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Sample records for aerosol particles measured

  1. 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.

  2. Workplace aerosol mass concentration measurement using optical particle counters.

    PubMed

    Görner, Peter; Simon, Xavier; Bémer, Denis; Lidén, Göran

    2012-02-01

    Direct-reading aerosol measurement usually uses the optical properties of airborne particles to detect and measure particle concentration. In the case of occupational hygiene, mass concentration measurement is often required. Two aerosol monitoring methods are based on the principle of light scattering: optical particle counting (OPC) and photometry. The former analyses the light scattered by a single particle, the latter by a cloud of particles. Both methods need calibration to transform the quantity of scattered light detected into particle concentration. Photometers are simpler to use and can be directly calibrated to measure mass concentration. However, their response varies not only with aerosol concentration but also with particle size distribution, which frequently contributes to biased measurement. Optical particle counters directly measure the particle number concentration and particle size that allows assessment of the particle mass provided the particles are spherical and of known density. An integrating algorithm is used to calculate the mass concentration of any conventional health-related aerosol fraction. The concentrations calculated thus have been compared with simultaneous measurements by conventional gravimetric sampling to check the possibility of field OPC calibration with real workplace aerosols with a view to further monitoring particle mass concentration. Aerosol concentrations were measured in the food industry using the OPC GRIMM® 1.108 and the CIP 10-Inhalable and CIP 10-Respirable (ARELCO®) aerosol samplers while meat sausages were being brushed and coated with calcium carbonate. Previously, the original OPC inlet had been adapted to sample inhalable aerosol. A mixed aerosol of calcium carbonate and fungi spores was present in the workplace. The OPC particle-size distribution and an estimated average particle density of both aerosol components were used to calculate the mass concentration. The inhalable and respirable aerosol fractions

  3. SAGE II aerosol validation - Selected altitude measurements, including particle micromeasurements

    NASA Technical Reports Server (NTRS)

    Oberbeck, Verne R.; Russell, Philip B.; Pueschel, Rudolf F.; Snetsinger, Kenneth G.; Ferry, Guy V.; Livingston, John M.; Rosen, James N.; Osborn, Mary T.; Kritz, Mark A.

    1989-01-01

    The validity of particulate extinction coefficients derived from limb path solar radiance measurements obtained during the Stratospheric Aerosol and Gas Experiment (SAGE) II is tested. The SAGE II measurements are compared with correlative aerosol measurements taken during January 1985, August 1985, and July 1986 with impactors, laser spectrometers, and filter samplers on a U-2 aircraft, an upward pointing lidar on a P-3 aircraft, and balloon-borne optical particle counters. The data for July 29, 1986 are discussed in detail. The aerosol measurements taken on this day at an altitude of 20.5 km produce particulate extinction values which validate the SAGE II values for similar wavelengths.

  4. Measurement of mass distribution of chemical species in aerosol particles

    NASA Technical Reports Server (NTRS)

    Sinha, M. P.; Friedlander, S. K.

    1984-01-01

    Aerosols may be generated through the nebulizing of solutions and the evaporation of their solvent, leaving the dry solute particles. Attention is presently given to a method for the direct determination of the masses of chemical species in individual aerosol particles on a continuous, real-time basis, using mass spectrometry. After the aerosol particles are introduced into the ion source of a quadrupole mass spectrometer, the particles impinge on a hot rhenium filament in the mass spectrometer's ion source. The resulting vapor plume is ionized by electron bombardment, and a pulse of ions is generated by each particle. The intensities of different masses in the ion pulses can then be measured by the mass spectrometer.

  5. New mass measurement method of aerosol particle using vibrating probe particle controlled by radiation pressure

    NASA Astrophysics Data System (ADS)

    Hariyama, Tatsuo; Takaya, Yasuhiro; Miyoshi, Takashi

    2005-11-01

    Aerosol particles with sub-micro meter size inhaled into respiratory systems cause serious damage to human body. In order to evaluate the health effects of the particles, classification methods of the particles with size and mass are needed. Several measurement methods of the particle size are established. However, conventional mass measurement methods are not enough to measure the particles with sub- pico gram. We propose a new mass measurement method of the aerosol particles based on laser trapping. In this method, an optically trapped silica particle is used as a measuring probe particle. The probe particle is trapped at a beam waist of the focused laser light and is forced to vibrate by deflecting the beam waist using AOD. The vibrating probe particle has a resonance frequency because it is governed by the spring-mass-damper system. When an aerosol particle is attached to the probe particle, the resonance frequency shifts according to the increase of the total mass. The mass of the aerosol particle can be measured from the shift of the resonance frequency. Experimentally, it is confirmed that the probe particle is governed by the spring-mass-damper system and has a resonance frequency. When a silica fine particle of 3pg in mass used as an aerosol particle is attached to the probe particle, the resonance frequency shift occurs as expected in the dynamic system and the fine particle mass can be measured based on the proposed method.

  6. Time Resolved Measurements of Primary Biogenic Aerosol Particles in Amazonia

    NASA Astrophysics Data System (ADS)

    Wollny, A. G.; Garland, R.; Pöschl, U.

    2009-04-01

    Biogenic aerosols are ubiquitous in the Earth's atmosphere and they influence atmospheric chemistry and physics, the biosphere, climate, and public health. They play an important role in the spread of biological organisms and reproductive materials, and they can cause or enhance human, animal, and plant diseases. Moreover, they influence the Earth's energy budget by scattering and absorbing radiation, and they can initiate the formation of clouds and precipitation as cloud condensation and ice nuclei. The composition, abundance, and origin of biogenic aerosol particles and components are, however, still not well understood and poorly quantified. Prominent examples of primary biogenic aerosol particles, which are directly emitted from the biosphere to the atmosphere, are pollen, bacteria, fungal spores, viruses, and fragments of animals and plants. During the Amazonian Aerosol Characterization Experiment (AMAZE-08) a large number of aerosol and gas-phase measurements were taken on a remote site close to Manaus, Brazil, during a period of five weeks in February and March 2008. This presented study is focused on data from an ultraviolet aerodynamic particle sizer (UVAPS, TSI inc.) that has been deployed for the first time in Amazonia. In this instrument, particle counting and aerodynamic sizing over the range of 0.5-20 µm are complemented by the measurement of UV fluorescence at 355 nm (excitation) and 420-575 nm (emission), respectively. Fluorescence at these wavelengths is characteristic for reduced pyridine nucleotides (e.g., NAD(P)H) and for riboflavin, which are specific for living cells. Thus particles exhibiting fluorescence signals can be regarded as "viable aerosols" or "fluorescent bioparticles" (FBAP), and their concentration can be considered as lower limit for the actual abundance of primary biogenic aerosol particles. Data from the UVAPS were averaged over 5 minute time intervals. The presence of bioparticles in the observed size range has been

  7. Novel Measurements of Aerosol Particle Interfaces Using Biphasic Microfluidics

    NASA Astrophysics Data System (ADS)

    Metcalf, A. R.; Dutcher, C. S.

    2014-12-01

    Secondary organic aerosol (SOA) particles are nearly ubiquitous in the atmosphere and yet there remains large uncertainties in their formation processes and ambient properties. These particles are complex microenvironments, which can contain multiple interfaces due to internal aqueous-organic phase partitioning and to the external liquid-vapor surface. These aerosol interfaces can profoundly affect the fate of condensable organic compounds emitted into the atmosphere by altering the way in which organic vapors interact with the ambient aerosol. Aerosol interfaces affect particle internal structure, species uptake, equilibrium partitioning, activation to cloud condensation or ice nuclei, and optical properties. For example, organic thin films can shield the core of the aerosol from the ambient environment, which may disrupt equilibrium partitioning and mass transfer. To improve our ability to accurately predict the fate of SOA in the atmosphere, we must improve our knowledge of aerosol interfaces and their interactions with the ambient environment. Few technologies exist to accurately probe aerosol interfaces at atmospherically-relevant conditions. In this talk, a novel method using biphasic microscale flows will be introduced for generating, trapping, and perturbing complex interfaces at atmospherically relevant conditions. These microfluidic experiments utilize high-speed imaging to monitor interfacial phenomena at the microscale and are performed with phase contrast and fluorescence microscopy on a temperature-controlled inverted microscope stage. From these experiments, interfacial thermodynamic properties such as surface tension, rheological properties such as interfacial moduli, and kinetic properties such as mass transfer coefficients can be measured or inferred. Chemical compositions of the liquid phases studied here span a range of viscosities and include electrolyte and water soluble organic acid species often observed in the atmosphere, such as mixtures

  8. Continuous measurements of aerosol particles in Arctic Russia and Finland

    NASA Astrophysics Data System (ADS)

    Asmi, Eija; Kondratyev, Vladimir; Brus, David; Lihavainen, Heikki; Laurila, Tuomas; Aurela, Mika; Hatakka, Juha; Viisanen, Yrjö; Reshetnikov, Alexander; Ivakhov, Victor; Uttal, Taneil; Makshtas, Alexander

    2013-04-01

    The Arctic and northern boreal regions of Eurasia are experiencing rapid environmental changes due to pressures by human activities. The largest anthropogenic climate forcings are due to aerosol particles and greenhouse gases (GHGs). The Arctic environment is highly sensitive to changes in aerosol concentrations or composition, largely due to the high surface reflectance for the most part of the year. Concentrations of aerosols in winter and spring Arctic are affected by 'Arctic Haze', a phenomenon suggested to arise from the transport of pollutants from lower latitudes and further strengthened by the strong stratification of the Arctic wintertime atmosphere. Sources and transport patterns of aerosols into the Arctic are, however, not fully understood. In order to monitor the changes within the Arctic region, as well as to understand the sources and feedback mechanisms, direct measurements of aerosols within the Arctic are needed. So far, direct year-round observations have been inadequate especially within the Russian side of the Arctic. This is the reason why a new climate observatory was founded in Tiksi, Russia. Tiksi meteorological observatory in northern Siberia (71o 36' N; 128o 53' E) on the shore of the Laptev Sea has been operating since 1930s. Recently, it was upgraded and joint in the network of the IASOA, in the framework of the International Polar Year Activity project. The project is run in collaboration between National Oceanic and Atmospheric Administration (NOAA) with the support of the National Science Foundation (NSF), Roshydromet (AARI and MGO units), government of the Republic of Sakha (Yakutia) and the Finnish Meteorological Institute (FMI). The research activities of FMI in Tiksi include e.g. continuous long-term measurements of aerosol physical properties, which have been successfully continued since summer 2010. These, together with the FMI measurements in Pallas station in northern Finland since 1999, provide important information on the

  9. SAGE II aerosol validation: selected altitude measurements, including particle micromeasurements.

    PubMed

    Oberbeck, V R; Livingston, J M; Russell, P B; Pueschel, R F; Rosen, J N; Osborn, M T; Kritz, M A; Snetsinger, K G; Ferry, G V

    1989-06-20

    Correlative aerosol measurements taken at a limited number of altitudes during coordinated field experiments are used to test the validity of particulate extinction coefficients derived from limb path solar radiance measurements taken by the Stratospheric Aerosol and Gas Experiment (SAGE) II Sun photometer. In particular, results are presented from correlative measurement missions that were conducted during January 1985, August 1985, and July 1986. Correlative sensors included impactors, laser spectrometers, and filter samplers aboard an U-2-airplane, an upward pointing lidar aboard a P-3 airplane, and balloon-borne optical particle counters (dustsondes). The main body of this paper focuses on the July 29, 1986, validation experiment, which minimized the many difficulties (e.g., spatial and temporal inhomogeneities, imperfect coincidences) that can complicate the validation process. On this day, correlative aerosol measurements taken at an altitude of 20.5 km agreed with each other within their respective uncertainties, and particulate extinction values calculated at SAGE II wavelengths from these measurements validated corresponding SAGE II values. Additional validation efforts on days when measurement and logistical conditions were much less favorable for validation are discussed in an appendix.

  10. Diffusivity measurements of volatile organics in levitated viscous aerosol particles

    NASA Astrophysics Data System (ADS)

    Bastelberger, Sandra; Krieger, Ulrich K.; Luo, Beiping; Peter, Thomas

    2017-07-01

    Field measurements indicating that atmospheric secondary organic aerosol (SOA) particles can be present in a highly viscous, glassy state have spurred numerous studies addressing low diffusivities of water in glassy aerosols. The focus of these studies is on kinetic limitations of hygroscopic growth and the plasticizing effect of water. In contrast, much less is known about diffusion limitations of organic molecules and oxidants in viscous matrices. These may affect atmospheric chemistry and gas-particle partitioning of complex mixtures with constituents of different volatility. In this study, we quantify the diffusivity of a volatile organic in a viscous matrix. Evaporation of single particles generated from an aqueous solution of sucrose and small amounts of volatile tetraethylene glycol (PEG-4) is investigated in an electrodynamic balance at controlled relative humidity (RH) and temperature. The evaporative loss of PEG-4 as determined by Mie resonance spectroscopy is used in conjunction with a radially resolved diffusion model to retrieve translational diffusion coefficients of PEG-4. Comparison of the experimentally derived diffusivities with viscosity estimates for the ternary system reveals a breakdown of the Stokes-Einstein relationship, which has often been invoked to infer diffusivity from viscosity. The evaporation of PEG-4 shows pronounced RH and temperature dependencies and is severely depressed for RH ≲ 30 %, corresponding to diffusivities < 10-14 cm2 s-1 at temperatures < 15 °C. The temperature dependence is strong, suggesting a diffusion activation energy of about 300 kJ mol-1. We conclude that atmospheric volatile organic compounds can be subject to severe diffusion limitations in viscous organic aerosol particles. This may enable an important long-range transport mechanism for organic material, including pollutant molecules such as polycyclic aromatic hydrocarbons (PAHs).

  11. Measurement of the nucleation of atmospheric aerosol particles.

    PubMed

    Kulmala, Markku; Petäjä, Tuukka; Nieminen, Tuomo; Sipilä, Mikko; Manninen, Hanna E; Lehtipalo, Katrianne; Dal Maso, Miikka; Aalto, Pasi P; Junninen, Heikki; Paasonen, Pauli; Riipinen, Ilona; Lehtinen, Kari E J; Laaksonen, Ari; Kerminen, Veli-Matti

    2012-09-01

    The formation of new atmospheric aerosol particles and their subsequent growth have been observed frequently at various locations all over the world. The atmospheric nucleation rate (or formation rate) and growth rate (GR) are key parameters to characterize the phenomenon. Recent progress in measurement techniques enables us to measure atmospheric nucleation at the size (mobility diameter) of 1.5 (±0.4) nm. The detection limit has decreased from 3 to 1 nm within the past 10 years. In this protocol, we describe the procedures for identifying new-particle-formation (NPF) events, and for determining the nucleation, formation and growth rates during such events under atmospheric conditions. We describe the present instrumentation, best practices and other tools used to investigate atmospheric nucleation and NPF at a certain mobility diameter (1.5, 2.0 or 3.0 nm). The key instruments comprise devices capable of measuring the number concentration of the formed nanoparticles and their size, such as a suite of modern condensation particle counters (CPCs) and air ion spectrometers, and devices for characterizing the pre-existing particle number concentration distribution, such as a differential mobility particle sizer (DMPS). We also discuss the reliability of the methods used and requirements for proper measurements and data analysis. The time scale for realizing this procedure is 1 year.

  12. Decomposition of Atmospheric Aerosol Phase Function by Particle Size and Morphology via Single Particle Scattering Measurements

    NASA Astrophysics Data System (ADS)

    Aptowicz, K. B.; Pan, Y.; Martin, S.; Fernandez, E.; Chang, R.; Pinnick, R. G.

    2013-12-01

    We report upon an experimental approach that provides insight into how particle size and shape affect the scattering phase function of atmospheric aerosol particles. Central to our approach is the design of an apparatus that measures the forward and backward scattering hemispheres (scattering patterns) of individual atmospheric aerosol particles in the coarse mode range. The size and shape of each particle is discerned from the corresponding scattering pattern. In particular, autocorrelation analysis is used to differentiate between spherical and non-spherical particles, the calculated asphericity factor is used to characterize the morphology of non-spherical particles, and the integrated irradiance is used for particle sizing. We found the fraction of spherical particles decays exponentially with particle size, decreasing from 11% for particles on the order of 1 micrometer to less than 1% for particles over 5 micrometer. The average phase functions of subpopulations of particles, grouped by size and morphology, are determined by averaging their corresponding scattering patterns. The phase functions of spherical and non-spherical atmospheric particles are shown to diverge with increasing size. In addition, the phase function of non-spherical particles is found to vary little as a function of the asphericity factor.

  13. Diffusivity Measurements of Volatile Organics in Levitated Viscous Aerosol Particles

    NASA Astrophysics Data System (ADS)

    Bastelberger, Sandra; Krieger, Ulrich; Luo, Beiping; Peter, Thomas

    2017-04-01

    Field measurements indicating that atmospheric secondary aerosol (SOA) particles can be present in a highly viscous, glassy state have spurred numerous studies addressing low water diffusivities in glassy aerosols, focusing on kinetic limitations to hygroscopic growth and the plasticizing effect of water. Less is known about diffusion limitations of organic molecules and oxidants in viscous matrices and how these might affect atmospheric chemistry and gas-particle phase partitioning of complex mixtures with constituents of different volatility. Often viscosity data has been used to infer diffusivity via the Stokes- Einstein relationship even though strong deviations from this relationship have been observed for matrices of high viscosity. In this study, we provide a quantitative estimate for the diffusivity of a volatile organic in a viscous matrix. Evaporation of single particles generated from an aqueous solution of sucrose and a small quantity of volatile tetraethylene glycol (PEG-4) is investigated in an electrodynamic balance at controlled relative humidity (RH) and temperature conditions, thereby varying the viscosity of the sucrose matrix. The evaporative loss of tetraethylene glycol as determined by Mie resonance spectroscopy is used in conjunction with a diffusion model to retrieve translational diffusion coefficients of tetraethylene glycol. The evaporation of PEG-4 shows a pronounced RH and temperature dependence and is severely depressed for RH 30% corresponding to diffusivities < 10-14 cm2/s at temperatures as high as 15 °C, implying that atmospheric volatile organic compounds (VOC) can be subject to severe diffusion limitations in glassy SOA. Comparison of the experimentally derived diffusivities with viscosity estimates for the ternary system reveals a breakdown of the Stokes-Einstein relationship.

  14. Improved Tandem Measurement Techniques for Aerosol Particle Analysis

    NASA Astrophysics Data System (ADS)

    Rawat, Vivek Kumar

    Non-spherical, chemically inhomogeneous (complex) nanoparticles are encountered in a number of natural and engineered environments, including combustion systems (which produces highly non-spherical aggregates), reactors used in gas-phase materials synthesis of doped or multicomponent materials, and in ambient air. These nanoparticles are often highly diverse in size, composition and shape, and hence require determination of property distribution functions for accurate characterization. This thesis focuses on development of tandem mobility-mass measurement techniques coupled with appropriate data inversion routines to facilitate measurement of two dimensional size-mass distribution functions while correcting for the non-idealities of the instruments. Chapter 1 provides the detailed background and motivation for the studies performed in this thesis. In chapter 2, the development of an inversion routine is described which is employed to determine two dimensional size-mass distribution functions from Differential Mobility Analyzer-Aerosol Particle Mass analyzer tandem measurements. Chapter 3 demonstrates the application of the two dimensional distribution function to compute cumulative mass distribution function and also evaluates the validity of this technique by comparing the calculated total mass concentrations to measured values for a variety of aerosols. In Chapter 4, this tandem measurement technique with the inversion routine is employed to analyze colloidal suspensions. Chapter 5 focuses on application of a transverse modulation ion mobility spectrometer coupled with a mass spectrometer to study the effect of vapor dopants on the mobility shifts of sub 2 nm peptide ion clusters. These mobility shifts are then compared to models based on vapor uptake theories. Finally, in Chapter 6, a conclusion of all the studies performed in this thesis is provided and future avenues of research are discussed.

  15. Measurements of Primary Biogenic Aerosol Particles with an Ultraviolet Aerodynamic Particle Sizer (UVAPS) During AMAZE-08

    NASA Astrophysics Data System (ADS)

    Wollny, A. G.; Garland, R.; Pöschl, U.

    2008-12-01

    Biogenic aerosols are ubiquitous in the Earth's atmosphere and they influence atmospheric chemistry and physics, the biosphere, climate, and public health. They play an important role in the spread of biological organisms and reproductive materials, and they can cause or enhance human, animal, and plant diseases. Moreover, they influence the Earth's energy budget by scattering and absorbing radiation, and they can initiate the formation of clouds and precipitation as cloud condensation and ice nuclei. The composition, abundance, and origin of biogenic aerosol particles and components are, however, still not well understood and poorly quantified. Prominent examples of primary biogenic aerosol particles, which are directly emitted from the biosphere to the atmosphere, are pollen, bacteria, fungal spores, viruses, and fragments of animals and plants. During the AMazonian Aerosol CharacteriZation Experiment (AMAZE-08) a large number of aerosol and gas-phase measurements were taken on a remote site close to Manaus, Brazil, during a period of five weeks in February and March 2008. The presented study is focused on data from an ultraviolet aerodynamic particle sizer (UVAPS, TSI inc.) that has been deployed for the first time in Amazonia. In this instrument, particle counting and aerodynamic sizing over the range of 0.5-20 μm are complemented by the measurement of UV fluorescence at 355 nm (excitation) and 420-575 nm (emission), respectively. Fluorescence at these wavelengths is characteristic for reduced pyridine nucleotides (e.g., NAD(P)H) and for riboflavin, which are specific for living cells. Thus particles exhibiting fluorescence signals can be regarded as 'viable aerosols' or 'fluorescent bioparticles' (FBAP), and their concentration can be considered as lower limit for the actual abundance of primary biogenic aerosol particles. First data analyses show a pronounced peak of FBAP at diameters around 2-3 μm. In this size range the biogenic particle fraction was

  16. Comparison of mineral dust and droplet residuals measured with two single particle aerosol mass spectrometers

    NASA Astrophysics Data System (ADS)

    Wonaschütz, Anna; Ludwig, Wolfgang; Zawadowicz, Maria; Hiranuma, Naruki; Hitzenberger, Regina; Cziczo, Daniel; DeMott, Paul; Möhler, Ottmar

    2017-04-01

    Single Particle mass spectrometers are used to gain information on the chemical composition of individual aerosol particles, aerosol mixing state, and other valuable aerosol characteristics. During the Mass Spectrometry Intercomparison at the Fifth Ice Nucleation (FIN-01) Workshop, the new LAAPTOF single particle aerosol mass spectrometer (AeroMegt GmbH) was conducting simultaneous measurements together with the PALMS (Particle Analysis by Laser Mass Spectrometry) instrument. The aerosol particles were sampled from the AIDA chamber during ice cloud expansion experiments. Samples of mineral dust and ice droplet residuals were measured simultaneously. In this work, three expansion experiments are chosen for a comparison between the two mass spectrometers. A fuzzy clustering routine is used to group the spectra. Cluster centers describing the ensemble of particles are compared. First results show that while differences in the peak heights are likely due to the use of an amplifier in PALMS, cluster centers are comparable.

  17. Aerosol Mass Closure Based On Particle Size Distribution and Aerosol Size Segregated Chemistry Measurements At Mte Cimone (i) (minatroc Project)

    NASA Astrophysics Data System (ADS)

    Putaud, J. P.; van Dingenen, R.; Raes, F.; Facchini, M. C.; Fuzzi, S.; Matta, E.; Decesari, S.

    The MINATROC project is aimed at quantifying the impact of mineral dust on tro- pospheric photochemical cycles and the specific direct effect of secondary aerosol in the presence of mineral dust. This requires a full knowledge of the aerosol physical and chemical properties. During the first MINATROC field experiment (01/06/00- 04/07/00, Mte Cimone, 4411'N, 1042'E, 2165 a.s.l.), a full physical and chemical characterization was performed. A differential mobility particle sizer (DMPS) and an optical particle counter (OPC) were used to monitor the aerosol size distribution in the particle diameter range 6nm - 10 µm. Size segregated aerosol mass distribu- tion and chemical composition were determined from 12hr-integrated 5-stage Berner impactor samples. Gravimetric measurements in dry conditions (RH<20%), ion chro- matography, and a multi-step flash heating thermal method were used to determine aerosol mass, ionic and carbonaceous contents, respectively. Size-segregated aerosol dust content was estimated based on non sea salt calcium concentrations. Sub-micron aerosol ionic composition was also continuously measured using a sampling artifact free wet aerosol denuder - steam jet aerosol collector (WAD-SJAC) combination. The comparison between ammonium nitrate concentrations calculated from the impactor and WAD-SJAC measurements indicate that no significant loss of semi-volatile partic- ulate matter occurred in the impactor. Uncertainties associated with the various mea- surements were assessed. Aerosol mass concentrations derived from chemical analy- sis, and gravimetric and size distribution measurements generally agreed within ex- perimental uncertainties. This indicates that we were able to accurately describe the aerosol chemical composition. The period during which desert dust was observed will be particularly discussed. Variations in the aerosol chemical composition according to various air mass circulation patterns will also be compared to variations in ozone

  18. 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

  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. 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

  1. A Micro Aerosol Sensor for the Measurement of Airborne Ultrafine Particles

    PubMed Central

    Zhang, Chao; Zhu, Rong; Yang, Wenming

    2016-01-01

    Particle number concentration and particle size are the two key parameters used to characterize exposure to airborne nanoparticles or ultrafine particles that have attracted the most attention. This paper proposes a simple micro aerosol sensor for detecting the number concentration and particle size of ultrafine particles with diameters from 50 to 253 nm based on electrical diffusion charging. The sensor is composed of a micro channel and a couple of planar electrodes printed on two circuit boards assembled in parallel, which thus integrate charging, precipitating and measurement elements into one chip, the overall size of which is 98 × 38 × 25 mm3. The experiment results demonstrate that the sensor is useful for measuring monodisperse aerosol particles with number concentrations from 300 to 2.5 × 104 /cm3 and particle sizes from 50 to 253 nm. The aerosol sensor has a simple structure and small size, which is favorable for use in handheld devices. PMID:26999156

  2. A Micro Aerosol Sensor for the Measurement of Airborne Ultrafine Particles.

    PubMed

    Zhang, Chao; Zhu, Rong; Yang, Wenming

    2016-03-18

    Particle number concentration and particle size are the two key parameters used to characterize exposure to airborne nanoparticles or ultrafine particles that have attracted the most attention. This paper proposes a simple micro aerosol sensor for detecting the number concentration and particle size of ultrafine particles with diameters from 50 to 253 nm based on electrical diffusion charging. The sensor is composed of a micro channel and a couple of planar electrodes printed on two circuit boards assembled in parallel, which thus integrate charging, precipitating and measurement elements into one chip, the overall size of which is 98 × 38 × 25 mm³. The experiment results demonstrate that the sensor is useful for measuring monodisperse aerosol particles with number concentrations from 300 to 2.5 × 10⁴ /cm³ and particle sizes from 50 to 253 nm. The aerosol sensor has a simple structure and small size, which is favorable for use in handheld devices.

  3. Glass transition measurements in mixed organic and organic/inorganic aerosol particles

    NASA Astrophysics Data System (ADS)

    Dette, Hans Peter; Qi, Mian; Schröder, David; Godt, Adelheid; Koop, Thomas

    2014-05-01

    The recent proposal of a semi-solid or glassy state of secondary organic aerosol (SOA) particles has sparked intense research in that area. In particular, potential effects of a glassy aerosol state such as incomplete gas-to-particle partitioning of semi-volatile organics, inhibited chemical reactions and water uptake, and the potential to act as heterogeneous ice nuclei have been identified so far. Many of these studies use well-studied proxies for oxidized organics such as sugars or other polyols. There are, however, few measurements on compounds that do exist in atmospheric aerosol particles. Here, we have performed studies on the phase state of organics that actually occur in natural SOA particles arising from the oxidation of alpha-pinene emitted in boreal forests. We have investigated the two marker compounds pinonic acid and 3-methylbutane-1,2,3-tricarboxylic acid (3-MBTCA) and their mixtures. 3-MBCTA was synthesized from methyl isobutyrate and dimethyl maleate in two steps. In order to transfer these substances into a glassy state we have developed a novel aerosol spray drying technique. Dilute solutions of the relevant organics are atomized into aerosol particles which are dried subsequently by diffusion drying. The dried aerosol particles are then recollected in an impactor and studied by means of differential scanning calorimetry (DSC), which provides unambiguous information on the aerosols' phase state, i.e. whether the particles are crystalline or glassy. In the latter case DSC is used to determine the glass transition temperature Tg of the investigated samples. Using the above setup we were able to determine Tg of various mixtures of organic aerosol compounds as a function of their dry mass fraction, thus allowing to infer a relation between Tg and the O:C ratio of the aerosols. Moreover, we also studied the glass transition behavior of mixed organic/inorganic aerosol particles, including the effects of liquid-liquid phase separation upon drying.

  4. Apparatus having reduced background for measuring radiation activity in aerosol particles

    DOEpatents

    Rodgers, John C.; McFarland, Andrew R.; Oritz, Carlos A.; Marlow, William H.

    1992-01-01

    Apparatus having reduced background for measuring radiation activity in aerosol particles. A continuous air monitoring sampler is described for use in detecting the presence of alpha-emitting aerosol particles. An inlet fractionating screen has been demonstrated to remove about 95% of freshly formed radon progeny from the aerosol sample, and approximately 33% of partially aged progeny. Addition of an electrical condenser and a modified dichotomous virtual impactor are expected to produce considerable improvement in these numbers, the goal being to enrich the transuranic (TRU) fraction of the aerosols. This offers the possibility of improving the signal-to-noise ratio for the detected alpha-particle energy spectrum in the region of interest for detecting TRU materials associated with aerosols, thereby enhancing the performance of background-compensation algorithms for improving the quality of alarm signals intended to warn personnel of potentially harmful quantities of TRU materials in the ambient air.

  5. 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.

  6. Comparison between CARIBIC aerosol samples analysed by accelerator-based methods and optical particle counter measurements

    NASA Astrophysics Data System (ADS)

    Martinsson, B. G.; Friberg, J.; Andersson, S. M.; Weigelt, A.; Hermann, M.; Assmann, D.; Voigtländer, J.; Brenninkmeijer, C. A. M.; van Velthoven, P. J. F.; Zahn, A.

    2014-04-01

    Inter-comparison of results from two kinds of aerosol systems in the CARIBIC (Civil Aircraft for the Regular Investigation of the atmosphere Based on an Instrument Container) passenger aircraft based observatory, operating during intercontinental flights at 9-12 km altitude, is presented. Aerosol from the lowermost stratosphere (LMS), the extra-tropical upper troposphere (UT) and the tropical mid troposphere (MT) were investigated. Aerosol particle volume concentration measured with an optical particle counter (OPC) is compared with analytical results of the sum of masses of all major and several minor constituents from aerosol samples collected with an impactor. Analyses were undertaken with accelerator-based methods particle-induced X-ray emission (PIXE) and particle elastic scattering analysis (PESA). Data from 48 flights during one year are used, leading to a total of 106 individual comparisons. The ratios of the particle volume from the OPC and the total mass from the analyses were in 84% within a relatively narrow interval. Data points outside this interval are connected with inlet-related effects in clouds, large variability in aerosol composition, particle size distribution effects and some cases of non-ideal sampling. Overall, the comparison of these two CARIBIC measurements based on vastly different methods show good agreement, implying that the chemical and size information can be combined in studies of the MT/UT/LMS aerosol.

  7. Comparison between CARIBIC Aerosol Samples Analysed by Accelerator-Based Methods and Optical Particle Counter Measurements

    NASA Astrophysics Data System (ADS)

    Martinsson, B. G.; Friberg, J.; Andersson, S. M.; Weigelt, A.; Hermann, M.; Assmann, D.; Voigtländer, J.; Brenninkmeijer, C. A. M.; van Velthoven, P. J. F.; Zahn, A.

    2014-08-01

    Inter-comparison of results from two kinds of aerosol systems in the CARIBIC (Civil Aircraft for the Regular Investigation of the atmosphere Based on a Instrument Container) passenger aircraft based observatory, operating during intercontinental flights at 9-12 km altitude, is presented. Aerosol from the lowermost stratosphere (LMS), the extra-tropical upper troposphere (UT) and the tropical mid troposphere (MT) were investigated. Aerosol particle volume concentration measured with an optical particle counter (OPC) is compared with analytical results of the sum of masses of all major and several minor constituents from aerosol samples collected with an impactor. Analyses were undertaken with the following accelerator-based methods: particle-induced X-ray emission (PIXE) and particle elastic scattering analysis (PESA). Data from 48 flights during 1 year are used, leading to a total of 106 individual comparisons. The ratios of the particle volume from the OPC and the total mass from the analyses were in 84% within a relatively narrow interval. Data points outside this interval are connected with inlet-related effects in clouds, large variability in aerosol composition, particle size distribution effects and some cases of non-ideal sampling. Overall, the comparison of these two CARIBIC measurements based on vastly different methods show good agreement, implying that the chemical and size information can be combined in studies of the MT/UT/LMS aerosol.

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

    NASA Astrophysics Data System (ADS)

    Rozanov, Alexei; Malinina, Elizaveta; Bovensmann, Heinrich; Burrows, John

    2017-04-01

    A crucial role of the stratospheric aerosols for the radiative budget of the Earth's atmosphere and the consequences for the climate change are widely recognized. A reliable knowledge on physical and optical properties of the stratospheric aerosols as well as on their vertical and spatial distributing is a key issue to assure a proper initialization and running conditions for climate models. On a global scale this information can only be gained from space borne measurements. While a series of past, present and future instruments provide extensive date sets of such aerosol characteristics as extinction coefficient or backscattering ratio, information on a size distribution of the stratospheric aerosols is sparse. One of the important sources on vertically and spatially resolved information on the particle size distribution of stratospheric aerosols is provided by space borne measurements of the scattered solar light in limb viewing geometry performed in visible, near-infrared and short-wave infrared spectral ranges. SCIAMACHY (SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY) instrument operated on the European satellite Envisat from 2002 to 2102 was capable of providing spectral information needed to retrieve parameters of aerosol particle size distributions. In this presentation we discuss the retrieval method, present first validation results with SAGE II data and analyze first data sets of stratospheric aerosol particle size distribution parameters obtained from SCIAMACHY limb measurements. The research work was performed in the framework of ROMIC (Role of the middle atmosphere in climate) project.

  9. 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.

  10. Characterization of a Quadrotor Unmanned Aircraft System for Aerosol-Particle-Concentration Measurements.

    PubMed

    Brady, James M; Stokes, M Dale; Bonnardel, Jim; Bertram, Timothy H

    2016-02-02

    High-spatial-resolution, near-surface vertical profiling of atmospheric chemical composition is currently limited by the availability of experimental platforms that can sample in constrained environments. As a result, measurements of near-surface gradients in trace gas and aerosol particle concentrations have been limited to studies conducted from fixed location towers or tethered balloons. Here, we explore the utility of a quadrotor unmanned aircraft system (UAS) as a sampling platform to measure vertical and horizontal concentration gradients of trace gases and aerosol particles at high spatial resolution (1 m) within the mixed layer (0-100 m). A 3D Robotics Iris+ autonomous quadrotor UAS was outfitted with a sensor package consisting of a two-channel aerosol optical particle counter and a CO2 sensor. The UAS demonstrated high precision in both vertical (±0.5 m) and horizontal positions (±1 m), highlighting the potential utility of quadrotor UAS drones for aerosol- and trace-gas measurements within complex terrain, such as the urban environment, forest canopies, and above difficult-to-access areas such as breaking surf. Vertical profiles of aerosol particle number concentrations, acquired from flights conducted along the California coastline, were used to constrain sea-spray aerosol-emission rates from coastal wave breaking.

  11. Decomposition of atmospheric aerosol phase function by particle size and asphericity from measurements of single particle optical scattering patterns

    NASA Astrophysics Data System (ADS)

    Aptowicz, Kevin B.; Pan, Yong-Le; Martin, Sean D.; Fernandez, Elena; Chang, Richard K.; Pinnick, Ronald G.

    2013-12-01

    We demonstrate an experimental approach that provides insight into how particle size and shape affect the scattering phase function of atmospheric aerosol particles. Central to our approach is the design of an apparatus that measures the forward and backward scattering hemispheres (scattering patterns) of individual atmospheric aerosol particles in the coarse mode range. We captured over 30 000 scattering patterns during winter (January 2007) at an urban site in Las Cruces, NM. The size and shape of each particle is discerned from the corresponding scattering pattern. In particular, autocorrelation analysis is used to differentiate between spherical and non-spherical particles, the calculated asphericity factor is used to characterize the morphology of non-spherical particles, and the integrated irradiance is used for particle sizing. We found that the fraction of spherical particles decays exponentially with particle size, decreasing from 11% for particles on the order of 1 μm to less than 1% for particles over 5 μm. The average phase functions of subpopulations of particles, grouped by size and morphology, are determined by averaging their corresponding scattering patterns. The phase functions of spherical and non-spherical atmospheric particles are shown to diverge with increasing size. In addition, the phase function of non-spherical particles is found to vary little as a function of the asphericity factor. Our results support the current remote sensing practice of characterizing atmospheric aerosol particles as a composition of spherical and non-spherical particles with less concern about the diversity of morphology within non-spherical particles. In addition, our results suggest that assuming a constant spherical fraction independent of particle size may not accurately reflect the real morphological distribution of atmospheric aerosol particles.

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

    NASA Technical Reports Server (NTRS)

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

    2012-01-01

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

  13. Investigation of Aerosol Surface Area Estimation from Number and Mass Concentration Measurements: Particle Density Effect

    PubMed Central

    Ku, Bon Ki; Evans, Douglas E.

    2015-01-01

    For nanoparticles with nonspherical morphologies, e.g., open agglomerates or fibrous particles, it is expected that the actual density of agglomerates may be significantly different from the bulk material density. It is further expected that using the material density may upset the relationship between surface area and mass when a method for estimating aerosol surface area from number and mass concentrations (referred to as “Maynard’s estimation method”) is used. Therefore, it is necessary to quantitatively investigate how much the Maynard’s estimation method depends on particle morphology and density. In this study, aerosol surface area estimated from number and mass concentration measurements was evaluated and compared with values from two reference methods: a method proposed by Lall and Friedlander for agglomerates and a mobility based method for compact nonspherical particles using well-defined polydisperse aerosols with known particle densities. Polydisperse silver aerosol particles were generated by an aerosol generation facility. Generated aerosols had a range of morphologies, count median diameters (CMD) between 25 and 50 nm, and geometric standard deviations (GSD) between 1.5 and 1.8. The surface area estimates from number and mass concentration measurements correlated well with the two reference values when gravimetric mass was used. The aerosol surface area estimates from the Maynard’s estimation method were comparable to the reference method for all particle morphologies within the surface area ratios of 3.31 and 0.19 for assumed GSDs 1.5 and 1.8, respectively, when the bulk material density of silver was used. The difference between the Maynard’s estimation method and surface area measured by the reference method for fractal-like agglomerates decreased from 79% to 23% when the measured effective particle density was used, while the difference for nearly spherical particles decreased from 30% to 24%. The results indicate that the use of

  14. Characterizing the impact of urban emissions on regional aerosol particles; airborne measurements during the MEGAPOLI experiment

    NASA Astrophysics Data System (ADS)

    Freney, E. J.; Sellegri, K.; Canonaco, F.; Colomb, A.; Borbon, A.; Michoud, V.; Doussin, J.-F.; Crumeyrolle, S.; Amarouch, N.; Pichon, J.-M.; Prévôt, A. S. H.; Beekmann, M.; Schwarzenböeck, A.

    2013-09-01

    The MEGAPOLI experiment took place in July 2009. The aim of this campaign was to study the aging and reactions of aerosol and gas-phase emissions in the city of Paris. Three ground-based measurement sites and several mobile platforms including instrument equipped vehicles and the ATR-42 aircraft were involved. We present here the variations in particle- and gas-phase species over the city of Paris using a combination of high-time resolution measurements aboard the ATR-42 aircraft. Particle chemical composition was measured using a compact time-of-flight aerosol mass spectrometer (C-ToF-AMS) giving detailed information of the non-refractory submicron aerosol species. The mass concentration of BC, measured by a particle absorption soot photometer (PSAP), was used as a marker to identify the urban pollution plume boundaries. Aerosol mass concentrations and composition were affected by air-mass history, with air masses that spent longest time over land having highest fractions of organic aerosol and higher total mass concentrations. The Paris plume is mainly composed of organic aerosol (OA), black carbon and nitrate aerosol, as well as high concentrations of anthropogenic gas-phase species such as toluene, benzene, and NOx. Using BC and CO as tracers for air-mass dilution, we observe the ratio of ΔOA / ΔBC and ΔOA / ΔCO increase with increasing photochemical age (-log(NOx / NOy). Plotting the equivalent ratios for the Positive Matrix Factorization (PMF) resolved species (LV-OOA, SV-OOA, and HOA) illustrate that the increase in OA is a result of secondary organic aerosol (SOA). Within Paris the changes in the ΔOA / ΔCO are similar to those observed during other studies in Mexico city, Mexico and in New England, USA. Using the measured VOCs species together with recent organic aerosol formation yields we predicted ~ 50% of the measured organics. These airborne measurements during the MEGAPOLI experiment show that urban emissions contribute to the formation of OA

  15. Characterizing the impact of urban emissions on regional aerosol particles: airborne measurements during the MEGAPOLI experiment

    NASA Astrophysics Data System (ADS)

    Freney, E. J.; Sellegri, K.; Canonaco, F.; Colomb, A.; Borbon, A.; Michoud, V.; Doussin, J.-F.; Crumeyrolle, S.; Amarouche, N.; Pichon, J.-M.; Bourianne, T.; Gomes, L.; Prevot, A. S. H.; Beekmann, M.; Schwarzenböeck, A.

    2014-02-01

    The MEGAPOLI (Megacities: Emissions, urban, regional and Global Atmospheric POLlution and climate effects, and Integrated tools for assessment and mitigation) experiment took place in July 2009. The aim of this campaign was to study the aging and reactions of aerosol and gas-phase emissions in the city of Paris. Three ground-based measurement sites and several mobile platforms including instrument equipped vehicles and the ATR-42 aircraft were involved. We present here the variations in particle- and gas-phase species over the city of Paris, using a combination of high-time resolution measurements aboard the ATR-42 aircraft. Particle chemical composition was measured using a compact time-of-flight aerosol mass spectrometer (C-ToF-AMS), giving detailed information on the non-refractory submicron aerosol species. The mass concentration of black carbon (BC), measured by a particle absorption soot photometer (PSAP), was used as a marker to identify the urban pollution plume boundaries. Aerosol mass concentrations and composition were affected by air-mass history, with air masses that spent longest time over land having highest fractions of organic aerosol and higher total mass concentrations. The Paris plume is mainly composed of organic aerosol (OA), BC, and nitrate aerosol, as well as high concentrations of anthropogenic gas-phase species such as toluene, benzene, and NOx. Using BC and CO as tracers for air-mass dilution, we observe the ratio of ΔOA / ΔBC and ΔOA / ΔCO increase with increasing photochemical age (-log(NOx / NOy)). Plotting the equivalent ratios of different organic aerosol species (LV-OOA, SV-OOA, and HOA) illustrate that the increase in OA is a result of secondary organic aerosol (SOA) formation. Within Paris the changes in the ΔOA / ΔCO are similar to those observed during other studies in London, Mexico City, and in New England, USA. Using the measured SOA volatile organic compounds (VOCs) species together with organic aerosol formation

  16. Measurements of aerosol chemistry during new particle formation events at a remote rural mountain site.

    PubMed

    Creamean, Jessie M; Ault, Andrew P; Ten Hoeve, John E; Jacobson, Mark Z; Roberts, Gregory C; Prather, Kimberly A

    2011-10-01

    Determining the major sources of particles that act as cloud condensation nuclei (CCN) represents a critical step in the development of a more fundamental understanding of aerosol impacts on cloud formation and climate. Reported herein are direct measurements of the CCN activity of newly formed ambient particles, measured at a remote rural site in the Sierra Nevada Mountains of Northern California. Nucleation events in the winter of 2009 occurred during two pristine periods following precipitation, with higher gas-phase SO(2) concentrations during the second period, when faster particle growth occurred (7-8 nm/h). Amines, as opposed to ammonia, and sulfate were detected in the particle phase throughout new particle formation (NPF) events, increasing in number as the particles grew to larger sizes. Interestingly, long-range transport of SO(2) from Asia appeared to potentially play a role in NPF during faster particle growth. Understanding the propensity of newly formed particles to act as CCN is critical for predicting the effects of NPF on orographic cloud formation during winter storms along the Sierra Nevada Mountain range. The potential impact of newly formed particles in remote regions needs to be compared with that of transported urban aerosols when evaluating the impact of aerosols on clouds and climate.

  17. Hygroscopic Measurements of Aerosol Particles in Colorado during the Discover AQ Campaign 2014

    NASA Astrophysics Data System (ADS)

    Orozco, D.; Delgado, R.; Espinosa, R.; Martins, J. V.; Hoff, R. M.

    2014-12-01

    In ambient conditions, aerosol particles experience hygroscopic growth due to the influence of relative humidity (RH), scattering more light than when the particles are dry. The quantitative knowledge of the RH effect and its influence on the light scattering and, in particular, on the phase function and polarization of aerosol particles is of substantial importance when comparing ground observations with other optical aerosol measurements such satellite and sunphotometric retrievals of aerosol optical depth and their inversions. In the summer of 2014, the DISCOVER-AQ campaign was held in Colorado, where systematic and concurrent observations of column- integrated surface, and vertically-resolved distributions of aerosols and trace gases relevant to air quality and their evolution during the day were observed. Aerosol optical properties were measured in the UMBC trailer at the city of Golden using a TSI-3563 nephelometer and an in-situ Polarized Imaging Nephelometer (PI-NEPH) designed and built by the LACO group at UMBC. The PI-NEPH measures aerosol phase matrix components in high angular range between 2 and 178 degrees scattering angle at three wavelengths (λ=473, 532 and 671nm). The two measured elements of the phase matrix, intensity (P11) and linear polarization (P12) provide extensive characterization of the scattering properties of the studied aerosol. The scattering coefficient, P11 and P12 were measured under different humidity conditions to obtain the enhancement factor f(RH) and the dependence of P11 and P12 to RH using a humidifier dryer system covering a RH range from 20 to 90%. The ratio between scattering coefficients at high and low humidity in Golden Colorado showed relatively low hygroscopic growth in the aerosol particles f(RH=80%) was 1.27±0.19 for the first three weeks of sampling. According to speciated measurements performed at the UMBC trailer, the predominance of dust and organic aerosols over more hygroscopic nitrate and sulfate in the

  18. USE OF CONTINUOUS MEASUREMENTS OF INTEGRAL AEROSOL PARAMETERS TO ESTIMATE PARTICLE SURFACE AREA

    EPA Science Inventory

    This study was undertaken because of interest in using particle surface area as an indicator for studies of the health effects of particulate matter. First, we wished to determine the integral parameter of the size distribution measured by the electrical aerosol detector. Secon...

  19. Ambient measurement of fluorescent aerosol particles with a WIBS in the Yangtze River Delta of China: potential impacts of combustion-related aerosol particles

    NASA Astrophysics Data System (ADS)

    Yu, Xiawei; Wang, Zhibin; Zhang, Minghui; Kuhn, Uwe; Xie, Zhouqing; Cheng, Yafang; Pöschl, Ulrich; Su, Hang

    2016-09-01

    Fluorescence characteristics of aerosol particles in a polluted atmosphere were studied using a wideband integrated bioaerosol spectrometer (WIBS-4A) in Nanjing, Yangtze River Delta area of China. We observed strong diurnal and day-to-day variations of fluorescent aerosol particles (FAPs). The average number concentrations of FAPs (1-15 µm) detected in the three WIBS measurement channels (FL1: 0.6 cm-3, FL2: 3.4 cm-3, FL3: 2.1 cm-3) were much higher than those observed in forests and rural areas, suggesting that FAPs other than bioaerosols were detected. We found that the number fractions of FAPs were positively correlated with the black carbon mass fraction, especially for the FL1 channel, indicating a large contribution of combustion-related aerosols. To distinguish bioaerosols from combustion-related FAPs, we investigated two classification schemes for use with WIBS data. Our analysis suggests a strong size dependence for the fractional contributions of different types of FAPs. In the FL3 channel, combustion-related particles seem to dominate the 1-2 µm size range while bioaerosols dominate the 2-5 µm range. The number fractions of combustion-related particles and non-combustion-related particles to total aerosol particles were ˜ 11 and ˜ 5 %, respectively.

  20. LOAC (Light Optical Particle Counter): a new small aerosol counter with particle characterization capabilities for surface and airborne measurements

    NASA Astrophysics Data System (ADS)

    Renard, Jean-Baptiste; Berthet, Gwenael; Jégou, Fabrice; Jeannot, Matthieu; Jourdain, Line; Dulac, François; Mallet, Marc; Dupont, Jean-Charles; Thaury, Claire; Tonnelier, Thierry; Verdier, Nicolas; Charpentier, Patrick

    2013-04-01

    The determination of the size distribution of tropospheric and stratospheric aerosols with conventional optical counters is difficult when different natures of particles are present (droplets, soot, mineral dust, secondary organic or mineral particles...). Also, a light and cheap aerosol counter that can be used at ground, onboard drones or launched under all kinds of atmospheric balloons can be very useful during specific events as volcanic plumes, desert dust transport or local pollution episodes. These goals can be achieved thanks to a new generation of aerosol counter, called LOAC (Light Optical Aerosol Counter). The instrument was developed in the frame of a cooperation between French scientific laboratories (CNRS), the Environnement-SA and MeteoModem companies and the French Space Agency (CNES). LOAC is a small optical particle counter/sizer of ~250 grams, having a low electrical power consumption. The measurements are conducted at two scattering angles. The first one, at 12°, is used to determine the aerosol particle concentrations in 19 size classes within a diameter range of 0.3-100 micrometerers. At such an angle close to forward scattering, the signal is much more intense and the measurements are the least sensitive to the particle nature. The second angle is at 60°, where the scattered light is strongly dependent on the particle refractive index and thus on the nature of the aerosols. The ratio of the measurements at the two angles is used to discriminate between the different types of particles dominating the nature of the aerosol particles in the different size classes. The sensor particularly discriminates wet or liquid particles, soil dust and soot. Since 2011, we have operated LOAC in various environments (Arctic, Mediterranean, urban and peri-urban…) under different kinds of balloons including zero pressure stratospheric, tethered, drifting tropospheric, and meteorological sounding balloons. For the last case, the total weight of the gondola

  1. Evaluation of SAGE II and Balloon-Borne Stratospheric Aerosol Measurements: Evaluation of Aerosol Measurements from SAGE II, HALOE, and Balloonborne Optical Particle Counters

    NASA Technical Reports Server (NTRS)

    Hervig, Mark; Deshler, Terry; Moddrea, G. (Technical Monitor)

    2002-01-01

    Stratospheric aerosol measurements from the University of Wyoming balloonborne optical particle counters (OPCs), the Stratospheric Aerosol and Gas Experiment (SAGE) II, and the Halogen Occultation Experiment (HALOE) were compared in the period 1982-2000, when measurements were available. The OPCs measure aerosol size distributions, and HALOE multiwavelength (2.45-5.26 micrometers) extinction measurements can be used to retrieve aerosol size distributions. Aerosol extinctions at the SAGE II wavelengths (0.386-1.02 micrometers) were computed from these size distributions and compared to SAGE II measurements. In addition, surface areas derived from all three experiments were compared. While the overall impression from these results is encouraging, the agreement can change with latitude, altitude, time, and parameter. In the broadest sense, these comparisons fall into two categories: high aerosol loading (volcanic periods) and low aerosol loading (background periods and altitudes above 25 km). When the aerosol amount was low, SAGE II and HALOE extinctions were higher than the OPC estimates, while the SAGE II surface areas were lower than HALOE and the OPCS. Under high loading conditions all three instruments mutually agree to within 50%.

  2. Aerosol Particle Interfacial Thermodynamics and Phase Partitioning Measurements Using Biphasic Microfluidics

    NASA Astrophysics Data System (ADS)

    Dutcher, Cari; Metcalf, Andrew

    2015-03-01

    Secondary organic aerosol particles are nearly ubiquitous in the atmosphere and yet there remain large uncertainties in their formation processes and ambient properties. These particles are complex microenvironments, which can contain multiple interfaces due to internal aqueous-organic phase partitioning and to the external liquid-vapor surface. Interfacial properties affect the ambient aerosol morphology, or internal structure of the particle, which in turn can affect the way a particle interacts with an environment of condensable clusters and organic vapors. To improve our ability to accurately predict ambient aerosol morphology, we must improve our knowledge of aerosol interfaces and their interactions with the ambient environment. Unfortunately, many techniques employed to measure interfacial properties do so in bulk solutions or in the presence of a ternary (e.g. solid) phase. In this talk, a novel method using biphasic microscale flows will be introduced for generating, trapping, and perturbing complex interfaces at atmospherically relevant conditions. These microfluidic experiments utilize high-speed imaging to monitor interfacial phenomena at the microscale and are performed with phase contrast and fluorescence microscopy on a temperature-controlled inverted microscope stage. From these experiments, interfacial thermodynamic properties such as surface or interfacial tension, rheological properties such as interfacial moduli, and kinetic properties such as mass transfer coefficients can be measured or inferred.

  3. The effect of phase partitioning of semivolatile compounds on the measured CCN activity of aerosol particles

    NASA Astrophysics Data System (ADS)

    Romakkaniemi, S.; Jaatinen, A.; Laaksonen, A.; Nenes, A.; Raatikainen, T.

    2013-09-01

    The effect of inorganic semivolatile aerosol compounds on the CCN activity of aerosol particles was studied by using a computational model for a DMT-CCN counter, a cloud parcel model for condensation kinetics and experiments to quantify the modelled results. Concentrations of water vapour and semivolatiles as well as aerosol trajectories in the CCN column were calculated by a computational fluid dynamics model. These trajectories and vapour concentrations were then used as an input for the cloud parcel model to simulate mass transfer kinetics of water and semivolatiles between aerosol particles and the gas phase. Two different questions were studied: (1) how big fraction of semivolatiles is evaporated from particles before activation in the CCN counter? (2) How much the CCN activity can be increased due to condensation of semivolatiles prior to the maximum water supersaturation in the case of high semivolatile concentration in the gas phase? The results show that, to increase the CCN activity of aerosol particles, a very high gas phase concentration (as compared to typical ambient conditions) is needed. We used nitric acid as a test compound. A concentration of several ppb or higher is needed for measurable effect. In the case of particle evaporation, we used ammonium nitrate as a test compound and found that it partially evaporates before maximum supersaturation is reached in the CCN counter, thus causing an underestimation of CCN activity. The effect of evaporation is clearly visible in all supersaturations, leading to an underestimation of the critical dry diameter by 10 to 15 nanometres in the case of ammonium nitrate particles in different supersaturations. This result was also confirmed by measurements in supersaturations between 0.1 and 0.7%.

  4. Aerosol mass spectrometry: particle-vaporizer interactions and their consequences for the measurements

    NASA Astrophysics Data System (ADS)

    Drewnick, F.; Diesch, J.-M.; Faber, P.; Borrmann, S.

    2015-09-01

    The Aerodyne aerosol mass spectrometer (AMS) is a frequently used instrument for on-line measurement of the ambient sub-micron aerosol composition. With the help of calibrations and a number of assumptions on the flash vaporization and electron impact ionization processes, this instrument provides robust quantitative information on various non-refractory ambient aerosol components. However, when measuring close to certain anthropogenic or marine sources of semi-refractory aerosols, several of these assumptions may not be met and measurement results might easily be incorrectly interpreted if not carefully analyzed for unique ions, isotope patterns, and potential slow vaporization associated with semi-refractory species. Here we discuss various aspects of the interaction of aerosol particles with the AMS tungsten vaporizer and the consequences for the measurement results: semi-refractory components - i.e., components that vaporize but do not flash-vaporize at the vaporizer and ionizer temperatures, like metal halides (e.g., chlorides, bromides or iodides of Al, Ba, Cd, Cu, Fe, Hg, K, Na, Pb, Sr, Zn) - can be measured semi-quantitatively despite their relatively slow vaporization from the vaporizer. Even though non-refractory components (e.g., NH4NO3 or (NH4)2SO4) vaporize quickly, under certain conditions their differences in vaporization kinetics can result in undesired biases in ion collection efficiency in thresholded measurements. Chemical reactions with oxygen from the aerosol flow can have an influence on the mass spectra for certain components (e.g., organic species). Finally, chemical reactions of the aerosol with the vaporizer surface can result in additional signals in the mass spectra (e.g., WO2Cl2-related signals from particulate Cl) and in conditioning or contamination of the vaporizer, with potential memory effects influencing the mass spectra of subsequent measurements. Laboratory experiments that investigate these particle-vaporizer interactions are

  5. Real-time measurement of sodium chloride in individual aerosol particles by mass spectrometry

    NASA Technical Reports Server (NTRS)

    Sinha, M. P.; Friedlander, S. K.

    1985-01-01

    The method of particle analysis by mass spectrometry has been applied to the quantitative measurement of sodium chloride in individual particles on a real-time basis. Particles of known masses are individually introduced, in the form of a beam, into a miniature Knudsen cell oven (1600 K). The oven is fabricated from rhenium metal sheet (0.018 mm thick) and is situated in the ion source of a quadrupole mass spectrometer. A particle once inside the oven is trapped and completely volatilized; this overcomes the problem of partial volatilization due to particles bouncing from the filament surface. Individual particles are thermally volatilized and ionized inside the rhenium oven, and produce discrete sodium ion pulses whose intensities are measured with the quadrupole mass spectrometer. An ion pulse width of several milliseconds (4-12 ms) is found for particles in the mass range 1.3 x 10 to the -13th to 5.4 x 10 to the -11th g. The sodium ion intensity is found to be proportional to the particle mass to the 0.86-power. The intensity distribution for monodisperse aerosol particles possesses a geometric standard deviation of 1.09, showing that the method can be used for the determination of the mass distribution function with good resolution in a polydisperse aerosol.

  6. Urban organic aerosols measured by single particle mass spectrometry in the megacity of London

    NASA Astrophysics Data System (ADS)

    Dall'Osto, M.; Harrison, R. M.

    2011-02-01

    During the month of October 2006, as part of the REPARTEE-I experiment (Regent's Park and Tower Environmental Experiment) an Aerosol Time-Of-Flight Mass Spectrometer (ATOFMS) was deployed at an urban background location in the city of London, UK. Fifteen particle types were classified, some of which were accompanied by Aerosol Mass Spectrometer (AMS) quantitative aerosol mass loading measurements (Dall'Osto et al., 2009a, b). In this manuscript the origins and properties of four particle types associated with locally generated aerosols, independent of the air mass type advected into London, are examined. One particle type, originating from lubricating oil (referred to as Ca-EC), was associated with morning rush hour traffic emissions. A second particle type, composed of both inorganic and organic species (called Na-EC-OC), was found enhanced in particle number concentration during evening time periods, and is likely to originate from a source operating at this time of day, or more probably from condensation of semi-volatile species, and contains both primary and secondary components. A third class, internally mixed with organic carbon and sulphate (called OC), was found to spike both in the morning and evenings. The fourth class (SOA-PAH) exhibited maximum frequency during the warmest part of the day, and a number of factors point towards secondary production from traffic-related volatile aromatic compounds. Single particle mass spectra of this particle type showed an oxidized polycyclic aromatic compound signature. Finally, a comparison of ATOFMS particle class data is made with factors obtained by Positive Matrix Factorization from AMS data.. Both the Ca-EC and OC particle types correlate with the AMS HOA primary organic fraction (R2 = 0.65 and 0.50 respectively), and Na-EC-OC, but not SOA-PAH, which correlates weakly with the AMS OOA secondary organic aerosol factor (R2 = 0.35). A detailed analysis was conducted to identify ATOFMS particle type(s) representative

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

    NASA Astrophysics Data System (ADS)

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

    1995-10-01

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

  8. The Arctic polar stratospheric cloud aerosol - Aircraft measurements of reactive nitrogen, total water, and particles

    NASA Technical Reports Server (NTRS)

    Kawa, S. R.; Fahey, D. W.; Kelly, K. K.; Dye, J. E.; Baumgardner, D.; Gandrud, B. W.; Loewenstein, M.; Ferry, G. V.; Chan, K. R.

    1992-01-01

    In situ aircraft measurements in the lower stratosphere are used to investigate the reactive nitrogen, NO(y), total water, and particle components of the polar stratospheric cloud (PSC) aerosol in the Arctic. The results are compared to findings from the Antarctic derived using similar measurements and interpretive techniques. The Arctic data show that particle volume well above background values is present at temperatures above the frostpoint, confirming the result from the Antarctic that the observed PSCs are not water ice particles. NO(y) measurements inside a PSC are enhanced above ambient values consistent with anisokinetic sampling of particles containing NO(y). In the Arctic data over long segments of several flights, calculations show saturation with respect to nitric acid trihydrate without significant PSC particle growth above background.

  9. A Single Particle Soot Photometer for the Measurement of Aerosol Black Carbon

    NASA Astrophysics Data System (ADS)

    Kok, G. L.; Baumgardner, D.; Spuler, S.

    2002-12-01

    A Single Particle Soot Photometer (SP2) has been developed for the measurement of black carbon mass in single particles. The analytical technique is the incandescence of light absorbing particles. An aerosol stream is directed intra-cavity across the beam of a Nd:YAG laser where the laser intensity is in excess of 1 MW/cm2. Non-light absorbing particles only scatter light but particles containing black carbon absorb sufficient energy to heat and incandesce as they vaporize. Four optical detectors are used to measure the scattered and incandescence radiation from the particles. One measures the scattered, 1064 nm radiation while the other three detectors measure the light of incandescence over different wavelength regions. The ratio of intensities at the different wavelengths yields the temperature at which the particle incandesced whereas the absolute intensity is proportional to the carbon mass. The minimum size of non-incandescing particles that can be measured is approximately 100 nm and for incandescing particles it is 80 nm. Data will be presented on the operation of the instrumentation and examples of ambient measurements of black carbon.

  10. Origin and impact of particle-to-particle variations in composition measurements with the nano-aerosol mass spectrometer.

