, elemental carbon, primary organic matter, are constant. The secondary organic aerosol contribution is between 10 and 20 % with a maximum at the latitude of the Mediterranean Sea (Spanish stations). For inorganic species, it is shown that nitrate, sulfate and ammonium have a mean temporal correlation of 0.25, 0.37 and 0.17, respectively. The spatial correlation is better (0.25, 0.5 and 0.87), showing that the mean

  7. Boundary layer aerosol size distribution, mass concentration and mineralogical composition in Morocco and at Cape Verde Islands during SAMUM I-II

    NASA Astrophysics Data System (ADS)

    Kandler, K.; Lieke, K.

    2009-04-01

    The Saharan Mineral Dust Experiment (SAMUM) is dedicated to the understanding of the radiative effects of mineral dust. Two major field experiments were performed: A first joint field campaign took place at Ouarzazate and near Zagora, southern Morocco, from May 13 to June 7, 2006. Aircraft and ground based measurements of aerosol physical and chemical properties were carried out to collect a data set of surface and atmospheric columnar information within a major dust source. This data set combined with satellite data provides the base of the first thorough columnar radiative closure tests in Saharan dust. A second field experiment was conducted during January-February 2008, in the Cape Verde Islands region, where about 300 Tg of mineral dust are transported annually from Western Africa across the Atlantic towards the Caribbean Sea and the Amazon basin. Along its transport path, the mineral dust is expected to influence significantly the radiation budget - by direct and indirect effects - of the subtropical North Atlantic. We are lacking a radiative closure in the Saharan air plume. One focus of the investigation within the trade wind region is the spatial distribution of mixed dust/biomass/sea salt aerosol and their physical and chemical properties, especially with regard to radiative effects. We report on measurements of size distributions, mass concentrations and mineralogical composition conducted at the Zagora (Morocco) and Praia (Cape Verde islands) ground stations. The aerosol size distribution was measured from 20 nm to 500

  8. Dual-beam, light-scattering interferometry for simultaneous measurements of droplet-size and velocity distributions of aerosols from commonly used nebulizers

    SciTech Connect

    Clifford, R.H.; Ishii, I.; Montaser, A. ); Meyer, G.A. )

    1990-02-15

    Dual-beam, light-scattering interferometry is introduced for simultaneous measurement of droplet-size and droplet-velocity distributions. The technique was tested in the characterization of tertiary aerosols produced by five nebulization systems (a pneumatic, an ultrasonic, and three frit-type nebulizers) used in inductively coupled plasma spectrometry. In general, the Sauter mean diameter (D{sub 3,2}) of tertiary aerosol produced by frit-type nebulizer was smaller than those of ultrasonic and pneumatic nebulizers. At higher injector gas flow, D{sub 3,2} was reduced for the pneumatic nebulizer but was increased for the ultrasonic nebulizer. At the same injector gas flow rate, droplets move slightly faster if helium is used as injector gas instead of argon. For all practical purposes, the D{sub 3,2} values measured for tertiary aerosol with dual-beam, light-scattering interferometry are comparable to the same data obtained by laser Fraunhofer diffraction. Compared to laser Fraunhofer diffraction, the proposed technique possesses two unique advantages. First, droplet velocity distribution can be measured. Second, spatially resolved information on droplet-size and velocity distributions may be obtained directly and rapidly.

  9. Impact of dust size parameterizations on aerosol burden and radiative forcing in RegCM4

    NASA Astrophysics Data System (ADS)

    Tsikerdekis, Athanasios; Zanis, Prodromos; Steiner, Allison L.; Solmon, Fabien; Amiridis, Vassilis; Marinou, Eleni; Katragkou, Eleni; Karacostas, Theodoros; Foret, Gilles

    2017-01-01

    We investigate the sensitivity of aerosol representation in the regional climate model RegCM4 for two dust parameterizations for the period 2007-2014 over the Sahara and the Mediterranean. We apply two discretization methods of the dust size distribution keeping the total mass constant: (1) the default RegCM4 4-bin approach, where the size range of each bin is calculated using an equal, logarithmic separation of the total size range of dust, using the diameter of dust particles, and (2) a newly implemented 12-bin approach with each bin defined according to an isogradient method where the size ranges are dependent on the dry deposition velocity of dust particles. Increasing the number of transported dust size bins theoretically improves the representation of the physical properties of dust particles within the same size bin. Thus, more size bins improve the simulation of atmospheric processes. The radiative effects of dust over the area are discussed and evaluated with the CALIPSO dust optical depth (DOD). This study is among the first studies evaluating the vertical profile of simulated dust with a pure dust product. Reanalysis winds from ERA-Interim and the total precipitation flux from the Climate Research Unit (CRU) observational gridded database are used to evaluate and explain the discrepancies between model and observations. The new dust binning approach increases the dust column burden by 4 and 3 % for fine and coarse particles, respectively, which increases DOD by 10 % over the desert and the Mediterranean. Consequently, negative shortwave radiative forcing (RF) is enhanced by more than 10 % at the top of the atmosphere and by 1 to 5 % on the surface. Positive longwave RF locally increases by more than 0.1 W m-2 in a large portion of the Sahara, the northern part of the Arabian Peninsula and the Middle East. The four-bin isolog method is to some extent numerically efficient, nevertheless our work highlights that the simplified representation of the four

  10. A scaling theory for the size distribution of emitted dust aerosols suggests climate models underestimate the size of the global dust cycle.

    PubMed

    Kok, Jasper F

    2011-01-18

    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.

  11. 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).

  12. 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.

  13. 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.

  14. 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

  15. Molecular size evolution of oligomers in organic aerosols collected in urban atmospheres and generated in a smog chamber.

    PubMed

    Kalberer, Markus; Sax, Mirjam; Samburova, Vera

    2006-10-01

    Only a minor fraction of the total organic aerosol mass can be resolved on a molecular level. High molecular weight compounds in organic aerosols have recently gained much attention because this class of compound potentially explains a major fraction of the unexplained organic aerosol mass. These compounds have been identified with different mass spectrometric methods, and compounds with molecular masses up to 1000 Da are found in secondary organic aerosols (SOA) generated from aromatic and terpene precursors in smog chamber experiments. Here, we apply matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) to SOA particles from two biogenic precursors, alpha-pinene and isoprene. Similar oligomer patterns are found in these two SOA systems, but also in SOA from trimethylbenzene, an anthropogenic SOA precursor. However, different maxima molecular sizes were measured for these three SOA systems. While oligomers in alpha-pinene and isoprene have sizes mostly below 600-700 Da, they grow up to about 1000 Da in trimethylbenzene-SOA. The final molecular size of the oligomers is reached early during the particle aging process, whereas other particle properties related to aging, such as the overall acid concentration or the oligomer concentration, increase continuously over a much longer time scale. This kinetic behavior of the oligomer molecular size growth can be explained by a chain growth kinetic regime. Similar oligomer mass patterns were measured in aqueous extracts of ambient aerosol samples (measured with the same technique). Distinct differences between summer and winter were observed. In summer a few single mass peaks were measured with much higher intensity than in winter, pointing to a possible difference in the formation processes of these compounds in winter and summer.

  16. 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.

  17. 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

  18. 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.

  19. 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

  20. Synthesis of nanoparticles in a flame aerosol reactor with independent and strict control of their size, crystal phase and morphology

    NASA Astrophysics Data System (ADS)

    Jiang, Jingkun; Chen, Da-Ren; Biswas, Pratim

    2007-07-01

    A flame aerosol reactor (FLAR) was developed to synthesize nanoparticles with desired properties (crystal phase and size) that could be independently controlled. The methodology was demonstrated for TiO2 nanoparticles, and this is the first time that large sets of samples with the same size but different crystal phases (six different ratios of anatase to rutile in this work) were synthesized. The degree of TiO2 nanoparticle agglomeration was determined by comparing the primary particle size distribution measured by scanning electron microscopy (SEM) to the mobility-based particle size distribution measured by online scanning mobility particle spectrometry (SMPS). By controlling the flame aerosol reactor conditions, both spherical unagglomerated particles and highly agglomerated particles were produced. To produce monodisperse nanoparticles, a high throughput multi-stage differential mobility analyser (MDMA) was used in series with the flame aerosol reactor. Nearly monodisperse nanoparticles (geometric standard deviation less than 1.05) could be collected in sufficient mass quantities (of the order of 10 mg) in reasonable time (1 h) that could be used in other studies such as determination of functionality or biological effects as a function of size.

  1. Simulation of size-segregated aerosol chemical composition over northern Italy in clear sky and wind calm conditions

    NASA Astrophysics Data System (ADS)

    Landi, T. C.; Curci, G.; Carbone, C.; Menut, L.; Bessagnet, B.; Giulianelli, L.; Paglione, M.; Facchini, M. C.

    2013-05-01

    The present article compares the outputs of the 3-D regional chemistry-transport model (CTM) CHIMERE against observations of the size-resolved aerosol chemical composition over northern Italy in clear sky and wind calm conditions. Two 4-day intensive field campaigns were carried out in July 2007 and February 2008 at three sites (urban, rural and mountain backgrounds) in the framework of the AEROCLOUDS project. Predicted levels are in reasonable agreement with observations for the urban and rural sites. Bias ranges from - 30%, for the rural site in winter, to + 38%, for the urban site during summer. In addition, the model is able to capture both the daily evolution of the bulk aerosol mass as well as its spatial gradients. Aerosol size distribution and chemical composition remain difficult to predict. The largest discrepancies were found for secondary organic aerosol (SOA) during summer and nitrates during the cold season. Compared with observations, modelled size distribution is shifted towards fine mode in winter, and towards coarse mode in summer. More accurate predictions can be achieved for both seasons by tuning the gas to particle absorption process. By reducing the SOA absorption rate by 25% at the urban sampling site in summer, the correlation between observed and simulated SOA size distributions increases from - 0.30 to + 0.70, and the bias is reduced from 200% to 0%. In winter, increasing the intra-sectional flux of particles from smaller to larger ones by a factor of 5, the Pearson correlation coefficient calculated over the nitrate size distribution goes up to + 0.85, compared to + 0.50 from CTRL, also resulting in a better agreement with the size distribution of PM10. As expected, the nitrate bulk mass concentration does not vary with respect to the base-case, and therefore nitrate overestimation remains present in the model.

  2. 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.

  3. 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

  4. 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

  5. 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.

  6. 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

  7. 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

  8. Assessment of CCN based on size-resolved hygroscopicity data: Results from urban aerosol measurements in Nagoya, Japan

    NASA Astrophysics Data System (ADS)

    Kawana, K.; Nakayama, T.; Mochida, M.

    2012-12-01

    To assess the number concentrations and the proportion of cloud condensation nuclei (CCN) and the CCN activation diameter (dact) of urban aerosols based on size-resolved hygroscopicity, the atmospheric observation was performed for 10 days at an urban site of Nagoya, Japan in September 2009. The hygroscopic growth factor (HGF) distributions of aerosol particles at 85% RH were measured using a hygroscopicity tandem differential mobility analyzer (HTDMA) system, which consists of two differential mobility analyzers (DMAs) and a condensation particle counter (CPC). The proportion of CCN in the aerosol particles exiting the first DMA of the HTDMA was measured using a CCN counter and a CPC. The number concentrations of CCN (NCCN), the ratio of NCCN to the number concentrations of condensation nuclei (NCN), and dact were predicted from the observed HTDMA data based on k-köhler theory, and they were compared with measured values. Here, measured NCCN is that obtained from the number-size distribution of aerosol particles and the size-resolved NCCN/NCN. The measured dact was obtained from a curve fit to a CCN efficiency spectrum. The dact was predicted using different two methods. Whereas one of the methods to predict dact is based on the mean hygroscopic growth factor (gmean) at each diameter, the other accounts for activation of aerosol particles at each HGF bin. The NCCN and NCCN/NCN were predicted using the latter method only. The predicted NCCN and the predicted NCCN/NCN were, respectively, on average 19% and 15% lower than the measured values. The predicted dact were on average 8% higher than the measured values by both of the methods.

  9. 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

  10. Composition and Size Characteristics of Aerosols at Gosan Super-site

    NASA Astrophysics Data System (ADS)

    Lim, S.; Lee, M.; Lee, G.; Kang, K.

    2008-12-01

    To examine the characteristics of size and compositions of particles at Gosan, ABC and ACE-Asia Super site, PM10, PM2.5 and PM1.0 aerosols were collected using Cyclone from August 2007 to June 2008. The 37mm Teflon filters and Quarts filters were used for water-soluble ions, and elemental ad organic carbon analysis. In total, 37 sets of daily sample were obtained and analyzed. The average (minimum, maximum) mass concentrations of PM10, PM2.5 and PM1.0 were respectably 29.0(7.5, 69.8), 18.2(3.9, 52.9) and 14.2(1.3, 29.5) ug/m3, respectably. The maximum concentration of PM10 mass was the highest in May, which was mainly due to Asian dust events. On the other hand, the maximum mass of PM2.5 and PM1.0 was observed in February, which seemed to be affected by pollution plumes. The median concentration of PM2.5 mass was, however, the highest in June, which is ascribed to strong photochemical activity. The average mass concentrations of NO3-, SO42- and NH4+ were 8.87, 14.41 and 2.99 ug/m3 for PM10. 8.36, 7.23 and 4.17 ug/m3 for PM2.5. 4.41, 10.67 and 2.81 ug/m3 for PM1.0. The ratio of SO42-, NH4+ and K+ concentrations to mass decreased with PM cut-off size. However NO3- showed opposite trend. The ratios of NO3- and SO42- concentrations in PM1.0 to PM10 were greater than 0.6 and less than 0.4, respectably. The results of carbonaceous measurements will be presented in the meeting.

  11. Assessment of air sampling methods and size distribution of virus-laden aerosols in outbreaks in swine and poultry farms.

    PubMed

    Alonso, Carmen; Raynor, Peter C; Goyal, Sagar; Olson, Bernard A; Alba, Anna; Davies, Peter R; Torremorell, Montserrat

    2017-03-01

    Swine and poultry viruses, such as porcine reproductive and respiratory syndrome virus (PRRSV), porcine epidemic diarrhea virus (PEDV), and highly pathogenic avian influenza virus (HPAIV), are economically important pathogens that can spread via aerosols. The reliability of methods for quantifying particle-associated viruses as well as the size distribution of aerosolized particles bearing these viruses under field conditions are not well documented. We compared the performance of 2 size-differentiating air samplers in disease outbreaks that occurred in swine and poultry facilities. Both air samplers allowed quantification of particles by size, and measured concentrations of PRRSV, PEDV, and HPAIV stratified by particle size both within and outside swine and poultry facilities. All 3 viruses were detectable in association with aerosolized particles. Proportions of positive sampling events were 69% for PEDV, 61% for HPAIV, and 8% for PRRSV. The highest virus concentrations were found with PEDV, followed by HPAIV and PRRSV. Both air collectors performed equally for the detection of total virus concentration. For all 3 viruses, higher numbers of RNA copies were associated with larger particles; however, a bimodal distribution of particles was observed in the case of PEDV and HPAIV.

  12. 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

  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. Comparison of Aerosol Optical Depth from GOES Aerosol and Smoke Product (GASP) and MODIS to AERONET AOD and IMPROVE PM2.5 Mass at Bondville, Illinois Stratified by Chemical Composition, RH, Particle Size, and Season

    NASA Astrophysics Data System (ADS)

    Green, M. C.; Kondragunta, S.; Ciren, P.

    2008-05-01

    The USEPA is interested in using satellite remote sensing data to estimate levels of PM2.5. Here we report on comparisons of aerosol optical depth (AOD) from GOES Aerosol and Smoke Product (GASP) and the Moderate Resolution Imaging Spectroradiometer (MODIS) to IMPROVE network PM2.5 mass and AErosol RObotic NETwork (AERONET) ground-based AOD. Before we compare GASP and MODIS AOD to PM2.5, we first evaluate satellite AOD using the ground-based AERONET measurements and how it varies by aerosol chemical composition and size distribution. We focus attention on the Bondville, Illinois site because there is collocated IMPROVE sampling and an AERONET site. GASP provides aerosol optical depth at 0.55 um using top of atmosphere visible channel radiance measured from GOES east and GOES west. Time resolution is typically every 30 minutes during daylight hours. MODIS provides typically once per day AOD for any given location. The IMPROVE sampler provides a 24-hour integrated sample of PM10 mass, and PM2.5 mass and elemental composition on a one day in three schedule. AERONET provides aerosol optical depth at multiple wavelengths and aerosol size distribution as well as other derived parameters such as Angstrom exponent from ground based daytime measurements. We stratified cases by RH group, major chemical component, size distribution, and season. GOES AOD correlated best with PM2.5 mass during periods with mainly small particles, moderate RH, and sulfate dominated aerosol. It correlated poorly when RH is very high or low, aerosol is primarily organic, and when coarse to fine mass ratio is high. GASP AOD also correlated best with AERONET AOD when particles are mainly fine, suggesting the aerosol model assumptions (e.g. size distribution) may need to be varied geographically for GASP to achieve better AOD results.

  15. 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

  16. 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.

  17. A study of the sea-salt chemistry using size-segregated aerosol measurements at coastal Antarctic station Neumayer

    NASA Astrophysics Data System (ADS)

    Teinilä, K.; Frey, A.; Hillamo, R.; Tülp, H. C.; Weller, R.

    2014-10-01

    Aerosol chemical and physical properties were measured in 2010 at Neumayer research station, Antarctica. Samples for chemical analysis (ion chromatography) were collected using a Teflon/Nylon filter combination (TNy) sampler, and with a multi stage low pressure impactor (SDI). Particle number concentration was measured continuously with a Grimm OPC optical particle counter. Total particle number concentration varied largely throughout the year, and the highest number concentrations for particles larger than 0.3 μm were observed simultaneously with the highest sea salt concentrations. About 50% of the sea salt aerosol mass was found in the submicron size range. Below 0.2 μm of particle aerodynamic diameter the contribution of sea salt aerosols was negligible. Further analysis showed that sea salt aerosols had undergone physico-chemical processes, either during the transportation, or during their formation. High degree of chloride depletion was observed during austral summer, when the presence of acidic gases exhibit their characteristic seasonal maximum. Apart from chloride depletion, excess chloride relating to sodium was also detected in one SDI sample, indicating actually a sodium depletion by mirabilite formation on freshly formed sea ice areas. Analysis of selected episodes showed that the concentration of sea salt particles, their modal structure, and their chemical composition is connected with their source areas, their formation mechanisms, and local transport history.

  18. 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.

  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. 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.

  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. 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.

  3. 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.

  4. In situ measurements of aerosols optical properties and number size distributions in a subarctic coastal region of Norway

    NASA Astrophysics Data System (ADS)

    Mogo, S.; Cachorro, V. E.; Lopez, J. F.; Montilla, E.; Torres, B.; Rodríguez, E.; Bennouna, Y.; de Frutos, A. M.

    2011-12-01

    In situ measurements of aerosol optical properties were made in the summer of 2008 at the ALOMAR station facility (69°16 N, 16°00 E), located at a rural site in the north of the island of Andøya (Vesterålen archipelago), approximately 300 km north of the Arctic Circle. The extended three-month campaign was part of the POLARCAT Project (Polar Study using Aircraft, Remote Sensing, Surface Measurements and Models, of Climate, Chemistry, Aerosols, and Transport) of the International Polar Year (IPY-2007-2008). Its goal was to characterize the aerosols of this sub-Arctic area, which are frequently transported to the Arctic region. The ambient light-scattering coefficient, σs (550 nm), at ALOMAR had a measured hourly mean value of 5.41 Mm-1 (StD = 3.55 Mm-1), and the light-absorption coefficient, σa (550 nm), had a measured hourly mean value of 0.40 Mm-1 (StD = 0.27 Mm-1). The scattering/absorption Ångström exponents, αs,a, are used for a detailed analysis of the variations of the spectral shape of σs,a. Whereas αs demonstrates the presence of two particle sizes corresponding to two types of aerosols, the αa demonstrates only one type of absorbing aerosol particles. Values of αa above 1 were not observed. The single-scattering albedo, ω0, ranged from 0.62 to 0.99 (mean = 0.91, StD = 0.05), and the relationships of this property to the absorption/scattering coefficients and the Ångström exponents are presented. The concentration of the particles was monitored using a scanning mobility particle sizer (SMPS), an aerodynamic particle sizer (APS) and an ultrafine condensation particle counter (UCPC). The shape of the median size distribution of the particles in the submicrometer fraction was bimodal, and the submicrometer, micrometer and total concentrations presented hourly mean values of 1277 cm3 (StD = 1563 cm3), 1 cm3 (StD = 1 cm3) and 2463 cm3 (StD = 4251 cm3), respectively. The modal correlations were investigated, and the concentration of particles

  5. 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.

  6. Black carbon mass size distributions of diesel exhaust and urban aerosols measured using differential mobility analyzer in tandem with Aethalometer

    NASA Astrophysics Data System (ADS)

    Ning, Zhi; Chan, K. L.; Wong, K. C.; Westerdahl, Dane; Močnik, Griša; Zhou, J. H.; Cheung, C. S.

    2013-12-01

    Black carbon (BC) is the dominant component of the light absorbing aerosols in the atmosphere, changing earth's radiative balance and affecting the climate. The mixing state and size distribution of atmospheric BC are largely unknown and cause uncertainties in climate models. BC is also a major component of diesel PM emissions, recently classified by World Health Organization as Category I Carcinogen, and has been associated with various adverse health effects. This study presents a novel approach of direct and continuous measurement of BC mass size distribution by tandem operation of a differential mobility spectrometry and a refined Aethalometer. A condensation particle counter was deployed in parallel with the Aethalometer to determine particle number size distribution. A wide range of particle sizes (20-600 nm) was investigated to determine the BC modal characteristics in fresh diesel engine tailpipe emissions and in different urban environments including a typical urban ambient site and a busy roadside. The study provided a demonstration of a new analytic approach and showed the evolution of BC mass size distribution from fresh engine emissions to the aged aerosols in the roadside and ambient environments. The results potentially can be used to refine the input for climate modeling to determine the effect of particle-bound atmospheric BC on the global climate.

  7. 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

  8. 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

  9. Aerosol measurements during COPE: composition, size, and sources of CCN and INPs at the interface between marine and terrestrial influences

    NASA Astrophysics Data System (ADS)

    Taylor, Jonathan W.; Choularton, Thomas W.; Blyth, Alan M.; Flynn, Michael J.; Williams, Paul I.; Young, Gillian; Bower, Keith N.; Crosier, Jonathan; Gallagher, Martin W.; Dorsey, James R.; Liu, Zixia; Rosenberg, Philip D.

    2016-09-01

    Heavy rainfall from convective clouds can lead to devastating flash flooding, and observations of aerosols and clouds are required to improve cloud parameterisations used in precipitation forecasts. We present measurements of boundary layer aerosol concentration, size, and composition from a series of research flights performed over the southwest peninsula of the UK during the COnvective Precipitation Experiment (COPE) of summer 2013. We place emphasis on periods of southwesterly winds, which locally are most conducive to convective cloud formation, when marine air from the Atlantic reached the peninsula. Accumulation-mode aerosol mass loadings were typically 2-3 µg m-3 (corrected to standard cubic metres at 1013.25 hPa and 273.15 K), the majority of which was sulfuric acid over the sea, or ammonium sulfate inland, as terrestrial ammonia sources neutralised the aerosol. The cloud condensation nuclei (CCN) concentrations in these conditions were ˜ 150-280 cm-3 at 0.1 % and 400-500 cm-3 at 0.9 % supersaturation (SST), which are in good agreement with previous Atlantic measurements, and the cloud drop concentrations at cloud base ranged from 100 to 500 cm-3. The concentration of CCN at 0.1 % SST was well correlated with non-sea-salt sulfate, meaning marine sulfate formation was likely the main source of CCN. Marine organic aerosol (OA) had a similar mass spectrum to previous measurements of sea spray OA and was poorly correlated with CCN. In one case study that was significantly different to the rest, polluted anthropogenic emissions from the southern and central UK advected to the peninsula, with significant enhancements of OA, ammonium nitrate and sulfate, and black carbon. The CCN concentrations here were around 6 times higher than in the clean cases, and the cloud drop number concentrations were 3-4 times higher. Sources of ice-nucleating particles (INPs) were assessed by comparing different parameterisations used to predict INP concentrations, using measured

  10. Information content and sensitivity of the 3β + 2α lidar measurement system for aerosol microphysical retrievals

    NASA Astrophysics Data System (ADS)

    Burton, Sharon P.; Chemyakin, Eduard; Liu, Xu; Knobelspiesse, Kirk; Stamnes, Snorre; Sawamura, Patricia; Moore, Richard H.; Hostetler, Chris A.; Ferrare, Richard A.

    2016-11-01

    There is considerable interest in retrieving profiles of aerosol effective radius, total number concentration, and complex refractive index from lidar measurements of extinction and backscatter at several wavelengths. The combination of three backscatter channels plus two extinction channels (3β + 2α) is particularly important since it is believed to be the minimum configuration necessary for the retrieval of aerosol microphysical properties and because the technological readiness of lidar systems permits this configuration on both an airborne and future spaceborne instrument. The second-generation NASA Langley airborne High Spectral Resolution Lidar (HSRL-2) has been making 3β + 2α measurements since 2012. The planned NASA Aerosol/Clouds/Ecosystems (ACE) satellite mission also recommends the 3β + 2α combination.Here we develop a deeper understanding of the information content and sensitivities of the 3β + 2α system in terms of aerosol microphysical parameters of interest. We use a retrieval-free methodology to determine the basic sensitivities of the measurements independent of retrieval assumptions and constraints. We calculate information content and uncertainty metrics using tools borrowed from the optimal estimation methodology based on Bayes' theorem, using a simplified forward model look-up table, with no explicit inversion. The forward model is simplified to represent spherical particles, monomodal log-normal size distributions, and wavelength-independent refractive indices. Since we only use the forward model with no retrieval, the given simplified aerosol scenario is applicable as a best case for all existing retrievals in the absence of additional constraints. Retrieval-dependent errors due to mismatch between retrieval assumptions and true atmospheric aerosols are not included in this sensitivity study, and neither are retrieval errors that may be introduced in the inversion process. The choice of a simplified model adds clarity to the

  11. Aerosol Mass Loading, Mixing State, Size and Number in Present Day (2000) and Future (2100): Study with the Advanced Particle Microphysics (APM) module in the Community Earth System Model (CESM)

    NASA Astrophysics Data System (ADS)

    Luo, G.; Yu, F.

    2014-12-01

    Aerosols affect the global energy budget by scattering and absorbing sunlight (direct effects) and by changing the microphysical properties, lifetime, and coverage of clouds (indirect effects). One of the key challenges in quantifying the aerosol direct and indirect effects is to deep our understanding about the size distribution, size-resolved composition, and mixing state of aerosols. However, detailed information on size distribution and mixing state is often not available or incomplete in current climate models. Here, we incorporated APM into CESM. APM is a multi-type, multi-component (sulfate, nitrate, ammonium, SOA, BC, OC, dust, and sea salt), size-resolved particle microphysics model. Online chemistry, up-to-date nucleation, oxidation aging of medium-volatile and semi-volatile organic gases, aerosol-cloud interaction with stratiform cloud, shallow convection cloud, and deep convection cloud are considered. The amounts of secondary species coated on primary particles, through condensation, coagulation, equilibrium uptake, and aqueous chemistry, are also tracked. Model results are compared with aerosol mass observed by IMPROVE/EMEP, vertical structure of global particle number from aircraft-based field campaigns, particle and cloud condensation nuclei number at ground-based stations, aerosol optical properties retrieved by several satellites. Model results can capture the major characteristics shown in these observations. With this model system, we find that global burdens of sulfate, nitrate, ammonium, BC, OC from 2000 to 2100, under scenario RCP 4.5 where total radiative forcing is stabilized before 2100, are decreased by 44%, 50%, 43%, 40%, 40%, respectively. Dust and sea salt increase slightly. Global burdens of secondary species coated on BCOC, dust, and sea salt are deceased by 34%, 30% and 60%, respectively. Global averaged aerosol number in the lower troposphere (from surface to 3 km) is significantly decreased, especially for particles smaller than

  12. SECONDARY ORGANIC AEROSOL. 3. URBAN/REGIONAL SCALE MODEL OF SIZE- AND COMPOSITION-RESOLVED AEROSOLS. (R826371C003)

    EPA Science Inventory

    The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

  13. In-Situ Light Scattering Techniques for Determining Aerosol Size Distributions and Optical Constants.

    DTIC Science & Technology

    1983-06-29

    FORM 1. REPORT NUMBER 2 GOVT ACCESSION NO. 3. RECIPIENT’S CATALOG NUMBER 4 . TITLE (and Subtitle) S. TYPE OF REPORT & PERIOD COVERED In-situ Light...DATEP esie -’ "e June 29, 1983 STriane Roy , .13. NUMBER OF PAGES k Trianele f;: k78 ’ 4 . MONITORING AGENCY NAME & ADDRESS(If different from Controlllng...experiments. The compounds tested, and examples of the - 4 - CCNTROL J -i VALVE AIR POLAR NEPHELOMETER PUMP AEROSOL GENERATOR AEROSOL L. (TSI MODEL 3050

  14. 1984-1995 Evolution of Stratospheric Aerosol Size, Surface Area, and Volume Derived by Combining SAGE II and CLAES Extinction Measurements

    NASA Technical Reports Server (NTRS)

    Russell, Philip B.; Bauman, Jill J.

    2000-01-01

    This SAGE II Science Team task focuses on the development of a multi-wavelength, multi- sensor Look-Up-Table (LUT) algorithm for retrieving information about stratospheric aerosols from global satellite-based observations of particulate extinction. The LUT algorithm combines the 4-wavelength SAGE II extinction measurements (0.385 <= lambda <= 1.02 microns) with the 7.96 micron and 12.82 micron extinction measurements from the Cryogenic Limb Array Etalon Spectrometer (CLAES) instrument, thus increasing the information content available from either sensor alone. The algorithm uses the SAGE II/CLAES composite spectra in month-latitude-altitude bins to retrieve values and uncertainties of particle effective radius R(sub eff), surface area S, volume V and size distribution width sigma(sub g).

  15. The size distribution of chemical elements of atmospheric aerosol at a semi-rural coastal site in Venice (Italy). The role of atmospheric circulation.

    PubMed

    Masiol, Mauro; Squizzato, Stefania; Ceccato, Daniele; Pavoni, Bruno

    2015-01-01

    The concentrations of selected elemental tracers were determined in the aerosol of a semi-rural coastal site near Venice (Italy). Size-segregated aerosol samples were collected using an 8-stage cascade impactor set at 15m above ground, during the cold season (late autumn and winter), when high levels of many pollutants are known to cause risks for human health. From the experimental data, information was extracted on potential pollutant sources by investigating the relationships between elements in the different size fractions. Moreover, an approach to highlight the importance of local atmospheric circulation and air mass origin in influencing the PM composition and fractional distribution is proposed. Anthropogenic elements are strongly inter-correlated in the submicrometric (<1 μm) (S, K, Mn, Cu, Fe and Zn) and intermediate mode (1-4 μm) (Mn, Cu, Zn, Ni) and their relationships highlight the presence of several sources (combustions, secondary aerosol, road traffic). In the intermediate mode, associations having geochemical significance exist between marine (Na, Cl and Mg) and crustal (Si, Mg, Ca, Al, Ti and K) elements. In the coarse mode (>4 μm) Fe and Zn are well correlated and are probably linked to tire and brake wear emissions. Regarding atmospheric circulation, results show increasing levels of elements related to pollution sources (S, K, Mn, Ni, Cu, Zn) when air masses come from Central and Eastern Europe direction and on the ground wind blows from NWN-N-NE (from mainland Venice). Low wind speed and high percentage of wind calm hours favor element accumulation in the submicrometric and intermediate modes. Furthermore, strong winds favor the formation of sea-spray and the increase of Si in the coarse mode due to the resuspension of sand fine particles.

  16. Global aerosol optical properties and application to Moderate Resolution Imaging Spectroradiometer aerosol retrieval over land

    NASA Astrophysics Data System (ADS)

    Levy, Robert C.; Remer, Lorraine A.; Dubovik, Oleg

    2007-07-01

    As more information about global aerosol properties has become available from remotely sensed retrievals and in situ measurements, it is prudent to evaluate this new information, both on its own and in the context of satellite retrieval algorithms. Using the climatology of almucantur retrievals from global Aerosol Robotic Network (AERONET) Sun photometer sites, we perform cluster analysis to determine aerosol type as a function of location and season. We find that three spherical-derived types (describing fine-sized dominated aerosol) and one spheroid-derived types (describing coarse-sized dominated aerosol, presumably dust) generally describe the range of AERONET observed global aerosol properties. The fine-dominated types are separated mainly by their single scattering albedo (ω0), ranging from nonabsorbing aerosol (ω0 ˜ 0.95) in developed urban/industrial regions, to moderately absorbing aerosol (ω0 ˜ 0.90) in forest fire burning and developing industrial regions, to absorbing aerosol (ω0 ˜ 0.85) in regions of savanna/grassland burning. We identify the dominant aerosol type at each site, and extrapolate to create seasonal 1° × 1° maps of expected aerosol types. Each aerosol type is bilognormal, with dynamic (function of optical depth) size parameters (radius, standard deviation, volume distribution) and complex refractive index. Not only are these parameters interesting in their own right, they can also be applied to aerosol retrieval algorithms, such as to aerosol retrieval over land from Moderate Resolution Imaging Spectroradiometer. Independent direct-Sun AERONET observations of spectral aerosol optical depth (τ) are consistent the spectral dependence of the models, indicating that our derived aerosol models are relevant.

  17. 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...

  18. The processing and perception of size information in speech sounds

    NASA Astrophysics Data System (ADS)

    Smith, David R. R.; Patterson, Roy D.; Turner, Richard; Kawahara, Hideki; Irino, Toshio

    2005-01-01

    There is information in speech sounds about the length of the vocal tract; specifically, as a child grows, the resonators in the vocal tract grow and the formant frequencies of the vowels decrease. It has been hypothesized that the auditory system applies a scale transform to all sounds to segregate size information from resonator shape information, and thereby enhance both size perception and speech recognition [Irino and Patterson, Speech Commun. 36, 181-203 (2002)]. This paper describes size discrimination experiments and vowel recognition experiments designed to provide evidence for an auditory scaling mechanism. Vowels were scaled to represent people with vocal tracts much longer and shorter than normal, and with pitches much higher and lower than normal. The results of the discrimination experiments show that listeners can make fine judgments about the relative size of speakers, and they can do so for vowels scaled well beyond the normal range. Similarly, the recognition experiments show good performance for vowels in the normal range, and for vowels scaled well beyond the normal range of experience. Together, the experiments support the hypothesis that the auditory system automatically normalizes for the size information in communication sounds. .

  19. 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.

  20. Information processing correlates of a size-contrast illusion.

    PubMed

    Gold, Jason M

    2014-01-01

    Perception is often influenced by context. A well-known class of perceptual context effects is perceptual contrast illusions, in which proximate stimulus regions interact to alter the perception of various stimulus attributes, such as perceived brightness, color and size. Although the phenomenal reality of contrast effects is well documented, in many cases the connection between these illusions and how information is processed by perceptual systems is not well understood. Here, we use noise as a tool to explore the information processing correlates of one such contrast effect: the Ebbinghaus-Titchener size-contrast illusion. In this illusion, the perceived size of a central dot is significantly altered by the sizes of a set of surrounding dots, such that the presence of larger surrounding dots tends to reduce the perceived size of the central dot (and vise versa). In our experiments, we first replicated previous results that have demonstrated the subjective reality of the Ebbinghaus-Titchener illusion. We then used visual noise in a detection task to probe the manner in which observers processed information when experiencing the illusion. By correlating the noise with observers' classification decisions, we found that the sizes of the surrounding contextual elements had a direct influence on the relative weight observers assigned to regions within and surrounding the central element. Specifically, observers assigned relatively more weight to the surrounding region and less weight to the central region in the presence of smaller surrounding contextual elements. These results offer new insights into the connection between the subjective experience of size-contrast illusions and their associated information processing correlates.

  1. Size distributions of n-alkanes, fatty acids and fatty alcohols in springtime aerosols from New Delhi, India.

    PubMed

    Kang, Mingjie; Fu, Pingqing; Aggarwal, Shankar G; Kumar, Sudhanshu; Zhao, Ye; Sun, Yele; Wang, Zifa

    2016-12-01

    Size-segregated aerosol samples were collected in New Delhi, India from March 6 to April 6, 2012. Homologous series of n-alkanes (C19C33), n-fatty acids (C12C30) and n-alcohols (C16C32) were measured using gas chromatography/mass spectrometry. Results showed a high-variation in the concentrations and size distributions of these chemicals during non-haze, haze, and dust storm days. In general, n-alkanes, n-fatty acids and n-alcohols presented a bimodal distribution, peaking at 0.7-1.1 μm and 4.7-5.8 μm for fine modes and coarse modes, respectively. Overall, the particulate matter mainly existed in the coarse mode (≥2.1 μm), accounting for 64.8-68.5% of total aerosol mass. During the haze period, large-scale biomass burning emitted substantial fine hydrophilic smoke particles into the atmosphere, which leads to relatively larger GMDs (geometric mean diameter) of n-alkanes in the fine mode than those during the dust storms and non-haze periods. Additionally, the springtime dust storms transported a large quantity of coarse particles from surrounding or local areas into the atmosphere, enhancing organic aerosol concentration and inducing a remarkable size shift towards the coarse mode, which are consistent with the larger GMDs of most organic compounds especially in total and coarse modes. Our results suggest that fossil fuel combustion (e.g., vehicular and industrial exhaust), biomass burning, residential cooking, and microbial activities could be the major sources of lipid compounds in the urban atmosphere in New Delhi.

  2. Size distributions of aerosols in an indoor environment with engineered nanoparticle synthesis reactors operating under different scenarios

    NASA Astrophysics Data System (ADS)

    Sahu, Manoranjan; Biswas, Pratim

    2010-03-01

    Size distributions of nanoparticles in the vicinity of synthesis reactors will provide guidelines for safe operation and protection of workers. Nanoparticle concentrations and size distributions were measured in a research academic laboratory environment with two different types of gas-phase synthesis reactors under a variety of operating conditions. The variation of total particle number concentration and size distribution at different distances from the reactor, off-design state of the fume hood, powder handling during recovery, and maintenance of reactors are established. Significant increases in number concentration were observed at all the locations during off-design conditions (i.e., failure of the exhaust system). Clearance of nanoparticles from the work environment was longer under off-design conditions (20 min) compared to that under normal hood operating conditions (4-6 min). While lower particle number concentrations are observed during operation of furnace aerosol reactors in comparison to flame aerosol reactors, the handling, processing, and maintenance operations result in elevated concentrations in the work area.

  3. 77 FR 72702 - Small Business Size Standards: Information

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-12-06

    ... From the Federal Register Online via the Government Publishing Office SMALL BUSINESS ADMINISTRATION 13 CFR Part 121 RIN 3245-AG26 Small Business Size Standards: Information AGENCY: U.S. Small Business Administration. ACTION: Final rule. SUMMARY: The United States Small Business Administration...

  4. Infrared spectroscopy of aerosols

    NASA Astrophysics Data System (ADS)

    Mentel, Th.; Sebald, H.

    2003-04-01

    In our large Aerosol Chamber at the FZ Jülich we apply HR FTIR absorption spectroscopy for the determination of trace gases. In the FTIR spectra we also observe broad absorptions of several 10 to a few 100 cm-1 widths that arise from species in the condensed aerosol phase: liquid H_2O, NO_3^-, SO_42-, HSO_4^-, or dicarboxylic acids. Moreover, the aerosol droplets caused extinctions over several 1000 cm-1 by IR scattering. This allows for in-situ observation of changes in the condensed aerosol phase e.g. on HNO_3 uptake, like the shift of the sulfate/bisulfate equilibrium or the growth by water condensation. The IR absorptions of the condensed aerosol phase provide useful extra information in process studies, if they can be quantified. Therefore the absorption cross section, respective, the absorption index which is the imaginary part of the complex refractive index is needed. We set up an aerosol flow tube in which IR spectroscopy on a 8 m light path and aerosol size distribution measurements in the range from 20 nm - 10 μm can be performed simultaneously. We measured sulfate aerosols at several relative humidities (dry, metastable, deliquescent). We will demonstrate an iterative procedure based on Mie calculations and Kramers Kronig transformation to retrieve the absorption index from the observed IR spectra and the corresponding size distribution (for dry ammonium sulfate). We will compare resulting absorption indices for aqueous sodium bisulfate aerosols at several relative humidties with thermodynamic model calculations for the Na^+/H^+/HSO_4^-/SO_42-/H_2O system.

  5. 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.

  6. 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

  7. 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

  8. 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

  9. Analysis of the vertical structure and size distribution of dust aerosols over the semi-arid region of the Loess Plateau in China

    NASA Astrophysics Data System (ADS)

    Zhou, B.; Zhang, L.; Cao, X.; Li, X.; Huang, J.; Shi, J.; Bi, J.

    2012-02-01

    Using measurements of dual-wavelength polarisation lidar, particle sizer, and nephelometer from the Semi-Arid Climate and Environment Observatory of Lanzhou University (SACOL), the properties of dust aerosol extinction coefficient, optical depth, depolarisation ratio, colour ratio, size distribution, and concentration over the semi-arid region of the Loess Plateau in north-western China are analysed in a case study of dust storms from 16-18 March 2010. The results show that dust aerosols are distributed mostly within the lower layer (below 3.0 km), with the dust aerosol extinction coefficient ranging from 0.1 to 1.0 km-1. The average optical depth and depolarisation ratio are near 0.6 and 0.3, respectively, while the colour ratio ranges from 0.8 to 1.0. The mass size distribution of dust aerosols has two peaks at 0.7 μm and 5.0 μm, respectively, while the number size distribution of dust aerosols is log-normal with a maximum near 0.8 μm. Particles in the fine mode (r ≤ 2.5 μm) are predominant in the dust storm. Their number concentration decreases while those of particles in the moderate (2.5 μm < r ≤ 10.0 μm) and coarse (10.0 μm < r ≤ 20.0 μm) modes increase. Based on Mie theory and the number size distribution of the aerosol, the dust aerosol scattering coefficient and its variation with particle size are calculated and analysed. A fairly close correlation is found with that measured by the nephelometer, for which the correlation coefficients are 0.89 and 0.94, respectively, at 520 and 700 nm. It shows a Gaussian distribution of dust aerosol scattering coefficient against effective diameter, with a fitting coefficient of 0.96 and centre diameter of 5.5 μm. The contribution percentages of aerosol within fine, moderate, and coarse modes to dust aerosol scattering coefficient are 20.95%, 62.93%, and 16.12%, respectively, meaning that PM10 is a dominant factor in the dust aerosol scattering properties.

  10. 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.

  11. Size distribution and mixing state of refractory black carbon aerosol from a coastal city in South China

    NASA Astrophysics Data System (ADS)

    Wang, Qiyuan; Huang, Ru-Jin; Zhao, Zhuzi; Zhang, Ningning; Wang, Yichen; Ni, Haiyan; Tie, Xuexi; Han, Yongming; Zhuang, Mazhan; Wang, Meng; Zhang, Jieru; Zhang, Xuemin; Dusek, Uli; Cao, Junji

    2016-11-01

    An intensive measurement campaign was conducted in the coastal city of Xiamen, China to investigate the size distribution and mixing state of the refractory black carbon (rBC) aerosol. The average rBC concentration for the campaign, measured with a ground-based single particle soot photometer (SP2), was 2.3 ± 1.7 μg m- 3, which accounted for ~ 4.3% of the PM2.5 mass. A potential source contribution function model indicated that emissions from coastal cities to the southwest were the most important source for the rBC and that shipping traffic was another likely source. The mass size distribution of the rBC particles was mono-modal and approximately lognormal, with a mass median diameter (MMD) of ~ 185 nm. Larger MMDs (~ 195 nm) occurred during polluted conditions compared with non-polluted times (~ 175 nm) due to stronger biomass burning activities during pollution episodes. Uncoated or thinly-coated particles composed the bulk of the rBC aerosol, and on average ~ 31% of the rBC was internally-mixed or thickly-coated. A positive matrix factorization model showed that organic materials were the predominant component of the rBC coatings and that mixing with nitrate increased during pollution conditions. These findings should lead to improvements in the parameterizations used to model the radiative effects of rBC.

  12. 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

  13. 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.

  14. Size-resolved aerosol and cloud condensation nuclei (CCN) properties in the remote marine South China Sea - Part 1: Observations and source classification

    NASA Astrophysics Data System (ADS)

    Atwood, Samuel A.; Reid, Jeffrey S.; Kreidenweis, Sonia M.; Blake, Donald R.; Jonsson, Haflidi H.; Lagrosas, Nofel D.; Xian, Peng; Reid, Elizabeth A.; Sessions, Walter R.; Simpas, James B.

    2017-01-01

    Ship-based measurements of aerosol and cloud condensation nuclei (CCN) properties are presented for 2 weeks of observations in remote marine regions of the South China Sea/East Sea during the southwestern monsoon (SWM) season. Smoke from extensive biomass burning throughout the Maritime Continent advected into this region during the SWM, where it was mixed with anthropogenic continental pollution and emissions from heavy shipping activities. Eight aerosol types were identified using a k-means cluster analysis with data from a size-resolved CCN characterization system. Interpretation of the clusters was supplemented by additional onboard aerosol and meteorological measurements, satellite, and model products for the region. A typical bimodal marine boundary layer background aerosol population was identified and observed mixing with accumulation mode aerosol from other sources, primarily smoke from fires in Borneo and Sumatra. Hygroscopicity was assessed using the κ parameter and was found to average 0.40 for samples dominated by aged accumulation mode smoke; 0.65 for accumulation mode marine aerosol; 0.60 in an anthropogenic aerosol plume; and 0.22 during a short period that was characterized by elevated levels of volatile organic compounds not associated with biomass burning impacts. As a special subset of the background marine aerosol, clean air masses substantially scrubbed of particles were observed following heavy precipitation or the passage of squall lines, with changes in observed aerosol properties occurring on the order of minutes. Average CN number concentrations, size distributions, and κ values are reported for each population type, along with CCN number concentrations for particles that activated at supersaturations between 0.14 and 0.85 %.

  15. On the Inversion of Light Scattering Data into Information on Aerosol Properties

    NASA Technical Reports Server (NTRS)

    Cohen, A.; Westwater, E.; Cupp, R. E.; Derr, V. E.

    1973-01-01

    The Backus-Gilbert inversion technique was applied to scattering data and calculated examples were given to ascertain its ability to recover the aerosol properties with no a-priori assumptions. In order to cheque this inversion procedure as well as other techniques (such as Daves' and Herman's et al.), a controlled experiment was performed. The experiment dealt with spherical particles the Mie scattering curves of which was measured by use of a dye-laser. These curves were used to accurately determine the refractive index of the particles. Mixtures of three different known sizes were then prepared and the scattering intensity vs. wavelength was measured at 90 deg scattering angle. The mixtures contained also various known relative concentrations of the three sizes. The analysis of the measured results will be shown and discussed.