    PubMed

    Klems, Joseph P; Johnston, Murray V

    2013-09-01

    In the nano-aerosol mass spectrometer, individual particles in the 10-30 nm size range are trapped and irradiated with a high pulse energy laser beam. The laser pulse generates a plasma that disintegrates the particle into atomic ions, from which the elemental composition is determined. Particle-to-particle variations among the mass spectra are shown to arise from plasma energetics: Low ionization energy species are enhanced in some spectra while high ionization energy species are enhanced in others. These variations also limit the accuracy and precision of elemental analysis, with higher deviations generally observed when low ionization energy species are dominant in the mass spectrum. For standard datasets generated from nominally identical particles, it is shown that that the error associated with composition measurement is random and that averaging the spectra from a few tens of particles is sufficient for measuring the mole fractions of common elements to within about 10% of the expected value. Averaging a greater number of particles offers limited improvement of the measurement precision but has the deleterious effect of degrading the measurement time-resolution, which is given by the time needed to obtain the required number of particle spectra for averaging. An internally mixed ambient particle dataset was found to give a similar result to the standard datasets, that is, the measured elemental composition converged to the average value after a few tens of particles were averaged.

  11. Aerosol mass spectrometry: particle-vaporizer interactions and their consequences for the measurements

    NASA Astrophysics Data System (ADS)

    Drewnick, F.; Diesch, J.-M.; Faber, P.; Borrmann, S.

    2015-04-01

    The Aerodyne Aerosol Mass Spectrometer (AMS) is a frequently used instrument for on-line measurement of the ambient sub-micron aerosol composition. With the help of calibrations and a number of assumptions on the flash vaporization and electron impact ionization processes this instrument provides robust quantitative information on various ambient aerosol components. However, when measuring close to certain anthropogenic sources or in marine environments, several of these assumptions may not be met and measurement results might easily be misinterpreted. Here we discuss various aspects of the interaction of aerosol particles with the AMS tungsten vaporizer and the consequences for the measurement results: semi-refractory components, i.e. components that vaporize but do not flash vaporize at the vaporizer and ionizer temperatures, like metal halides (e.g. chlorides, bromides or iodides of Al, Ba, Cd, Cu, Fe, Hg, K, Na, Pb, Sr, Zn) can be measured semi-quantitatively despite their relatively slow vaporization from the vaporizer. Even though non-refractory components (e.g. NH4NO3 or (NH4)2SO4) vaporize quickly, their differences in vaporization kinetics can result in undesired biases in ion collection efficiency in the measurements. Chemical reactions with water vapor and oxygen from the aerosol flow can have an influence on the mass spectra for certain components (e.g. NH4NO3, (NH4)2SO4, organic species). Finally, chemical reactions of the aerosol with the vaporizer surface can result in additional signals in the mass spectra (e.g. WO2C2-related signals from particulate Cl) and in conditioning or contamination of the vaporizer with potential memory effects influencing the mass spectra of subsequent measurements. Laboratory experiments that investigate these particle-vaporizer interactions are presented and are discussed together with field results showing that measurements of typical continental or urban aerosols are not significantly affected while laboratory

  12. Airborne measurements of cloud forming nuclei and aerosol particles at Kennedy Space Center, Florida

    NASA Technical Reports Server (NTRS)

    Radke, L. F.; Langer, G.; Hindman, E. E., II

    1978-01-01

    Results of airborne measurements of the sizes and concentrations of aerosol particles, ice nuclei, and cloud condensation nuclei that were taken at Kennedy Space Center, Florida, are presented along with a detailed description of the instrumentation and measuring capabilities of the University of Washington airborne measuring facility (Douglas B-23). Airborne measurements made at Ft. Collins, Colorado, and Little Rock, Arkansas, during the ferry of the B-23 are presented. The particle concentrations differed significantly between the clean air over Ft. Collins and the hazy air over Little Rock and Kennedy Space Center. The concentrations of cloud condensation nuclei over Kennedy Space Center were typical of polluted eastern seaboard air. Three different instruments were used to measure ice nuclei: one used filters to collect the particles, and the others used optical and acoustical methods to detect ice crystals grown in portable cloud chambers. A comparison of the ice nucleus counts, which are in good agreement, is presented.

  13. Spatio-temporal aerosol particle distributions in the UT/LMS measured by the IAGOS-CARIBIC Observatory

    NASA Astrophysics Data System (ADS)

    Assmann, Denise; Hermann, Markus; Weigelt, Andreas; Martinsson, Bengt; Brenninkmeijer, Carl; Rauthe-Schöch, Armin; van Velthoven, Peter; Bönisch, Harald; Zahn, Andreas

    2017-04-01

    Submicrometer aerosol particles in the upper troposphere and lowermost stratosphere (UT/LMS) influence the Earth`s radiation budget directly and, more important, indirectly, by acting as cloud condensation nuclei and by changing trace gas concentrations through heterogeneous chemical processes. Since 1997, regular in situ UT/LMS aerosol particle measurements have been conducted by the Leibniz Institute for Tropospheric Research, Leipzig, Germany and the University of Lund, Sweden, using the the CARIBIC (now IAGOS-CARIBIC) observatory (www.caribic-atmospheric.com) onboard a passenger aircraft. Submicrometer aerosol particle number concentrations and the aerosol particle size distribution are measured using three condensation particle counters and one optical particle size spectrometer. Moreover, particle elemental composition is determined using an aerosol impactor sampler and post-flight ion beam analysis (PIXE, PESA) of the samples in the laboratory. Based on this unique data set, including meteorological analysis, we present representative spatio-temporal distributions of particle number, surface, volume and elemental concentrations in an altitude of 8-12 km covering a large fraction of the northern hemisphere. We discuss the measured values in the different size regimes with respect to sources and sinks in different regions. Additionally, we calculated highly resolved latitudinal and longitudinal cross sections of the particle number size distribution, probability density functions and trends in particle number concentrations, but also in elemental composition, determined from our regular measurements over more than a decade. Moreover, we generated seasonal contour plots for particle number concentrations, the potential temperature, and the equivalent latitude. The results are interpreted with respect to aerosol microphysics and transport using CARIBIC trace gas data like ozone and water vapour. The influence of clouds in the troposphere and the different

  14. Determination of dust aerosol particle size at Gale Crater using REMS UVS and Mastcam measurements

    NASA Astrophysics Data System (ADS)

    Vicente-Retortillo, Álvaro; Martínez, Germán. M.; Renno, Nilton O.; Lemmon, Mark T.; de la Torre-Juárez, Manuel

    2017-04-01

    We calculate the seasonal and interannual variation in dust aerosol particle size above Gale Crater during the first 1413 Martian solar days (sols = 24.6 h) of the Mars Science Laboratory mission. Measurements of UV radiation made by the Rover Environmental Monitoring Station in combination with atmospheric opacities retrieved from the Mastcam instrument are used for the calculations. Our results indicate that the dust effective radius varies significantly with season, ranging from 0.6 μm during the low opacity season (Ls = 60°-140°) to 2 μm during the high opacity season (Ls = 180°-360°). Our results suggest that Gale Crater is affected by dust events of high aerosol content originated at various distances from it. Our results improve the accuracy of estimations of ultraviolet radiation fluxes at the Martian surface. Moreover, our results have important implications because the lifetime of suspended dust and its ability to nucleate clouds are affected by particle size.

  15. 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

  16. Measurements of aerosol particles in the Škocjan Caves, Slovenia.

    PubMed

    Grgić, Irena; Iskra, Ivan; Podkrajšek, Boštjan; Gerjevič, Vanja Debevec

    2014-02-01

    For the first time, continuous aerosol measurements were performed in the Škocjan Caves, one of the most important cave systems in the world, and listed by UNESCO as a natural and cultural world heritage site since 1986. Measurements of PM10 were performed during three different periods: (1) in December 2011, the average background concentration was found to be about 4 μg m(-3); (2) in June 2012, a higher concentration was measured (8 μg m(-3)); and (3) from 8 to 20 August 2012, the highest concentration of 15.3 μg m(-3) was measured. Based on the PM10 measurement results, and as compared to similar measurements outside the cave, it can be hypothesized that the increase in the cave's aerosol concentration during the summer was connected to both the higher number of visitors and the polluted atmospheric air entering the cave upon entering of the cave system. Additional measurement of nanoparticles with scanning mobility particle sizer spectrometer (size between 14.1 and 710.5 nm) confirmed these findings; during the summer period, a severe raise in the total aerosol concentration of 30-50 times was found when groups of visitors entered the cave. Our results on nanoparticles demonstrated that we were able to detect very small changes and variations in aerosol concentration inside the cave. To our knowledge, these are the first results on nanoaerosol measurements in a cave, and we believe that such measurements may lead to the implementation of better protection of delicate cave systems.

  17. A new approach to characterise pharmaceutical aerosols: measurement of aerosol from a single dose aqueous inhaler with an optical particle counter.

    PubMed

    Kuhli, Maren; Weiss, Maximilian; Steckel, Hartwig

    2010-01-31

    An in-line sampling system with dilution units for aqueous droplet aerosols from single dose inhalers (Berodual Respimat, Boehringer Ingelheim Pharma GmbH & Co. KG, Germany) for an optical particle counter is described. The device has been designed to interface with a white light aerosol spectrometer (welas digital 2100, Palas GmbH, Germany) that allows the time-resolved measurement of highly concentrated aerosols. Performance of the sampling system with regard to the measured particle size distribution (PSD) is compared to Next Generation Impactor (NGI) and to laser diffraction measurements (Sympatec Inhaler and open bench). Optimal settings of the sampling system lead to PSDs that correspond well to those measured by the evaporation minimising NGI approach (15 L/min, cooled) and laser diffraction. The better accuracy of the new dilution unit in presence of an additional aerosol sampling filter in comparison to a previously described aerosol sampling system is shown for different settings of the sampling system. This allows a more precise quantification of the delivered drug amount which is also well correlated to the aerosol volume measured by the welas system. In addition, using time-resolved welas measurements provides insight into droplet size, evaporation and size changes of aerosol clouds delivered by liquid inhalers. Copyright 2009 Elsevier B.V. All rights reserved.

  18. Measurements of the absorption and scattering coefficients of aerosol particles in suburb of Nanjing (China)

    NASA Astrophysics Data System (ADS)

    Yin, Yan; Chen, Yu; Wang, Weiwei; Yan, Jiade; Qian, Ling; Tong, Yaoqing; Lin, Zhenyi

    2008-08-01

    The absorption and scattering coefficients of atmospheric aerosols were continuously measured with a Photoacoustic Soot Spectrometer (PASS, DMT Inc. USA) at a suburb site of Nanjing, one of the regions experiencing rapid industrialization in China. The measurements were carried out during autumn and winter 2007. A preliminary analysis of the data shows that, the scattering coefficient, Bscat, is two to ten times larger than the absorption coefficient, Babs, implying that the aerosols formed/emitted in this area are more scattering than previous assumed, and can be more important in cooling the Earth-atmosphere system. The results also indicate that the absolute values of both parameters are very much dependent on the meteorological conditions, such as wind speed and direction, fog, rain, etc. as well as the time of the day. Higher values often appear at nighttimes when wind is weak, especially when a temperature inverse layer is present near the surface. Higher values of Bscat and Babs were also observed under hazy and foggy weather conditions or when wind is blown from east, where a large industrial zone is located. Simultaneous measurements of the number concentrations, chemical compositions, and size distributions of aerosol particles are used to explain the characteristics of the changes in Bscat and Babs.

  19. Hygrosopicity measurements of aerosol particles in the San Joaquin Valley, CA, Baltimore, MD, and Golden, CO

    NASA Astrophysics Data System (ADS)

    Orozco, Daniel; Beyersdorf, A. J.; Ziemba, L. D.; Berkoff, T.; Zhang, Q.; Delgado, R.; Hennigan, C. J.; Thornhill, K. L.; Young, D. E.; Parworth, C.; Kim, H.; Hoff, R. M.

    2016-06-01

    Aerosol hygroscopicity was investigated using a novel dryer-humidifier system, coupled to a TSI-3563 nephelometer, to obtain the light scattering coefficient (σscat) as a function of relative humidity (RH) in hydration and dehydration modes. The measurements were performed in Porterville, CA (10 January to 6 February 2013), Baltimore, MD (3-30 July 2013), and Golden, CO (12 July to 10 August 2014). Observations in Porterville and Golden were part of the NASA-sponsored Deriving Information on Surface Conditions from Column and Vertically Resolved Observations Relevant to Air Quality project. The measured σscat under varying RH in the three sites was combined with ground aerosol extinction, PM2.5 mass concentrations, and particle composition measurements and compared with airborne observations performed during campaigns. The enhancement factor, f(RH), defined as the ratio of σscat(RH) at a certain RH divided by σscat at a dry value, was used to evaluate the aerosol hygroscopicity. Particles in Porterville showed low average f(RH = 80%) (1.42) which was attributed to the high carbonaceous loading in the region where residential biomass burning and traffic emissions contribute heavily to air pollution. In Baltimore, the high average f(RH = 80%) (2.06) was attributed to the large contribution of SO42- in the region. The lowest water uptake was observed in Golden, with an average f(RH = 80%) = 1.24 where organic carbon dominated the particle loading. Different empirical fits were evaluated using the f(RH) data. The widely used Kasten (gamma) model was found least satisfactory, as it overestimates f(RH) for RH < 75%. A better empirical fit with two power law curve fitting parameters c and k was found to replicate f(RH) accurately from the three sites. The relationship between the organic carbon mass and the species that are affected by RH and f(RH) was also studied and categorized.

  20. A recirculation aerosol wind tunnel for evaluating aerosol samplers and measuring particle penetration through protective clothing materials.

    PubMed

    Jaques, Peter A; Hsiao, Ta-Chih; Gao, Pengfei

    2011-08-01

    A recirculation aerosol wind tunnel was designed to maintain a uniform airflow and stable aerosol size distribution for evaluating aerosol sampler performance and determining particle penetration through protective clothing materials. The oval-shaped wind tunnel was designed to be small enough to fit onto a lab bench, have optimized dimensions for uniformity in wind speed and particle size distributions, sufficient mixing for even distribution of particles, and minimum particle losses. Performance evaluation demonstrates a relatively high level of spatial uniformity, with a coefficient of variation of 1.5-6.2% for wind velocities between 0.4 and 2.8 m s(-1) and, in this range, 0.8-8.5% for particles between 50 and 450 nm. Aerosol concentration stabilized within the first 5-20 min with, approximately, a count median diameter of 135 nm and geometric standard deviation of 2.20. Negligible agglomerate growth and particle loss are suggested. The recirculation design appears to result in unique features as needed for our research.

  1. Measurements of isoprene-derived organosulfates in ambient aerosols by aerosol time-of-flight mass spectrometry - part 1: single particle atmospheric observations in Atlanta.

    PubMed

    Hatch, Lindsay E; Creamean, Jessie M; Ault, Andrew P; Surratt, Jason D; Chan, Man Nin; Seinfeld, John H; Edgerton, Eric S; Su, Yongxuan; Prather, Kimberly A

    2011-06-15

    Organosulfate species have recently been identified as a potentially significant class of secondary organic aerosol (SOA) species, yet little is known about their behavior in the atmosphere. In this work, organosulfates were observed in individual ambient aerosols using single particle mass spectrometry in Atlanta, GA during the 2002 Aerosol Nucleation and Characterization Experiment (ANARChE) and the 2008 August Mini-Intensive Gas and Aerosol Study (AMIGAS). Organosulfates derived from biogenically produced isoprene were detected as deprotonated molecular ions in negative-ion spectra measured by aerosol time-of-flight mass spectrometry; comparison to high-resolution mass spectrometry data obtained from filter samples corroborated the peak assignments. The size-resolved chemical composition measurements revealed that organosulfate species were mostly detected in submicrometer aerosols and across a range of aerosols from different sources, consistent with secondary reaction products. Detection of organosulfates in a large fraction of negative-ion ambient spectra - ca. 90-95% during ANARChE and ~65% of submicrometer particles in AMIGAS - highlights the ubiquity of organosulfate species in the ambient aerosols of biogenically influenced urban environments.

  2. Hygroscopic growth of atmospheric aerosol particles based on active remote sensing and radiosounding measurements

    NASA Astrophysics Data System (ADS)

    Granados-Muñoz, M. J.; Navas-Guzmán, F.; Bravo-Aranda, J. A.; Guerrero-Rascado, J. L.; Lyamani, H.; Valenzuela, A.; Titos, G.; Fernández-Gálvez, J.; Alados-Arboledas, L.

    2014-10-01

    A new methodology based on combining active and passive remote sensing and simultaneous and collocated radiosounding data to study the aerosol hygroscopic growth effects on the particle optical and microphysical properties is presented. The identification of hygroscopic growth situations combines the analysis of multiespectral aerosol particle backscatter coefficient and particle linear depolarization ratio with thermodynamic profiling of the atmospheric column. We analysed the hygroscopic growth effects on aerosol properties, namely the aerosol particle backscatter coefficient and the volume concentration profiles, using data gathered at Granada EARLINET station. Two study cases, corresponding to different aerosol loads and different aerosol types, are used for illustrating the potential of this methodology. Values of the aerosol particle backscatter coefficient enhancement factors range from 2.10 ± 0.06 to 3.90 ± 0.03, being similar to those previously reported in the literature. Differences in the enhancement factor are directly linked to the composition of the atmospheric aerosol. The largest value of the aerosol particle backscatter coefficient enhancement factor corresponds to the presence of sulphate and marine particles that are more affected by hygroscopic growth. On the contrary, the lowest value of the enhancement factor corresponds to an aerosol mixture containing sulphates and slight traces of mineral dust. The Hänel parameterization is applied to these case studies, obtaining results within the range of values reported in previous studies, with values of the γ exponent of 0.56 ± 0.01 (for anthropogenic particles slightly influenced by mineral dust) and 1.07 ± 0.01 (for the situation dominated by anthropogenic particles), showing the convenience of this remote sensing approach for the study of hygroscopic effects of the atmospheric aerosol under ambient unperturbed conditions. For the first time, the retrieval of the volume concentration profiles

  3. [Factors influencing particle measurement of aerosols and their retention in the lung].

    PubMed

    Le Bouffant, L

    1977-01-01

    The dimensional characteristics of the particles of an aerosol depend on the means used for producing them. Mechanical spray and ultrasonic dispersion give polydispersed particles. On the other hand, centrifugal atomization produces a monodispersed aerosol. Particle retention in the lung system depends on the particle diameter. In addition, retention varies according to the respiratory characteristics: it is minimal for about 15 inspirations per minute. Using iron-59 labeled particles, it was shown that the degree of retention varies considerably from one individual to the other and accessibility to the depths of the lungs is decreased under the effect of certain lesions. Bronchial retention appears to be increased in smokers.

  4. A Method for Measuring the Density of Irregularly Shaped Aerosol Particles Such as Pollen

    NASA Astrophysics Data System (ADS)

    van Hout, R.; Katz, J.

    2003-12-01

    Prediction of the long distance dispersal of (biological) aerosol particles, such as pollen, in the atmosphere is of great importance in pollution control and allergy studies. The particle parameters affecting dispersal include size, shape and density. In this work a simple method has been tested and implemented for measuring the density of aerosols without prior knowledge of their size and shape. The method is based on measurement of the settling velocity of particles in two fluids with different density and viscosity at low Reynolds numbers (Stokes flow). Consequently, the settling velocity is proportional to the particle size and density. For two statistically similar samples of particles, based on pdf of equivalent projected area diameter, the pdf of the particle settling velocity was measured in two fluids with different density and viscosity (Dow Corning 200 fluid). For known fluid properties, the resulting particle density is then proportional to the ratio of the settling velocities in the two fluids. The method was used to determine the density of corn (Zea Mays) pollen. The pollen settling velocity was measured in a square settling chamber (5x5x45cm) using in-line digital holography that allows in-focus tracking of the pollen in a 3-D sample volume. Additional advantages of in-line digital holography are its simple setup and the possibility of recording holographic movies. The measured mean corn pollen density was 1119.3 kg/m3 with an absolute error of 45.2 kg/m3. Pdf's of size distributions (based on projected areas) of corn pollen were determined using optical microscopy and Scanning Electron Microscopy (SEM). These observations were performed with pollen immersed in both Dow Corning 200 fluids as well as in a dry state. No change in size and shape were observed. However when immersed in water, the corn pollen grew and became nearly spherical. Thus, for a known pollen density and size distribution, Stokes' Law for a sphere could be used to predict the

  5. 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

  6. Measurement of Aerosol and Cloud Particles with PACS and HARP Hyperangular Imaging Polarimeters

    NASA Astrophysics Data System (ADS)

    Martins, J.; Fernandez-Borda, R.; Remer, L. A.; Sparr, L.; Buczkowski, S.; Munchak, L. A.

    2013-12-01

    PACS is new hyper-angular imaging polarimeter for aeorosol and cloud measurerents designed to meet the requirements of the proposed ACE decadal survey mission. The full PACS system consists of three wide field of view (110deg cross track) telescopes covering the UV, VNIR, and SWIR spectral ranges with angular coverage between +55 deg forward to -55deg backwards. The angular density can be selected to cover up to 100 different viewing angles at selected wavelengths. PACS_VNIR is a prototype airborne instrument designed to demonstrate PACS capability by deploying just one of the three wavelength modules of the full PACS. With wavelengths at 470, 550, 675, 760 and 875nm, PACS_VNIR flew for the first time during the PODEX experiment in January/February 2013 aboard the NASA ER-2 aircraft. PACS SWIR (1.64, 1.88, 2.1, and 2.25um) is currently under construction and should be operational in the lab by Fall/2013. PACS_ UV has been fully designed, but is not yet under construction. During the PODEX flights PACS_VNIR collected data for aerosol and clouds over variable surface types including, water, vegetation, urban areas, and snow. The data is currently being calibrated, geolocated and prepared for the inversion of geophysical parameters including water cloud size distribution and aerosol microphysical parameters. The large density of angles in PACS allows for the characterization of cloudbow features in relatively high spatial resolution in a pixel to pixel basis. This avoids the need for assumptions of cloud homogeneity over any distance. The hyperangle capability also allows detailed observation of cloud ice particles, surface characterization, and optimum selection of the number of angles desired for aerosol retrievals. The aerosol and cloud retrieval algorithms under development for the retrieval of particle microphysical properties from the PACS data will be discussed in this presentation. As an extension of the PACS concept we are currently developing the HARP (Hyper

  7. Evaluating the applicability of a semi-continuous aerosol sampler to measure Asian dust particles.

    PubMed

    Son, Se-Chang; Park, Seung Shik

    2015-03-01

    A Korean prototype semi-continuous aerosol sampler was used to measure Asian dust particles. During two dust-storm periods, concentrations of crustal and trace elements were significantly enriched. Dust storms are one of the most significant natural sources of air pollution in East Asia. The present study aimed to evaluate use of a Korean semi-continuous aerosol sampler (K-SAS) in observation of mineral dust particles during dust storm events. Aerosol slurry samples were collected at 60 min intervals using the K-SAS, which was operated at a sampling flow rate of 16.7 L min(-1) through a PM10 cyclone inlet. The measurements were made during dust storm events at an urban site, Gwangju in Korea, between April 30 and May 5, 2011. The K-SAS uses particle growth technology as a means of collecting atmospheric aerosol particles. Concentrations of 16 elements (Al, Fe, Mn, Ca, K, Cu, Zn, Pb, Cd, Cr, Ti, V, Ni, Co, As, and Se) were determined off-line in the collected slurry samples by inductively coupled plasma-mass spectrometry (ICP-MS). The sampling periods were classified into two types, based on the source regions of the dust storms and the transport pathways of the air masses reaching the sampling site. The first period "A" was associated with dust particles with high Ca content, originating from the Gobi desert regions of northern China and southern Mongolia. The second period "B" was associated with dust particles with low Ca content, originating from northeastern Chinese sandy deserts. The results from the K-SAS indicated noticeable differences in concentrations of crustal and trace elements in the two sampling periods, as a result of differences in the source regions of the dust storms, the air mass transport pathways, and the impact of smoke from forest fires. The concentrations of the crustal (Al, Ca, Ti, Mn, and Fe) and anthropogenic trace elements (Vi, Ni, Cu, Zn, As, Se, and Pb) were enriched significantly during the two dust storm periods. However, the

  8. Measurements of extinction by aerosol particles in the near-infrared using continuous wave cavity ring-down spectroscopy.

    PubMed

    Mellon, Daniel; King, Simon J; Kim, Jin; Reid, Jonathan P; Orr-Ewing, Andrew J

    2011-02-10

    Cavity ring-down spectroscopy using a fiber-coupled continuous wave distributed feedback laser at a wavelength of 1520 nm has been used to measure extinction of light by samples of nearly monodisperse aerosol particles <1 μm in diameter. A model is tested for the analysis of the sample extinction that is based on the Poisson statistics of the number of particles within the intracavity laser beam: variances of measured extinction are used to derive values of the scattering cross section for size-selected aerosol particles, without need for knowledge of the particle number density or sample length. Experimental parameters that influence the performance of the CRD system and the application and limitations of the statistical model are examined in detail. Determinations are reported of the scattering cross sections for polystyrene spheres (PSSs), sodium chloride, and ammonium sulfate, and, for particles greater than 500 nm in diameter, are shown to be in agreement with the corresponding values calculated using Mie theory or Discrete Dipole Approximation methods. For smaller particles, the experimentally derived values of the scattering cross section are larger than the theoretical predictions, and transmission of a small fraction of larger particles into the cavity is argued to be responsible for this discrepancy. The effects of cubic structure on the determination of optical extinction efficiencies of sodium chloride aerosol particles are examined. Values are reported for the real components of the refractive indices at 1520 nm of PSS, sodium chloride, and ammonium sulfate aerosol particles.

  9. Measurements of Ultra-fine and Fine Aerosol Particles over Siberia: Large-scale Airborne Campaigns

    NASA Astrophysics Data System (ADS)

    Arshinov, Mikhail; Paris, Jean-Daniel; Stohl, Andreas; Belan, Boris; Ciais, Philippe; Nédélec, Philippe

    2010-05-01

    In this paper we discuss the results of in-situ measurements of ultra-fine and fine aerosol particles carried out in the troposphere from 500 to 7000 m in the framework of several International and Russian State Projects. Number concentrations of ultra-fine and fine aerosol particles measured during intensive airborne campaigns are presented. Measurements carried over a great part of Siberia were focused on particles with diameters from 3 to 21 nm to study new particle formation in the free/upper troposphere over middle and high latitudes of Asia, which is the most unexplored region of the Northern Hemisphere. Joint International airborne surveys were performed along the following routes: Novosibirsk-Salekhard-Khatanga-Chokurdakh-Pevek-Yakutsk-Mirny-Novosibirsk (YAK-AEROSIB/PLARCAT2008 Project) and Novosibirsk-Mirny-Yakutsk-Lensk-Bratsk-Novosibirsk (YAK-AEROSIB Project). The flights over Lake Baikal was conducted under Russian State contract. Concentrations of ultra-fine and fine particles were measured with automated diffusion battery (ADB, designed by ICKC SB RAS, Novosibirsk, Russia) modified for airborne applications. The airborne ADB coupled with CPC has an additional aspiration unit to compensate ambient pressure and changing flow rate. It enabled to classify nanoparticles in three size ranges: 3-6 nm, 6-21 nm, and 21-200 nm. To identify new particle formation events we used similar specific criteria as Young et al. (2007): (1) N3-6nm >10 cm-3, (2) R1=N3-6/N621 >1 and R2=N321/N21200 >0.5. So when one of the ratios R1 or R2 tends to decrease to the above limits the new particle formation is weakened. It is very important to notice that space scale where new particle formation was observed is rather large. All the events revealed in the FT occurred under clean air conditions (low CO mixing ratios). Measurements carried out in the atmospheric boundary layer over Baikal Lake did not reveal any event of new particle formation. Concentrations of ultra

  10. Balloon borne measurements of aerosol and cloud particles over Japan during PACDEX

    NASA Astrophysics Data System (ADS)

    Sakai, T.; Orikasa, N.; Nagai, T.; Murakami, M.; Tajiri, T.; Saito, A.; Yamashita, K.

    2007-12-01

    This paper presents the preliminary result of the balloon borne measurements of the aerosol and cloud microphysical properties over Tsukuba (36.1°N, 140.1°E), Japan, on 10 and 22 May 2007. The purpose of the measurement is to study the influence of Asian mineral dust on ice clouds formation in the middle and upper troposphere. The balloon measured the vertical distributions of aerosol number size distribution (0.13 to 3.9 μm in threshold radius, 8 sizes) by use of the optical particle counter, cloud size (10 μ m to 5 mm in the longest dimension), shape, and number concentration by use of the hydrometer videosonde, humidity by use of SnowWhite hygrometer, and temperature and pressure by use of Meisei RS-01G radiosonde between altitudes of 0 and 16 km. The aerosol size distribution showed bimodal distribution with mode radii of <0.13 μm (fine mode) and about 0.8 μm (coarse mode) over the troposphere (0-13.5 km in altitude). The number concentrations ranged from 150 to 1 cm-3 in the fine mode and from 3 to 0.1 cm-3 in the coarse mode. High depolarization ratio (>10%) obtained from the ground-based Raman lidar measurement revealed the presence of nonspherical dust in the coarse mode. Columnar, bullet-like, and irregular ice crystals with 10-400 μm in size were detected between altitudes of 8 and 13 km on 10 May and 10 and 13 km on 22 May. The maximum crystal concentration was 0.15 cm-3. We discuss the possibility of the formation of the ice cloud from the dust based on the result of the measurements.

  11. 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.

  12. Aerosol effective density measurement using scanning mobility particle sizer and quartz crystal microbalance with the estimation of involved uncertainty

    NASA Astrophysics Data System (ADS)

    Sarangi, Bighnaraj; Aggarwal, Shankar G.; Sinha, Deepak; Gupta, Prabhat K.

    2016-03-01

    In this work, we have used a scanning mobility particle sizer (SMPS) and a quartz crystal microbalance (QCM) to estimate the effective density of aerosol particles. This approach is tested for aerosolized particles generated from the solution of standard materials of known density, i.e. ammonium sulfate (AS), ammonium nitrate (AN) and sodium chloride (SC), and also applied for ambient measurement in New Delhi. We also discuss uncertainty involved in the measurement. In this method, dried particles are introduced in to a differential mobility analyser (DMA), where size segregation is done based on particle electrical mobility. Downstream of the DMA, the aerosol stream is subdivided into two parts. One is sent to a condensation particle counter (CPC) to measure particle number concentration, whereas the other one is sent to the QCM to measure the particle mass concentration simultaneously. Based on particle volume derived from size distribution data of the SMPS and mass concentration data obtained from the QCM, the mean effective density (ρeff) with uncertainty of inorganic salt particles (for particle count mean diameter (CMD) over a size range 10-478 nm), i.e. AS, SC and AN, is estimated to be 1.76 ± 0.24, 2.08 ± 0.19 and 1.69 ± 0.28 g cm-3, values which are comparable with the material density (ρ) values, 1.77, 2.17 and 1.72 g cm-3, respectively. Using this technique, the percentage contribution of error in the measurement of effective density is calculated to be in the range of 9-17 %. Among the individual uncertainty components, repeatability of particle mass obtained by the QCM, the QCM crystal frequency, CPC counting efficiency, and the equivalence of CPC- and QCM-derived volume are the major contributors to the expanded uncertainty (at k = 2) in comparison to other components, e.g. diffusion correction, charge correction, etc. Effective density for ambient particles at the beginning of the winter period in New Delhi was measured to be 1.28 ± 0.12 g cm-3

  13. 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.

  14. Measurements Of Sub- 3nm Aerosol Particles In Tropical Rainforest Conditions - Technical Challenges And Solutions

    NASA Astrophysics Data System (ADS)

    Wimmer, D.; Alessandro, F.; Backmann, J.; Manninen, H. E.; Lehtipalo, K.; Petäjä, T.; Kulmala, M. T.

    2014-12-01

    A Particle Size Magnifier (PSM; Vanhanen et al., 2011) was used for studying the sub-3 nm aerosol particles during the second intensive observation period of the GoAmazon campaign. The PSM is using diethylene glycol (DEG) as condensing liquid, which has a low saturation vapour pressure and is hygroscopic. The high supersaturation needed for activating sub-3 nm particles is reached by mixing the sample with clean air saturated with DEG. The measurements took place in Sept-Oct, when typical temperatures at the measurement site are around 303 K, and relative humidity (RH) around 90%. Due to these challenging conditions, in combination with the hygroscopicity of the DEG, careful design and testing of the instrument was required. We developed an inlet reducing the RH at the inlet of the PSM while keeping the diffusion losses of particles in the inlet as low as possible. The inlet design is based on a sintered tube, where dry, pressurized dilution flow is added. Downstream of the sintered tube, a core sampling probe is used. The core sampling allows to sample from the center of the tube, where the highest particle concentration is, while an additional make-up flow allows for a higher sample flow rate. The RH of the ambient, dilution flow and PSM inlet flow are monitored continuously. Tests in the laboratory have shown that the RH could be reduced down to less than 30%, while the ambient RH was 90-100%. The characterization of the inlet regarding diffusion losses lead to a cut off diameter of 1.6 nm, compared to 1.3 nm without inlet. Thus, this new inlet design allows measurements of sub-3 nm particles in tropical rainforest condition.

  15. Aerosol effective density measurement using scanning mobility particle sizer and quartz crystal microbalance with the estimation of involved uncertainty

    NASA Astrophysics Data System (ADS)

    Sarangi, B.; Aggarwal, S. G.; Sinha, D.; Gupta, P. K.

    2015-12-01

    In this work, we have used scanning mobility particle sizer (SMPS) and quartz crystal microbalance (QCM) to estimate the effective density of aerosol particles. This approach is tested for aerosolized particles generated from the solution of standard materials of known density, i.e. ammonium sulfate (AS), ammonium nitrate (AN) and sodium chloride (SC), and also applied for ambient measurement in New Delhi. We also discuss uncertainty involved in the measurement. In this method, dried particles are introduced in to a differential mobility analyzer (DMA), where size segregation was done based on particle electrical mobility. At the downstream of DMA, the aerosol stream is subdivided into two parts. One is sent to a condensation particle counter (CPC) to measure particle number concentration, whereas other one is sent to QCM to measure the particle mass concentration simultaneously. Based on particle volume derived from size distribution data of SMPS and mass concentration data obtained from QCM, the mean effective density (ρeff) with uncertainty of inorganic salt particles (for particle count mean diameter (CMD) over a size range 10 to 478 nm), i.e. AS, SC and AN is estimated to be 1.76 ± 0.24, 2.08 ± 0.19 and 1.69 ± 0.28 g cm-3, which are comparable with the material density (ρ) values, 1.77, 2.17 and 1.72 g cm-3, respectively. Among individual uncertainty components, repeatability of particle mass obtained by QCM, QCM crystal frequency, CPC counting efficiency, and equivalence of CPC and QCM derived volume are the major contributors to the expanded uncertainty (at k = 2) in comparison to other components, e.g. diffusion correction, charge correction, etc. Effective density for ambient particles at the beginning of winter period in New Delhi is measured to be 1.28 ± 0.12 g cm-3. It was found that in general, mid-day effective density of ambient aerosols increases with increase in CMD of particle size measurement but particle photochemistry is an important

  16. Aerosol Measurements of the Fine and Ultrafine Particle Content of Lunar Regolith

    NASA Technical Reports Server (NTRS)

    Greenberg, Paul S.; Chen, Da-Ren; Smith, Sally A.

    2007-01-01

    We report the first quantitative measurements of the ultrafine (20 to 100 nm) and fine (100 nm to 20 m) particulate components of Lunar surface regolith. The measurements were performed by gas-phase dispersal of the samples, and analysis using aerosol diagnostic techniques. This approach makes no a priori assumptions about the particle size distribution function as required by ensemble optical scattering methods, and is independent of refractive index and density. The method provides direct evaluation of effective transport diameters, in contrast to indirect scattering techniques or size information derived from two-dimensional projections of high magnification-images. The results demonstrate considerable populations in these size regimes. In light of the numerous difficulties attributed to dust exposure during the Apollo program, this outcome is of significant importance to the design of mitigation technologies for future Lunar exploration.

  17. 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.

  18. In situ measurements of heterogeneous reactions on ambient aerosol particles: Impacts on atmospheric chemistry and climate

    SciTech Connect

    Bertram, Timothy

    2015-02-11

    Aerosol particles play a critical role in the Earth’s energy budget through the absorption and scattering of radiation, and/or through their ability to form clouds and alter cloud lifetime. Heterogeneous and multi-phase reactions alter the climate-relevant properties of aerosol particles and catalyze reaction pathways that are energetically unfavorable in the gas phase. The chemical composition of aerosol particles dictates the kinetics of heterogeneous and multi-phase reactions. At present, the vast majority of the molecular level information on these processes has been determined in laboratory investigations on model aerosol systems. The work described here provides a comprehensive investigation into the reactivity of complex, ambient aerosol particles is proposed to determine: 1) how representative laboratory investigations of heterogeneous and multi-phase processes conducted on model, simple systems are of the real atmosphere, and 2) the impact of heterogeneous and multi-phase processes on ambient particle optical properties and their ability to nucleate clouds. This work has focused on the uptake kinetics for ammonia (NH3) and dinitrogen pentoxide (N2O5). The results of these investigations will be used to directly improve the representation of heterogeneous and multi-phase processes in global climate models, by identifying the key mechanistic drivers that control the variability in the observed kinetics.

  19. The mixing state of carbonaceous aerosol particles in northern and southern California measured during CARES and CalNex 2010

    NASA Astrophysics Data System (ADS)

    Cahill, J. F.; Suski, K.; Seinfeld, J. H.; Zaveri, R. A.; Prather, K. A.

    2012-11-01

    Carbonaceous aerosols impact climate directly by scattering and absorbing radiation, and hence play a major, although highly uncertain, role in global radiative forcing. Commonly, ambient carbonaceous aerosols are internally mixed with secondary species such as nitrate, sulfate, and ammonium, which influences their optical properties, hygroscopicity, and atmospheric lifetime, thus impacting climate forcing. Aircraft-aerosol time-of-flight mass spectrometry (A-ATOFMS), which measures single-particle mixing state, was used to determine the fraction of organic and soot aerosols that are internally mixed and the variability of their mixing state in California during the Carbonaceous Aerosols and Radiative Effects Study (CARES) and the Research at the Nexus of Air Quality and Climate Change (CalNex) field campaigns in the late spring and early summer of 2010. Nearly 88% of all A-ATOFMS measured particles (100-1000 nm in diameter) were internally mixed with secondary species, with 96% and 75% of particles internally mixed with nitrate and/or sulfate in southern and northern California, respectively. Even though atmospheric particle composition in both regions was primarily influenced by urban sources, the mixing state was found to vary greatly, with nitrate and soot being the dominant species in southern California, and sulfate and organic carbon in northern California. Furthermore, mixing state varied temporally in northern California, with soot becoming the prevalent particle type towards the end of the study as regional pollution levels increased. The results from these studies demonstrate that the majority of ambient carbonaceous particles in California are internally mixed and are heavily influenced by secondary species that are most prevalent in the particular region. Based on these findings, considerations of regionally dominant sources and secondary species, as well as temporal variations of aerosol physical and optical properties, will be required to obtain more

  20. The mixing state of carbonaceous aerosol particles in Northern and Southern California measured during CARES and CalNex 2010

    NASA Astrophysics Data System (ADS)

    Cahill, J. F.; Suski, K.; Seinfeld, J. H.; Zaveri, R. A.; Prather, K. A.

    2012-07-01

    Carbonaceous aerosols impact climate directly by scattering and absorbing radiation, and hence play a major, although highly uncertain, role in global radiative forcing. Commonly, ambient carbonaceous aerosols are internally mixed with secondary species such as nitrate, sulfate, and ammonium, which influences their optical properties, hygroscopicity, and atmospheric lifetime, thus impacting climate forcing. Aircraft-aerosol time-of-flight mass spectrometry (A-ATOFMS), which measures single-particle mixing state, was used to determine the fraction of organic and soot aerosols that are internally mixed and the variability of their mixing state in California during the Carbonaceous Aerosols and Radiative Effects Study (CARES) and the Research at the Nexus of Air Quality and Climate Change (CalNex) field campaigns in the late spring and early summer of 2010. Nearly 88% of all A-ATOFMS measured particles (100-1000 nm in diameter) were internally mixed with secondary species, with 96% and 75% of particles internally mixed with nitrate and/or sulfate in Southern and Northern California, respectively. Even though atmospheric particle composition in both regions was primarily influenced by urban sources, the mixing state was found to vary greatly, with nitrate and soot being the dominant species in Southern California, and sulfate and organic carbon in Northern California. Furthermore, mixing state varied temporally in Northern California, with soot becoming the prevalent particle type towards the end of the study as regional pollution levels increased. The results from these studies demonstrate that the majority of ambient carbonaceous particles in California are internally mixed and are heavily influenced by secondary species that are most prevalent in the particular region. Based on these findings, considerations of regionally dominant sources and secondary species, as well as temporal variations of aerosol physical and optical properties, will be required to obtain more

  1. The mixing state of carbonaceous aerosol particles in northern and southern California measured during CARES and CalNex 2010

    SciTech Connect

    Cahill, John F.; Suski, Kaitlyn; Seinfeld, John H.; Zaveri, Rahul A.; Prather, Kimberly A.

    2012-11-21

    Carbonaceous aerosols impact climate directly by scattering and absorbing radiation, and hence play a major, although highly uncertain, role in global radiative forcing. Commonly, ambient carbonaceous aerosols are internally mixed with secondary species such as nitrate, sulfate, and ammonium, which influence their climate impacts through optical properties, hygroscopicity, and atmospheric lifetime. Aircraft-aerosol time-of-flight mass spectrometry (A-ATOFMS), which measures single-particle mixing state, was used to determine the fraction of organic and soot aerosols that were internally mixed and the variability of their mixing state in California during the Carbonaceous Aerosol and Radiative Effects Study (CARES) and the Research at the Nexus of Air Quality and Climate Change (CalNex) field campaigns in the late spring and early summer of 2010. Nearly 88% of all A-ATOFMS measured particles (100-1000 nm in diameter) were internally mixed with secondary species, with 96% and 75% of particles internally mixed with nitrate and/or sulfate in southern and northern California, respectively. Even though atmospheric particle composition in both regions was primarily influenced by urban sources, the mixing state was found to vary greatly, with nitrate and soot being the dominant species in southern California, and sulfate and organic carbon in northern California. Furthermore, mixing state varied temporally in northern California, with soot becoming the prevalent particle type towards the end of the study as regional pollution levels increased. The results from these studies demonstrate that the majority of ambient carbonaceous particles are internally mixed and are heavily influenced by secondary species that are most predominant in each region. Based on these findings, considerations of regionally dominant sources and secondary species, as well as temporal variations of aerosol physical and optical properties, will be required to obtain more accurate predictions of the

  2. Urban organic aerosols measured by single particle mass spectrometry in the megacity of London

    NASA Astrophysics Data System (ADS)

    Dall'Osto, M.; Harrison, R. M.

    2012-05-01

    During the month of October 2006, as part of the REPARTEE-I experiment (Regent's Park and Tower Environmental Experiment) an Aerosol Time-Of-Flight Mass Spectrometer (ATOFMS) was deployed at an urban background location in the city of London, UK. Fifteen particle types were classified, some of which were already discussed (Dall'Osto et al., 2009a,b; Harrison et al., 2012). In this manuscript the origins and properties of four unreported particle types postulated to be due to locally generated aerosols, independent of the air mass type advected into London, are examined. One particle type, originating from lubricating oil (referred to as Ca-EC), was associated with morning rush hour traffic emissions. A second particle type, composed of both inorganic and organic species (called Na-EC-OC), was found enhanced in particle number concentration during evening time periods, and is likely to originate from a source operating at this time of day, or more probably from condensation of semi-volatile species. A third class, internally mixed with organic carbon and sulphate (called OC), was found to spike both in the morning and evenings although it could not unambiguously associated with a specific source or atmospheric process. The fourth class (Secondary Organic Aerosols - Polycyclic Aromatic Hydrocarbon; SOA-PAH) exhibited maximum frequency during the warmest part of the day, and a number of factors point towards secondary aerosol production from traffic-related volatile aromatic compounds. Single particle mass spectra of this particle type showed an oxidized polycyclic aromatic compound signature. A comparison of ATOFMS particle class data is then made with factors obtained by Positive Matrix Factorization and PAH signatures obtained from Aerosol Mass Spectrometer (AMS) data (Allan et al., 2010). Both the Ca-EC and OC particle types correlate with primary Hydrocarbon-like Organic Aerosol (HOA, R2 = 0.65 and 0.50 respectively), and Na-EC-OC correlates weakly with the AMS

  3. Hygroscopic Measurements of Aerosol Particles in the San Joaquin Valley California during the DRAGON and Discover AQ Campaign 2013

    NASA Astrophysics Data System (ADS)

    Orozco, D.; Delgado, R.; Hoff, R. M.

    2013-12-01

    In the ambient atmosphere, aerosol particles experience hygroscopic growth due to the influence of relative humidity (RH). Wet aerosols particles are larger than their dry equivalents, therefore they scatter more light. Quantitative knowledge of the RH effect and its influence on the light scattering coefficient on aerosol particles is of substantial importance when comparing ground based observations with other optical aerosol measurements techniques such satellite and sunphotometric retrievals of aerosol optical depth. The DISCOVER-AQ campaign is focused in improving the interpretation and relation between satellite observations and surface conditions related to air quality. In the winter of 2013, this campaign was held in the San Joaquin Valley, California, where systematic and concurrent observations of column integrated surface, and vertically resolved distributions of aerosols and trace gases relevant to air quality and their evolution during the day were observed. Different instruments such as particulate samplers, lidars, meteorological stations and airborne passive and active monitoring were coordinated to measure the aerosol structure of the San Joaquin Valley in a simultaneous fashion. A novel humidifier-dryer system for a TSI 3563 Nephelometer was implemented in the Penn State University NATIVE trailer located in Porterville California in order to measure the scattering coefficient σsp(λ) at three different wavelengths (λ=440, 550 and 700nm) in a RH range from 30 to 95%. The system was assembled by combining Nafion tubes to humidify and dry the aerosols and stepping motor valves to control the flow and the amount of humidity entering to the Nephelometer. Measurements in Porterville California reached dry scattering coefficient readings greater than 300Mm-1 at 550nm indicating the presence of a large amount of particles in the region. However, the ratio between scattering coefficients at high and low humidity, called the enhancement factor f

  4. A broad supersaturation scanning (BS2) approach for rapid measurement of aerosol particle hygroscopicity and cloud condensation nuclei activity

    NASA Astrophysics Data System (ADS)

    Su, Hang; Cheng, Yafang; Ma, Nan; Wang, Zhibin; Wang, Xiaoxiang; Pöhlker, Mira L.; Nillius, Björn; Wiedensohler, Alfred; Pöschl, Ulrich

    2016-10-01

    The activation and hygroscopicity of cloud condensation nuclei (CCN) are key to the understanding of aerosol-cloud interactions and their impact on climate. They can be measured by scanning the particle size and supersaturation in CCN measurements. The scanning of supersaturation is often time-consuming and limits the temporal resolution and performance of CCN measurements. Here we present a new approach, termed the broad supersaturation scanning (BS2) method, in which a range of supersaturation is simultaneously scanned, reducing the time interval between different supersaturation scans. The practical applicability of the BS2 approach is demonstrated with nano-CCN measurements of laboratory-generated aerosol particles. Model simulations show that the BS2 approach may also be applicable for measuring CCN activation of ambient mixed particles. Due to its fast response and technical simplicity, the BS2 approach may be well suited for aircraft and long-term measurements. Since hygroscopicity is closely related to the fraction of organics/inorganics in aerosol particles, a BS2-CCN counter can also serve as a complementary sensor for fast detection/estimation of aerosol chemical compositions.

  5. Insights into secondary organic aerosol formation mechanisms from measured gas/particle partitioning of specific organic tracer compounds.

    PubMed

    Zhao, Yunliang; Kreisberg, Nathan M; Worton, David R; Isaacman, Gabriel; Weber, Robin J; Liu, Shang; Day, Douglas A; Russell, Lynn M; Markovic, Milos Z; VandenBoer, Trevor C; Murphy, Jennifer G; Hering, Susanne V; Goldstein, Allen H

    2013-04-16

    In situ measurements of organic compounds in both gas and particle phases were made with a thermal desorption aerosol gas chromatography (TAG) instrument. The gas/particle partitioning of phthalic acid, pinonaldehyde, and 6,10,14-trimethyl-2-pentadecanone is discussed in detail to explore secondary organic aerosol (SOA) formation mechanisms. Measured fractions in the particle phase (f(part)) of 6,10,14-trimethyl-2-pentadecanone were similar to those expected from the absorptive gas/particle partitioning theory, suggesting that its partitioning is dominated by absorption processes. However, f(part) of phthalic acid and pinonaldehyde were substantially higher than predicted. The formation of low-volatility products from reactions of phthalic acid with ammonia is proposed as one possible mechanism to explain the high f(part) of phthalic acid. The observations of particle-phase pinonaldehyde when inorganic acids were fully neutralized indicate that inorganic acids are not required for the occurrence of reactive uptake of pinonaldehyde on particles. The observed relationship between f(part) of pinonaldehyde and relative humidity suggests that the aerosol water plays a significant role in the formation of particle-phase pinonaldehyde. Our results clearly show it is necessary to include multiple gas/particle partitioning pathways in models to predict SOA and multiple SOA tracers in source apportionment models to reconstruct SOA.

  6. Deposition of aerosol particles in human lungs: in vivo measurements and modeling

    EPA Science Inventory

    The deposition dose and site of inhaled particles within the lung are the key determinants in health risk assessment of particulate pollutants. Accurate dose estimation, however, is a formidable task because aerosol transport and deposition in the lung are governed by many factor...

  7. Nozzles for Focusing Aerosol Particles

    DTIC Science & Technology

    2009-10-01

    control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. 1. REPORT DATE ( DD -MM-YYYY) October 2009 2. REPORT TYPE Final 3. DATES...Figures Figure 1. The design of the first-generation aerodynamic focusing nozzle for aerosol particles used for SPFS and TAOS instrument prototypes...Some nozzles were fabricated in aluminum and some in steel. It has been used for SPFS and TAOS measurement technologies both in the laboratory and

  8. Reconciliation of coarse mode sea-salt aerosol particle size measurements and parameterizations at a subtropical ocean receptor site

    NASA Astrophysics Data System (ADS)

    Reid, Jeffrey S.; Brooks, Barbara; Crahan, Katie K.; Hegg, Dean A.; Eck, Thomas F.; O'Neill, Norm; de Leeuw, Gerrit; Reid, Elizabeth A.; Anderson, Kenneth D.

    2006-01-01

    In August/September of 2001, the R/P FLIP and CIRPAS Twin Otter research aircraft were deployed to the eastern coast of Oahu, Hawaii, as part of the Rough Evaporation Duct (RED) experiment. Goals included the study of the air/sea exchange, turbulence, and sea-salt aerosol particle characteristics at the subtropical marine Pacific site. Here we examine coarse mode particle size distributions. Similar to what has been shown for airborne dust, optical particle counters such as the Forward Scattering Spectrometer Probe (FSSP), Classical Scattering Aerosol Spectrometer Probe (CSASP) and the Cloud Aerosol Spectrometer (CAS) within the Cloud Aerosol and Precipitation Spectrometer (CAPS) instrument systematically overestimate particle size, and consequently volume, for sea salt particles. Ground-based aerodynamic particle sizers (APS) and AERONET inversions yield much more reasonable results. A wing pod mounted APS gave mixed results and may not be appropriate for marine boundary layer studies. Relating our findings to previous studies does much to explain the bulk of the differences in the literature and leads us to conclude that the largest uncertainty facing flux and airborne cloud/aerosol interaction studies is likely due to the instrumentation itself. To our knowledge, there does not exist an in situ aircraft system that adequately measures the ambient volume distribution of coarse mode sea salt particles. Most empirically based sea salt flux parameterizations can trace their heritage to a clearly biased measurement technique. The current "state of the art" in this field prevents any true form of clear sky radiative "closure" for clean marine environments.

  9. A method for the direct measurement of surface tension of collected atmospherically relevant aerosol particles using atomic force microscopy

    NASA Astrophysics Data System (ADS)

    Hritz, Andrew D.; Raymond, Timothy M.; Dutcher, Dabrina D.

    2016-08-01

    Accurate estimates of particle surface tension are required for models concerning atmospheric aerosol nucleation and activation. However, it is difficult to collect the volumes of atmospheric aerosol required by typical instruments that measure surface tension, such as goniometers or Wilhelmy plates. In this work, a method that measures, ex situ, the surface tension of collected liquid nanoparticles using atomic force microscopy is presented. A film of particles is collected via impaction and is probed using nanoneedle tips with the atomic force microscope. This micro-Wilhelmy method allows for direct measurements of the surface tension of small amounts of sample. This method was verified using liquids, whose surface tensions were known. Particles of ozone oxidized α-pinene, a well-characterized system, were then produced, collected, and analyzed using this method to demonstrate its applicability for liquid aerosol samples. It was determined that oxidized α-pinene particles formed in dry conditions have a surface tension similar to that of pure α-pinene, and oxidized α-pinene particles formed in more humid conditions have a surface tension that is significantly higher.

  10. Regional-scale simulations of fungal spore aerosols using an emission parameterization adapted to local measurements of fluorescent biological aerosol particles

    NASA Astrophysics Data System (ADS)

    Hummel, M.; Hoose, C.; Gallagher, M.; Healy, D. A.; Huffman, J. A.; O'Connor, D.; Pöschl, U.; Pöhlker, C.; Robinson, N. H.; Schnaiter, M.; Sodeau, J. R.; Toprak, E.; Vogel, H.

    2014-04-01

    Fungal spores as a prominent type of primary biological aerosol particles (PBAP) have been incorporated into the COSMO-ART regional atmospheric model, using and comparing three different emission parameterizations. Two literature-based emission rates derived from fungal spore colony counts and chemical tracer measurements were used as a parameterization baseline for this study. A third, new emission parameterization was adapted to field measurements of fluorescent biological aerosol particles (FBAP) from four locations across Northern Europe. FBAP concentrations can be regarded as a lower estimate of total PBAP concentrations. Size distributions of FBAP often show a distinct mode at approx. 3 μm, corresponding to a diameter range characteristic for many fungal spores. Previous studies have suggested the majority of FBAP in several locations are dominated by fungal spores. Thus, we suggest that simulated fungal spore concentrations obtained from the emission parameterizations can be compared to the sum of total FBAP concentrations. A comparison reveals that parameterized estimates of fungal spore concentrations based on literature numbers underestimate measured FBAP concentrations. In agreement with measurement data, the model results show a diurnal cycle in simulated fungal spore concentrations, which may develop partially as a consequence of a varying boundary layer height between day and night. Measured FBAP and simulated fungal spore concentrations also correlate similarly with simulated temperature and humidity. These meteorological variables, together with leaf area index, were chosen to drive the new emission parameterization discussed here. Using the new emission parameterization on a model domain covering Western Europe, fungal spores in the lowest model layer comprise a fraction of 15% of the total aerosol mass over land and reach average number concentrations of 26 L-1. The results confirm that fungal spores and biological particles may account for a

  11. Spatial and temporal distributions of ice nucleating particles during the Atmospheric Radiation Measurement (ARM) Cloud Aerosol Precipitation Experiment (ACAPEX)

    NASA Astrophysics Data System (ADS)

    Levin, E. J.; DeMott, P. J.; Suski, K. J.; Boose, Y.; Hill, T. C. J.; McCluskey, C. S.; Schill, G. P.; Duncan, D.; Al-Mashat, H.; Prather, K. A.; Sedlacek, A. J., III; Tomlinson, J. M.; Mei, F.; Hubbe, J. M.; Pekour, M. S.; Leung, L. R.; Kreidenweis, S. M.

    2016-12-01

    California is currently under drought conditions and changes in precipitation due to future climate change scenarios are uncertain. Thus, understanding the controlling factors for precipitation in this region, and having the capability to accurately model these scenarios, is important. A crucial area in understanding precipitation is in the interplay between atmospheric moisture and aerosols. Specifically, ice nucleation in clouds is an important process controlling precipitation formation. A major component of CA's yearly precipitation comes from wintertime atmospheric river (AR) events which were the focus of the 2015 Atmospheric Radiation Measurement (ARM) Cloud Aerosol Precipitation Experiment (ACAPEX) and CalWater 2 campaigns. These two campaigns provided sampling platforms on four aircraft, including the ARM Aerial Facility G-1, as well as the NOAA Ron Brown research vessel and at a ground station at Bodega Bay, CA. Measurements of ice nucleating particles (INPs) were made with the Colorado State University (CSU) Continuous Flow Diffusion Chamber (CFDC) aboard the G-1 and at Bodega Bay, and using aerosol filter collections on these platforms as well as the Ron Brown for post-processing via immersion freezing in the CSU Ice Spectrometer. Aerosol composition was measured aboard the G-1 with the Aerosol Time-of-Flight Mass Spectrometer (ATOFMS). Both the CFDC and ATOFMS sampled off of an isokinetic inlet when flying in clear air and a counter-flow virtual impactor in clouds to capture ice crystal and cloud droplet residuals. In this presentation we present ice nucleating particle concentrations before, during and after an AR event from air, ground and ocean-based measurements. We also examine INP concentration variability in orographic clouds and in clear air at altitude along the Sierra Nevada range, in the marine boundary layer and through the Central Valley, and relate these INP measurements to other aerosol physical and chemical properties.

  12. Direct measurements of the optical cross sections and refractive indices of individual volatile and hygroscopic aerosol particles.

    PubMed

    Mason, B J; Cotterell, M I; Preston, T C; Orr-Ewing, A J; Reid, J P

    2015-06-04

    We present measurements of the evolving extinction cross sections of individual aerosol particles (spanning 700-2500 nm in radius) during the evaporation of volatile components or hygroscopic growth using a combination of a single particle trap formed from a Bessel light beam and cavity ring-down spectroscopy. For single component organic aerosol droplets of 1,2,6-hexanetriol, polyethylene glycol 400, and glycerol, the slow evaporation of the organic component (over time scales of 1000 to 10,000 s) leads to a time-varying size and extinction cross section that can be used to estimate the refractive index of the droplet. Measurements on binary aqueous-inorganic aerosol droplets containing one of the inorganic solutes ammonium bisulfate, ammonium sulfate, sodium nitrate, or sodium chloride (over time scales of 1000 to 15,000 s) under conditions of changing relative humidity show that extinction cross-section measurements are consistent with expectations from accepted models for the variation in droplet refractive index with hygroscopic growth. In addition, we use these systems to establish an experimental protocol for future single particle extinction measurements. The advantages of mapping out the evolving light extinction cross-section of an individual particle over extended time frames accompanied by hygroscopic cycling or component evaporation are discussed.

  13. 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.

  14. Measurements of the evaporation and hygroscopic response of single fine-mode aerosol particles using a Bessel beam optical trap.

    PubMed

    Cotterell, Michael I; Mason, Bernard J; Carruthers, Antonia E; Walker, Jim S; Orr-Ewing, Andrew J; Reid, Jonathan P

    2014-02-07

    A single horizontally-propagating zeroth order Bessel laser beam with a counter-propagating gas flow was used to confine single fine-mode aerosol particles over extended periods of time, during which process measurements were performed. Particle sizes were measured by the analysis of the angular variation of light scattered at 532 nm by a particle in the Bessel beam, using either a probe beam at 405 nm or 633 nm. The vapour pressures of glycerol and 1,2,6-hexanetriol particles were determined to be 7.5 ± 2.6 mPa and 0.20 ± 0.02 mPa respectively. The lower volatility of hexanetriol allowed better definition of the trapping environment relative humidity profile over the measurement time period, thus higher precision measurements were obtained compared to those for glycerol. The size evolution of a hexanetriol particle, as well as its refractive index at wavelengths 532 nm and 405 nm, were determined by modelling its position along the Bessel beam propagation length while collecting phase functions with the 405 nm probe beam. Measurements of the hygroscopic growth of sodium chloride and ammonium sulfate have been performed on particles as small as 350 nm in radius, with growth curves well described by widely used equilibrium state models. These are the smallest particles for which single-particle hygroscopicity has been measured and represent the first measurements of hygroscopicity on fine mode and near-accumulation mode aerosols, the size regimes bearing the most atmospheric relevance in terms of loading, light extinction and scattering. Finally, the technique is contrasted with other single particle and ensemble methods, and limitations are assessed.

  15. PASSIVE AEROSOL SAMPLER FOR CHARACTERIZATION, AMBIENT CONCENTRATION, AND PARTICLE SIZE MEASUREMENT

    EPA Science Inventory

    This is an extended abstract of a presentation made at the Air and Waste Management Association's Symposium on Air Quality Measurement Methods and Technology, Durham, NC, May 9-11, 2006. The abstract describes the theory, design, and initial testing of a passive aerosol sampler f...

  16. 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...

  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. Combined use of optical and electron microscopic techniques for the measurement of hygroscopic property, chemical composition, and morphology of individual aerosol particles.

    PubMed

    Ahn, Kang-Ho; Kim, Sun-Man; Jung, Hae-Jin; Lee, Mi-Jung; Eom, Hyo-Jin; Maskey, Shila; Ro, Chul-Un

    2010-10-01

    In this work, an analytical method for the characterization of the hygroscopic property, chemical composition, and morphology of individual aerosol particles is introduced. The method, which is based on the combined use of optical and electron microscopic techniques, is simple and easy to apply. An optical microscopic technique was used to perform the visual observation of the phase transformation and hygroscopic growth of aerosol particles on a single particle level. A quantitative energy-dispersive electron probe X-ray microanalysis, named low-Z particle EPMA, was used to perform a quantitative chemical speciation of the same individual particles after the measurement of the hygroscopic property. To validate the analytical methodology, the hygroscopic properties of artificially generated NaCl, KCl, (NH(4))(2)SO(4), and Na(2)SO(4) aerosol particles of micrometer size were investigated. The practical applicability of the analytical method for studying the hygroscopic property, chemical composition, and morphology of ambient aerosol particles is demonstrated.

  19. A comparison of lidar and balloon-borne particle counter measurements of the stratospheric aerosol 1974-1980

    NASA Astrophysics Data System (ADS)

    Swissler, T. J.; Hamill, P.; Osborn, M.; Russell, P. B.; McCormick, M. P.

    1982-04-01

    The optical radar measurements considered in the present investigation are those which have been obtained routinely at Hampton, VA (37.1 deg N, 76.3 deg W) since 1974. The dustsonde measurements are those made monthly at Laramie, WY (41.2 deg N, 105 deg W). The extensive data sets acquired with these two instruments during the time period 1974-80 permit a long-term comparison of the two different measurement techniques. The balloon-borne dustsonde pumps ambient air in a well-defined stream through an illuminated chamber where individual aerosol particles scatter light into photodetectors. The optical radar system used in the studies has a ruby laser with a 48-inch Cassegrainian configured telescope mounted on a mobile platform to collect the backscattered laser light. The investigation shows that optical radar measurements, dustsonde measurements, and realistic optical models together give a very consistent picture of stratospheric aerosol behavior.