  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. 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.

  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.

    2015-06-01

    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

  19. 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

  20. On the competition among aerosol number, size and composition in predicting CCN variability: a multi-annual field study in an urbanized desert.

    PubMed

    Crosbie, E; Youn, J-S; Balch, B; Wonaschütz, A; Shingler, T; Wang, Z; Conant, W C; Betterton, E A; Sorooshian, A

    2015-02-10

    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

  1. 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.

  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. Chemical composition and aerosol size distribution of the middle mountain range in the Nepal Himalayas during the 2009 pre-monsoon season

    NASA Astrophysics Data System (ADS)

    Shrestha, P.; Barros, A. P.; Khlystov, A.

    2010-12-01

    Aerosol particle number size distribution and chemical composition were measured at two low altitude sites, one urban and one relatively pristine valley, in Central Nepal during the 2009 pre-monsoon season (May-June). This is the first time that aerosol size distribution and chemical composition were measured simultaneously at lower elevations in the middle Himalayan region in Nepal. The aerosol size distribution was measured using a Scanning Mobility Particle Sizer (SMPS, 14-340 nm), and the chemical composition of the filter samples collected during the field campaign was analyzed in the laboratory. Teflon membrane filters were used for ion chromatography (IC) and water-soluble organic carbon and nitrogen analysis. Quartz fiber filters were used for organic carbon and elemental carbon analysis. Multi-lognormal fits to the measured aerosol size distribution indicated a consistent larger mode around 100 nm which is usually the oldest, most processed background aerosol. The smaller mode was located around 20 nm, which is indicative of fresh but not necessarily local aerosol. The diurnal cycle of the aerosol number concentration showed the presence of two peaks (early morning and evening), during the transitional periods of boundary layer growth and collapse. The increase in number concentration during the peak periods was observed for the entire size distribution. Although the possible contribution of local emissions in size ranges similar to the larger mode cannot be completely ruled out, another plausible explanation is the mixing of aged elevated aerosol in the residual layer during the morning period as suggested by previous studies. Similarly, the evening time concentration peaks when the boundary layer becomes shallow concurrent with increase in local activity. A decrease in aerosol number concentration was observed during the nighttime with the development of cold (downslope) mountain winds that force the low level warmer air in the valley to rise. The

  4. 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.

  5. How much information do extinction and backscattering measurements contain about the chemical composition of atmospheric aerosol?

    NASA Astrophysics Data System (ADS)

    Kahnert, Michael; Andersson, Emma

    2017-03-01

    We theoretically and numerically investigate the problem of assimilating multiwavelength lidar observations of extinction and backscattering coefficients of aerosols into a chemical transport model. More specifically, we consider the inverse problem of determining the chemical composition of aerosols from these observations. The main questions are how much information the observations contain to determine the particles' chemical composition, and how one can optimize a chemical data assimilation system to make maximum use of the available information. We first quantify the information content of the measurements by computing the singular values of the scaled observation operator. From the singular values we can compute the number of signal degrees of freedom, Ns, and the reduction in Shannon entropy, H. As expected, the information content as expressed by either Ns or H grows as one increases the number of observational parameters and/or wavelengths. However, the information content is strongly sensitive to the observation error. The larger the observation error variance, the lower the growth rate of Ns or H with increasing number of observations. The right singular vectors of the scaled observation operator can be employed to transform the model variables into a new basis in which the components of the state vector can be partitioned into signal-related and noise-related components. We incorporate these results in a chemical data assimilation algorithm by introducing weak constraints that restrict the assimilation algorithm to acting on the signal-related model variables only. This ensures that the information contained in the measurements is fully exploited, but not overused. Numerical tests show that the constrained data assimilation algorithm provides a solution to the inverse problem that is considerably less noisy than the corresponding unconstrained algorithm. This suggests that the restriction of the algorithm to the signal-related model variables suppresses

  6. An instrument for semi-continuous monitoring of the size-distribution of nitrate, ammonium, sulphate and chloride in aerosol

    NASA Astrophysics Data System (ADS)

    ten Brink, Harry; Otjes, René; Jongejan, Piet; Slanina, Sjaak

    An instrument was developed for semi-continuous measurement of the size-distribution of submicron nitrate, ammonium, sulphate and chloride. Novel in the instrumentation is the size-classification, which is realised with a pre-separator that consists of a set of four parallel impactors. The cut-off diameters of the impactors are at 0.18, 0.32, 0.56 and 1.0 μm. Aerosols smaller than the associated cut-off size pass the respective impactor and arrive in the detector. The manifold with impactors contains two additional lines, one open line and one containing a filter that removes all aerosols. This latter line provides an on-line field-blank. The sample air-flow is automatically switched by wide-bore ball valves to one of the six sampling lines for a period of 20 min; a measuring cycle thus takes 2 h. Down-stream of the pre-separator the sampling and automated on-line analysis of the transmitted aerosol is accomplished with a "MARGA". In this instrument steam condensation is used to grow the aerosol. The droplets formed are collected in a cyclone that drains to wet-chemical analysis systems. A wet-denuder between pre-separator and collector removes interfering gases, like nitric acid and ammonia. This enables artefact-free and thus representative semi-continuous measurement of the size-distribution of the semi-volatile (ammonium) nitrate. The novel MARGA-sizer was first used in a 1 week field-test. After modifications it was then deployed in a monitoring campaign of 2 months in the summer of 2002, at the top level of the meteo-tower of Cabauw in the centre of the Netherlands. The high location, 200 m, was chosen to obtain data on ammonium nitrate that are minimally affected by surface emissions of ammonia. The data coverage over the period was over 60%; failure of the instrumentation was mainly associated with spells of extreme solar heating of the tower and associated high temperatures inside. The average concentration of nitrate was 2.6 μg m -3, which was very

  7. 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

  8. Number-size distribution of aerosol particles and new particle formation events in tropical and subtropical Pacific Oceans

    NASA Astrophysics Data System (ADS)

    Ueda, S.; Miura, K.; Kawata, R.; Furutani, H.; Uematsu, M.; Omori, Y.; Tanimoto, H.

    2016-10-01

    Number-size distributions of aerosol particles with diameters of 10-500 nm in the marine boundary layer were observed continually onboard the R/V Hakuho Maru over the equatorial and subtropical North Pacific and South Pacific during December 2011-March 2012. Number-size distributions over each area were parameterized using a sum of up to three lognormal functions. Bi-modal size distributions with peak diameters at 30-80 nm (Aitken mode) and 100-200 nm (accumulation mode) were observed frequently. Larger peak diameters of Aitken and accumulation modes were observed over the eastern equator, where 5-day backward trajectories showed that the air masses had derived from high-chlorophyll oceanic regions without precipitation. Smaller peak diameters and low concentrations were often observed over the North Pacific. The trajectories show that such air mass originated from oceanic regions with less chlorophyll, exhibiting high precipitation frequency. New particle formation (NPF) events have often been observed over the mid-latitude eastern South Pacific with a low condensation sink (CS) and some dimethyl sulfide, although none was observed over the equator, where CS was higher. The lesser CS condition at NPF events was mostly correlated with local precipitation or precipitation along the trajectories within 1 day. These results suggest that differences of the number-size distribution and occasions of NPF events among sea areas most closely accord with precipitation along the trajectories.

  9. Human listeners attend to size information in domestic dog growls.

    PubMed

    Taylor, Anna M; Reby, David; McComb, Karen

    2008-05-01

    The acoustic features of vocalizations have the potential to transmit information about the size of callers. Most acoustic studies have focused on intraspecific perceptual abilities, but here, the ability of humans to use growls to assess the size of adult domestic dogs was tested. In a first experiment, the formants of growls were shifted to create playback stimuli with different formant dispersions (Deltaf), simulating different vocal tract lengths within the natural range of variation. Mean fundamental frequency (F0) was left unchanged and treated as a covariate. In a second experiment, F0 was resynthesized and Deltaf was left unchanged. In both experiments Deltaf and F0 influenced how participants rated the size of stimuli. Lower formant and fundamental frequencies were rated as belonging to larger dogs. Crucially, when F0 was manipulated and Deltaf was natural, ratings were strongly correlated with the actual weight of the dogs, while when Deltaf was varied and F0 was natural, ratings were not related to the actual weight. Taken together, this suggests that participants relied more heavily on Deltaf, in accordance with the fact that formants are better predictors of body size than F0.

  10. Determination of the Aerosol Size Distribution by Analytic Inversion of the Extinction Spectrum in the Complex Anomalous Diffraction Approximation

    NASA Astrophysics Data System (ADS)

    Franssens, Ghislain; de Maziére, Martine; Fonteyn, Dominique

    2000-08-01

    A new derivation is presented for the analytical inversion of aerosol spectral extinction data to size distributions. It is based on the complex analytic extension of the anomalous diffraction approximation (ADA). We derive inverse formulas that are applicable to homogeneous nonabsorbing and absorbing spherical particles. Our method simplifies, generalizes, and unifies a number of results obtained previously in the literature. In particular, we clarify the connection between the ADA transform and the Fourier and Laplace transforms. Also, the effect of the particle refractive-index dispersion on the inversion is examined. It is shown that, when Lorentz s model is used for this dispersion, the continuous ADA inverse transform is mathematically well posed, whereas with a constant refractive index it is ill posed. Further, a condition is given, in terms of Lorentz parameters, for which the continuous inverse operator does not amplify the error.

  11. Determination of the aerosol size distribution by analytic inversion of the extinction spectrum in the complex anomalous diffraction approximation.

    PubMed

    Franssens, G; De Maziére, M; Fonteyn, D

    2000-08-20

    A new derivation is presented for the analytical inversion of aerosol spectral extinction data to size distributions. It is based on the complex analytic extension of the anomalous diffraction approximation (ADA). We derive inverse formulas that are applicable to homogeneous nonabsorbing and absorbing spherical particles. Our method simplifies, generalizes, and unifies a number of results obtained previously in the literature. In particular, we clarify the connection between the ADA transform and the Fourier and Laplace transforms. Also, the effect of the particle refractive-index dispersion on the inversion is examined. It is shown that, when Lorentz's model is used for this dispersion, the continuous ADA inverse transform is mathematically well posed, whereas with a constant refractive index it is ill posed. Further, a condition is given, in terms of Lorentz parameters, for which the continuous inverse operator does not amplify the error.

  12. The MODIS Aerosol Algorithm, Products and Validation

    NASA Technical Reports Server (NTRS)

    Remer, L. A.; Kaufman, Y. J.; Tanre, D.; Mattoo, S.; Chu, D. A.; Martins, J. V.; Li, R.-R.; Ichoku, C.; Levy, R. C.; Kleidman, R. G.

    2003-01-01

    The MODerate resolution Imaging Spectroradiometer (MODIS) aboard both NASA's Terra and Aqua satellites is making near global daily observations of the earth in a wide spectral range. These measurements are used to derive spectral aerosol optical thickness and aerosol size parameters over both land and ocean. The aerosol products available over land include aerosol optical thickness at three visible wavelengths, a measure of the fraction of aerosol optical thickness attributed to the fine mode and several derived parameters including reflected spectral solar flux at top of atmosphere. Over ocean, the aerosol optical thickness is provided in seven wavelengths from 0.47 microns to 2.13 microns. In addition, quantitative aerosol size information includes effective radius of the aerosol and quantitative fraction of optical thickness attributed to the fine mode. Spectral aerosol flux, mass concentration and number of cloud condensation nuclei round out the list of available aerosol products over the ocean. The spectral optical thickness and effective radius of the aerosol over the ocean are validated by comparison with two years of AERONET data gleaned from 133 AERONET stations. 8000 MODIS aerosol retrievals colocated with AERONET measurements confirm that one-standard deviation of MODIS optical thickness retrievals fall within the predicted uncertainty of delta tauapproximately equal to plus or minus 0.03 plus or minus 0.05 tau over ocean and delta tay equal to plus or minus 0.05 plus or minus 0.15 tau over land. 271 MODIS aerosol retrievals co-located with AERONET inversions at island and coastal sites suggest that one-standard deviation of MODIS effective radius retrievals falls within delta r_eff approximately equal to 0.11 microns. The accuracy of the MODIS retrievals suggests that the product can be used to help narrow the uncertainties associated with aerosol radiative forcing of global climate.

  13. 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 ...

  14. 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.

  15. Stimulus Size Dependence of Information Transfer from Retina to Thalamus

    PubMed Central

    Uglesich, Robert; Casti, Alex; Hayot, Fernand; Kaplan, Ehud

    2009-01-01

    Relay cells in the mammalian lateral geniculate nucleus (LGN) are driven primarily by single retinal ganglion cells (RGCs). However, an LGN cell responds typically to less than half of the spikes it receives from the RGC that drives it, and without retinal drive the LGN is silent (Kaplan and Shapley, 1984). Recent studies, which used stimuli restricted to the receptive field (RF) center, show that despite the great loss of spikes, more than half of the information carried by the RGC discharge is typically preserved in the LGN discharge (Sincich et al., 2009), suggesting that the retinal spikes that are deleted by the LGN carry less information than those that are transmitted to the cortex. To determine how LGN relay neurons decide which retinal spikes to respond to, we recorded extracellularly from the cat LGN relay cell spikes together with the slow synaptic (‘S’) potentials that signal the firing of retinal spikes. We investigated the influence of the inhibitory surround of the LGN RF by stimulating the eyes with spots of various sizes, the largest of which covered the center and surround of the LGN relay cell's RF. We found that for stimuli that activated mostly the RF center, each LGN spike delivered more information than the retinal spike, but this difference was reduced as stimulus size increased to cover the RF surround. To evaluate the optimality of the LGN editing of retinal spikes, we created artificial spike trains from the retinal ones by various deletion schemes. We found that single LGN cells transmitted less information than an optimal detector could. PMID:19838326

  16. The MODIS Aerosol Algorithm, Products, Validation and Applications

    NASA Technical Reports Server (NTRS)

    Remer, L. A.; Kaufman, Y. J.; Tanre, D.

    2003-01-01

    The MODerate resolution Imaging Spectroradiometer (MODIS) currently aboard both the Terra and Aqua satellites produces a suite of products designed to characterize global aerosol distribution, optical thickness and particle size. Never before has a space-borne instrument been able to provide such detailed information, complementing field and modeling efforts to produce a comprehensive picture of aerosol characteristics. The three years of Terra-MODIS data have been validated by comparing with co-located AERONET observations of aerosol optical thickness and derivations of aerosol size parameters. Some 8000 comparison points located at 133 AERONET sites around the globe show that the MODIS aerosol optical thickness retrievals are accurate to within the pre-launch expectations. MODIS-derived size parameters are also compared with AERONET retrievals and found to agree well for fine-mode dominated aerosol regimes. Aerosol regimes dominated by dust aerosol are less accurate, attributed to what is thought to be nonsphericity. Errors due to nonsphericity will be reduced by introducing a new set of empirical phase functions, derived without any assumptions of particle shape. The major innovation that MODIS bring to the field of remote sensing of aerosol is the measure of particle size and the separation of finemode and coarsemode dominated aerosol regimes. Particle size can separate finemode man-made aerosols created during combustion, from larger natural aerosols originating from salt spray or wind erosion. This separation allows for the calculation of aerosol radiative effect and the estimation of the man-made aerosol radiative forcing. MODIS can also be used in regional studies of aerosol-cloud interaction that affect the global radiative and hydrological cycles.

  17. 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.

  18. Predictions of size-resolved aerosol concentrations of ammonium, chloride and nitrate at a bayside site using EQUISOLV II

    NASA Astrophysics Data System (ADS)

    Campbell, Scott W.; Evans, Melissa C.; Poor, Noreen D.

    Measured ambient air concentrations of ammonium, chloride and nitrate were compared with concentrations produced by EQUISOLV II, an aerosol thermodynamic equilibrium model. The monitoring equipment was located ˜50 m from Old Tampa Bay at the eastern end of the Gandy Bridge in Tampa, FL. Size-segregated ion concentrations of ammonium, sodium, potassium, calcium, magnesium, fluoride, chloride, nitrite, nitrate, sulfate and phosphate were determined from 6- and 1-day integrated cascade impactor samples obtained in May and August 2001, respectively. EQUISOLV II was initialized with these ion concentrations by size bin, and by gas phase concentrations of the volatile species, acquired with a collocated annular denuder system. The model redistributed the ions between the size bins until gas and particle concentrations reached equilibrium. The model calculated predominantly fine particle ammonium and coarse particle chloride and nitrate. For the May sampling period, when the average relative humidity was below 65%, the model predicted the formation of seven solids KNO 3, K 2SO 4, (NH 4) 2SO 4, Na 2SO 4, NaCl, NaNO 3, and CaSO 4·2H 2O. The amounts of ammonium in the fine fraction and of nitrate and chloride in the coarse fraction were predicted within the combined measurement and modeling uncertainty in the majority of cases.

  19. The self-preserving size distribution theory. I. Effects of the Knudsen number on aerosol agglomerate growth.

    PubMed

    Dekkers, Petrus J; Friedlander, Sheldon K

    2002-04-15

    Gas-phase synthesis of fine solid particles leads to fractal-like structures whose transport and light scattering properties differ from those of their spherical counterparts. Self-preserving size distribution theory provides a useful methodology for analyzing the asymptotic behavior of such systems. Apparent inconsistencies in previous treatments of the self-preserving size distributions in the free molecule regime are resolved. Integro-differential equations for fractal-like particles in the continuum and near continuum regimes are derived and used to calculate the self-preserving and quasi-self-preserving size distributions for agglomerates formed by Brownian coagulation. The results for the limiting case (the continuum regime) were compared with the results of other authors. For these cases the finite difference method was in good in agreement with previous calculations in the continuum regime. A new analysis of aerosol agglomeration for the entire Knudsen number range was developed and compared with a monodisperse model; Higher agglomeration rates were found for lower fractal dimensions, as expected from previous studies. Effects of fractal dimension, pressure, volume loading and temperature on agglomerate growth were investigated. The agglomeration rate can be reduced by decreasing volumetric loading or by increasing the pressure. In laminar flow, an increase in pressure can be used to control particle growth and polydispersity. For D(f)=2, an increase in pressure from 1 to 4 bar reduces the collision radius by about 30%. Varying the temperature has a much smaller effect on agglomerate coagulation.

  20. 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.

  1. Long-term observations of cloud condensation nuclei in the Amazon rain forest - Part 1: Aerosol size distribution, hygroscopicity, and new model parametrizations for CCN prediction

    NASA Astrophysics Data System (ADS)

    Pöhlker, Mira L.; Pöhlker, Christopher; Ditas, Florian; Klimach, Thomas; Hrabe de Angelis, Isabella; Araújo, Alessandro; Brito, Joel; Carbone, Samara; Cheng, Yafang; Chi, Xuguang; Ditz, Reiner; Gunthe, Sachin S.; Kesselmeier, Jürgen; Könemann, Tobias; Lavrič, Jošt V.; Martin, Scot T.; Mikhailov, Eugene; Moran-Zuloaga, Daniel; Rose, Diana; Saturno, Jorge; Su, Hang; Thalman, Ryan; Walter, David; Wang, Jian; Wolff, Stefan; Barbosa, Henrique M. J.; Artaxo, Paulo; Andreae, Meinrat O.; Pöschl, Ulrich

    2016-12-01

    Size-resolved long-term measurements of atmospheric aerosol and cloud condensation nuclei (CCN) concentrations and hygroscopicity were conducted at the remote Amazon Tall Tower Observatory (ATTO) in the central Amazon Basin over a 1-year period and full seasonal cycle (March 2014-February 2015). The measurements provide a climatology of CCN properties characteristic of a remote central Amazonian rain forest site.The CCN measurements were continuously cycled through 10 levels of supersaturation (S = 0.11 to 1.10 %) and span the aerosol particle size range from 20 to 245 nm. The mean critical diameters of CCN activation range from 43 nm at S = 1.10 % to 172 nm at S = 0.11 %. The particle hygroscopicity exhibits a pronounced size dependence with lower values for the Aitken mode (κAit = 0.14 ± 0.03), higher values for the accumulation mode (κAcc = 0.22 ± 0.05), and an overall mean value of κmean = 0.17 ± 0.06, consistent with high fractions of organic aerosol.The hygroscopicity parameter, κ, exhibits remarkably little temporal variability: no pronounced diurnal cycles, only weak seasonal trends, and few short-term variations during long-range transport events. In contrast, the CCN number concentrations exhibit a pronounced seasonal cycle, tracking the pollution-related seasonality in total aerosol concentration. We find that the variability in the CCN concentrations in the central Amazon is mostly driven by aerosol particle number concentration and size distribution, while variations in aerosol hygroscopicity and chemical composition matter only during a few episodes.For modeling purposes, we compare different approaches of predicting CCN number concentration and present a novel parametrization, which allows accurate CCN predictions based on a small set of input data.

  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. Particle size distribution of aerosols and associated heavy metals in kitchen environments.

    PubMed

    Gupta, Sandeep; Srivastava, Arun; Jain, V K

    2008-07-01

    Mass size distributions of total suspended particulate matter (TSPM) was measured from Sep 2002 to April 2003 in indoor kitchen environments of five locations in Jawaharlal Nehru University (JNU), New Delhi, with the help of a high volume cascade impactor. Particulate matters were separated in five different size ranges, i.e. >10.9 microm, 10.9-5.4 microm, 5.4-1.6 microm, 1.6-0.7 microm and <0.7 microm. The particle size distribution at various sites appears to follow uni-modal trend corresponding to fine particles i.e. size range <0.7 microm. The contributions of fine particles are estimated to be approximately 50% of TSPM and PM10.9, while PM10.9 comprises 80% of TSPM. Good correlations were observed between various size fractions. Regression results reveal that TSPM can adequately act as a surrogate for PM10.9 and fine particles, while PM10.9 can also act as surrogate for fine particles. The concentrations of heavy metals are found to be dominantly associated with fine particles. However, the concentration of some metals and their size distribution, to some extent is also site specific (fuel type used).

  4. 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 Astrophysics Data System (ADS)

    Bell, Shaun W.; Hansell, Richard A.; Chow, Judith C.; Tsay, Si-Chee; Hsu, N. Christina; Lin, Neng-Huei; Wang, Sheng-Hsiang; Ji, Qiang; Li, Can; Watson, John G.; Khlystov, Andrey

    2013-10-01

    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 (λ = 550 nm) 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 sulfate, nitrate, and elemental carbon. Achieving full optical closure is hampered by limitations in accounting for the role of water vapor in the system, uncertainties in the instruments and the need for further knowledge in the source apportionment of the model's major chemical components. Nonetheless, 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 sulfate 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. Consistency between the measured and modeled optical parameters serves as an

  5. 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

  6. Boundary Layer Aerosol Composition over Sierra Nevada Mountains using 9.11- and 10.59-micron CW Lidars and Modeled Backscatter from Size Distribution Data

    NASA Technical Reports Server (NTRS)

    Cutten, D. R.; Jarzembski, M. A.; Srivastava, V.; Pueschel, R. F.; Howard, S. D.; McCaul, E. W., Jr.

    2003-01-01

    An inversion technique has been developed to determine volume fractions of an atmospheric aerosol composed primarily of ammonium sulfate and ammonium nitrate and water combined with fixed concentration of elemental and organic carbon. It is based on measured aerosol backscatter obtained with 9.11 - and 10.59-micron wavelength continuous wave CO2 lidars and modeled backscatter from aerosol size distribution data. The technique is demonstrated during a flight of the NASA DC-8 aircraft over the Sierra Nevada Mountain Range, California on 19 September, 1995. Volume fraction of each component and effective complex refractive index of the composite particle were determined assuming an internally mixed composite aerosol model. The volume fractions were also used to re-compute aerosol backscatter, providing good agreement with the lidar-measured data. The robustness of the technique for determining volume fractions was extended with a comparison of calculated 2.1,-micron backscatter from size distribution data with the measured lidar data converted to 2.1,-micron backscatter using an earlier derived algorithm, verifying the algorithm as well as the backscatter calculations.

  7. 40 CFR Table F-4 to Subpart F of... - Estimated Mass Concentration Measurement of PM2.5 for Idealized Coarse Aerosol Size Distribution

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 6 2012-07-01 2012-07-01 false Estimated Mass Concentration... Concentration Measurement of PM2.5 for Idealized Coarse Aerosol Size Distribution Particle Aerodynamic Diameter (µm) Test Sampler Fractional Sampling Effectiveness Interval Mass Concentration (µg/m3) Estimated...

  8. 40 CFR Table F-4 to Subpart F of... - Estimated Mass Concentration Measurement of PM 2.5 for Idealized Coarse Aerosol Size Distribution

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 6 2013-07-01 2013-07-01 false Estimated Mass Concentration... Concentration Measurement of PM 2.5 for Idealized Coarse Aerosol Size Distribution Particle Aerodynamic Diameter (µm) Test Sampler Fractional Sampling Effectiveness Interval Mass Concentration (µg/m 3)...

  9. 40 CFR Table F-6 to Subpart F of... - Estimated Mass Concentration Measurement of PM2.5 for Idealized Fine Aerosol Size Distribution

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 6 2012-07-01 2012-07-01 false Estimated Mass Concentration... Concentration Measurement of PM2.5 for Idealized Fine Aerosol Size Distribution Particle Aerodynamic Diameter (µm) Test Sampler Fractional Sampling Effectiveness Interval Mass Concentration (µg/m3) Estimated...

  10. 40 CFR Table F-4 to Subpart F of... - Estimated Mass Concentration Measurement of PM 2.5 for Idealized Coarse Aerosol Size Distribution

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 6 2014-07-01 2014-07-01 false Estimated Mass Concentration... Concentration Measurement of PM 2.5 for Idealized Coarse Aerosol Size Distribution Particle Aerodynamic Diameter (µm) Test Sampler Fractional Sampling Effectiveness Interval Mass Concentration (µg/m3) Estimated...

  11. 40 CFR Table F-5 to Subpart F of... - Estimated Mass Concentration Measurement of PM 2.5 for Idealized “Typical” Coarse Aerosol Size...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 6 2013-07-01 2013-07-01 false Estimated Mass Concentration... 53—Estimated Mass Concentration Measurement of PM 2.5 for Idealized “Typical” Coarse Aerosol Size... Concentration (µg/m 3) Estimated Mass Concentration Measurement (µg/m 3) Ideal Sampler Fractional...

  12. 40 CFR Table F-6 to Subpart F of... - Estimated Mass Concentration Measurement of PM 2.5 for Idealized Fine Aerosol Size Distribution

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 6 2013-07-01 2013-07-01 false Estimated Mass Concentration... Concentration Measurement of PM 2.5 for Idealized Fine Aerosol Size Distribution Particle Aerodynamic Diameter (µm) Test Sampler Fractional Sampling Effectiveness Interval Mass Concentration (µg/m 3)...

  13. 40 CFR Table F-6 to Subpart F of... - Estimated Mass Concentration Measurement of PM 2.5 for Idealized Fine Aerosol Size Distribution

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 6 2014-07-01 2014-07-01 false Estimated Mass Concentration... Concentration Measurement of PM 2.5 for Idealized Fine Aerosol Size Distribution Particle Aerodynamic Diameter (µm) Test Sampler Fractional Sampling Effectiveness Interval Mass Concentration (µg/m3) Estimated...

  14. 40 CFR Table F-5 to Subpart F of... - Estimated Mass Concentration Measurement of PM2.5 for Idealized “Typical” Coarse Aerosol Size...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 6 2012-07-01 2012-07-01 false Estimated Mass Concentration... 53—Estimated Mass Concentration Measurement of PM2.5 for Idealized “Typical” Coarse Aerosol Size... Concentration (µg/m3) Estimated Mass Concentration Measurement (µg/m3) Ideal Sampler Fractional...

  15. 40 CFR Table F-5 to Subpart F of... - Estimated Mass Concentration Measurement of PM 2.5 for Idealized “Typical” Coarse Aerosol Size...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 6 2014-07-01 2014-07-01 false Estimated Mass Concentration... 53—Estimated Mass Concentration Measurement of PM 2.5 for Idealized “Typical” Coarse Aerosol Size... Concentration (µg/m3) Estimated Mass Concentration Measurement (µg/m3) Ideal Sampler Fractional...

  16. POLYCYCLIC AROMATIC HYDROCARBON (PAH) SIZE DISTRIBUTIONS IN AEROSOLS FROM APPLIANCES OF RESIDENTIAL WOOD COMBUSTION AS DETERMINED BY DIRECT THERMAL DESORPTION - GC/MS

    EPA Science Inventory

    The paper describesd a direct thermal desorption (TDS) approach to determine the PAH composition (MW = 202-302 amu) in size-segregated aerosols from residential wood combustion (RWC). Six combustion tests are performed with two highly available wood fuel varieties, Douglas-fir (P...

  17. Calibration method for a photoacoustic system for real time source apportionment of light absorbing carbonaceous aerosol based on size distribution measurements

    NASA Astrophysics Data System (ADS)

    Utry, Noemi; Ajtai, Tibor; Pinter, Mate; Orvos, Peter I.; Szabo, Gabor; Bozoki, Zoltan

    2016-04-01

    In this study, we introduce a calibration method with which sources of light absorbing carbonaceous particulate matter (LAC) can be apportioned in real time based on multi wavelength optical absorption measurements with a photoacoustic system. The method is primary applicable in wintry urban conditions when LAC is dominated by traffic and biomass burning. The proposed method was successfully tested in a field campaign in the city center of Szeged, Hungary during winter time where the dominance of traffic and wood burning aerosol has been experimentally demonstrated earlier. With the help of the proposed calibration method a relationship between the measured Aerosol Angström Exponent (AAE) and the number size distribution can be deduced. Once the calibration curve is determined, the relative strength of the two pollution sources can be deduced in real time as long as the light absorbing fraction of PM is exclusively related to traffic and wood burning. This assumption is indirectly confirmed in the presented measurement campaign by the fact that the measured size distribution is composed of two unimodal size distributions identified to correspond to traffic and wood burning aerosols. The proposed method offers the possibility of replacing laborious chemical analysis with simple in-situ measurement of aerosol size distribution data.

  18. Constraining climate model simulations of aerosol size distributions over the North Pacific and North America using in-situ airborne measurements

    NASA Astrophysics Data System (ADS)

    McNaughton, Cameron Stuart

    The effect of aerosols on climate is poorly understood compared to green house gases. Aerosols can scatter and/or absorb solar radiation (the "direct effect") and modify cloud properties (the "indirect effect"), affecting Earth's radiation balance and hydrological cycle. Aerosol lifetimes vary from minutes to weeks in the Earth's atmosphere, so they are heterogeneously distributed in both time and space. Over longer time scales, aerosols can influence climate through sulfur (e.g. CLAW Hypothesis) and iron (e.g. Iron Hypothesis) biogeochemical cycling. Determination of natural and anthropogenic aerosol effects on past and future climate can only be achieved using global climate models (GCM's). Satellites allow global measurements of the present-day atmosphere, but require calibration/validation by observations in-situ. Ground- and ship-based observations are confined to the surface boundary layer which can be decoupled from overlying layers and the free troposphere. Here I use in-situ aircraft measurements from five NASA and NSF airborne field campaigns conducted over the North Pacific and North America between 2001 and 2006 to establish a reduced set of airmass types that are stratified vertically, by source region and according to processes governing their characteristics. For each airmass type the aerosol size distribution, mixing state, optical properties and chemical composition are summarized and discussed. In this study I found, (i) parameterizations of background free troposphere aerosol overestimate extinction by ˜50%, minimizing the differences between pre-industrial versus contemporary radiative forcing, (i) meteorological model errors in water vapour mixing ratio can overwhelm the influence of composition-dependent aerosol hygroscopicity on radiating forcing, (iii) aerosol number in convective cloud outflow over North America in summer were reduced by 1/e after ˜2 days with no detectable increase in aerosol mass or decrease in SO2, illustrating the

  19. An algorithm for hyperspectral remote sensing of aerosols: theoretical framework, information content analysis and application to GEO-TASO

    NASA Astrophysics Data System (ADS)

    Hou, W.; Wang, J.; Xu, X.; Leitch, J. W.; Delker, T.; Chen, G.

    2015-12-01

    This paper includes a series of studies that aim to develop a hyperspectral remote sensing technique for retrieving aerosol properties from a newly developed instrument GEO-TASO (Geostationary Trance gas and Aerosol Sensor Optimization) that measures the radiation at 0.4-0.7 wavelengths at spectral resolution of 0.02 nm. GEOS-TASO instrument is a prototype instrument of TEMPO (Tropospheric Emissions: Monitoring of Pollution), which will be launched in 2022 to measure aerosols, O3, and other trace gases from a geostationary orbit over the N-America. The theoretical framework of optimized inversion algorithm and the information content analysis such as degree of freedom for signal (DFS) will be discussed for hyperspectral remote sensing in visible bands, as well as the application to GEO-TASO, which has mounted on the NASA HU-25C aircraft and gathered several days' of airborne hyperspectral data for our studies. Based on the optimization theory and different from the traditional lookup table (LUT) retrieval technique, our inversion method intends to retrieve the aerosol parameters and surface reflectance simultaneously, in which UNL-VRTM (UNified Linearized Radiative Transfer Model) is employed for forward model and Jacobians calculation, meanwhile, principal component analysis (PCA) is used to constrain the hyperspectral surface reflectance.The information content analysis provides the theoretical analysis guidance about what kind of aerosol parameters could be retrieved from GeoTASO hyperspectral remote sensing to the practical inversion study. Besides, the inversion conducted iteratively until the modeled spectral radiance fits with GeoTASO measurements by a Quasi-Newton method called L-BFGS-B (Large scale BFGS Bound constrained). Finally, the retrieval results of aerosol optical depth and other aerosol parameters are compared against those retrieved by AEROENT and/or in situ measurements such as DISCOVER-AQ during the aircraft campaign.

  20. The influence of wildfires on aerosol size distributions in rural areas.

    PubMed

    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.

  1. 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

  2. Size distribution, composition and origin of the submicron aerosol in the marine boundary layer during the eastern Mediterranean "SUB-AERO" experiment

    NASA Astrophysics Data System (ADS)

    Eleftheriadis, K.; Colbeck, I.; Housiadas, C.; Lazaridis, M.; Mihalopoulos, N.; Mitsakou, C.; Smolík, J.; Ždímal, V.

    A period of intensive physical and chemical aerosol characterisation measurements was held over 5 days during July 2000 as part of the European SUB-AERO experiment.. Concurrent measurements were performed at the Finokalia remote coastal site on the island of Crete (Greece) and onboard the R/V " Aegaeon" which cruised in south part of the Aegean Sea northwards of Crete. The objective of the study was to investigate the spatial and temporal variability of microphysical parameters of the submicron aerosol and their dependence on airmass origin and chemical composition. The results reflect the submicron aerosol properties during airmass transport from the north including Europe and the Balkans and are in line with other studies on the aerosol properties of polluted continental air entering the marine boundary layer (MBL). Concentrations of submicron particulate matter (PM) mass were relatively higher at sea (20 μg m -3) compared to the coastal site (16 μg m -3). Concentrations of both organic carbon and sulphate, being the major water soluble component, were also higher at sea than at land. The high concentrations of ammonium and those of the water soluble organics, such as oxalate, can be attributed to emissions from mainland forest fires. The submicron aerosol number size distribution was unimodal with mobility mean diameters ( dg) ranging from 98 to 144 μm and standard deviations ( σg) from 1.56 to 1.9. Aerosol number concentrations at Finokalia were at least 50% lower especially when R/V Aegaeon sampled polluted air, but the modal parameters of the size distribution were very similar ( dg: 111-120, σg: 1.55-1.91). The surface MBL, under these conditions, was an aerosol rich environment where aerosol particles were transported both by the surface wind, advected from higher layers, chemically processed by interactions with gaseous precursors and physically altered by water vapour. The number to volume ratio for the submicrometer aerosol fraction reflected the

  3. Type of Aerosols Determination Over Malaysia by AERONET Data

    NASA Astrophysics Data System (ADS)

    Lim, H.; Tan, F.; Abdullah, K.; Holben, B. N.

    2013-12-01

    Aerosols are one of the most interesting studies by the researchers due to the complicated of their characteristic and are not yet well quantified. Besides that there still have huge uncertainties associated with changes in Earth's radiation budget. The previous study by other researchers shown a lot of difficulties and challenges in quantifying aerosol influences arise. As well as the heterogeneity from the aerosol loading and properties: spatial, temporal, size, and composition. In this study, we were investigated the aerosol characteristics over two regions with different environmental conditions and aerosol sources contributed. The study sites are Penang and Kuching, Malaysia where ground-based AErosol RObotic NETwork (AERONET) sun-photometer was deployed. The types of the aerosols for both study sites were identified by analyzing aerosol optical depth, angstrom parameter and spectral de-convolution algorithm product from sun-photometer. The analysis was carried out associated with the in-situ meteorological data of relative humidity, visibility and air pollution index. The major aerosol type over Penang found in this study was hydrophobic aerosols. Whereas the hydrophilic type of the aerosols was highly distributed in Kuching. The major aerosol size distributions for both regions were identified in this study. The result also shows that the aerosol optical properties were affected by the types and characteristic of aerosols. Therefore, in this study we generated an algorithm to determine the aerosols in Malaysia by considered the environmental factors. From this study we found that the source of aerosols should always being consider in to retrieve the accurate information of aerosol for air quality study.

  4. Individual Aerosol Particles from Biomass Burning in Southern Africa. 1; Compositions and Size Distributions of Carbonaceous Particles

    NASA Technical Reports Server (NTRS)

    Posfai, Mihaly; Simonics, Renata; Li, Jia; Hobbs, Peter V.; Buseck, Peter R.

    2003-01-01

    Individual aerosol particles in smoke plumes from biomass fires and in regional hazes in southern Africa were studied using analytical transmission electron microscopy (TEM), which allowed detailed characterization of carbonaceous particle types in smoke and determination of changes in particle properties and concentrations during smoke aging. Based on composition, morphology, and microstructure, three distinct types of carbonaceous particles were present in the smoke: organic particles with inorganic (K-salt) inclusions, tar ball particles, and soot. The relative number concentrations of organic particles were largest in young smoke, whereas tar balls were dominant in a slightly aged (1 hour) smoke from a smoldering fire. Flaming fires emitted relatively more soot particles than smoldering fires, but soot was a minor constituent of all studied plumes. Further aging caused the accumulation of sulfate on organic and soot particles, as indicated by the large number of internally mixed organic/sulfate and soot/sulfate particles in the regional haze. Externally mixed ammonium sulfate particles dominated in the boundary layer hazes, whereas organic/sulfate particles were the most abundant type in the upper hazes. Apparently, elevated haze layers were more strongly affected by biomass smoke than those within the boundary layer. Based on size distributions and the observed patterns of internal mixing, we hypothesize that organic and soot particles are the cloud-nucleating constituents of biomass smoke aerosols. Sea-salt particles dominated in the samples taken in stratus clouds over the Atlantic Ocean, off the coast of Namibia, whereas a distinct haze layer above the clouds consisted of aged biomass smoke particles.

  5. Individual aerosol particles from biomass burning in southern Africa: 1. Compositions and size distributions of carbonaceous particles

    NASA Astrophysics Data System (ADS)

    Pósfai, MiháLy; Simonics, RenáTa; Li, Jia; Hobbs, Peter V.; Buseck, Peter R.

    2003-07-01

    Individual aerosol particles in smoke plumes from biomass fires and in regional hazes in southern Africa were studied using analytical transmission electron microscopy (TEM), which allowed detailed characterization of carbonaceous particle types in smoke and determination of changes in particle properties and concentrations during smoke aging. Based on composition, morphology, and microstructure, three distinct types of carbonaceous particles were present in the smoke: organic particles with inorganic (K-salt) inclusions, "tar ball" particles, and soot. The relative number concentrations of organic particles were largest in young smoke, whereas tar balls were dominant in a slightly aged (˜1 hour) smoke from a smoldering fire. Flaming fires emitted relatively more soot particles than smoldering fires, but soot was a minor constituent of all studied plumes. Further aging caused the accumulation of sulfate on organic and soot particles, as indicated by the large number of internally mixed organic/sulfate and soot/sulfate particles in the regional haze. Externally mixed ammonium sulfate particles dominated in the boundary layer hazes, whereas organic/sulfate particles were the most abundant type in the upper hazes. Apparently, elevated haze layers were more strongly affected by biomass smoke than those within the boundary layer. Based on size distributions and the observed patterns of internal mixing, we hypothesize that organic and soot particles are the cloud-nucleating constituents of biomass smoke aerosols. Sea-salt particles dominated in the samples taken in stratus clouds over the Atlantic Ocean, off the coast of Namibia, whereas a distinct haze layer above the clouds consisted of aged biomass smoke particles.

  6. Aerosol- and updraft-limited regimes of cloud droplet formation: influence of particle number, size and hygroscopicity on the activation of cloud condensation nuclei (CCN)

    NASA Astrophysics Data System (ADS)

    Reutter, P.; Su, H.; Trentmann, J.; Simmel, M.; Rose, D.; Gunthe, S. S.; Wernli, H.; Andreae, M. O.; Pöschl, U.

    2009-09-01

    We have investigated the formation of cloud droplets under pyro-convective conditions using a cloud parcel model with detailed spectral microphysics and with the κ-Köhler model approach for efficient and realistic description of the cloud condensation nucleus (CCN) activity of aerosol particles. Assuming a typical biomass burning aerosol size distribution (accumulation mode centred at 120 nm), we have calculated initial cloud droplet number concentrations (NCD) for a wide range of updraft velocities (w=0.25-20 m s-1) and aerosol particle number concentrations (NCN=200-105 cm-3) at the cloud base. Depending on the ratio between updraft velocity and particle number concentration (w/NCN), we found three distinctly different regimes of CCN activation and cloud droplet formation: (1) An aerosol-limited regime that is characterized by high w/NCN ratios (>≈10-3 m s-1 cm3), high maximum values of water vapour supersaturation (Smax>≈0.5%), and high activated fractions of aerosol particles (NCN/NCN>≈90%). In this regime NCD is directly proportional to NCN and practically independent of w. (2) An updraft-limited regime that is characterized by low w/NCN ratios (<≈10-4 m s-1 cm3), low maximum values of water vapour supersaturation (Smax<≈0.2%), and low activated fractions of aerosol particles (NCD/NCN<≈20%). In this regime NCD is directly proportional to w and practically independent of NCN. (3) An aerosol- and updraft-sensitive regime (transitional regime), which is characterized by parameter values in between the two other regimes and covers most of the conditions relevant for pyro-convection. In this regime NCD depends non-linearly on both NCN and w. In sensitivity studies we have tested the influence of aerosol particle size distribution and hygroscopicity on NCD. Within the range of effective hygroscopicity parameters that is characteristic for continental atmospheric aerosols (κ≈0.05-0.6), we found that NCD depends rather weakly on the actual value of κ

  7. The effects of particle-size distribution and chloride depletion of sea-salt aerosols on estimating atmospheric deposition at a coastal site

    NASA Astrophysics Data System (ADS)

    Harkel, M. J. Ten

    Estimating atmospheric deposition in a coastal region cannot be done without taking care of the size distribution and amount of chloride depletion of sea-salt aerosols. Size distribution of the dry deposition particles is important when the approach of Ulrich (1983, Effects of Accumulation of Air Pollutants in Forest Ecosystems, pp. 33-45. Reidel, Dordrecht) is used to estimate total atmospheric deposition levels in a coastal area. A sodium deposition model demonstrated that the presumption of an equal size of sodium aerosols and chloride, potassium, magnesium and calcium aerosols is not valid in the coastal zone. Modelled aerosol diameter distribution showed that more than 50% of the aerosols deposited in this zone is larger than 20 μm. Besides an anthropogenic source, the reaction of nitric or sulphuric acid with sea-salt aerosols, by which HCl (g) is formed, can be a second source of an excess of chloride in throughflow compared to sodium. The newly formed HCl can deposit as dry deposition on a vegetation, and not as dry bulk deposition. Chloride loss in the bulk deposition at the coastal sites was up to 35% in summertime. Chloride depletion also affects the calculation of potential acid deposition (PAD) in the coastal zone. Part of the NO 3- and excess SO 42- deposition should not be taken into account when calculating the PAD, because it is neutralized by the sea-salt. This effect decreases very soon with increasing distance to the sea. Implementing chloride depletion in calculating yearly PAD at 500 m from the coastline decreased the PAD with 26%. At 2000 m this decrease was 14%. However, in some cases PAD values on a fortnightly base were observed to decrease more than 50% after implementing chloride depletion.

  8. Using NASA EOS in the Arabian and Saharan Deserts to Examine Dust Particle Size and Spectral Signature of Aerosols

    NASA Astrophysics Data System (ADS)

    Brenton, J. C.; Keeton, T.; Barrick, B.; Cowart, K.; Cooksey, K.; Florence, V.; Herdy, C.; Luvall, J. C.; Vasquez, S.

    2012-12-01

    Exposure to high concentrations of airborne particulate matter can have adverse effects on the human respiratory system. Ground-based studies conducted in Iraq have revealed the presence of potential human pathogens in airborne dust. According to the Environmental Protection Agency (EPA), airborne particulate matter below 2.5μm (PM2.5) can cause long-term damage to the human respiratory system. Given the relatively high incidence of new-onset respiratory disorders experienced by US service members deployed to Iraq, this research offers a new glimpse into how satellite remote sensing can be applied to questions related to human health. NASA's Earth Observing System (EOS) can be used to determine spectral characteristics of dust particles, the depth of dust plumes, as well as dust particle sizes. Comparing dust particle size from the Sahara and Arabian Deserts gives insight into the composition and atmospheric transport characteristics of dust from each desert. With the use of NASA SeaWiFS DeepBlue Aerosol, dust particle sizes were estimated using Angström exponent. Brightness Temperature Difference (BTD) equation was used to determine the distribution of particle sizes, the area of the dust storm, and whether silicate minerals were present in the dust. The Moderate-resolution Imaging Spectroradiometer (MODIS) on Terra satellite was utilized in calculating BTD. Minimal research has been conducted on the spectral characteristics of airborne dust in the Arabian and Sahara Deserts. Mineral composition of a dust storm that occurred 17 April 2008 near Baghdad was determined using imaging spectrometer data from the Jet Propulsion Laboratory Spectral Library and EO-1 Hyperion data. Mineralogy of this dust storm was subsequently compared to that of a dust storm that occurred over the Bodélé Depression in the Sahara Desert on 7 June 2003.

  9. Aerosol retention during SGTR meltdown sequences: Experimental insights of the effect of size and shape of the breach

    SciTech Connect

    Herranz, L. E.; Tardaguila, R. D.; Lopez, C.