  20. 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

  1. 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

  2. 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

  3. Complementary online aerosol mass spectrometry and offline FT-IR spectroscopy measurements: Prospects and challenges for the analysis of anthropogenic aerosol particle emissions

    NASA Astrophysics Data System (ADS)

    Faber, Peter; Drewnick, Frank; Bierl, Reinhard; Borrmann, Stephan

    2017-10-01

    The aerosol mass spectrometer (AMS) is well established in investigating highly time-resolved dynamics of submicron aerosol chemical composition including organic aerosol (OA). However, interpretation of mass spectra on molecular level is limited due to strong fragmentation of organic substances and potential reactions inside the AMS ion chamber. Results from complementary filter-based FT-IR absorption measurements were used to explain features in high-resolution AMS mass spectra of different types of OA (e.g. cooking OA, cigarette smoking OA, wood burning OA). Using this approach some AMS fragment ions were validated in this study as appropriate and rather specific markers for a certain class of organic compounds for all particle types under investigation. These markers can therefore be used to get deeper insights in the chemical composition of OA based on AMS mass spectra in upcoming studies. However, the specificity of other fragment ions such as C2H4O2+ (m/z 60.02114) remains ambiguous. In such cases, complementary FT-IR measurements allow the interpretation of highly time-resolved AMS mass spectra at the level of molecular functional groups. Furthermore, this study discusses the challenges in reducing inorganic interferences (e.g. from water and ammonium salts) in FT-IR spectra of atmospheric aerosols to decrease spectral uncertainties for better comparisons and, thus, to get more robust results.

  4. Regional-scale simulations of fungal spore aerosols using an emission parameterization adapted to local measurements of fluorescent biological aerosol particles

    NASA Astrophysics Data System (ADS)

    Hummel, M.; Hoose, C.; Gallagher, M.; Healy, D. A.; Huffman, J. A.; O'Connor, D.; Pöschl, U.; Pöhlker, C.; Robinson, N. H.; Schnaiter, M.; Sodeau, J. R.; Stengel, M.; Toprak, E.; Vogel, H.

    2015-06-01

    Fungal spores as a prominent type of primary biological aerosol particles (PBAP) have been incorporated into the COSMO-ART (Consortium for Small-scale Modelling-Aerosols and Reactive Trace gases) regional atmospheric model. Two literature-based emission rates for fungal spores derived from fungal spore colony counts and chemical tracer measurements were used as a parameterization baseline for this study. A third, new emission parameterization for fluorescent biological aerosol particles (FBAP) was adapted to field measurements from four locations across Europe. FBAP concentrations can be regarded as a lower estimate of total PBAP concentrations. Size distributions of FBAP often show a distinct mode at approx. 3 μm, corresponding to a diameter range characteristic for many fungal spores. Previous studies for several locations have suggested that FBAP are in many cases dominated by fungal spores. Thus, we suggest that simulated FBAP and fungal spore concentrations obtained from the three different emission parameterizations can be compared to FBAP measurements. The comparison reveals that simulated fungal spore concentrations based on literature emission parameterizations are lower than measured FBAP concentrations. In agreement with the measurements, the model results show a diurnal cycle in simulated fungal spore concentrations, which may develop partially as a consequence of a varying boundary layer height between day and night. Temperature and specific humidity, together with leaf area index (LAI), were chosen to drive the new emission parameterization which is fitted to the FBAP observations. The new parameterization results in similar root mean square errors (RMSEs) and correlation coefficients compared to the FBAP observations as the previously existing fungal spore emission parameterizations, with some improvements in the bias. Using the new emission parameterization on a model domain covering western Europe, FBAP in the lowest model layer comprise a

  5. Stratospheric Aerosol Measurements

    NASA Technical Reports Server (NTRS)

    Pueschel, Rudolf, F.; Gore, Warren J. (Technical Monitor)

    1998-01-01

    Stratospheric aerosols affect the atmospheric energy balance by scattering and absorbing solar and terrestrial radiation. They also can alter stratospheric chemical cycles by catalyzing heterogeneous reactions which markedly perturb odd nitrogen, chlorine and ozone levels. Aerosol measurements by satellites began in NASA in 1975 with the Stratospheric Aerosol Measurement (SAM) program, to be followed by the Stratospheric Aerosol and Gas Experiment (SAGE) starting in 1979. Both programs employ the solar occultation, or Earth limb extinction, techniques. Major results of these activities include the discovery of polar stratospheric clouds (PSCs) in both hemispheres in winter, illustrations of the impacts of major (El Chichon 1982 and Pinatubo 1991) eruptions, and detection of a negative global trend in lower stratospheric/upper tropospheric aerosol extinction. This latter result can be considered a triumph of successful worldwide sulfur emission controls. The SAGE record will be continued and improved by SAGE III, currently scheduled for multiple launches beginning in 2000 as part of the Earth Observing System (EOS). The satellite program has been supplemented by in situ measurements aboard the ER-2 (20 km ceiling) since 1974, and from the DC-8 (13 km ceiling) aircraft beginning in 1989. Collection by wire impactors and subsequent electron microscopic and X-ray energy-dispersive analyses, and optical particle spectrometry have been the principle techniques. Major findings are: (1) The stratospheric background aerosol consists of dilute sulfuric acid droplets of around 0.1 micrometer modal diameter at concentration of tens to hundreds of monograms per cubic meter; (2) Soot from aircraft amounts to a fraction of one percent of the background total aerosol; (3) Volcanic eruptions perturb the sulfuric acid, but not the soot, aerosol abundance by several orders of magnitude; (4) PSCs contain nitric acid at temperatures below 195K, supporting chemical hypotheses

  6. Stratospheric Aerosol Measurements

    NASA Technical Reports Server (NTRS)

    Pueschel, Rudolf, F.; Gore, Warren J. (Technical Monitor)

    1998-01-01

    Stratospheric aerosols affect the atmospheric energy balance by scattering and absorbing solar and terrestrial radiation. They also can alter stratospheric chemical cycles by catalyzing heterogeneous reactions which markedly perturb odd nitrogen, chlorine and ozone levels. Aerosol measurements by satellites began in NASA in 1975 with the Stratospheric Aerosol Measurement (SAM) program, to be followed by the Stratospheric Aerosol and Gas Experiment (SAGE) starting in 1979. Both programs employ the solar occultation, or Earth limb extinction, techniques. Major results of these activities include the discovery of polar stratospheric clouds (PSCs) in both hemispheres in winter, illustrations of the impacts of major (El Chichon 1982 and Pinatubo 1991) eruptions, and detection of a negative global trend in lower stratospheric/upper tropospheric aerosol extinction. This latter result can be considered a triumph of successful worldwide sulfur emission controls. The SAGE record will be continued and improved by SAGE III, currently scheduled for multiple launches beginning in 2000 as part of the Earth Observing System (EOS). The satellite program has been supplemented by in situ measurements aboard the ER-2 (20 km ceiling) since 1974, and from the DC-8 (13 km ceiling) aircraft beginning in 1989. Collection by wire impactors and subsequent electron microscopic and X-ray energy-dispersive analyses, and optical particle spectrometry have been the principle techniques. Major findings are: (1) The stratospheric background aerosol consists of dilute sulfuric acid droplets of around 0.1 micrometer modal diameter at concentration of tens to hundreds of monograms per cubic meter; (2) Soot from aircraft amounts to a fraction of one percent of the background total aerosol; (3) Volcanic eruptions perturb the sulfuric acid, but not the soot, aerosol abundance by several orders of magnitude; (4) PSCs contain nitric acid at temperatures below 195K, supporting chemical hypotheses

  7. Sulfur isotope measurements of submicrometer sulfate aerosol particles over the Pacific Ocean

    NASA Technical Reports Server (NTRS)

    Calhoun, Julie A.; Charlson, Robert J.; Bates, Timothy S.

    1991-01-01

    Stable isotopes were used to analyze the submicron-size sulfate aerosol particles in the atmosphere over the Pacific Ocean, together with the air-mass back trajectories, in order to test the hypothesis of Charlson et al. (1987) who suggested that, over the remote ocean areas, the primary source of atmospheric nonseasalt (NSS) sulfate is marine emissions of dimethylsulfide (DMS). The observed results of isotopic fractionation between the seawater sulfate and NSS sulfate fractions was found to be consistent with the isotopic fractionation predicted for the transformation of the seawater sulfate to the atmospheric NSS sulfate via a DMS path way, supporting the hypothesis of Charlson et al.

  8. Improved non-invasive method for aerosol particle charge measurement employing in-line digital holography

    NASA Astrophysics Data System (ADS)

    Tripathi, Anjan Kumar

    Electrically charged particles are found in a wide range of applications ranging from electrostatic powder coating, mineral processing, and powder handling to rain-producing cloud formation in atmospheric turbulent flows. In turbulent flows, particle dynamics is influenced by the electric force due to particle charge generation. Quantifying particle charges in such systems will help in better predicting and controlling particle clustering, relative motion, collision, and growth. However, there is a lack of noninvasive techniques to measure particle charges. Recently, a non-invasive method for particle charge measurement using in-line Digital Holographic Particle Tracking Velocimetry (DHPTV) technique was developed in our lab, where charged particles to be measured were introduced to a uniform electric field, and their movement towards the oppositely charged electrode was deemed proportional to the amount of charge on the particles (Fan Yang, 2014 [1]). However, inherent speckle noise associated with reconstructed images was not adequately removed and therefore particle tracking data was contaminated. Furthermore, particle charge calculation based on particle deflection velocity neglected the particle drag force and rebound effect of the highly charged particles from the electrodes. We improved upon the existing particle charge measurement method by: 1) hologram post processing, 2) taking drag force into account in charge calculation, 3) considering rebound effect. The improved method was first fine-tuned through a calibration experiment. The complete method was then applied to two different experiments, namely conduction charging and enclosed fan-driven turbulence chamber, to measure particle charges. In all three experiments conducted, the particle charge was found to obey non-central t-location scale family of distribution. It was also noted that the charge distribution was insensitive to the change in voltage applied between the electrodes. The range of voltage

  9. Aerosol mass spectrometer measurements of organic aerosol

    NASA Astrophysics Data System (ADS)

    Worsnop, D.; Canagaratna, M.; Jayne, J.; Boudries, H.; Onasch, T.; Jimenez, J.; Slowik, J.; Coe, H.

    2003-12-01

    Organic species are known to be ubiquitous and comprise a significant component of ambient aerosols. Identifying the sources, chemical compositions, and loadings of particulate organics remains a difficult, yet important problem as organic components may affect the formation, hygroscopicity, growth, reactivity, and radiative effects of ambient particles. Unraveling this complexity inherently must rely on chemical information (such as off-line filter analyses and collector/concentrator techniques), but also on real-time instruments that are capable of combining particle physical measurements (size, density) with chemical speciation information. The Aerodyne Aerosol Mass Spectrometer (AMS) has been deployed on many different measurement platforms around the world and is generating a rich data set capable of providing insight into the complexity of particulate organics. Highlights of the aerosol measurements will be presented. Although the AMS cannot uniquely classify individual organic compounds, it has been become evident that classes of organic compounds can be identified. These include the identification of a size-resolved chemical signature for fresh diesel and gasoline particulate emissions. Electron impact ionization mass spectral signatures of oxidized organic components and the temporal and spatial relationships between the signatures for fresh organic emissions and aged/oxidized organic components. Laboratory studies on soot and other organic aerosols will also be presented within this context.

  10. Dual-wavelength-excitation single-particle fluorescence spectrometer/particle sorter for real-time measurement of organic carbon and biological aerosols

    NASA Astrophysics Data System (ADS)

    Pan, Yong-Le; Pinnick, Ron G.; Hill, Steven C.; Huang, Hermes; Chang, Richard K.

    2008-10-01

    We report the development of a Single-Particle Fluorescence Spectrometer (SPFS) system capable of measuring two UV-laser excited fluorescence spectra from a single particle on-the-fly. The two dispersed fluorescence spectra are obtained from excitation by two lasers at different wavelengths (263 nm and 351 nm). The SPFS samples single particles with sizes primarily in the 1-10 μm range. The fluorescence spectra are recorded from 280 nm to 600 nm (in 20 channels) for 263 nm excitation and from 370 nm to 700 nm (in 22 channels) for 351 nm excitation. The elastic scattering (channel 4 and 9) is also recorded for sizing each particle. A time stamp for single particles is marked with a variable time interval resolution from 10 ms to 10 minutes. The SPFS employs a virtual-impactor concentrator to concentrate respirable-sized particles with a resulting (size-dependent) effective flow rate of around 100 liters/min. The SPFS can measure single-particle spectra at a maximum rate of 90,000/sec, although the highest rates we have experienced for the ambient are only several hundred/sec. When the SPFS is combined with an aerodynamic deflector (puffer) to sort particles according to their fluorescence spectral characteristics, the SPFS/puffer system can selectively deflect and collect an enriched sample of targeted particles (at rates limited by the puffer) of 1200 particles/sec, for further examination. In laboratory tests, aerosol particles with similar UV-LIF spectra (e.g. B. subtilis and E.coli) are puffed into the reservoir of a micro-fluidic cell, where fluorescent-labeled antibodies bind to them and were classified by their labeled fluorescence. Measurements of the background ambient aerosol with the SPFS system made at sites with different regional climate (Connecticut, Maryland, and New Mexico) were clustered (unstructured hierarchical analysis) into 8-10 groups, with over 90% of all the fluorescent particles contained within these clusters (threshold dot product=0

  11. Development of DMA-Faraday Cup Electrometer system for measurement of submicron aerosol particles

    NASA Astrophysics Data System (ADS)

    Shimada, Manabu; Iskandar, Ferry; Okuyama, Kikuo

    2000-08-01

    A measurement system consisting of a Long Differential Mobility Analyzer (LDMA) and a Faraday Cup Electrometer (FCE) was developed to investigate the performance of the system for measuring the size distribution of submicron airborne particles. The LDMA was designed to have an extended classification zone in order to classify particles up to 1 μm. A new data reduction program was prepared to convert the electrical mobility distribution data obtained with the FCE into a particle size distribution. By using the program, the size distribution of TiO2 particles determined by the present system agreed with that measured by a combination of the LDMA and a condensation nucleus counter. The system was also evaluated using polydispersed, submicron SiO2 particles generated by a spray drying method. The results show that the present system performs well and is a useful tool available for measuring particles size over a wide range.

  12. Characterization of black carbon-containing particles from soot particle aerosol mass spectrometer measurements on the R/V Atlantis during CalNex 2010

    NASA Astrophysics Data System (ADS)

    Massoli, Paola; Onasch, Timothy B.; Cappa, Christopher D.; Nuamaan, Ibraheem; Hakala, Jani; Hayden, Katherine; Li, Shao-Meng; Sueper, Donna T.; Bates, Timothy S.; Quinn, Patricia K.; Jayne, John T.; Worsnop, Douglas R.

    2015-03-01

    We present mass spectrometry measurements of black carbon-containing particles made on board the R/V Atlantis during the CalNex (California Research at the Nexus of Air Quality and Climate Change) 2010 study using an Aerodyne Research Inc. soot particle aerosol mass spectrometer (SP-AMS). The R/V Atlantis was deployed to characterize air masses moving offshore the California coast and to assess emissions from sources in urban ports. This work presents a first detailed analysis of the size-resolved chemical composition of refractory black carbon (rBC) and of the associated coating species (NR-PMBC). A colocated standard high-resolution aerosol mass spectrometer (HR-AMS) measured the total nonrefractory submicron aerosol (NR-PM1). Our results indicate that, on average, 35% of the measured NR-PM1 mass (87% of the primary and 28% of the secondary NR-PM1, as obtained from the mass-weighted average of the NR-PMBC species) was associated with rBC. The peak in the average size distribution of the rBC-containing particles measured by the SP-AMS in vacuum aerodynamic diameter (dva) varied from 100 nm to 450 nm dva, with most of the rBC mass below 200 dva. The NR-PMBC below 200 nm dva was primarily organic, whereas inorganics were generally found on larger rBC-containing particles. Positive matrix factorization analyses of both SP-AMS and HR-AMS data identified organic aerosol factors that were correlated in time but had different fragmentation patterns due to the different instruments vaporization techniques. Finally, we provide an overview of the volatility properties of NR-PMBC and report the presence of refractory oxygen species in some of the air masses encountered.

  13. Organic carbon in the sea surface microlayer and in submicron aerosol particles - measurements from the Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    van Pinxteren, Manuela; Wadinga Fomba, Kanneh; Müller, Konrad; Barthel, Stefan; von Tümpling, Wolf; Herrmann, Hartmut

    2016-04-01

    The export of organic compounds from the oceans can establish a considerable carbon flux in the Earth system. The detailed transport processes and especially the impact of environmental drivers in the organic carbon transfer are not yet fully understood. Here we present a broad study of measured dissolved organic carbon (DOC) and particulate organic carbon (POC) concentrations and enrichment in the sea surface microlayer (SML) as well as equivalent measurements in marine aerosol particles. For the first time, enrichment factors of organic carbon in marine ambient aerosol are reported that based on concerted measurements of seawater and aerosol particles. The measurements were conducted at different field campaigns in the Atlantic Ocean: at the Cape Verde islands, during two Atlantic transects with the RV Polarstern, and during a campaign at the Raune Fjord in Bergen, Norway. In oceanic water, concentration of DOC were in average 161 μmol/L in bulk water and 225 μmol/L in the SML. Average POC concentrations were 13 μmol/L in bulk water and 17 μmol/L in the SML. Instead of a constant enrichment of DOC or POC there are rather two pattern: high enrichment in samples with low concentrations and low enrichment when concentration were high. In seawater (bulk water and SML) small, mostly insignificant effects, concerning concentration and enrichment of DOC and POC were found regarding the impact of wind stress and chl-a concentrations. Differences between SML and bulk water concentrations are more pronounced at times of high chl-a, but all in all these effects are not strong. The thickness of the SML is affected by biological activity but probably caused by a more surface-active part of the DOC/POC pool and this is not reflected in the sum parameters. In the ambient marine aerosol particles water-soluble organic carbon (WSOC) and water-insoluble organic carbon (WISOC) concentrations were in average about 0.2 μg m-3, respectively. Higher concentration differences of

  14. Fluid dynamic studies on scattering aerosol and its generation for application as tracer particles in supersonic flow measurements utilizing laser Doppler velocimeter

    NASA Technical Reports Server (NTRS)

    Mazumder, M. K.; Hoyle, B. D.; Kirsch, K. J.

    1974-01-01

    An experimental study on the particle-fluid interactions of scattering aerosols was performed using monodisperse aerosols of different particle sizes for the application of laser Doppler velocimeters in subsonic turbulence measurements. Particle response was measured by subjecting the particles to an acoustically excited oscillatory fluid velocity field and by comparing the ratio of particle velocity amplitude to the fluid velocity amplitude as a function of particle size and the frequency of oscillation. Particle velocity was measured by using a differential laser Doppler velocimeter. The test aerosols were fairly monodisperse with a mean diameter that could be controlled over the size range from 0.1 to 1.0 micron. Experimental results on the generation of a fairly monodisperse aerosol of solid particles and liquid droplets and on the aerosol response in the frequency range 100 Hz to 100 kHz are presented. It is indicated that a unit density spherical scatterer of 0.3 micron-diameter would be an optimum choice as tracer particles for subsonic air turbulence measurements.

  15. Measurements of Extinction by Aerosol Particles Using Cavity Ring-Down Spectroscopy and Optical Feedback Cavity Ring-Down Spectroscopy

    NASA Astrophysics Data System (ADS)

    Mellon, Daniel; Kim, Jin; Orr-Ewing, Andrew J.

    2009-06-01

    Cavity ring-down spectroscopy and optical feedback cavity ring-down spectroscopy using continuous-wave distributed-feedback diode lasers around 1.6 μm and 400 nm have been used to measure the extinction of light by samples of monodisperse spherical aerosol particles < 1 μm in diameter. A statistical model is proposed to describe the linear relationship between the extinction coefficient (α) and its variance Var(α). Application of this model to experimental measurements of Var(α) for a range of (α) values typically below 2 × 10^{-6} cm^{-1} allows extinction cross sections for the aerosol particles to be obtained without need for knowledge of the particle number density. Samples of polystyrene spheres with diameters of 400 nm, 500 nm, 600 nm, 700 nm and 900 nm were used to test the model, by comparing extinction cross sections determined from the experiment with the predictions of Mie theory calculations. The fitting method used to extract decay constants, aggregation of particles and their cloud-like motion can all provide extra contributions to Var(α) and are understood with the aid of computer simulations. T.J.A. Butler, D. Mellon, J. Kim, J. Litman and A.J. Orr-Ewing J. Chem. Phys. A in press (2009)

  16. Airborne instruments to measure atmospheric aerosol particles, clouds and radiation: A cook's tour of mature and emerging technology

    NASA Astrophysics Data System (ADS)

    Baumgardner, D.; Brenguier, J. L.; Bucholtz, A.; Coe, H.; DeMott, P.; Garrett, T. J.; Gayet, J. F.; Hermann, M.; Heymsfield, A.; Korolev, A.; Krämer, M.; Petzold, A.; Strapp, W.; Pilewskie, P.; Taylor, J.; Twohy, C.; Wendisch, M.; Bachalo, W.; Chuang, P.

    2011-10-01

    An overview is presented of airborne systems for in situ measurements of aerosol particles, clouds and radiation that are currently in use on research aircraft around the world. Description of the technology is at a level sufficient for introducing the basic principles of operation and an extensive list of references for further reading is given. A number of newer instruments that implement emerging technology are described and the review concludes with a description of some of the most important measurement challenges that remain. This overview is a synthesis of material from a reference book that is currently in preparation and that will be published in 2012 by Wiley.

  17. LIDAR Measurements During Aerosols99

    NASA Technical Reports Server (NTRS)

    Voss, Kenneth J.; Welton, Ellsworth J.; Quinn, Patricia K.; Johnson, James; Thompson, Anne; Einaudi, Franco (Technical Monitor)

    2000-01-01

    The Aerosols99 cruise took place during the period from January 14, to February 8 1999 on the R/V Ron Brown. The cruise track was almost a straight line from Norfolk, Va. to Cape Town, South Africa and afforded the opportunity to sample several different aerosol regimes over the North and South Atlantic. A Micro Pulse LIDAR system was used continually during this cruise to profile the aerosol vertical structure. Inversions of this data illustrated a varying vertical structure depending on the dominant air mass. In clean maritime aerosols in the Northern and Southern Hemispheres the aerosols were capped at 1 km. When a Dust event from Africa was encountered the aerosol extinction increased its maximum height to above 2 km. During a period in which the air mass was dominated by biomass burning from Southern Africa, the aerosol layer extended to 4 km. Comparisons of the aerosol optical depth derived from LIDAR inversion and surface sunphotometers showed an agreement within +/- 0.05 RMS Similar comparisons between the extinction measured with a nephelometer and particle soot absorption photometer (at 19 m altitude) and the lowest LIDAR measurement (75 m) showed good agreement (+/- 0.014/km . The LIDAR underestimated surface extinction during periods when an elevated aerosol layer was present over a relatively clean surface layer, but otherwise gave accurate results.

  18. 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 ...

  19. 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 ...

  20. Hygroscopic growth of atmospheric aerosol particles based on active remote sensing and radiosounding measurements: selected cases in southeastern Spain

    NASA Astrophysics Data System (ADS)

    Granados-Muñoz, M. J.; Navas-Guzmán, F.; Bravo-Aranda, J. A.; Guerrero-Rascado, J. L.; Lyamani, H.; Valenzuela, A.; Titos, G.; Fernández-Gálvez, J.; Alados-Arboledas, L.

    2015-02-01

    A new methodology based on combining active and passive remote sensing and simultaneous and collocated radiosounding data to study the aerosol hygroscopic growth effects on the particle optical and microphysical properties is presented. The identification of hygroscopic growth situations combines the analysis of multispectral aerosol particle backscatter coefficient and particle linear depolarization ratio with thermodynamic profiling of the atmospheric column. We analyzed the hygroscopic growth effects on aerosol properties, namely the aerosol particle backscatter coefficient and the volume concentration profiles, using data gathered at Granada EARLINET station. Two study cases, corresponding to different aerosol loads and different aerosol types, are used for illustrating the potential of this methodology. Values of the aerosol particle backscatter coefficient enhancement factors range from 2.1 ± 0.8 to 3.9 ± 1.5, in the ranges of relative humidity 60-90 and 40-83%, being similar to those previously reported in the literature. Differences in the enhancement factor are directly linked to the composition of the atmospheric aerosol. The largest value of the aerosol particle backscatter coefficient enhancement factor corresponds to the presence of sulphate and marine particles that are more affected by hygroscopic growth. On the contrary, the lowest value of the enhancement factor corresponds to an aerosol mixture containing sulphates and slight traces of mineral dust. The Hänel parameterization is applied to these case studies, obtaining results within the range of values reported in previous studies, with values of the γ exponent of 0.56 ± 0.01 (for anthropogenic particles slightly influenced by mineral dust) and 1.07 ± 0.01 (for the situation dominated by anthropogenic particles), showing the convenience of this remote sensing approach for the study of hygroscopic effects of the atmospheric aerosol under ambient unperturbed conditions. For the first time

  1. Determination of the complex refractive indices of aerosol from aerodynamic particle size spectrometer and integrating nephelometer measurements.

    PubMed

    Han, Yong; Lü, Daren; Rao, Ruizhong; Wang, Yingjian

    2009-07-20

    An approach is developed to retrieve the complex index of refraction by coupling two well known instruments: an aerodynamic particle size spectrometer (APS) probe for measuring aerosol size distributions and an integrating nephelometer for measuring total light scattering coefficients. The retrieval is realized by an iterative least squares minimization of the fractional error between the nephelometer-measured light scattering coefficients and those calculated from the APS-measured size distributions based on the Mie theory for spherical particles. High-resolution data collected during two field experiments conducted at two locations with distinct environments in China are analyzed. The results show that light scattering coefficients, aerosol size distributions, and refractive indices all vary substantially with time. Further examination of their dependence on relative humidity suggests that instead of being monotonic change with relative humidity, the refractive index often fluctuates when the relative humidity changes. This nonmonotonic variation of refractive index with relative index suggests concurrent change of relative humidity and other chemical compositions. Possible errors in the retrieval are also discussed.

  2. Airborne Atmospheric Aerosol Measurement System

    NASA Astrophysics Data System (ADS)

    Ahn, K.; Park, Y.; Eun, H.; Lee, H.

    2015-12-01

    It is important to understand the atmospheric aerosols compositions and size distributions since they greatly affect the environment and human health. Particles in the convection layer have been a great concern in global climate changes. To understand these characteristics satellite, aircraft, and radio sonde measurement methods have usually been used. An aircraft aerosol sampling using a filter and/or impactor was the method commonly used (Jay, 2003). However, the flight speed particle sampling had some technical limitations (Hermann, 2001). Moreover, the flight legal limit, altitude, prohibited airspace, flight time, and cost was another demerit. To overcome some of these restrictions, Tethered Balloon Package System (T.B.P.S.) and Recoverable Sonde System(R.S.S.) were developed with a very light optical particle counter (OPC), impactor, and condensation particle counter (CPC). Not only does it collect and measure atmospheric aerosols depending on altitudes, but it also monitors the atmospheric conditions, temperature, humidity, wind velocity, pressure, GPS data, during the measurement (Eun, 2013). In this research, atmospheric aerosol measurement using T.B.P.S. in Ansan area is performed and the measurement results will be presented. The system can also be mounted to an unmanned aerial vehicle (UAV) and create an aerial particle concentration map. Finally, we will present measurement data using Tethered Balloon Package System (T.B.P.S.) and R.S.S (Recoverable Sonde System).

  3. Differentiation of hydrophobic from hydrophilic submicrometer aerosol particles

    SciTech Connect

    Juozaitis, A.; Ulevicius, V.; Girgzdys, A. ); Willeke, K. )

    1993-02-01

    A method has been developed that differentiates hydrophobic from hydrophilic submicrometer aerosol particles in air environments containing polydisperse aerosols composed of different chemical species. First, a narrow particle size range is extracted from the polydisperse aerosol by an electrostatic aerosol classifier. Then the monodisperse aerosols of different origins are exposed to preselected supersaturation levels and are size-classified again by a second electrostatic classifier. Hydrophobic aerosol particles pass through the second classifier when its size window matches that of the first classifier. Hydrophilic aerosol particles grow to a larger size and are removed by the second classifier. The method has been applied in the field by measuring the fraction of hydrophobic atmospheric particles in a suburb of Vilnius, Lithuania, during a period of high emission of hydrophobic soot particles from residential coal and industrial oil burning in winter. 33 refs., 4 figs.

  4. Laboratory measurements of the angular light-scattering properties of internally mixed organic and sea-salt aerosol particles using polar nephelometry

    NASA Astrophysics Data System (ADS)

    Curtis, D. B.; Tinilau, S. S.

    2013-12-01

    Aerosol particles play an important, but relatively poorly understood, role in Earth's climate. Sea-salt aerosol is one of the most prevalent naturally occurring aerosols and is therefore expected to have a large effect on climate by scattering incoming solar radiation back to space. While sea-salt aerosol has been thought to be mainly composed of sodium chloride and other salts, measurements have shown the presence of biogenic organic compounds, such as glucose, in primary sea-salt aerosol particles. In addition, the sea-salt aerosol particles can become coated by secondary organics from anthropogenic activities. In order to better understand the potential climate effects of internally mixed organic and sea-salt particles, the angular scattering properties of laboratory-generated aerosols were measured at a wavelength of 532 nm using polar nephelometry. The polar nephelometer collected scattered light with an elliptical mirror and focused it across a linear CCD detector. The instrument was therefore capable of measuring the scattering intensity as a function of scattering angle (the phase function). Two incident polarizations were studied, parallel and perpendicular to the scattering plane, which were then used to calculate the degree of linear polarization. The scattering measurements along with size distribution measurements were used to retrieve the refractive index of the particles by comparison with Mie theory. Particles were generated from solutions of sodium chloride with varying concentrations of organics such as glucose and oxalic acid. In addition, particles generated from authentic sea-water were studied for comparison. Preliminary results indicate that the effective refractive indices of the mixed particles differ significantly from pure sodium chloride and do not follow simple mixing rules used to calculate refractive index from individual components.

  5. Laboratory measurements of the angular light-scattering properties of internally mixed organic and sea-salt aerosol particles using polar nephelometry

    NASA Astrophysics Data System (ADS)

    Cai, C.; Kelly, J. T.; Kaduwela, A.; Avise, J. C.; Jackson, B. S.; Yin, D.; Gurer, K.; Baker, K.; Oetjen, H.; Baidar, S.; Volkamer, R.; Ryerson, T. B.; Pollack, I. B.; Holloway, J. S.; Gilman, J. B.; Kuster, W. C.; Warneke, C.; De Gouw, J. A.; Lefer, B. L.; Alvarez, S. L.; Rappenglueck, B.; Markovic, M. Z.; VandenBoer, T. C.; Murphy, J. G.; Weber, R.; Guha, A.; Gentner, D. R.; Goldstein, A. H.; McCauley, E.; Parrish, D. D.

    2011-12-01

    Aerosol particles play an important, but relatively poorly understood, role in Earth's climate. Sea-salt aerosol is one of the most prevalent naturally occurring aerosols and is therefore expected to have a large effect on climate by scattering incoming solar radiation back to space. While sea-salt aerosol has been thought to be mainly composed of sodium chloride and other salts, measurements have shown the presence of biogenic organic compounds, such as glucose, in primary sea-salt aerosol particles. In addition, the sea-salt aerosol particles can become coated by secondary organics from anthropogenic activities. In order to better understand the potential climate effects of internally mixed organic and sea-salt particles, the angular scattering properties of laboratory-generated aerosols were measured at a wavelength of 532 nm using polar nephelometry. The polar nephelometer collected scattered light with an elliptical mirror and focused it across a linear CCD detector. The instrument was therefore capable of measuring the scattering intensity as a function of scattering angle (the phase function). Two incident polarizations were studied, parallel and perpendicular to the scattering plane, which were then used to calculate the degree of linear polarization. The scattering measurements along with size distribution measurements were used to retrieve the refractive index of the particles by comparison with Mie theory. Particles were generated from solutions of sodium chloride with varying concentrations of organics such as glucose and oxalic acid. In addition, particles generated from authentic sea-water were studied for comparison. Preliminary results indicate that the effective refractive indices of the mixed particles differ significantly from pure sodium chloride and do not follow simple mixing rules used to calculate refractive index from individual components.

  6. Airborne measurements of cloud-forming nuclei and aerosol particles in stabilized ground clouds produced by solid rocket booster firings

    NASA Technical Reports Server (NTRS)

    Hindman, E. E., II; Ala, G. G.; Parungo, F. P.; Willis, P. T.; Bendura, R. J.; Woods, D.

    1978-01-01

    Airborne measurements of cloud volumes, ice nuclei and cloud condensation nuclei, liquid particles, and aerosol particles were obtained from stabilized ground clouds (SGCs) produced by Titan 3 launches at Kennedy Space Center, 20 August and 5 September 1977. The SGCs were bright, white, cumulus clouds early in their life and contained up to 3.5 g/m3 of liquid in micron to millimeter size droplets. The measured cloud volumes were 40 to 60 cu km five hours after launch. The SGCs contained high concentrations of cloud condensation nuclei active at 0.2%, 0.5%, and 1.0% supersaturation for periods of three to five hours. The SGCs also contained high concentrations of submicron particles. Three modes existed in the particle population: a 0.05 to 0.1 micron mode composed of aluminum-containing particles, a 0.2 to 0.8 micron mode, and a 2.0 to 10 micron mode composed of particles that contained primarily aluminum.

  7. Performance of a focused cavity aerosol spectrometer for measurements in the stratosphere of particle size in the 0.06-2.0-micrometer-diameter range

    NASA Technical Reports Server (NTRS)

    Jonsson, H. H.; Wilson, J. C.; Brock, C. A.; Knollenberg, R. G.; Newton, R.; Dye, J. E.; Baumgardner, D.; Borrmann, S.; Ferry, G. V.; Pueschel, R.

    1995-01-01

    A focused cavity aerosol spectrometer aboard a NASA ER-2 high-altitude aircraft provided high-resolution measurements of the size of the stratospheric particles in the 0.06-2.0-micrometer-diameter range in flights following the eruption of Mount Pinatubo in 1991. Effects of anisokinetic sampling and evaporation in the sampling system were accounted for by means adapted and specifically developed for this instrument. Calibrations with monodisperse aerosol particles provided the instrument's response matrix, which upon inversion during data reduction yielded the particle size distributions. The resultant dataset is internally consistent and generally shows agreement to within a factor of 2 with comparable measurements simultaneously obtained by a condensation nuclei counter, a forward-scattering spectrometer probe, and aerosol particle impactors, as well as with nearby extinction profiles obtained by satellite measurements and with lidar measurements of backscatter.

  8. Airborne Coarse Mode Aerosol Measurements with the CAS-DPOL Instrument: Effects of Particle Shape and Refractive Index and Implications for Radiative Transfer Estimate

    NASA Astrophysics Data System (ADS)

    Sauer, D. N.; Weinzierl, B.; Gasteiger, J.; Spanu, A.; Freudenthaler, V.; Gross, S.

    2015-12-01

    Each year huge amounts of mineral dust are mobilized in deserts and arid regions of the world and transported over large distances forming thick elevated aerosol layers with a substantial fraction of coarse mode particles. Optical properties of mineral dust, including the absorptive refractive index of some components, cause a significant effect on the atmospheric radiative energy balance from optical to infrared wavelengths. The aerosol characteristics, in particular its coarse mode size distribution, are modified during long-range transport by aging and deposition processes. This also affects the aerosol optical properties and therefore the effect on the atmospheric radiative energy budget. In-situ measurements of aerosol microphysical properties are essential to characterize those effects in order to be implemented in global climate models in parametrized form. However, in-situ measurements of airborne coarse mode aerosols such as mineral dust and volcanic ash are challenging and the measurements are usually affected by substantial uncertainties. In this work we use airborne measurements of mineral dust from our optical light-scattering spectrometer CAS-DPOL during SALTRACE 2013 to discuss the analysis of such data. We cover the effects of varying refractive index and particle shapes and develop recommendations for the configuration of the CAS-DPOL for aerosol studies. We also present an inversion method to derive coarse mode size distributions from light-scattering probes for mixtures of non-spherical, absorbing aerosols. The size distributions retrieved from the in-situ measurements are then validated using an independent analysis with a combination of sun-photometer and lidar data. We apply these methods to investigate the Saharan mineral dust particle size distributions measured on both sides of the Atlantic Ocean and discuss the influence of aerosol aging on the atmospheric radiative energy budget. With this example we also assess how the uncertainties

  9. Measurements of aerosol-cloud interactions, including on-line particle chemical composition, at the Jungfraujoch Global Atmospheric Watch Station

    NASA Astrophysics Data System (ADS)

    Coe, H.; Allan, J. D.; Alfarra, M. R.; Williams, P. I.; Bower, K. N.; Gallagher, M. W.; Choularton, T. W.; Weingartner, E.; Corrigan, C.; Baltensperger, U.

    2003-04-01

    The Global Atmospheric Watch research laboratory is located in the Sphinx building, 3580 m asl; 46.55oN, 7.98oE on the Jungfraujoch in the Swiss Alps. The site is exposed to a wide range of conditions and frequently samples long range transported lower free tropospheric air, and is exposed to cloudy conditions. The Paul Scherrer Institute have previously developed a dual inlet system that allows measurements of the total sub-micron aerosol population (dry residuals and interstitial particles) and interstitial particles alone to be made alternately every few minutes. During July 2002 an Aerodyne Aerosol Mass Spectrometer was coupled to the dual inlet and was used to sample the composition of both the total particle distribution and the interstitial fraction and hence derive the mass loadings of the dry droplet residuals. In out of cloud conditions the aerosol composition can be linked to air mass history and age of the air mass. Microphysical measurements include cloud droplet size distributions made using an FSSP and also a new phase Doppler anemometry system. A comparison between these probes will be made. Two different types of cloud droplet spectra were observed. In the first type a large number of cloud droplets were measured with a single, narrow drop size distribution and modal diameter of around 10 um. In the second type, a bimodal cloud droplet spectrum occurred with a smaller mode (by number) at around 20 um, in addition to the 10 um mode. The aerosol mass spectrometry shows that the composition of the residuals from the two spectrum types is very different, the former type being composed mainly of sulphate, the latter a combination of nitrate, sulphate and organic material. We have also shown that the organic material observed is highly oxidized. We argue that the bimodality arises as a result of mixing of cloud droplets below the site that have been activated separately: the larger a less numerous mode in the widespread strato-cumulus forming under low

  10. Fluorescent biological aerosol particle measurements at a tropical high-altitude site in southern India during the southwest monsoon season

    NASA Astrophysics Data System (ADS)

    Valsan, A. E.; Ravikrishna, R.; Biju, C. V.; Pöhlker, C.; Després, V. R.; Huffman, J. A.; Pöschl, U.; Gunthe, S. S.

    2016-08-01

    An ultraviolet aerodynamic particle sizer (UV-APS) was continuously operated for the first time during two seasons to sample the contrasting winds during monsoon and winter to characterize the properties of fluorescent biological aerosol particles (FBAPs), at a high-altitude site in India. Averaged over the entire monsoon campaign (1 June-21 August 2014), the arithmetic mean number and mass concentrations of coarse-mode (> 1 µm) FBAPs were 0.02 cm-3 and 0.24 µg m-3, respectively, which corresponded to ˜ 2 and 6 % of total aerosol loading, respectively. Average FBAP number size distribution exhibited a peak at ˜ 3 µm, which is attributed to the fungal spores, as supported by scanning electron microscope (SEM) images, and these results are consistent with previous studies made for FBAPs. During 11 weeks of measurements the variability of the total coarse-mode particle number (TAP) concentration was high compared to that observed in FBAP number concentrations. The TAP and FBAP number concentrations measured at this site were strongly dependent on changes in wind direction and rainfall. During periods of westerly/southwesterly winds with heavy persistent rainfall, the TAP and FBAP concentrations exhibited very low values (1.3 and 0.005 cm-3, respectively) with no significant diurnal variations, whereas during periods of northerly winds with scattered rainfall FBAPs exhibited relatively high concentration values (0.05 cm-3) with pronounced diurnal variations, which were strongly coupled with diurnal variations in meteorological parameters. The campaign-averaged FBAP number concentrations were shown to correlate with daily patterns of meteorological parameters and were positively correlated with relative humidity (RH; R2 = 0.58) and negatively with temperature (R2 = 0.60) and wind speed (R2 = 0.60). We did not observe any significant positive correlation with precipitation as reported by previous researchers from selected areas. These measurement results confirm the

  11. Aerosols in the tropical and subtropical UT/LS: in-situ measurements of submicron particle abundance and volatility

    NASA Astrophysics Data System (ADS)

    Borrmann, S.; Kunkel, D.; Weigel, R.; Minikin, A.; Deshler, T.; Wilson, J. C.; Curtius, J.; Shur, G. N.; Belyaev, G. V.; Law, K. S.; Cairo, F.

    2009-11-01

    Processes occurring in the tropical upper troposphere and lower stratosphere (UT/LS) are of importance for the global climate, for the stratospheric dynamics and air chemistry, and they influence the global distribution of water vapour, trace gases and aerosols. The mechanisms underlying cloud formation and variability in the UT/LS are of scientific concern as these still are not adequately described and quantified by numerical models. Part of the reasons for this is the scarcity of detailed in-situ measurements in particular from the Tropical Transition Layer (TTL) within the UT/LS. In this contribution we provide measurements of particle number densities and the amounts of non-volatile particles in the submicron size range present in the UT/LS over Southern Brazil, West Africa, and Northern Australia. The data were collected in-situ on board of the Russian high altitude research aircraft M-55 "Geophysica" using the specialised COPAS (COndensation PArticle counting System) instrument during the TROCCINOX (Araçatuba, Brazil, February 2005), the SCOUT-O3 (Darwin, Australia, December 2005), and SCOUT-AMMA (Ouagadougou, Burkina Faso, August 2006) campaigns. The vertical profiles obtained are compared to those from previous measurements from the NASA DC-8 and NASA WB-57F over Costa Rica and other tropical locations between 1999 and 2007. The number density of the submicron particles as function of altitude was found to be remarkably constant (even back to 1987) over the tropical UT/LS altitude band such that a parameterisation suitable for models can be extracted from the measurements. At altitudes corresponding to potential temperatures above 430 K a slight increase of the number densities from 2005/2006 results from the data in comparison to the 1987 to 2007 measurements. The origins of this increase are unknown. By contrast the data from Northern hemispheric mid latitudes do not exhibit such an increase between 1999 and 2006. Vertical profiles of the non

  12. Development of an H-TDMA for long-term unattended measurement of the hygroscopic properties of atmospheric aerosol particles

    NASA Astrophysics Data System (ADS)

    Nilsson, E.; Swietlicki, E.; Sjogren, S.; Löndahl, J.; Nyman, M.; Svenningsson, B.

    2009-04-01

    A new hygroscopic tandem differential mobility analyzer (H-TDMA) has been constructed at Lund University within the frameworks of the EU FP6 Infrastructure Project EUSAAR (http://www.eusaar.org/). The aim of this coordinated H-TDMA development is to design and evaluate a new generation of H-TDMAs that are capable of conducting long term measurements of the hygroscopic growth and state of mixing of sub-micrometer atmospheric aerosol particles at the EUSAAR aerosol super-sites across Europe. The H-TDMA constructed for this project has been validated with respect to hygroscopic growth factor, stability of relative humidity (RH), temperature stability and its ability to operate unattended for longer periods of time. When measuring growth factors of ammonium sulphate, the new H-TDMA system was found to measure within a growth factor deviation of ±0.05 compared to previously recorded data by Tang et al. (1994). The long term RH of the system has been found stable at 90.0% with a standard deviation of ±0.23% and an average temperature variability of the second DMA less than ±0.1 K. Daily automated ammonium sulphate measurements have validated the ambient measurements. The instrument is operated at the EMEP/EUSAAR background station Vavihill in the southern part of Sweden.

  13. Development of an H-TDMA for long-term unattended measurement of the hygroscopic properties of atmospheric aerosol particles

    NASA Astrophysics Data System (ADS)

    Nilsson, E.; Swietlicki, E.; Sjogren, S.; Löndahl, J.; Nyman, M.; Svenningsson, B.

    2009-06-01

    A new hygroscopic tandem differential mobility analyzer (H-TDMA) has been constructed at Lund University within the frameworks of the EU FP6 Infrastructure Project EUSAAR (http://www.eusaar.org/). The aim of this coordinated H-TDMA development is to design and evaluate a new generation of H-TDMAs that are capable of conducting long term measurements of the hygroscopic growth and state of mixing of sub-micrometer atmospheric aerosol particles at the EUSAAR aerosol super-sites across Europe. The H-TDMA constructed for this project has been validated with respect to hygroscopic growth factor, stability of relative humidity (RH), temperature stability and its ability to operate unattended for longer periods of time. When measuring growth factors of ammonium sulphate, the new H-TDMA system was found to measure within a growth factor deviation of ±0.05 compared to previously recorded data by Tang et al. (1994). The long term RH of the system has been found stable at 90.0% with a standard deviation of ±0.23% and an average temperature variability of the second DMA less than ±0.1 K. Daily automated ammonium sulphate measurements have validated the ambient measurements. The instrument is operated at the EMEP/EUSAAR background station Vavihill in the southern part of Sweden.

  14. Single-Particle Measurements of Midlatitude Black Carbon and Light-Scattering Aerosols from the Boundary Layer to the Lower Stratosphere

    NASA Technical Reports Server (NTRS)

    Schwartz, J. P.; Gao, R. S.; Fahey, D. W.; Thomson, D. S.; Watts, L. A.; Wilson, J. C.; Reeves, J. M.; Darbeheshti, M.; Baumgardner, D. G.; Kok, G. L.; Chung, S. H.; Schulz, M.; Hendricks, J.; Lauer, A.; Kaercher, B.; Slowik, J. G.; Rosenlof, K. H.; Thompson, T. L.; Langford, A. O.; Loewenstein, M.; Aikin, K. C.

    2006-01-01

    A single-particle soot photometer (SP2) was flown on a NASA WB-57F high-altitude research aircraft in November 2004 from Houston, Texas. The SP2 uses laser-induced incandescence to detect individual black carbon (BC) particles in an air sample in the mass range of approx.3-300 fg (approx.0.15-0.7 microns volume equivalent diameter). Scattered light is used to size the remaining non-BC aerosols in the range of approx.0.17-0.7 microns diameter. We present profiles of both aerosol types from the boundary layer to the lower stratosphere from two midlatitude flights. Results for total aerosol amounts in the size range detected by the SP2 are in good agreement with typical particle spectrometer measurements in the same region. All ambient incandescing particles were identified as BC because their incandescence properties matched those of laboratory-generated BC aerosol. Approximately 40% of these BC particles showed evidence of internal mixing (e.g., coating). Throughout profiles between 5 and 18.7 km, BC particles were less than a few percent of total aerosol number, and black carbon aerosol (BCA) mass mixing ratio showed a constant gradient with altitude above 5 km. SP2 data was compared to results from the ECHAM4/MADE and LmDzT-INCA global aerosol models. The comparison will help resolve the important systematic differences in model aerosol processes that determine BCA loadings. Further intercomparisons of models and measurements as presented here will improve the accuracy of the radiative forcing contribution from BCA.

  15. Single-Particle Measurements of Midlatitude Black Carbon and Light-Scattering Aerosols from the Boundary Layer to the Lower Stratosphere

    NASA Technical Reports Server (NTRS)

    Schwartz, J. P.; Gao, R. S.; Fahey, D. W.; Thomson, D. S.; Watts, L. A.; Wilson, J. C.; Reeves, J. M.; Darbeheshti, M.; Baumgardner, D. G.; Kok, G. L.; hide

    2006-01-01

    A single-particle soot photometer (SP2) was flown on a NASA WB-57F high-altitude research aircraft in November 2004 from Houston, Texas. The SP2 uses laser-induced incandescence to detect individual black carbon (BC) particles in an air sample in the mass range of approx.3-300 fg (approx.0.15-0.7 microns volume equivalent diameter). Scattered light is used to size the remaining non-BC aerosols in the range of approx.0.17-0.7 microns diameter. We present profiles of both aerosol types from the boundary layer to the lower stratosphere from two midlatitude flights. Results for total aerosol amounts in the size range detected by the SP2 are in good agreement with typical particle spectrometer measurements in the same region. All ambient incandescing particles were identified as BC because their incandescence properties matched those of laboratory-generated BC aerosol. Approximately 40% of these BC particles showed evidence of internal mixing (e.g., coating). Throughout profiles between 5 and 18.7 km, BC particles were less than a few percent of total aerosol number, and black carbon aerosol (BCA) mass mixing ratio showed a constant gradient with altitude above 5 km. SP2 data was compared to results from the ECHAM4/MADE and LmDzT-INCA global aerosol models. The comparison will help resolve the important systematic differences in model aerosol processes that determine BCA loadings. Further intercomparisons of models and measurements as presented here will improve the accuracy of the radiative forcing contribution from BCA.

  16. Ambient measurements of biological aerosol particles near Killarney, Ireland: a comparison between real-time fluorescence and microscopy techniques

    NASA Astrophysics Data System (ADS)

    Healy, D. A.; Huffman, J. A.; O'Connor, D. J.; Pöhlker, C.; Pöschl, U.; Sodeau, J. R.

    2014-08-01

    Primary biological aerosol particles (PBAPs) can contribute significantly to the coarse particle burden in many environments. PBAPs can thus influence climate and precipitation systems as cloud nuclei and can spread disease to humans, animals, and plants. Measurement data and techniques for PBAPs in natural environments at high time- and size resolution are, however, sparse, and so large uncertainties remain in the role that biological particles play in the Earth system. In this study two commercial real-time fluorescence particle sensors and a Sporewatch single-stage particle impactor were operated continuously from 2 August to 2 September 2010 at a rural sampling location in Killarney National Park in southwestern Ireland. A cascade impactor was operated periodically to collect size-resolved particles during exemplary periods. Here we report the first ambient comparison of a waveband integrated bioaerosol sensor (WIBS-4) with a ultraviolet aerodynamic particle sizer (UV-APS) and also compare these real-time fluorescence techniques with results of fluorescence and optical microscopy of impacted samples. Both real-time instruments showed qualitatively similar behavior, with increased fluorescent bioparticle concentrations at night, when relative humidity was highest and temperature was lowest. The fluorescent particle number from the FL3 channel of the WIBS-4 and from the UV-APS were strongly correlated and dominated by a 3 μm mode in the particle size distribution. The WIBS FL2 channel exhibited particle modes at approx. 1 and 3 μm, and each was correlated with the concentration of fungal spores commonly observed in air samples collected at the site (ascospores, basidiospores, Ganoderma spp.). The WIBS FL1 channel exhibited variable multimodal distributions turning into a broad featureless single mode after averaging, and exhibited poor correlation with fungal spore concentrations, which may be due to the detection of bacterial and non-biological fluorescent

  17. Ambient measurements of biological aerosol particles near Killarney, Ireland: a comparison between real-time fluorescence and microscopy techniques

    NASA Astrophysics Data System (ADS)

    Healy, D. A.; Huffman, J. A.; O'Connor, D. J.; Pöhlker, C.; Pöschl, U.; Sodeau, J. R.

    2014-02-01

    Primary biological aerosol particles (PBAP) can contribute significantly to the coarse particle burden in many environments, may thus influence climate and precipitation systems as cloud nuclei, and can spread disease to humans, animals, and plants. Measurements of PBAP in natural environments taken at high time- and size- resolution are, however, sparse and so large uncertainties remain in the role that biological particles play in the Earth system. In this study two commercial real-time fluorescence particle sensors and a Sporewatch single-stage particle impactor were operated continuously from 2 August to 2 September 2010 at a rural sampling location in Killarney National Park in south western Ireland. A cascade impactor was operated periodically to collect size-resolved particles during exemplary periods. Here we report the first ambient comparison of the waveband integrated bioaerosol sensor (WIBS-4) with the ultraviolet aerodynamic particle sizer (UV-APS) and also compare these real-time fluorescence techniques with results of fluorescence and optical microscopy of impacted samples. Both real-time instruments showed qualitatively similar behaviour, with increased fluorescent bioparticle concentrations at night when relative humidity was highest and temperature was lowest. The fluorescent particle number from the FL3 channel of the WIBS-4 and from the UV-APS were strongly correlated and dominated by a 3 μm mode in the particle size distribution. The WIBS FL2 channel exhibited particle modes at approx. 1 and 3 μm, and each were correlated with the concentration of fungal spores commonly observed in air samples collected at the site (ascospores, basidiospores, Ganoderma spp.). The WIBS FL1 channel exhibited variable multi-modal distributions turning into a broad featureless single mode after averaging and exhibited poor correlation with fungal spore concentrations, which may be due to the detection of bacterial and non-biological fluorescent particles

  18. Aerosol particle analysis by Raman scattering technique

    SciTech Connect

    Fung, K.H.; Tang, I.N.

    1992-10-01

    Laser Raman spectroscopy is a very versatile tool for chemical characterization of micron-sized particles. Such particles are abundant in nature, and in numerous energy-related processes. In order to elucidate the formation mechanisms and understand the subsequent chemical transformation under a variety of reaction conditions, it is imperative to develop analytical measurement techniques for in situ monitoring of these suspended particles. In this report, we outline our recent work on spontaneous Raman, resonance Raman and non-linear Raman scattering as a novel technique for chemical analysis of aerosol particles as well as supersaturated solution droplets.

  19. 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.

  20. Measuring the emission rate of an aerosol source placed in a ventilated room using a tracer gas: influence of particle wall deposition.

    PubMed

    Bémer, D; Lecler, M T; Régnier, R; Hecht, G; Gerber, J M

    2002-04-01

    A method to measure the emission rate of an airborne pollutant source using a tracer gas was tested in the case of an aerosol source. The influence of particle deposition on the walls of a test room of 72 m3 was studied. The deposition rate of an aerosol of MgCl2 was determined by means of two methods: one based on measuring the aerosol concentration decay inside the ventilated room, the other based on calculation of the material mass balance. The concentration decay was monitored by optical counting and the aerosol mass concentration determined by means of sampling on a filter and analysis of the mass deposited by atomic absorption spectrometry. Four series of measurements were carried out. The curve giving the deposition rate according to the particle aerodynamic diameter (d(ae)) was established and shows deposition rates higher than those predicted using the model of Corner. The decay method gives the best results. The study carried out has shown that the phenomenon of deposition has little effect on the measurement of the aerosol source emission rate using a tracer gas for particles of aerodynamic diameter < 5 microm (underestimation < 25%). For particles of a greater diameter, wall deposition is an extremely limiting factor for the method, the influence of which can, however, be limited by using a test booth of small volume and keeping the sampling duration as short as possible.

  1. Arctic organic aerosol measurements show particles from mixed combustion in spring haze and from frost flowers in winter

    NASA Astrophysics Data System (ADS)

    Shaw, P. M.; Russell, L. M.; Jefferson, A.; Quinn, P. K.

    2010-05-01

    Submicron atmospheric aerosol particles were collected between 1 March 2008 and 1 March 2009 at Barrow, Alaska, to characterize the organic mass (OM) in the Arctic aerosol. Organic functional group concentrations and trace metals were measured with FTIR on submicron particles collected on Teflon filters. The OM varied from 0.07 μg m-3 in summer to 0.43 μg m-3 in winter, and 0.35 μg m-3 in spring, showing a transition in OM composition between spring and winter. Most of the OM in spring could be attributed to anthropogenic sources, consisting primarily of alkane and carboxylic acid functional groups and correlated to elemental tracers of industrial pollution, biomass burning, and shipping emissions. PMF analysis associated OM with two factors, a Mixed Combustion factor (MCF) and an Ocean-derived factor (ODF). Back trajectory analysis revealed that the highest fractions of the MCF were associated with air masses that had originated from northeastern Asia and the shipping lanes south of the Bering Straits. The ODF consisted of organic hydroxyl groups and correlated with organic and inorganic seawater components. The ODF accounted for more than 55% of OM in winter when the sampled air masses originated along the coastal and lake regions of the Northwest Territories of Canada. Frost flowers with organic-salt coatings that arise by brine rejection during sea ice formation may account for this large source of carbohydrate-like OM during the ice-covered winter season. While the anthropogenic sources contributed more than 0.3 μg m-3 of the springtime haze OM, ocean-derived particles provided comparable OM sources in winter.

  2. Slip Correction Measurements of Polystyrene and Polyvinyltoluene Aerosol Particles Using AN Improved Millikan Apparatus.

    NASA Astrophysics Data System (ADS)

    Allen, Michael Dana

    A slip correction equation of the form C(Kn) = 1 + Kn{(alpha) + (beta)exp(-(gamma)/Kn)} with Kn the particle Knudsen number is routinely used to correct Stokes' law for progressively lower than predicted drag force as Kn increases. The published values of the parameters ((alpha), (beta), and (gamma)) are based on Millikan's original values corrected with an improved value of mean free path for gas molecules in dry air. In this work, Millikan's most accurate raw data were carefully reviewed and the slip correction parameters were reevaluated using the latest published values of physical constants and nonlinear least squares function fitting. The values of (alpha), (beta), and (gamma) given by Millikan in 1923 adjusted for a modern value of the mean free path ((lamda) = 0.0673 (mu)m at 23(DEGREES)C and 760 mm of Hg) were 1.209, 0.406, and 0.893, respectively. Improved values of these parameters calculated by least squares using Millikan's most accurate raw data are 1.155, 0.471, and 0.596, respectively. Though these two sets of values appear significantly different, the maximum percentage difference in the calculated correction factor is less than 2.0% over the Knudsen number range of 0.001 to 100. This error is small when compared to differences which may be caused by different particle surfaces and gas compositions. An improved version of the Millikan oil-drop apparatus was built and slip correction measurements were made on ninety solid, spherical particles in air. Measurements were made on eleven polystyrene latex-divinylbenzene particles, twenty-five polyvinyltoluene particles, and fifty-four polystyrene latex particles, spanning a Knudsen number range from 0.03 to 7.2. The values of (alpha), (beta), and (gamma) computed using nonlinear least squares function fitting for a mean free path at 23(DEGREES)C of 0.0673 (mu)m and a viscosity of 1.83245 x 10('-4) gcm('-1)s(' -1) were 1.142, 0.558, and 0.99 respectively. The value of (alpha) agrees very closely with

  3. Calcium enrichment in sea spray aerosol particles

    NASA Astrophysics Data System (ADS)

    Salter, M. E.; Hamacher-Barth, E.; Leck, C.; Werner, J.; Johnson, C. M.; Riipinen, I.; Nilsson, E. D.; Zieger, P.

    2016-08-01

    Sea spray aerosol particles are an integral part of the Earth's radiation budget. To date, the inorganic composition of nascent sea spray aerosol particles has widely been assumed to be equivalent to the inorganic composition of seawater. Here we challenge this assumption using a laboratory sea spray chamber containing both natural and artificial seawater, as well as with ambient aerosol samples collected over the central Arctic Ocean during summer. We observe significant enrichment of calcium in submicrometer (<1 μm in diameter) sea spray aerosol particles when particles are generated from both seawater sources in the laboratory as well as in the ambient aerosols samples. We also observe a tendency for increasing calcium enrichment with decreasing particle size. Our results suggest that calcium enrichment in sea spray aerosol particles may be environmentally significant with implications for our understanding of sea spray aerosol, its impact on Earth's climate, as well as the chemistry of the marine atmosphere.

  4. A Miniature Aerosol Sensor for Detecting Polydisperse Airborne Ultrafine Particles.

    PubMed

    Zhang, Chao; Wang, Dingqu; Zhu, Rong; Yang, Wenming; Jiang, Peng

    2017-04-22

    Counting and sizing of polydisperse airborne nanoparticles have attracted most attentions owing to increasing widespread presence of airborne engineered nanoparticles or ultrafine particles. Here we report a miniature aerosol sensor to detect particle size distribution of polydisperse ultrafine particles based on ion diffusion charging and electrical detection. The aerosol sensor comprises a couple of planar electrodes printed on two circuit boards assembled in parallel, where charging, precipitation and measurement sections are integrated into one chip, which can detect aerosol particle size in of 30-500 nm, number concentration in range of 5 × 10²-10⁷ /cm³. The average relative errors of the measured aerosol number concentration and the particle size are estimated to be 12.2% and 13.5% respectively. A novel measurement scheme is proposed to actualize a real-time detection of polydisperse particles by successively modulating the measurement voltage and deducing the particle size distribution through a smart data fusion algorithm. The effectiveness of the aerosol sensor is experimentally demonstrated via measurements of polystyrene latex (PSL) aerosol and nucleic acid aerosol, as well as sodium chloride aerosol particles.

  5. AEROSOL PARTICLE COLLECTOR DESIGN STUDY

    SciTech Connect

    Lee, S; Richard Dimenna, R

    2007-09-27

    A computational evaluation of a particle collector design was performed to evaluate the behavior of aerosol particles in a fast flowing gas stream. The objective of the work was to improve the collection efficiency of the device while maintaining a minimum specified air throughput, nominal collector size, and minimal power requirements. The impact of a range of parameters was considered subject to constraints on gas flow rate, overall collector dimensions, and power limitations. Potential improvements were identified, some of which have already been implemented. Other more complex changes were identified and are described here for further consideration. In addition, fruitful areas for further study are proposed.

  6. Phase transition behaviour of sodium oleate aerosol particles

    NASA Astrophysics Data System (ADS)

    Nájera, Juan J.

    Field measurements have shown that organic surfactants are significant components of atmospheric aerosols. While fatty acids, among other surfactants, are prevalent in the atmosphere, the influence of these species on the chemical and physical properties of atmospheric aerosols remains not fully characterized. In order to assess the phase in which particles may exist, a detailed study of the deliquescence of a model surfactant aerosol has been carried out. Sodium oleate was chosen as a surfactant proxy relevant in atmospheric aerosol. Sodium oleate micelle aerosol particles were generated nebulizing a sodium oleate aqueous solution. In this study, the water uptake and phase transition of sodium oleate aerosol particles have been studied in a room temperature aerosol flow tube system (AFT) using Fourier transform infrared (FTIR) spectroscopy. Aerosol morphology and elemental composition were also analysed using scanning electron microscopy/energy dispersive X-ray analysis (SEM/EDX) techniques. The particles are homogeneously distributed as ellipsoidal-shape aggregates of micelles particles with an average size of ˜1.1 μm. The deliquescence by the sodium oleate aerosol particles was monitored by infrared extinction spectroscopy, where the dried aerosol particles were exposed to increasing relative humidity as they passed through the AFT. Observations of the infrared absorption features of condensed phase liquid water enable to determine the sodium oleate deliquescence phase transition at 88±2%.