    2012-07-01

    This paper summarizes the major insights gained from aerosol retention capability of a tube bundle that simulates the break stage of the secondary side of a failed steam generator under dry SGTR conditions. This scenario is highly relevant in nuclear safety since it affects the potential retention of radioactive particles in case of meltdown sequences with a SGTR. An 8-test experimental campaign has been carried out, extending the current database on the decontamination capability of the steam generator. The effects of the breach features (shape and size) and the particle nature (SiO{sub 2} and TiO{sub 2}) on the collection efficiency have been explored. The results confirmed the strong effect of the physical nature even when tube breaks in a fish-mouth mode. Loose aggregates (i.e. TiO{sub 2}) would be trapped to a limited extent (less than 25%); while single- or few-aggregates (i.e. SiO{sub 2}) would undergo a quite effective removal (i.e. over 75%). For fish-mouth breaches and SiO{sub 2} particles, the breach size has been found to moderately affect retention efficiency. Furthermore, the breach shape does not seem to have any effect on the net collection efficiency within the break stage, no matter the particle type. However, individual tube measurements indicate notably different deposition patterns, although an effect of the facility geometry cannot be disregarded as a key player in this observation. (authors)

  10. Titan's aerosols. I - Laboratory investigations of shapes, size distributions, and aggregation of particles produced by UV photolysis of model Titan atmospheres

    NASA Technical Reports Server (NTRS)

    Scattergood, Thomas W.; Lau, Edmond Y.; Stone, Bradley M.

    1992-01-01

    Experiments in which C2H2, C2H4, and HCN were photolyzed separately and as a mixture in UV light have been conducted in order to ascertain the physical properties of model Titan atmosphere aerosols. Aerosols formed from photolysis of C2H4 were physically similar to those formed from C2H2; protolysis of HCN rapidly generated particles that did not grow to sizes greater than 0.09 microns. While the formation of particles from C4H2 was observed within minutes, formation was slowed by a factor of 4 when C2H2 and HCN were added.

  11. Size-partitioning of an urban aerosol to identify particle determinants involved in the proinflammatory response induced in airway epithelial cells

    PubMed Central

    Ramgolam, Kiran; Favez, Olivier; Cachier, Hélène; Gaudichet, Annie; Marano, Francelyne; Martinon, Laurent; Baeza-Squiban, Armelle

    2009-01-01

    Background The contribution of air particles in human cardio-respiratory diseases has been enlightened by several epidemiological studies. However the respective involvement of coarse, fine and ultrafine particles in health effects is still unclear. The aim of the present study is to determine which size fraction from a chemically characterized background aerosol has the most important short term biological effect and to decipher the determinants of such a behaviour. Results Ambient aerosols were collected at an urban background site in Paris using four 13-stage low pressure cascade impactors running in parallel (winter and summer 2005) in order to separate four size-classes (PM0.03–0.17 (defined here as ultrafine particles), PM0.17–1 (fine), PM1–2.5(intermediate) and PM2.5–10 (coarse)). Accordingly, their chemical composition and their pro-inflammatory potential on human airway epithelial cells were investigated. Considering isomass exposures (same particle concentrations for each size fractions) the pro-inflammatory response characterized by Granulocyte Macrophage-Colony Stimulating Factor (GM-CSF) release was found to decrease with aerosol size with no seasonal dependency. When cells were exposed to isovolume of particle suspensions in order to respect the particle proportions observed in ambient air, the GM-CSF release was maximal with the fine fraction. In presence of a recombinant endotoxin neutralizing protein, the GM-CSF release induced by particles is reduced for all size-fractions, with exception of the ultra-fine fraction which response is not modified. The different aerosol size-fractions were found to display important chemical differences related to the various contributing primary and secondary sources and aerosol age. The GM-CSF release was correlated to the organic component of the aerosols and especially its water soluble fraction. Finally, Cytochrome P450 1A1 activity that reflects PAH bioavailability varied as a function of the season

  12. 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

  13. Measurements of Aerosol Size Distributions in the Lower Troposphere over Northern Europe.

    DTIC Science & Technology

    1981-06-01

    in its passage from volume (or mass) versus particle size, as pointed out by outside the aircraft to the Royco scattering chamber. Whitby etal...symmetry and shape of the data relationship between 7 and A, This relationship will be cure is typical ot the analyzed data. Whitby (1978) more fully...discernible re;ationship between these parameters. the coarse particle mode, \\,,hich according to Whitby This is probably due to the sensitivity of the

  14. The Spatial Distribution and Size Evolution of Particles in Asian Outflow: The Significance of Primary and Secondary Aerosol during ACE-Asia and TRACE-P

    NASA Astrophysics Data System (ADS)

    Mĉnaughton, C. S.; Howell, S. G.; Clarke, A. D.; Blomquist, B.; Anderson, T.; Masonis, S. J.; Weber, R. J.; Eisele, F. L.; Mauldin, L.

    2002-12-01

    During March and April of 2001 NASA conducted the Transport and Chemical Evolution over the Pacific experiment (TRACE-P) and the NSF conducted the Asian Pacific Regional Aerosol Characterization Experiment (ACE-Asia). On March 18th NASA's P3-B aircraft intercepted an urban plume off the coast of China. From April 11th - 13th the NCAR/NSF C-130 aircraft sampled dust and urban aerosols associated with a passing cold front over a broad spatial extent. Using the University of Hawai`i thermally resolved Differential Mobility Analyzers (DMAs) and laser Optical Particle Counters (OPCs) aerosol size distributions were evaluated between 0.007μm and 20μm aboard both aircraft. These distributions show nucleation mode aerosols (Dp < 40nm) throughout the marine boundary layer (MBL) over several degrees of latitude and longitude during the April 11-13th event. Flights into the Yellow Sea and north and south of Kyushu Japan suggest that secondary aerosol formation occurred within the MBL most likely by gas to particle conversion shortly after sunrise. The presence of substantial concentrations of ammonium in the accumulation mode aerosol and partial neutralization of the nucleation mode aerosol suggest that the newly formed particles were created by a ternary rather than binary homogeneous nucleation mechanism involving H2SO4-H2O-NH3. Evidence for the evolution of the nucleation mode aerosol was observed throughout the day despite dry ambient aerosol surface area of 400 to 800 μm2/cm3. Estimates for the flux rate of sulfuric acid to the full size distribution were calculated at ~1.0\\times106 molecules/cm3/sec based on the growth rate of the nucleation mode. These calculated values are the same order of magnitude as production rates of H2SO4 observed at the same location during the TRACE-P campaign. This presentation highlights the observations from the ACE-Asia and TRACE-P field campaigns during the dust storm event and analyzes the survival of these recently formed particles

  15. Volcanic Signatures in Estimates of Stratospheric Aerosol Size, Distribution Width, Surface Area, and Volume Deduced from Global Satellite-Based Observations

    NASA Technical Reports Server (NTRS)

    Bauman, J. J.; Russell, P. B.

    2000-01-01

    Volcanic signatures in the stratospheric aerosol layer are revealed by two independent techniques which retrieve aerosol information from global satellite-based observations of particulate extinction. Both techniques combine the 4-wavelength Stratospheric Aerosol and Gas Experiment (SAGE) II extinction measurements (0.385 <= lambda <= 1.02 microns) with the 7.96 micron and 12.82 micron extinction measurements from the Cryogenic Limb Array Etalon Spectrometer (CLAES) instrument. The algorithms use the SAGE II/CLAES composite extinction spectra in month-latitude-altitude bins to retrieve values and uncertainties of particle effective radius R(sub eff), surface area S, volume V and size distribution width sigma(sub R). The first technique is a multi-wavelength Look-Up-Table (LUT) algorithm which retrieves values and uncertainties of R(sub eff) by comparing ratios of extinctions from SAGE II and CLAES (e.g., E(sub lambda)/E(sub 1.02) to pre-computed extinction ratios which are based on a range of unimodal lognormal size distributions. The pre-computed ratios are presented as a function of R(sub eff) for a given sigma(sub g); thus the comparisons establish the range of R(sub eff) consistent with the measured spectra for that sigma(sub g). The fact that no solutions are found for certain sigma(sub g) values provides information on the acceptable range of sigma(sub g), which is found to evolve in response to volcanic injections and removal periods. Analogous comparisons using absolute extinction spectra and error bars establish the range of S and V. The second technique is a Parameter Search Technique (PST) which estimates R(sub eff) and sigma(sub g) within a month-latitude-altitude bin by minimizing the chi-squared values obtained by comparing the SAGE II/CLAES extinction spectra and error bars with spectra calculated by varying the lognormal fitting parameters: R(sub eff), sigma(sub g), and the total number of particles N(sub 0). For both techniques, possible biases in

  16. Characteristics of aerosol and cloud particle size distributions in the tropical tropopause layer measured with optical particle counter and lidar

    NASA Astrophysics Data System (ADS)

    Iwasaki, S.; Maruyama, K.; Hayashi, M.; Ogino, S.-Y.; Ishimoto, H.; Tachibana, Y.; Shimizu, A.; Matsui, I.; Sugimoto, N.; Yamashita, K.; Saga, K.; Iwamoto, K.; Kamiakito, Y.; Chabangborn, A.; Thana, B.; Hashizume, M.; Koike, T.; Oki, T.

    2007-07-01

    An optical particle counter (OPC) is used in conjunction with lidar measurements to examine the characteristics of the particle size distribution in cirrus cloud in the tropical tropopause layer (TTL) over Thailand where the TTL is defined as the height at which temperature is lower than -75°C in this paper. Of 11 OPC launches, cirrus cloud was detected at 10-15 km high on 7 occasions, cirrus was detected in the TTL in 6 cases, and simultaneous OPC and lidar measurements were made on two occasions. Comparison of lidar and OPC measurements reveal that the cloud heights of cirrus in the TTL varies by several hundred meters over distances of tens kilometers; hence the height is not always horizontally uniform. The mode radii of particles constituting the clouds are estimated by lidar and OPC measurements to be less than approximately 10 μm. The regression lines of the particle size distribution with and without cirrus cloud exhibit similar features at equivalent radii of <0.8 μm. Enhancement in the integrated number concentration at radii greater than 0.8 μm indicates that liquid particles tend to be frozen at a radius of 0.8 μm, with cirrus clouds above 10 km exhibiting similar features. On the other hand, enhancement in the particle size distribution at radii greater than 0.9 μm and a peak at around 0.8 μm in the ratio of the standard deviation of count values to that of the Poisson distribution of the averaged count values are common features of cirrus clouds in the TTL, where the ratio shows the vertical homogeneity of the particle number. These typical features suggest that the transition from liquid, sulfuric acid aerosol, to ice is more observable in the TTL and the timing of freezing may vary with height in the TTL.

  17. Direct Deposition of Gas Phase Generated Aerosol Gold Nanoparticles into Biological Fluids - Corona Formation and Particle Size Shifts

    PubMed Central

    Svensson, Christian R.; Messing, Maria E.; Lundqvist, Martin; Schollin, Alexander; Deppert, Knut; Pagels, Joakim H.; Rissler, Jenny; Cedervall, Tommy

    2013-01-01

    An ongoing discussion whether traditional toxicological methods are sufficient to evaluate the risks associated with nanoparticle inhalation has led to the emergence of Air-Liquid interface toxicology. As a step in this process, this study explores the evolution of particle characteristics as they move from the airborne state into physiological solution. Airborne gold nanoparticles (AuNP) are generated using an evaporation-condensation technique. Spherical and agglomerate AuNPs are deposited into physiological solutions of increasing biological complexity. The AuNP size is characterized in air as mobility diameter and in liquid as hydrodynamic diameter. AuNP:Protein aggregation in physiological solutions is determined using dynamic light scattering, particle tracking analysis, and UV absorption spectroscopy. AuNPs deposited into homocysteine buffer form large gold-aggregates. Spherical AuNPs deposited in solutions of albumin were trapped at the Air-Liquid interface but was readily suspended in the solutions with a size close to that of the airborne particles, indicating that AuNP:Protein complex formation is promoted. Deposition into serum and lung fluid resulted in larger complexes, reflecting the formation of a more complex protein corona. UV absorption spectroscopy indicated no further aggregation of the AuNPs after deposition in solution. The corona of the deposited AuNPs shows differences compared to AuNPs generated in suspension. Deposition of AuNPs from the aerosol phase into biological fluids offers a method to study the protein corona formed, upon inhalation and deposition in the lungs in a more realistic way compared to particle liquid suspensions. This is important since the protein corona together with key particle properties (e.g. size, shape and surface reactivity) to a large extent may determine the nanoparticle effects and possible translocation to other organs. PMID:24086363

  18. Transient variation of aerosol size distribution in an underground subway station.

    PubMed

    Kwon, Soon-Bark; Namgung, Hyeong-Gyu; Jeong, Wootae; Park, Duckshin; Eom, Jin Ki

    2016-06-01

    As the number of people using rapid transit systems (subways) continues to rise in major cities worldwide, increasing attention has been given to the indoor air quality of underground stations. This study intended to observe the change of PM distribution by size in an underground station with PSDs installed located near the main road in downtown Seoul, as well as to examine causes for the changes. The results indicate that the PM suspended in the tunnel flowed into the platform area even in a subway station where the effect of train-induced wind is blocked by installed PSDs, as this flow occurred when the PSDs were opened. The results also indicate that coarse mode particles generated by mechanical friction in the tunnel, such as that between wheels and rail, also flowed into the platform area. The PM either settled or was re-suspended according to size and whether the ventilation in the platform area was in operation or if the platform floor had been washed. The ventilation system was more effective in removing PM of smaller sizes (fine particles) while the wash-out performed after train operations had stopped reduced the suspension of coarse mode particles the next morning. Despite installation of the completely sealed PSDs, inflow of coarse mode particles from the tunnel seems unavoidable, indicating the need for measures to decrease the PM generated there to lower subway user exposure since those particles cannot be reduced by mechanical ventilation alone. This research implicate that coarse PM containing heavy metals (generated from tunnel side) proliferated especially during rush hours, during which it is very important to control those PM in order to reduce subway user exposure to this hazardous PM.

  19. Fossil Fuel Combustion-Related Emissions Dominate Atmospheric Ammonia Sources during Severe Haze Episodes: Evidence from (15)N-Stable Isotope in Size-Resolved Aerosol Ammonium.

    PubMed

    Pan, Yuepeng; Tian, Shili; Liu, Dongwei; Fang, Yunting; Zhu, Xiaying; Zhang, Qiang; Zheng, Bo; Michalski, Greg; Wang, Yuesi

    2016-08-02

    The reduction of ammonia (NH3) emissions is urgently needed due to its role in aerosol nucleation and growth causing haze formation during its conversion into ammonium (NH4(+)). However, the relative contributions of individual NH3 sources are unclear, and debate remains over whether agricultural emissions dominate atmospheric NH3 in urban areas. Based on the chemical and isotopic measurements of size-resolved aerosols in urban Beijing, China, we find that the natural abundance of (15)N (expressed using δ(15)N values) of NH4(+) in fine particles varies with the development of haze episodes, ranging from -37.1‰ to -21.7‰ during clean/dusty days (relative humidity: ∼ 40%), to -13.1‰ to +5.8‰ during hazy days (relative humidity: 70-90%). After accounting for the isotope exchange between NH3 gas and aerosol NH4(+), the δ(15)N value of the initial NH3 during hazy days is found to be -14.5‰ to -1.6‰, which indicates fossil fuel-based emissions. These emissions contribute 90% of the total NH3 during hazy days in urban Beijing. This work demonstrates the analysis of δ(15)N values of aerosol NH4(+) to be a promising new tool for partitioning atmospheric NH3 sources, providing policy makers with insights into NH3 emissions and secondary aerosols for regulation in urban environments.

  20. Generation of a monodispersed aerosol

    NASA Technical Reports Server (NTRS)

    Schenck, H.; Mikasa, M.; Devicariis, R.

    1974-01-01

    The identity and laboratory test methods for the generation of a monodispersed aerosol are reported on, and are subjected to the following constraints and parameters; (1) size distribution; (2) specific gravity; (3) scattering properties; (4) costs; (5) production. The procedure called for the collection of information from the literature, commercial available products, and experts working in the field. The following topics were investigated: (1) aerosols; (2) air pollution -- analysis; (3) atomizers; (4) dispersion; (5) particles -- optics, size analysis; (6) smoke -- generators, density measurements; (7) sprays; (8) wind tunnels -- visualization.

  1. Size distribution of heavy metal aerosols in cooling and spray dryer system

    SciTech Connect

    Wey, M.Y.; Yang, J.T.; Peng, C.Y.; Chiang, B.C.

    1999-11-01

    The cooling process prior to treating flue gas and the spray dryer process that removes acid components in flue gas are believed to influence the mass and elemental size distributions of heavy metal in fly ash. The main objective of this study was to investigate the effects of operating parameters on the mass and elemental size distributions of heavy metals in fly ash produced from a fluidized bed incineration and a water cooling or spray dryer flue gas treatment system. The operating parameters investigated included (1) the controlling temperature in the gas cooling system; (2) the controlling temperature in the spray dryer system; (3) the addition of organic chlorides; and (4) the addition of inorganic chloride. The experimental results indicated that the water cooling process and spray dryer process increase the amount of coarse fly ash and increase the total concentration of metal in fly ash. The amounts of fine fly ash and the total concentration of metal in fine fly ash increase with decreasing temperature during the water cooling process. However, the amounts of fine fly ash and the total concentration of metal in fine fly ash decrease with decreasing temperature during the spray dryer process.

  2. COMMENTS ON "SIZE DISTRIBUTION OF ORGANONITRATES IN AMBIENT AEROSOL COLLECTED IN HOUSTON, TEXAS," AEROSOL SCIENCE AND TECHNOLOGY, 36:983-992 (2002)

    EPA Science Inventory

    A previous article in this journal reported the results of an FTIR analysis of the ambient aerosol collected during a file study in Houston, Texas during August and September of 2000. The emphasis of that article was on the organonitrates collected during the study. In the disc...

  3. Size-resolved aerosol chemical analysis of extreme haze pollution events during early 2013 in urban Beijing, China.

    PubMed

    Tian, Shili; Pan, Yuepeng; Liu, Zirui; Wen, Tianxue; Wang, Yuesi

    2014-08-30

    Using size-resolved filter sampling and chemical characterization, high concentrations of water-soluble ions, carbonaceous species and heavy metals were found in both fine (PM2.1) and coarse (PM2.1-9) particles in Beijing during haze events in early 2013. Even on clear days, average mass concentration of submicron particles (PM1.1) was several times higher than that previously measured in most of abroad urban areas. A high concentration of particulate matter on haze days weakens the incident solar radiation, which reduces the generation rate of secondary organic carbon in PM1.1. We show that the peak mass concentration of particles shifted from 0.43-0.65μm on clear days to 0.65-1.1μm on lightly polluted days and to 1.1-2.1μm on heavily polluted days. The peak shifts were also found for the following species: organic carbon, elemental carbon, NH4(+), SO4(2-), NO3(-), K, Cu, Zn, Cd and Pb. Our findings demonstrate that secondary inorganic aerosols (36%) and organic matter (26%) dominated the fine particle mass on heavily polluted days, while their contribution reduced to 29% and 18%, respectively, on clear days. Besides fine particles, anthropogenic chemical species also substantially accumulated in the coarse mode, which suggests that particles with aerodynamic diameter larger than 2.1μm cannot be neglected during severe haze events.

  4. In situ acidity and pH of size-fractionated aerosols during a recent smoke-haze episode in Southeast Asia.

    PubMed

    Behera, Sailesh N; Cheng, Jinping; Balasubramanian, Rajasekhar

    2015-10-01

    The characterization of aerosol acidity has received increased attention in recent years due to its influence on atmospheric visibility, climate change and human health. Distribution of water soluble inorganic (WSI) ions in 12 different size fractions of aerosols was investigated under two different atmospheric conditions (smoke-haze and non-haze periods) in 2012 using the Micro-Orifice Uniform Deposit Impactor (MOUDI) and nano-MOUDI for the first time in Singapore. To estimate the in situ acidity ([H(+)]Ins) and in situ aerosol pH (pHIS), the Aerosol Inorganic Model version-IV under deliquescent mode of airborne particles was used at prevailing ambient temperature and relative humidity. The study revealed an increase in the levels of airborne particulate matter (PM) mass and concentrations of WSI ions for all size fractions during the smoke-haze period, which was caused by the trans-boundary transport of biomass burning-impacted air masses from Indonesia. A bimodal distribution was observed for concentrations of SO4(2-), NO3(-), Cl(-), K(+) and Na(+), whereas concentrations of NH4(+), Ca(2+) and Mg(2+) showed a single mode distribution. The concentration of WSI ions in PM1.8 during the smoke-haze period increased by 3.8 (for SO4(2-)) to 10.5 (for K(+)) times more than those observed during the non-haze period. The pHIS were observed to be lower during the smoke-haze period than that during the non-haze period for all size fractions of PM, indicating that atmospheric aerosols were more acidic due to the influence of biomass burning emissions. The particles in the accumulation mode were more acidic than those in the coarse mode.

  5. Measurements of the Size-Resolved Chemical Composition of Marine Boundary Layer Aerosols in Asian Outflow During the ACE-Asia Campaign

    NASA Astrophysics Data System (ADS)

    Guazzotti, S. A.; Sodeman, D. A.; Moffet, R.; Prather, K. A.

    2003-12-01

    The size and chemical composition of individual particles were evaluated with high temporal resolution during the Asian Pacific Regional Aerosol Chemical Characterization Experiment (ACE-Asia) using a transportable aerosol time-of-flight mass spectrometer (ATOFMS) aboard the NOAA Research Vessel Ronald H. Brown. ATOFMS allows characterization of the aerodynamic diameter and chemical composition of individual particles from a polydisperse aerosol. This technique couples aerodynamic particle sizing with time-of-flight mass spectrometry in a single instrument, providing both positive and negative ion mass spectra for each detected particle which are employed to classify the particles into different classes using criteria based searches and a neural network algorithm, ART-2a. Size-resolved chemical characteristics of sampled particles under different synoptic meteorological patterns and at various locations and distances from continental influences are discussed in detail, with special focus given to the associations among different species and the variability in the degrees of aging, reaction, and/or mixing, which can alter the optical properties of these particles. Changes in the aerosol chemical characteristics due to heterogeneous reactions are evidenced in the mass spectra of detected particles by the presence and intensity of specific ion markers (e.g., sulfate, nitrate). The ability to differentiate between particles that have undergone heterogeneous reactions is relevant since these reactions affect several aerosol attributes, such as hygroscopic, optical, and radiative properties. Particularly, heterogeneous reactions/ nucleation on sea-salt and dust particles are discussed together with results of comparison efforts with some relevant laboratory and source characterization studies that allow determination of corresponding ion markers, relative ratios among species, and probable sources from a single particle perspective.

  6. Tritium discrimination using cluster size information from a DGEM detector

    NASA Astrophysics Data System (ADS)

    Surette, R. A.; Dubeau, J.

    2005-02-01

    Measurement of tritium-in-air concentrations is complicated by the presence of gamma radiation, 14C, and noble gas radionuclides. In most cases the signal from tritium, in conventional ion chamber-based monitors, is much smaller than that from equal concentrations of interfering radioactive gases. The lack of discrimination between tritium and other radioactive interferences frequently results in an overestimation of the tritium hazard. This report describes a method to effectively discriminate between tritium and other interfering airborne radioactive gases using ionization cluster size information from a double gas electron multiplier (DGEM) and a suitable readout array. The readout array consists of 121 pads (an 11×11 matrix of 4×4 mm pads on 6 mm centres) on a printed circuit board, each connected to a charge sensitive amplifier. The prototype-automated discriminating monitor typically indicated a spillover fraction, in the tritium channel, in the order of ±5% for binary mixtures of tritium and 14C, 85Kr, 133Xe or 41Ar. A custom-made dynamic cluster-fitting algorithm gives results in real-time with very good accuracy under extreme conditions.