  7. Aerosol properties, source identification, and cloud processing in orographic clouds measured by single particle mass spectrometry on a Central European mountain site during HCCT-2010

    NASA Astrophysics Data System (ADS)

    Roth, A.; Schneider, J.; Klimach, T.; Mertes, S.; van Pinxteren, D.; Herrmann, H.; Borrmann, S.

    2015-09-01

    Cloud residues and out-of-cloud aerosol particles with diameters between 150 and 900 nm have been analysed by on-line single particle aerosol mass spectrometry during the six-week study HCCT-2010 in September/October 2010. The measurement location was the mountain Schmücke (937 m a.s.l.) in Central Germany. More than 170 000 bipolar mass spectra from out-of-cloud aerosol particles and more than 14 000 bipolar mass spectra from cloud residual particles were obtained and were classified using a fuzzy c-means clustering algorithm. Analysis of the uncertainty of the sorting algorithm was conducted on a subset of the data by comparing the clustering output with particle-by-particle inspection and classification by the operator. This analysis yielded a false classification probability between 13 and 48 %. Additionally, particle types were identified by specific marker ions. The results from the ambient aerosol analysis show that 63 % of the analysed particles belong to clusters indicating a diurnal variation, suggesting that local or regional sources dominate the aerosol, especially for particles containing soot and biomass burning particles. In the cloud residues the relative percentage of large soot-containing particles and particles containing amines was found to be increased compared to the out-of-cloud aerosol, while in general organic particles were less abundant in the cloud residues. In the case of amines this can be explained by the high solubility of the amines, while the large soot-containing particles were found to be internally mixed with inorganics, which explains their activation as cloud condensation nuclei. Furthermore, the results show that during cloud processing, both sulphate and nitrate are added to the residual particles, thereby changing the mixing state and increasing the fraction of particles with nitrate and/or sulphate. This is expected to lead to higher hygroscopicity after cloud evaporation, and therefore to an increase of the particles

  8. Aerosol properties, source identification, and cloud processing in orographic clouds measured by single particle mass spectrometry on a central European mountain site during HCCT-2010

    NASA Astrophysics Data System (ADS)

    Roth, A.; Schneider, J.; Klimach, T.; Mertes, S.; van Pinxteren, D.; Herrmann, H.; Borrmann, S.

    2016-01-01

    Cloud residues and out-of-cloud aerosol particles with diameters between 150 and 900 nm were analysed by online single particle aerosol mass spectrometry during the 6-week study Hill Cap Cloud Thuringia (HCCT)-2010 in September-October 2010. The measurement location was the mountain Schmücke (937 m a.s.l.) in central Germany. More than 160 000 bipolar mass spectra from out-of-cloud aerosol particles and more than 13 000 bipolar mass spectra from cloud residual particles were obtained and were classified using a fuzzy c-means clustering algorithm. Analysis of the uncertainty of the sorting algorithm was conducted on a subset of the data by comparing the clustering output with particle-by-particle inspection and classification by the operator. This analysis yielded a false classification probability between 13 and 48 %. Additionally, particle types were identified by specific marker ions. The results from the ambient aerosol analysis show that 63 % of the analysed particles belong to clusters having a diurnal variation, suggesting that local or regional sources dominate the aerosol, especially for particles containing soot and biomass burning particles. In the cloud residues, the relative percentage of large soot-containing particles and particles containing amines was found to be increased compared to the out-of-cloud aerosol, while, in general, organic particles were less abundant in the cloud residues. In the case of amines, this can be explained by the high solubility of the amines, while the large soot-containing particles were found to be internally mixed with inorganics, which explains their activation as cloud condensation nuclei. Furthermore, the results show that during cloud processing, both sulfate and nitrate are added to the residual particles, thereby changing the mixing state and increasing the fraction of particles with nitrate and/or sulfate. This is expected to lead to higher hygroscopicity after cloud evaporation, and therefore to an increase of

  9. Apparatus for rapid measurement of aerosol bulk chemical composition

    DOEpatents

    Lee, Yin-Nan E.; Weber, Rodney J.

    2003-01-01

    An apparatus and method for continuous on-line measurement of chemical composition of aerosol particles with a fast time resolution are provided. The apparatus includes a modified particle size magnifier for producing activated aerosol particles and a collection device which collects the activated aerosol particles into a liquid stream for quantitative analysis by analytical methods. The method provided for on-line measurement of chemical composition of aerosol particles includes exposing aerosol carrying sample air to hot saturated steam thereby forming activated aerosol particles; collecting the activated aerosol particles by a collection device for delivery as a jet stream onto an impaction surface; flushing off the activated aerosol particles from the impaction surface into a liquid stream for delivery of the collected liquid stream to an analytical instrument for quantitative measurement.

  10. Apparatus for rapid measurement of aerosol bulk chemical composition

    DOEpatents

    Lee, Yin-Nan E.; Weber, Rodney J.; Orsini, Douglas

    2006-04-18

    An apparatus for continuous on-line measurement of chemical composition of aerosol particles with a fast time resolution is provided. The apparatus includes an enhanced particle size magnifier for producing activated aerosol particles and an enhanced collection device which collects the activated aerosol particles into a liquid stream for quantitative analysis by analytical means. Methods for on-line measurement of chemical composition of aerosol particles are also provided, the method including exposing aerosol carrying sample air to hot saturated steam thereby forming activated aerosol particles; collecting the activated aerosol particles by a collection device for delivery as a jet stream onto an impaction surface; and flushing off the activated aerosol particles from the impaction surface into a liquid stream for delivery of the collected liquid stream to an analytical instrument for quantitative measurement.

  11. The hygroscopicity of indoor aerosol particles

    SciTech Connect

    Wei, L.

    1993-07-01

    A system to study the hygroscopic growth of particle was developed by combining a Tandem Differential Mobility Analyzer (TDMA) with a wetted wall reactor. This system is capable of mimicking the conditions in human respiratory tract, and measuring the particle size change due to the hygroscopic growth. The performance of the system was tested with three kinds of particles of known composition, NaCl, (NH{sub 4}){sub 2}SO{sub 4}, and (NH{sub 4})HS0{sub 4} particles. The hygroscopicity of a variety of common indoor aerosol particles was studied including combustion aerosols (cigarette smoking, cooking, incenses and candles) and consumer spray products such as glass cleaner, general purpose cleaner, hair spray, furniture polish spray, disinfectant, and insect killer. Experiments indicate that most of the indoor aerosols show some hygroscopic growth and only a few materials do not. The magnitude of hygroscopic growth ranges from 20% to 300% depending on the particle size and fraction of water soluble components.

  12. 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.

  13. Sources and transformations of atmospheric aerosol particles

    NASA Astrophysics Data System (ADS)

    Cross, Eben Spencer

    Aerosol particles are an important component of the Earth-Atmosphere system because of their influence on the radiation budget both directly (through absorption and scattering) and indirectly (through cloud condensation nuclei (CCN) activity). The magnitude of the raditaive forcing attributed to the direct and indirect aerosol effects is highly uncertain, leading to large uncertainties in projections of global climate change. Real-time measurements of aerosol properties are a critical step toward constraining the uncertainties in current global climate modeling and understanding the influence that anthropogenic activities have on the climate. The objective of the work presented in this thesis is to gain a more complete understanding of the atmospheric transformations of aerosol particles and how such transformations influence the direct and indirect radiative effects of the particles. The work focuses on real-time measurements of aerosol particles made with the Aerodyne Aerosol Mass Spectrometer (AMS) developed in collaboration with the Boston College research group. A key feature of the work described is the development of a light scattering module for the AMS. Here we present the first results obtained with the integrated light scattering - AMS system. The unique and powerful capabilities of this new instrument combination are demonstrated through laboratory experiments and field deployments. Results from two field studies are presented: (1) The Northeast Air Quality Study (NEAQS), in the summer of 2004, conducted at Chebogue Point, Nova Scotia and (2) The Megacity Initiative: Local and Global Research Observations (MILAGRO) field campaign conducted in and around Mexico City, Mexico in March of 2006. Both field studies were designed to study the transformations that occur within pollution plumes as they are transported throughout the atmosphere. During the NEAQS campaign, the pollution plume from the Northeastern United States was intercepted as it was

  14. Fluorescent biological aerosol particles measured with the Waveband Integrated Bioaerosol Sensor WIBS-4: laboratory tests combined with a one year field study

    NASA Astrophysics Data System (ADS)

    Toprak, E.; Schnaiter, M.

    2013-01-01

    In this paper bioaerosol measurements conducted with the Waveband Integrated Bioaerosol Sensor mark 4 (WIBS-4) are presented. The measurements comprise aerosol chamber characterization experiments and a one-year ambient measurement period at a semi-rural site in South Western Germany. This study aims to investigate the sensitivity of WIBS-4 to biological and non-biological aerosols and detection of biological particles in the ambient aerosol. Several types of biological and non-biological aerosol samples, including fungal spores, bacteria, mineral dust, ammonium sulphate, combustion soot, and fluorescent polystyrene spheres, were analyzed by WIBS-4 in the laboratory. The results confirm the sensitivity of the ultraviolet light-induced fluorescence (UV-LIF) method to biological fluorophores and show the good discrimination capabilities of the two excitation wavelengths/detection wavebands method applied in WIBS-4. However, a weak cross-sensitivity to non-biological fluorescent interferers remains and is discussed in this paper. All the laboratory studies have been undertaken in order to prepare WIBS-4 for ambient aerosol measurements. According to the one-year ambient aerosol study, number concentration of fluorescent biological aerosol particles (FBAP) show strong seasonal and diurnal variability. The highest number concentration of FBAP was measured during the summer term and decreased towards the winter period when colder and drier conditions prevail. Diurnal FBAP concentrations start to increase after sunset and reach maximum values during the late night and early morning hours. On the other hand, the total aerosol number concentration was almost always higher during daytime than during nighttime and a sharp decrease after sunset was observed. There was no correlation observed between the FBAP concentration and the meteorological parameters temperature, precipitation, wind direction and wind speed. However, a clear correlation was identified between the FBAP

  15. 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.

  16. Vertical profiles of fine and coarse aerosol particles over Cyprus: Comparison between in-situ drone measurements and remote sensing observations

    NASA Astrophysics Data System (ADS)

    Mamali, Dimitra; Marinou, Eleni; Pikridas, Michael; Kottas, Michael; Binietoglou, Ioannis; Kokkalis, Panagiotis; Tsekeri, Aleksandra; Amiridis, Vasilis; Sciare, Jean; Keleshis, Christos; Engelmann, Ronny; Ansmann, Albert; Russchenberg, Herman W. J.; Biskos, George

    2017-04-01

    Vertical profiles of the aerosol mass concentration derived from light detection and ranging (lidar) measurements were compared to airborne dried optical particle counter (OPC MetOne; Model 212) measurements during the INUIT-BACCHUS-ACTRIS campaign. The campaign took place in April 2016 and its main focus was the study of aerosol dust particles. During the campaign the NOA Polly-XT Raman lidar located at Nicosia (35.08° N, 33.22° E) was providing round-the-clock vertical profiles of aerosol optical properties. In addition, an unmanned aerial vehicle (UAV) carrying an OPC flew on 7 days during the first morning hours. The flights were performed at Orounda (35.1018° N, 33.0944° E) reaching altitudes of 2.5 km a.s.l, which allows comparison with a good fraction of the recorded lidar data. The polarization lidar photometer networking method (POLIPHON) was used for the estimation of the fine (non-dust) and coarse (dust) mode aerosol mass concentration profiles. This method uses as input the particle backscatter coefficient and the particle depolarization profiles of the lidar at 532 nm wavelength and derives the aerosol mass concentration. The first step in this approach makes use of the lidar observations to separate the backscatter and extinction contributions of the weakly depolarizing non-dust aerosol components from the contributions of the strongly depolarizing dust particles, under the assumption of an externally mixed two-component aerosol. In the second step, sun photometer retrievals of the fine and the coarse modes aerosol optical thickness (AOT) and volume concentration are used to calculate the associated concentrations from the extinction coefficients retrieved from the lidar. The estimated aerosol volume concentrations were converted into mass concentration with an assumption for the bulk aerosol density, and compared with the OPC measurements. The first results show agreement within the experimental uncertainty. This project received funding from the

  17. Measuring the temporal evolution of aerosol composition in a remote marine environment influenced by Saharan dust outflow using a new single particle mass spectrometer.

    NASA Astrophysics Data System (ADS)

    Marsden, Nicholas; Williams, Paul; Flynn, Michael; Taylor, Jonathan; Liu, Dantong; Allan, James; Coe, Hugh

    2016-04-01

    Refractory material constitutes a significant fraction of the atmospheric aerosol burden and has a strong influence on climate through the direct radiative effect and aerosol-cloud interactions, particularly in cold and mixed phase clouds. Composition of refractory aerosols is traditionally measured using off-line analytical techniques such as filter analyses. However, when using off-line techniques the temporal evolution of the data set is lost, meaning the measurements are difficult to relate to atmospheric processes. Recently, single particle mass spectrometry (SPMS) has proven a useful tool for the on-line study of refractory aerosols with the ability to probe size resolved chemical composition with high temporal resolution on a particle by particle basis. A new Laser Ablation Aerosol Time-of-Flight (LAAP-TOF) SPMS instrument with a modified optical detection system was deployed for ground based measurements at Praia, Cape Verde during the Ice in Cloud - Dust (ICE-D) multi-platform campaign in August 2015. A primary aim of the project was to evaluate the impact of Saharan dust on ice nucleation in mixed phase clouds. The instrument was operated over a 16 day period in which several hundred thousand single particle mass spectra were obtained from air masses with back trajectories traversing the Mid-Atlantic, Sahara Desert and West Africa. The data presented indicate external mixtures of sea salt and silicate mineral dust internally mixed with secondary species that are consistent with long range transport to a remote marine environment. The composition and size distributions measured with the LAAP-TOF are compared with measurements from an aerodynamic particle sizer (APS), Single Particle Soot Photometer (SP2), and data from SEM-EDX analysis of filter samples. The particle number fraction identified as silicate mineral from the mass spectra correlates with a fraction of the incandescent particles measured with the SP2. We discuss the suitability of the modified

  18. Hygroscopic growth of atmospheric aerosol particles based on lidar, radiosonde, and in situ measurements: Case studies from the Xinzhou field campaign

    NASA Astrophysics Data System (ADS)

    Lv, Min; Liu, Dong; Li, Zhanqing; Mao, Jietai; Sun, Yele; Wang, Zhenzhu; Wang, Yingjian; Xie, Chenbo

    2017-02-01

    Lidar, radiosonde, and ground-based in situ nephelometer measurements made during an intensive field campaign carried out from July to September 2014 at the Xinzhou meteorological station were used to determine the aerosol hygroscopic growth effect in a cloud-capped, well-mixed boundary layer. Aerosol hygroscopic properties at 355 and 532 nm were examined for two cases with distinct aerosol layers. Lidar-derived maximum enhancement factors in terms of aerosol backscatter coefficient derived using a relative humidity (RH) reference value of 85% were 1.19 at 532 nm and 1.10 at 355 nm for Case I and 2.32 at 532 nm and 1.94 at 355 nm for Case II. To derive the aerosol particle hygroscopic growth factor at specific RH values, the Kasten and Hänel models were used. A comparison of the goodness of fit for the two models showed that the Kasten model performed better. The hygroscopic growth curve for RH>90% was much steeper than that for RH in the range of 85-90%. The slopes of the lidar-derived enhancement factor curve (measured from 85% to 95% RH) and the nephelometer-derived enhancement factor curve (measured from 40% to 62% RH) in Case I show similar trends, which lends confidence to using lidar measurements for studying aerosol particle hygroscopic growth. Data from a ground aerosol chemical speciation monitor showed that the larger values of aerosol hygroscopic enhancement factor in Case II corresponded to greater mass concentrations of sulfate and nitrate in the atmosphere.

  19. 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.

  20. Fatty Acids as Surfactants on Aerosol Particles

    NASA Astrophysics Data System (ADS)

    Tervahattu, H.; Juhanoja, J.; Niemi, J.

    2003-12-01

    Fatty acids (n-alcanoic acids) are common compounds in numerous anthropogenic and natural emissions. According to Rogge et al. (1993), catalyst-equipped automobiles emitted more than 600 μg km-1 of fatty acids which was over 50% of all identified organics in fine aerosol emissions. Coal burning produces fatty acids ranging from about 1700 mg kg-1 for bituminous coal to over 10000 mg kg-1 for lignite (Oros and Simoneit, 2000). Similarly, biomass burning is an important source for aerosol fatty acids. They are the major identified compound group in deciduous tree smoke, their total emission factor being measured as 1589 mg kg-1 which was 56% of all identified organic compounds (Oros and Simoneit, 2001a). Large amounts of fatty acid are also emitted from burning of conifer trees and grass (Oros and Simoneit, 2001a; Simoneit, 2002). Fatty acids have been reported to be major constituents of marine aerosols in many investigations (Barger and Garrett, 1976; Gagosian et. al, 1981; Sicre et al., 1990; Stephanou, 1992). It has been suggested that as the marine aerosol particles form, they acquire a coating of organic surfactants (Blanchard, 1964; Gill et al., 1983; Middlebrook et al., 1998; Ellison et al., 1999). Amphiphilic molecules, including lipids, can be assembled as monomolecular layers at air/water interfaces as well as transported to a solid support. Recently, we could show by time-of-flight secondary ion mass spectrometry that fatty acids are important ingredients of the outermost surface layer of the sea-salt aerosol particles (Tervahattu et al., 2002). In their TOF-SIMS studies on the surface composition of atmospheric aerosols, Peterson and Tyler (2002) found fatty acids on the surface of Montana forest fire particles. In this work we have studied by TOF-SIMS the surface chemical composition of aerosol particles emitted from field fires in the Baltic and other East European countries and transported to Finland as well as aerosol particles transported from

  1. Factors affecting non-tailpipe aerosol particle emissions from paved roads: On-road measurements in Stockholm, Sweden

    NASA Astrophysics Data System (ADS)

    Hussein, Tareq; Johansson, Christer; Karlsson, Hans; Hansson, Hans-Christen

    A large fraction of urban PM 10 concentrations is due to non-exhaust traffic emissions. In this paper, a mobile measurement system has been used to quantify the relative importance of road particle emission and suspension of accumulated dust versus direct pavement wear, tire type (studded, friction, and summer), pavement type, and vehicle speed. Measurements were performed during May-September on selected roads with different pavements and traffic conditions in the Stockholm region. The highest particle mass concentrations were always observed behind the studded tire and the lowest were behind the summer tire; studded-to-summer ratios were 4.4-17.3 and studded-to-friction ratios were 2.0-6.4. This indicates that studded tires lead to higher emissions than friction and summer tires regardless to the asphalt type. By comparing with measurements in a road simulator, it could be estimated that the pavement wear due to the friction tires was 0.018-0.068 of the suspension of accumulated road dust. Likewise for studded tires road-wear was estimated to be 1.2-4.8 the suspension of accumulated dust. This indicates that wear due to friction tires is very small compared to the suspension of accumulated dust and that suspension due to studded tires may sometimes be as large as the wear of the road. But this will vary depending on, e.g. the amount of dust accumulated on the roads. An important dependence on vehicle speed was also observed. During May, the particle mass concentrations behind the studded tire at vehicle speed 100 km h -1 were about 10 times higher than that at 20 km h -1. The speed dependence was not so pronounced in September, which could be due to less accumulated dust on the roads. The particle number size distribution of the emissions due to road wear by studded tire was characterized by a clear increase in number concentrations of the coarse fraction of aerosol particles, with a geometric mean diameter between 3 and 5 μm. The size distribution of the

  2. 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.

  3. Optical Trapping-Cavity Ringdown Spectroscopy System for Single Aerosol Particle Measurements

    DTIC Science & Technology

    2015-02-17

    focused 532 nm laser ( Bermuda grass smut spores, horizontal illumination at power of 4.5 mW, focus length = 10 mm, UV quartz cuvette is from Starna...Cells, Inc.) (b) Single bioaerosol particles trapped using a focused 405 nm laser ( Bermuda grass smut spores, upward illumination at power of 2.0

  4. A review of atmospheric aerosol measurements

    NASA Astrophysics Data System (ADS)

    McMurry, Peter H.

    Recent developments in atmospheric aerosol measurements are reviewed. The topics included complement those covered in the recent review by Chow (JAWMA 45: 320-382, 1995) which focuses on regulatory compliance measurements and filter measurements of particulate composition. This review focuses on measurements of aerosol integral properties (total number concentration, CCN concentration, optical coefficients, etc.), aerosol physical chemical properties (density, refractive index, equilibrium water content, etc.), measurements of aerosol size distributions, and measurements of size-resolved aerosol composition. Such measurements play an essential role in studies of secondary aerosol formation by atmospheric chemical transformations and enable one to quantify the contributions of various species to effects including light scattering/absorption, health effects, dry deposition, etc. Aerosol measurement evolved from an art to a science in the 1970s following the development of instrumentation to generate monodisperse calibration aerosols of known size, composition, and concentration. While such calibration tools permit precise assessments of instrument responses to known laboratory-generated aerosols, unquantifiable uncertainties remain even when carefully calibrated instruments are used for atmospheric measurements. This is because instrument responses typically depend on aerosol properties including composition, shape, density, etc., which, for atmospheric aerosols, may vary from particle-to-particle and are often unknown. More effort needs to be made to quantify measurement accuracies that can be achieved for realistic atmospheric sampling scenarios. The measurement of organic species in atmospheric particles requires substantial development. Atmospheric aerosols typically include hundreds of organic compounds, and only a small fraction (˜10%) of these can be identified by state-of-the-art analytical methodologies. Even the measurement of the total particulate organic

  5. 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.

  6. Optical properties of urban aerosols, aircraft emissions, and heavy-duty diesel trucks using aerosol light extinction measurements by an Aerodyne Cavity Attenuated Phase Shift Particle Extinction Monitor (CAPS PMex)

    NASA Astrophysics Data System (ADS)

    Freedman, A.; Massoli, P.; Wood, E. C.; Allan, J. D.; Fortner, E.; Yu, Z.; Herndon, S. C.; Miake-Lye, R. C.; Onasch, T. B.

    2010-12-01

    We present results of optical property characterization of ambient particulate during several field deployments where measurements of aerosol light extinction (σep) are obtained using an Aerodyne Cavity Attenuated Phase Shift Particle Extinction Monitor (CAPS PMex). The CAPS PMex is able to provide extinction measurements with 3-σ detection limit of 3 Mm-1 for 1s integration time. The CAPS PMex (630 nm) is integrated in the Aerodyne Research, Inc. (ARI) mobile laboratory where a co-located Multi Angle Absorption Photometer (MAAP) provides particle light absorption coefficient at 632 nm. The combination of the CAPS with the MAAP data allows estimating the single scattering albedo (ω) of the ambient aerosol particles. The ARI mobile laboratory was deployed in winter 2010 at the Chicago O’Hare International Airport to measure gas phase and particulate emissions from different aircraft engines, and during summer 2010 in Oakland, CA, to characterize vehicular gaseous and particulate emissions (mainly exhaust from heavy-duty diesel trucks) from the Caldecott Tunnel. We provide estimates of black carbon emission factors from individual aircraft engines and diesel trucks, in addition to characterizing the optical properties of these ambient samples studying fleet-average emissions for both light-duty passenger vehicles and heavy-duty diesel trucks. Two CAPS PMex instruments (measuring σep at 630 and 532 nm) were also deployed during the CalNex 2010 study (May 14 - June 16) at the CalTech ground site in Pasadena, CA. During the same time, a photo-acoustic spectrometer (PAS, DMT) and an aethalometer instrument (Magee Sci.) measured particle light absorption of submicron aerosol particles from the same sample line as the CAPS PMex monitors. We combine these data to provide multi-wavelength ω trends for the one-month campaign. Our results show the high potential of the CAPS as light weight, compact instrument to perform precise and accurate σep measurements of

  7. 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

  8. 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

  9. Particle size distributions of several commonly used seeding aerosols

    NASA Technical Reports Server (NTRS)

    Crosswy, F. L.

    1985-01-01

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

  10. Fluorescent biological aerosol particles (FBAPs) measured with the Waveband Integrated Bioaerosol Sensor WIBS-4: laboratory tests combined with a one year field study

    NASA Astrophysics Data System (ADS)

    Toprak, E.; Schnaiter, M.

    2012-07-01

    In this paper bioaerosol measurements conducted with the Waveband Integrated Bioaerosol Sensor mark 4 (WIBS-4) are presented. The measurements comprise aerosol chamber characterization experiments and a one-year ambient measurement period at a semi-rural site in South Western Germany. This study aims to investigate the sensitivity of WIBS-4 to biological and non-biological aerosols, performance of WIBS-4 for discrimination of several types of aerosols, and the detection and identification of biological particles in the ambient aerosol. Several types of biological and non-biological aerosol samples including spores, bacteria, pollen, mineral dust, ammonium sulphate, combustion soot, and fluorescent polystyrene spheres were analysed by WIBS-4 in the laboratory. The results confirm the sensitivity of the Ultra Violet Light Induced Fluorescence (UV-LIF) method to biological fluorophores and show the good discrimination capabilities of the two wavelengths excitation/two wavebands detection method applied in WIBS-4. However, a weak cross-sensitivity to non-biological fluorescent interferers remains and is discussed in this paper. All the laboratory studies have been undertaken in order to prepare WIBS-4 for ambient aerosol measurements. According to the one year ambient aerosol study, number concentration of fluorescent biological aerosol particles (FBAP) show strong seasonal and diurnal variability. The highest number concentration of FBAP was measured during the summer term and it decreases towards the winter period when colder and drier conditions are prevailing. Diurnal FBAP concentrations start to increase after sunset and reach maximum values during the late night and early morning hours. On the other hand the total aerosol number concentration was always higher during day time than during night time and a sharp decrease after sunset was observed. There was no correlation observed between the FBAP concentration and the meteorological parameters temperature

  11. Characterization of Ribavirin Aerosol With Small Particle Aerosol Generator and Vibrating Mesh Micropump Aerosol Technologies.

    PubMed

    Walsh, Brian K; Betit, Peter; Fink, James B; Pereira, Luis M; Arnold, John

    2016-05-01

    Ribavirin is an antiviral drug that can be administered by inhalation. Despite advancements in the oral delivery of this medication, there has been a renewed interested in delivering ribavirin via the pulmonary system. Although data are not conclusive that inhaled ribavirin improves outcomes, we set out to determine whether delivery by a newer generation nebulizer, the vibrating mesh micropump, was as effective as the recommended small-particle aerosol generator system. We compared the physicochemical makeup and concentrations of ribavirin before and after nebulization with 0.9% NaCl and sterile water. An Andersen cascade impactor was used to determine particle size distribution and mass median aerodynamic diameter, and an absolute filter was used to measure total aerosol emitted output and inhaled dose during mechanical ventilation and spontaneous breathing. Ribavirin was analyzed and quantified using high-performance liquid chromatography with tandem mass spectrometric detection. Ribavirin was found to be stable in both 0.9% aqueous NaCl and sterile water with an r(2) value of 0.96 and identical coefficients of variation with no difference in drug concentration before and after nebulization with the vibrating mesh micropump. The small-particle aerosol generator produced a smaller mass median aerodynamic diameter (1.84 μm) than the vibrating mesh micropump (3.63 μm, P = .02); however, there was no significant difference in the proportion of drug mass in the 0.7-4.7-μm particle range. Total drug delivery was similar with the small-particle aerosol generator and vibrating mesh micropump in both spontaneously breathing (P = .77) and mechanical ventilation (P = .48) models. The vibrating mesh micropump nebulizer may provide an effective alternative to the small-particle aerosol generator in administration of ribavirin using NaCl or sterile water, both on and off the ventilator. Further clinical studies are needed to compare efficacy. Copyright © 2016 by Daedalus

  12. 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.

  13. Rapid Measurements of Aerosol Ionic Composition and 3-10 nm Particle Size Distributions On The NASA P3 To Better Quantify Processes Affecting Aerosols Advected From East Asia

    NASA Technical Reports Server (NTRS)

    Weber, Rodney J.

    2004-01-01

    The Particle Into Liquid Sample (PILS) was deployed on the NASA P3 for airborne measurements of fine particle ionic chemical composition. The data have been quality assured and reside in the NASA data archive. We have analyzed our data to characterize the sources and atmospheric processing of fine aerosol particles advected from the region during the experiments. Fine particle water-soluble potassium was found to serve as a useful aerosol tracer for biomass smoke. Ratios of PILS potassium to sulfate are used as a means of estimating the percent contribution of biomass burning to fine particle mass in mixed plumes advecting from Asia. The high correlations between K+ and NO3(sup -) and NH4(sup +)' indicated that biomass burning was a significant source of these aerosol compounds in the region. It is noteworthy that the air mass containing the highest concentrations of fine particles recorded in all of ACE-Asia and TRACE-P appeared to be advecting from the Bejing/Tientsin urban region and also had the highest K(+), NO3(sup -) and NH4(sup +) concentrations of both studies. Based on K+/SO4(sup 2-) ratio's, we estimated that the plume was composed of approx. 60% biomass burning emissions, possibly from the use of bio-fuels in the urban regions.

  14. Rapid Measurements of Aerosol Ionic Composition and 3-10 nm Particle Size Distributions On The NASA P3 To Better Quantify Processes Affecting Aerosols Advected From East Asia

    NASA Technical Reports Server (NTRS)

    Weber, Rodney J.

    2004-01-01

    The Particle Into Liquid Sample (PILS) was deployed on the NASA P3 for airborne measurements of fine particle ionic chemical composition. The data have been quality assured and reside in the NASA data archive. We have analyzed our data to characterize the sources and atmospheric processing of fine aerosol particles advected from the region during the experiments. Fine particle water-soluble potassium was found to serve as a useful aerosol tracer for biomass smoke. Ratios of PILS potassium to sulfate are used as a means of estimating the percent contribution of biomass burning to fine particle mass in mixed plumes advecting from Asia. The high correlations between K+ and NO3(sup -) and NH4(sup +)' indicated that biomass burning was a significant source of these aerosol compounds in the region. It is noteworthy that the air mass containing the highest concentrations of fine particles recorded in all of ACE-Asia and TRACE-P appeared to be advecting from the Bejing/Tientsin urban region and also had the highest K(+), NO3(sup -) and NH4(sup +) concentrations of both studies. Based on K+/SO4(sup 2-) ratio's, we estimated that the plume was composed of approx. 60% biomass burning emissions, possibly from the use of bio-fuels in the urban regions.

  15. Atmospheric aerosol measurements from satellites

    NASA Astrophysics Data System (ADS)

    Borodai, Nataliia

    Satellite instruments are commonly used for measurements of aerosol optical properties in the atmosphere. In this work we use such measurements for ultra-high energy cosmic ray studies. We introduce a method of preparation of aerosol maps for the location of the Pierre Auger Observatory. For these maps the data from the Ozone Monitoring Instrument (OMI) of the Aura satellite were analyzed for the period 2004-2016. Such aerosol properties as the aerosol optical depth (AOD) and aerosol types were retrieved. The seasonal dependence of aerosol distribution is also studied.

  16. LOAC: a small aerosol optical counter/sizer for ground-based and balloon measurements of the size distribution and nature of atmospheric particles - Part 1: Principle of measurements and instrument evaluation

    NASA Astrophysics Data System (ADS)

    Renard, Jean-Baptiste; Dulac, François; Berthet, Gwenaël; Lurton, Thibaut; Vignelles, Damien; Jégou, Fabrice; Tonnelier, Thierry; Jeannot, Matthieu; Couté, Benoit; Akiki, Rony; Verdier, Nicolas; Mallet, Marc; Gensdarmes, François; Charpentier, Patrick; Mesmin, Samuel; Duverger, Vincent; Dupont, Jean-Charles; Elias, Thierry; Crenn, Vincent; Sciare, Jean; Zieger, Paul; Salter, Matthew; Roberts, Tjarda; Giacomoni, Jérôme; Gobbi, Matthieu; Hamonou, Eric; Olafsson, Haraldur; Dagsson-Waldhauserova, Pavla; Camy-Peyret, Claude; Mazel, Christophe; Décamps, Thierry; Piringer, Martin; Surcin, Jérémy; Daugeron, Daniel

    2016-04-01

    The study of aerosols in the troposphere and in the stratosphere is of major importance both for climate and air quality studies. Among the numerous instruments available, optical aerosol particles counters (OPCs) provide the size distribution in diameter range from about 100 nm to a few tens of µm. Most of them are very sensitive to the nature of aerosols, and this can result in significant biases in the retrieved size distribution. We describe here a new versatile optical particle/sizer counter named LOAC (Light Optical Aerosol Counter), which is light and compact enough to perform measurements not only at the surface but under all kinds of balloons in the troposphere and in the stratosphere. LOAC is an original OPC performing observations at two scattering angles. The first one is around 12°, and is almost insensitive to the refractive index of the particles; the second one is around 60° and is strongly sensitive to the refractive index of the particles. By combining measurement at the two angles, it is possible to retrieve the size distribution between 0.2 and 100 µm and to estimate the nature of the dominant particles (droplets, carbonaceous, salts and mineral particles) when the aerosol is relatively homogeneous. This typology is based on calibration charts obtained in the laboratory. The uncertainty for total concentrations measurements is ±20 % when concentrations are higher than 1 particle cm-3 (for a 10 min integration time). For lower concentrations, the uncertainty is up to about ±60 % for concentrations smaller than 10-2 particle cm-3. Also, the uncertainties in size calibration are ±0.025 µm for particles smaller than 0.6 µm, 5 % for particles in the 0.7-2 µm range, and 10 % for particles greater than 2 µm. The measurement accuracy of submicronic particles could be reduced in a strongly turbid case when concentration of particles > 3 µm exceeds a few particles cm-3. Several campaigns of cross-comparison of LOAC with other particle counting

  17. Aerosol measurement program strategy for global aerosol backscatter model development

    NASA Technical Reports Server (NTRS)

    Bowdle, David A.

    1985-01-01

    The purpose was to propose a balanced program of aerosol backscatter research leading to the development of a global model of aerosol backscatter. Such a model is needed for feasibility studies and systems simulation studies for NASA's prospective satellite-based Doppler lidar wind measurement system. Systems of this kind measure the Doppler shift in the backscatter return from small atmospheric aerosol wind tracers (of order 1 micrometer diameter). The accuracy of the derived local wind estimates and the degree of global wind coverage for such a system are limited by the local availability and by the global scale distribution of natural aerosol particles. The discussions here refer primarily to backscatter model requirements at CO2 wavelengths, which have been selected for most of the Doppler lidar systems studies to date. Model requirements for other potential wavelengths would be similar.

  18. Aerosol measurement program strategy for global aerosol backscatter model development

    NASA Technical Reports Server (NTRS)

    Bowdle, David A.

    1985-01-01

    The purpose was to propose a balanced program of aerosol backscatter research leading to the development of a global model of aerosol backscatter. Such a model is needed for feasibility studies and systems simulation studies for NASA's prospective satellite-based Doppler lidar wind measurement system. Systems of this kind measure the Doppler shift in the backscatter return from small atmospheric aerosol wind tracers (of order 1 micrometer diameter). The accuracy of the derived local wind estimates and the degree of global wind coverage for such a system are limited by the local availability and by the global scale distribution of natural aerosol particles. The discussions here refer primarily to backscatter model requirements at CO2 wavelengths, which have been selected for most of the Doppler lidar systems studies to date. Model requirements for other potential wavelengths would be similar.

  19. Balloon-borne measurements of aerosol, condensation nuclei, and cloud particles in the stratosphere at McMurdo Station, Antarctica, during the spring of 1987

    NASA Technical Reports Server (NTRS)

    Hofmann, D. J.; Rosen, J. M.; Harder, J. W.; Hereford, J. V.

    1989-01-01

    Measurements of the vertical profile of particles with condensation nuclei counters and eight channel aerosol detectors at McMurdo Station, Antarctica, in 1987 verified observations made in 1986 concerning the absence of upwelling in the polar vortex and the presence of a condensation nuclei layer in conjunction with the ozone hole region. New observations of a bimodal aerosol size distribution, consisting of a large-particle mode mixed in with the small-particle sulfate mode, at temperatures below -79 C are consistent with the presence of nitric acid-water particles at low concentrations. Higher concentrations of large particles were observed in association with nacreous clouds. An unusual particle layer which contained enhanced concentrations of both the small-particle (sulfate) mode and the large-particle (nitric acid) mode was detected at temperatures below -85 C, suggesting simultaneous nucleation and growth phenomena. The vortex condensation nuclei layer was observed to form at the same time as the ozone hole, indicating that formation of the layer is triggered by photochemical processes and may be important in controlling ozone depletion above 22 km.

  20. Measuring Sodium Chloride Contents of Aerosols

    NASA Technical Reports Server (NTRS)

    Sinha, M. P.; Friedlander, S. K.

    1986-01-01

    Amount of sodium chloride in individual aerosol particles measured in real time by analyzer that includes mass spectrometer. Analyzer used to determine mass distributions of active agents in therapeutic or diagnostic aerosols derived from saline solutions and in analyzing ocean spray. Aerosol particles composed of sodium chloride introduced into oven, where individually vaporized on hot wall. Vapor molecules thermally dissociated, and some of resulting sodium atoms ionized on wall. Ions leave oven in burst and analyzed by spectrometer, which is set to monitor sodium-ion intensity.

  1. Sources of optically active aerosol particles over the Amazon forest

    NASA Astrophysics Data System (ADS)

    Guyon, Pascal; Graham, Bim; Roberts, Gregory C.; Mayol-Bracero, Olga L.; Maenhaut, Willy; Artaxo, Paulo; Andreae, Meinrat O.

    Size-fractionated ambient aerosol samples were collected at a pasture site and a primary rainforest site in the Brazilian Amazon Basin during two field campaigns (April-May and September-October 1999), as part of the European contribution to the Large-Scale Biosphere-Atmosphere Experiment in Amazonia (LBA-EUSTACH). The samples were analyzed for up to 19 trace elements by particle-induced X-ray emission analysis (PIXE), for equivalent black carbon (BC e) by a light reflectance technique and for mass concentration by gravimetric analysis. Additionally, we made continuous measurements of absorption and light scattering by aerosol particles. The vertical chemical composition gradients at the forest site have been discussed in a companion article (Journal of Geophysical Research-Atmospheres 108 (D18), 4591 (doi:4510.1029/2003JD003465)). In this article, we present the results of a source identification and quantitative apportionment study of the wet and dry season aerosols, including an apportionment of the measured scattering and absorption properties of the total aerosol in terms of the identified aerosol sources. Source apportionments (obtained from absolute principal component analysis) revealed that the wet and dry season aerosols contained the same three main components, but in different (absolute and relative) amounts: the wet season aerosol consisted mainly of a natural biogenic component, whereas pyrogenic aerosols dominated the dry season aerosol mass. The third component identified was soil dust, which was often internally mixed with the biomass-burning aerosol. All three components contributed significantly to light extinction during both seasons. At the pasture site, up to 47% of the light absorption was attributed to biogenic particles during the wet season, and up to 35% at the tower site during the wet-to-dry transition period. The results from the present study suggest that, in addition to pyrogenic particles, biogenic and soil dust aerosols must be

  2. Glassy aerosols heterogeneously nucleate cirrus ice particles

    NASA Astrophysics Data System (ADS)

    Wilson, Theodore W.; Murray, Benjamin J.; Dobbie, Steven; Cui, Zhiqiang; Al-Jumur, Sardar M. R. K.; Möhler, Ottmar; Schnaiter, Martin; Wagner, Robert; Benz, Stefan; Niemand, Monika; Saathoff, Harald; Ebert, Volker; Wagner, Steven; Kärcher, Bernd

    2010-05-01

    Ice clouds in the tropical tropopause layer (TTL, ~12-18 km, ~180-200 K) play a key role in dehydrating air entering the stratosphere. However, in-situ measurements show that air within these clouds is unexpectedly supersaturated(1); normally the growth of ice crystals rapidly quenches any supersaturation. A number of explanations for high in-cloud humidity have been put forward, but recent research suggests high humidity may be related to the low numbers of ice crystals found within these clouds(1). Low ice number densities can be produced through selective nucleation by a small subset of aerosol particles. This is inconsistent with homogeneous nucleation of ice in liquid aerosols. However, droplets rich in organic material, ubiquitous in the TTL, are known to become glassy (amorphous, non-crystalline solid) under TTL conditions(2,3). Here we show, using a large cloud simulation chamber, that glassy solution droplets nucleate ice heterogeneously at low supersaturations. Using a one-dimensional cirrus model we also show that nucleation by glassy aerosol in the TTL may explain low TTL ice number densities and high in-cloud humidity. Recent measurements of the composition of TTL cirrus residues are consistent with our findings(4). (1) Krämer, M. et al. Ice supersaturations and cirrus cloud crystal numbers. Atm. Chem. Phys. 9, 3505-3522 (2009). (2) Murray, B. J. Inhibition of ice crystallisation in highly viscous aqueous organic acid droplets. Atm. Chem. Phys. 8, 5423-5433 (2008). (3) Zobrist, B., Marcolli, C., Pedernera, D. A. & Koop, T. Do atmospheric aerosols form glasses? Atm. Chem. Phys. 8, 5221-5244 (2008). (4) Froyd, K. D., Murphy, D. M., Lawson, P., Baumgardner, D. & Herman, R. L. Aerosols that form subvisible cirrus at the tropical tropopause. Atmos. Chem. Phys. 10, 209-218 (2010).

  3. The optical manipulation and characterisation of aerosol particles

    NASA Astrophysics Data System (ADS)

    Reid, Jonathan P.

    2008-08-01

    Aerosols play a crucial role in many areas of science, ranging from atmospheric chemistry and physics, to pharmaceutical aerosols and drug delivery to the lungs, to combustion science and spray drying. The development of new methods for characterising the properties and dynamics of aerosol particles is of crucial importance if the complex role that particles play is to be more fully understood. Optical tweezers provide a valuable new tool to address fundamental questions in aerosol science. Single or multiple particles 1-15 μm in diameter can be manipulated for indefinite timescales. Linear and non-linear Raman and fluorescence spectroscopies can be used to probe particle composition, phase, component mixing state, and size. In particular, size can be determined with nanometre accuracy, allowing accurate measurements of the thermodynamic properties of aerosols, the kinetics of particle transformation and of light absorption. Further, the simultaneous manipulation of multiple particles in parallel optical traps provides a method for performing comparative measurements on particles of different composition. We will present some latest work in which optical tweezers are used to characterise aerosol dynamics, demonstrating that optical tweezers can find application in studies of hygroscopicity, the mixing state of different chemical components, including the phase separation of immiscible phases, and the kinetics of chemical transformation.

  4. Online measurements of ambient fluorescent aerosol particles by WIBS at a polluted regional site in the North China Plain: potential impact of burning activities

    NASA Astrophysics Data System (ADS)

    Su, H.; Wang, Z.; Cheng, Y.; Xie, Z.; Kecorius, S.; McMeeking, G. R.; Yu, X.; Pöhlker, C.; Zhang, M.; Wiedensohler, A.; Kuhn, U.; Poeschl, U.; Huffman, J. A.

    2015-12-01

    Online measurements of ambient fluorescent aerosol particles by WIBS at a polluted regional site in the North China Plain: potential impact of burning activities Zhibin Wang1, Xiawei Yu1,3, Simonas Kecorius2, Zhouqing Xie3, Gavin McMeeking4, Christopher Pöhlker1, Minghui, Zhang1, Alfred Wiedensohler2, Uwe Kuhn1, Yafang Cheng1, Ulrich Pöschl1, Hang Su1,*1Multiphase Chemistry and Biogeochemistry Departments, Max Planck Institute for Chemistry, Mainz 55128, Germany2Leibniz-Institute for Tropospheric Research, Leipzig 04318, Germany3School of Earth and Space Sciences, University of Science and Technology of China, Hefei 230026, China4Droplet Measurement Technologies, Boulder 80301, USA ABSTRACTBioaerosols are the main subset of super-micron particles, and significantly influence the evolution of cloud and precipitation, as well as the public health. Currently, the detection of ambient biological materials in real-time is mainly based on the presence of fluorophores in the particles. In this study, we present the wideband integrated bioaerosol spectrometer (WIBS) measurement results to characterize the fluorescent aerosol particles (FAP) at a polluted regional site (Xianghe, 39.80 °N, 116.96 °E) in the North China Plain. We observed substantially much higher number concentration of FAP as compared with those of previous studies in clean environments. We found the good agreement between the FAP number fraction in coarse mode particles (> 1 mm) and BC mass fraction in fine particles (< 1 mm), possibly indicating a majority of the observed FAP is to a certain extent related to the anthropogenic burning activities nearby. This interference and uncertainty should be especially noticed when performing fluorescence measurements in the polluted area, where the certain non-biological compounds (such as SOA, PAH and soot) may significantly lead to a positive fluorescence measurement artifacts and an overestimation of actual fluorescent biological aerosol particles. We also

  5. Regional signatures in the organic composition of marine aerosol particles

    NASA Astrophysics Data System (ADS)

    Frossard, Amanda A.; Russell, Lynn M.; Keene, William C.; Kieber, David J.; Quinn, Patricia K.; Bates, Timothy S.

    2013-05-01

    Marine aerosol particles play an important role in the earth's radiative balance, yet the sources and composition of the organic fraction remain largely unconstrained. Recent measurements have been made in order to characterize the sources, composition, and concentration of aerosol particles in the marine boundary layer. The organic composition of submicron particles derived from multiple seawater regions have been measured using Fourier Transform Infrared (FTIR) spectroscopy. Cluster analysis of FTIR organic spectra suggest different spectral signatures based on collection location, seawater composition, and ambient conditions. Measurements including non-refractory aerosol composition from a high-resolution time of flight aerosol mass spectrometer (HR-ToF-AMS), seawater composition, and wind speed were used to interpret the cluster results, depending on the availability from each campaign. FTIR spectra of ambient particles are compared to FTIR spectra of primary marine particles generated from model ocean systems to infer the ambient particle production mechanisms and aging processes. Recent measurements used in the comparison include ambient and generated marine aerosol particles measured off the coast of California during CalNex in May and June 2010. Remote ambient marine aerosol particles were collected 100 miles off the coast of Monterey in the eastern Pacific during the EPEACE experiment in July 2011. Ambient and generated marine particles were measured in two different seawater types during WACS 2012 including colder, more productive water off the coast of the northeastern United States and warmer, oligotrophic water in the Sargasso Sea. These particles are also compared with those measured in the southeastern Pacific during VOCALS and the north Atlantic during ICEALOT.

  6. Comparison of the DiSCmini aerosol monitor to a handheld condensation particle counter and a scanning mobility particle sizer for submicrometer sodium chloride and metal aerosols

    PubMed Central

    Mills, Jessica B.; Park, Jae Hong; Peters, Thomas M.

    2016-01-01

    We evaluated the robust, lightweight DiSCmini (DM) aerosol monitor for its ability to measure the concentration and mean diameter of submicrometer aerosols. Tests were conducted with monodispersed and polydispersed aerosols composed of two particle types (sodium chloride, NaCl, and spark generated metal particles, which simulate particles found in welding fume) at three different steady-state concentration ranges (Low, <103; Medium, 103–104; and High, >104 particles/cm3). Particle number concentration, lung deposited surface area (LDSA) concentration, and mean size measured with the DM were compared to those measured with reference instruments, a scanning mobility particle sizer (SMPS) and a handheld condensation particle counter (CPC). Particle number concentrations measured with the DM were within 21% of those measured by reference instruments for polydisperse aerosols. Poorer agreement was observed for monodispersed aerosols (±35% for most tests and +130% for 300-nm NaCl). LDSA concentrations measured by the DM were 96% to 155% of those estimated with the SMPS. The geometric mean diameters measured with the DM were within 30% of those measured with the SMPS for monodispersed aerosols and within 25% for polydispersed aerosols (except for the case when the aerosol contained a substantial number of particles larger than 300 nm). The accuracy of the DM is reasonable for particles smaller than 300 nm but caution should be exercised when particles larger than 300 nm are present. PMID:23473056

  7. Laboratory Experiments and Instrument Intercomparison Studies of Carbonaceous Aerosol Particles

    SciTech Connect

    Davidovits, Paul

    2015-10-20

    ) two well-characterized source of soot particles and (b) a flow reactor for controlled OH and/or O3 oxidation of relevant gas phase species to produce well-characterized SOA particles. After formation, the aerosol particles are subjected to physical and chemical processes that simulate aerosol growth and aging. A suite of instruments in our laboratory is used to characterize the physical and chemical properties of aerosol particles before and after processing. The Time of Flight Aerosol Mass Spectrometer (ToF-AMS) together with a Scanning Mobility Particle Sizer (SMPS) measures particle mass, volume, density, composition (including black carbon content), dynamic shape factor, and fractal dimension. The–ToF-AMS was developed at ARI with Boston College participation. About 120 AMS instruments are now in service (including 5 built for DOE laboratories) performing field and laboratory studies world-wide. Other major instruments include a thermal denuder, two Differential Mobility Analyzers (DMA), a Cloud Condensation Nuclei Counter (CCN), a Thermal desorption Aerosol GC/MS (TAG) and the new Soot Particle Aerosol Mass Spectrometer (SP-AMS). Optical instrumentation required for the studies have been brought to our laboratory as part of ongoing and planned collaborative projects with colleagues from DOE, NOAA and university laboratories. Optical instruments that will be utilized include a Photoacoustic Spectrometer (PAS), a Cavity Ring Down Aerosol Extinction Spectrometer (CRD-AES), a Photo Thermal Interferometer (PTI), a new 7-wavelength Aethalometer and a Cavity Attenuated Phase Shift Extinction Monitor (CAPS). These instruments are providing aerosol absorption, extinction and scattering coefficients at a range of atmospherically relevant wavelengths. During the past two years our work has continued along the lines of our original proposal. We report on 12 completed and/or continuing projects conducted during the period 08/14 to 0814/2015. These projects are described in

  8. A field measurement based scaling approach for quantification of major ions, organic carbon, and elemental carbon using a single particle aerosol mass spectrometer

    NASA Astrophysics Data System (ADS)

    Zhou, Yang; Huang, X. H. Hilda; Griffith, Stephen M.; Li, Mei; Li, Lei; Zhou, Zhen; Wu, Cheng; Meng, Junwang; Chan, Chak K.; Louie, Peter K. K.; Yu, Jian Zhen

    2016-10-01

    Single Particle Aerosol Mass Spectrometers (SPAMS) have been increasingly deployed for aerosol studies in Asia. To date, SPAMS is most often used to provide unscaled information for both the size and chemical composition of individual particles. The instrument's lack of accuracy is primarily due to only a fraction of particles being detected after collection, and the instrumental sensitivity is un-calibrated for various chemical species in mixed ambient aerosols. During a campaign from January to April 2013 at a coastal site in Hong Kong, the particle number information and ion intensity of major PM2.5 components collected by SPAMS were scaled by comparing with collocated bulk PM2.5 measurements of hourly or higher resolution. The bulk measurements include PM2.5 mass by a SHARP 5030 Monitor, major ions by a Monitor for Aerosols & Gases in ambient Air (MARGA), and organic carbon (OC) and elemental carbon (EC) by a Sunset OCEC analyzer. During the data processing, both transmission efficiency (scaled with the Scanning Mobility Particle Sizer) and hit efficiency conversion were considered, and component ion intensities quantified as peak area (PA) and relative peak area (RPA) were analyzed to track the performance. The comparison between the scaled particle mass assuming a particle density of 1.9 g cm-3 from SPAMS and PM2.5 concentration showed good correlation (R2 = 0.81) with a slope of 0.814 ± 0.004. Regression analysis results suggest an improved scaling performance using RPA compared with PA for most of the major PM2.5 components, including sulfate, nitrate, potassium, ammonium, OC and EC. Thus, we recommend preferentially scaling these species using the RPA. For periods of high K+ concentrations (>1.5 μg m-3), under-estimation of K+ by SPAMS was observed due to exceeding the dynamic range of the acquisition board. When only applying the hit efficiency correction, data for sulfate, nitrate, ammonium, potassium and OC were in reasonably good correlation (R2 = 0

  9. Ice nucleating particle concentration during a combustion aerosol event

    NASA Astrophysics Data System (ADS)

    Adams, Mike; O'Sullivan, Daniel; Porter, Grace; Sanchez-Marroquin, Alberto; Tarn, Mark; Harrison, Alex; McQuaid, Jim; Murray, Benjamin

    2017-04-01

    The formation of ice in supercooled clouds is important for cloud radiative properties, their lifetime and the formation of precipitation. Cloud water droplets can supercool to below -33oC, but in the presence of Ice Nucleating Particles (INPs) freezing can be initiated at much higher temperatures. The concentration of atmospheric aerosols that are active as INPs depends on a number of factors, such as temperature and aerosol composition and concentration. However, our knowledge of which aerosol types serve as INPs is limited. For example, there has been much discussion over whether aerosol from combustion processes are important as INP. This is significant because combustion aerosol have increased in concentration dramatically since pre-industrial times and therefore have the potential to exert a significant anthropogenic impact on clouds and climate. In this study we made measurements of INP concentrations in Leeds over a specific combustion aerosol event in order to test if there was a correlation between INP concentrations and combustion aerosol. The combustion aerosol event was on the 5th November which is a major bonfire and firework event celebrated throughout the UK. During the event we observed a factor of five increase in aerosol and a factor of 10 increase in black carbon, but observed no significant increase in INP concentration. This implies that black carbon and combustion aerosol did not compete with the background INP during this event.

  10. The effect of local sources on particle size and chemical composition and their role in aerosol-cloud interactions at Puijo measurement station

    NASA Astrophysics Data System (ADS)

    Portin, H.; Leskinen, A.; Hao, L.; Kortelainen, A.; Miettinen, P.; Jaatinen, A.; Laaksonen, A.; Lehtinen, K. E. J.; Romakkaniemi, S.; Komppula, M.

    2014-06-01

    Interactions between aerosols and liquid water clouds were studied during autumns 2010-2011 at a semiurban measurement station on Puijo tower in Kuopio, Finland. Cloud interstitial and total aerosol size distributions, particle chemical composition and hygroscopicity and cloud droplet size distribution were measured, with a focus on comparing clean air masses with those affected by local sources. On average, the polluted air contained more particles than the clean air masses, and generally the concentrations decreased during cloud events. Cloud processing was found to take place, especially in the clean air masses, and to a lesser extent in the polluted air. Some, mostly minor, differences in the average particle chemical composition between the air masses were observed. The average size and number concentration of activating particles were quite similar for both air masses, producing average droplet populations with only minor distinctions. As a case study, a long cloud event was analyzed in detail, with a special focus on the emissions from local sources, including a paper mill and a heating plant. This revealed larger variations in particle and cloud properties than the analysis of the whole data set. Clear differences in the total (between 214 and 2200 cm-3) and accumulation mode particle concentrations (between 62 and 169 cm-3) were observed. Particle chemical composition, especially the concentrations of organics (between 0.42 and 1.28 μg m-3) and sulfate (between 0.16 and 4.43 μg m-3), varied considerably. This affected the hygroscopic growth factor: for example, for 100 nm particles the range was from 1.21 to 1.45 at 90% relative humidity. Particularly, large particles, high hygroscopicities and elevated amounts of inorganics were linked with the pollutant plumes. Moreover, the particle hygroscopicity distributions in the polluted air were clearly bimodal, indicating externally mixed aerosol. The variable conditions also had an impact on cloud droplet

  11. Ageing and hygroscopicity variation of black carbon particles in Beijing measured by a quasi-atmospheric aerosol evolution study (QUALITY) chamber

    NASA Astrophysics Data System (ADS)

    Peng, Jianfei; Hu, Min; Guo, Song; Du, Zhuofei; Shang, Dongjie; Zheng, Jing; Zheng, Jun; Zeng, Limin; Shao, Min; Wu, Yusheng; Collins, Don; Zhang, Renyi

    2017-09-01

    Measurements of ageing and hygroscopicity variation of black carbon (BC) particles in Beijing were conducted using a 1.2 m3 quasi-atmospheric aerosol evolution study (QUALITY) chamber, which consisted of a bottom flow chamber through which ambient air was pulled continuously and an upper reaction chamber where ageing of BC particles occurred. Within the reaction chamber, transmission of the solar ultraviolet irradiation was approximately 50-60 %, wall loss of primary gaseous pollutants was negligible, and BC exhibited a half-lifetime of about 3-7 h. Typically, equilibrium for the primary gases, temperature and relative humidity between the reaction chamber and ambient air was established within 1 h. Rapid growth of BC particles occurred, with an average total growth of 77 ± 33 nm and average growth rate of 26 ± 11 nm h-1. Secondary organic aerosols (SOA) accounted for more than 90 % of the coating mass. The O / C ratio of SOA was 0.5, lower than the ambient level. The hygroscopic growth factor of BC particles decreased slightly with an initial thin coating layer because of BC reconstruction, but subsequently increased to 1.06-1.08 upon further ageing. The κ (kappa) values for BC particles and coating materials were calculated as 0.035 and 0.040 at the subsaturation and supersaturation conditions, respectively, indicating low hygroscopicity of coated SOA on BC particles. Hence, our results indicate that initial photochemical ageing of BC particles leads to considerable modifications to morphology and optical properties but does not appreciably alter the particle hygroscopicity in Beijing.

  12. Cloud condensation nuclei in polluted air and biomass burning smoke: Size-resolved measurements and implications for the modeling of aerosol particle hygroscopicity and CCN activity

    NASA Astrophysics Data System (ADS)

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

    2009-04-01

    Atmospheric aerosol particles serving as cloud condensation nuclei (CCN) are key elements of the hydrological cycle and climate, but their abundance, properties and sources are highly variable and not well known. We have measured and characterized CCN in polluted air and biomass burning smoke during the PRIDE-PRD2006 campaign on 1-30 July 2006 at a rural site ~60 km northwest of the mega-city Guangzhou in southeastern China. CCN efficiency spectra (activated fraction vs. dry particle diameter; 20-300 nm) were recorded at water vapor supersaturations (S) in the range of 0.07% to 1.27%. Depending on S, the dry CCN activation diameters were in the range of 30-200 nm, corresponding to effective hygroscopicity parameters kappa in the range of 0.1-0.5. The hygroscopicity of particles in the accumulation size range was generally higher than that of particles in the nucleation and Aitken size range. The campaign average value of kappa for all aerosol particles across the investigated size range was 0.3, which equals the average value of kappa for other continental locations. During a strong local biomass burning event, the activation diameters increased by ~10% and the average value of kappa dropped to 0.2, which can be considered as characteristic for freshly emitted smoke from the burning of agricultural waste. At low S (≤0.27%), the maximum activated fraction remained generally well below one, which indicates substantial proportions of externally mixed CCN-inactive particles with much lower hygroscopicity - most likely soot particles (up to ~60% at ~250 nm). The mean CCN number concentrations (N_CCN,S) ranged from 1100 cm-3 at S=0.07% to 16 000 cm-3 at S=1.27%, representing ~7% to ~85% of the total aerosol particle number concentration. Based on the measurement data, we have tested different model approaches (power laws and kappa-Köhler model) for the approximation/prediction of N_CCN,S as a function of water vapor supersaturation, aerosol particle number

  13. Aerosol size distribution and new particle formation in western Yangtze River Delta of China: two-year measurement at the SORPES station

    NASA Astrophysics Data System (ADS)

    Qi, X. M.; Ding, A. J.; Nie, W.; Petäjä, T.; Kerminen, V.-M.; Herrmann, E.; Xie, Y. N.; Zheng, L. F.; Manninen, H.; Aalto, P.; Sun, J. N.; Xu, Z. N.; Chi, X. G.; Huang, X.; Boy, M.; Virkkula, A.; Yang, X.-Q.; Fu, C. B.; Kulmala, M.

    2015-04-01

    Aerosol particles play important roles in regional air quality and global climate change. In this study, we analyzed two-year (2011-2013) of measurements of submicron particles (6-800 nm) at a suburban site in western Yangtze River delta (YRD) of East China. The number concentrations (NCs) of particles in the nucleation, Aitken and accumulation modes were 5300 ± 5500, 8000 ± 4400, 5800 ± 3200 cm-3, respectively. Number concentrations and size distributions of submicron particles were also influenced by long-range and regional transport of air masses. The highest and lowest accumulation mode particle number concentrations were observed in air masses from YRD and coastal region, respectively. Continental air masses from inland had the highest concentrations of nucleation mode particles. New particle formation (NPF) events, apparent in 44% of the effective measurement days, occurred frequently in all the seasons except winter. Radiation and pre-existing particles were found to be the main factors influencing the occurrence of NPF events. The particle formation rate was the highest in spring (3.6 ± 2.4 cm-3 s-1), whereas the particle growth rate had the highest values in summer (12.8 ± 4.4 nm h-1). The formation rate was typically high in relatively clean air masses, whereas the growth rate tended to be high in the polluted YRD air masses. The frequency of NPF events and the growth rate showed a strong year-to-year difference. In the summer of 2013, associated with a multi-week heat wave and photochemical pollution, NPF events occurred more frequently and the growth rate was much higher than in the same period of 2012. The difference in the location and strength of sub-tropical High, which influences the air mass transport pathways and solar radiation, seems to be the driving cause for year-to-year differences. This study reported the longest continuous measurement records of submicron particles in the East China and gained a comprehensive understanding of the

  14. Evolution of newly formed aerosol particles in the continental boundary layer: A case study including OH and H2SO4 measurements

    NASA Astrophysics Data System (ADS)

    Birmili, W.; Wiedensohler, A.; Plass-Dülmer, C.; Berresheim, H.

    2000-08-01

    An event of new particle formation is presented, based on simultaneous measurements of aerosol number size distributions, relevant gaseous components including H2SO4 and OH, and meteorological parameters. Measurements were conducted at Hohenpeissenberg, a rural continental mountain site in southern Germany. The event was observed under intense solar radiation, with total particle number concentrations increasing from 6000 to 25000 cm-3 within one hour, and ultrafine particles (3-11 nm) accounting for more than 50% of total number. Observed OH and H2SO4 concentrations reached maximum levels around 107 cm-3. A lower limit of the particle nucleation rate was estimated to be 3 cm-3·s-1, consistent with present models of ternary nucleation involving the H2SO4-H2O-NH3 system. Roughly 80% of the subsequent drop in ultrafine mode particle number concentration could be explained by coagulation. The observed particle growth rate of 2.1±0.1 nm/h was largely attributed to the condensation of measured H2SO4, assuming neutralization by ammonia.

  15. Polarization resolved angular optical scattering of aerosol particles

    NASA Astrophysics Data System (ADS)

    Redding, B.; Pan, Y.; Wang, C.; Videen, G.; Cao, Hui

    2014-05-01

    Real-time detection and identification of bio-aerosol particles are crucial for the protection against chemical and biological agents. The strong elastic light scattering properties of airborne particles provides a natural means for rapid, non-invasive aerosol characterization. Recent theoretical predictions suggested that variations in the polarization dependent angular scattering cross section could provide an efficient means of classifying different airborne particles. In particular, the polarization dependent scattering cross section of aggregate particles is expected to depend on the shape of the primary particles. In order to experimentally validate this prediction, we built a high throughput, sampling system, capable of measuring the polarization resolved angular scattering cross section of individual aerosol particles flowing through an interrogating volume with a single shot of laser pulse. We calibrated the system by comparing the polarization dependent scattering cross section of individual polystyrene spheres with that predicted by Mie theory. We then used the system to study different particles types: Polystyrene aggregates composed 500 nm spheres and Bacillus subtilis (BG, Anthrax simulant) spores composed of elongated 500 nm × 1000 nm cylinder-line particles. We found that the polarization resolved scattering cross section depends on the shape of the constituent elements of the aggregates. This work indicates that the polarization resolved scattering cross section could be used for rapid discrimination between different bio-aerosol particles.

  16. Optical measurement of medical aerosol media parameters

    NASA Astrophysics Data System (ADS)

    Sharkany, Josif P.; Zhytov, Nikolay B.; Sichka, Mikhail J.; Lemko, Ivan S.; Pintye, Josif L.; Chonka, Yaroslav V.

    2000-07-01

    The problem of aerosol media parameters measurements are presented in the work and these media are used for the treatment of the patients with bronchial asthma moreover we show the results of the development and the concentration and dispersity of the particles for the long-term monitoring under such conditions when the aggressive surroundings are available. The system for concentration measurements is developed, which consists of two identical photometers permitting to carry out the measurements of the transmission changes and the light dispersion depending on the concentration of the particles. The given system permits to take into account the error, connected with the deposition of the salt particles on the optical windows and the mirrors in the course of the long-term monitoring. For the controlling of the dispersity of the aggressive media aerosols the optical system is developed and used for the non-stop analysis of the Fure-spectra of the aerosols which deposit on the lavsan film. The registration of the information is performed with the help of the rule of the photoreceivers or CCD-chamber which are located in the Fure- plane. With the help of the developed optical system the measurements of the concentration and dispersity of the rock-salt aerosols were made in the medical mines of Solotvino (Ukraine) and in the artificial chambers of the aerosol therapy.

  17. Characteristics of aerosolized ice forming marine biogenic particles

    NASA Astrophysics Data System (ADS)

    Alpert, Peter A.

    Ice particles are ubiquitous in the atmosphere existing as the sole constituents of glaciated cirrus clouds or coexisting with supercooled liquid droplets in mixed-phase clouds. Aerosol particles serving as heterogeneous ice nuclei for ice crystal formation impact the global radiative balance by modification of cloud radiative properties, and thus climate. Atmospheric ice formation is not a well understood process and represents great uncertainty for climate prediction. The oceans which cover the majority of the earth's surface host nearly half the total global primary productivity and contribute to the greatest aerosol production by mass. However, the effect of biological activity on particle aerosolization, particle composition, and ice nucleation is not well established. This dissertation investigates the link between marine biological activity, aerosol particle production, physical/chemical particle characteristics, and ice nucleation under controlled laboratory conditions. Dry and humidified aerosol size distributions of particles from bursting bubbles generated by plunging water jets and aeration through frits in a seawater mesocosm containing bacteria and/or phytoplankton cultures, were measured as a function of biological activity. Total particle production significantly increases primarily due to enhanced aerosolization of particles ≤100 nm in diameter attributable to the presence and growth of phytoplankton. Furthermore, hygroscopicity measurements indicate primary organic material associated with the sea salt particles, providing additional evidence for the importance of marine biological activity for ocean derived aerosol composition. Ice nucleation experiments show that these organic rich particles nucleate ice efficiently in the immersion and deposition modes, which underscores their importance in mixed-phase and cirrus cloud formation processes. In separate ice nucleation experiments employing pure cultures of Thalassiosira pseudonana, Nannochloris

  18. Long-term real-time measurements of aerosol particle composition in Beijing, China: seasonal variations, meteorological effects, and source analysis

    NASA Astrophysics Data System (ADS)

    Sun, Y. L.; Wang, Z. F.; Du, W.; Zhang, Q.; Wang, Q. Q.; Fu, P. Q.; Pan, X. L.; Li, J.; Jayne, J.; Worsnop, D. R.

    2015-09-01

    High concentrations of fine particles (PM2.5) are frequently observed during all seasons in Beijing, China, leading to severe air pollution and human health problems in this megacity. In this study, we conducted real-time measurements of non-refractory submicron aerosol (NR-PM1) species (sulfate, nitrate, ammonium, chloride, and organics) in Beijing using an Aerodyne Aerosol Chemical Speciation Monitor for 1 year, from July 2011 to June 2012. This is the first long-term, highly time-resolved (~ 15 min) measurement of fine particle composition in China. The seasonal average (±1σ) mass concentration of NR-PM1 ranged from 52 (±49) μg m-3 in the spring season to 62 (±49) μg m-3 in the summer season, with organics being the major fraction (40-51 %), followed by nitrate (17-25 %) and sulfate (12-17 %). Organics and chloride showed pronounced seasonal variations, with much higher concentrations in winter than in the other seasons, due to enhanced coal combustion emissions. Although the seasonal variations of secondary inorganic aerosol (SIA, i.e., sulfate + nitrate + ammonium) concentrations were not significant, higher contributions of SIA were observed in summer (57-61 %) than in winter (43-46 %), indicating that secondary aerosol production is a more important process than primary emissions in summer. Organics presented pronounced diurnal cycles that were similar among all seasons, whereas the diurnal variations of nitrate were mainly due to the competition between photochemical production and gas-particle partitioning. Our data also indicate that high concentrations of NR-PM1 (> 60 μg m-3) are usually associated with high ambient relative humidity (RH) (> 50 %) and that severe particulate pollution is characterized by different aerosol composition in different seasons. All NR-PM1 species showed evident concentration gradients as a function of wind direction, generally with higher values associated with wind from the south, southeast or east. This was consistent

  19. Satellite Remote Sensing: Aerosol Measurements

    NASA Technical Reports Server (NTRS)

    Kahn, Ralph A.

    2013-01-01

    Aerosols are solid or liquid particles suspended in the air, and those observed by satellite remote sensing are typically between about 0.05 and 10 microns in size. (Note that in traditional aerosol science, the term "aerosol" refers to both the particles and the medium in which they reside, whereas for remote sensing, the term commonly refers to the particles only. In this article, we adopt the remote-sensing definition.) They originate from a great diversity of sources, such as wildfires, volcanoes, soils and desert sands, breaking waves, natural biological activity, agricultural burning, cement production, and fossil fuel combustion. They typically remain in the atmosphere from several days to a week or more, and some travel great distances before returning to Earth's surface via gravitational settling or washout by precipitation. Many aerosol sources exhibit strong seasonal variability, and most experience inter-annual fluctuations. As such, the frequent, global coverage that space-based aerosol remote-sensing instruments can provide is making increasingly important contributions to regional and larger-scale aerosol studies.

  20. The Life Cycle of Stratospheric Aerosol Particles

    NASA Technical Reports Server (NTRS)

    Hamill, Patrick; Jensen, Eric J.; Russell, P. B.; Bauman, Jill J.

    1997-01-01

    This paper describes the life cycle of the background (nonvolcanic) stratospheric sulfate aerosol. The authors assume the particles are formed by homogeneous nucleation near the tropical tropopause and are carried aloft into the stratosphere. The particles remain in the Tropics for most of their life, and during this period of time a size distribution is developed by a combination of coagulation, growth by heteromolecular condensation, and mixing with air parcels containing preexisting sulfate particles. The aerosol eventually migrates to higher latitudes and descends across isentropic surfaces to the lower stratosphere. The aerosol is removed from the stratosphere primarily at mid- and high latitudes through various processes, mainly by isentropic transport across the tropopause from the stratosphere into the troposphere.

  1. Submicron Aerosol Particle Losses in Metalized Bags.

    NASA Astrophysics Data System (ADS)

    Lecinski, Alice

    1980-07-01

    Two new types of conducting bags were tested for aerosol particle storage and sampling, a 3M Company Velostat bag and a bag constructed from 3M Type 2100 Static Shielding Film. The half-lives of unipolar, unit-charged 0.025 m, 0.050 m and 0.090 m sized aerosol particles stored in the Velostat bag and the film bag were 130, 190 and 270 min and 40, 70 and 180 min, respectively. These results depend upon the history of bag filling. The values given here apply to bags which had not previously been filled on the day of experimentation. The lifetimes exhibited by the aerosol particles stored in the Velostat bag are the longest found to data.

  2. New apparatus of single particle trap system for aerosol visualization

    NASA Astrophysics Data System (ADS)

    Higashi, Hidenori; Fujioka, Tomomi; Endo, Tetsuo; Kitayama, Chiho; Seto, Takafumi; Otani, Yoshio

    2014-08-01

    Control of transport and deposition of charged aerosol particles is important in various manufacturing processes. Aerosol visualization is an effective method to directly observe light scattering signal from laser-irradiated single aerosol particle trapped in a visualization cell. New single particle trap system triggered by light scattering pulse signal was developed in this study. The performance of the device was evaluated experimentally. Experimental setup consisted of an aerosol generator, a differential mobility analyzer (DMA), an optical particle counter (OPC) and the single particle trap system. Polystylene latex standard (PSL) particles (0.5, 1.0 and 2.0 μm) were generated and classified according to the charge by the DMA. Singly charged 0.5 and 1.0 μm particles and doubly charged 2.0 μm particles were used as test particles. The single particle trap system was composed of a light scattering signal detector and a visualization cell. When the particle passed through the detector, trigger signal with a given delay time sent to the solenoid valves upstream and downstream of the visualization cell for trapping the particle in the visualization cell. The motion of particle in the visualization cell was monitored by CCD camera and the gravitational settling velocity and the electrostatic migration velocity were measured from the video image. The aerodynamic diameter obtained from the settling velocity was in good agreement with Stokes diameter calculated from the electrostatic migration velocity for individual particles. It was also found that the aerodynamic diameter obtained from the settling velocity was a one-to-one function of the scattered light intensity of individual particles. The applicability of this system will be discussed.

  3. Aerosol Classification using Airborne High Spectral Resolution Lidar Measurements

    NASA Astrophysics Data System (ADS)

    Burton, S. P.; Ferrare, R. A.; Hostetler, C. A.; Hair, J. W.; Obland, M. D.; Rogers, R.; Butler, C. F.; Cook, A.; Harper, D.; Froyd, K. D.

    2011-12-01

    The NASA Langley Research Center (LaRC) airborne High Spectral Resolution Lidar (HSRL) on the NASA B200 aircraft has acquired extensive datasets of aerosol extinction (532 nm), aerosol optical thickness (AOT) (532 nm), backscatter (532 and 1064 nm), and depolarization (532 and 1064 nm) profiles during 18 field missions that have been conducted over North America since 2006. The lidar measurements of aerosol intensive parameters (lidar ratio, depolarization, backscatter color ratio, spectral depolarization ratio) are shown to vary with location and aerosol type. A methodology based on observations of known aerosol types is used to qualitatively classify the extensive set of HSRL aerosol measurements into eight separate types. Several examples are presented showing how the aerosol intensive parameters vary with aerosol type and how these aerosols are classified according to this new methodology. The HSRL-based classification reveals vertical variability of aerosol types during the NASA ARCTAS field experiment conducted over Alaska and northwest Canada during 2008. In two examples derived from flights conducted during ARCTAS, the HSRL classification of biomass burning smoke is shown to be consistent with aerosol types derived from coincident airborne in situ measurements of particle size and composition. The HSRL retrievals of aerosol optical thickness and inferences of aerosol types are used to apportion aerosol optical thickness to aerosol type; results of this analysis are shown for several experiments.

  4. Reactions and mass spectra of complex particles using Aerosol CIMS

    NASA Astrophysics Data System (ADS)

    Hearn, John D.; Smith, Geoffrey D.

    2006-12-01

    Aerosol chemical ionization mass spectrometry (CIMS) is used both on- and off-line for the analysis of complex laboratory-generated and ambient particles. One of the primary advantages of Aerosol CIMS is the low degree of ion fragmentation, making this technique well suited for investigating the reactivity of complex particles. To demonstrate the usefulness of this "soft" ionization, particles generated from meat cooking were reacted with ozone and the composition was monitored as a function of reaction time. Two distinct kinetic regimes were observed with most of the oleic acid in these particles reacting quickly but with 30% appearing to be trapped in the complex mixture. Additionally, detection limits are measured to be sufficiently low (100-200 ng/m3) to detect some of the more abundant constituents in ambient particles, including sulfate, which is measured in real-time at 1.2 [mu]g/m3. To better characterize complex aerosols from a variety of sources, a novel off-line collection method was also developed in which non-volatile and semi-volatile organics are desorbed from particles and concentrated in a cold U-tube. Desorption from the U-tube followed by analysis with Aerosol CIMS revealed significant amounts of nicotine in cigarette smoke and levoglucosan in oak and pine smoke, suggesting that this may be a useful technique for monitoring particle tracer species. Additionally, secondary organic aerosol formed from the reaction of ozone with R-limonene and volatile organics from orange peel were analyzed off-line showing large molecular weight products (m/z > 300 amu) that may indicate the formation of oligomers. Finally, mass spectra of ambient aerosol collected offline reveal a complex mixture of what appears to be highly processed organics, some of which may contain nitrogen.

  5. Evaluation of Aerosol Mixing State Classes in the GISS Modele-matrix Climate Model Using Single-particle Mass Spectrometry Measurements

    NASA Technical Reports Server (NTRS)

    Bauer, Susanne E.; Ault, Andrew; Prather, Kimberly A.

    2013-01-01

    Aerosol particles in the atmosphere are composed of multiple chemical species. The aerosol mixing state, which describes how chemical species are mixed at the single-particle level, provides critical information on microphysical characteristics that determine the interaction of aerosols with the climate system. The evaluation of mixing state has become the next challenge. This study uses aerosol time-of-flight mass spectrometry (ATOFMS) data and compares the results to those of the Goddard Institute for Space Studies modelE-MATRIX (Multiconfiguration Aerosol TRacker of mIXing state) model, a global climate model that includes a detailed aerosol microphysical scheme. We use data from field campaigns that examine a variety of air mass regimens (urban, rural, and maritime). At all locations, polluted areas in California (Riverside, La Jolla, and Long Beach), a remote location in the Sierra Nevada Mountains (Sugar Pine) and observations from Jeju (South Korea), the majority of aerosol species are internally mixed. Coarse aerosol particles, those above 1 micron, are typically aged, such as coated dust or reacted sea-salt particles. Particles below 1 micron contain large fractions of organic material, internally-mixed with sulfate and black carbon, and few external mixtures. We conclude that observations taken over multiple weeks characterize typical air mass types at a given location well; however, due to the instrumentation, we could not evaluate mass budgets. These results represent the first detailed comparison of single-particle mixing states in a global climate model with real-time single-particle mass spectrometry data, an important step in improving the representation of mixing state in global climate models.

  6. Evaluation of aerosol mixing state classes in the GISS modelE-MATRIX climate model using single-particle mass spectrometry measurements

    NASA Astrophysics Data System (ADS)

    Bauer, Susanne E.; Ault, Andrew; Prather, Kimberly A.

    2013-09-01

    Aerosol particles in the atmosphere are composed of multiple chemical species. The aerosol mixing state, which describes how chemical species are mixed at the single-particle level, provides critical information on microphysical characteristics that determine the interaction of aerosols with the climate system. The evaluation of mixing state has become the next challenge. This study uses aerosol time-of-flight mass spectrometry (ATOFMS) data and compares the results to those of the Goddard Institute for Space Studies modelE-MATRIX (Multiconfiguration Aerosol TRacker of mIXing state) model, a global climate model that includes a detailed aerosol microphysical scheme. We use data from field campaigns that examine a variety of air mass regimens (urban, rural, and maritime). At all locations, polluted areas in California (Riverside, La Jolla, and Long Beach), a remote location in the Sierra Nevada Mountains (Sugar Pine) and observations from Jeju (South Korea), the majority of aerosol species are internally mixed. Coarse aerosol particles, those above 1 µm, are typically aged, such as coated dust or reacted sea-salt particles. Particles below 1 µm contain large fractions of organic material, internally mixed with sulfate and black carbon, and few external mixtures. We conclude that observations taken over multiple weeks characterize typical air mass types at a given location well; however, due to the instrumentation, we could not evaluate mass budgets. These results represent the first detailed comparison of single-particle mixing states in a global climate model with real-time single-particle mass spectrometry data, an important step in improving the representation of mixing state in global climate models.

  7. Vapor scavenging by atmospheric aerosol particles

    SciTech Connect

    Andrews, E.

    1996-05-01

    Particle growth due to vapor scavenging was studied using both experimental and computational techniques. Vapor scavenging by particles is an important physical process in the atmosphere because it can result in changes to particle properties (e.g., size, shape, composition, and activity) and, thus, influence atmospheric phenomena in which particles play a role, such as cloud formation and long range transport. The influence of organic vapor on the evolution of a particle mass size distribution was investigated using a modified version of MAEROS (a multicomponent aerosol dynamics code). The modeling study attempted to identify the sources of organic aerosol observed by Novakov and Penner (1993) in a field study in Puerto Rico. Experimentally, vapor scavenging and particle growth were investigated using two techniques. The influence of the presence of organic vapor on the particle`s hydroscopicity was investigated using an electrodynamic balance. The charge on a particle was investigated theoretically and experimentally. A prototype apparatus--the refractive index thermal diffusion chamber (RITDC)--was developed to study multiple particles in the same environment at the same time.

  8. A novel approach for the characterization of transport and optical properties of aerosol particles near sources - Part I: Measurement of particle backscatter coefficient maps with a scanning UV lidar

    NASA Astrophysics Data System (ADS)

    Behrendt, Andreas; Pal, Sandip; Wulfmeyer, Volker; Valdebenito B., Álvaro M.; Lammel, Gerhard

    2011-05-01

    The physical and chemical properties of aerosols emitted from a livestock farm were determined by a novel approach which combines high-resolution lidar measurements (0.33 s, 30 m) with simulations of a microphysics-chemistry-transport model. This first of two companion papers describes the scanning lidar measurements of optical particle properties. The lidar system employed laser radiation at a wavelength of 355 nm with a power of 9 W and a pulse repetition rate of 30 Hz. The laser beam was expanded before transmission to the atmosphere so that it became eye-safe at distances >270 m to the lidar. The elastic backscatter signal was detected with a resolution of 0.033 s and 3 m. A receiving telescope with a primary-mirror diameter of 40 cm was used. For this system, we developed a novel method for two-dimensional retrievals of the particle backscatter coefficient. With this set up and approach, the lidar was able to identify the aerosol plume up to a range of ˜2.5 km from the source, a farm in northern Germany, in daytime. The measurements confirm that the optical particle properties of the emission plume vary largely with distance from the source and that the maximum particle backscatter coefficient is found away from the source. Within a close-to-horizontal scan (elevation angle of 2.3°), we found a mean particle backscatter coefficient of 1.5·10 -5 m -1 sr -1 inside the plume between 1.5 and 2.0 km distance from the source. Subtraction of the mean particle backscatter coefficient of the background aerosol present in this case (4.1·10 -6 m -1 sr -1) yields a particle backscatter coefficient of the livestock aerosols of 1.1·10 -5 m -1 sr -1. The limited extend of the plume is revealed with the scanning lidar: Scans with a slightly higher elevation angle of 4.8° did not pick up the plume.

  9. Measurement of aerosol particles, gases and flux radiation in the Pico de Orizaba National Park, and its relationship to air pollution transport

    NASA Astrophysics Data System (ADS)

    Márquez, C.; Castro, T.; Muhlia, A.; Moya, M.; Martínez-Arroyo, A.; Báez, A.

    Continuous atmospheric measurements were carried out at the Pico de Orizaba National Park (PONP), Mexico, in order to evaluate the characteristics and sources of air quality. This action allowed one to identify specific threats for the effective protection of natural resources and biodiversity. Results show the presence of particles and polluted gases transported by winds from the urban zones nearby (cities of Mexico, Puebla and Tlaxcala), as well as their measurable influence on the optical properties of the park environment. Nitrogen dioxide, carbon monoxide and sulfur dioxide show a daily pattern suggesting an influence of pollution generated by anthropogenic processes. Average concentration of SO 2 was higher than recorded at the southern part of Mexico City. Ozone concentrations ranging from 0.035 to 0.06 ppm suggest residual or background ozone character. Back trajectory analysis of air parcels arriving at the site confirm pollution caused by biomass burning and mass transport from urban zones. The SO 42-/TC ratio exhibited values (0.88±0.33) similar to urban areas. Ratios BC/TC and OC/BC for PONP are similar to those reported as influenced by burning emissions of fossil fuels. Typical rural aerosols were also found at the site, and sulfate and ammonium concentrations were correlated. The most predominating mode in surface particles size distribution was at 0.32 μm with no significant presence of coarse particles. Total carbon (OC+BC) content of fine particle mass (PM less than 1 μm) comprised, on average, 75%. Optical properties retrieved from photometric data show intermittent influence from urban pollution. Time periods with low absorbing particles, great visibility and abundance of small particles alternating with short times with bigger particles and high turbidity indicated by the optical depth.

  10. Intercomparison between a single particle soot photometer and evolved gas analysis in an industrial area in Japan: Implications for the consistency of soot aerosol mass concentration measurements

    NASA Astrophysics Data System (ADS)

    Miyakawa, T.; Kanaya, Y.; Komazaki, Y.; Taketani, F.; Pan, X.; Irwin, M.; Symonds, J.

    2016-02-01

    Mass concentrations of soot (typically comprising black and elemental carbon; BC and EC, respectively) aerosols, were measured at Yokosuka city, an industrial region in Japan in the early summer of 2014. The results of laser-induced incandescence (LII) and evolved gas analysis (EGA) techniques were compared using a single particle soot photometer (SP2) and semi-continuous elemental/organic carbon analyzer (EC/OC analyzer), respectively. We revisited the procedure of SP2 calibration with a focus on investigating the relationship between LII intensity (SLII) and refractory BC (rBC) mass per particle (mPP) for some BC-proxies in the laboratory, as well as for ambient rBC particles in order to discuss the uncertainty of the SP2. It was found that the mPP-SLII for the fullerene soot and carbon black particles agreed well within 3% and 10%, respectively, with that for ambient rBC particles. This is the first time to suggest the use of carbon black as a reference material. We also found that the mPP-SLII for the aqueous deflocculated Acheson graphite particles with the correction factor given by Baumgardner et al. (2012) was still biased by around +20% to that for ambient rBC particles. EC quantified by the semi-continuous EC/OC analyzer using a thermal-protocol similar to that of Interagency Monitoring of Protected Visual Environments (IMPROVE-like), systematically showed higher concentrations than rBC measured by the SP2. The uncertainties related to SP2 cannot fully account for this difference. This result was likely caused by the contribution of charred organic materials to EC, which can be affected significantly by thermal-protocols for the EGA. The consistency and differences between rBC and EC are discussed with regard to comparing their respective mass concentrations.

  11. Aerosol Classification from High Spectral Resolution Lidar Measurements

    NASA Astrophysics Data System (ADS)

    Burton, S. P.; Hair, J. W.; Ferrare, R. A.; Hostetler, C. A.; Kahnert, M.; Vaughan, M. A.; Cook, A. L.; Harper, D. B.; Berkoff, T.; Seaman, S. T.; Collins, J. E., Jr.; Fenn, M. A.; Rogers, R. R.

    2015-12-01

    The NASA Langley airborne High Spectral Resolution Lidars, HSRL-1 and HSRL-2, have acquired large datasets of vertically resolved aerosol extinction, backscatter, and depolarization during >30 airborne field missions since 2006. The lidar measurements of aerosol intensive parameters like lidar ratio and color ratio embed information about intrinsic aerosol properties, and are combined to qualitatively classify HSRL aerosol measurements into aerosol types. Knowledge of aerosol type is important for assessing aerosol radiative forcing, and can provide useful information for source attribution studies. However, atmospheric aerosol is frequently not a single pure type, but instead is a mixture, which affects the optical and radiative properties of the aerosol. We show that aerosol intensive parameters measured by lidar can be understood using mixing rules for cases of external mixing. Beyond coarse classification and mixing between classes, variations in the lidar aerosol intensive parameters provide additional insight into aerosol processes and composition. This is illustrated by depolarization measurements at three wavelengths, 355 nm, 532 nm, and 1064 nm, made by HSRL-2. Particle depolarization ratio is an indicator of non-spherical particles. Three cases each have a significantly different spectral dependence of the depolarization ratio, related to the size of the depolarizing particles. For two dust cases, large non-spherical particles account for the depolarization of the lidar light. The spectral dependence reflects the size distribution of these particles and reveals differences in the transport histories of the two plumes. For a smoke case, the depolarization is inferred to be due to the presence of small coated soot aggregates. Interestingly, the depolarization at 355 nm is similar for this smoke case compared to the dust cases, having potential implications for the upcoming EarthCARE satellite, which will measure particle depolarization ratio only at 355 nm.

  12. Comparison of the DiSCmini aerosol monitor to a handheld condensation particle counter and a scanning mobility particle sizer for submicrometer sodium chloride and metal aerosols.

    PubMed

    Mills, Jessica B; Park, Jae Hong; Peters, Thomas M

    2013-01-01

    We evaluated the robust, lightweight DiSCmini (DM) aerosol monitor for its ability to measure the concentration and mean diameter of submicrometer aerosols. Tests were conducted with monodispersed and polydispersed aerosols composed of two particle types (sodium chloride [NaCl] and spark-generated metal particles, which simulate particles found in welding fume) at three different steady-state concentration ranges (Low, <10(3); Medium, 10(3)-10(4); and High, >10(4) particles/cm(3)). Particle number concentration, lung deposited surface area (LDSA) concentration, and mean size measured with the DM were compared with those measured with reference instruments, a scanning mobility particle sizer (SMPS), and a handheld condensation particle counter (CPC). Particle number concentrations measured with the DM were within 16% of those measured by the CPC for polydispersed aerosols. Poorer agreement was observed for monodispersed aerosols (±35% for most tests and +101% for 300-nm NaCl). LDSA concentrations measured by the DM were 96% to 155% of those estimated with the SMPS. The geometric mean diameters measured with the DM were within 30% of those measured with the SMPS for monodispersed aerosols and within 25% for polydispersed aerosols (except for the case when the aerosol contained a substantial number of particles larger than 300 nm). The accuracy of the DM is reasonable for particles smaller than 300 nm, but caution should be exercised when particles larger than 300 nm are present. [Supplementary materials are available for this article. Go to the publisher's online edition of the Journal of Occupational and Environmental Hygiene for the following free supplemental resources: manufacturer-reported capabilities of instruments used, and information from the SMPS measurements for polydispersed test particles.].

  13. Single-particle laser-induced-fluorescence spectra of biological and other organic-carbon aerosols in the atmosphere: Measurements at New Haven, Connecticut, and Las Cruces, New Mexico

    NASA Astrophysics Data System (ADS)

    Pan, Yong-Le; Pinnick, Ronald G.; Hill, Steven C.; Rosen, James M.; Chang, Richard K.

    2007-12-01

    This study focuses on organic carbon (OC) aerosols, including natural biological aerosols, in the Earth's troposphere, and on laser-induced fluorescence (LIF) spectral methods for studying these aerosols. LIF spectra of atmospheric OC and biological aerosols (having diameters greater than approximately 3 μm) measured at New Haven, Connecticut, and Las Cruces, New Mexico, are reported. A hierarchical clustering method was used to cluster approximately 90% of the single-particle LIF spectra into 8-10 groups. Some of these groups have spectra that are similar to spectra of some important classes of atmospheric aerosol, such as humic/fulvic acids and humic-like substances, bacteria, cellulose, marine aerosol, and polycyclic aromatic hydrocarbons (PAH). A comparison with previous measurements made at Adelphi, Maryland, reveals that the most highly populated clusters found at Adelphi, and some of the less populated ones, also appear in the LIF spectra at New Haven and Las Cruces, even though the regional climates at these locations is different (New England/Atlantic Coastal, for New Haven and Adelphi, and Chihuahuan Desert for Las Cruces), and the measurements were made in different seasons. The results are consistent with some (perhaps most) of the fluorors in OC and biological atmospheric aerosols being common to these three sites. On average, spectra characteristic of humic/fulvic acids and humic-like substances (HULIS) comprise 28-43% of fluorescent particles at all three sites; whereas cellulose-like spectra contribute only 1-3%.

  14. The stratospheric aerosol particle measurement by balloon at Syowa Station (69.00 deg S, 39.35 deg E): Outline of special sonde (rubber) campaign JARE 24

    NASA Technical Reports Server (NTRS)

    Iwasaka, Y.; Morita, T.; Itoh, T.; Shibazaki, K.; Makino, Y.; Tanaka, T.; Tsukamura, K.; Yano, T.; Kondoh, K.; Iwashita, G.

    1985-01-01

    During the period of AMA (Antarctic Middle Atmosphere), various style balloons were used to measure atmospheric parameters at Syowa Station (69.00 deg S, 39.35 deg E), Antarctica. The measurements which were made using balloons specially designed to monitor stratospheric aerosol particles are discussed. This type balloon was first used by JARE (Japan Antarctic Research Expedition) 24th Team in 1983. Until that time, the Japan Antarctic Research Expedition Team had been using only a large plastic balloon to monitor various minor constituents in the stratosphere. The plastic balloon was very useful, but it took a long time to arrange a balloon launching. Additionally, launching time strongly depended on weather conditions. A timely launching of the balloon was carried out with this specially designed sonde.

  15. Development and Characterization of a Thermodenuder for Aerosol Volatility Measurements

    SciTech Connect

    Dr. Timothy Onasch

    2009-09-09

    This SBIR Phase I project addressed the critical need for improved characterization of carbonaceous aerosol species in the atmosphere. The proposed work focused on the development of a thermodenuder (TD) system capable of systematically measuring volatility profiles of primary and secondary organic aerosol species and providing insight into the effects of absorbing and nonabsorbing organic coatings on particle absorption properties. This work provided the fundamental framework for the generation of essential information needed for improved predictions of ambient aerosol loadings and radiative properties by atmospheric chemistry models. As part of this work, Aerodyne Research, Inc. (ARI) continued to develop and test, with the final objective of commercialization, an improved thermodenuder system that can be used in series with any aerosol instrument or suite of instruments (e.g., aerosol mass spectrometers-AMS, scanning mobility particle sizers-SMPS, photoacoustic absorption spectrometers-PAS, etc.) to obtain aerosol chemical, physical, and optical properties as a function of particle volatility. In particular, we provided the proof of concept for the direct coupling of our improved TD design with a full microphysical model to obtain volatility profiles for different organic aerosol components and to allow for meaningful comparisons between different TD-derived aerosol measurements. In a TD, particles are passed through a heated zone and a denuding (activated charcoal) zone to remove semi-volatile material. Changes in particle size, number concentration, optical absorption, and chemical composition are subsequently detected with aerosol instrumentation. The aerosol volatility profiles provided by the TD will strengthen organic aerosol emission inventories, provide further insight into secondary aerosol formation mechanisms, and provide an important measure of particle absorption (including brown carbon contributions and identification, and absorption enhancements

  16. Aerosol and Plasma Measurements in Noctilucent Clouds

    NASA Technical Reports Server (NTRS)

    Robertson, Scott

    2000-01-01

    The purpose of this project was to develop rocket-borne probes to detect charged aerosol layers in the mesosphere. These include sporadic E layers, which have their origin in meteoric dust, and noctilucent clouds, which form in the arctic summer and are composed of ice crystals. The probe being developed consists of a charge collecting patch connected to a sensitive electrometer which measures the charge deposited on the patch by impacting aerosols. The ambient electrons and light ions in the mesosphere are prevented from being collected by a magnetic field. The magnetic force causes these lighter particles to turn so that they miss the collecting patch.

  17. Measurements of Semi-volatile Aerosol and Its Effect on Aerosol Optical Properties During Southern Oxidant and Aerosol Study

    NASA Astrophysics Data System (ADS)

    Khlystov, A.; Grieshop, A. P.; Saha, P.; Subramanian, R.

    2013-12-01

    Semi-volatile compounds, including particle-bound water, comprise a large part of aerosol mass and have a significant influence on aerosol lifecycle and its optical properties. Understanding the properties of semi-volatile compounds, especially those pertaining to gas/aerosol partitioning, is of critical importance for our ability to predict concentrations and properties of ambient aerosol. A set of state-of-the-art instruments was deployed at the SEARCH site near Centerville, AL during the Southern Oxidant and Aerosol Study (SOAS) campaign in summer 2013 to measure the effect of temperature and relative humidity on aerosol size distribution, composition and optical properties. Light scattering and absorption by temperature- and humidity-conditioned aerosols was measured using three photo-acoustic extinctiometers (PAX) at three wavelengths (405 nm, 532 nm, and 870 nm). In parallel to these measurements, a long residence time temperature-stepping thermodenuder and a variable residence time constant temperature thermodenuder in combination with three SMPS systems and an Aerosol Chemical Speciation Monitor (ACSM) were used to assess aerosol volatility and kinetics of aerosol evaporation. It was found that both temperature and relative humidity have a strong effect on aerosol optical properties. The variable residence time thermodenuder data suggest that aerosol equilibrated fairly quickly, within 2 s, in contrast to other ambient observations. Preliminary analysis show that approximately 50% and 90% of total aerosol mass evaporated at temperatures of 100 C and 180C, respectively. Evaporation varied substantially with ambient aerosol loading and composition and meteorology. During course of this study, T50 (temperatures at which 50% aerosol mass evaporates) varied from 60 C to more than 120 C.

  18. Particle Property Data Quality Flags for the MISR Aerosol Product

    NASA Astrophysics Data System (ADS)

    Gaitley, B. J.; Kahn, R. A.; Garay, M. J.

    2013-12-01

    The MISR instrument aboard the NASA Earth Observing System's Terra satellite has the unique capability to retrieve aerosol properties under favorable conditions. General aerosol type retrieval quality guidelines are provided in the MISR Data Quality Statement and related publications. The retrieved value of aerosol type is more sensitive to scene conditions than aerosol optical depth, and more difficult to validate, as there is very little coincident aerosol type validation data. Here we report on the steps we are taking to provide an aerosol-type data quality flag, to be provided with each individual retrieval result. Due to the lack of validation data for comparison, our main approach is to evaluate the self-consistency of aerosol type retrieval values for regions where particular aerosol types are known to dominate. Some factors affecting aerosol type retrieval quality that can be assessed pre-retrieval are the number of MISR cameras available, the range of scattering angles viewed, and surface conditions such as shallow water or seasonal coastal runoff. Factors that must be assessed post-retrieval include values of retrieved aerosol optical depth and the number and type of mixtures successfully passing the MISR algorithm acceptance criteria. Regional monthly plots with MISR measurements binned at 0.5 degree resolution and color-coded stratification of one or more parameters are the main tools for identifying locations and times where different aerosol types are retrieved. The statistics of individual MISR values such as mid-visible AOD, number and type of mixtures passing, number of cameras used, the range and maximum scattering angles, are studied as joint distributions on a region-by-region basis. From these, a synthesis of the self-consistency and agreement with expectation is made, effectively indicating the quality of the aerosol type constrains to the extent possible, and thresholds for assigning quality flags are assessed. Multiple-month summaries

  19. Reconciling satellite aerosol optical thickness and surface fine 5 particle mass through aerosol liquid water

    SciTech Connect

    V. Nguyen, Thien Khoi; Ghate, Virendra P.; Carlton, Annmarie G.

    2016-11-28

    Summertime aerosol optical thickness (AOT) over the Southeast U.S. is sharply enhanced over wintertime values. This seasonal pattern is unique and of particular interest because temperatures there have not warmed over the past 100 years. Patterns in surface fine particle mass are inconsistent with satellite reported AOT. In this work, we attempt to reconcile the spatial and temporal distribution of AOT over the U.S. with particle mass measurements at the surface by examining trends in aerosol liquid water (ALW), a particle constituent that scatters radiation affecting the satellite AOT, but is removed in mass measurements at routine surface monitoring sites. We employ the thermodynamic model ISORROPIAv2.1 to estimate ALW mass concentrations at IMRPOVE sites using measured ion mass concentrations and NARR meteorological data. Our findings suggest ALW provides a plausible explanation for the geographical and seasonal patterns in AOT and can reconcile previously noted discrepancies with surface mass measurements.

  20. Analysis of Ambient Aerosol Measurements During PROPHET 2001

    NASA Astrophysics Data System (ADS)

    Delia, A. E.; Garland, R.; Toohey, D. W.; Worsnop, D. R.; Allen, J. O.; Carroll, M. A.; Fortner, E.; Hengel, S.; Lilly, M.; Moody, J.; Huey, G.; Tanner, D.

    2002-12-01

    Aerosol size and composition were measured using an aerosol mass spectrometer, developed by Aerodyne Research, Inc., during PROPHET 2001 (Program for Research on Oxidants: PHotochemistry, Emissions and Transport). Our purpose in this study was to characterize chemical composition and size of ambient aerosols, investigate the effects of transport, and study aerosol microphysics. The site is located in a remote forested area of northern Michigan at the University of Michigan Biological Station, far from any large urban areas and surrounded primarily by deciduous forests. The aerosols at this site can be cataloged into four classes. The two principal classes are distinguished by meteorological conditions. Clean, northerly airflow produced low aerosol mass loadings dominated by organic species. More polluted southerly airflow brought higher aerosol mass loadings dominated by sulfate with an organic contribution. Under both of these conditions, aerosol existed almost entirely in the accumulation size mode of 300-600 nm. In addition to these principal aerosol types, small particle growth was observed on several occasions. It appears that these events occurred primarily during periods of low aerosol mass loading (i.e., northerly airflow) when the low aerosol number provided an opportunity for new particle formation and rapid growth. On at least one occasion, it appears that a large plume of sulfur dioxide that was converted to sulfuric acid near the site may be responsible for new particle formation. The fourth type of aerosol consisted of short events dominated by organic species, apparently diesel exhaust caused by local truck traffic. In addition to the overall aerosol characterization, comparisons with other measurements that affected the aerosol composition or characterized the air masses will be presented and the implications of these results for regional transport of aerosols will be discussed.

  1. Processing of aerosol particles within the Habshan pollution plume

    NASA Astrophysics Data System (ADS)

    Semeniuk, T. A.; Bruintjes, R.; Salazar, V.; Breed, D.; Jensen, T.; Buseck, P. R.

    2015-03-01

    The Habshan industrial site in the United Arab Emirates produces a regional-scale pollution plume associated with oil and gas processing, discharging high loadings of sulfates and chlorides into the atmosphere, which interact with the ambient aerosol population. Aerosol particles and trace gas chemistry at this site were studied on two flights in the summer of 2002. Measurements were collected along vertical plume profiles to show changes associated with atmospheric processing of particle and gas components. Close to the outlet stack, particle concentrations were over 10,000 cm-3, dropping to <2000 cm-3 in more dilute plume around 1500 m above the stack. Particles collected close to the stack and within the dilute plume were individually measured for size, morphology, composition, and mixing state using transmission electron microscopy coupled with energy-dispersive X-ray spectroscopy. Close to the stack, most coarse particles consisted of mineral dust and NaCl crystals from burning oil brines, while sulfate droplets dominated the fine mode. In more dilute plume, at least 1500 m above the stack, the particle spectrum was more diverse, with a significant increase in internally mixed particle types. Dilute plume samples consisted of coarse NaCl/silicate aggregates or NaCl-rich droplets, often with a sulfate component, while fine-fraction particles were of mixed cation sulfates, also internally mixed with nanospherical soot or silicates. Thus, both chloride and sulfate components of the pollution plume rapidly reacted with ambient mineral dust to form coated and aggregate particles, enhancing particle size, hygroscopicity, and reactivity of the coarse mode. The fine-fraction sulfate-bearing particles formed in the plume contribute to regional transport of sulfates, while coarse sulfate-bearing fractions locally reduced the SO2 loading through sedimentation. The chloride- and sulfate-bearing internally mixed particles formed in the plume markedly changed the

  2. Satellite measurements of tropospheric aerosols

    NASA Technical Reports Server (NTRS)

    Griggs, M.

    1981-01-01

    This investigation uses LANDSAT 2 radiance data and ground-truth measurements of the aerosol optical thickness, obtained previously from five inland sites, to study the usefulness and limitations of the near infrared radiance over inland bodies of water. The linear relationship between LANDSAT 2 MSS7 and aerosol content found in this study can be used to estimate the aerosol content with a standard deviation of 0.42N. Analysis of the data for MSS6 and MSS7 suggest that the larger uncertainty is mostly due to water turbidity, with little contribution from the adjacency effect. The relationship found is best applied to determine an average aerosol content over a period of time at a given target, or an area average at a given time over several targets close together.

  3. Composition and formation of organic aerosol particles in the Amazon

    NASA Astrophysics Data System (ADS)

    Pöhlker, C.; Wiedemann, K.; Sinha, B.; Shiraiwa, M.; Gunthe, S. S.; Artaxo, P.; Gilles, M. K.; Kilcoyne, A. L. D.; Moffet, R. C.; Smith, M.; Weigand, M.; Martin, S. T.; Pöschl, U.; Andreae, M. O.

    2012-04-01

    We applied scanning transmission X-ray microscopy with near edge X-ray absorption fine structure (STXM-NEXAFS) analysis to investigate the morphology and chemical composition of aerosol samples from a pristine tropical environment, the Amazon Basin. The samples were collected in the Amazonian rainforest during the rainy season and can be regarded as a natural background aerosol. The samples were found to be dominated by secondary organic aerosol (SOA) particles in the fine and primary biological aerosol particles (PBAP) in the coarse mode. Lab-generated SOA-samples from isoprene and terpene oxidation as well as pure organic compounds from spray-drying of aqueous solution were measured as reference samples. The aim of this study was to investigate the microphysical and chemical properties of a tropical background aerosol in the submicron size range and its internal mixing state. The lab-generated SOA and pure organic compounds occurred as spherical and mostly homogenous droplet-like particles, whereas the Amazonian SOA particles comprised a mixture of homogeneous droplets and droplets having internal structures due to atmospheric aging. In spite of the similar morphological appearance, the Amazon samples showed considerable differences in elemental and functional group composition. According to their NEXAFS spectra, three chemically distinct types of organic material were found and could be assigned to the following three categories: (1) particles with a pronounced carboxylic acid (COOH) peak similar to those of laboratory-generated SOA particles from terpene oxidation; (2) particles with a strong hydroxy (COH) signal similar to pure carbohydrate particles; and (3) particles with spectra resembling a mixture of the first two classes. In addition to the dominant organic component, the NEXAFS spectra revealed clearly resolved potassium (K) signals for all analyzed particles. During the rainy season and in the absence of anthropogenic influence, active biota is

  4. Polycyclic aromatic hydrocarbons in bulk PM2.5 and size-segregated aerosol particle samples measured in an urban environment.

    PubMed

    Park, Seung Shik; Kim, Young J; Kang, Chang Hee

    2007-05-01

    To analyze polycyclic aromatic hydrocarbons (PAHs) at an urban site in Seoul, South Korea, 24-hr ambient air PM2.5 samples were collected during five intensive sampling periods between November 1998 and December 1999. To determine the PAH size distribution, 3-day size-segregated aerosol samples were also collected in December 1999. Concentrations of the 16 PAHs in the PM2.5 particles ranged from 3.9 to 119.9 ng m(-3) with a mean of 24.3 ng m(-3). An exceptionally high concentration of PAHs( approximately 120 ng m(-3)) observed during a haze event in December 1999 was likely influenced more by diesel vehicle exhaust than by gasoline exhaust, as well as air stagnation, as evidenced by the low carbon monoxide/elemental carbon (CO/EC) ratio of 205 found in this study and results reported by previous studies. The total PAHs associated with the size-segregated particles showed unimodal distributions. Compared to the unimodal size distributions of PAHs with modal peaks at < 0.12 microm measured in highway tunnels in Los Angeles (Venkataraman and Friedlander, 1994), four- to six-ring PAHs in our study had unimodal size distributions, peaking at the larger size range of 0.28-0.53 microm, suggesting the coagulation of freshly emitted ultrafine particles during transport to the sampling site. Further, the fraction of PAHs associated with coarse particles(> 1.8 microm) increased as the molecular weight of the PAHs decreased due to volatilization of fine particles followed by condensation onto coarse particles.

  5. Single Particle Analysis of Ice Forming Aerosols

    NASA Astrophysics Data System (ADS)

    Cziczo, Daniel J.; Kulkarni, Gourihar; Pratt, Kerri; Pekour, Mikahil; Hallar, Gannet; McCubbin, Ian

    2010-05-01

    During January and February of 2010 ice forming aerosol particles were analyzed at Storm Peak Laboratory in north-central Colorado in the USA. Atmospheric particles were acquired through an isokinetic inlet during periods when free-tropospheric conditions with minimal local influence existed. The particles were then subject to low temperature and high relative humidity in order to mimic cloud formation conditions. Particles which nucleated ice were separated using a counterflow virtual impactor. The size and chemical composition of the ice nuclei was then characterized in situ using a single particle mass spectrometer . Samples were also collected for off line electron microscopic analysis. A particular emphasis was placed on determination of fractions associated with anthropogenic activity and biogenic components.

  6. Single particle multichannel bio-aerosol fluorescence sensor

    NASA Astrophysics Data System (ADS)

    Kaye, P. H.; Stanley, W. R.; Hirst, E.; Foot, E. V.; Baxter, K. L.; Barrington, S. J.

    2005-05-01

    We describe a prototype low-cost multi-channel aerosol fluorescence sensor designed for unattended deployment in medium to large area bio-aerosol detection networks. Individual airborne particles down to ~1μm in size are detected and sized by measurement of light scattered from a continuous-wave diode laser (660nm). This scatter signal is then used to trigger the sequential firing of two xenon sources which irradiate the particle with UV pulses at ~280 nm and ~370 nm, optimal for excitation of bio-fluorophores tryptophan and NADH (nicotinamide adenine dinucleotide) respectively. For each excitation wavelength, fluorescence is detected across two bands embracing the peak emissions of the same bio-fluorophores. Current measurement rates are up to ~125 particles/s, corresponding to all particles for concentrations up to 1.3 x 104 particles/l. Developments to increase this to ~500 particles/s are in hand. Device sensitivity is illustrated in preliminary data recorded from aerosols of E.coli, BG spores, and a variety of non-biological materials.

  7. Laboratory and Ambient Studies Using an Automated Semi-Continuous Single-Particle Aerosol Raman Spectrometer

    NASA Astrophysics Data System (ADS)

    Doughty, D., III; Hill, S. C.

    2015-12-01

    Single-particle Raman spectra can yield extensive information about in-situ ambient particulate composition. However, Raman spectral measurements of individual aerosol particles typically require collection of samples in the field followed by offline Raman spectral measurements in a laboratory. The process requires considerable operator time. We report results obtained with an automated, single-particle Aerosol Raman Spectrometer built by Battelle, which is the core of Battelle's Resource Effective Bioidentification System (REBS). This instrument collects aerosol particles onto a metallized polymer tape and simultaneously measures Raman spectra of particles obtained during the previous collection period. At the end of each collection period (typically 15 minutes), the tape is advanced and the next collection and measurement period is begun. In this way, particles are semi-continuously sampled and their Raman spectra are measured. We show laboratory data from different sizes of polystyrene latex spheres. We also show results from calcium sulfate particles, vehicular emission soot, and other particles. We discuss the influence of imaging time on the quality of the Raman spectra measured and on the ability of the instrument to resolve aerosol particles. Finally, we present results from an outdoor sampling period during the summer of 2015 where the instrument ran unattended for more than one week collecting particles and measuring their Raman spectra. We suggest that the routine use of such an automated particle-sampling instrument should increase our understanding of inorganic and organic aerosols including biological aerosols and sources and fates of these particles.

  8. Online derivatization for hourly measurements of gas- and particle-phase semi-volatile oxygenated organic compounds by thermal desorption aerosol gas chromatography (SV-TAG)

    NASA Astrophysics Data System (ADS)

    Isaacman, G.; Kreisberg, N. M.; Yee, L. D.; Worton, D. R.; Chan, A. W. H.; Moss, J. A.; Hering, S. V.; Goldstein, A. H.

    2014-12-01

    Laboratory oxidation studies have identified a large number of oxygenated organic compounds that can be used as tracers to understand sources and oxidation chemistry of atmospheric particulate matter. Quantification of these compounds in ambient environments has traditionally relied on low-time-resolution collection of filter samples followed by offline sample treatment with a derivatizing agent to allow analysis by gas chromatography of otherwise non-elutable organic chemicals with hydroxyl groups. We present here an automated in situ instrument for the measurement of highly polar organic semi-volatile and low-volatility compounds in both the gas- and particle-phase with hourly quantification of mass concentrations and gas-particle partitioning. The dual-cell semi-volatile thermal desorption aerosol gas chromatograph (SV-TAG) with derivatization collects particle-only and combined particle-plus-vapor samples on two parallel sampling cells that are analyzed in series by thermal desorption into helium saturated with derivatizing agent. Introduction of MSTFA (N-methyl-N-(trimethylsilyl)trifluoroacetamide), a silylating agent, yields complete derivatization of all tested compounds, including alkanoic acids, polyols, diacids, sugars, and multifunctional compounds. In laboratory tests, derivatization is found to be highly reproducible (< 3% variability). During field deployment, a regularly injected internal standard is used to correct for variability in detector response, consumption of the derivatization agent, desorption efficiency, and transfer losses. Error in quantification from instrument fluctuations is found to be less than 10% for hydrocarbons and less than 15% for all oxygenates for which a functionally similar internal standard is available, with an uncertainty of 20-25% in measurements of particle fraction. After internal standard corrections, calibration curves are found to be linear for all compounds over the span of 1 month, with comparable response on

  9. An aerosol particle containing enriched uranium encountered during routine sampling

    NASA Astrophysics Data System (ADS)

    Murphy, Daniel; Froyd, Karl; Evangeliou, NIkolaos; Stohl, Andreas

    2017-04-01

    The composition of single aerosol particles has been measured using a laser ionization mass spectrometer during the global Atmospheric Tomography mission. The measurements were targeting the background atmosphere, not radiochemical emissions. One sub-micron particle sampled at about 7 km altitude near the Aleutian Islands contained uranium with approximately 3% 235U. It is the only particle with enriched uranium out of millions of particles sampled over several decades of measurements with this instrument. The particle also contained vanadium, alkali metals, and organic material similar to that present in emissions from combustion of heavy oil. No zirconium or other metals that might be characteristic of nuclear reactors were present, probably suggesting a source other than Fukushima or Chernobyl. Back trajectories suggest several areas in Asia that might be sources for the particle.

  10. Biodiversity of Aerosolized Particles (Final Report)

    DTIC Science & Technology

    2015-01-01

    are obtained for each of 96 samples by collaborators at the Edgewood Chemical Biological Center [ECBC] using their Illumina Hi-Seq). 6) Assign each...Gallagher M, Kreidenweis SM, Bertram AK, Pöschl U. High concentrations of biological aerosol particles and ice nuclei during and after rain ...DRI Director’s Research Initiative DRUM Davis Rotating Unit for Monitoring ECBC Edgewood Chemical Biological Center EPA Environmental

  11. Development of Portable Aerosol Mobility Spectrometer for Personal and Mobile Aerosol Measurement.

    PubMed

    Kulkarni, Pramod; Qi, Chaolong; Fukushima, Nobuhiko

    2016-01-01

    We describe development of a Portable Aerosol Mobility Spectrometer (PAMS) for size distribution measurement of submicrometer aerosol. The spectrometer is designed for use in personal or mobile aerosol characterization studies and measures approximately 22.5 × 22.5 × 15 cm and weighs about 4.5 kg including the battery. PAMS uses electrical mobility technique to measure number-weighted particle size distribution of aerosol in the 10-855 nm range. Aerosol particles are electrically charged using a dual-corona bipolar corona charger, followed by classification in a cylindrical miniature differential mobility analyzer. A condensation particle counter is used to detect and count particles. The mobility classifier was operated at an aerosol flow rate of 0.05 L/min, and at two different user-selectable sheath flows of 0.2 L/min (for wider size range 15-855 nm) and 0.4 L/min (for higher size resolution over the size range of 10.6-436 nm). The instrument was operated in voltage stepping mode to retrieve the size distribution, which took approximately 1-2 minutes, depending on the configuration. Sizing accuracy and resolution were probed and found to be within the 25% limit of NIOSH criterion for direct-reading instruments (NIOSH 2012). Comparison of size distribution measurements from PAMS and other commercial mobility spectrometers showed good agreement. The instrument offers unique measurement capability for on-person or mobile size distribution measurements of ultrafine and nanoparticle aerosol.

  12. Development of Portable Aerosol Mobility Spectrometer for Personal and Mobile Aerosol Measurement

    PubMed Central

    Kulkarni, Pramod; Qi, Chaolong; Fukushima, Nobuhiko

    2017-01-01

    We describe development of a Portable Aerosol Mobility Spectrometer (PAMS) for size distribution measurement of submicrometer aerosol. The spectrometer is designed for use in personal or mobile aerosol characterization studies and measures approximately 22.5 × 22.5 × 15 cm and weighs about 4.5 kg including the battery. PAMS uses electrical mobility technique to measure number-weighted particle size distribution of aerosol in the 10–855 nm range. Aerosol particles are electrically charged using a dual-corona bipolar corona charger, followed by classification in a cylindrical miniature differential mobility analyzer. A condensation particle counter is used to detect and count particles. The mobility classifier was operated at an aerosol flow rate of 0.05 L/min, and at two different user-selectable sheath flows of 0.2 L/min (for wider size range 15–855 nm) and 0.4 L/min (for higher size resolution over the size range of 10.6–436 nm). The instrument was operated in voltage stepping mode to retrieve the size distribution, which took approximately 1–2 minutes, depending on the configuration. Sizing accuracy and resolution were probed and found to be within the 25% limit of NIOSH criterion for direct-reading instruments (NIOSH 2012). Comparison of size distribution measurements from PAMS and other commercial mobility spectrometers showed good agreement. The instrument offers unique measurement capability for on-person or mobile size distribution measurements of ultrafine and nanoparticle aerosol.

  13. Reconciling satellite aerosol optical thickness and surface fine particle mass through aerosol liquid water

    NASA Astrophysics Data System (ADS)

    Nguyen, Thien Khoi V.; Ghate, Virendra P.; Carlton, Annmarie G.

    2016-11-01

    Summertime aerosol optical thickness (AOT) over the southeast U.S. is sharply enhanced over wintertime values. This seasonal pattern is unique and of particular interest because temperatures there have not warmed over the past 100 years. Patterns in surface fine particle mass are inconsistent with satellite reported AOT. In this work, we attempt to reconcile the spatial and temporal distribution of AOT over the U.S. with particle mass measurements at the surface by examining trends in aerosol liquid water (ALW), a particle constituent that scatters radiation and affects satellite AOT but is removed in mass measurements at routine surface monitoring sites. We employ the thermodynamic model ISORROPIAv2.1 to estimate ALW mass concentrations at Interagency Monitoring of PROtected Visual Environments sites using measured ion mass concentrations and North American Regional Reanalysis meteorological data. Excellent agreement between Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations AOT and estimated ALW provides a plausible explanation for the discrepancies in the geographical patterns of AOT and aerosol mass measurements.

  14. Solar Mesosphere Explorer satellite measurements of el Chichon stratospheric aerosols. 2: Aerosol mass and size parameters

    NASA Technical Reports Server (NTRS)

    Eparvier, F. G.; Rusch, D. W.; Clancy, R. T.; Thomas, G. E.

    1994-01-01

    Spatially and temporally extensive observations of the stratospheric aerosol cloud produced by the eruption of el Chichon in 1982 were made by the Solar Mesosphere Explorer satellite. Measurements of thermal emission at 6.8 microns are inverted to give aerosol extinction coefficients. At this wavelength the extinction coefficient is proportional to the cube of the particle radius, so the measured radiance is proportional to the slant column mass density of aerosols, independent of size distribution. Vertical column mass densities of aerosols and total aerosol mass are found from the 6.8-microns data. The evolution of the aerosol cloud in time and space is discussed. A peak column mass density above 22 km of 0.43 g/sq m occurred near 20 deg N latitude 8 weeks after the eruption. A maximum total global aerosol burden above 22 km of 1.3 x 10(exp 13) g occurred a week later. The aerosol mass determinations are used in conjunction with observations of scattered sunlight from the aerosols at 1.27 and 1.87 microns to derive single-mode log normal columnar size distributions for the aerosol cloud. The results are presented and the time evolution of the particle sizes is discussed.

  15. Characterization of Black Carbon-Containing Aerosol Particles via Soot Particle Aerosol Mass Spectrometry (SP-AMS)

    NASA Astrophysics Data System (ADS)

    Massoli, P.; Fortner, E.; Williams, L. R.; Canagaratna, M.; Trimborn, A.; Jayne, J.; Worsnop, D. R.; Onasch, T. B.

    2012-12-01

    We present measurements of the size-resolved chemical composition of refractory black carbon (rBC) and associated coating species via an ARI soot particle aerosol mass spectrometer (SP AMS). Mass spectral features, size distributions and results from positive matrix factorization (PMF) analyses are presented from several field deployments, spanning a wide array of different rBC sources such traffic-related particulate, biomass burning, urban aerosols with varying degree of aging. For near-roadway conditions, the average size distribution of the traffic related PM is dominated by a rBC mode at ~100 nm in vacuum aerodynamic diameter, Dva (rBC mass fraction ~ 50%) and rBC is mostly associated with hydrocarbon like organic aerosol (HOA). Urban aerosols have a more variable rBC size distributions with Dva varying from ~100 nm (fresh rBC emissions) to ~450 nm (typical of more processed rBC-containing air masses). The coating composition is also observed to vary with aerosol age. For instance, in the air masses sampled offshore the Los Angeles basin during the CalNex 2010 campaign, the relative abundance of OOA (oxygenated organic aerosol) relative to HOA coating increased with the degree of oxygenation of the aerosol. In California, nitrate represented a non-negligible fraction of coating material on rBC particles. Finally, we discuss the properties of biomass burning and long range transport air masses sampled during the 2012 ClearfLo campaign that took place at a rural site southeast of London. All the data presented here are combined with results from the chemical composition information and PMF analyses obtained from co-located HR-ToF aerosol mass spectrometers.

  16. A dual-wavelength single particle aerosol fluorescence monitor

    NASA Astrophysics Data System (ADS)

    Kaye, Paul H.; Stanley, Warren R.; Foot, Virginia; Baxter, Karen; Barrington, Stephen J.

    2005-10-01

    Laser diodes and light-emitting diodes capable of continuous sub-300 nm radiation emission will ultimately represent optimal excitation sources for compact and fieldable bio-aerosol monitors. However, until such devices are routinely available and whilst solid-state UV lasers remain relatively expensive, other low-cost sources of UV can offer advantages. This paper describes one such prototype that employs compact xenon discharge UV sources to excite intrinsic fluorescence from individual particles within an ambient aerosol sample. The prototype monitor samples ambient air via a laminar sheathed-flow arrangement such that particles within the sample flow column are rendered in single file as they intersect the beam from a continuous-wave 660nm diode laser. Each individual particle produces a scattered light signal from which an estimate of particle size (down to ~1 um) may be derived. This same signal also initiates the sequential firing (~10 us apart) of two xenon sources which irradiate the particle with UV pulses centred upon ~280 nm and ~370 nm wavelength, optimal for excitation of bio-fluorophores tryptophan and NADH respectively. For each excitation wavelength, fluorescence is detected across two bands embracing the peak emissions of the same bio-fluorophores. Thus, for each particle, a 2-dimensional fluorescence excitation-emission matrix is recorded together with an estimate of particle size. Current measurement rates are up to ~125 particles/s (limited by the xenon recharge time), corresponding to all particles for concentrations up to ~2 x 104 particles/l. Developments to increase this to ~500 particles/s are in hand. Analysis of results from aerosols of E.coli, BG spores, and a variety of non-biological materials are given.

  17. Studies of Ice Nucleating Aerosol Particles in Arctic Cloud Systems

    NASA Technical Reports Server (NTRS)

    Rogers, David C.; DeMott, Paul J.; Kreidenweis, Sonia M.

    2001-01-01

    The focus of this research is to improve the understanding of ice nucleating aerosol particles (IN) and the role they play in ice formation in Arctic clouds. IN are important for global climate issues in a variety of ways. The primary effect is their role in determining the phase (liquid or solid) of cloud particles. The microscale impact is on cloud particle size, growth rate, shape, fall speed, concentration, radiative properties, and scavenging of gases and aerosols. On a larger scale, ice formation affects the development of precipitation (rate, amount, type, and distribution), latent heat release (rate and altitude), ambient humidity, the persistence of clouds, and cloud albedo. The overall goals of our FIRE 3 research are to characterize the concentrations and variability of Arctic IN during the winter-spring transition, to compare IN measurements with ice concentrations in Arctic clouds, and to examine selected IN samples for particle morphology and chemical there are distinguishable chemical signatures. The results can be combined with other measurements of aerosols, gaseous species, and cloud characteristics in order to understand the processes that determine the phase and concentration of cloud particles.

  18. 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

  19. Dominant Aerosol Particle Type/Mixture Identification at Worldwide Locations Using the Aerosol Robotic Network (AERONET)

    NASA Astrophysics Data System (ADS)

    Giles, D. M.; Holben, B.; Eck, T. F.; Sinyuk, A.; Smirnov, A.; Slutsker, I.; Dickerson, R. R.; Thompson, A. M.; Schafer, J. S.