  7. Aerosol Number-size Distributions and Hygroscopic Growth in the Marine Boundary Layer during ACE-Asia

    NASA Astrophysics Data System (ADS)

    Covert, D. S.; Coffman, D. J.; Bates, T. S.

    2001-12-01

    As part of the Aerosol Chemistry Experiment-Asia (ACE-Asia), measurements of the physical and hygroscopic properties of aerosol particles were made on the NOAA Research Vessel Ron Brown in the experiment's study area around southern Japan, the Sea of Japan and the Yellow Sea from 30 March through 19 April, 2001 (Day of Year 90 through 109). The number-size distribution from 3 nm to 10 um diameter was measured with a combination of differential mobility analyzers and aerodynamic particle sizers. The system was operated at 55% relative humidity (RH) for consistency with optical measurements and size dependent chemical sampling on the ship. A separate system consisting of three differential mobility analyzers and humidity conditioners measured the change in hydration of the accumulation mode particles from an initial condition of 55% RH to humidities of 20% and 90% RH. The result is a distribution of hygroscopic growth factors at the end RH relative to the initial humidity. The size distributions varied widely depending on the location of the ship, the source of the air mass and the local meteorological conditions. The dominant features included ultrafine particles (less than 20 nm), soil dust particulate mass (greater than 2 um) and Aitken, accumulation mode number and mass (40 to 600 nm). The results are limited to case studies rather than any statistical or time-space average due to the limited data base and the few sources and air mass types encountered in the 21 day period. The results have been analyzed and categorized according to specific air mass trajectories and chemical analysis and are considered representative of those air masses at the marine boundary layer level. Soil dust dominated distributions were observed on days 101 through 103 with volume concentrations of 50 to 100 um3/cm3 and a volume mean diameter of 3 um. High concentrations of ultrafine particles were observed on the later two of these days from early morning through mid-afternoon in spite

  8. Measured and modelled cloud condensation nuclei (CCN) concentration in São Paulo, Brazil: the importance of aerosol size-resolved chemical composition on CCNhack concentration prediction

    NASA Astrophysics Data System (ADS)

    Almeida, G. P.; Brito, J.; Morales, C. A.; Andrade, M. F.; Artaxo, P.

    2014-07-01

    Measurements of cloud condensation nuclei (CCN), aerosol size distribution and non-refractory chemical composition were performed from 16 to 31 October 2012 in the São Paulo Metropolitan Area (SPMA), Brazil. CCN measurements were performed at 0.23, 0.45, 0.68, 0.90 and 1.13% water supersaturation and were subsequently compared with the Köhler theory, considering the chemical composition. Real-time chemical composition has been obtained by deploying, for the first time in the SPMA, an aerosol chemical ionization monitor (ACSM). CCN closure analyses were performed considering internal mixtures. Average aerosol composition during the studied period yielded (arithmetic mean~± standard deviation) 4.81 ± 3.05, 3.26 ± 2.10, 0.30 ± 0.27, 0.52 ± 0.32, 0.37 ± 0.21 and 0.04 ± 0.04 μg m-3 for organics, BC, NH4, SO4, NO3 and Cl, respectively. Particle number concentration was 12 813 ± 5350 cm-3, with a dominant nucleation mode. CCN concentrations were on average 1090 ± 328 and 3570 ± 1695 cm-3 at SS = 0.23% and SS = 1.13%, respectively. Results show an increase in aerosol hygroscopicity in the afternoon as a result of aerosol photochemical processing, leading to an enhancement of both organic and inorganic secondary aerosols in the atmosphere, as well as an increase in aerosol average diameter. Considering the bulk composition alone, observed CCN concentrations were substantially overpredicted when compared with the Köhler theory (44.1 ± 47.9% at 0.23% supersaturation and 91.4 ± 40.3% at 1.13% supersaturation). Overall, the impact of composition on the calculated CCN concentration (NCCN) decreases with decreasing supersaturation, partially because using bulk composition introduces less bias for large diameters and lower critical supersaturations, defined as the supersaturation at which the cloud droplet activation will take place. Results suggest that the consideration of only inorganic fraction improves the calculated NCCN. Introducing a size-dependent chemical

  9. Free and combined amino acids in size-segregated atmospheric aerosol samples

    NASA Astrophysics Data System (ADS)

    Di Filippo, Patrizia; Pomata, Donatella; Riccardi, Carmela; Buiarelli, Francesca; Gallo, Valentina; Quaranta, Alessandro

    2014-12-01

    Concentrations of free and combined amino acids in an urban atmosphere and their distributions in size-segregated particles were investigated in the cold and warm seasons. In particular this article provides the first investigation of protein bioaerosol concentrations in ultrafine fraction (PM0.1) of particulate matter. In addition the present work provides amino acid and total proteinaceous material concentrations in NIST SRM 1649b, useful as reference values. The reference material was also used to build matrix matched calibration curves. Free amino acid total content in winter and summer PM0.1 was respectively 48.0 and 94.4 ng m-3, representing about 0.7 and 7.4% by weight of urban particulate matter in the two seasons. Total airborne protein and peptide concentrations in the same ultrafine fractions were 93.6 and 449.9 ng m-3 respectively in winter and in summer, representing 7.5 and 35.4% w/w of PM0.1, and demonstrating an exceptionally high percentage in summer ultrafine fraction. The significant potential adverse health effects of ultrafine particulate matter include allergies mainly caused by protein particles and we assumed that in summer 162 ng h-1 of proteinaceous material, by means of ultrafine particles, can penetrate from the lungs into the bloodstream.

  10. Experimental determination of the steady-state charging probabilities and particle size conservation in non-radioactive and radioactive bipolar aerosol chargers in the size range of 5-40 nm

    NASA Astrophysics Data System (ADS)

    Kallinger, Peter; Szymanski, Wladyslaw W.

    2015-04-01

    Three bipolar aerosol chargers, an AC-corona (Electrical Ionizer 1090, MSP Corp.), a soft X-ray (Advanced Aerosol Neutralizer 3087, TSI Inc.), and an α-radiation-based 241Am charger (tapcon & analysesysteme), were investigated on their charging performance of airborne nanoparticles. The charging probabilities for negatively and positively charged particles and the particle size conservation were measured in the diameter range of 5-40 nm using sucrose nanoparticles. Chargers were operated under various flow conditions in the range of 0.6-5.0 liters per minute. For particular experimental conditions, some deviations from the chosen theoretical model were found for all chargers. For very small particle sizes, the AC-corona charger showed particle losses at low flow rates and did not reach steady-state charge equilibrium at high flow rates. However, for all chargers, operating conditions were identified where the bipolar charge equilibrium was achieved. Practically, excellent particle size conservation was found for all three chargers.

  11. A laboratory study of the performance of the handheld diffusion size classifier (DiSCmini) for various aerosols in the 15-400 nm range.

    PubMed

    Bau, S; Zimmermann, B; Payet, R; Witschger, O

    2015-02-01

    In addition to chemical composition, particle concentration and size are among the main parameters used to characterize exposure to airborne ultrafine or nanoparticles. To assess occupational inhalation exposure, real-time instruments are recommended in recent strategies published. Among portable devices for personal exposure assessment in the workplace, DiSCmini (Matter Aerosol AG, Switzerland) has been identified as a potential candidate with its capacity to measure the airborne nanoparticle concentration and average particle size with good time-resolution. Monodisperse and polydisperse test nanoaerosols of varying compositions and morphologies were produced in the laboratory using the CAIMAN facility. These aerosols covered a range of particle sizes between 15 and 400 nm and number concentrations from 700 to 840,000 cm(-3). The aerosols were used to investigate the behavior of DiSCmini, comparing experimental data to reference data. In spite of a slight tendency to underestimate particle size, all particle diameters, number concentrations and surface area concentrations measured were in the same order of magnitude as reference data. Furthermore, no significant effect due to particle composition or morphology was noted.

  12. Aerosol size distribution and new particle formation events in the suburb of Xi'an, northwest China

    NASA Astrophysics Data System (ADS)

    Peng, Yan; Liu, Xiaodong; Dai, Jin; Wang, Zhao; Dong, Zipeng; Dong, Yan; Chen, Chuang; Li, Xingmin; Zhao, Na; Fan, Chao

    2017-03-01

    Particle number concentration and size distribution are important for better understanding the characteristics of aerosols. However, their measurements are scarce in western China. Based on the first measurement of particle number size distribution (10-487 nm) in the suburb of Xi'an, northwest China from November 2013 to December 2014, the seasonal, monthly and diurnal average particle number concentrations were investigated, and the characteristics of new particle formation (NPF) events and their dependencies on meteorological parameters also discussed. The results showed that the annual average particle number concentrations in the nucleation (NNUC), Aitken (NAIT), and Accumulation (NACC) size ranges were 960 cm-3, 4457 cm-3, 3548 cm-3, respectively. The mean total particle number concentration (NTOT) was 8965 cm-3 and largely dominated by particles in Aitken mode. The number concentration was dominated by particles around 67.3 nm in spring, summer and fall, while about 89.8 nm in winter. The percentage of the ultrafine size range (UFP, particles of diameter below 100 nm) to total particle number concentration was 63.2%, 69.6%, 62.2% and 58.1% in four seasons. The diurnal variation of the nucleation mode particles was mainly influenced by NPF events in summer, while by both traffic densities and NPF events in spring, fall and winter. The diurnal variation of the number concentration of Aitken mode particles correlated with the traffic emission in spring, fall and winter, while in summer it more correlated with contribution of the growth of the nucleation mode particles. The burst of nucleation mode particles typically started in the daytime (08:15-16:05, LST). The growth rates of nucleated particles ranged from 2.8 to 10.7 nm h-1 with an average of 5.0 ± 1.9 nm h-1. Among observed 66 NPF events from 347 effective measurement days, 85 percent of their air masses came from north or northwest China, resulting in a low concentration of pre-existing particles, and

  13. A detailed investigation of ambient aerosol composition and size distribution in an urban atmosphere.

    PubMed

    Kuzu, S Levent; Saral, Arslan; Demir, Selami; Summak, Gülsüm; Demir, Göksel

    2013-04-01

    This research was executed between March 2009 and March 2010 to monitor particulate matter size distribution and its composition in Istanbul. Particulate matter composition was determined using ion chromatography and inductively coupled plasma optical emission spectrometry. The sampling point is adjacent to a crowded road and the Bosporus Strait. Two prevailing particulate modes are found throughout PM10 by sampling with a nine-stage low-volume cascade impactor. First mode in the fine mode is found to be between 0.43 and 0.65 μm, whereas the other peak was observed between 3.3 and 4.7 μm, referring to the coarse mode. The mean PM10 concentration was determined as 41.2 μg/m(3), with a standard deviation of 16.92 μg/m(3). PM0.43 had the highest mean concentration value of 10.67 μg/m(3), making up nearly one fourth of the total PM10 mass. For determining the effect of traffic on particulate matter (PM) composition and distribution, four different sampling cycles were applied: entire day, nighttime, rush hour, and rush hour at weekdays. SO4(-2) and organic carbon/elemental carbon proportions are found to be lower in night samples, representing a decrease in traffic. The long-range transports of dust storms were observed during the sampling periods. Their effects were determined analytically and their route models were run by the HYSPLIT model and validated through satellite photographs taken by the NASA Earth Observatory.

  14. Method for estimation of refractive index and size distribution of aerosol using direct and diffuse solar irradiance and aureole by means of simulated annealing

    NASA Astrophysics Data System (ADS)

    Arai, Kohei; Liang, XingMing

    2003-12-01

    An estimation method for refractive index and size distribution of aerosols using measurements of direct and diffuse solar irradiance as well as the solar aureole by means of a modified simulated annealing is proposed. The proposed method is based on simulated annealing modified to acceralate a learning process by using a gradually decreasing oscillation function of temperature of annealing. By a using Gauss Seidel based atmospheric code, simulation data of direct and diffuse solar irradiance are generated together with estimated aureole measurements by means of an empirical method derived from experimental data. A comparison between the existing method proposed by P Romanov et.al. based on a linear inversion method and the proposed method is made. The results show double improvement of the estimation accuracy for both the aerosol size distribution and refractive index.

  15. Size distribution of carbonaceous aerosols at a high-altitude site on the central Tibetan Plateau (Nam Co Station, 4730 m a.s.l.)

    NASA Astrophysics Data System (ADS)

    Wan, Xin; Kang, Shichang; Wang, Yuesi; Xin, Jinyuan; Liu, Bin; Guo, Yuhong; Wen, Tianxue; Zhang, Guoshuai; Cong, Zhiyuan

    2015-02-01

    The chemical composition and size distribution characteristics of atmospheric aerosols have important effects on the environment, human health and climate change. In this paper, we study the size distribution of carbonaceous aerosols at the remote and pristine site, Nam Co Monitoring and Research Station for Multisphere Interactions, in the inland Tibetan Plateau (TP) based on collected size-segregated aerosols during 2012. The samples were quantified using the thermal/optical (TOR) method. The overall average concentrations of OC and EC in TSP, PM9.0, PM2.1, and PM1.0 were 4.61 μg m- 3 and 0.19 μg m- 3, 4.52 μg m- 3 and 0.18 μg m- 3, 2.72 μg m- 3 and 0.11 μg m- 3, and 2.11 μg m- 3 and 0.09 μg m- 3, respectively. Generally, the highest concentration of OC and EC in different aerosol size occurred during winter. The low level of EC indicated that direct anthropogenic disturbances in the interior of the TP still remain insignificant. The size distributions of OC and EC concentrations presented bimodal variations. In winter, pre-monsoon, monsoon, and post-monsoon seasons, the peaks for OC were in droplet mode (0.43-0.65 μm) and coarse mode (4.7-5.8 μm); while in the monsoon period, the coarse mode shifted to a smaller size bin (3.3-4.7 μm). The coarse mode may be due to dust particles while the droplet mode may be due to the growth process of particles. For EC, the peaks variations in coarse mode were as same as OC, while the other peaks were complicated: the peaks during winter, pre-monsoon, and monsoon seasons exhibited in droplet mode (1.1-2.1 μm, 0.65-1.1 μm, and 0.43-0.65 μm, respectively), and in post-monsoon period, the peak located in condensation mode. The highest peak concentrations for OC and EC occurred in winter and the pre-monsoon period, while the lowest peak values in the monsoon and post-monsoon periods, respectively. The size distribution variations may be caused by deposition, gas/particles exchange, hygroscopic growth, external mixing

  16. Measurement of the atmospheric aerosol particle size distribution in a highly polluted mega-city in Southeast Asia (Dhaka-Bangladesh)

    NASA Astrophysics Data System (ADS)

    Salam, Abdus; Mamoon, Hassan Al; Ullah, Md. Basir; Ullah, Shah M.

    2012-11-01

    Aerosol particle size distribution was measured with an aerodynamic particle sizer (APS) spectrometer continuously from January 21 to April 24, 2006 in Dhaka, Bangladesh. Particles number, surface and mass distributions data were stored automatically with Aerosol Instrument Manager (AIM) software on average every half an hour in a computer attached to the APS. The grand total average of number, surface and mass concentrations were 8.2 × 103 ± 7.8 × 103 particles cm-3, 13.3 × 103 ± 11.8 × 103 μm2 cm-3 and 3.04 ± 2.10 mg m-3, respectively. Fine particles with diameter smaller than 1.0 μm aerodynamic diameter (AD) dominated the number concentration, accounted for 91.7% of the total particles indicating vehicular emissions were dominating in Dhaka air either from fossil fuel burning or compressed natural gas (CNGs). The surface and mass concentrations between 0.5 and 1.0 μm AD were about 56.0% and 26.4% of the total particles, respectively. Remarkable seasonal differences were observed between winter and pre-monsoon seasons with the highest monthly average in January and the lowest in April. Aerosol particles in winter were 3.79 times higher for number, 3.15 times for surface and 2.18 times for mass distributions than during the pre-monsoon season. Weekends had lower concentrations than weekdays due to less vehicular traffic in the streets. Aerosol particles concentrations were about 15.0% (ranging from 9.4% to 17.3%) higher during traffic peak hours (6:00am-8:00pm) than off hours (8:00pm-6:00am). These are the first aerosol size distribution measurements with respect to number, surface and mass concentrations in real time at Dhaka, Bangladesh.

  17. AEROSOL AND GAS MEASUREMENT

    EPA Science Inventory

    Measurements provide fundamental information for evaluating and managing the impact of aerosols on air quality. Specific measurements of aerosol concentration and their physical and chemical properties are required by different users to meet different user-community needs. Befo...

  18. Measured In Situ Atmospheric Ambient Aerosol Size-Distributions, Particle Concentrations, and Turbulence Data for RSA TA-6 Test Range, Redstone Arsenal, AL, April-May 2015

    DTIC Science & Technology

    2015-09-01

    Concentrations, and Turbulence Data for RSA TA-6 Test Range, Redstone Arsenal , AL, April–May 2015 by Kristan Gurton, Stephanie Cunningham, and...Aerosol Size-Distributions, Particle Concentrations, and Turbulence Data for RSA TA-6 Test Range, Redstone Arsenal , AL, April–May 2015 by Kristan...Redstone Arsenal , AL Approved for public release; distribution unlimited. ii REPORT DOCUMENTATION PAGE Form Approved OMB No. 0704-0188

  19. 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.

  20. 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.

  1. 40 CFR Table F-4 to Subpart F of... - Estimated Mass Concentration Measurement of PM2.5 for Idealized Coarse Aerosol Size Distribution

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 5 2011-07-01 2011-07-01 false Estimated Mass Concentration Measurement of PM2.5 for Idealized Coarse Aerosol Size Distribution F Table F-4 to Subpart F of Part 53... Equivalent Methods for PM2.5 Pt. 53, Subpt. F, Table F-4 Table F-4 to Subpart F of Part 53—Estimated...

  2. 40 CFR Table F-5 to Subpart F of... - Estimated Mass Concentration Measurement of PM2.5 for Idealized “Typical” Coarse Aerosol Size...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 5 2010-07-01 2010-07-01 false Estimated Mass Concentration Measurement of PM2.5 for Idealized âTypicalâ Coarse Aerosol Size Distribution F Table F-5 to Subpart F of Part... of Class II Equivalent Methods for PM2.5 Pt. 53, Subpt. F, Table F-5 Table F-5 to Subpart F of...

  3. 40 CFR Table F-6 to Subpart F of... - Estimated Mass Concentration Measurement of PM2.5 for Idealized Fine Aerosol Size Distribution

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 5 2010-07-01 2010-07-01 false Estimated Mass Concentration Measurement of PM2.5 for Idealized Fine Aerosol Size Distribution F Table F-6 to Subpart F of Part 53... Equivalent Methods for PM2.5 Pt. 53, Subpt. F, Table F-6 Table F-6 to Subpart F of Part 53—Estimated...

  4. 40 CFR Table F-4 to Subpart F of... - Estimated Mass Concentration Measurement of PM2.5 for Idealized Coarse Aerosol Size Distribution

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 5 2010-07-01 2010-07-01 false Estimated Mass Concentration Measurement of PM2.5 for Idealized Coarse Aerosol Size Distribution F Table F-4 to Subpart F of Part 53... Equivalent Methods for PM2.5 Pt. 53, Subpt. F, Table F-4 Table F-4 to Subpart F of Part 53—Estimated...

  5. 40 CFR Table F-5 to Subpart F of... - Estimated Mass Concentration Measurement of PM2.5 for Idealized “Typical” Coarse Aerosol Size...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 5 2011-07-01 2011-07-01 false Estimated Mass Concentration Measurement of PM2.5 for Idealized âTypicalâ Coarse Aerosol Size Distribution F Table F-5 to Subpart F of Part... of Class II Equivalent Methods for PM2.5 Pt. 53, Subpt. F, Table F-5 Table F-5 to Subpart F of...

  6. 40 CFR Table F-6 to Subpart F of... - Estimated Mass Concentration Measurement of PM2.5 for Idealized Fine Aerosol Size Distribution

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 5 2011-07-01 2011-07-01 false Estimated Mass Concentration Measurement of PM2.5 for Idealized Fine Aerosol Size Distribution F Table F-6 to Subpart F of Part 53... Equivalent Methods for PM2.5 Pt. 53, Subpt. F, Table F-6 Table F-6 to Subpart F of Part 53—Estimated...

  7. Polarimetric remote sensing in oxygen A and B bands: sensitivity study and information content analysis for vertical profile of aerosols

    NASA Astrophysics Data System (ADS)

    Ding, Shouguo; Wang, Jun; Xu, Xiaoguang

    2016-05-01

    Theoretical analysis is conducted to reveal the information content of aerosol vertical profile in space-borne measurements of the backscattered radiance and degree of linear polarization (DOLP) in oxygen (O2) A and B bands. Assuming a quasi-Gaussian shape for aerosol vertical profile characterized by peak height H and half width γ (at half maximum), the Unified Linearized Vector Radiative Transfer Model (UNL-VRTM) is used to simulate the Stokes four-vector elements of upwelling radiation at the top of atmosphere (TOA) and their Jacobians with respect to H and γ. Calculations for different aerosol types and different combinations of H and γ values show that the wide range of gas absorption optical depth in O2 A and B band enables the sensitivity of backscattered DOLP and radiance at TOA to the aerosol layer at different altitudes. Quantitatively, DOLP in O2 A and B bands is found to be more sensitive to H and γ than radiance, especially over the bright surfaces (with large visible reflectance). In many O2 absorption wavelengths, the degree of freedom of signal (DFS) for retrieving H (or γ) generally increases with H (and γ) and can be close to unity in many cases, assuming that the composite uncertainty from surface and aerosol scattering properties as well as measurements is less than 5 %. Further analysis demonstrates that DFS needed for simultaneous retrieval of H and γ can be obtained from a combined use of DOLP measurements at ˜ 10-100 O2 A and B absorption wavelengths (or channels), depending on the specific values of H. The higher the aerosol layer, the fewer number of channels for DOLP measurements in O2 A and B bands are needed for characterizing H and γ. Future hyperspectral measurements of DOLP in O2 A and B bands are needed to continue studying their potential and their combination with radiance and DOLP in atmospheric window channels for retrieving the vertical profiles of aerosols, especially highly scattering aerosols, over land.

  8. Observation of atmospheric aerosols at Mt. Hua and Mt. Tai in Central and East China during spring 2009 - Part 2: Impact of dust storm on organic aerosol composition and size distribution

    NASA Astrophysics Data System (ADS)

    Wang, G. H.; Li, J. J.; Cheng, C. L.; Zhou, B. H.; Xie, M. J.; Hu, S. Y.; Meng, J. J.; Sun, T.; Ren, Y. Q.; Cao, J. J.; Liu, S. X.; Zhang, T.; Zhao, Z. Z.