    2011-12-01

    Aerosol absorption results in atmospheric heating for various forms of particulate matter - we address means of partitioning mineral dust, pollution (e.g., black and brown carbon), and mixtures of the two using remote sensing techniques. Remotely sensed spectral aerosol optical depth (AOD) and single scattering albedo (SSA) derived from Aerosol Robotic Network (AERONET) sun photometer measurements can be used to calculate the absorption aerosol optical depth (AAOD) at 440, 675, and 870 nm. The spectral change in AAOD with wavelength on logarithmic scales provides the absorption Angstrom exponent (AAE). Recently, a few studies have shown that the relationship between aerosol absorption (i.e., AAE or SSA) and aerosol size [i.e., Angstrom exponent (AE) or fine mode fraction (FMF) of the AOD] can estimate the dominant aerosol particle types/mixtures (i.e., dust, pollution, and dust and pollution mixtures) [Bergstrom et al., 2007; Russell et al., 2010; Lee et al. 2010; Giles et al., 2011]. To evaluate these methods, approximately 20 AERONET sites were grouped into various aerosol categories (i.e., dust, mixed, urban/industrial, and biomass burning) based on aerosol types/mixtures identified in previous studies. For data collected between 1999 and 2010, the long-term data set was analyzed to determine the magnitude of spectral AAOD, perform a sensitivity study on AAE by varying the spectral AOD and SSA, and identify dominant aerosol particle types/mixtures. An assessment of the spectral AAOD showed, on average, that the mixed (dust and pollution) category had the highest absorption (AAE ~1.5) followed by biomass burning (AAE~1.3), dust (AAE~1.7), and urban/industrial (AAE~1.2) categories with AAOD (440 nm) varying between 0.03 and 0.09 among these categories. Perturbing input parameters based on the expected uncertainties for AOD (±0.01) and SSA [±0.03; for cases where AOD(440 nm)>0.4], the sensitivity study showed the perturbed AAE mean varied from the unperturbed

  20. Characterization of aerosol particles at the forested site in Lithuania

    NASA Astrophysics Data System (ADS)

    Rimselyte, I.; Garbaras, A.; Kvietkus, K.; Remeikis, V.

    2009-04-01

    Atmospheric particulate matter (PM), especially fine particles (particles with aerodynamic diameter less than 1 m, PM1), has been found to play an important role in global climate change, air quality, and human health. The continuous study of aerosol parameters is therefore imperative for better understanding the environmental effects of the atmospheric particles, as well as their sources, formation and transformation processes. The particle size distribution is particularly important, since this physical parameter determines the mass and number density, lifetime and atmospheric transport, or optical scattering behavior of the particles in the atmosphere (Jaenicke, 1998). Over the years several efforts have been made to improve the knowledge about the chemical composition of atmospheric particles as a function of size (Samara and Voutsa, 2005) and to characterize the relative contribution of different components to the fine particulate matter. It is well established that organic materials constitute a highly variable fraction of the atmospheric aerosol. This fraction is predominantly found in the fine size mode in concentrations ranging from 10 to 70% of the total dry fine particle mass (Middlebrook et al., 1998). Although organic compounds are major components of the fine particles, the composition, formation mechanism of organic aerosols are not well understood. This is because particulate organic matter is part of a complex atmospheric system with hundreds of different compounds, both natural and anthropogenic, covering a wide range of chemical properties. The aim of this study was to characterize the forest PM1, and investigate effects of air mass transport on the aerosol size distribution and chemical composition, estimate and provide insights into the sources and characteristics of carbonaceous aerosols through analysis ^13C/12C isotopic ratio as a function of the aerosol particles size. The measurements were performed at the Rugšteliškis integrated

  1. Ice Nucleation Activity of Various Agricultural Soil Dust Aerosol Particles

    NASA Astrophysics Data System (ADS)

    Schiebel, Thea; Höhler, Kristina; Funk, Roger; Hill, Thomas C. J.; Levin, Ezra J. T.; Nadolny, Jens; Steinke, Isabelle; Suski, Kaitlyn J.; Ullrich, Romy; Wagner, Robert; Weber, Ines; DeMott, Paul J.; Möhler, Ottmar

    2016-04-01

    Recent investigations at the cloud simulation chamber AIDA (Aerosol Interactions and Dynamics in the Atmosphere) suggest that agricultural soil dust has an ice nucleation ability that is enhanced up to a factor of 10 compared to desert dust, especially at temperatures above -26 °C (Steinke et al., in preparation for submission). This enhancement might be caused by the contribution of very ice-active biological particles. In addition, soil dust aerosol particles often contain a considerably higher amount of organic matter compared to desert dust particles. To test agricultural soil dust as a source of ice nucleating particles, especially for ice formation in warm clouds, we conducted a series of laboratory measurements with different soil dust samples to extend the existing AIDA dataset. The AIDA has a volume of 84 m3 and operates under atmospherically relevant conditions over wide ranges of temperature, pressure and humidity. By controlled adiabatic expansions, the ascent of an air parcel in the troposphere can be simulated. As a supplement to the AIDA facility, we use the INKA (Ice Nucleation Instrument of the KArlsruhe Institute of Technology) continuous flow diffusion chamber based on the design by Rogers (1988) to expose the sampled aerosol particles to a continuously increasing saturation ratio by keeping the aerosol temperature constant. For our experiments, soil dust was dry dispersed into the AIDA vessel. First, fast saturation ratio scans at different temperatures were performed with INKA, sampling soil dust aerosol particles directly from the AIDA vessel. Then, we conducted the AIDA expansion experiment starting at a preset temperature. The combination of these two different methods provides a robust data set on the temperature-dependent ice activity of various agriculture soil dust aerosol particles with a special focus on relatively high temperatures. In addition, to extend the data set, we investigated the role of biological and organic matter in more

  2. Stackable differential mobility analyzer for aerosol measurement

    DOEpatents

    Cheng, Meng-Dawn; Chen, Da-Ren

    2007-05-08

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

  3. Measurement of Transport Properties of Aerosolized Nanomaterials

    PubMed Central

    Ku, Bon Ki; Kulkarni, Pramod

    2015-01-01

    Airborne engineered nanomaterials such as single-walled carbon nanotubes (SWCNTs), multi-walled carbon nanotubes (MWCNTs), functionalized MWCNT, graphene, fullerene, silver and gold nanorods were characterized using a tandem system of a differential mobility analyzer and an aerosol particle mass analyzer to obtain their airborne transport properties and understand their relationship to morphological characteristics. These nanomaterials were aerosolized using different generation methods such as electrospray, pneumatic atomization, and dry aerosolization techniques, and their airborne transport properties such as mobility and aerodynamic diameters, mass scaling exponent, dynamic shape factor, and effective density were obtained. Laboratory experiments were conducted to directly measure mobility diameter and mass of the airborne nanomaterials using tandem mobility-mass measurements. Mass scaling exponents, aerodynamic diameters, dynamic shape factors and effective densities of mobility-classified particles were obtained from particle mass and the mobility diameter. Microscopy analysis using Transmission Electron Microscopy (TEM) was performed to obtain morphological descriptors such as envelop diameter, open area, aspect ratio, and projected area diameter. The morphological information from the TEM was compared with measured aerodynamic and mobility diameters of the particles. The results showed that aerodynamic diameter is smaller than mobility diameter below 500 nm by a factor of 2 to 4 for all nanomaterials except silver and gold nanorods. Morphologies of MWCNTs generated by liquid-based method, such as pneumatic atomization, are more compact than those of dry dispersed MWCNTs, indicating that the morphology depends on particle generation method. TEM analysis showed that projected area diameter of MWCNTs appears to be in reasonable agreement with mobility diameter in the size range from 100 – 400 nm. Principal component analysis of the obtained airborne particle

  4. Measurement of Transport Properties of Aerosolized Nanomaterials.

    PubMed

    Ku, Bon Ki; Kulkarni, Pramod

    2015-12-01

    Airborne engineered nanomaterials such as single-walled carbon nanotubes (SWCNTs), multi-walled carbon nanotubes (MWCNTs), functionalized MWCNT, graphene, fullerene, silver and gold nanorods were characterized using a tandem system of a differential mobility analyzer and an aerosol particle mass analyzer to obtain their airborne transport properties and understand their relationship to morphological characteristics. These nanomaterials were aerosolized using different generation methods such as electrospray, pneumatic atomization, and dry aerosolization techniques, and their airborne transport properties such as mobility and aerodynamic diameters, mass scaling exponent, dynamic shape factor, and effective density were obtained. Laboratory experiments were conducted to directly measure mobility diameter and mass of the airborne nanomaterials using tandem mobility-mass measurements. Mass scaling exponents, aerodynamic diameters, dynamic shape factors and effective densities of mobility-classified particles were obtained from particle mass and the mobility diameter. Microscopy analysis using Transmission Electron Microscopy (TEM) was performed to obtain morphological descriptors such as envelop diameter, open area, aspect ratio, and projected area diameter. The morphological information from the TEM was compared with measured aerodynamic and mobility diameters of the particles. The results showed that aerodynamic diameter is smaller than mobility diameter below 500 nm by a factor of 2 to 4 for all nanomaterials except silver and gold nanorods. Morphologies of MWCNTs generated by liquid-based method, such as pneumatic atomization, are more compact than those of dry dispersed MWCNTs, indicating that the morphology depends on particle generation method. TEM analysis showed that projected area diameter of MWCNTs appears to be in reasonable agreement with mobility diameter in the size range from 100 - 400 nm. Principal component analysis of the obtained airborne particle

  5. Global distribution of secondary organic aerosol particle phase state

    NASA Astrophysics Data System (ADS)

    Shiraiwa, M.; Li, Y., Sr.; Tsimpidi, A.; Karydis, V.; Berkemeier, T.; Pandis, S. N.; Lelieveld, J.; Koop, T.; Poeschl, U.

    2016-12-01

    Secondary organic aerosols (SOA) account for a large fraction of submicron particles in the atmosphere and play a key role in aerosol effects on climate, air quality and public health. The formation and aging of SOA proceed through multiple steps of chemical reaction and mass transport in the gas and particle phases, which is challenging for the interpretation of field measurements and laboratory experiments as well as accurate representation of SOA evolution in atmospheric aerosol models. SOA particles can adopt liquid, semi-solid and amorphous solid (glassy) phase states depending on chemical composition, relative humidity and temperature. The particle phase state is crucial for various atmospheric gas-particle interactions, including SOA formation, heterogeneous and multiphase reactions and ice nucleation. We found that organic compounds with a wide variety of functional groups fall into molecular corridors, characterized by a tight inverse correlation between molar mass and volatility. Based on the concept of molecular corridors, we develop a method to estimate glass transition temperatures based on the molar mass and molecular O:C ratio of SOA components, which is a key property for determination of particle phase state. We use the global chemistry climate model EMAC with the organic aerosol module ORACLE to predict the atmospheric SOA phase state. For the planetary boundary layer, global simulations indicate that SOA is mostly liquid in tropical and polar air with high relative humidity, semi-solid in the mid-latitudes, and solid over dry lands. We find that in the middle and upper troposphere (>500 hPa) SOA should be mostly in a glassy solid phase state. Thus, slow diffusion of water, oxidants, and organic molecules could kinetically limit gas-particle interactions of SOA in the free and upper troposphere, promote ice nucleation and facilitate long-range transport of reactive and toxic organic pollutants embedded within SOA.

  6. The Impact of Aerosol Particle Mixing State on the Hygroscopicity of Sea Spray Aerosol.

    PubMed

    Schill, Steven R; Collins, Douglas B; Lee, Christopher; Morris, Holly S; Novak, Gordon A; Prather, Kimberly A; Quinn, Patricia K; Sultana, Camille M; Tivanski, Alexei V; Zimmermann, Kathryn; Cappa, Christopher D; Bertram, Timothy H

    2015-06-24

    Aerosol particles influence global climate by determining cloud droplet number concentrations, brightness, and lifetime. Primary aerosol particles, such as those produced from breaking waves in the ocean, display large particle-particle variability in chemical composition, morphology, and physical phase state, all of which affect the ability of individual particles to accommodate water and grow into cloud droplets. Despite such diversity in molecular composition, there is a paucity of methods available to assess how particle-particle variability in chemistry translates to corresponding differences in aerosol hygroscopicity. Here, an approach has been developed that allows for characterization of the distribution of aerosol hygroscopicity within a chemically complex population of atmospheric particles. This methodology, when applied to the interpretation of nascent sea spray aerosol, provides a quantitative framework for connecting results obtained using molecular mimics generated in the laboratory with chemically complex ambient aerosol. We show that nascent sea spray aerosol, generated in situ in the Atlantic Ocean, displays a broad distribution of particle hygroscopicities, indicative of a correspondingly broad distribution of particle chemical compositions. Molecular mimics of sea spray aerosol organic material were used in the laboratory to assess the volume fractions and molecular functionality required to suppress sea spray aerosol hygroscopicity to the extent indicated by field observations. We show that proper accounting for the distribution and diversity in particle hygroscopicity and composition are important to the assessment of particle impacts on clouds and global climate.

  7. Methods of analyzing composition of aerosol particles

    DOEpatents

    Reilly, Peter T.A.

    2013-02-12

    An aerosol particle analyzer includes a laser ablation chamber, a gas-filled conduit, and a mass spectrometer. The laser ablation chamber can be operated at a low pressure, which can be from 0.1 mTorr to 30 mTorr. The ablated ions are transferred into a gas-filled conduit. The gas-filled conduit reduces the electrical charge and the speed of ablated ions as they collide and mix with buffer gases in the gas-filled conduit. Preferably, the gas filled-conduit includes an electromagnetic multipole structure that collimates the nascent ions into a beam, which is guided into the mass spectrometer. Because the gas-filled conduit allows storage of vast quantities of the ions from the ablated particles, the ions from a single ablated particle can be analyzed multiple times and by a variety of techniques to supply statistically meaningful analysis of composition and isotope ratios.

  8. Chemical evolution of multicomponent aerosol particles during evaporation

    NASA Astrophysics Data System (ADS)

    Zardini, Alessandro; Riipinen, Ilona; Pagels, Joakim; Eriksson, Axel; Worsnop, Douglas; Switieckli, Erik; Kulmala, Markku; Bilde, Merete

    2010-05-01

    Atmospheric aerosol particles have an important but not well quantified effect on climate and human health. Despite the efforts made in the last decades, the formation and evolution of aerosol particles in the atmosphere is still not fully understood. The uncertainty is partly due to the complex chemical composition of the particles which comprise inorganic and organic compounds. Many organics (like dicarboxylic acids) can be present both in the gas and in the condensed phase due to their low vapor pressure. Clearly, an understanding of this partition is crucial to address any other issue in atmospheric physics and chemistry. Moreover, many organics are water soluble, and their influence on the properties of aqueous solution droplets is still poorly characterized. The solid and sub-cooled liquid state vapor pressures of some organic compounds have been previously determined by measuring the evaporation rate of single-compound crystals [1-3] or binary aqueous droplets [4-6]. In this work, we deploy the HTDMA technique (Hygroscopicity Tandem Differential Mobility Analyzer) coupled with a 3.5m laminar flow-tube and an Aerosol Mass Spectrometer (AMS) for determining the chemical evolution during evaporation of ternary droplets made of one dicarboxylic acid (succinic acid, commonly found in atmospheric samples) and one inorganic compound (sodium chloride or ammonium sulfate) in different mixing ratios, in equilibrium with water vapor at a fixed relative humidity. In addition, we investigate the evaporation of multicomponent droplets and crystals made of three organic species (dicarboxylic acids and sugars), of which one or two are semi-volatile. 1. Bilde M. and Pandis, S.N.: Evaporation Rates and Vapor Pressures of Individual Aerosol Species Formed in the Atmospheric Oxidation of alpha- and beta-Pinene. Environmental Science and Technology, 35, 2001. 2. Bilde M., et al.: Even-Odd Alternation of Evaporation Rates and Vapor Pressures of C3-C9 Dicarboxylic Acid Aerosols

  9. Aerosol optical properties measurement by recently developed cavity-enhanced aerosol single scattering albedometer

    NASA Astrophysics Data System (ADS)

    Zhao, Weixiong; Xu, Xuezhe; Zhang, Qilei; Fang, Bo; Qian, Xiaodong; Chen, Weidong; Gao, Xiaoming; Zhang, Weijun

    2015-04-01

    Development of appropriate and well-adapted measurement technologies for real-time in-situ measurement of aerosol optical properties is an important step towards a more accurate and quantitative understanding of aerosol impacts on climate and the environment. Aerosol single scattering albedo (SSA, ω), the ratio between the scattering (αscat) and extinction (αext) coefficients, is an important optical parameter that governs the relative strength of the aerosol scattering and absorption capacity. Since the aerosol extinction coefficient is the sum of the absorption and scattering coefficients, a commonly used method for the determination of SSA is to separately measure two of the three optical parameters - absorption, scattering and extinction coefficients - with different instruments. However, as this method involves still different instruments for separate measurements of extinction and absorption coefficients under different sampling conditions, it might cause potential errors in the determination of SSA value, because aerosol optical properties are very sensitive to the sampling conditions such as temperature and relative humidity (RH). In this paper, we report on the development of a cavity-enhanced aerosol single scattering albedometer incorporating incoherent broad-band cavity-enhanced spectroscopy (IBBCEAS) and an integrating sphere (IS) for direct in-situ measurement of aerosol scattering and extinction coefficients on the exact same sample volume. The cavity-enhanced albedometer holds great promise for high-sensitivity and high-precision measurement of ambient aerosol scattering and extinction coefficients (hence absorption coefficient and SSA determination) and for absorbing trace gas concentration. In addition, simultaneous measurements of aerosol scattering and extinction coefficients enable a potential application for the retrieval of particle number size distribution and for faster retrieval of aerosols' complex RI. The albedometer was deployed to

  10. Chamber LIDAR measurements of aerosolized biological simulants

    NASA Astrophysics Data System (ADS)

    Brown, David M.; Thrush, Evan P.; Thomas, Michael E.; Siegrist, Karen M.; Baldwin, Kevin; Quizon, Jason; Carter, Christopher C.

    2009-05-01

    A chamber aerosol LIDAR is being developed to perform well-controlled tests of optical scattering characteristics of biological aerosols, including Bacillus atrophaeus (BG) and Bacillus thuringiensis (BT), for validation of optical scattering models. The 1.064 μm, sub-nanosecond pulse LIDAR allows sub-meter measurement resolution of particle depolarization ratio or backscattering cross-section at a 1 kHz repetition rate. Automated data acquisition provides the capability for real-time analysis or recording. Tests administered within the refereed 1 cubic meter chamber can provide high quality near-field backscatter measurements devoid of interference from entrance and exit window reflections. Initial chamber measurements of BG depolarization ratio are presented.

  11. The Impact of Aerosol Particle Mixing State on the Hygroscopicity of Sea Spray Aerosol

    PubMed Central

    2015-01-01

    Aerosol particles influence global climate by determining cloud droplet number concentrations, brightness, and lifetime. Primary aerosol particles, such as those produced from breaking waves in the ocean, display large particle–particle variability in chemical composition, morphology, and physical phase state, all of which affect the ability of individual particles to accommodate water and grow into cloud droplets. Despite such diversity in molecular composition, there is a paucity of methods available to assess how particle–particle variability in chemistry translates to corresponding differences in aerosol hygroscopicity. Here, an approach has been developed that allows for characterization of the distribution of aerosol hygroscopicity within a chemically complex population of atmospheric particles. This methodology, when applied to the interpretation of nascent sea spray aerosol, provides a quantitative framework for connecting results obtained using molecular mimics generated in the laboratory with chemically complex ambient aerosol. We show that nascent sea spray aerosol, generated in situ in the Atlantic Ocean, displays a broad distribution of particle hygroscopicities, indicative of a correspondingly broad distribution of particle chemical compositions. Molecular mimics of sea spray aerosol organic material were used in the laboratory to assess the volume fractions and molecular functionality required to suppress sea spray aerosol hygroscopicity to the extent indicated by field observations. We show that proper accounting for the distribution and diversity in particle hygroscopicity and composition are important to the assessment of particle impacts on clouds and global climate. PMID:27162963

  12. Aerosol generation and measurement of multi-wall carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Myojo, Toshihiko; Oyabu, Takako; Nishi, Kenichiro; Kadoya, Chikara; Tanaka, Isamu; Ono-Ogasawara, Mariko; Sakae, Hirokazu; Shirai, Tadashi

    2009-01-01

    Mass production of some kinds of carbon nanotubes (CNT) is now imminent, but little is known about the risk associated with their exposure. It is important to assess the propensity of the CNT to release particles into air for its risk assessment. In this study, we conducted aerosolization of a multi-walled CNT (MWCNT) to assess several aerosol measuring instruments. A Palas RBG-1000 aerosol generator applied mechanical stress to the MWCNT by a rotating brush at feed rates ranging from 2 to 20 mm/h, which the MWCNT was fed to a two-component fluidized bed. The fluidized bed aerosol generator was used to disperse the MWCNT aerosol once more. We monitored the generated MWCNT aerosol concentrations based on number, area, and mass using a condensation particle counter and nanoparticle surface area monitor. Also we quantified carbon mass in MWCNT aerosol samples by a carbon monitor. The shape of aerosolized MWCNT fibers was observed by a scanning electron microscope (SEM). The MWCNT was well dispersed by our system. We found isolated MWCNT fibers in the aerosols by SEM and the count median lengths of MWCNT fibers were 4-6 μm. The MWCNT was quantified by the carbon monitor with a modified condition based on the NIOSH analytical manual. The MWCNT aerosol concentration (EC mass base) was 4 mg/m3 at 2 mm/h in this study.

  13. In situ measurements of organics, meteoritic material, mercury, and other elements in aerosols at 5 to 19 kilometers

    PubMed

    Murphy; Thomson; Mahoney

    1998-11-27

    In situ measurements of the chemical composition of individual aerosol particles at altitudes between 5 and 19 kilometers reveal that upper tropospheric aerosols often contained more organic material than sulfate. Although stratospheric aerosols primarily consisted of sulfuric acid and water, many also contained meteoritic material. Just above the tropopause, small amounts of mercury were found in over half of the aerosol particles that were analyzed. Overall, there was tremendous variety in aerosol composition. One measure of this diversity is that at least 45 elements were detected in aerosol particles. These results have wide implications for the complexity of aerosol sources and chemistry. They also offer possibilities for understanding the transport of atmospheric aerosols.

  14. On-line derivatization for hourly measurements of gas- and particle-phase Semi-Volatile oxygenated organic compounds by Thermal desorption Aerosol Gas chromatography (SV-TAG)

    NASA Astrophysics Data System (ADS)

    Isaacman, G.; Kreisberg, N. M.; Yee, L. D.; Worton, D. R.; Chan, A. W. H.; Moss, J. A.; Hering, S. V.; Goldstein, A. H.

    2014-07-01

    Laboratory oxidation studies have identified a large number of oxygenated organic compounds that can be used as tracers to understand sources and oxidation chemistry of atmospheric particulate matter. Quantification of these compounds in ambient environments has traditionally relied on low time-resolution collection of filter samples followed by offline sample treatment with a derivatizing agent to allow analysis by gas chromatography of otherwise non-elutable organic chemicals with hydroxyl groups. We present here an automated in situ instrument for the measurement of highly polar organic semi-volatile and low-volatility compounds in both the gas- and particle-phase with hourly time-resolution. The dual-cell Semi-Volatile Thermal desorption Aerosol Gas chromatograph (SV-TAG) with derivatization collects particle-only and combined particle-plus-vapor samples on two parallel sampling cells that are analyzed in series by thermal desorption into helium saturated with derivatizing agent. Introduction of MSTFA, a silylating agent, yields complete derivatization of all tested compounds, including alkanoic acids, polyols, diacids, sugars, and multifunctional compounds. In laboratory tests, derivatization is found to be highly reproducible (< 3% variability). During field deployment, a regularly injected internal standard is used to correct for variability in detector response, derivatization efficiency, desorption efficiency, and transfer efficiency. Error in quantification from instrument fluctuations is found to be less than 10% for hydrocarbons and less than 15% for all oxygenates for which a functionally similar internal standard is available. After internal standard corrections, calibration curves are found to be linear for all compounds over the span of one month with comparable response on both of the parallel sampling cells.

  15. Morphology and Optical Properties of Mixed Aerosol Particles

    NASA Astrophysics Data System (ADS)

    Fard, Mehrnoush M.; Krieger, Ulrich; Rudich, Yinon; Marcolli, Claudia; Peter, Thomas

    2015-04-01

    Experiments and modeling studies have shown that deliquesced aerosols can be present not only as one-phase system containing organics, inorganic salts and water, but often as two-phase systems consisting of a predominantly organic and a predominantly inorganic aqueous phase 1,2. Recent laboratory studies conducted with model mixtures representing tropospheric aerosols1,2,3, secondary organic aerosol (SOA) from smog chamber experiments4, and field measurements5 suggest that liquid- liquid phase separations (LLPS) is indeed a common phenomenon in mixed organic/ ammonium sulfate (AS) particles. During LLPS, particles may adopt different morphologies mainly core- shell and partially engulfed. A core- shell configuration will have consequences for heterogeneous chemistry and hygroscopicity and as a result will alter the optical properties of the particles since the aqueous inorganic-rich phase will be totally enclosed by a probably highly viscous organic coating with low diffusivity for reactants and water. The primary objective of this project is to establish a method for investigating the morphology of mixed inorganic and absorbing organic compounds of atmospheric relevance and study their radiative properties before, during, and after phase transitions mainly during LLPS. This will be the first study looking into the radiative effect of LLPS in detail. In this first experiment, the behavior of single droplets of carminic acid (CA)/ AS/ H2O mixture was monitored during relative humidity (RH) cycles using optical microscopy. The same mixture particle was levitated in an electrodynamic balance (EDB) and the change in its absorption properties was measured at varying RH. We also intend to determine the occurrence of LLPS in accumulation- sized particles and the change in their absorption using a cavity ring down aerosol spectrometer. If LLPS alters the absorptive properties of the suggested model aerosols significantly, absorption measurements of accumulation mode

  16. Aerosol Absorption Measurements in MILAGRO.

    NASA Astrophysics Data System (ADS)

    Gaffney, J. S.; Marley, N. A.; Arnott, W. P.; Paredes-Miranda, L.; Barnard, J. C.

    2007-12-01

    During the month of March 2006, a number of instruments were used to determine the absorption characteristics of aerosols found in the Mexico City Megacity and nearby Valley of Mexico. These measurements were taken as part of the Department of Energy's Megacity Aerosol Experiment - Mexico City (MAX-Mex) that was carried out in collaboration with the Megacity Interactions: Local and Global Research Observations (MILAGRO) campaign. MILAGRO was a joint effort between the DOE, NSF, NASA, and Mexican agencies aimed at understanding the impacts of a megacity on the urban and regional scale. A super-site was operated at the Instituto Mexicano de Petroleo in Mexico City (designated T-0) and at the Universidad Technologica de Tecamac (designated T-1) that was located about 35 km to the north east of the T-0 site in the State of Mexico. A third site was located at a private rancho in the State of Hidalgo approximately another 35 km to the northeast (designated T-2). Aerosol absorption measurements were taken in real time using a number of instruments at the T-0 and T-1 sites. These included a seven wavelength aethalometer, a multi-angle absorption photometer (MAAP), and a photo-acoustic spectrometer. Aerosol absorption was also derived from spectral radiometers including a multi-filter rotating band spectral radiometer (MFRSR). The results clearly indicate that there is significant aerosol absorption by the aerosols in the Mexico City megacity region. The absorption can lead to single scattering albedo reduction leading to values below 0.5 under some circumstances. The absorption is also found to deviate from that expected for a "well-behaved" soot anticipated from diesel engine emissions, i.e. from a simple 1/lambda wavelength dependence for absorption. Indeed, enhanced absorption is seen in the region of 300-450 nm in many cases, particularly in the afternoon periods indicating that secondary organic aerosols are contributing to the aerosol absorption. This is likely due

  17. Statistical characteristics of atmospheric aerosol as determined from AERONET measurements

    NASA Astrophysics Data System (ADS)

    Yoon, Jongmin; Kokhanovsky, Alexander

    2015-04-01

    Seasonal means and standard deviations of column-integrated aerosol optical properties (e.g. spectral aerosol optical thickness (AOT), single scattering albedo, phase function, Ångström exponent, volume particle size distribution, complex refractive index, absorbing aerosol optical thickness) from several Aerosol Robotic Network (AERONET) sites located in typical aerosol source and background regions are investigated (Holben et al., 1998). The AERONET program is an inclusive network of ground-based sun-photometers that measure atmospheric aerosol optical properties (http://aeronet.gsfc.nasa.gov/). The results can be used for improving the accuracy of satellite-retrieved AOT, assessments of the global aerosol models, studies of atmospheric pollution and aerosol radiative forcing on climate. We have paid a special attention to several AERONET sites that are Mexico_City (Mexico), Alta_Floresta (Brazil), Avignon (France), Solar_Village (Saudi Arabia), and Midway_Island (Pacific) representative for industrial/urban, biomass burning, rural, desert dust and oceanic aerosols, respectively. We have found that the optical and microphysical aerosol properties are highly dependent on the local aerosol emission sources and seasonal meteorological conditions.

  18. Glyoxal and Methylglyoxal in Atlantic Seawater and marine Aerosol Particles

    NASA Astrophysics Data System (ADS)

    van Pinxteren, Manuela; Herrmann, Hartmut

    2014-05-01

    The two α-dicarbonyls glyoxal (CHOCHO; GLY) and methylglyoxal (CH3COCHO; MGLY) have attracted increasing attention over the past years because of their potential role in secondary organic aerosol formation. Recently Sinreich et al. (2010) suggested the open ocean as an important (so far unknown) source for GLY in the atmosphere. To date, there are few available field data of these compounds in the marine area. In this study we present measurements of GLY and MGLY in seawater and marine aerosol particles sampled during a transatlantic Polarstern cruise in spring 2011. In seawater we especially investigated the sea surface microlayer (sampled with the glass plate technique) as it is the direct interface between ocean and atmosphere. Analytical measurements were based on derivatisation with o-(2,3,4,5,6-Pentafluorobenzyl)-hydroxylamine reagent, solvent extraction and GC-MS (SIM) analysis. The results show that GLY and MGLY are present in the sea surface microlayer of the ocean and corresponding bulkwater with average concentrations of 228 ng L-1 (GLY) and 196 ng L-1 (MGLY). Significant enrichment (factor of 4) of GLY and MGLY in the sea surface microlayer was found implying photochemical production of the two carbonyls though a clear connection to global radiation was not observed. On aerosol particles, both carbonyls were detected (average concentration 0.2 ng m-3) and are strongly connected to each other, suggesting similar formation mechanisms. Both carbonyls show a very good correlation with particulate oxalate, supporting the idea of a secondary formation of oxalic acid via GLY and MGLY. A slight correlation of the two carbonyls in the sea surface microlayer and in the aerosol particles was found at co-located sampling areas. In summary, the results of GLY and MGLY in marine aerosol particles and in the oceanic water give first insights towards interaction processes of these alpha dicarbonyls between ocean and atmosphere (van Pinxteren and Herrmann (2013

  19. Composition and Particle Size Retrievals for Homogeneous Binary Aerosols

    NASA Astrophysics Data System (ADS)

    Niedziela, R. F.; Argon, P.; Bejcek, L.

    2014-12-01

    Tropospheric aerosols have widely varying compositions, shapes, and sizes. The ability to measure these physical characteristics, coupled with knowledge about their optical properties, can provide insight as to how these particles might participate in atmospheric processes, including their interaction with light. Over the past several years, our laboratory has been involved in developing methods to determine basic physical properties of laboratory-generated particles based on the analysis of infrared extinction spectra of multi-component aerosols. Here we report the results of a complete study on the applicability of well-known refractive index mixing rules to homogeneous binary liquid organic aerosols in an effort to yield in situ measurements of particle size and composition. In particular, we present results for terpenoid (carvone/nopinone) and long-chain hydrocarbon (squalane/squalene) mixtures. The included image shows model carvone/nopinone extinction spectra that were computed using the Lorentz-Lorenz mixing rule on complex refractive index data for the pure components.

  20. Measurement of relative humidity dependent light scattering of aerosols

    NASA Astrophysics Data System (ADS)

    Fierz-Schmidhauser, R.; Zieger, P.; Wehrle, G.; Jefferson, A.; Ogren, J. A.; Baltensperger, U.; Weingartner, E.

    2009-09-01

    Relative humidity (RH) influences the water content of aerosol particles and therefore has an important impact on the particles' ability to scatter visible light. The RH dependence of the particle light scattering coefficient (σsp) is therefore an important measure for climate forcing calculations. We built a humidification system for a nephelometer which allows the measurement of σsp at a defined RH in the range of 40-90%. This RH conditioner consists of a humidifier followed by a dryer, which enables us to measure the hysteresis behavior of deliquescent aerosol particles. In this paper we present the set-up of a new humidified nephelometer, a detailed characterization with well defined laboratory generated aerosols, and a first application in the field by comparing our instrument to another humidified nephelometer. Monodisperse ammonium sulfate and sodium chloride particles were measured at four different dry particle sizes. Agreement between measurement and prediction based on Mie theory was found for both σsp and f(RH)=σsp(RH)/σsp(dry) within the range of uncertainty. The two humidified nephelometers measuring at a rural site in the Black Forest (Germany) often detected different f(RH), probably caused by the aerosol hysteresis behavior: when the aerosol was metastable, therefore was scattering more light, only one instrument detected the higher f(RH).

  1. Measurement of relative humidity dependent light scattering of aerosols

    NASA Astrophysics Data System (ADS)

    Fierz-Schmidhauser, R.; Zieger, P.; Wehrle, G.; Jefferson, A.; Ogren, J. A.; Baltensperger, U.; Weingartner, E.

    2010-01-01

    Relative humidity (RH) influences the water content of aerosol particles and therefore has an important impact on the particles' ability to scatter visible light. The RH dependence of the particle light scattering coefficient (σsp is therefore an important measure for climate forcing calculations. We built a humidification system for a nephelometer which allows the measurement of σsp at a defined RH in the range of 40-90%. This RH conditioner consists of a humidifier followed by a dryer, which enables us to measure the hysteresis behavior of deliquescent aerosol particles. In this paper we present the set-up of a new humidified nephelometer, a detailed characterization with well defined laboratory generated aerosols, and a first application in the field by comparing our instrument to another humidified nephelometer. Monodisperse ammonium sulfate and sodium chloride particles were measured at four different dry particle sizes. Agreement between measurement and prediction based on Mie theory was found for both σsp and f(RH)=σsp(RH)/σsp(dry) within the range of uncertainty. The two humidified nephelometers measuring at a rural site in the Black Forest (Germany) often detected different f(RH), probably caused by the aerosol hysteresis behavior: when the aerosol was metastable, therefore was scattering more light, only one instrument detected the higher f(RH).

  2. Tracking Water Diffusion Fronts in a Highly Viscous Aerosol Particle

    NASA Astrophysics Data System (ADS)

    Bastelberger, Sandra; Krieger, Ulrich; Peter, Thomas

    2016-04-01

    Field measurements indicate that atmospheric secondary aerosol particles can be present in a highly viscous, glassy state [1]. In contrast to liquid state particles, the gas phase equilibration is kinetically limited and governed by condensed phase diffusion. In recent water diffusion experiments on highly viscous single aerosol particles levitated in an electrodynamic balance (EDB) we observed a characteristic shift behavior of the Mie whispering gallery modes (WGM) indicative of the changing radial structure of the particle, thus providing us with an experimental method to track the diffusion process inside the particle. When a highly viscous, homogeneous particle is exposed to an abrupt increase in relative humidity, the rapid gas phase diffusion and strong concentration dependence of the diffusion coefficient in the condensed phase lead to extremely steep water concentration gradients inside the particle, reminiscent of diffusion fronts. The resulting quasi step-like concentration profile motivates the introduction of a simple core-shell model describing the morphology of the non-equilibrium particle during humidification. The subsequent particle growth and reduction of the shell refractive index can be observed as red and blueshift behavior of the WGM, respectively. The shift pattern can be attributed to a core-shell radius ratio and particle radius derived from model calculations [2]. If supplemented with growth information obtained from the WGM redshift and thermodynamic equilibrium data, we can infer a comprehensive picture of the time evolution of the diffusion fronts in the framework of our core-shell model. The measured time dependent concentration profile is then compared with simulations solving the non-linear diffusion equation [3] [1] Virtanen, A., et al., Nature, 467, 824-827, 2010 [2] Kaiser, T., Schweiger, G., Computers in Physics, Vol. 7, No. 6, 682-686, Nov/Dec 1993 [3] Zobrist, B., Soonsin, V., Luo, B.P., Peter, T. et al., Phys. Chem. Chem

  3. Long term aerosol and trace gas measurements in Central Amazonia

    NASA Astrophysics Data System (ADS)

    Artaxo, Paulo; Barbosa, Henrique M. J.; Ferreira de Brito, Joel; Carbone, Samara; Rizzo, Luciana V.; Andreae, Meinrat O.; Martin, Scot T.

    2016-04-01

    The central region of the Amazonian forest is a pristine region in terms of aerosol and trace gases concentrations. In the wet season, Amazonia is actually one of the cleanest continental region we can observe on Earth. A long term observational program started 20 years ago, and show important features of this pristine region. Several sites were used, between then ATTO (Amazon Tall Tower Observatory) and ZF2 ecological research site, both 70-150 Km North of Manaus, receiving air masses that traveled over 1500 km of pristine tropical forests. The sites are GAW regional monitoring stations. Aerosol chemical composition (OC/EC and trace elements) is being analysed using filters for fine (PM2.5) and coarse mode aerosol as well as Aerodyne ACSM (Aerosol Chemical Speciation Monitors). VOCs are measured using PTR-MS, while CO, O3 and CO2 are routinely measured. Aerosol absorption is being studied with AE33 aethalometers and MAAP (Multi Angle Absorption Photometers). Aerosol light scattering are being measured at several wavelengths using TSI and Ecotech nephelometers. Aerosol size distribution is determined using scanning mobility particle sizer at each site. Lidars measure the aerosol column up to 12 Km providing the vertical profile of aerosol extinction. The aerosol column is measures using AERONET sun photometers. In the wet season, organic aerosol comprises 75-85% of fine aerosol, and sulfate and nitrate concentrations are very low (1-3 percent). Aerosols are dominated by biogenic primary particles as well as SOA from biogenic precursors. Black carbon in the wet season accounts for 5-9% of fine mode aerosol. Ozone in the wet season peaks at 10-12 ppb at the middle of the day, while carbon monoxide averages at 50-80 ppb. Aerosol optical thickness (AOT) is a low 0.05 to 0.1 at 550 nm in the wet season. Sahara dust transport events sporadically enhance the concentration of soil dust aerosols and black carbon. In the dry season (August-December), long range transported

  4. Aerosol Particle Property Comparisons Between MISR and AERONET Retrieved Values

    NASA Astrophysics Data System (ADS)

    Gaitley, B. J.; Kahn, R. A.

    2005-12-01

    Aerosol optical depth (AOT) data from the Multi-angle ImagingSpectroRadiometer (MISR) instrument aboard the NASA Earth Observing System's Terra satellite have already been systematically compared with ground-based data from the AERONET network. As a result of that study, MISR data are now being reprocessed with improved aerosol algorithms and aerosol models. The follow-on study reported here systematically compares MISR and AERONET particle micro-physical properties. This project is currently underway. Our goal is to use the statistical power of numerous AERONET measurements to map the behavior of the MISR property retrievals, identify strength and surprises in the MISR data, and use this information both to refine further the MISR retrieval algorithms and to assess the likely error envelopes in the MISR products. Multi-year data from 36 carefully chosen sites having good long-term measurement records are stratified by broad classes of aerosol air mass types: maritime, biomass burning, desert dust, pollution, and continental aerosols. Available AERONET spectral AOT measurements for two-hour windows around MISR overpass times are interpolated to MISR wavelengths and averaged, and AOT variability over the two-hour window is noted. Sky-scan AERONET data, taken only once an hour, are also were interpolated to MISR wavelengths, and are averaged over a four-hour window provided the variability is smaller than MISR sensitivity to particle properties based on previous work. MISR retrievals over the 17.6 km standard retrieval regions that include the AERONET sites are preferentially used for the comparison. The MISR measurements are averages of over all "successful" aerosol type models in the MISR algorithm climatology, where success is measured by the degree to which multi-angle, multi-spectral top-of-atmosphere radiances match modeled radiances, using several chi-squared tests. Angstrom exponent, single scattering albedo, and size distribution mean values and variance

  5. Single Particle Characterization of Free Tropospheric Aerosols at the Pico Mountain Observatory over the North Atlantic

    NASA Astrophysics Data System (ADS)

    Mazzoleni, C.; China, S.; Scarnato, B. V.; Moffet, R.; OBrien, R. E.; Gilles, M. K.; Fialho, P. J.; Ampadu, M.; Kumar, S.; Dzepina, K.; Wright, K.; Sharma, N.; Zhang, B.; Owen, R. C.; Perlinger, J. A.; Jacques, H.; Helmig, D.; Dziobak, M.; Kramer, L. J.; Mazzoleni, L. R.

    2014-12-01

    Free tropospheric aerosols are being studied at the Pico Mountain Observatory, located near the top of the Pico volcano in the Azores, Portugal (38.47°N, 28.40°W, 2225m asl). Typically above the marine boundary layer in the summer, this is an ideal site to study aerosol transported over long distances across the Atlantic Ocean. Aerosols reaching the Observatory often originate from North America and sometimes from Africa and Europe. Aerosols instrumentation deployed at the site include: a) an optical particle counter, b) a 7-wavelength aethalometer to measure black carbon equivalent mass concentration, c) a 3-wavelength nephelometer to measure total and backward light scattering, d) four high volume samplers for aerosol chemical characterization, and e) a sequential aerosol sampler and a 4-stage impactor to collect particles on different substrates for microscopy analysis. The origin and transport pathways of the air masses sampled at the site are determined using FLEXible PARTicle (FLEXPART) dispersion modeling retroplume analysis. Single particle morphology and mixing states were determined using electron microscopy, energy dispersive X-ray spectroscopy, and scanning transmission x-ray microscopy. This study provides an overview of different types of aerosol collected at Pico Mountain Observatory. We investigated morphology and mixing of various types of particles, including dust, soot, salt and organic particles transported to the Observatory. Soot particles were often mixed/coated with other material and exhibited very compact shape. Dust particles were often mixed with sulfur containing species. We also observed dust particles that were mixed with coated soot particles. During some events, we observed soot and sulfate aerosol trapped within organic matter. The results of this study have implications on how aerosol particles and their internal mixing can be represented in numerical models for remote regions of the free troposphere.

  6. 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).

  7. 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).

  8. 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

  9. Crowdsourced aerosol measurements using smartphone spectropolarimeters

    NASA Astrophysics Data System (ADS)

    Rietjens, J.; Snik, F.; Keller, C. U.; Heinsbroek, R.; van Harten, G.; Heikamp, S.; de Boer, J.; Zeegers, E.; Einarsen, L.; Hasekamp, O.; Smit, M.; di Noia, A.; Apituley, A.; Mijling, B.; Hendriks, E.; Stammes, P.; Volten, H.; Vonk, J.; Berkhout, S.; Haaima, M.; van der Hoff, R.; Stam, D.; Navarro, R.; Bettonvil, F.

    2013-12-01

    We present the development, organisation and results of a large citizen science project with the goal to measure and characterise atmospheric aerosols using a network of smartphone spectropolarimeters. The project, called ';iSPEX', was conceived and carried out in the Netherlands, and organised the first National iSPEX measurement day on July 8th 2013. During this day, more than 3000 people performed over 6000 measurements with their own smartphones using a special add-on and a dedicated app. These measurements were sent to a central database, processed and analysed using a vector-radiative transfer based inversion code in order to extract aerosol properties. The add-on that transforms the camera of the smartphone into a spectropolarimeter and thereby the smartphone into a scientific instrument, employs the method of spectral modulation [1]. The add-on is comprised of polymer parts and was mass-produced and distributed to almost 10000 people. A single measurement involves scanning the blue sky, thereby yielding the angular behaviour of the degree of linear polarisation as a function of wavelength. Although a single iSPEX measurement is not accurate enough, combining many measurements of a crowdsourced experiment with thousands of people should yield sufficiently accurate results that may be interpreted in terms of aerosol optical thickness and aerosol particle properties. By analysing not only the measured results, but also the motivation of the general public to participate, we learn about the possibilities to create a new kind of air quality measurement network. At the conference, we will demonstrate iSPEX and present the results of the first measurement day. We hope to convince you that iSPEX is not only a great outreach tool to engage the public in issues pertaining to atmospheric aerosols, but that it may also contribute to the solution of several urgent societal and scientific problems. [1] Snik, F., Karalidi, T., Keller, C.U.. Spectral modulation for full

  10. METHODS OF CALCULATINAG LUNG DELIVERY AND DEPOSITION OF AEROSOL PARTICLES

    EPA Science Inventory


    Lung deposition of aerosol is measured by a variety of methods. Total lung deposition can be measured by monitoring inhaled and exhaled aerosols in situ by laser photometry or by collecting the aerosols on filters. The measurements can be performed accurately for stable monod...

  11. METHODS OF CALCULATINAG LUNG DELIVERY AND DEPOSITION OF AEROSOL PARTICLES

    EPA Science Inventory


    Lung deposition of aerosol is measured by a variety of methods. Total lung deposition can be measured by monitoring inhaled and exhaled aerosols in situ by laser photometry or by collecting the aerosols on filters. The measurements can be performed accurately for stable monod...

  12. Radial inhomogeneities in particle composition of single, levitated aerosol particles observed by Mie resonance spectroscopy (Invited)

    NASA Astrophysics Data System (ADS)

    Krieger, U. K.; Steimer, S.; Lienhard, D.; Bastelberger, S.

    2013-12-01

    Recent observations have indicated that organic aerosol particles in the atmosphere may exist in an amorphous semi-solid or even solid (i.e. glassy) state, e.g. [1]. The influence of highly viscous and glassy states on the timescale of aerosol particle equilibration with respect to water vapor have been investigated for some model systems of atmospheric aerosol, e.g. [2,3]. In particular, it has been shown that the kinetics of the water absorption/desorption process is controlled entirely by liquid-phase diffusion of water molecules for a highly viscous aerosol particle. A liquid phase diffusion model based on numerically solving the non-linear diffusion equation predicts strong internal gradients in water concentration when condensed phase diffusion impedes the water uptake from the gas phase [2]. Here we observe and quantify the internal concentration gradients in single, levitated, micron size aerosol particles of aqueous MBTCA (3-methyl-1,2,3-Butanetricarboxylic acid) and shikimic acid using elastic Mie resonance spectroscopy. A single, aqueous particle is levitated in an electro-dynamic balance (for details see [2]), dried for several days at room temperature, cooled to the target temperature and exposed to a rapid change in relative humidity. In addition to measuring the elastically backscattered light of a 'white light ' LED source and recording the full spectrum with a spectrograph as in [2], we use a tunable diode laser (TDL) to scan high resolution TE- and TM spectra. This combination allows observing various Mie resonance mode orders simultaneously. Since we perform the experiment at low temperatures and low humidities the changes in the Mie-spectra due to water uptake are sufficiently slow to resolve the kinetics. Experimental Mie resonance spectra are inverted to concentration profiles of water within the particle by applying the numerical diffusion model [2] in conjunction with Mie calculations of multilayered spheres [4]. Potential implications for

  13. 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.

  14. Influence of crustal dust and sea spray supermicron particle concentrations and acidity on inorganic NO3− aerosol during the 2013 Southern Oxidant and Aerosol Study

    DOE PAGES

    Allen, H. M.; Draper, D. C.; Ayres, B. R.; ...

    2015-09-25

    Inorganic aerosol composition was measured in the southeastern United States, a region that exhibits high aerosol mass loading during the summer, as part of the 2013 Southern Oxidant and Aerosol Study (SOAS) campaign. Measurements using a Monitor for AeRosols and GAses (MARGA) revealed two periods of high aerosol nitrate (NO3−) concentrations during the campaign. These periods of high nitrate were correlated with increased concentrations of supermicron crustal and sea spray aerosol species, particularly Na+ and Ca2+, and with a shift towards aerosol with larger (1 to 2.5 μm) diameters. We suggest this nitrate aerosol forms by multiphase reactions of HNO3more » and particles, reactions that are facilitated by transport of crustal dust and sea spray aerosol from a source within the United States. The observed high aerosol acidity prevents the formation of NH4NO3, the inorganic nitrogen species often dominant in fine-mode aerosol at higher pH. In addition, calculation of the rate of the heterogeneous uptake of HNO3 on mineral aerosol supports the conclusion that aerosol NO3− is produced primarily by this process, and is likely limited by the availability of mineral cation-containing aerosol surface area. Modeling of NO3− and HNO3 by thermodynamic equilibrium models (ISORROPIA II and E-AIM) reveals the importance of including mineral cations in the southeastern United States to accurately balance ion species and predict gas–aerosol phase partitioning.« less

  15. Performance evaluation of newly developed portable aerosol sizers used for nanomaterial aerosol measurements.

    PubMed

    Yamada, Maromu; Takaya, Mitsutoshi; Ogura, Isamu

    2015-01-01

    Nanomaterial particles exhibit a wide range of sizes through the formation of agglomerates/aggregates. To assess nanomaterial exposure in the workplace, accurate measurements of particle concentration and size distribution are needed. In this study, we evaluated the performance of two recently commercialized instruments: a portable scanning mobility particle sizer (SMPS) (NanoScan, TSI Inc.), which measures particle size distribution between 10 and 420 nm and an optical particle sizer (OPS, TSI Inc.), which measures particle size distribution between 300 and 10,000 nm. We compared the data measured by these instruments to conventional instruments (i.e., a widely used laboratory SMPS and an optical particle counter (OPC)) using nano-TiO(2) powder as test aerosol particles. The results showed obvious differences in the size distributions between the new and old SMPSs. A possible reason for the differences is that the cyclone inlet of the new SMPS (NanoScan) acted as a disperser of the weakly agglomerated particles and consequently the concentration increased through the breakup of the agglomerates. On the other hand, the particle concentration and size distributions measured by the OPS were similar to the OPC. When indoor aerosol particles were measured, the size distribution measured by the NanoScan was similar to the laboratory SMPS.

  16. Ground-Based Aerosol Measurements

    EPA Science Inventory

    Atmospheric particulate matter (PM) is a complex chemical mixture of liquid and solid particles suspended in air (Seinfeld and Pandis 2016). Measurements of this complex mixture form the basis of our knowledge regarding particle formation, source-receptor relationships, data to ...

  17. Ground-Based Aerosol Measurements

    EPA Science Inventory

    Atmospheric particulate matter (PM) is a complex chemical mixture of liquid and solid particles suspended in air (Seinfeld and Pandis 2016). Measurements of this complex mixture form the basis of our knowledge regarding particle formation, source-receptor relationships, data to ...

  18. LOAC: a small aerosol optical counter/sizer for ground-based and balloon measurements of the size distribution and nature of atmospheric particles - Part 2: First results from balloon and unmanned aerial vehicle flights

    NASA Astrophysics Data System (ADS)

    Renard, Jean-Baptiste; Dulac, François; Berthet, Gwenaël; Lurton, Thibaut; Vignelles, Damien; Jégou, Fabrice; Tonnelier, Thierry; Jeannot, Matthieu; Couté, Benoit; Akiki, Rony; Verdier, Nicolas; Mallet, Marc; Gensdarmes, François; Charpentier, Patrick; Mesmin, Samuel; Duverger, Vincent; Dupont, Jean-Charles; Elias, Thierry; Crenn, Vincent; Sciare, Jean; Zieger, Paul; Salter, Matthew; Roberts, Tjarda; Giacomoni, Jérôme; Gobbi, Matthieu; Hamonou, Eric; Olafsson, Haraldur; Dagsson-Waldhauserova, Pavla; Camy-Peyret, Claude; Mazel, Christophe; Décamps, Thierry; Piringer, Martin; Surcin, Jérémy; Daugeron, Daniel

    2016-08-01

    In the companion (Part I) paper, we have described and evaluated a new versatile optical particle counter/sizer named LOAC (Light Optical Aerosol Counter), based on scattering measurements at angles of 12 and 60°. That allows for some typology identification of particles (droplets, carbonaceous, salts, and mineral dust) in addition to size-segregated counting in a large diameter range from 0.2 µm up to possibly more than 100 µm depending on sampling conditions (Renard et al., 2016). Its capabilities overpass those of preceding optical particle counters (OPCs) allowing the characterization of all kind of aerosols from submicronic-sized absorbing carbonaceous particles in polluted air to very coarse particles (> 10-20 µm in diameter) in desert dust plumes or fog and clouds. LOAC's light and compact design allows measurements under all kinds of balloons, on-board unmanned aerial vehicles (UAVs) and at ground level. We illustrate here the first LOAC airborne results obtained from a UAV and a variety of scientific balloons. The UAV was deployed in a peri-urban environment near Bordeaux in France. Balloon operations include (i) tethered balloons deployed in urban environments in Vienna (Austria) and Paris (France), (ii) pressurized balloons drifting in the lower troposphere over the western Mediterranean (during the Chemistry-Aerosol Mediterranean Experiment - ChArMEx campaigns), (iii) meteorological sounding balloons launched in the western Mediterranean region (ChArMEx) and from Aire-sur-l'Adour in south-western France (VOLTAIRE-LOAC campaign). More focus is put on measurements performed in the Mediterranean during (ChArMEx) and especially during African dust transport events to illustrate the original capability of balloon-borne LOAC to monitor in situ coarse mineral dust particles. In particular, LOAC has detected unexpected large particles in desert sand plumes.

  19. LOAC: a small aerosol optical counter/sizer for ground-based and balloon measurements of the size distribution and nature of atmospheric particles - Part 2: First results from balloon and unmanned aerial vehicle flights

    NASA Astrophysics Data System (ADS)

    Renard, J.-B.; Dulac, F.; Berthet, G.; Lurton, T.; Vignelles, D.; Jégou, F.; Tonnelier, T.; Thaury, C.; Jeannot, M.; Couté, B.; Akiki, R.; Verdier, N.; Mallet, M.; Gensdarmes, F.; Charpentier, P.; Mesmin, S.; Duverger, V.; Dupont, J. C.; Elias, T.; Crenn, V.; Sciare, J.; Giacomoni, J.; Gobbi, M.; Hamonou, E.; Olafsson, H.; Dagsson-Waldhauserova, P.; Camy-Peyret, C.; Mazel, C.; Décamps, T.; Piringer, M.; Surcin, J.; Daugeron, D.

    2015-09-01

    In the companion paper (Renard et al., 2015), we have described and evaluated a new versatile optical particle counter/sizer named LOAC (Light Optical Aerosol Counter) based on scattering measurements at angles of 12 and 60° that allows some topology identification of particles (droplets, carbonaceous, salts, and mineral dust) in addition to size segregated counting in a large diameter range from 0.2 up to possibly more than 100 μm depending on sampling conditions. Its capabilities overpass those of preceding optical particle counters (OPCs) allowing the characterization of all kind of aerosols from submicronic-sized absorbing carbonaceous particles in polluted air to very coarse particles (> 10-20 μm in diameter) in desert dust plumes or fog and clouds. LOAC's light and compact design allows measurements under all kinds of balloons, on-board unmanned aerial vehicles (UAV) and at ground level. We illustrate here the first LOAC airborne results obtained from an unmanned aerial vehicle (UAV) and a variety of scientific balloons. The UAV was deployed in a peri-urban environment near Bordeaux in France. Balloon operations include (i) tethered balloons deployed in urban environments in Vienna (Austria) and Paris (France), (ii) pressurized balloons drifting in the lower troposphere over the western Mediterranean (during the Chemistry-Aerosol Mediterranean Experiment - ChArMEx campaigns), (iii) meteorological sounding balloons launched in the western Mediterranean region (ChArMEx) and from Aire-sur-l'Adour in south-western France (VOLTAIRE-LOAC campaign). More focus is put on measurements performed in the Mediterranean during (ChArMEx) and especially during African dust transport events to illustrate the original capability of balloon-borne LOAC to monitor in situ coarse mineral dust particles. In particular, LOAC has detected unexpected large particles in desert sand plumes.

  20. SAGE II aerosol correlative observations - Profile measurements

    NASA Technical Reports Server (NTRS)

    Osborn, M. T.; Rosen, J. M.; Mccormick, M. P.; Wang, Pi-Huan; Livinfston, J. M.

    1989-01-01

    Profiles of the aerosol extinction measurements from the Stratospheric Aerosol and Gas Experiment (SAGE) II are compared with profiles from five correlative experiments between November 1984 and July 1986. The correlative profiles were derived from six-channel dustsonde measurements and two-wavelength lidar backscatter data. The correlation between the dustsonde- and lidar-derived measurements and the SAGE II data is good, validating the SAGE II lower stratospheric aerosol extinction measurements.

  1. Inhomogeneities in particle composition of single, levitated aerosol particles observed by Mie resonance spectroscopy

    NASA Astrophysics Data System (ADS)

    Krieger, Ulrich; Lienhard, Daniel; Bastelberger, Sandra; Steimer, Sarah

    2014-05-01

    Recent observations have indicated that organic aerosol particles in the atmosphere may exist in an amorphous semi-solid or even solid (i.e. glassy) state, e.g. [1]. The influence of highly viscous and glassy states on the timescale of aerosol particle equilibration with respect to water vapor have been investigated for some model systems of atmospheric aerosol, e.g. [2,3]. In particular, it has been shown that the kinetics of the water absorption/desorption process is controlled entirely by liquid-phase diffusion of water molecules for a highly viscous aerosol particle. A liquid phase diffusion model based on numerically solving the non-linear diffusion equation predicts strong internal gradients in water concentration when condensed phase diffusion impedes the water uptake from the gas phase [2]. Here we observe and quantify the internal concentration gradients in single, levitated, micron size aerosol particles of aqueous shikimic acid using elastic Mie resonance spectroscopy. A single, aqueous particle is levitated in an electro-dynamic balance (for details see [2]), dried for several days at room temperature, cooled to the target temperature and exposed to a rapid change in relative humidity. In addition to measuring the elastically backscattered light of a "white light" LED source and recording the full spectrum with a spectrograph as in [2], we use a tunable diode laser (TDL) to scan high resolution TE- and TM spectra. This combination allows observing various Mie resonance mode orders simultaneously. Since we perform the experiment at low temperatures and low humidities the changes in the Mie-spectra due to water uptake are sufficiently slow to resolve the kinetics. Experimental Mie resonance spectra are inverted to concentration profiles of water within the particle by applying the numerical diffusion model [2] in conjunction with Mie calculations of multilayered spheres [4]. [1] A. Virtanen et al. (2010): An amorphous solid state of biogenic secondary

  2. Single particle diversity and mixing state measurements

    NASA Astrophysics Data System (ADS)

    Healy, R. M.; Riemer, N.; Wenger, J. C.; Murphy, M.; West, M.; Poulain, L.; Wiedensohler, A.; O'Connor, I. P.; McGillicuddy, E.; Sodeau, J. R.; Evans, G. J.

    2014-02-01

    A newly developed framework for quantifying aerosol particle diversity and mixing state based on information-theoretic entropy is applied for the first time to single particle mass spectrometry field data. Single particle mass fraction estimates for black carbon, organic aerosol, ammonium, nitrate and sulphate, derived using single particle mass spectrometer, aerosol mass spectrometer and multi-angle absorption photometer measurements are used to calculate single particle species diversity (Di). The average single particle species diversity (Dα) is then related to the species diversity of the bulk population (Dγ) to derive a mixing state index value (χ) at hourly resolution. The mixing state index is a single parameter representation of how internally/externally mixed a particle population is at a given time. The index describes a continuum, with values of 0% and 100% representing fully external and internal mixing, respectively. This framework was applied to data collected as part of the MEGAPOLI winter campaign in Paris, France 2010. Di values are low (∼2) for fresh traffic and woodburning particles that contain high mass fractions of black carbon and organic aerosol but low mass fractions of inorganic ions. Conversely, Di values are higher (∼4) for aged carbonaceous particles containing similar mass fractions of black carbon, organic aerosol, ammonium, nitrate and sulphate. Aerosol in Paris is estimated to be 59% internally mixed in the size range 150-1067 nm, and mixing state is dependent both upon time of day and air mass origin. Daytime primary emissions associated with vehicular traffic and woodburning result in low χ values, while enhanced condensation of ammonium nitrate on existing particles at night leads to higher χ values. Advection of particles from continental Europe containing ammonium, nitrate and sulphate leads to increases in Dα, Dγ and χ. The mixing state index represents a useful metric by which to compare and contrast ambient

  3. Single particle diversity and mixing state measurements

    NASA Astrophysics Data System (ADS)

    Healy, R. M.; Riemer, N.; Wenger, J. C.; Murphy, M.; West, M.; Poulain, L.; Wiedensohler, A.; O'Connor, I. P.; McGillicuddy, E.; Sodeau, J. R.; Evans, G. J.

    2014-06-01

    A newly developed framework for quantifying aerosol particle diversity and mixing state based on information-theoretic entropy is applied for the first time to single particle mass spectrometry field data. Single particle mass fraction estimates for black carbon, organic aerosol, ammonium, nitrate and sulfate, derived using single particle mass spectrometer, aerosol mass spectrometer and multi-angle absorption photometer measurements are used to calculate single particle species diversity (Di). The average single particle species diversity (Dα) is then related to the species diversity of the bulk population (Dγ) to derive a mixing state index value (χ) at hourly resolution. The mixing state index is a single parameter representation of how internally/externally mixed a particle population is at a given time. The index describes a continuum, with values of 0 and 100% representing fully external and internal mixing, respectively. This framework was applied to data collected as part of the MEGAPOLI winter campaign in Paris, France, 2010. Di values are low (~ 2) for fresh traffic and wood-burning particles that contain high mass fractions of black carbon and organic aerosol but low mass fractions of inorganic ions. Conversely, Di values are higher (~ 4) for aged carbonaceous particles containing similar mass fractions of black carbon, organic aerosol, ammonium, nitrate and sulfate. Aerosol in Paris is estimated to be 59% internally mixed in the size range 150-1067 nm, and mixing state is dependent both upon time of day and air mass origin. Daytime primary emissions associated with vehicular traffic and wood-burning result in low χ values, while enhanced condensation of ammonium nitrate on existing particles at night leads to higher χ values. Advection of particles from continental Europe containing ammonium, nitrate and sulfate leads to increases in Dα, Dγ and χ. The mixing state index represents a useful metric by which to compare and contrast ambient particle

  4. Microphysical processing of aerosol particles in orographic clouds

    NASA Astrophysics Data System (ADS)

    Pousse-Nottelmann, S.; Zubler, E. M.; Lohmann, U.

    2015-01-01

    An explicit and detailed treatment of cloud-borne particles allowing for the consideration of aerosol cycling in clouds has been implemented in the regional weather forecast and climate model COSMO. The effects of aerosol scavenging, cloud microphysical processing and regeneration upon cloud evaporation on the aerosol population and on subsequent cloud formation are investigated. For this, two-dimensional idealized simulations of moist flow over two bell-shaped mountains were carried out varying the treatment of aerosol scavenging and regeneration processes for a warm-phase and a mixed-phase orographic cloud. The results allowed to identify different aerosol cycling mechanisms. In the simulated non-precipitating warm-phase cloud, aerosol mass is incorporated into cloud droplets by activation scavenging and released back to the atmosphere upon cloud droplet evaporation. In the mixed-phase cloud, a first cycle comprises cloud droplet activation and evaporation via the Wegener-Bergeron-Findeisen process. A second cycle includes below-cloud scavenging by precipitating snow particles and snow sublimation and is connected to the first cycle via the riming process which transfers aerosol mass from cloud droplets to snow flakes. In the simulated mixed-phase cloud, only a negligible part of the total aerosol mass is incorporated into ice crystals. Sedimenting snow flakes reaching the surface remove aerosol mass from the atmosphere. The results show that aerosol processing and regeneration lead to a vertical redistribution of aerosol mass and number. However, the processes not only impact the total aerosol number and mass, but also the shape of the aerosol size distributions by enhancing the internally mixed/soluble accumulation mode and generating coarse mode particles. Concerning subsequent cloud formation at the second mountain, accounting for aerosol processing and regeneration increases the cloud droplet number concentration with possible implications for the ice

  5. Microphysical processing of aerosol particles in orographic clouds

    NASA Astrophysics Data System (ADS)

    Pousse-Nottelmann, S.; Zubler, E. M.; Lohmann, U.

    2015-08-01

    An explicit and detailed treatment of cloud-borne particles allowing for the consideration of aerosol cycling in clouds has been implemented into COSMO-Model, the regional weather forecast and climate model of the Consortium for Small-scale Modeling (COSMO). The effects of aerosol scavenging, cloud microphysical processing and regeneration upon cloud evaporation on the aerosol population and on subsequent cloud formation are investigated. For this, two-dimensional idealized simulations of moist flow over two bell-shaped mountains were carried out varying the treatment of aerosol scavenging and regeneration processes for a warm-phase and a mixed-phase orographic cloud. The results allowed us to identify different aerosol cycling mechanisms. In the simulated non-precipitating warm-phase cloud, aerosol mass is incorporated into cloud droplets by activation scavenging and released back to the atmosphere upon cloud droplet evaporation. In the mixed-phase cloud, a first cycle comprises cloud droplet activation and evaporation via the Wegener-Bergeron-Findeisen (WBF) process. A second cycle includes below-cloud scavenging by precipitating snow particles and snow sublimation and is connected to the first cycle via the riming process which transfers aerosol mass from cloud droplets to snowflakes. In the simulated mixed-phase cloud, only a negligible part of the total aerosol mass is incorporated into ice crystals. Sedimenting snowflakes reaching the surface remove aerosol mass from the atmosphere. The results show that aerosol processing and regeneration lead to a vertical redistribution of aerosol mass and number. Thereby, the processes impact the total aerosol number and mass and additionally alter the shape of the aerosol size distributions by enhancing the internally mixed/soluble Aitken and accumulation mode and generating coarse-mode particles. Concerning subsequent cloud formation at the second mountain, accounting for aerosol processing and regeneration increases

  6. International Workshop on Stratospheric Aerosols: Measurements, Properties, and Effects

    NASA Technical Reports Server (NTRS)

    Pueschel, Rudolf F. (Editor)

    1991-01-01

    Following a mandate by the International Aerosol Climatology Program under the auspices of International Association of Meteorology and Atmospheric Physics International Radiation Commission, 45 scientists from five nations convened to discuss relevant issues associated with the measurement, properties, and effects of stratospheric aerosols. A summary is presented of the discussions on formation and evolution, transport and fate, effects on climate, role in heterogeneous chemistry, and validation of lidar and satellite remote sensing of stratospheric aerosols. Measurements are recommended of the natural (background) and the volcanically enhanced aerosol (sulfuric acid and silica particles), the exhaust of shuttle, civil aviation and supersonic aircraft operations (alumina, soot, and ice particles), and polar stratospheric clouds (ice, condensed nitric and hydrochloric acids).

  7. Relationship between aerosol oxidation level and hygroscopic properties of laboratory generated secondary organic aerosol (SOA) particles

    NASA Astrophysics Data System (ADS)

    Massoli, P.; Lambe, A.; Ahern, A.; Williams, L. R.; Ehn, M.; Mikkila, J.; Canagaratna, M.; Brune, W. H.; Onasch, T. B.; Jayne, J.; Petdjd, T. T.; Kulmala, M. T.; Laaksonen, A.; Kolb, C. E.; Davidovits, P.; Worsnop, D. R.

    2010-12-01

    Laboratory experiments investigated the relationship between degree of oxidation and hygroscopic properties of secondary organic aerosol (SOA) particles. The hygroscopic growth factor (HGF), the CCN activity (κCCN) and the degree of aerosol oxidation (represented by the atomic O:C ratio) were measured for α-pinene, 1,3,5-trimethylbenzene (TMB), m-xylene and α pinene/m-xylene mixture SOA generated via OH radical oxidation in an aerosol flow reactor. Our results show that both HGF and κCCN increase with O:C. The TMB and m-xylene SOA were, respectively, the least and most hygroscopic of the system studied. An average HGF of 1.25 and a κCCN of 0.2 were measured at O:C of 0.65, in agreement with results reported for ambient data. The HGF based κ(κHGF) under predicted the κCCN values of 20 to 50% for all but the TMB SOA. Within the limitations of instrumental capabilities, we define the extent to which the hygroscopic properties of SOA particles can be predicted from their oxidation level and provide parameterizations suitable for interpreting ambient data.

  8. Physical and chemical study of single aerosol particles using optical trapping cavity ringdown spectroscopy

    DTIC Science & Technology

    2016-08-30

    display time-, particle-, or wavelength-resolved chemical properties such as single aerosol particle extinction . We demonstrate the scope by trapping...chemical properties such as single aerosol particle extinction . We demonstrate the scope by trapping and walking single carbon-nanotube particles of...well-defined single aerosol particles for spatial resolution in a single aerosol manipulation, detection limit of extinction coefficient, detection

  9. Size distribution of biogenic aerosol particles from the amazon basin

    NASA Astrophysics Data System (ADS)

    Artaxo, Paulo; Hansson, Hans-Christen

    The size distribution and elemental composition of natural background aerosol particles from the tropical rain forest of the Amazon Basin were measured. A 45 m high tower installed in an undisturbed forest near Manaus was used and aerosol was sampled in three levels of the tower. Single orifice Batelle-type cascade impactors with 5 stages and backup filter were used. A total of 50 complete cascade impactor sets was sampled in April and May 1987, during the wet season, when no forest burning occurs. Particle-induced X-ray emission (PIXE) was used to measure elemental concentrations of 20 elements (Al, Si, P, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Br, Rb, Sr, Zr and Pb). Absolute factor analysis was used to interpret the large data set of the trace element concentrations and to obtain quantitative elemental source profiles. The identified components in all size ranges comprise biogenic aerosol naturally released by the forest, mineral dust aerosol particles and sea salt. The elements associated with the biogenic component were potassium, phosphorus, sulphur, zinc, strontium and others in smaller proportions. The mineral dust component comprises most of the concentration of aluminium, silicon, calcium, titanium, manganese and iron. Chlorine was found to be associated with the aeolean dust component because of the long-range transport of Sahara dust over the Atlantic ocean, bringing Cl together with mineral dust particles. The size distribution of the elements associated with the windblown dust (Al, Si, Ca, Ti, Mn, Fe and Cl) shows in the coarse mode, with an average aerodynamic diameter of 4 μm. Two different biogenic aerosol components were observed. A fine mode component ( d50 ≈ 0.5 μm), characterised by the the elements S, Zn and Sr and the mode biogenic component ( d50 ≈ 3.0 μm) characterised by the presence of P, K, Cl and Sr. The coarse biogenic (P, K, Cl, Sr) component is predominant at ground level under the forest canopy. The fine mode biogenic

  10. Photoacoustic measurements of photokinetics in single optically trapped aerosol droplets

    NASA Astrophysics Data System (ADS)

    Covert, Paul; Cremer, Johannes; Signorell, Ruth; Thaler, Klemens; Haisch, Christoph

    2017-04-01

    It is well established that interaction of light with atmospheric aerosols has a large impact on the Earth's climate. However, uncertainties in the magnitude of this impact remain large, due in part to broad distributions of aerosol size, composition, and chemical reactivity. In this context, photoacoustic spectroscopy is commonly used to measure light absorption by aerosols. Here, we present photoacoustic measurements of single, optically-trapped nanodroplets to reveal droplet size-depencies of photochemical and physical processes. Theoretical considerations have pointed to a size-dependence in the magnitude and phase of the photoacoustic response from aerosol droplets. This dependence is thought to originate from heat transfer processes that are slow compared to the acoustic excitation frequency. In the case of a model aerosol, our measurements of single particle absorption cross-section versus droplet size confirm these theoretical predictions. In a related study, using the same model aerosol, we also demonstrate a droplet size-dependence of photochemical reaction rates [1]. Within sub-micron sized particles, photolysis rates were observed to be an order of magnitude greater than those observed in larger droplets. [1] J. W. Cremer, K. M. Thaler, C. Haisch, and R. Signorell. Photoacoustics of single laser-trapped nanodroplets for the direct observation of nanofocusing in aerosol photokinetics. Nat. Commun., 7:10941, 2016.

  11. 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.

    2008-09-01

    Atmospheric aerosol particles serving as cloud condensation nuclei (CCN) are key elements of the hydrological cycle and climate, but their abundance, properties and sources are highly variable and not well known. We have measured and characterized CCN in polluted air and biomass burning smoke during the PRIDE-PRD2006 campaign on 1 30 July 2006 at a rural site ~60 km northwest of the mega-city Guangzhou in southeastern China. CCN efficiency spectra (activated fraction vs. dry particle diameter; 20 300 nm) were recorded at water vapor supersaturations (S) in the range of 0.07% to 1.27%. Depending on S, the dry CCN activation diameters were in the range of 30 200 nm, corresponding to effective hygroscopicity parameters κ in the range of 0.1 0.5. The hygroscopicity of particles in the accumulation size range was generally higher than that of particles in the nucleation and Aitken size range. The campaign average value of κ for all aerosol particles across the investigated size range was 0.3, which equals the average value of κ for other continental locations. During a strong local biomass burning event, the activation diameters increased by ~10% and the average value of κ dropped to 0.2, which can be considered as characteristic for freshly emitted smoke from the burning of agricultural waste. At low S (≤0.27%), the maximum activated fraction remained generally well below one, which indicates substantial proportions of externally mixed CCN-inactive particles with much lower hygroscopicity most likely soot particles (up to ~60% at ~250 nm). The mean CCN number concentrations (NCCN,S) ranged from 1100 cm-3 at S=0.07% to 16 000 cm-3 at S=1.27%, representing ~7% to ~85% of the total aerosol particle number concentration. Based on the measurement data, we have tested different model approaches (power laws and κ-Köhler model) for the approximation/prediction of NCCN,S as a function of water vapor supersaturation, aerosol particle number concentration, size

  12. Improving estimates of aerosol radiative forcing through a particle-based aerosol microphysical scheme

    NASA Astrophysics Data System (ADS)

    Fierce, L.; McGraw, R. L.

    2016-12-01

    Forcing by atmospheric aerosols remains a large source of uncertainty in assessing human influences on the climate. Although global models have moved toward including more detailed representations of aerosol populations, aerosol microphysical schemes have been evaluated against benchmark models in only limited cases. Here we introduce a new framework for simulating atmospheric aerosols based on the Quadrature Method of Moments. This new aerosol model has been designed to reproduce key features of benchmark populations simulated by the particle-resolved model PartMC-MOSAIC, while tracking as little information about aerosol distributions as is necessary. The quadrature-based model simulates the aerosol evolution using a small number of weighted particles and is, therefore, decided as a reduced particle-based model. By applying principles of maximum entropy, the quadrature-based model efficiently reproduces distributions with respect to key aerosol properties, such as critical supersaturation for cloud condensation nuclei activation and optical cross sections, with high accuracy. In addition to providing an optimized aerosol model, the present study also describes how multi-scale modeling can be used as a tool for development of advanced aerosol microphysical schemes.

  13. Experimental Determination of Chemical Diffusion within Secondary Organic Aerosol Particles

    SciTech Connect

    Abramson, Evan H.; Imre, D.; Beranek, Josef; Wilson, Jacqueline; Zelenyuk, Alla

    2013-02-28

    Formation, properties, transformations, and temporal evolution of secondary organic aerosols (SOA) particles strongly depend on particle phase. Recent experimental evidence from a number of groups indicates that SOA is in a semi-solid phase, the viscosity of which remained unknown. We find that when SOA is made in the presence of vapors of volatile hydrophobic molecules the SOA particles absorb and trap them. Here, we illustrate that it is possible to measure the evaporation rate of these molecules that is determined by their diffusion in SOA, which is then used to calculate a reasonably accurate value for the SOA viscosity. We use pyrene as a tracer molecule and a-pinene SOA as an illustrative case. It takes ~24 hours for half the pyrene to evaporate to yield a viscosity of 10^8 Pa s for a-pinene. This viscosity is consistent with measurements of particle bounce and evaporation rates. We show that viscosity of 10^8 Pa s implies coalescence times of minutes, consistent with the findings that SOA particles are spherical. Similar measurements on aged SOA particles doped with pyrene yield a viscosity of 10^9 Pa s, indicating that hardening occurs with time, which is consistent with observed decrease in water uptake and evaporation rate with aging.

  14. Electrospray ionizer for mass spectrometry of aerosol particles

    DOEpatents

    He, Siqin; Hogan, Chris; Li, Lin; Liu, Benjamin Y. H.; Naqwi, Amir; Romay, Francisco

    2017-09-19

    A device and method are disclosed to apply ESI-based mass spectroscopy to submicrometer and nanometer scale aerosol particles. Unipolar ionization is utilized to charge the particles in order to collect them electrostatically on the tip of a tungsten rod. Subsequently, the species composing the collected particles are dissolved by making a liquid flow over the tungsten rod. This liquid with dissolved aerosol contents is formed into highly charged droplets, which release unfragmented ions for mass spectroscopy, such as time-of-flight mass spectroscopy. The device is configured to operate in a switching mode, wherein aerosol deposition occurs while solvent delivery is turned off and vice versa.

  15. Transported acid aerosols measured in southern Ontario

    NASA Astrophysics Data System (ADS)

    Keeler, Gerald J.; Spengler, John D.; Koutrakis, Petros; Allen, George A.; Raizenne, Mark; Stern, Bonnie

    During the period 29 June 1986-9 August 1986, a field health study assessing the acute health effects of air pollutants on children was conducted at a summer girls' camp on the northern shore of Lake Erie in SW Ontario. Continuous air pollution measurements of SO 2, O 3, NO x, particulate sulfates, light scattering, and meteorological measurements including temperature, dew point, and wind speed and direction were made. Twelve-hour integrated samples of size fractioned particles were also obtained using dichotomous samplers and Harvard impactors equipped with an ammonia denuder for subsequent hydrogen ion determination. Particulate samples were analyzed for trace elements by X-ray fluorescence and Neutron Activation, and for organic and elemental carbon by a thermal/optical technique. The measured aerosol was periodically very acidic with observed 12-h averaged H + concentrations in the range < 10-560 nmoles m -3. The aerosol H + appeared to represent the net strong acidity after H 2SO 4 reaction with NH 3(g). Average daytime concentrations were higher than night-time for aerosol H +, sulfate, fine mass and ozone. Prolonged episodes of atmospheric acidity, sulfate, and ozone were associated with air masses arriving at the measurement site from the west and from the southwest over Lake Erie. Sulfate concentrations measured at the lakeshore camp were more than twice those measured at inland sites during extreme pollution episodes. The concentration gradient observed with onshore flow was potentially due to enhanced deposition near the lakeshore caused by discontinuities in the meteorological fields in this region.

  16. Measurements of Ocean Derived Aerosol Over the North Atlantic

    NASA Astrophysics Data System (ADS)

    Bates, T. S.; Quinn, P.; Frossard, A. A.; Russell, L. M.; Hakala, J. P.; Kieber, D. J.; Keene, W. C.

    2012-12-01

    Breaking waves on the ocean surface inject sea spray particles into the atmosphere which can act as CCN. Characterization of particles freshly emitted from the ocean surface requires a sampling method that is able to isolate those particles and prevent them from interacting with ambient gases and particles. Here we report measurements of particles directly emitted from the ocean using a newly developed in-situ particle generator (Sea Sweep). The Sea Sweep was deployed alongside RV Ronald H. Brown in the North Atlantic during August of 2012 in two contrasting regions; one in the eutrophic waters on Georges Bank and one in the oligotrophic waters near Bermuda. Bubbles were generated 0.75 m below the ocean surface with stainless steel frits and swept into a hood/vacuum hose to feed a suite of aerosol instrumentation on board the ship. The measured aerosol properties from the two regions will be compared.

  17. Measurement of coarse aerosols in workplaces. A review.

    PubMed

    Vincent, J H

    1994-01-01

    Coarse aerosol fractions in workplaces are sampled if it is felt that particles of all sizes may pose a risk to health. Although the so-called 'total' aerosol has been widely used to refer to the relevant coarse fraction, practical measurement has been very dependent on the actual sampling instrument used. This in turn has led to great uncertainty about what was being measured. In the 1980s, the concept of inhalability was proposed, based on the aerosol particle size fraction that enters the human head through the nose and/or mouth during breathing. Now there is substantial agreement by most of the world's major criteria-setting bodies on a quantitative definition taking the form of a single curve describing the probability of inhalation as a function of particle aerodynamic diameter. This definition now forms a truly health-related 'yardstick' against which to assess the performances of practical sampling devices. In turn, more and more countries are beginning to adopt the new criterion for health-related aerosol measurement in their standards, replacing the old 'total' aerosol concept. Experiments in wind tunnels to investigate the performances of previous samplers for 'total' aerosol show that most of them do not satisfactorily match the new inhalability criterion. A small number of samplers designed specifically for the inhalable fraction have been proposed and are available commercially. They include samplers for both static (or area) and personal sampling.

  18. Hygroscopicity and chemical composition of Antarctic sub-micrometre aerosol particles and observations of new particle formation

    NASA Astrophysics Data System (ADS)

    Asmi, E.; Frey, A.; Virkkula, A.; Ehn, M.; Manninen, H. E.; Timonen, H.; Tolonen-Kivimäki, O.; Aurela, M.; Hillamo, R.; Kulmala, M.

    2009-12-01

    The Antarctic near-coastal sub-micrometre aerosol particle features in summer were characterised based on measured data on aerosol hygroscopicity, size distributions, volatility and chemical ion and organic carbon mass concentrations. Hysplit model was used to calculate the history of the air masses to predict the particle origin. Additional measurements of meteorological parameters were utilised. The hygroscopic properties of particles mostly resembled those of marine aerosols. The measurements took place at 130 km from the Southern Ocean, which was the most significant factor affecting the particle properties. This is explained by the lack of additional sources on the continent of Antarctica. The Southern Ocean was thus a likely source of the particles and nucleating and condensing vapours. The particles were very hygroscopic (HGF 1.75 at 90 nm) and very volatile. Most of the sub-100 nm particle volume volatilised below 100 °C. Based on chemical data, particle hygroscopic and volatile properties were explained by a large fraction of non-neutralised sulphuric acid together with organic material. The hygroscopic growth factors assessed from chemical data were similar to measured. Hygroscopicity was higher in dry continental air masses compared with the moist marine air masses. This was explained by the aging of the marine organic species and lower methanesulphonic acid volume fraction together with the changes in the inorganic aerosol chemistry as the aerosol had travelled long time over the continental Antarctica. Special focus was directed in detailed examination of the observed new particle formation events. Indications of the preference of negative over positive ions in nucleation could be detected. However, in a detailed case study, the neutral particles dominated the particle formation process. Freshly nucleated particles had the smallest hygroscopic growth factors, which increased subsequent to particle aging.

  19. Hygroscopicity and chemical composition of Antarctic sub-micrometre aerosol particles and observations of new particle formation

    NASA Astrophysics Data System (ADS)

    Asmi, E.; Frey, A.; Virkkula, A.; Ehn, M.; Manninen, H. E.; Timonen, H.; Tolonen-Kivimäki, O.; Aurela, M.; Hillamo, R.; Kulmala, M.

    2010-05-01

    The Antarctic near-coastal sub-micrometre aerosol particle features in summer were characterised based on measured data on aerosol hygroscopicity, size distributions, volatility and chemical ion and organic carbon mass concentrations. Hysplit model was used to calculate the history of the air masses to predict the particle origin. Additional measurements of meteorological parameters were utilised. The hygroscopic properties of particles mostly resembled those of marine aerosols. The measurements took place at 130 km from the Southern Ocean, which was the most significant factor affecting the particle properties. This is explained by the lack of additional sources on the continent of Antarctica. The Southern Ocean was thus a likely source of the particles and nucleating and condensing vapours. The particles were very hygroscopic (HGF 1.75 at 90 nm) and very volatile. Most of the sub-100 nm particle volume volatilised below 100 °C. Based on chemical data, particle hygroscopic and volatile properties were explained by a large fraction of non-neutralised sulphuric acid together with organic material. The hygroscopic growth factors assessed from chemical data were similar to measured. Hygroscopicity was higher in dry continental air masses compared with the moist marine air masses. This was explained by the aging of the marine organic species and lower methanesulphonic acid volume fraction together with the changes in the inorganic aerosol chemistry as the aerosol had travelled long time over the continental Antarctica. Special focus was directed in detailed examination of the observed new particle formation events. Indications of the preference of negative over positive ions in nucleation could be detected. However, in a detailed case study, the neutral particles dominated the particle formation process. Freshly nucleated particles had the smallest hygroscopic growth factors, which increased subsequent to particle aging.

  20. Practical application of in situ aerosol measurement

    SciTech Connect

    O`Hern, T.J.; Rader, D.J.

    1993-09-01

    The use of in situ, real-time measurement techniques permits the characterization of airborne droplets and particles under conditions where traditional sampling methods can fail. For example, sampling method rely on the ability to sample and transport particles without biasing the properties of interest, and often are not applicable in harsh environment. Although in situ methods offer unique opportunities in these cases, these techniques introduce new concerns and must be used carefully if accurate measurement are to be made. Several in situ measurement techniques are reviewed here. As the field is rapidly evolving, the discussion is limited to those techniques which: (1) are commercially available, (2) provide real-time output, (3) measure the aerosol size distribution. Discussion is divided between single particle counters (which provide a flux-based or temporal measurement) and ensemble techniques (which provide a concentration-based or spatial measurement). Specific techniques discussed include phase Doppler, Mie scattering, and Fraunhofer diffraction, and commercial instruments based on these techniques.

  1. Aerosol measurements in the stratocumulus project

    NASA Technical Reports Server (NTRS)

    Hudson, James G.

    1990-01-01

    Cloud Condensation Nuclei (CCN) and Condensation Nuclei (CN) were measured from the National Center for Atmospheric Research (NCAR) Electra throughout the marine stratocumulus project. The total particle concentration was measured with a condensation nucleus counter. The CCN were measured with the Desert Research Institute (DRI) instantaneous CCN spectrometer. This instrument simultaneously measures the concentration of aerosol active at up to 100 different critical supersaturations (Sc). This is accomplished by exposing the sample to a fixed supersaturation field and using the size of the droplets produced in this cloud chamber to deduce the Sc of the nuclei upon which they have grown. Droplet size is associated with Sc through a calibration which is accomplished by passing soluble aerosols of known size and composition through the cloud chamber. This procedure results in a calibration curve of Sc vs. droplet size. This then allows the channel number to be directly associated with Sc. Thus, number concentration vs. Sc is obtained and this is a CCN spectrum. Since the instrument operates continuously, the measurements at all Sc's are available simultaneously. Samples are drawn directly from the ambient air and data is displayed in nearly real time. Samples were integrated over times of about 10 seconds so that substantial spatial resolution is available. Calibrations were performed once or twice a day and were found to be consistent. Preliminary results are shown.

  2. Aerosol optical absorption measurements with photoacoustic spectroscopy

    NASA Astrophysics Data System (ADS)

    Liu, Kun; Wang, Lei; Liu, Qiang; Wang, Guishi; Tan, Tu; Zhang, Weijun; Chen, Weidong; Gao, Xiaoming

    2015-04-01

    Many parameters related to radiative forcing in climate research are known only with large uncertainties. And one of the largest uncertainties in global radiative forcing is the contribution from aerosols. Aerosols can scatter or absorb the electromagnetic radiation, thus may have negative or positive effects on the radiative forcing of the atmosphere, respectively [1]. And the magnitude of the effect is directly related to the quantity of light absorbed by aerosols [2,3]. Thus, sensitivity and precision measurement of aerosol optical absorption is crucial for climate research. Photoacoustic spectroscopy (PAS) is commonly recognized as one of the best candidates to measure the light absorption of aerosols [4]. A PAS based sensor for aerosol optical absorption measurement was developed. A 532 nm semiconductor laser with an effective power of 160 mW was used as a light source of the PAS sensor. The PAS sensor was calibrated by using known concentration NO2. The minimum detectable optical absorption coefficient (OAC) of aerosol was determined to be 1 Mm-1. 24 hours continues measurement of OAC of aerosol in the ambient air was carried out. And a novel three wavelength PAS aerosol OAC sensor is in development for analysis of aerosol wavelength-dependent absorption Angstrom coefficient. Reference [1] U. Lohmann and J. Feichter, Global indirect aerosol effects: a review, Atmos. Chem. Phys. 5, 715-737 (2005) [2] M. Z. Jacobson, Strong radiative heating due to the mixing state of black carbon in atmospheric aerosols, Nature 409, 695-697 (2001) [3] V. Ramanathan and G. Carmichae, Global and regional climate changes due to black carbon, nature geoscience 1, 221-227 (2008) [4] W.P Arnott, H. Moosmuller, C. F. Rogers, T. Jin, and R. Bruch, Photoacoustic spectrometer for measuring light absorption by aerosol: instrument description. Atmos. Environ. 33, 2845-2852 (1999).

  3. Accuracy of near-surface aerosol extinction determined from columnar aerosol optical depth measurements in Reno, NV, USA

    NASA Astrophysics Data System (ADS)

    Loría-Salazar, S. Marcela; Arnott, W. Patrick; Moosmüller, Hans

    2014-10-01

    The aim of the present work is a detailed analysis of aerosol columnar optical depth as a tool to determine near-surface aerosol extinction in Reno, Nevada, USA, during the summer of 2012. Ground and columnar aerosol optical properties were obtained by use of in situ Photoacoustic and Integrated Nephelometer and Cimel CE-318 Sun photometer instruments, respectively. Both techniques showed that seasonal weather changes and fire plumes had enormous influence on local aerosol optics. The apparent optical height followed the shape but not magnitude of the development of the convective boundary layer when fire conditions were not present. Back trajectory analysis demonstrated that a local flow known as the Washoe Zephyr circulation often induced aerosol transport from Northern California over the Sierra Nevada Mountains that increased the aerosol optical depth at 500 nm during afternoons when compared with mornings. Aerosol fine mode fraction indicated that afternoon aerosols in June and July and fire plumes in August were dominated by submicron particles, suggesting upwind urban plume biogenically enhanced evolution toward substantial secondary aerosol formation. This fine particle optical depth was inferred to be beyond the surface, thereby complicating use of remote sensing measurements for near-ground aerosol extinction measurements. It is likely that coarse mode depletes fine mode aerosol near the surface by coagulation and condensation of precursor gases.

  4. Optimized sparse-particle aerosol representations for modeling cloud-aerosol interactions

    NASA Astrophysics Data System (ADS)

    Fierce, Laura; McGraw, Robert

    2016-04-01

    Sparse representations of atmospheric aerosols are needed for efficient regional- and global-scale chemical transport models. Here we introduce a new framework for representing aerosol distributions, based on the method of moments. Given a set of moment constraints, we show how linear programming can be used to identify collections of sparse particles that approximately maximize distributional entropy. The collections of sparse particles derived from this approach reproduce CCN activity of the exact model aerosol distributions with high accuracy. Additionally, the linear programming techniques described in this study can be used to bound key aerosol properties, such as the number concentration of CCN. Unlike the commonly used sparse representations, such as modal and sectional schemes, the maximum-entropy moment-based approach is not constrained to pre-determined size bins or assumed distribution shapes. This study is a first step toward a new aerosol simulation scheme that will track multivariate aerosol distributions with sufficient computational efficiency for large-scale simulations.

  5. One year of urban background fluorescent aerosol measurements

    NASA Astrophysics Data System (ADS)

    Pope, Francis

    2016-04-01

    Online aerosol fluorescence is a popular methodology for detecting bioaerosols in the atmosphere. In recent years there has been considerable effort into refining the technique to be able to distinguish between different bioaerosol classes such as pollen, spores and bacteria. A near continuous record of aerosol fluorescence measurements has been recorded at an urban background observation site in Birmingham, UK for the year 2015. Fluorescence measurements were performed using the Biral aerosol fluorescence spectrometer (AFS) which measures both UV and visible fluorescence resulting from the excitation of aerosol particles at 280 nm. Speciation of the fluorescent particles into different bioaerosol class is possible with the AFS but the lack of particle sizing makes the task difficult compared to other techniques. In addition to the fluorescence measurements, further campaign mode measurements were also generated for size segregated total particle numbers, ozone, nitrogen oxides and other chemical species. These measurements allow for the influence of road traffic on the concentration of fluorescent particle to be determined. This presentation will provide an in depth look into how bioaerosol concentrations and speciation (pollen, spores and bacteria) change throughout the year. These changes will be linked to local and regional meteorology and climate. In particular, the consequences of the unusually warm UK winter upon bioaerosol concentrations will be highlighted.

  6. A conceptual framework for mixing structures in individual aerosol particles

    NASA Astrophysics Data System (ADS)

    Li, Weijun; Sun, Jiaxing; Xu, Liang; Shi, Zongbo; Riemer, Nicole; Sun, Yele; Fu, Pingqing; Zhang, Jianchao; Lin, Yangting; Wang, Xinfeng; Shao, Longyi; Chen, Jianmin; Zhang, Xiaoye; Wang, Zifa; Wang, Wenxing

    2016-11-01

    This study investigated the particle size- and age-dependent mixing structures of individual particles in clean and polluted air. Aerosols were classified into eight components: sea salt, mineral dust, fly ash, metal, soot, sulfates, nitrates, and organic matter (OM). Based on our aerosol classification, a particle that consists of two or more aerosol components can be defined as an internally mixed particle. Otherwise, it is considered to be an externally mixed particle. Within the internally mixed particle class, we identified four heterogeneous mixing structures: core-shell, dumbbell, OM coating, and dispersed OM, as well as one homogeneous-like mixing structure. Homogeneous-like mixing mainly occurred in fine particles (<1 µm), while the frequency of heterogeneously mixed particles increased with particle size. Our study demonstrated that particle mixing structures depend on particle size and location and evolve with time. OM-coating and core-shell structures are important indicators for particle aging in air as long as they are distant from specific emission sources. Long-range transported particles tended to have core-shell and OM-coating structures. We found that secondary aerosol components (e.g., sulfates, nitrates, and organics) determined particle mixing structures, because their phases change following particle hydration and dehydration under different relative humidities. Once externally mixed particles are transformed into internally mixed particles, they cannot revert to their former state, except when semivolatile aerosol components are involved. Categorizing mixing structures of individual particles is essential for studying their optical and hygroscopic properties and for tracing the development of their physical or chemical properties over time.

  7. Formation and growth of indoor air aerosol particles as a result of D-limonene oxidation

    NASA Astrophysics Data System (ADS)

    Vartiainen, E.; Kulmala, M.; Ruuskanen, T. M.; Taipale, R.; Rinne, J.; Vehkamäki, H.

    Oxidation of D-limonene, which is a common monoterpene, can lead to new aerosol particle formation in indoor environments. Thus, products containing D-limonene, such as citrus fruits, air refresheners, household cleaning agents, and waxes, can act as indoor air aerosol particle sources. We released D-limonene into the room air by peeling oranges and measured the concentration of aerosol particles of three different size ranges. In addition, we measured the concentration of D-limonene, the oxidant, and the concentration of ozone, the oxidizing gas. Based on the measurements we calculated the growth rate of the small aerosol particles, which were 3-10 nm in diameter, to be about 6300nmh-1, and the losses of the aerosol particles that were due to the coagulation and condensation processes. From these, we further approximated the concentration of the condensable vapour and its source rate and then calculated the formation rate of the small aerosol particles. For the final result, we calculated the nucleation rate and the maximum number of molecules in a critical cluster. The nucleation rate was in the order of 105cm-3s-1 and the number of molecules in a critical-sized cluster became 1.2. The results were in agreement with the activation theory.

  8. Measurement of resuspended aerosol in the Chernobyl area. Part III. Size distribution and dry deposition velocity of radioactive particles during anthropogenic enhanced resuspension.

    PubMed

    Garger, E K; Paretzke, H G; Tschiersch, J

    1998-10-01

    During anthropogenic activities, such as agricultural soil management and traffic on unpaved roads, size distribution measurements were performed of atmospheric particulate radionuclides at a site in the Chernobyl 30-km exclusion zone. Analysis of cascade impactor measurements showed an increase of the total atmospheric radioactivity. In the cases of harrowing by a tractor and traffic on unpaved roads, a common shape of the size distribution was found with two maxima, the first in the 2-4 microm range, the second in the 12-20 microm range. The size distributions were compared to measurements during wind-driven resuspension. Particle number concentration measurements with an Aerodynamic Particle Sizer showed a dynamic dependence of the particle concentration in different size ranges on anthropogenic action. The increase of the mean concentration was for the large particles more than one order of magnitude higher than for fine particles during anthropogenic enhanced resuspension. From the measurement of the mass concentration, the radioactive loading could be estimated. An enrichment of radionuclides on resuspended particles (compared to soil particles) was found, with the highest enrichment for large particles. Micrometeorological considerations showed that large particles may frequently be subject to medium range transport. The dry deposition velocity was measured; the mean value of 0.026 m s(-1) +/- 0.016 m s(-1) is typical for 6-9 microm diameter particles.

  9. Method of measuring charge distribution of nanosized aerosols.

    PubMed

    Kim, S H; Woo, K S; Liu, B Y H; Zachariah, M R

    2005-02-01

    In this paper, we present the development of a method to accurately measure the positive and negative charge distribution of nanosized aerosols using a tandem differential mobility analyzer (TDMA) system. From the series of TDMA measurements, the charge fraction of nanosized aerosol particles was obtained as a function of equivalent mobility particle diameter ranging from 50 to 200 nm. The capability of this new approach was implemented by sampling from a laminar diffusion flame which provides a source of highly charged particles due to naturally occurring flame ionization process. The results from the TDMA measurement provide the charge distribution of nanosized aerosols which we found to be in reasonable agreement with Boltzmann equilibrium charge distribution theory and a theory based upon charge population balance equation (PBE) combined with Fuchs theory (N.A. Fuchs, Geofis. Pura Appl. 56 (1963) 185). The theoretically estimated charge distribution of aerosol particles based on the PBE provides insight into the charging processes of nanosized aerosols surrounded by bipolar ions and electrons, and agree well with the TDMA results.

  10. Morphology and Optical Properties of Mixed Aerosol Particles

    NASA Astrophysics Data System (ADS)

    Fard, Mehrnoush M.; Krieger, Ulrich; Rudich, Yinon; Marcolli, Claudia; Peter, Thomas

    2016-04-01

    Experiments and modeling studies have shown that deliquesced aerosols can exist not only as one-phase system containing organics, inorganic salts and water, but often as two-phase systems consisting of a predominantly organic and a predominantly inorganic aqueous phase (1,2). Recent laboratory studies conducted with model mixtures representing tropospheric aerosols (1,2,3), secondary organic aerosol (SOA) from smog chamber experiments (4), and field measurements (5) suggest that liquid-liquid phase separations (LLPS) is indeed a common phenomenon in mixed organic/ inorganic particles. During LLPS, particles may adopt different morphologies mainly core-shell and partially engulfed. A core-shell configuration will have consequences for heterogeneous chemistry and hygroscopicity and as a result will alter the optical properties of the particles in particular for organic phases containing absorbing molecules, e.g. brown carbon. The primary objective of this project is to establish a method for investigating the morphology of mixed inorganic and absorbing organic compounds of atmospheric relevance and study their radiative properties before, during, and after phase transitions mainly during LLPS. This will be the first study looking into the radiative effect of LLPS in detail. Our ternary model system consist of ammonium sulfate (AS)/ Polyethylene Glycol (PEG)/ and water (H2O). Carminic acid (CA) was added as a proxy for an absorbing organic compound to the system. The behavior of single droplets of above ternary mixture was monitored during relative humidity (RH) cycles using optical microscopy. The same ternary mixture particle was levitated in an electrodynamic balance (EDB) and the change in its absorption properties was measured at varying RH. In addition, Mie-code modeling is used to predict the absorption efficiency of the same ternary system and the result will be compared with the data obtained from EDB experiment. We also intend to determine the occurrence of

  11. Relationship between aerosol oxidation level and hygroscopic properties of laboratory generated secondary organic aerosol (SOA) particles

    NASA Astrophysics Data System (ADS)

    Massoli, P.; Lambe, A. T.; Ahern, A. T.; Williams, L. R.; Ehn, M.; Mikkilä, J.; Canagaratna, M. R.; Brune, W. H.; Onasch, T. B.; Jayne, J. T.; Petäjä, T.; Kulmala, M.; Laaksonen, A.; Kolb, C. E.; Davidovits, P.; Worsnop, D. R.

    2010-12-01

    Laboratory experiments investigated the relationship between oxidation level and hygroscopic properties of secondary organic aerosol (SOA) particles generated via OH radical oxidation in an aerosol flow reactor. The hygroscopic growth factor at 90% RH (HGF90%), the CCN activity ($\\kappa$ORG,CCN) and the level of oxidation (atomic O:C ratio) of the SOA particles were measured. Both HGF90% and $\\kappa$ORG,CCN increased with O:C; the HGF90% varied linearly with O:C, while $\\kappa$ORG,CCN mostly followed a nonlinear trend. An average HGF90% of 1.25 and $\\kappa$ORG,CCN of 0.19 were measured for O:C of 0.65, in agreement with results reported for ambient data. The $\\kappa$ORG values estimated from the HGF90% ($\\kappa$ORG,HGF) were 20 to 50% lower than paired $\\kappa$ORG,CCN values for all SOA particles except 1,3,5-trimethylbenzene (TMB), the least hygroscopic of the SOA systems. Within the limitations of instrumental capabilities, we show that differences in hygroscopic behavior among the investigated SOA systems may correspond to differences in elemental composition.

  12. Dynamics of Aerosol Particles in Stationary, Isotropic Turbulence

    NASA Technical Reports Server (NTRS)

    Collins, Lance R.; Meng, Hui

    2004-01-01

    A detailed study of the dynamics of sub-Kolmogorov-size aerosol particles in stationary isotropic turbulence has been performed. The study combined direct numerical simulations (DNS; directed by Prof. Collins) and high-resolution experimental measurements (directed by Prof. Meng) under conditions of nearly perfect geometric and parametric overlap. The goal was to measure the accumulation of particles in low-vorticity regions of the flow that arises from the effect commonly referred to as preferential concentration. The grant technically was initiated on June 13, 2000; however, funding was not available until July 11, 2000. The grant was originally awarded to Penn State University (numerical simulations) and SUNY-Buffalo (experiments); however, Prof. Collins effort was moved to Cornell University on January 2002 when he joined that university. He completed the study there. A list of the specific tasks that were completed under this study is presented.

  13. Aerosol properties derived from spectral actinic flux measurements

    NASA Astrophysics Data System (ADS)

    Stark, H.; Schmidt, K. S.; Pilewskie, P.; Cozic, J.; Wollny, A. G.; Brock, C. A.; Baynard, T.; Lack, D.; Parrish, D. D.; Fehsenfeld, F. C.

    2008-12-01

    Measurement of aerosol properties is very important for understanding climate change. Aerosol optical properties influence solar radiation throughout the troposphere. According to the Working Group I report of the intergovernmental panel for climate change [IPCC, 2007], aerosols have a direct radiative forcing of - 0.5±0.4 W/m2 with a medium to low level of scientific understanding. This relatively large uncertainty indicates the need for more frequent and precise measurements of aerosol properties. We will show how actinic flux measurements can be used to derive important optical aerosol parameters such as aerosol optical thickness and depth, surface albedo, angstrom exponent, radiative forcing by clouds and aerosols, aerosol extinction, and others. The instrument used for this study is a combination of two spectroradiometers measuring actinic flux in the ultraviolet and visible radiation range from 280 to 690 nm with a resolution of 1 nm. Actinic flux is measured as the radiation incident on a spherical surface with sensitivity independent of direction. In contrast, irradiance is measured as the radiation incident on a plane surface, which depends on the cosine of the incident angle. Our goal is to assess the capabilities of using spectral actinic flux measurements to derive various aerosol properties. Here we will compare 1) actinic flux measurements to irradiance measurements from the spectral solar flux radiometer (SSFR), 2) derived aerosol size distributions with measurements from a white light optical particle counter (WLOPC) and ultra high sensitivity aerosol size spectrometer (UHSAS), and 3) derived aerosol optical extinction with measurements from a cavity ringdown aerosol extinction spectrometer (CRD-AES). These comparisons will utilize data from three recent field campaigns over New England and the Atlantic Ocean (ICARTT 2004), Texas and the Gulf of Mexico during (TexAQS/GoMACCS 2006), and Alaska and the Arctic Ocean (ARCPAC 2008) when the instruments

  14. Aerosol particle number concentration measurements in five European cities using TSI-3022 condensation particle counter over a three-year period during health effects of air pollution on susceptible subpopulations.

    PubMed

    Aalto, Pasi; Hämeri, Kaarle; Paatero, Pentti; Kulmala, Markku; Bellander, Tom; Berglind, Niklas; Bouso, Laura; Castaño-Vinyals, Gemma; Sunyer, Jordi; Cattani, Giorgio; Marconi, Achille; Cyrys, Josef; von Klot, Stephanie; Peters, Annette; Zetzsche, Katrin; Lanki, Timo; Pekkanen, Juha; Nyberg, Fredrik; Sjövall, Billy; Forastiere, Francesco

    2005-08-01

    In this study, long-term aerosol particle total number concentration measurements in five metropolitan areas across Europe are presented. The measurements have been carried out in Augsburg, Barcelona, Helsinki, Rome, and Stockholm using the same instrument, a condensation particle counter (TSI model 3022). The results show that in all of the studied cities, the winter concentrations are higher than the summer concentrations. In Helsinki and in Stockholm, winter concentrations are higher by a factor of two and in Augsburg almost by a factor of three compared with summer months. The winter maximum of the monthly average concentrations in these cities is between 10,000 cm(-3) and 20,000 cm(-3), whereas the summer min is approximately 5000-6000 cm(-3). In Rome and in Barcelona, the winters are more polluted compared with summers by as much as a factor of 4-10. The winter maximum in both Rome and Barcelona is close to 100,000 cm(-3), whereas the summer minimum is > 10,000 cm(-3). During the weekdays the maximum of the hourly average concentrations in all of the cities is detected during the morning hours between 7 and 10 a.m. The evening maxima were present in Barcelona, Rome, and Augsburg, but these were not as pronounced as the morning ones. The daily maxima in Helsinki and Stockholm are close or even lower than the daily minima in the more polluted cities. The concentrations between these two groups of cities are different with a factor of about five during the whole day. The study pointed out the influence of the selection of the measurement site and the configuration of the sampling line on the observed concentrations.

  15. MASS SPECTROMETRY OF INDIVIDUAL AEROSOL PARTICLES. (R823980)

    EPA Science Inventory

    Typically, in real-time aerosol mass spectrometry (RTAMS), individual airborne particles
    are ablated and ionized with a single focused laser pulse. This technique yields information that
    permits bulk characterization of the particle, but information about the particle's sur...

  16. Measurements of ocean derived aerosol off the coast of California

    NASA Astrophysics Data System (ADS)

    Bates, T. S.; Quinn, P. K.; Frossard, A. A.; Russell, L. M.; Hakala, J.; PetäJä, T.; Kulmala, M.; Covert, D. S.; Cappa, C. D.; Li, S.-M.; Hayden, K. L.; Nuaaman, I.; McLaren, R.; Massoli, P.; Canagaratna, M. R.; Onasch, T. B.; Sueper, D.; Worsnop, D. R.; Keene, W. C.

    2012-06-01

    Reliable characterization of particles freshly emitted from the ocean surface requires a sampling method that is able to isolate those particles and prevent them from interacting with ambient gases and particles. Here we report measurements of particles directly emitted from the ocean using a newly developed in situ particle generator (Sea Sweep). The Sea Sweep was deployed alongside R/V Atlantis off the coast of California during May of 2010. Bubbles were generated 0.75 m below the ocean surface with stainless steel frits and swept into a hood/vacuum hose to feed a suite of aerosol instrumentation on board the ship. The number size distribution of the directly emitted, nascent particles had a dominant mode at 55-60 nm (dry diameter) and secondary modes at 30-40 nm and 200-300 nm. The nascent aerosol was not volatile at 230°C and was not enriched in SO4=, Ca++, K+, or Mg++above that found in surface seawater. The organic component of the nascent aerosol (7% of the dry submicrometer mass) volatilized at a temperature between 230 and 600°C. The submicrometer organic aerosol characterized by mass spectrometry was dominated by non-oxygenated hydrocarbons. The nascent aerosol at 50, 100, and 145 nm dry diameter behaved hygroscopically like an internal mixture of sea salt with a small organic component. The CCN/CN activation ratio for 60 nm Sea Sweep particles was near 1 for all supersaturations of 0.3 and higher indicating that all of the particles took up water and grew to cloud drop size. The nascent organic aerosol mass fraction did not increase in regions of higher surface seawater chlorophyll but did show a positive correlation with seawater dimethylsulfide (DMS).

  17. Measurements of ocean derived aerosol off the coast of California

    NASA Astrophysics Data System (ADS)

    Bates, T. S.; Quinn, P. K.; Frossard, A. A.; Russell, L. M.; Hakala, J.; PetäJä, T.; Kulmala, M.; Covert, D. S.; Cappa, C. D.; Li, S.-M.; Hayden, K. L.; Nuaaman, I.; McLaren, R.; Massoli, P.; Canagaratna, M. R.; Onasch, T. B.; Sueper, D.; Worsnop, D. R.; Keene, W. C.

    2011-11-01

    Reliable characterization of particles freshly emitted from the ocean surface requires a sampling method that is able to isolate those particles and prevent them from interacting with ambient gases and particles. Here we report measurements of particles directly emitted from the ocean using a newly developed in situ particle generator (Sea Sweep). The Sea Sweep was deployed alongside R/V Atlantis off the coast of California during May of 2010. Bubbles were generated 0.75 m below the ocean surface with stainless steel frits and swept into a hood/vacuum hose to feed a suite of aerosol instrumentation on board the ship. The number size distribution of the directly emitted, nascent particles had a dominant mode at 55-60 nm (dry diameter) and secondary modes at 30-40 nm and 200-300 nm. The nascent aerosol was not volatile at 230°C and was not enriched in SO4=, Ca++, K+, or Mg++above that found in surface seawater. The organic component of the nascent aerosol (7% of the dry submicrometer mass) volatilized at a temperature between 230 and 600°C. The submicrometer organic aerosol characterized by mass spectrometry was dominated by non-oxygenated hydrocarbons. The nascent aerosol at 50, 100, and 145 nm dry diameter behaved hygroscopically like an internal mixture of sea salt with a small organic component. The CCN/CN activation ratio for 60 nm Sea Sweep particles was near 1 for all supersaturations of 0.3 and higher indicating that all of the particles took up water and grew to cloud drop size. The nascent organic aerosol mass fraction did not increase in regions of higher surface seawater chlorophyll but did show a positive correlation with seawater dimethylsulfide (DMS).

  18. Aerosol concentration and particle size distributions in underground excavations of a hard coal mine.

    PubMed

    Skubacz, Krystian; Wojtecki, Łukasz; Urban, Paweł

    2017-09-01

    Deposition of aerosols in the respiratory system depends inter alia on their size and the respiratory tract deposition is appreciable for nanometer-sized particles. This article presents the results of measurements of size distributions of aerosols in the range of several nanometers up to about 20 μm in the underground mine excavations of an active hard coal mine. The study included practically all particles of a respirable fraction. The results showed that a high concentration of fine and ultrafine aerosols occurs in key underground workplaces especially during mining machine operations, although their contribution to total mass concentration is usually negligible.

  19. Mixing state of ambient aerosols in Nanjing city by single particle mass spectrometry

    NASA Astrophysics Data System (ADS)

    Wang, Honglei; An, Junlin; Shen, Lijuan; Zhu, Bin; Xia, Li; Duan, Qing; Zou, Jianan

    2016-05-01

    To investigate the mixing state and size-resolved aerosol in Nanjing, measurements were carried out for the period 14th January-1st February 2013 by using a Single Particle Aerosol Mass Spectrometer (SPAMS). A total of 10,864,766 particles were sized with vacuum aerodynamic diameter (dva) in the range of 0.2-2.0 μm. Of which, 1,989,725 particles were successfully ionized. Aerosol particles employed for analyzing SPAMS data utilized 96% of the hit particles to identify 5 main particle groups. The particle classes include: K-rich particles (K-CN, K-Nitrate, K-Sulfate and K-Secondary), sodium particles, ammonium particles, carbon-rich particles (OC, EC and OCEC) and heavy-metal particles (Fe-Secondary, Pb-Nitrate, Cu-Mn-Secondary and V-Secondary). EC was the largest contributor with a fraction of 21.78%, followed by K-Secondary (17.87%), K-Nitrate (12.68%) and K-CN (11.25%). High particle level and high RH (relative humidity) are two important factors decreasing visibility in Nanjing. Different particle classes have distinct extinction effects. It anti-correlated well with visibility for the K-secondary, sodium, ammonium, EC, Fe-Secondary and K-Nitrate particles. The proportion of EC particles at 0.65-1.4 μm was up to 25% on haze days and was below 10% on clean days.

  20. Detailed Aerosol Characterization using Polarimetric Measurements

    NASA Astrophysics Data System (ADS)

    Hasekamp, Otto; di Noia, Antonio; Stap, Arjen; Rietjens, Jeroen; Smit, Martijn; van Harten, Gerard; Snik, Frans

    2016-04-01

    Anthropogenic aerosols are believed to cause the second most important anthropogenic forcing of climate change after greenhouse gases. In contrast to the climate effect of greenhouse gases, which is understood relatively well, the negative forcing (cooling effect) caused by aerosols represents the largest reported uncertainty in the most recent assessment of the International Panel on Climate Change (IPCC). To reduce the large uncertainty on the aerosol effects on cloud formation and climate, accurate satellite measurements of aerosol optical properties (optical thickness, single scattering albedo, phase function) and microphysical properties (size distribution, refractive index, shape) are essential. There is growing consensus in the aerosol remote sensing community that multi-angle measurements of intensity and polarization are essential to unambiguously determine all relevant aerosol properties. This presentations adresses the different aspects of polarimetric remote sensing of atmospheric aerosols, including retrieval algorithm development, validation, and data needs for climate and air quality applications. During past years, at SRON-Netherlands Instite for Space Research retrieval algorithms have been developed that make full use of the capabilities of polarimetric measurements. We will show results of detailed aerosol properties from ground-based- (groundSPEX), airborne- (NASA Research Scanning Polarimeter), and satellite (POLDER) measurements. Also we will discuss observational needs for future instrumentation in order to improve our understanding of the role of aerosols in climate change and air quality.

  1. The Finokalia Aerosol Measurement Experiment - 2008 (FAME-08): an overview

    NASA Astrophysics Data System (ADS)

    Pikridas, M.; Bougiatioti, A.; Hildebrandt, L.; Engelhart, G. J.; Kostenidou, E.; Mohr, C.; Prevot, A. S. H.; Kouvarakis, G.; Zarmpas, P.; Burkhart, J. F.; Lee, B.-H.; Psichoudaki, M.; Mihalopoulos, N.; Pilinis, C.; Stohl, A.; Baltensperger, U.; Kulmala, M.; Pandis, S. N.

    2010-03-01

    A month (4 May to 8 June 2008) of ambient aerosol, air ion and gas phase sampling (Finokalia Aerosol Measurement Experiment 2008, FAME-08) was conducted at Finokalia, on the island of Crete, Greece. The purpose of the study was to characterize the physical and chemical properties of aged aerosol and to investigate new particle formation. Measurements included aerosol and air ion size distributions, size-resolved chemical composition, organic aerosol thermal volatility, water uptake and particle optical properties (light scattering and absorption). Statistical analysis of the aerosol mass concentration variations revealed the absence of diurnal patterns suggesting the lack of strong local sources. Sulfates accounted for approximately half of the particulate matter less than 1 micrometer in diameter (PM1) and organics for 26%. The PM1 organic aerosol fraction was highly oxidized with 80% water soluble. The supermicrometer particles were dominated by crustal components (50%), sea salt (24%) and nitrates (16%). The organic carbon to elemental carbon (OC/EC) ratio correlated with ozone measurements but with a one-day lag. The average OC/EC ratio for the study period was equal to 5.4. For three days air masses from North Africa resulted in a 6-fold increase of particulate matter less than 10 micrometers in diameter (PM10) and a decrease of the OC/EC ratio by a factor of 2. Back trajectory analysis, based on FLEXPART footprint plots, identified five source regions (Athens, Greece, Africa, other continental and marine), each of which influenced the PM1 aerosol composition and properties. Marine air masses had the lowest PM1 concentrations and air masses from the Balkans, Turkey and Eastern Europe the highest.

  2. The Finokalia Aerosol Measurement Experiment - 2008 (FAME-08): an overview

    NASA Astrophysics Data System (ADS)

    Pikridas, M.; Bougiatioti, A.; Hildebrandt, L.; Engelhart, G. J.; Kostenidou, E.; Mohr, C.; Prévôt, A. S. H.; Kouvarakis, G.; Zarmpas, P.; Burkhart, J. F.; Lee, B.-H.; Psichoudaki, M.; Mihalopoulos, N.; Pilinis, C.; Stohl, A.; Baltensperger, U.; Kulmala, M.; Pandis, S. N.

    2010-07-01

    A month (4 May to 8 June 2008) of ambient aerosol, air ion and gas phase sampling (Finokalia Aerosol Measurement Experiment 2008, FAME-08) was conducted at Finokalia, on the island of Crete, Greece. The purpose of the study was to characterize the physical and chemical properties of aged aerosol and to investigate new particle formation. Measurements included aerosol and air ion size distributions, size-resolved chemical composition, organic aerosol thermal volatility, water uptake and particle optical properties (light scattering and absorption). Statistical analysis of the aerosol mass concentration variations revealed the absence of diurnal patterns suggesting the lack of strong local sources. Sulfates accounted for approximately half of the particulate matter less than 1 micrometer in diameter (PM1) and organics for 28%. The PM1 organic aerosol fraction was highly oxidized with 80% water soluble. The supermicrometer particles were dominated by crustal components (50%), sea salt (24%) and nitrates (16%). The organic carbon to elemental carbon (OC/EC) ratio correlated with ozone measurements but with a one-day lag. The average OC/EC ratio for the study period was equal to 5.4. For three days air masses from North Africa resulted in a 6-fold increase of particulate matter less than 10 micrometers in diameter (PM10) and a decrease of the OC/EC ratio by a factor of 2. Back trajectory analysis, based on FLEXPART footprint plots, identified five source regions (Athens, Greece, Africa, other continental and marine), each of which influenced the PM1 aerosol composition and properties. Marine air masses had the lowest PM1 concentrations and air masses from the Balkans, Turkey and Eastern Europe the highest.

  3. Measurements of Atmospheric Aerosol Vertical Distributions above Svalbard, Norway using Unmanned Aerial Systems (UAS)

    NASA Astrophysics Data System (ADS)

    Bates, T. S.; Johnson, J. E.; Stalin, S.; Telg, H.; Murphy, D. M.; Burkhart, J. F.; Quinn, P.; Storvold, R.

    2015-12-01

    Atmospheric aerosol vertical distributions were measured above Svalbard, Norway in April 2015 to investigate the processes controlling aerosol concentrations and radiative effects. The aerosol payload was flown in a NOAA/PMEL MANTA Unmanned Aerial System (UAS) on 9 flights totaling 19 flight hours. Measurements were made of particle number concentration and aerosol light absorption at three wavelengths, similar to those conducted in April 2011 (Bates et al., Atmos. Meas. Tech., 6, 2115-2120, 2013). A filter sample was collected on each flight for analyses of trace elements. Additional measurements in the aerosol payload in 2015 included aerosol size distributions obtained using a Printed Optical Particle Spectrometer (POPS) and aerosol optical depth obtained using a four wavelength miniature Scanning Aerosol Sun Photometer (miniSASP). The data show most of the column aerosol mass and resulting optical depth in the boundary layer but frequent aerosol layers aloft with high particle number concentration (2000 cm-3) and enhanced aerosol light absorption (1 Mm-1). Transport of these aerosol layers was assessed using FLEXPART particle dispersion models. The data contribute to an assessment of sources of BC to the Arctic and potential climate impacts.

  4. Equilibrium absorptive partitioning theory between multiple aerosol particle modes

    NASA Astrophysics Data System (ADS)

    Crooks, Matthew; Connolly, Paul; Topping, David; McFiggans, Gordon

    2016-10-01

    An existing equilibrium absorptive partitioning model for calculating the equilibrium gas and particle concentrations of multiple semi-volatile organics within a bulk aerosol is extended to allow for multiple involatile aerosol modes of different sizes and chemical compositions. In the bulk aerosol problem, the partitioning coefficient determines the fraction of the total concentration of semi-volatile material that is in the condensed phase of the aerosol. This work modifies this definition for multiple polydisperse aerosol modes to account for multiple condensed concentrations, one for each semi-volatile on each involatile aerosol mode. The pivotal assumption in this work is that each aerosol mode contains an involatile constituent, thus overcoming the potential problem of smaller particles evaporating completely and then condensing on the larger particles to create a monodisperse aerosol at equilibrium. A parameterisation is proposed in which the coupled non-linear system of equations is approximated by a simpler set of equations obtained by setting the organic mole fraction in the partitioning coefficient to be the same across all modes. By perturbing the condensed masses about this approximate solution a correction term is derived that accounts for many of the removed complexities. This method offers a greatly increased efficiency in calculating the solution without significant loss in accuracy, thus making it suitable for inclusion in large-scale models.

  5. A combined particle trap/HTDMA hygroscopicity study of mixed inorganic/organic aerosol particles

    NASA Astrophysics Data System (ADS)

    Zardini, A. A.; Sjogren, S.; Marcolli, C.; Krieger, U. K.; Gysel, M.; Weingartner, E.; Baltensperger, U.; Peter, T.

    2008-03-01

    Atmospheric aerosols are often mixtures of inorganic and organic material. Organics can represent a large fraction of the total aerosol mass and are comprised of water-soluble and insoluble compounds. Increasing attention was paid in the last decade to the capability of mixed inorganic/organic aerosol particles to take up water (hygroscopicity). We performed hygroscopicity measurements of internally mixed particles containing ammonium sulfate and carboxylic acids (citric, glutaric, adipic acid) in parallel with an electrodynamic balance (EDB) and a hygroscopicity tandem differential mobility analyzer (HTDMA). The organic compounds were chosen to represent three distinct physical states. During hygroscopicity cycles covering hydration and dehydration measured by the EDB and the HTDMA, pure citric acid remained always liquid, adipic acid remained always solid, while glutaric acid could be either. We show that the hygroscopicity of mixtures of the above compounds is well described by the Zdanovskii-Stokes-Robinson (ZSR) relationship as long as the two-component particle is completely liquid in the ammonium sulfate/citric acid and in the ammonium sulfate/glutaric acid cases. However, we observe significant discrepancies compared to what is expected from bulk thermodynamics when a solid component is present. We explain this in terms of a complex morphology resulting from the crystallization process leading to veins, pores, and grain boundaries which allow for water sorption in excess of bulk thermodynamic predictions caused by the inverse Kelvin effect on concave surfaces.

  6. Observations of aerosol light scattering, absorption, and particle morphology changes as a function of relative humidity

    NASA Astrophysics Data System (ADS)

    Arnott, W. P.; Lewis, K.; Paredes-Miranda, G.; Winter, S.; Day, D.; Chakrabarty, R.; Moosmuller, H.; Jimenez, J. L.; Ulbrich, I.; Huffman, A.; Onasch, T.; Trimborn, A.; Kreidenweis, S.; Carrico, C.; Wold, C.; Lincoln, E.; Freeborn, P.; Hao, W.; McMeeking, G.

    2006-12-01

    A very interesting case of smoke aerosol with very low single scattering albedo, yet very large hygroscopic growth for scattering is presented. Several samples of chamise (Adenostoma fasciculatum), a common and often dominant species in California chaparral, were recently burned at the USFS Fire Science Laboratory in Missoula Montana, and aerosol optics and chemistry were observed, along with humidity-dependent light scattering, absorption, and particle morphology. Photoacoustic measurements of light absorption by two instruments at 870 nm, one on the dry channel, one on the humidified channel, showed strong reduction of aerosol light absorption with RH above 65 percent, and yet a strong increase in light scattering was observed both at 870 nm and 550 nm with nephelometers. Multispectral measurements of aerosol light absorption indicated an Angstrom coefficient for absorption near unity for the aerosols from chamise combustion. It is argued that the hygroscopic growth of scattering is due to uptake of water by the sulfur bearing aerosol. Furthermore, the reduction of aerosol light absorption is argued to be due to the collapse of chain aggregate aerosol as the RH increases wherein the interior of aerosol does no longer contribute to absorption. Implications for biomass burning in general are that humidity processing of aerosols from this source and others like it tends to substantially increase its single scattering albedo, probably in a non-reversible manner. The chemical pathway to hygroscopicity will be addressed.