    2011-12-01

    PM10 and size-resolved particles (9-stage) were simultaneously collected at Mt. Hua and Mt. Tai in Central and East China during the spring of 2009 including a massive dust storm occurring on April 24th (named as DS II), and determined for organic compounds to investigate the impact of dust storm on organic aerosols. High molecular weight (HMW) n-alkanes, fatty acids, and fatty alcohols and trehalose sharply increased and almost entirely stayed in coarse particles when dust storm was present, suggesting that high level of organic aerosols in the mountain atmospheres during the event originated from biogenic sources in the Gobi desert. However, most anthropogenic aerosols (e.g., PAHs, aromatic acids and dicarboyxlic acids) during the event significantly decreased due to a dilution effect, indicating that anthropogenic aerosols in the mountain air during the nonevent period are largely derived from local/regional sources rather than from long-range transport. Our results indicate that trehalose can be taken as a new tracer for dust emissions from desert regions since trehalose was negligible in the nonevent but abundant in the event. Molecular compositions of organic aerosols in the mountain samples further demonstrate that domestic coal burning is still the major source of PAHs in China. n-Alkanes and fatty acids showed a bimodal size distribution during the nonevent with a major peak in fine mode (<2.1 μm) and a small peak in coarse mode (>2.1 μm). The coarse mode significantly increased and even dominated over the whole size range when dust was present. Glucose and trehalose were also dominant in the coarse mode especially in the DS II time. PAHs and levoglucosan concentrated in fine particles with no significant changes in size distribution when dust storm occurred. However, phthalic and succinic acids showed bimodal size distribution pattern with an increase in coarse mode during the event, because both are formed via a gas phase oxidation and a subsequent

  9. Observation of atmospheric aerosols at Mt. Hua and Mt. Tai in central and east China during spring 2009 - Part 2: Impact of dust storm on organic aerosol composition and size distribution

    NASA Astrophysics Data System (ADS)

    Wang, G. H.; Li, J. J.; Cheng, C. L.; Zhou, B. H.; Xie, M. J.; Hu, S. Y.; Meng, J. J.; Sun, T.; Ren, Y. Q.; Cao, J. J.; Liu, S. X.; Zhang, T.; Zhao, Z. Z.

    2012-05-01

    PM10 and size-resolved particles (9-stage) were simultaneously collected at Mt. Hua and Mt. Tai in central and east China during the spring of 2009 including a massive dust storm occurring on 24 April (named as DS II), and determined for organic compounds to investigate the impact of dust storm on organic aerosols. High molecular weight (HMW) n-alkanes, fatty acids, and fatty alcohols and trehalose sharply increased and almost entirely stayed in coarse particles when dust storm was present, suggesting that high level of organic aerosols in the mountain atmospheres during the event largely originated from Gobi desert plants. However, most anthropogenic aerosols (e.g. PAHs, and aromatic and dicarboxylic acids) during the event significantly decreased due to a dilution effect, indicating that anthropogenic aerosols in the mountain atmospheres during the nonevent period largely originated from local/regional sources rather than from long-range transport. Trehalose, a metabolism product enriched in biota in dry conditions, was 62 ± 78 and 421 ± 181 ng m-3 at Mt. Hua and Mt. Tai during DS II, 10-30 times higher than that in the nonevent time, indicating that trehalose may be a tracer for dust emissions from Gobi desert regions. Molecular compositions of organic aerosols in the mountain samples demonstrate that domestic coal burning is still the major source of PAHs in China. n-Alkanes and fatty acids showed a bimodal size distribution during the nonevent with a major peak in fine mode (<2.1 μm) and a small peak in coarse mode (>2.1 μm). The coarse mode significantly increased and even dominated over the whole size range when dust was present. Glucose and trehalose were also dominant in the coarse mode especially in the DS II time. PAHs and levoglucosan concentrated in fine particles with no significant changes in size distribution when dust storm occurred. However, phthalic and succinic acids showed bimodal size distribution pattern with an increase in coarse mode

  10. Cloud Droplet Size and Liquid Water Path Retrievals From Zenith Radiance Measurements: Examples From the Atmospheric Radiation Measurement Program and the Aerosol Robotic Network

    NASA Technical Reports Server (NTRS)

    Chiu, J. C.; Marshak, A.; Huang, C.-H.; Varnai, T.; Hogan, R. J.; Giles, D. M.; Holben, B. N.; Knyazikhin, Y.; O'Connor, E. J.; Wiscombe, W. J.

    2012-01-01

    The ground-based Atmospheric Radiation Measurement Program (ARM) and NASA Aerosol Robotic Network (AERONET) routinely monitor clouds using zenith radiances at visible and near-infrared wavelengths. Using the transmittance calculated from such measurements, we have developed a new retrieval method for cloud effective droplet size and conducted extensive tests for non-precipitating liquid water clouds. The underlying principle is to combine a water-absorbing wavelength (i.e. 1640 nm) with a nonwater-absorbing wavelength for acquiring information on cloud droplet size and optical depth. For simulated stratocumulus clouds with liquid water path less than 300 g/sq m and horizontal resolution of 201m, the retrieval method underestimates the mean effective radius by 0.8 m, with a root-mean-squared error of 1.7 m and a relative deviation of 13 %. For actual observations with a liquid water path less than 450 gm.2 at the ARM Oklahoma site during 2007-2008, our 1.5 min-averaged retrievals are generally larger by around 1 m than those from combined ground-based cloud radar and microwave radiometer at a 5min temporal resolution. We also compared our retrievals to those from combined shortwave flux and microwave observations for relatively homogeneous clouds, showing that the bias between these two retrieval sets is negligible, but the error of 2.6 m and the relative deviation of 22% are larger than those found in our simulation case. Finally, the transmittance-based cloud effective droplet radii agree to better than 11% with satellite observations and have a negative bias of 1 m. Overall, the retrieval method provides reasonable cloud effective radius estimates, which can enhance the cloud products of both ARM and AERONET.

  11. Cloud droplet size and liquid water path retrievals from zenith radiance measurements: examples from the Atmospheric Radiation Measurement Program and the Aerosol Robotic Network

    NASA Astrophysics Data System (ADS)

    Chiu, J. C.; Marshak, A.; Huang, C.-H.; Várnai, T.; Hogan, R. J.; Giles, D. M.; Holben, B. N.; O'Connor, E. J.; Knyazikhin, Y.; Wiscombe, W. J.

    2012-11-01

    The ground-based Atmospheric Radiation Measurement Program (ARM) and NASA Aerosol Robotic Network (AERONET) routinely monitor clouds using zenith radiances at visible and near-infrared wavelengths. Using the transmittance calculated from such measurements, we have developed a new retrieval method for cloud effective droplet size and conducted extensive tests for non-precipitating liquid water clouds. The underlying principle is to combine a liquid-water-absorbing wavelength (i.e., 1640 nm) with a non-water-absorbing wavelength for acquiring information on cloud droplet size and optical depth. For simulated stratocumulus clouds with liquid water path less than 300 g m-2 and horizontal resolution of 201 m, the retrieval method underestimates the mean effective radius by 0.8 μm, with a root-mean-squared error of 1.7 μm and a relative deviation of 13%. For actual observations with a liquid water path less than 450 g m-2 at the ARM Oklahoma site during 2007-2008, our 1.5-min-averaged retrievals are generally larger by around 1 μm than those from combined ground-based cloud radar and microwave radiometer at a 5-min temporal resolution. We also compared our retrievals to those from combined shortwave flux and microwave observations for relatively homogeneous clouds, showing that the bias between these two retrieval sets is negligible, but the error of 2.6 μm and the relative deviation of 22% are larger than those found in our simulation case. Finally, the transmittance-based cloud effective droplet radii agree to better than 11% with satellite observations and have a negative bias of 1 μm. Overall, the retrieval method provides reasonable cloud effective radius estimates, which can enhance the cloud products of both ARM and AERONET.

  12. Cloud droplet size and liquid water path retrievals from zenith radiance measurements: examples from the Atmospheric Radiation Measurement Program and the Aerosol Robotic Network

    NASA Astrophysics Data System (ADS)

    Chiu, J. C.; Marshak, A.; Huang, C.-H.; Várnai, T.; Hogan, R. J.; Giles, D. M.; Holben, B. N.; O'Connor, E. J.; Knyazikhin, Y.; Wiscombe, W. J.

    2012-08-01

    The ground-based Atmospheric Radiation Measurement Program (ARM) and NASA Aerosol Robotic Network (AERONET) routinely monitor clouds using zenith radiances at visible and near-infrared wavelengths. Using the transmittance calculated from such measurements, we have developed a new retrieval method for cloud effective droplet size and conducted extensive tests for non-precipitating liquid water clouds. The underlying principle is to combine a water-absorbing wavelength (i.e. 1640 nm) with a non-water-absorbing wavelength for acquiring information on cloud droplet size and optical depth. For simulated stratocumulus clouds with liquid water path less than 300 g m-2 and horizontal resolution of 201 m, the retrieval method underestimates the mean effective radius by 0.8 μm, with a root-mean-squared error of 1.7 μm and a relative deviation of 13%. For actual observations with a liquid water path less than 450 g m-2 at the ARM Oklahoma site during 2007-2008, our 1.5 min-averaged retrievals are generally larger by around 1 μm than those from combined ground-based cloud radar and microwave radiometer at a 5 min temporal resolution. We also compared our retrievals to those from combined shortwave flux and microwave observations for relatively homogeneous clouds, showing that the bias between these two retrieval sets is negligible, but the error of 2.6 μm and the relative deviation of 22% are larger than those found in our simulation case. Finally, the transmittance-based cloud effective droplet radii agree to better than 11% with satellite observations and have a negative bias of 1 μm. Overall, the retrieval method provides reasonable cloud effective radius estimates, which can enhance the cloud products of both ARM and AERONET.

  13. 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.

  14. Improved solid aerosol generator

    DOEpatents

    Prescott, D.S.; Schober, R.K.; Beller, J.

    1988-07-19

    An improved solid aerosol generator used to produce a gas borne stream of dry, solid particles of predetermined size and concentration. The improved solid aerosol generator nebulizes a feed solution of known concentration with a flow of preheated gas and dries the resultant wet heated aerosol in a grounded, conical heating chamber, achieving high recovery and flow rates. 2 figs.

  15. Solid aerosol generator

    DOEpatents

    Prescott, Donald S.; Schober, Robert K.; Beller, John

    1992-01-01

    An improved solid aerosol generator used to produce a gas borne stream of dry, solid particles of predetermined size and concentration. The improved solid aerosol generator nebulizes a feed solution of known concentration with a flow of preheated gas and dries the resultant wet heated aerosol in a grounded, conical heating chamber, achieving high recovery and flow rates.

  16. Solid aerosol generator

    DOEpatents

    Prescott, D.S.; Schober, R.K.; Beller, J.

    1992-03-17

    An improved solid aerosol generator used to produce a gas borne stream of dry, solid particles of predetermined size and concentration is disclosed. The improved solid aerosol generator nebulizes a feed solution of known concentration with a flow of preheated gas and dries the resultant wet heated aerosol in a grounded, conical heating chamber, achieving high recovery and flow rates. 2 figs.

  17. Climatology of Aerosol Optical Properties in Southern Africa

    NASA Technical Reports Server (NTRS)

    Queface, Antonio J.; Piketh, Stuart J.; Eck, Thomas F.; Tsay, Si-Chee

    2011-01-01

    A thorough regionally dependent understanding of optical properties of aerosols and their spatial and temporal distribution is required before we can accurately evaluate aerosol effects in the climate system. Long term measurements of aerosol optical depth, Angstrom exponent and retrieved single scattering albedo and size distribution, were analyzed and compiled into an aerosol optical properties climatology for southern Africa. Monitoring of aerosol parameters have been made by the AERONET program since the middle of the last decade in southern Africa. This valuable information provided an opportunity for understanding how aerosols of different types influence the regional radiation budget. Two long term sites, Mongu in Zambia and Skukuza in South Africa formed the core sources of data in this study. Results show that seasonal variation of aerosol optical thicknesses at 500 nm in southern Africa are characterized by low seasonal multi-month mean values (0.11 to 0.17) from December to May, medium values (0.20 to 0.27) between June and August, and high to very high values (0.30 to 0.46) during September to November. The spatial distribution of aerosol loadings shows that the north has high magnitudes than the south in the biomass burning season and the opposite in none biomass burning season. From the present aerosol data, no long term discernable trends are observable in aerosol concentrations in this region. This study also reveals that biomass burning aerosols contribute the bulk of the aerosol loading in August-October. Therefore if biomass burning could be controlled, southern Africa will experience a significant reduction in total atmospheric aerosol loading. In addition to that, aerosol volume size distribution is characterized by low concentrations in the non biomass burning period and well balanced particle size contributions of both coarse and fine modes. In contrast high concentrations are characteristic of biomass burning period, combined with

  18. Infrared Extinction Coefficients of Aerosolized Conductive Flake Powders and Flake Suspensions having a Zero-Truncated Poisson Size Distribution

    DTIC Science & Technology

    2012-11-01

    A twin-fluid atomizing nozzle was used to disseminate all materials into a stirred 190 m 3 cylindrical aerosol chamber. After dispersion by the... nozzle and thorough chamber mixing with a low speed fan, spectral aerosol transmittance and concentration were simultaneously measured to obtain spectral...varying concentrations were prepared by stirring and sonicating the powders in ethanol. A twin-fluid atomizing nozzle , consisting of a jet of the

  19. Levels and Speciation of Platinum in Size-Fractionated Atmospheric Aerosol in Urban and Rural Sites across Europe

    NASA Astrophysics Data System (ADS)

    Shafer, Martin; Antkiewicz, Dagmara; Overdier, Joel; Schauer, James

    2016-04-01

    In this study we characterized the levels and speciation of platinum in a unique set of size-resolved atmospheric aerosol (PM) samples obtained from urban environments across Europe. From April-July 2012 we collected PM from roadside canyon, roadside motorway, and background urban sites in each of six European cities (Amsterdam, Frankfurt, London, Milan, Stockholm, and Thessaloniki). A Hi-Vol sampler was used to collect PM in three size classes (>PM7, PM7-PM3, PM3) and characterized for total platinum, soluble platinum (in a suite of physiologically relevant fluids - lung fluid (ALF), Gambles saline, 0.07M HCl, and MQ) and speciated forms (colloidal and anionic) within the soluble fractions. In addition we measured 50 other elements by SF-ICPMS, soluble ions by IC, and soluble organic carbon in the PM. Order-of-magnitude differences in air concentrations of total platinum were observed between urban sites, ranging from 4 to over 45 pg/m3; with a median level of 6 pg/m3. When platinum concentrations are normalized to PM mass the cross Europe and site-to-site variability was substantially reduced - a 3-fold variation from 200 to 600 ng/g was observed. Roadside canyon sites in London, Stockholm and Thessaloniki exhibited the highest concentrations; however levels at urban background sites were remarkably similar across the cities. Relatively consistent and low concentrations (1 to 2 pg/m3) of total platinum were observed at rural background sites across Europe. The contribution of coarse particles (>7 micron and 7-3 micron) to air concentrations of total platinum was very significant (>35% at nearly all sites). Soluble platinum fractions ranged from 2 to 6% (MQ to HCl) in rural background sites to 5 to 20% (MQ to HCl) in roadway canyon sites in London and Thessaloniki; with the extractable platinum fractions a strong function of pH. With the exception of urban canyon sites in London and Thessaloniki, soluble platinum concentrations in the fine aerosol (PM3) were all

  20. A fast integrated mobility spectrometer for rapid measurement of sub-micrometer aerosol size distribution, Part I: Design and model evaluation

    DOE PAGES

    Wang, Jian; Pikridas, Michael; Spielman, Steven R.; ...

    2017-06-01

    This study discusses, a fast integrated mobility spectrometer (FIMS) was previously developed to characterize submicron aerosol size distributions at a frequency of 1 Hz and with high size resolution and counting statistics. However, the dynamic size range of the FIMS was limited to one decade in particle electrical mobility. It was proposed that the FIMS dynamic size range can be greatly increased by using a spatially varying electric field. This electric field creates regions with drastically different field strengths in the separator, such that particles of a wide diameter range can be simultaneously classified and subsequently measured. A FIMS incorporatingmore » this spatially varying electric field is developed. This paper describes the theoretical frame work and numerical simulations of the FIMS with extended dynamic size range, including the spatially varying electric field, particle trajectories, activation of separated particles in the condenser, and the transfer function, transmission efficiency, and mobility resolution. The influences of the particle Brownian motion on FIMS transfer function and mobility resolution are examined. The simulation results indicate that the FIMS incorporating the spatially varying electric field is capable of measuring aerosol size distribution from 8 to 600 nm with high time resolution. As a result, the experimental characterization of the FIMS is presented in an accompanying paper.« less

  1. Chiefs' Pocket Guide to Class Size: A Research Synthesis to Inform State Class Size Policies

    ERIC Educational Resources Information Center

    Council of Chief State School Officers, 2012

    2012-01-01

    Few questions in public education discourse benefit as much from research-based evidence as the question of class size--the pursuit of the ideal number of students that should be co-located for any particular period of instruction. But for policymakers, research on class size can be an embarrassment of riches, and much of the research appears to…

  2. 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.

  3. Final Report: Process Models of the Equilibrium Size & State of Organic/Inorganic Aerosols for the Development of Large Scale Atmospheric Models & the Analysis of Field Data

    SciTech Connect

    Wexler, Anthony Stein; Clegg, Simon Leslie

    2013-10-26

    Our work addressed the following elements of the Call for Proposals: (i) “to improve the theoretical representation of aerosol processes studied in ASP laboratory or field studies”, (ii) “to enhance the incorporation of aerosol process information into modules suitable for large-scale or global atmospheric models”, and (iii) “provide systematic experimental validation of process model predictions ... using data from targeted laboratory and field experiments”. Achievements to the end of 2012 are described in four previous reports, and include: new models of densities and surface tensions of pure (single solute) and mixed aqueous solutions of typical aerosol composition under all atmospheric conditions (0 to 100% RH and T > 150 K); inclusion of these models into the widely used Extended Aerosol Inorganics model (E-AIM, http://www.aim.env.uea.ac.uk/aim/aim.php); the addition of vapor pressure calculators for organic compounds to the E-AIM website; the ability of include user-defined organic compounds and/or lumped surrogates in gas/aerosol partitioning calculations; the development of new equations to represent the properties of soluble aerosols over the entire concentration range (using methods based upon adsorption isotherms, and derived using statistical mechanics), including systems at close to zero RH. These results are described in publications 1-6 at the end of this report, and on the “News” page of the E-AIM website (http://www.aim.env.uea.ac.uk/aim/info/news.html). During 2012 and 2013 we have collaborated in a combined observation and lab-based study of the water uptake of the organic component of atmospheric aerosols (PI Gannet Hallar, of the Desert Research Institute). The aerosol samples were analyzed using several complementary techniques (GC/MS, FT-ICR MS, and ion chromatography) to produce a very complete organic “speciation” including both polar and non-polar compounds. Hygroscopic growth factors of the samples were measured, and

  4. MATRIX (Multiconfiguration Aerosol TRacker of mIXing state): an aerosol microphysical module for global atmospheric models

    NASA Astrophysics Data System (ADS)

    Bauer, S. E.; Wright, D.; Koch, D.; Lewis, E. R.; McGraw, R.; Chang, L.-S.; Schwartz, S. E.; Ruedy, R.

    2008-05-01

    A new aerosol microphysical module MATRIX, the Multiconfiguation Aerosol TRacker of mIXing state, and its application in the Goddard Institute for Space Studies (GISS) climate model (ModelE) is described. This module, which is based on the quadrature method of moments (QMOM), represents nucleation, condensation, coagulation, internal and external mixing, and cloud-drop activation and provides aerosol particle mass and number concentration and particle size information for up to 16 mixed-mode aerosol populations. Internal and external mixing among aerosol components sulfate, nitrate, ammonium, carbonaceous aerosols, dust and sea-salt particles are represented. The solubility of each aerosol mode, which is explicitly calculated based on its soluble and insoluble components, enables calculation of the dependence of cloud drop activation on the microphysical characterization of multiple soluble modes. A detailed model description and results of box-model simulations of various mode configurations are presented. The number concentration of aerosol particles activated to cloud drops depends on the mode configuration. Simulations on the global scale with the GISS climate model are evaluated against aircraft and station measurements of aerosol mass and number concentration and particle size. The model accurately captures the observed size distributions in the aitken and accumulation modes up to particle diameter 1 μm, in which sulfate, nitrate, black and organic carbon are predominantly located; however the model underestimates coarse-mode number concentration and size, especially in the marine environment.

  5. In situ measurements of aerosol optical properties and number size distributions in a coastal region of Norway during the summer of 2008

    NASA Astrophysics Data System (ADS)

    Mogo, S.; Cachorro, V. E.; Lopez, J. F.; Montilla, E.; Torres, B.; Rodríguez, E.; Bennouna, Y.; de Frutos, A. M.

    2012-07-01

    In situ measurements of aerosol optical properties and particle size distributions were made in the summer of 2008 at the ALOMAR station facility (69°16' N, 16°00' E), located in a rural site in the north of the island of Andøya (Vesterålen archipelago), approximately 300 km north of the Arctic Circle. The extended three-month campaign was part of the POLARCAT Project (Polar Study using Aircraft, Remote Sensing, Surface Measurements and Models, of Climate, Chemistry, Aerosols, and Transport) of the International Polar Year (IPY-2007-2008). Our goal was to characterize the aerosols of this sub-Arctic area, which are frequently transported to the Arctic region. Data from 13 June to 26 August 2008 were available and the statistical data for all instruments were calculated based on the hourly averages. The overall data coverage was approximately 72%. The hourly mean values of the light-scattering coefficient, σs, and the light-absorption coefficient, σa, at 550 nm were 5.41 Mm-1 (StD = 3.55 Mm-1) and 0.40 Mm-1 (StD = 0.27 Mm-1), respectively. The scattering/absorption Ångström exponents, αs,a, were used in a detailed analysis of the variations of the spectral shape of σs,a. While αs indicates the presence of two particle sizes corresponding to two types of aerosols, αa indicates only one type of absorbing aerosol particle. αa values greater than 1 were not observed. The single-scattering albedo, ω0, ranged from 0.62 to 0.99 (mean = 0.91, StD = 0.05), and the relationships between this parameter and the absorption/scattering coefficients and the Ångström exponents are presented. Any absorption value may lead to the lowest values of ω0, whereas only the lowest scattering values were observed in the lowest range of ω0. For a given absorption value, lower ω0 were observed for smaller αs. The submicrometer, micrometer and total concentrations of the particles presented hourly mean values of 1277 cm-3 (StD = 1563 cm-3), 1 cm-3 (StD = 1 cm-3) and 2463 cm-3

  6. Cloud condensation nuclei in polluted air and biomass burning smoke near the mega-city Guangzhou, China - Part 1: Size-resolved measurements and implications for the modeling of aerosol particle hygroscopicity and CCN activity

    NASA Astrophysics Data System (ADS)

    Rose, D.; Nowak, A.; Achtert, P.; Wiedensohler, A.; Hu, M.; Shao, M.; Zhang, Y.; Andreae, M. O.; Pöschl, U.

    2010-04-01

    individual CCN efficiency spectra, the relative deviations were on average less than ~10% and hardly exceeded 20%, confirming the applicability of the κ-Köhler model approach for efficient description of the CCN activity of atmospheric aerosols. Note, however, that different types of κ-parameters must be distinguished for external mixtures of CCN-active and -inactive aerosol particles (κa, κt, κcut). Using a constant average hygroscopicity parameter (κ=0.3) and variable size distributions as measured, the deviations between observed and predicted CCN concentrations were on average less than 20%. In contrast, model calculations using variable hygroscopicity parameters as measured and constant size distributions led to much higher deviations: ~70% for the campaign average size distribution, ~80% for a generic rural size distribution, and ~140% for a generic urban size distribution. These findings confirm earlier studies suggesting that aerosol particle number and size are the major predictors for the variability of the CCN concentration in continental boundary layer air, followed by particle composition and hygroscopicity as relatively minor modulators. Depending on the required and applicable level of detail, the information and parameterizations presented in this study should enable efficient description of the CCN activity of atmospheric aerosols in detailed process models as well as in large-scale atmospheric and climate models.

  7. Self-associated submicron IgG1 particles for pulmonary delivery: effects of non-ionic surfactants on size, shape, stability, and aerosol performance.

    PubMed

    Srinivasan, Asha R; Shoyele, Sunday A

    2013-03-01

    The ability to produce submicron particles of monoclonal antibodies of different sizes and shapes would enhance their application to pulmonary delivery. Although non-ionic surfactants are widely used as stabilizers in protein formulations, we hypothesized that non-ionic surfactants will affect the shape and size of submicron IgG particles manufactured through precipitation. Submicron particles of IgG1 were produced by a precipitation process which explores the fact that proteins have minimum solubility but maximum precipitation at the isoelectric point. Non-ionic surfactants were used for size and shape control, and as stabilizing agents. Aerosol performance of the antibody nanoparticles was assessed using Andersen Cascade Impactor. Spinhaler® and Handihaler® were used as model DPI devices. SEM micrographs revealed that the shape of the submicron particles was altered by varying the type of surfactant added to the precipitating medium. Particle size as measured by dynamic light scattering was also varied based on the type and concentration of the surfactant. The surfactants were able to stabilize the IgG during the precipitation process. Polyhedral, sponge-like, and spherical nanoparticles demonstrated improved aerosolization properties compared to irregularly shaped (>20 μm) unprocessed particles. Stable antibody submicron particles of different shapes and sizes were prepared. Careful control of the shape of such particles is critical to ensuring optimized lung delivery by dry powder inhalation.

  8. Use of In Situ Cloud Condensation Nuclei, Extinction, and Aerosol Size Distribution Measurements to Test a Method for Retrieving Cloud Condensation Nuclei Profiles From Surface Measurements

    NASA Technical Reports Server (NTRS)

    Ghan, Stephen J.; Rissman, Tracey A.; Ellman, Robert; Ferrare, Richard A.; Turner, David; Flynn, Connor; Wang, Jian; Ogren, John; Hudson, James; Jonsson, Haflidi H.; VanReken, Timothy; Flagan, Richard C.; Seinfeld, John H.

    2006-01-01

    If the aerosol composition and size distribution below cloud are uniform, the vertical profile of cloud condensation nuclei (CCN) concentration can be retrieved entirely from surface measurements of CCN concentration and particle humidification function and surface-based retrievals of relative humidity and aerosol extinction or backscatter. This provides the potential for long-term measurements of CCN concentrations near cloud base. We have used a combination of aircraft, surface in situ, and surface remote sensing measurements to test various aspects of the retrieval scheme. Our analysis leads us to the following conclusions. The retrieval works better for supersaturations of 0.1% than for 1% because CCN concentrations at 0.1% are controlled by the same particles that control extinction and backscatter. If in situ measurements of extinction are used, the retrieval explains a majority of the CCN variance at high supersaturation for at least two and perhaps five of the eight flights examined. The retrieval of the vertical profile of the humidification factor is not the major limitation of the CCN retrieval scheme. Vertical structure in the aerosol size distribution and composition is the dominant source of error in the CCN retrieval, but this vertical structure is difficult to measure from remote sensing at visible wavelengths.

  9. Measurement of C{sub 24}H{sub 14} polycyclic aromatic hydrocarbons associated with a size-segregated urban aerosol

    SciTech Connect

    Allen, J.O.; Dookeran, N.M.; Sarofim, A.F.; Smith, K.A.; Taghizadeh, K.; Plummer, E.F.; Lafleur, A.L.; Durant, J.L.

    1998-07-01

    Six-ring C{sub 24}H{sub 14} (MW 302) polycyclic aromatic hydrocarbons (PAH), some of which are potent mutagens, are present in urban aerosols. Size-segregated atmospheric aerosol samples from Boston, MA, were analyzed for C{sub 24}H{sub 14} PAH by gas chromatography/mass spectrometry. Eleven peaks were found with mass to charge ratios of 302; of these, eight were identified using authentic standards. Five of the peaks were quantified. For each of these five, the distributions with respect to particle size were bimodal with the majority of the mass associated with accumulation mode particles and a smaller fraction of the mass associated with ultrafine mode particles. These distributions are similar to those observed for PAH of molecular weight 252--278 in the same sample but different from those of benzo[ghi]perylene and coronene which were associated to a greater degree with ultrafine particles. The data suggest that C{sub 24}H{sub 14} PAH repartition to larger particles by vaporization and sorption more rapidly than do benzo[ghi]perylene and coronene. The total concentration of C{sub 24}H{sub 14} PAH was comparable to that of benzo[a]pyrene in the same sample. Because of their mutagenicities, C{sub 24}H{sub 14} PAH may make a contribution to the genotoxicity of urban aerosols comparable to that of benzo[a]pyrene.

  10. Sensitivity of depositions to the size and hygroscopicity of Cs-bearing aerosols released from the Fukushima nuclear accident

    NASA Astrophysics Data System (ADS)

    Kajino, Mizuo; Adachi, Kouji; Sekiyama, Tsuyoshi; Zaizen, Yuji; Igarashi, Yasuhito

    2014-05-01

    We recently revealed that the microphysical properties of aerosols carrying the radioactive Cs released from the Fukushima Daiichi Nuclear Power Plant (FDNPP) at an early stage (March 14-15, 2011) of the accident could be very different from what we assumed previously: super-micron and non-hygroscopic at the early stage, whereas sub-micron and hygroscopic afterwards (at least later than March 20-22). In the study, two sensitivity simulations with the two different aerosol microphysical properties were conducted using a regional scale meteorology- chemical transport model (NHM-Chem). The impact of the difference was quite significant. 17% (0.001%) of the radioactive Cs fell onto the ground by dry (wet) deposition processes, and the rest was deposited into the ocean or was transported out of the model domain, which is central and northern part of the main land of Japan, under the assumption that Cs-bearing aerosols are non-hygroscopic and super-micron. On the other hand, 5.7% (11.3%) fell onto the ground by dry (wet) deposition, for the cases under the assumption that the Cs-bearing aerosols are hygroscopic and sub-micron. For the accurate simulation of the deposition of radionuclides, knowledge of the aerosol microphysical properties is essential as well as the accuracy of the simulated wind fields and precipitation patterns.

  11. Organic Composition of PM2.5 and Size-Segregated Aerosols During the 2002 Bay Regional Atmospheric Chemistry Experiment (BRACE), Florida, USA

    NASA Astrophysics Data System (ADS)

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

    2003-12-01

    Aerosol samples were collected for the analysis of organic source markers using a Tisch Environmental PM2.5 high volume sampler and two Micro Orifice Uniform Deposit Impactors (MOUDIs) as part of the Bay Regional Atmospheric Chemistry Experiment (BRACE) in Tampa, Florida. PM2.5 samples were collected at ground level on quartz fiber filters (QFF) while size-segregated samples were collected 12 meter above ground level on aluminum foil discs. MOUDIs with aerodynamic cut diameters of 18, 10, 5.6, 3.2, 1.8, 1.0, 0.56, 0.32 and 0.17 um were used. Samples were collected on a 24 hour schedule. The collected samples were solvent extracted using a mixture of dichloromethane/acetone/hexane, concentrated and then analyzed using a gas chromatograph/mass spectrometer (GC/MS) operated in single ion mode. PM2.5 extracts were analyzed using conventional splitless low volume injections (1 ul). Size-segregated aerosol extracts were analyzed using a Hewlett-Packard Programmable Temperature Vaporizing inlet (PTV) combined with large volume injections (80ul). Excellent chromatographic resolutions were obtained with either a 30 or 60 meter long RTX-5MS, 0.25 mm I.D. column. Target compounds were chosen to cover the range of potential sources and included alkanes and polycyclic aromatic hydrocarbons (PAH). Investigation of potential aerosol sources for different particle sizes using known organic markers and source profiles will be presented. Relationship between the collected PM2.5 and size-segregated samples will be studied. Size distributions of carbon preference indices (CPI), percent wax n-alkanes (%WNA) and concentration of selected compounds will be discussed.

  12. MATRIX (Multiconfiguration Aerosol TRacker of mIXing state): an aerosol microphysical module for global atmospheric models

    NASA Astrophysics Data System (ADS)

    Bauer, S. E.; Wright, D. L.; Koch, D.; Lewis, E. R.; McGraw, R.; Chang, L.-S.; Schwartz, S. E.; Ruedy, R.

    2008-10-01

    A new aerosol microphysical module MATRIX, the Multiconfiguration Aerosol TRacker of mIXing state, and its application in the Goddard Institute for Space Studies (GISS) climate model (ModelE) are described. This module, which is based on the quadrature method of moments (QMOM), represents nucleation, condensation, coagulation, internal and external mixing, and cloud-drop activation and provides aerosol particle mass and number concentration and particle size information for up to 16 mixed-mode aerosol populations. Internal and external mixing among aerosol components sulfate, nitrate, ammonium, carbonaceous aerosols, dust and sea-salt particles are represented. The solubility of each aerosol population, which is explicitly calculated based on its soluble and insoluble components, enables calculation of the dependence of cloud drop activation on the microphysical characterization of multiple soluble aerosol populations. A detailed model description and results of box-model simulations of various aerosol population configurations are presented. The box model experiments demonstrate the dependence of cloud activating aerosol number concentration on the aerosol population configuration; comparisons to sectional models are quite favorable. MATRIX is incorporated into the GISS climate model and simulations are carried out primarily to assess its performance/efficiency for global-scale atmospheric model application. Simulation results were compared with aircraft and station measurements of aerosol mass and number concentration and particle size to assess the ability of the new method to yield data suitable for such comparison. The model accurately captures the observed size distributions in the Aitken and accumulation modes up to particle diameter 1 μm, in which sulfate, nitrate, black and organic carbon are predominantly located; however the model underestimates coarse-mode number concentration and size, especially in the marine environment. This is more likely due to

  13. Fluorescent Biological Aerosol Particle Concentrations and Size Distributions Measured with an Ultraviolet Aerodynamic Particle Sizer (UV-APS) in Central Europe

    NASA Astrophysics Data System (ADS)

    Huffman, J. A.; Treutlein, B.; Pöschl, U.

    2009-12-01

    Primary biological aerosol particles (PBAPs), including bacteria, spores and pollen, are essential for the spread of organisms and disease in the biosphere, and numerous studies have suggested that they may be important for atmospheric processes, including the formation of clouds and precipitation. The atmospheric abundance and size distribution of PBAPs, however, are largely unknown. At a semi-urban site in Mainz, Germany, we used an ultraviolet aerodynamic particle sizer (UV-APS) to measure fluorescent biological aerosol particles (FBAPs), which can be regarded as viable bioaerosol particles representing a lower limit for the actual abundance of PBAPs. Fluorescence of non-biological aerosol components are likely to influence the measurement results obtained for fine particles (< 1 µm), but not for coarse particles (1 - 20 µm). Averaged over the four-month measurement period (August - December 2006), the mean number concentration of coarse FBAPs was ~3x10-2 cm-3, corresponding to ~4% of total coarse particle number [1]. The mean mass concentration of FBAPs was ~1 µg m-3, corresponding to ~20% of total coarse particle mass. The FBAP number size distributions exhibited alternating patterns with peaks at various diameters. A pronounced peak at ~3 µm was essentially always observed and can be described by the following campaign-average lognormal fit parameters: geometric mean diameter 3.2 µm, geometric standard deviation 1.3, number concentration 1.6 x 10-2 cm-3. This peak is likely due to fungal spores or agglomerated bacteria, and it exhibited a pronounced diel cycle with maximum intensity during early/mid-morning. FBAP peaks around ~1.5 µm, ~5 µm, and ~13 µm were also observed, but less pronounced and less frequent. These may be explained by single bacterial cells, larger fungal spores, and pollen grains, respectively. The observed number concentrations and characteristic sizes of FBAPs are consistent with microscopic, biological and chemical analyses of

  14. Fluorescent biological aerosol particle concentrations and size distributions measured with an ultraviolet aerodynamic particle sizer (UV-APS) in Central Europe

    NASA Astrophysics Data System (ADS)

    Huffman, J. A.; Treutlein, B.; Pöschl, U.

    2009-08-01

    Primary biological aerosol particles (PBAPs), including bacteria, spores and pollen, are essential for the spread of organisms and disease in the biosphere, and numerous studies have suggested that they may be important for atmospheric processes, including the formation of clouds and precipitation. The atmospheric abundance and size distribution of PBAPs, however, are largely unknown. At a semi-urban site in Mainz, Germany, we used an ultraviolet aerodynamic particle sizer (UV-APS) to measure fluorescent biological aerosol particles (FBAPs), which can be regarded as viable bioaerosol particles representing a lower limit for the actual abundance of PBAPs. Fluorescence of non-biological aerosol components are likely to influence the measurement results obtained for fine particles (<1 μm), but not for coarse particles (1-20 μm). Averaged over the four-month measurement period (August-December 2006), the mean number concentration of coarse FBAPs was ~3×10-2 cm-3, corresponding to ~4% of total coarse particle number. The mean mass concentration of FBAPs was ~1 μg m-3, corresponding to ~20% of total coarse particle mass. The FBAP number size distributions exhibited alternating patterns with peaks at various diameters. A pronounced peak at ~3 μm was essentially always observed and can be described by the following campaign-average lognormal fit parameters: geometric mean diameter 3.2 μm, geometric standard deviation 1.3, number concentration 1.6×10-2 cm-3. This peak is likely due to fungal spores or agglomerated bacteria, and it exhibited a pronounced diel cycle with maximum intensity during early/mid-morning. FBAP peaks around ~1.5 μm, ~5 μm, and ~13 μm were also observed, but less pronounced and less frequent. These may be explained by single bacterial cells, larger fungal spores, and pollen grains, respectively. The observed number concentrations and characteristic sizes of FBAPs are consistent with microscopic, biological and chemical analyses of PBAPs in

  15. Fluorescent biological aerosol particle concentrations and size distributions measured with an Ultraviolet Aerodynamic Particle Sizer (UV-APS) in Central Europe

    NASA Astrophysics Data System (ADS)

    Huffman, J. A.; Treutlein, B.; Pöschl, U.

    2010-04-01

    Primary Biological Aerosol Particles (PBAPs), including bacteria, spores and pollen, are essential for the spread of organisms and disease in the biosphere, and numerous studies have suggested that they may be important for atmospheric processes, including the formation of clouds and precipitation. The atmospheric abundance and size distribution of PBAPs, however, are largely unknown. At a semi-urban site in Mainz, Germany we used an Ultraviolet Aerodynamic Particle Sizer (UV-APS) to measure Fluorescent Biological Aerosol Particles (FBAPs), which provide an estimate of viable bioaerosol particles and can be regarded as an approximate lower limit for the actual abundance of PBAPs. Fluorescence of non-biological aerosol components are likely to influence the measurement results obtained for fine particles (<1 μm), but not for coarse particles (1-20 μm). Averaged over the four-month measurement period (August-December 2006), the mean number concentration of coarse FBAPs was ~3×10-2 cm-3, corresponding to ~4% of total coarse particle number. The mean mass concentration of FBAPs was ~1μg m-3, corresponding to ~20% of total coarse particle mass. The FBAP number size distributions exhibited alternating patterns with peaks at various diameters. A pronounced peak at ~3 μm was essentially always observed and can be described by the following campaign-average lognormal fit parameters: geometric mean diameter 3.2 μm, geometric standard deviation 1.3, number concentration 1.6×10-2 cm-3. This peak is likely due to fungal spores or agglomerated bacteria, and it exhibited a pronounced diel cycle (24-h) with maximum intensity during early/mid-morning. FBAP peaks around ~1.5 μm, ~5 μm, and ~13 μm were also observed, but less pronounced and less frequent. These may be single bacterial cells, larger fungal spores, and pollen grains, respectively. The observed number concentrations and characteristic sizes of FBAPs are consistent with microscopic, biological and chemical

  16. Ambient aerosol analysis using aerosol-time-of-flight mass spectrometry

    SciTech Connect

    Prather, K.A.; Noble, C.A.; Liu, D.Y.; Silva, P.J.; Fergenson, D.F.

    1996-10-01

    We have recently developed a technique, Aerosol-Time-of-Flight Mass Spectrometry (ATOFMS), which is capable of real-time determination of the aerodynamic size and chemical composition of individual aerosol particles. In order to obtain such information, the techniques of aerodynamic particle sizing and time-of-flight mass spectrometry are combined in a single instrument. ATOFMS is being used for the direct analysis of ambient aerosols with the goal of establishing correlations between particle size and chemical composition. Currently, measurements are being made to establish potential links between the presence of particular types of particles with such factors as the time of day, weather conditions, and concentration levels of gaseous smog components such as NO{sub x} and ozone. This data will be used to help establish a better understanding of tropospheric gas-aerosol processes. This talk will discuss the operating principles of ATOFMS as well as present the results of ambient analysis studies performed in our laboratory.

  17. Investigation of aviation emission impacts on global tropospheric chemistry and climate using a size-resolved aerosol-chemistry model

    NASA Astrophysics Data System (ADS)

    Kapadia, Zarashpe; Spracklen, Dominick; Arnold, Stephen; Borman, Duncan; Mann, Graham; Pringle, Kirsty; Monks, Sarah; Reddington, Carly; Rap, Alexandru; Scott, Catherine

    2014-05-01

    Aviation is responsible for 3% of global anthropogenic CO2 emissions, but 2-14% of anthropogenic induced climate warming due to contributions from short lived climate forcers. The global civil aviation fleet is projected to double by 2026 in relation to a 2006 baseline and so will play a substantial role in future climate change. Uncertainty in the net impact of aviation on climate is largely due to uncertainty in the impacts of aviation emissions on ozone and aerosol. To study the impact of aviation emissions we use the GLOMAP-mode global aerosol microphysics model coupled to the 3-D chemical transport model TOMCAT. GLOMAP-mode has been extended to include treatment of nitrate aerosol. We include a full suite of non-CO2 aviation emissions (including NOX, SO2, HCs, BC and OC) in the model. We combined the simulated changes in ozone and aerosol with a 3D radiative transfer model to quantify the radiative effect due to aviation non-CO2 emissions. We find that aviation emissions increase O3 concentrations by up to 5.3% in the upper troposphere (UT), broadly matching previous studies. Black carbon (BC) and organic carbon (OC) concentrations increase by 26.5% and 14.6% respectively in the UT, whereas nitrate aerosol is reduced in some regions due to co-emission of NOX and SO2 In the UT, aviation emissions increase both total aerosol number as well as the concentration of particles greater than 70 nm diameter (N70). Entrainment of these particles into the free troposphere results in aviation emissions also increasing N70 in the boundary layer, causing a cooling through the first aerosol indirect effect. We explore differences in these responses compared with those simulated when using the recommended aviation emissions from CMIP5 (5th Climate Model Intercomparison Project), which only include NOX and BC emissions. Our results suggest that aviation emissions of SO2 and HCs neglected by CMIP5 produce important effects on ozone, aerosol number, and N70. We suggest CMIP5

  18. One-year observations of size distribution characteristics of major aerosol constituents at a coastal receptor site in Hong Kong - Part 1: Inorganic ions and oxalate

    NASA Astrophysics Data System (ADS)

    Bian, Q.; Huang, X. H. H.; Yu, J. Z.

    2014-09-01

    Size distribution data of major aerosol constituents are essential in source apportioning of visibility degradation, testing and verification of air quality models incorporating aerosols. We report here 1-year observations of mass size distributions of major inorganic ions (sulfate, nitrate, chloride, ammonium, sodium, potassium, magnesium and calcium) and oxalate at a coastal suburban receptor site in Hong Kong, China. A total of 43 sets of size-segregated samples in the size range of 0.056-18 μm were collected from March 2011 to February 2012. The size distributions of sulfate, ammonium, potassium and oxalate were characterized by a dominant droplet mode with a mass mean aerodynamic diameter (MMAD) in the range of ~ 0.7-0.9 μm. Oxalate had a slightly larger MMAD than sulfate on days with temperatures above 22 °C as a result of the process of volatilization and repartitioning. Nitrate was mostly dominated by the coarse mode but enhanced presence in fine mode was detected on winter days with lower temperature and lower concentrations of sea salt and soil particles. This data set reveals an inversely proportional relationship between the fraction of nitrate in the fine mode and product of the sum of sodium and calcium in equivalent concentrations and the dissociation constant of ammonium nitrate (i.e., (1/([Na+] + 2[Ca2+]) × (1/Ke')) when Pn_fine is significant (> 10%). The seasonal variation observed for sea salt aerosol abundance, with lower values in summer and winter, is possibly linked with the lower marine salinities in these two seasons. Positive matrix factorization was applied to estimate the relative contributions of local formation and transport to the observed ambient sulfate level through the use of the combined data sets of size-segregated sulfate and select gaseous air pollutants. On average, the regional/super-regional transport of air pollutants was the dominant source at this receptor site, especially on high-sulfate days while local formation

  19. One-year observations of size distribution characteristics of major aerosol constituents at a coastal receptor site in Hong Kong - Part 1: Inorganic ions and oxalate

    NASA Astrophysics Data System (ADS)

    Bian, Q.; Huang, X. H. H.; Yu, J. Z.

    2014-01-01

    Size distribution data of major aerosol constituents are essential in source apportioning of visibility degradation, testing and verification of air quality models incorporating aerosols. We report here one-year observations of mass size distributions of major inorganic ions (sulfate, nitrate, chloride, ammonium, sodium, potassium, magnesium and calcium) and oxalate at a coastal suburban receptor site in Hong Kong, China. A total of 43 sets of size segregated samples in the size range of 0.056-18 μm were collected from March 2011 to February 2012. The size distributions of sulfate, ammonium, potassium and oxalate were characterized by a dominant droplet mode with a mass mean aerodynamic diameter (MMAD) in the range of ~0.7-0.9 μm. Oxalate had a slightly larger MMAD than sulfate on days with temperatures above 22 °C as a result of the process of volatilization and repartitioning. Nitrate was mostly dominated by the coarse mode but enhanced presence in fine mode was detected on winter days with lower temperature and lower concentrations of sea salt and soil particles. This data set reveals an inversely proportional relationship between the fraction of nitrate in the fine mode and product of the sum of sodium and calcium in equivalent concentrations and the dissociation constant of ammonium nitrate (i.e., (1/[Na+] + 2[Ca2+]) × (1/Ke')). The seasonal variation observed for sea salt aerosol abundance, with lower values in summer and winter, is possibly linked with the lower marine salinities in these two seasons. Positive matrix factorization was applied to estimate the relative contributions of local formation and transport to the observed ambient sulfate level through the use of the combined datasets of size-segregated sulfate and select gaseous air pollutants. On average, the regional/super-regional transport of air pollutants was the dominant source at this receptor site, especially on high sulfate days, while local formation processes contributed approximately

  20. Test-Aerosol Generator For Calibrating Particle Counters

    NASA Technical Reports Server (NTRS)

    Mogan, Paul A.; Adams, Alois J.; Schwindt, Christian J.; Hodge, Timothy R.; Mallow, Tim J.; Duong, Anh A.; Bukauskas, Vyto V.

    1996-01-01

    Apparatus generates clean, stable aerosol stream for use in testing and calibrating laser-based aerosol-particle counter. Size and concentration of aerosol particles controlled to ensure accurate calibration. Cheap, widely available medical nebulizers used to generate aerosols.

  1. Aerosol size distributions retrieved from multiband transmissometer data in the southern Baltic Sea during the VAMPIRA trials

    NASA Astrophysics Data System (ADS)

    de Jong, Arie N.; van Eijk, Alexander M. J.; Moerman, Marcel M.; Cohen, Leo H.

    2006-09-01

    In an earlier paper [1], data from our Multi-Band Radiometer Transmissometer (MSRT) were used to compare the ratio of extinction coefficients in different spect