  7. Sub 2 nm Particle Characterization in Systems with Aerosol Formation and Growth

    NASA Astrophysics Data System (ADS)

    Wang, Yang

    Aerosol science and technology enable continual advances in material synthesis and atmospheric pollutant control. Among these advances, one important frontier is characterizing the initial stages of particle formation by real time measurement of particles below 2 nm in size. Sub 2 nm particles play important roles by acting as seeds for particle growth, ultimately determining the final properties of the generated particles. Tailoring nanoparticle properties requires a thorough understanding and precise control of the particle formation processes, which in turn requires characterizing nanoparticle formation from the initial stages. The knowledge on particle formation in early stages can also be applied in quantum dot synthesis and material doping. This dissertation pursued two approaches in investigating incipient particle characterization in systems with aerosol formation and growth: (1) using a high-resolution differential mobility analyzer (DMA) to measure the size distributions of sub 2 nm particles generated from high-temperature aerosol reactors, and (2) analyzing the physical and chemical pathways of aerosol formation during combustion. Part. 1. Particle size distributions reveal important information about particle formation dynamics. DMAs are widely utilized to measure particle size distributions. However, our knowledge of the initial stages of particle formation is incomplete, due to the Brownian broadening effects in conventional DMAs. The first part of this dissertation studied the applicability of high-resolution DMAs in characterizing sub 2 nm particles generated from high-temperature aerosol reactors, including a flame aerosol reactor (FLAR) and a furnace aerosol reactor (FUAR). Comparison against a conventional DMA (Nano DMA, Model 3085, TSI Inc.) demonstrated that the increased sheath flow rates and shortened residence time indeed greatly suppressed the diffusion broadening effect in a high-resolution DMA (half mini type). The incipient particle

  8. 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

    Atmospheric aerosol particles serving as Cloud Condensation Nuclei (CCN) are key elements of the hydrological cycle and climate. We measured and characterized CCN in polluted air and biomass burning smoke during the PRIDE-PRD2006 campaign from 1-30 July 2006 at a rural site ~60 km northwest of the mega-city Guangzhou in southeastern China. CCN efficiency spectra (activated fraction vs. dry particle diameter; 20-290 nm) were recorded at water vapor supersaturations (S) in the range of 0.068% to 1.27%. The corresponding effective hygroscopicity parameters describing the influence of particle composition on CCN activity were in the range of κ≍0.1-0.5. The campaign average value of κ=0.3 equals the average value of κ for other continental locations. During a strong local biomass burning event, the average value of κ dropped to 0.2, which can be considered as characteristic for freshly emitted smoke from the burning of agricultural waste. At low S (≤0.27%), the maximum activated fraction remained generally well below one, indicating substantial portions of externally mixed CCN-inactive particles with much lower hygroscopicity - most likely soot particles (up to ~60% at ~250 nm). The mean CCN number concentrations (NCCN,S) ranged from 1000 cm-3 at S=0.068% to 16 000 cm-3 at S=1.27%, which is about two orders of magnitude higher than in pristine air. Nevertheless, the ratios between CCN concentration and total aerosol particle concentration (integral CCN efficiencies) were similar to the ratios observed in pristine continental air (~6% to ~85% at S=0.068% to 1.27%). Based on the measurement data, we have tested different model approaches for the approximation/prediction of NCCN,S. Depending on S and on the model approach, the relative deviations between observed and predicted NCCN,S ranged from a few percent to several hundred percent. The largest deviations occurred at low S with a simple power law. With a Köhler model using variable κ values obtained from

  9. Aerosol classification using EARLINET measurements for an intensive observational period

    NASA Astrophysics Data System (ADS)

    Papagiannopoulos, Nikolaos; Mona, Lucia; Pappalardo, Gelsomina

    2016-04-01

    ACTRIS (Aerosols, Clouds and Trace gases Research Infrastructure Network) organized an intensive observation period during summer 2012. This campaign aimed at the provision of advanced observations of physical and chemical aerosol properties, at the delivery of information about the 3D distribution of European atmospheric aerosols, and at the monitoring of Saharan dust intrusions events. EARLINET (European Aerosol Research Lidar Network) participated in the ACTRIS campaign through the addition of measurements according to the EARLINET schedule as well as daily lidar-profiling measurements around sunset by 11 selected lidar stations for the period from 8 June - 17 July. EARLINET observations during this almost two-month period are used to characterize the optical properties and vertical distribution of long-range transported aerosol over the broader area of Mediterranean basin. The lidar measurements of aerosol intensive parameters (lidar ratio, depolarization, Angstrom exponents) are shown to vary with location and aerosol type. A methodology based on EARLINET observations of frequently observed aerosol types is used to classify aerosols into seven separate types. The summertime Mediterranean basin is prone to African dust aerosols. Two major dust events were studied. The first episode occurred from the 18 to 21 of the June and the second one lasted from 28 June to 6 July. The lidar ratio within the dust layer was found to be wavelength independent with mean values of 58±14 sr at 355 nm and 57±11 sr at 532 nm. For the particle linear depolarization ratio, mean values of 0.27±0.04 at 532 nm have been found. Acknowledgements. The financial support for EARLINET in the ACTRIS Research Infrastructure Project by the European Union's Horizon 2020 research and innovation programme under grant agreement no. 654169 and previously under grant agreement no. 262254 in the Seventh Framework Programme (FP7/2007-2013) is gratefully acknowledged.

  10. 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

  11. The effect of aerosol vertical profiles on satellite-estimated surface particle sulfate concentrations

    SciTech Connect

    Liu, Yang; Wang, Zifeng; Wang, Jun; Ferrare, Richard A.; Newsom, Rob K.; Welton, Ellsworth J.

    2011-02-15

    The aerosol vertical distribution is an important factor in determining the relationship between satellite retrieved aerosol optical depth (AOD) and ground-level fine particle pollution concentrations. We evaluate how aerosol profiles measured by ground-based lidar and simulated by models can help improve the association between AOD retrieved by the Multi-angle Imaging Spectroradiometer (MISR) and fine particle sulfate (SO4) concentrations using matched data at two lidar sites. At the Goddard Space Flight Center (GSFC) site, both lidar and model aerosol profiles marginally improve the association between SO4 concentrations and MISR fractional AODs, as the correlation coefficient between cross-validation (CV) and observed SO4 concentrations changes from 0.87 for the no-scaling model to 0.88 for models scaled with aerosol vertical profiles. At the GSFC site, a large amount of urban aerosols resides in the well-mixed boundary layer so the column fractional AODs are already excellent indicators of ground-level particle pollution. In contrast, at the Atmospheric Radiation Measurement Program (ARM) site with relatively low aerosol loadings, scaling substantially improves model performance. The correlation coefficient between CV and observed SO4 concentrations is increased from 0.58 for the no-scaling model to 0.76 in the GEOS-Chem scaling model, and the model bias is reduced from 17% to 9%. In summary, despite the inaccuracy due to the coarse horizontal resolution and the challenges of simulating turbulent mixing in the boundary layer, GEOS-Chem simulated aerosol profiles can still improve methods for estimating surface aerosol (SO4) mass from satellite-based AODs, particularly in rural areas where aerosols in the free troposphere and any long-range transport of aerosols can significantly contribute to the column AOD.

  12. Thermophoretic separation of aerosol particles from a sampled gas stream

    DOEpatents

    Postma, Arlin K.

    1986-01-01

    A method for separating gaseous samples from a contained atmosphere that includes aerosol particles uses the step of repelling particles from a gas permeable surface or membrane by heating the surface to a temperature greater than that of the surrounding atmosphere. The resulting thermophoretic forces maintain the gas permeable surface clear of aerosol particles. The disclosed apparatus utilizes a downwardly facing heated plate of gas permeable material to combine thermophoretic repulsion and gravity forces to prevent particles of any size from contacting the separating plate surfaces.

  13. Improved identification of primary biological aerosol particles using single-particle mass spectrometry

    DOE PAGES

    Zawadowicz, Maria A.; Froyd, Karl D.; Murphy, Daniel M.; ...

    2017-06-16

    Measurements of primary biological aerosol particles (PBAP), especially at altitudes relevant to cloud formation, are scarce. Single-particle mass spectrometry (SPMS) has been used to probe aerosol chemical composition from ground and aircraft for over 20 years. Here we develop a method for identifying bioaerosols (PBAP and particles containing fragments of PBAP as part of an internal mixture) using SPMS. We show that identification of bioaerosol using SPMS is complicated because phosphorus-bearing mineral dust and phosphorus-rich combustion by-products such as fly ash produce mass spectra with peaks similar to those typically used as markers for bioaerosol. We have developed a methodology tomore » differentiate and identify bioaerosol using machine learning statistical techniques applied to mass spectra of known particle types. This improved method provides far fewer false positives compared to approaches reported in the literature. The new method was then applied to two sets of ambient data collected at Storm Peak Laboratory and a forested site in Central Valley, California to show that 0.04–2 % of particles in the 200–3000 nm aerodynamic diameter range were identified as bioaerosol. In addition, 36–56 % of particles identified as biological also contained spectral features consistent with mineral dust, suggesting internal dust–biological mixtures.« less

  14. Improved identification of primary biological aerosol particles using single-particle mass spectrometry

    NASA Astrophysics Data System (ADS)

    Zawadowicz, Maria A.; Froyd, Karl D.; Murphy, Daniel M.; Cziczo, Daniel J.

    2017-06-01

    Measurements of primary biological aerosol particles (PBAP), especially at altitudes relevant to cloud formation, are scarce. Single-particle mass spectrometry (SPMS) has been used to probe aerosol chemical composition from ground and aircraft for over 20 years. Here we develop a method for identifying bioaerosols (PBAP and particles containing fragments of PBAP as part of an internal mixture) using SPMS. We show that identification of bioaerosol using SPMS is complicated because phosphorus-bearing mineral dust and phosphorus-rich combustion by-products such as fly ash produce mass spectra with peaks similar to those typically used as markers for bioaerosol. We have developed a methodology to differentiate and identify bioaerosol using machine learning statistical techniques applied to mass spectra of known particle types. This improved method provides far fewer false positives compared to approaches reported in the literature. The new method was then applied to two sets of ambient data collected at Storm Peak Laboratory and a forested site in Central Valley, California to show that 0.04-2 % of particles in the 200-3000 nm aerodynamic diameter range were identified as bioaerosol. In addition, 36-56 % of particles identified as biological also contained spectral features consistent with mineral dust, suggesting internal dust-biological mixtures.

  15. A CLOSURE STUDY OF AEROSOL MASS CONCENTRATION MEASUREMENTS: COMPARISON OF VALUES OBTAINED WITH FILTERS AND BY DIRECT MEASUREMENTS OF MASS DISTRIBUTIONS. (R826372)

    EPA Science Inventory

    We compare measurements of aerosol mass concentrations obtained gravimetrically using Teflon coated glass fiber filters and by integrating mass distributions measured with the differential mobility analyzer–aerosol particle mass analyzer (DMA–APM) technique (Aero...

  16. Sensitivity of particle size to relative humidity for Los Angeles aerosols

    SciTech Connect

    McMurry, P.H.

    1988-12-01

    A TDMA system (Tandem Differential Mobility Analyzer) was used to measure the sensitivity of particle size to relative humidity for monodisperse Los Angeles aerosols. Measurements were made at Claremont, CA on 13 days between June 19 and Sept. 3, 1987, in conjunction with the Southern California Air Quality Study (SCAQS). The particle sizes studied ranged from 0.05 micrometer to 0.5-micrometer diameter at ambient relative humidity (typically 45-65%). The data provide clear evidence that these atmospheric aerosols were externally mixed. The data also show that for the hydrophilic aerosol fraction, the larger particles (0.4-0.5 micrometer) grew more when humidified than did the smaller particles (0.05-0.2 micrometer). The report summarizes measurement results.

  17. The reconstruction of aerosol light absorption by particle measurements at remote sites: An independent analysis of data from the IMPROVE network — II

    NASA Astrophysics Data System (ADS)

    Huffman, H. Dale

    The author's mutual validation of the IMPROVE measures of light absorption — the light absorption coefficient σa and the TOR carbon measures — at remote sites in the western United States, has identified more light-absorbing carbon (LAC) than the current interpretation of TOR admits. Further comparison of σa with the new determination of LAC allows us to identify fine soil as the remaining significant contributor to light absorption at these remote sites, and thus to fully reconstruct σa there. This reconstruction also confirms the accuracy of the blank corrections to the carbon measurements. Using σa or the new reconstruction of it given herein as the appropriate measure of light absorption allows more correct reconstructions of aerosol light extinction σe and of organic mass; the latter provides evidence that the newly identified LAC is also essentially elemental carbon (EC). The new interpretation of the TOR carbons for the remote western sites also reveals apparently much less pyrolysis than previously though occurring during TOR analysis, for most of the aerosol samples collected at these sites. A very small minority population, comprising less than 5% of the samples and occurring mostly in the summer and autumn, is also identified, containing a larger proportion of supposed pyrolyzable organics. The differences in apparent makeup between the two populations strongly suggest that the majority population represents a widespread background of aerosol light absorption which averages 5 Mm -1 and is probably due primarily to diesel fuel emissions transported from urban areas and highways, while the minority population is probably due to wood fires. A number of possible explanations are offered for why the newly identified EC is not currently recognized in the TOR analysis. In particular, it is claimed that sample darkening during thermal analysis is not a reliable quantitative indication of pyrolyzable organics, particularly in the remote aerosols

  18. 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.

  19. 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.

  20. Identification of characteristic mass spectrometric markers for primary biological aerosol particles and comparison with field data from submicron pristine aerosol particles

    NASA Astrophysics Data System (ADS)

    Freutel, F.; Schneider, J.; Zorn, S. R.; Drewnick, F.; Borrmann, S.; Hoffmann, T.; Martin, S. T.

    2009-04-01

    The contribution of primary biological aerosol (PBA) to the total aerosol particle concentration is estimated to range between 25 and 80%, depending on location and season. Especially in the tropical rain forest it is expected that PBA is a major source of particles in the supermicron range, and is also an important fraction of the submicron aerosol. PBA particles like plant fragments, pollen, spores, fungi, viruses etc. contain chemical compounds as proteins, sugars, amino acids, chlorophyll, and cellular material as cellulose. For this reason we have performed mass spectrometric laboratory measurements (Aerodyne C-ToF and W-ToF AMS, single particle laser ablation instrument SPLAT) on pure submicron aerosol particles containing typical PBA compounds in order to identify typical mass spectral patterns of these compounds and to explain the observed fragmentation patterns on the basis of molecular structures. These laboratory data were compared to submicron particle mass spectra obtained during AMAZE-08 (Amazonian Aerosol CharacteriZation Experiment, Brazil, February/March 2008). The results indicate that characteristic m/z ratios for carbohydrates (e.g., glucose, saccharose, levoglucosan, mannitol) can be identified, for example m/z = 60(C2H4O2+) or m/z = 61(C2H5O2+). Certain characteristic peaks for amino acids were also identified in the laboratory experiments. In the field data from AMAZE-08, these characteristic peaks for carbohydrates and amino acids were found, and their contribution to the total organic mass was estimated to about 5%. Fragment ions from peptides and small proteins were also identified in laboratory experiments. Larger proteins, however, seem to become oxidized to CO2+ to a large extend in the vaporizing process of the AMS. Thus, detection of proteins in atmospheric aerosol particles with the AMS appears to be difficult.

  1. Holistic aerosol evaluation using synthesized aerosol aircraft measurements

    NASA Astrophysics Data System (ADS)

    Watson-Parris, Duncan; Reddington, Carly; Schutgens, Nick; Stier, Philip; Carslaw, Ken; Liu, Dantong; Allan, James; Coe, Hugh

    2016-04-01

    Despite ongoing efforts there are still large uncertainties in aerosol concentrations and loadings across many commonly used GCMs. This in turn leads to large uncertainties in the contributions of the direct and indirect aerosol forcing on climate. However, constraining these fields using earth observation data, although providing global coverage, is problematic for many reasons, including the large uncertainties in retrieving aerosol loadings. Additionally, the inability to retrieve aerosols in or around cloudy scenes leads to further sampling biases (Gryspeerdt 2015). Many in-situ studies have used regional datasets to attempt to evaluate the model uncertainties, but these are unable to provide an assessment of the models ability to represent aerosols properties on a global scale. Within the Global Aerosol Synthesis and Science Project (GASSP) we have assembled the largest collection of quality controlled, in-situ aircraft observations ever synthesized to a consistent format. This provides a global set of in-situ measurements of Cloud Condensation Nuclei (CCN) and Black Carbon (BC), amongst others. In particular, the large number of vertical profiles provided by this aircraft data allows us to investigate the vertical structure of aerosols across a wide range of regions and environments. These vertical distributions are particularly valuable when investigating the dominant processes above or below clouds where remote sensing data is not available. Here we present initial process-based assessments of the BC lifetimes and vertical distributions of CCN in the HadGEM-UKCA and ECHAM-HAM models using this data. We use point-by-point based comparisons to avoid the sampling issues associated with comparing spatio-temporal aggregations.

  2. Micro-physical properties of carbonaceous aerosol particles generated by laser ablation of a graphite target

    NASA Astrophysics Data System (ADS)

    Ajtai, T.; Utry, N.; Pintér, M.; Tápai, Cs.; Kecskeméti, G.; Smausz, T.; Hopp, B.; Bozóki, Z.; Szabó, G.

    2014-09-01

    In this work the authors propose laser ablation as a highly versatile tool for carbonaceous aerosol generation. The generated carbonaceous particles can be used as a model aerosol for atmospheric black carbon. Various microphysical properties including mass concentration, size distribution and morphology of aerosol particles generated by laser ablation of a high purity graphite sample were investigated in detail. These measurements proved that the proposed method can be used to generate both primary particles and fractal aggregates with a high yield. As a further advantage of the method the size distribution of the generated aerosol can cover a wide range, and can be tuned accurately with laser fluence, the ambient composition or with the volumetric flow rate of the carrier gas.

  3. Carbonaceous aerosol particles from common vegetation in the Grand Canyon

    SciTech Connect

    Hallock, K.A.; Mazurek, M.A. ); Cass, G.R. . Dept. of Environmental Engineering Science)

    1992-05-01

    The problem of visibility reduction in the Grand Canyon due to fine organic aerosol particles in the atmosphere has become an area of increased environmental concern. Aerosol particles can be derived from many emission sources. In this report, we focus on identifying organic aerosols derived from common vegetation in the Grand Canyon. These aerosols are expected to be significant contributors to the total atmospheric organic aerosol content. Aerosol samples from living vegetation were collected by resuspension of surface wax and resin components liberated from the leaves of vegetation common to areas of the Grand Canyon. The samples were analyzed using high-resolution gas chromatography/mass spectrometry (GC/MS). Probable identification of compounds was made by comparison of sample spectra with National Institute of Standards and Technology (NIST) mass spectral references and positive identification of compounds was made when possible by comparison with authentic standards as well as NIST references. Using these references, we have been able to positively identify the presence of n-alkane and n-alkanoic acid homolog series in the surface waxes of the vegetation sampled. Several monoterpenes, sesquiterpenes, and diterpenes were identified also as possible biogenic aerosols which may contribute to the total organic aerosol abundance leading to visibility reduction in the Grand Canyon.

  4. Carbonaceous aerosol particles from common vegetation in the Grand Canyon

    SciTech Connect

    Hallock, K.A.; Mazurek, M.A.; Cass, G.R.

    1992-05-01

    The problem of visibility reduction in the Grand Canyon due to fine organic aerosol particles in the atmosphere has become an area of increased environmental concern. Aerosol particles can be derived from many emission sources. In this report, we focus on identifying organic aerosols derived from common vegetation in the Grand Canyon. These aerosols are expected to be significant contributors to the total atmospheric organic aerosol content. Aerosol samples from living vegetation were collected by resuspension of surface wax and resin components liberated from the leaves of vegetation common to areas of the Grand Canyon. The samples were analyzed using high-resolution gas chromatography/mass spectrometry (GC/MS). Probable identification of compounds was made by comparison of sample spectra with National Institute of Standards and Technology (NIST) mass spectral references and positive identification of compounds was made when possible by comparison with authentic standards as well as NIST references. Using these references, we have been able to positively identify the presence of n-alkane and n-alkanoic acid homolog series in the surface waxes of the vegetation sampled. Several monoterpenes, sesquiterpenes, and diterpenes were identified also as possible biogenic aerosols which may contribute to the total organic aerosol abundance leading to visibility reduction in the Grand Canyon.

  5. 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.

  6. Neural networks for aerosol particles characterization

    NASA Astrophysics Data System (ADS)

    Berdnik, V. V.; Loiko, V. A.

    2016-11-01

    Multilayer perceptron neural networks with one, two and three inputs are built to retrieve parameters of spherical homogeneous nonabsorbing particle. The refractive index ranges from 1.3 to 1.7; particle radius ranges from 0.251 μm to 56.234 μm. The logarithms of the scattered radiation intensity are used as input signals. The problem of the most informative scattering angles selection is elucidated. It is shown that polychromatic illumination helps one to increase significantly the retrieval accuracy. In the absence of measurement errors relative error of radius retrieval by the neural network with three inputs is 0.54%, relative error of the refractive index retrieval is 0.84%. The effect of measurement errors on the result of retrieval is simulated.

  7. Mass Spectrometric Analysis of Pristine Aerosol Particles During the wet Season of Amazonia - Detection of Primary Biological Particles?

    NASA Astrophysics Data System (ADS)

    Schneider, J.; Zorn, S. R.; Freutel, F.; Borrmann, S.; Chen, Q.; Farmer, D. K.; Jimenez, J. L.; Flores, M.; Roldin, P.; Artaxo, P.; Martin, S. T.

    2008-12-01

    The contribution of primary biological aerosol (POA) particles to the natural organic aerosol is a subject of current research. Estimations of the POA contribution to the total aerosol particle concentration range between 25 and 80%, depending on location and season. Especially in the tropical rain forest it is expected that POA is a major source of supermicron, possibly also of submicron particles. During AMAZE (Amazonian Aerosol CharacteriZation Experiment), a field project near Manaus, Brazil, in February/March 2008, an Aerodyne ToF-AMS was equipped with a high pressure aerodynamic lens. This high pressure lens (operating pressure 14.6 torr) is designed with the objective to extend the detectable size range of the AMS into the supermicron size range where primary biological particles are expected. Size distribution measured by the AMS were compared with size distribution from an optical particle counter and indicate that the high pressure lens has a 50% cut-off at a vacuum aerodynamic diameter of about 1 μm, but still has significant transmission up to a vacuum aerodynamic diameter of about 2 μm, thus extending the detectable size range of the AMS into the coarse mode. The measuring instruments were situated in a container at ground level. The aerosol was sampled through a 40 m vertical, laminar inlet, which was heated and dried to maintain a relative humidity between 30 and 40%. The inlet was equipped with a 7 μm cut-off cyclone. Size distributions recorded with an optical particle counter parallel to the AMS show that the inlet transmitted aerosol particles up to an optically detected diameter of 10 μm. POA particles like plant fragments, pollen, spores, fungi, viruses etc. contain chemical compounds as proteins, sugars, amino acids, chlorophyll, and cellular material as cellulose. Laboratory experiments have been performed in order to identify typical mass spectral patterns of these compounds. These laboratory data were compared to size resolved particle

  8. Measurements of atmospheric aerosol vertical distributions above Svalbard, Norway, using unmanned aerial systems (UAS)

    NASA Astrophysics Data System (ADS)

    Bates, T. S.; Quinn, P. K.; Johnson, J. E.; Corless, A.; Brechtel, F. J.; Stalin, S. E.; Meinig, C.; Burkhart, J. F.

    2013-08-01

    Atmospheric aerosol vertical distributions were measured above Svalbard, Norway, in April 2011 during the Cooperative Investigation of Climate-Cryosphere Interactions campaign (CICCI). Measurements were made of the particle number concentration and the aerosol light absorption coefficient at three wavelengths. A filter sample was collected on each flight at the altitude of maximum particle number concentration. The filters were analyzed for major anions and cations. The aerosol payload was flown in a NOAA/PMEL MANTA Unmanned Aerial System (UAS). A total of 18 flights were flown during the campaign totaling 38 flight hours. The data show frequent aerosol layers aloft with high particle number concentration (1000 cm-3) and enhanced aerosol light absorption (1 Mm-1). Air mass histories of these aerosol layers were assessed using FLEXPART particle dispersion modeling. The data contribute to an assessment of sources of BC to the Arctic and potential climate impacts.

  9. Measurements of atmospheric aerosol vertical distributions above Svalbard, Norway using unmanned aerial systems

    NASA Astrophysics Data System (ADS)

    Bates, T.; Quinn, P.; Johnson, J. E.; Stalin, S.; Meinig, C.; Burkhart, J. F.

    2011-12-01

    Atmospheric aerosol vertical distributions were measured above Svalbard, Norway in April 2011 during the Coordinated Investigation of Climate-Cryosphere Interactions campaign (CICCI). Measurements were made of particle number concentration and aerosol light absorption at three wavelengths. A filter sample was collected on each flight at the altitude of maximum particle number concentration. The filters were analyzed for major anions and cations. The aerosol payload was flown in a NOAA/PMEL MANTA Unmanned Aerial System (UAS). A total of 18 flights were flown during the campaign totaling 38 flight hours. The data show frequent aerosol layers aloft with high particle number concentration (1000 cm-3) and enhanced aerosol light absorption (1 Mm-1). Transport of these aerosol layers was assessed using FLEXPART particle dispersion models. The data contribute to an assessment of sources of BC to the Arctic and potential climate impacts.

  10. Measurements of atmospheric aerosol vertical distributions above Svalbard, Norway using unmanned aerial systems (UAS)

    NASA Astrophysics Data System (ADS)

    Bates, T. S.; Quinn, P. K.; Johnson, J. E.; Corless, A.; Brechtel, F. J.; Stalin, S. E.; Meinig, C.; Burkhart, J. F.

    2013-03-01

    Atmospheric aerosol vertical distributions were measured above Svalbard, Norway in April 2011 during the Cooperative Investigation of Climate-Cryosphere Interactions campaign (CICCI). Measurements were made of the particle number concentration and the aerosol light absorption coefficient at three wavelengths. A filter sample was collected on each flight at the altitude of maximum particle number concentration. The filters were analyzed for major anions and cations. The aerosol payload was flown in a NOAA/PMEL MANTA Unmanned Aerial System (UAS). A total of 18 flights were flown during the campaign totaling 38 flight hours. The data show frequent aerosol layers aloft with high particle number concentration (1000 cm-3 and enhanced aerosol light absorption (1 Mm-1). Air mass histories of these aerosol layers were assessed using FLEXPART particle dispersion modeling. The data contribute to an assessment of sources of BC to the Arctic and potential climate impacts.

  11. Aerosol particle properties in a South American megacity

    NASA Astrophysics Data System (ADS)

    Ulke, Ana; Torres-Brizuela, Marcela; Raga, Graciela; Baumgardner, Darrel; Cancelada, Marcela

    2015-04-01

    The subtropical city of Buenos Aires is located on the western shore of Río de la Plata, on the southeastern coast of Argentina. It is the second largest metropolitan area in South America, with a population density of around 14 thousand people per km2. When all 24 counties of the Great Buenos Aires Metropolitan Area are included it is the third-largest conurbation in Latin America, with a population of around fifteen million inhabitants. The generalized worldwide trend to concentrate human activities in urban regions that continue to expand in area, threatens the local and regional environment. Air pollution in the Buenos Aires airshed is due to local sources (mainly the mobile sources, followed by the electric power plants and some industries) and to distant sources (like biomass burning, dust, marine aerosols and occasionally volcanic ash) whose products arrive in the city area due to the regional transport patterns. Previous research suggests that ambient aerosol particle concentrations should be considered an air quality problem. A field campaign was conducted in Buenos Aires in 2011 in order to characterize some aerosol particles properties measured for the first time in the city. Measurements began in mid- April and continued until December. The field observations were done in a collaborative effort between the Universities of Mexico (UNAM) and Buenos Aires (UBA). A suite of instruments was installed on the roof of an UBA laboratory and classroom buildings (34.54° S, 58.44° W) at an altitude of approximately 30 m above sea level. The measurements included the number concentration of condensation nuclei (CN) larger than approximately 50 nm, the mass concentration of particle-bound polycyclic aromatic hydrocarbons (PPAH), the scattering (Bscat) and absorption (Babs) coefficients at 550 nm and the vertical profiles of backscattered light from aerosols at a wavelength of 910 nm using a ceilometer. In addition, a weather station recorded the meteorological

  12. Development of a continuous aerosol mass concentration measurement device.

    PubMed

    Bémer, D; Thomas, D; Contal, P; Subra, I

    2003-08-01

    A dynamic aerosol mass concentration measurement device has been developed for personal sampling. Its principle consists in sampling the aerosol on a filter and monitoring the change of pressure drop over time (Delta P). Ensuring that the linearity of the Delta P = f(mass of particles per unit area of filter) relationship has been well established, the change of concentration can be deduced. The response of the system was validated in the laboratory with a 3.5 microm alumina aerosol (mass median diameter) generated inside a 1-m(3) ventilated enclosure. As the theory predicted that the mass sensitivity of the system would vary inversely with the square of the particle diameter, only sufficiently fine aerosols were able to be measured. The system was tested in the field in a mechanical workshop in the vicinity of an arc-welding station. The aerosol produced by welding is indeed particularly well-adapted due to the sub-micronic size of the particles. The device developed, despite this limitation, has numerous advantages over other techniques: robustness, compactness, reliability of calibration, and ease of use.

  13. Airborne Cavity Ring-Down Measurement of Aerosol Extinction and Scattering During the Aerosol IOP

    NASA Technical Reports Server (NTRS)

    Strawa, A. W.; Ricci, K.; Provencal, R.; Schmid, B.; Covert, D.; Elleman, R.; Arnott, P.

    2003-01-01

    Large uncertainties in the effects of aerosols on climate require improved in-situ measurements of extinction coefficient and single-scattering albedo. This paper describes preliminary results from Cadenza, a new continuous wave cavity ring-down (CW-CRD) instrument designed to address these uncertainties. Cadenza measures the aerosol extinction coefficient for 675 nm and 1550 nm light, and simultaneously measures the scattering coefficient at 675 nm. In the past year Cadenza was deployed in the Asian Dust Above Monterey (ADAM) and DOE Aerosol Intensive Operating Period (IOP) field projects. During these flights Cadenza produced measurements of aerosol extinction in the range from 0.2 to 300 Mm-1 with an estimated precision of 0.1 Min-1 for 1550 nm light and 0.2 Mm-1 for 675 nm light. Cadenza data from the ADAM and Aerosol IOP missions compared favorably with data from the other instruments aboard the CIRPAS Twin Otter aircraft and participating in those projects.= We present comparisons between the Cadenza measurements and those friom a TSI nephelometer, Particle Soot Absorption Photometer (PSAP), and the AATS 14 sun-photometer. Measurements of the optical properties of smoke and dust plumes sampled during these campaigns are presented and estimates of heating rates due to these plumes are made.

  14. High sensitivity sensor for continuous direct measurement of bipolar charged aerosols

    NASA Astrophysics Data System (ADS)

    Baxter, Karen; Jones, Chris; Fletcher-Wood, Guy

    2008-12-01

    The disruptive generation of aerosols is known to cause particles to carry electrostatic charges. Anthropogenic aerosol may have a standard deviation of charges when generated that is different to other sources or equilibrated aerosols. A simple, low cost 'Bipolar Charged Aerosol Sensor' (BCAS) has been developed to continuously measure charged aerosol in the ambient environment in real-time. Direct measurement of the current released from the charged aerosol particles when they deposit onto an electrode in a DC field is achieved using custom designed, sensitive electrometers. The mobility range of particles collected is defined by the DC field strength, air flow rate through the instrument and the electrode geometry. The mobility range of interest has been selected based on measurements made previously with a complex Laser Doppler Velocimetry (LDV) based instrument. The BCAS has been assessed in laboratory. The sensor design and initial measurement data will be discussed.

  15. 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.

  16. Measurement of nonvolatile particle number size distribution

    NASA Astrophysics Data System (ADS)

    Gkatzelis, G. I.; Papanastasiou, D. K.; Florou, K.; Kaltsonoudis, C.; Louvaris, E.; Pandis, S. N.

    2016-01-01

    An experimental methodology was developed to measure the nonvolatile particle number concentration using a thermodenuder (TD). The TD was coupled with a high-resolution time-of-flight aerosol mass spectrometer, measuring the chemical composition and mass size distribution of the submicrometer aerosol and a scanning mobility particle sizer (SMPS) that provided the number size distribution of the aerosol in the range from 10 to 500 nm. The method was evaluated with a set of smog chamber experiments and achieved almost complete evaporation (> 98 %) of secondary organic as well as freshly nucleated particles, using a TD temperature of 400 °C and a centerline residence time of 15 s. This experimental approach was applied in a winter field campaign in Athens and provided a direct measurement of number concentration and size distribution for particles emitted from major pollution sources. During periods in which the contribution of biomass burning sources was dominant, more than 80 % of particle number concentration remained after passing through the thermodenuder, suggesting that nearly all biomass burning particles had a nonvolatile core. These remaining particles consisted mostly of black carbon (60 % mass contribution) and organic aerosol (OA; 40 %). Organics that had not evaporated through the TD were mostly biomass burning OA (BBOA) and oxygenated OA (OOA) as determined from AMS source apportionment analysis. For periods during which traffic contribution was dominant 50-60 % of the particles had a nonvolatile core while the rest evaporated at 400 °C. The remaining particle mass consisted mostly of black carbon with an 80 % contribution, while OA was responsible for another 15-20 %. Organics were mostly hydrocarbon-like OA (HOA) and OOA. These results suggest that even at 400 °C some fraction of the OA does not evaporate from particles emitted from common combustion processes, such as biomass burning and car engines, indicating that a fraction of this type of OA

  17. Transmissometer versus sun photometer measurements of the aerosol optical properties

    NASA Astrophysics Data System (ADS)

    Kusmierczyk-Michulec, Jolanta; Van Eijk, Alexander M. J.; Moerman, M. M.; Cohen, L. H.; de Jong, A.; Fritz, P.

    2008-08-01

    Atmospheric aerosol particles affect the Earth's radiative balance both in the cloud-free and the cloudy atmosphere. The direct effect of aerosols is related with scattering and absorption of solar radiation, and as a consequence, reduction of the amount of radiation reaching the surface. The best parameter that quantifies this effect is the aerosol extinction, which can be derived from vertical, as well as, horizontal measurements. The purpose of this paper is to compare the aerosol optical properties registered by two types of instruments. The first is a standard 5-wavelength hand-held sun photometer yielding the vertical column extinction, the second a 7-wavelength transmissometer developed at TNO. This multi-band transmissometer provides horizontal, path-integrated transmission data at 7 wavelengths within the visible/infra red spectral range. The data used in the comparison were collected during an experiment near Scripps Pier in La Jolla near San Diego, in November 2006.

  18. Discrimination and classification of bio-aerosol particles using optical spectroscopy and scattering

    NASA Astrophysics Data System (ADS)

    Eversole, Jay D.

    2011-03-01

    For more than a decade now, there has been significant emphasis for development of sensors of agent aerosols, especially for biological warfare (BW) agents. During this period, the Naval Research Laboratory (NRL) and other labs have explored the application of optical and spectroscopic methods relevant to biological composition discrimination to aerosol particle characterization. I will first briefly attempt to establish the connection between sensor performance metrics which are statistically determined, and aerosol particle measurements through the use of computational models, and also describe the challenge of ambient background characterization that would be needed to establish more reliable and deterministic sensor performance predictions. Greater attention will then be devoted to a discussion of basic particle properties and their measurement. The NRL effort has adopted an approach based on direct measurements on individual particles, principally of elastic scatter and laser-induced fluorescence (LIF), rather than populations of particles. The development of a LIF instrument using two sequential excitation wavelengths to detect fluorescence in discrete spectral bands will be described. Using this instrument, spectral characteristics of particles from a variety of biological materials including BW agent surrogates, as well as other ``calibration'' particles and some known ambient air constituents will be discussed in terms of the dependence of optical signatures on aerosol particle composition, size and incident laser fluence. Comparison of scattering and emission measurements from particles composed of widely different taxa, as well as from similar species under different growth conditions highlight the difficulties of establishing ground truth for complex biological material compositions. One aspect that is anticipated to provide greater insight to this type of particle classification capability is the development of a fundamental computational model of

  19. 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.

  20. The Influence of Local Sources and Long-range Transport of Aerosol Particles on Aerosol Parameters Relevant for Arctic Low-level Clouds

    NASA Astrophysics Data System (ADS)

    Ickes, L.; Hoose, C.; Ekman, A.

    2016-12-01

    Arctic low-level clouds often contain both ice and water. They are highly sensitive to microphysical processes which can either sustain or break down the unstable mixed-phase state and thereby determine the longevity of the clouds and their radiative impact. The clouds are influenced by the availability of aerosol particles, which can act as ice nuclei (IN) or cloud condensation nuclei (CCN) and sometimes become the limiting factor for cloud formation. Currently it is not very well known what governs the Arctic background aerosol concentration and its variability. Therefore, it is important to quantify Arctic aerosol concentrations and the associated impact on cloud microphysics.In general, the aerosol concentration in the Arctic boundary layer is low compared to other regions. Potential sources include local marine aerosol emissions and long-range transport. The emission of local, marine aerosol particles is connected to open water and open leads (open water channels) in the pack ice. The transported aerosol types depend on the large-scale meteorology, i.e. on air mass transport.In our study we investigate how the evolution of a mixed-phase Arctic boundary layer cloud depends on different aerosol situations, i.e. if the aerosol concentrations are either predominantly governed by local sources or dominated by long-range transport. We focus on the difference in the vertical profiles for different aerosol scenarios - in case of local sources the aerosol particles are emitted at the surface, while the transported aerosol particles are introduced above the inversion. To compile the vertical profiles for different aerosol scenarios we use field measurements in combination with regional modeling.

  1. Airborne measurements of biomass burning aerosol distribution and composition in the springtime Arctic 2008

    NASA Astrophysics Data System (ADS)

    Thornberry, T.; Froyd, K. D.; Murphy, D. M.; Thomson, D. S.; Brock, C. A.; Cozic, J.; Warneke, C.; Degouw, J.; Middlebrook, A. M.; Bahreini, R.; Brioude, J.

    2008-12-01

    The springtime Arctic troposphere in 2008 was characterized by high concentrations of biomass burning aerosol. During the Aerosol, Radiation, and Cloud Processes affecting Arctic Climate (ARCPAC) campaign, airborne measurements of aerosol composition by the NOAA single particle mass spectrometer instrument (PALMS) identified biomass burning particles using an established composition tracer. Fires in northern Asia produced biomass burning aerosol that were transported to the Arctic within 3-12 days. Concentrations of biomass burning aerosols were elevated not only within well defined plumes, but also regionally throughout the Arctic. Above the boundary layer, biomass burning particles dominated the total aerosol volume and were largely responsible for the Arctic Haze observed during the period of study. The composition of plume aerosols varied according to source region, transport time, and anthropogenic influence.

  2. Aerosol measurements during the central Chilean orographic precipitation experiment

    NASA Astrophysics Data System (ADS)

    Fults, Sara Lynn

    The Central Chilean Orographic Precipitation Experiment (CCOPE) was a three-month field campaign (June, July and August 2015) that investigated winter rain events. Reported here are analyses of aerosol measurements made at a coastal site (Arauco, Chile) during CCOPE. Data was obtained using a condensation particle counter (CPC) and an aerosol spectrometer (UHSAS). Arauco CPC concentrations are compared to those measured at the NOAA station at coastal Trinidad Head, California (THD). The marine-sector averaged CPC concentration at Arauco is 3457 cm-3 +/- 2284 cm-3; at THD the average is 1171 cm-3 +/- 772 cm-3. Surprisingly, the Arauco concentrations are larger (p < 0.01). In addition, UHSAS measurements were analyzed to determine processes that shaped the ASD at Arauco. Variables analyzed included the fraction of particles smaller than 0.055 mum and moments of the UHSAS-derived aerosol size distributions. There is evidence for both primary particle sources and for new particle formation adding to the aerosol burden in oceanic air as it approaches the coast and advects onshore.

  3. LASER DESORPTION IONIZATION OF ULTRAFINE AEROSOL PARTICLES. (R823980)

    EPA Science Inventory

    On-line analysis of ultrafine aerosol particle in the 12 to 150 nm size range is performed by
    laser desorption/ionization. Particles are size selected with a differential mobility analyzer and then
    sent into a linear time-of-flight mass spectrometer where they are ablated w...

  4. LASER DESORPTION IONIZATION OF ULTRAFINE AEROSOL PARTICLES. (R823980)

    EPA Science Inventory

    On-line analysis of ultrafine aerosol particle in the 12 to 150 nm size range is performed by
    laser desorption/ionization. Particles are size selected with a differential mobility analyzer and then
    sent into a linear time-of-flight mass spectrometer where they are ablated w...

  5. Aerosol measurements at the Southern Great Plains Site: Design and surface installation

    SciTech Connect

    Leifer, R.; Knuth, R.H.; Guggenheim, S.F.; Albert, B.

    1996-04-01

    To impropve the predictive capabilities of the Atmospheric Radiation Measurements (ARM) program radiation models, measurements of awserosol size distributions, condensation particle concentrations, aerosol scattering coefficients at a number of wavelenghts, and the aerosol absorption coefficients are needed at the Southern Great Plains (SGP) site. Alos, continuous measurements of ozone concnetrations are needed for model validation. The environmental Measuremenr Laboratory (EMK) has the responsibility to establish the surface aerosol measurements program at the SGP site. EML has designed a special sampling manifold.

  6. Estimating Marine Aerosol Particle Volume and Number from Maritime Aerosol Network Data

    NASA Technical Reports Server (NTRS)

    Sayer, A. M.; Smirnov, A.; Hsu, N. C.; Munchak, L. A.; Holben, B. N.

    2012-01-01

    As well as spectral aerosol optical depth (AOD), aerosol composition and concentration (number, volume, or mass) are of interest for a variety of applications. However, remote sensing of these quantities is more difficult than for AOD, as it is more sensitive to assumptions relating to aerosol composition. This study uses spectral AOD measured on Maritime Aerosol Network (MAN) cruises, with the additional constraint of a microphysical model for unpolluted maritime aerosol based on analysis of Aerosol Robotic Network (AERONET) inversions, to estimate these quantities over open ocean. When the MAN data are subset to those likely to be comprised of maritime aerosol, number and volume concentrations obtained are physically reasonable. Attempts to estimate surface concentration from columnar abundance, however, are shown to be limited by uncertainties in vertical distribution. Columnar AOD at 550 nm and aerosol number for unpolluted maritime cases are also compared with Moderate Resolution Imaging Spectroradiometer (MODIS) data, for both the present Collection 5.1 and forthcoming Collection 6. MODIS provides a best-fitting retrieval solution, as well as the average for several different solutions, with different aerosol microphysical models. The average solution MODIS dataset agrees more closely with MAN than the best solution dataset. Terra tends to retrieve lower aerosol number than MAN, and Aqua higher, linked with differences in the aerosol models commonly chosen. Collection 6 AOD is likely to agree more closely with MAN over open ocean than Collection 5.1. In situations where spectral AOD is measured accurately, and aerosol microphysical properties are reasonably well-constrained, estimates of aerosol number and volume using MAN or similar data would provide for a greater variety of potential comparisons with aerosol properties derived from satellite or chemistry transport model data.

  7. Retrievals of Aerosol and Cloud Particle Microphysics Using Polarization and Depolarization Techniques

    NASA Technical Reports Server (NTRS)

    Mishchenko, Michael; Hansen, James E. (Technical Monitor)

    2001-01-01

    The recent availability of theoretical techniques for computing single and multiple scattering of light by realistic polydispersions of spherical and nonspherical particles and the strong dependence of the Stokes scattering matrix on particle size, shape, and refractive index make polarization and depolarization measurements a powerful particle characterization tool. In this presentation I will describe recent applications of photopolarimetric and lidar depolarization measurements to remote sensing characterization of tropospheric aerosols, polar stratospheric clouds (PSCs), and contrails. The talk will include (1) a short theoretical overview of the effects of particle microphysics on particle single-scattering characteristics; (2) the use of multi-angle multi-spectral photopolarimetry to retrieve the optical thickness, size distribution, refractive index, and number concentration of tropospheric aerosols over the ocean surface; and (3) the application of the T-matrix method to constraining the PSC and contrail particle microphysics using multi-spectral measurements of lidar backscatter and depolarization.

  8. Retrievals of Aerosol and Cloud Particle Microphysics Using Polarization and Depolarization Techniques

    NASA Technical Reports Server (NTRS)

    Mishchenko, Michael; Hansen, James E. (Technical Monitor)

    2001-01-01

    The recent availability of theoretical techniques for computing single and multiple scattering of light by realistic polydispersions of spherical and nonspherical particles and the strong dependence of the Stokes scattering matrix on particle size, shape, and refractive index make polarization and depolarization measurements a powerful particle characterization tool. In this presentation I will describe recent applications of photopolarimetric and lidar depolarization measurements to remote sensing characterization of tropospheric aerosols, polar stratospheric clouds (PSCs), and contrails. The talk will include (1) a short theoretical overview of the effects of particle microphysics on particle single-scattering characteristics; (2) the use of multi-angle multi-spectral photopolarimetry to retrieve the optical thickness, size distribution, refractive index, and number concentration of tropospheric aerosols over the ocean surface; and (3) the application of the T-matrix method to constraining the PSC and contrail particle microphysics using multi-spectral measurements of lidar backscatter and depolarization.

  9. New aerosol particles formation in the Sao Paulo Metropolitan Area

    NASA Astrophysics Data System (ADS)

    Vela, Angel; Andrade, Maria de Fatima; Ynoue, Rita

    2016-04-01

    The Sao Paulo Metropolitan Area (SPMA), in the southeast region of Brazil, is considered a megalopolis comprised of Sao Paulo city and more 38 municipalities. The air pollutant emissions in the SPMA are related to the burning of the fuels: etanol, gasohol (gasoline with 25% ethanol) and diesel. According to CETESB (2013), the road vehicles contributed up to about 97, 87, and 80% of CO, VOCs and NOx emissions in 2012, respectively, being most of NOx associated to diesel combustion and most of CO and VOCs from gasohol and ethanol combustion. Studies conducted on ambient air pollution in the SPMA have shown that black carbon (BC) explains 21% of mass concentration of PM2.5 compared with 40% of organic carbon (OC), 20% of sulfates, and 12% of soil dust (Andrade et al., 2012). Most of the observed ambient PM2.5 mass concentration usually originates from precursors gases such as sulphur dioxide (SO2), ammonia (NH3), nitrogen oxides (NOx) and VOCs as well as through the physico-chemical processes such as the oxidation of low volatile hydrocarbons transferring to the condensed phase (McMurry et al., 2004). The Weather Research and Forecasting with Chemistry model (WRF-Chem; Grell et al. 2005), configured with three nested grid cells: 75, 15, and 3 km, is used as photochemical modeling to describe the physico-chemical processes leading to evolution of particles number and mass size distribution from a vehicular emission model developed by the IAG-USP laboratory of Atmospheric Processes and based on statistical information of vehicular activity. The spatial and temporal distributions of emissions in the finest grid cell are based on road density products compiled by the OpenStreetMap project and measurements performed inside tunnels in the SPMA, respectively. WRF-Chem simulation with coupled primary aerosol (dust and sea-salt) and biogenic emission modules and aerosol radiative effects turned on is conducted as the baseline simulation (Case_0) to evaluate the model

  10. Aerosols, light, and water: Measurements of aerosol optical properties at different relative humidities

    NASA Astrophysics Data System (ADS)

    Orozco, Daniel

    The Earth's atmosphere is composed of a large number of different gases as well as tiny suspended particles, both in solid and liquid state. These tiny particles, called atmospheric aerosols, have an immense impact on our health and on our global climate. Atmospheric aerosols influence the Earth's radiation budget both directly and indirectly. In the direct effect, aerosols scatter and absorb sunlight changing the radiative balance of the Earth-atmosphere system. Aerosols indirectly influence the Earth's radiation budget by modifying the microphysical and radiative properties of clouds as well as their water content and lifetime. In ambient conditions, aerosol particles experience hygroscopic growth due to the influence of relative humidity (RH), scattering more light than when the particles are dry. The quantitative knowledge of the RH effect and its influence on the light scattering coefficient and, in particular, on the phase function and polarization of aerosol particles is of substantial importance when comparing ground based observations with other optical aerosol measurements techniques such satellite and sunphotometric retrievals of aerosol optical depth and their inversions. This dissertation presents the aerosol hygroscopicity experiment investigated using a novel dryer-humidifier system, coupled to a TSI-3563 nephelometer, to obtain the light scattering coefficient (sp) as a function of relative humidity (RH) in hydration and dehydration modes. The measurements were performed in Porterville, CA (Jan 10-Feb 6, 2013), Baltimore, MD (Jul 3-30, 2013), and Golden, CO (Jul 12-Aug 10, 2014). Observations in Porterville and Golden were part of the NASA-sponsored DISCOVER-AQ project. The measured sp under varying RH in the three sites was combined with ground aerosol extinction, PM2:5mass concentrations, particle composition measurements, and compared with airborne observations performed during campaigns. The enhancement factor, f(RH), defined as the ratio of sp

  11. Lidar measurements of forest fire smoke and stratospheric aerosol

    NASA Astrophysics Data System (ADS)

    Aggarwal, Monika

    Lidar measurements of atmospheric aerosols were conducted during two airborne campaigns; Montana in 2007 and the Arctic in 2009. The principle goal of this was to establish whether pyro-convection is a source of stratospheric aerosol. Layers of material were observed downwind of forest fires in the 11 km to 15 km height range during August 2009. The analysis consists of isentropic back trajectory calculations from the Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model which traces the path of stratospheric aerosol layers over forest fires. Satellite imagery was used to determine the altitude of convection in the vicinity of the fires. The depolarization ratio in the lidar backscatter signal was determined in smoke within the troposphere and also within the stratospheric aerosol layers. The smoke had a depolarization ratio of 5.41% +/- 0.04% while the stratospheric aerosol layers had depolarization ratios ranging from 0.20% +/- 0.01% to 1.80% +/- 0.03%. It was concluded that the stratospheric aerosol layers did not originate from fires. As a result, the evidence favours the eruption of Sarychev volcano in mid-June of 2009 as the likely source of stratospheric aerosols observed in Northern Canada.

  12. In Situ Measurement of Aerosol Extinction

    NASA Technical Reports Server (NTRS)

    Strawa, Anthony W.; Castaneda, R.; Owano, T. G.; Bear, D.; Gore, Warren J. (Technical Monitor)

    2001-01-01

    Aerosols are important contributors to the radiative forcing in the atmosphere. Much of the uncertainty in our knowledge of climate forcing is due to uncertainties in the radiative forcing due to aerosols as illustrated in the IPCC reports of the last ten years. Improved measurement of aerosol optical properties, therefore, is critical to an improved understanding of atmospheric radiative forcing. Additionally, attempts to reconcile in situ and remote measurements of aerosol radiative properties have generally not been successful. This is due in part to the fact that it has been impossible to measure aerosol extinction in situ in the past. In this presentation we introduce a new instrument that employs the techniques used in cavity ringdown spectroscopy to measure the aerosol extinction and scattering coefficients in situ. A prototype instrument has been designed and tested in the lab and the field. It is capable of measuring aerosol extinction coefficient to 2x10(exp -6) per meter. This prototype instrument is described and results are presented.

  13. Variation in penetration of submicrometric particles through electrostatic filtering facepieces during exposure to paraffin oil aerosol.

    PubMed

    Plebani, Carmela; Listrani, Stefano; Tranfo, Giovanna; Tombolini, Francesca

    2012-01-01

    Several studies show the increase of penetration through electrostatic filters during exposure to an aerosol flow, because of particle deposition on filter fibers. We studied the effect of increasing loads of paraffin oil aerosol on the penetration of selected particle sizes through an electrostatic filtering facepiece. FFP2 facepieces were exposed for 8 hr to a flow rate of 95.0 ± 0.5 L/min of polydisperse paraffin aerosol at 20.0 ± 0.5 mg/m(3). The penetration of bis(2-ethylhexyl)sebacate (DEHS) monodisperse neutralized aerosols, with selected particle size in the 0.03-0.40 μm range, was measured immediately prior to the start of the paraffin aerosol loading and at 1, 4, and 8 hr after the start of paraffin aerosol loading. Penetration through isopropanol-treated facepieces not oil paraffin loaded was also measured to evaluate facepiece behavior when electrostatic capture mechanisms are practically absent. During exposure to paraffin aerosol, DEHS penetration gradually increased for all aerosol sizes, and the most penetrating particle size (0.05 μm at the beginning of exposure) shifted slightly to larger diameters. After the isopropanol treatment, the higher penetration value was 0.30 μm. In addition to an increased penetration during paraffin loading at a given particle size, the relative degree of increase was greater as the particle size increased. Penetration value measured after 8 hr for 0.03-μm particles was on average 1.6 times the initial value, whereas it was about 8 times for 0.40-μm particles. This behavior, as well evidenced in the measurements of isopropanol-treated facepieces, can be attributed to the increasing action in particle capture of the electrostatic forces (Coulomb and polarization), which depend strictly on the diameter and electrical charge of neutralized aerosol particles. With reference to electrostatic filtering facepieces as personal protective equipment, results suggest the importance of complying with the manufacturer

  14. Aerosol Formation In The Free Troposphere: Aircraft and Laboratory Measurements of Ionic and Gaseous Aerosol Precursors

    NASA Astrophysics Data System (ADS)

    Arnold, F.

    Aerosol formation seems to be very efficient in the upper troposphere (UT) as in- dicated by the frequent presence of numerous very small and therefore very young aerosol particles. Aersosol formation proceeds via nucleation of supersaturated low volatility trace gases (LVG) involving either a homogeneous (HONU) or an ion- induced (INU) mechanism. LVG experience rapid removal by condenstation on prefer- ably pre-existing aerosol particles and therefore LVG must be formed locally in the UT by photochemical conversion of precursor gases. A prominent example is gaseous sulfuric acid which is formed from SO2. This SO2 originates at least in the northern hemisphere mostly from fossil fuel combustion at ground-level and to some part origi- nates also from jet aircraft cruising in the UT. Other conceivable LVG's are low volatil- ity organic compounds. After formation by nucleation new particles may experience condensational growth involving LVG. Alternatively new particles may experience scavenging by attachment to pre-existing larger particles. The LVG-concentration has a strong influence on the growth-rate of new particles and thereby on the possibil- ity for growth to the size of a cloud condensation nucleus. Unfortunately present knowledge on free tropospheric LVG is rather poor. Here will be reported free tropo- spheric aircraft-based measurements of ionic and gaseous aerosol-precursors. These include both measurements in the "background" FT as well as measurements in ex- haust plumes of jet aircraft cruising in the UT. Furthermore accompanying new labo- ratory investigations of INU and measurements behind aircraft jet engines at ground- level will also be adressed.

  15. 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.

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

    DOEpatents

    Novick, Vincent J.

    1998-01-01

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

  17. Measurement of the emission rate of an aerosol source--comparison of aerosol and gas transport coefficients.

    PubMed

    Bémer, D; Callé, S; Godinot, S; Régnier, R; Dessagne, J M

    2000-12-01

    A measuring method of the emission rate of an atmospheric pollutant source, based on the use of a tracer gas (helium) and developed in the case of a gaseous source, was tested for an aerosol source. The influence of both particle sedimentation and wall depositions was studied. The transport coefficients of the tracer gas and of alumina particles of various particle sizes (MMAD from 8 to 36 microns) were measured on a vertical axis close to the source, in a 71 m3 room swept by a piston flow. The measurements clearly demonstrated the predominant influence of sedimentation in the case of particles with aerodynamic diameters greater than 10 microns. Particle wall deposition was determined by measuring the gas and particle concentration decay in the ventilated room. To do this, a new tracing method using a fluorescent aerosol was developed. The measured aerosol deposition rates are much higher than those calculated from the formula of Corner for a cubical volume. Aerosol sedimentation and wall deposition are two phenomena limiting the use of a tracer gas to measure the aerosol emission rate. The chemical substances and materials used in work premises are likely to be released into the atmosphere and lead to the formation of pollutants. These emissions stem from either physical or chemical processes (evaporation of a solvent) or from mechanical processes (dispersion of oil droplets at the source of mists).

  18. Long-term aerosol and trace gas measurements in Eastern Lapland, Finland: the impact of Kola air pollution to new particle formation and potential CCN

    NASA Astrophysics Data System (ADS)

    Kyrö, Ella-Maria; Väänänen, Riikka; Kerminen, Veli-Matti; Virkkula, Aki; Asmi, Ari; Nieminen, Tuomo; Dal Maso, Miikka; Petäjä, Tuukka; Keronen, Petri; Aalto, Pasi; Riipinen, Ilona; Lehtipalo, Katrianne; Hari, Pertti; Kulmala, Markku

    2014-05-01

    Sulphur and primary emissions have been decreasing largely all over Europe, resulting in improved air quality and decreased direct radiation forcing by aerosols. The smelter industry in Kola Peninsula is one of largest sources of anthropogenic SO2 within the Arctic domain and since late 1990s the sulphur emissions have been decreasing rapidly (Paatero et al., 2008; Prank et al., 2010). New particle formation (NPF) is tightly linked with the oxidizing product of SO2, namely sulphuric acid (H2SO4), since it is known to be the key component in atmospheric nucleation (Sipilä et al., 2010). Thus, decreasing sulphur pollution may lead to less NPF. However, low values of condensation sink (CS), which is determined by the amount of pre-existing particles, favours NPF. We used 14 years (1998-2011) of aerosol number size distribution and trace gas data from SMEAR I station in Eastern Lapland, Finland, to investigate these relationships between SO2, NPF and CS. The station is a clean background station with occasional sulphur pollution episodes when the air masses arrive over Kola Peninsula. We found that while SO2 decreased by 11.3 % / year, the number of clear NPF event days was also decreasing by 9.9 % / year. At the same time, CS was decreasing also (-8.0 % / year) leading to formation of more particles per single NPF event (J3 increased by 29.7 % / year in 2006-2011) but the low vapour concentrations of H2SO4 (proxy decreased by 6.2 % / year) did not allow them to grow into climatically relevant sizes. Over the time, concentrations of potential CCN (cloud condensing nuclei) were also decreasing with more moderate pace, -4.0 % / year. The events started on average earlier after sunrise when the SO2 concentration during the start of the event was higher and NPF occurred more frequently in air masses which were travelling over Kola. Despite the total decrease in sulphur pollution originating from Kola there is currently no evidence of cleaning of the emissions, rather the

  19. Eddy Covariance Measurements of the Sea-Spray Aerosol Flu

    NASA Astrophysics Data System (ADS)

    Brooks, I. M.; Norris, S. J.; Yelland, M. J.; Pascal, R. W.; Prytherch, J.

    2015-12-01

    Historically, almost all estimates of the sea-spray aerosol source flux have been inferred through various indirect methods. Direct estimates via eddy covariance have been attempted by only a handful of studies, most of which measured only the total number flux, or achieved rather coarse size segregation. Applying eddy covariance to the measurement of sea-spray fluxes is challenging: most instrumentation must be located in a laboratory space requiring long sample lines to an inlet collocated with a sonic anemometer; however, larger particles are easily lost to the walls of the sample line. Marine particle concentrations are generally low, requiring a high sample volume to achieve adequate statistics. The highly hygroscopic nature of sea salt means particles change size rapidly with fluctuations in relative humidity; this introduces an apparent bias in flux measurements if particles are sized at ambient humidity. The Compact Lightweight Aerosol Spectrometer Probe (CLASP) was developed specifically to make high rate measurements of aerosol size distributions for use in eddy covariance measurements, and the instrument and data processing and analysis techniques have been refined over the course of several projects. Here we will review some of the issues and limitations related to making eddy covariance measurements of the sea spray source flux over the open ocean, summarise some key results from the last decade, and present new results from a 3-year long ship-based measurement campaign as part of the WAGES project. Finally we will consider requirements for future progress.

  20. Complete chemical analysis of aerosol particles in real-time

    SciTech Connect

    Yang, Mo; Reilly, P.T.A.; Gieray, R.A.; Whitten, W.B.; Ramsey, J.M.

    1996-12-31

    Real-time mass spectrometry of individual aerosol particles using an ion trap mass spectrometer is described. The microparticles are sampled directly from the air by a particle inlet system into the vacuum chamber. An incoming particle is detected as it passes through two CW laser beams and a pulsed laser is triggered to intercept the particle for laser ablation ionization at the center of the ion trap. The produced ions are analyzed by the ion trap mass spectrometer. Ions of interest are selected and dissociated through collision with buffer gas atoms for further fragmentation analysis. Real-time chemical analyses of inorganic, organic, and bacterial aerosol articles have been demonstrated. It has been confirmed that the velocity and the size of the incoming particles highly correlate to each other. The performance of the inlet system, particle detection, and preliminary results are discussed.

  1. A bio-aerosol detection technique based on tryptophan intrinsic fluorescence measurement

    NASA Astrophysics Data System (ADS)

    Cai, Shuyao; Zhang, Pei; Zhu, Linglin; Zhao, Yongkai; Huang, Huijie

    2011-12-01

    Based on the measurement of intrinsic fluorescence, a set of bio-aerosol including virus aerosols detection instrument is developed, with which a method of calibration is proposed using tryptophan as the target. The experimental results show a good linear relationship between the fluorescence voltage of the instrument and the concentration of the tryptophan aerosol. An excellent correlation (R2>=0.99) with the sensitivity of 4000PPL is obtained. The research demonstrates the reliability of the bio-aerosol detection by measuring the content of tryptophan. Further more the feasibility of prejudgment to the species of bio-aerosol particles with the multi-channel fluorescence detection technology is discussed.

  2. Digital holography for observing aerosol particles undergoing Brownian motion in microgravity conditions

    NASA Astrophysics Data System (ADS)

    Prodi, F.; Santachiara, G.; Travaini, S.; Belosi, F.; Vedernikov, A.; Dubois, F.; Queeckers, P.; Legros, J. C.

    2006-11-01

    Brownian diffusion of aerosol particles was studied in microgravity conditions using a digital holographic velocimeter. Based on digital image processing, the observed volume, recorded on a charge-coupled device (CCD) camera, is reconstructed slice by slice in order to achieve a full focused volume. Three dimensional coordinates of the particles are retrieved by such procedures and particle trajectories are reconstructed by analysing the sequence of the particle position. We deduced that the displacement of particles in microgravity, due to Brownian motion, follows a Gaussian distribution, like at 1 g. Particle sizes obtained from SEM measurements were in good agreement with those calculated from the three dimensional trajectories provided by the holographic microscope.

  3. Differentiation of primary biological aerosol from mineral dust using single particle mass spectrometry

    NASA Astrophysics Data System (ADS)

    Zawadowicz, M. A.; Froyd, K. D.; Perring, A. E.; Murphy, D. M.; Moehler, O.; Cziczo, D. J.

    2016-12-01

    The role of primary biological aerosol in cloud formation is uncertain. Measurements of biological aerosol abundance, especially at altitudes relevant to cirrus clouds, are scarce. Evidence of biological ice nucleation comes primarily from laboratory ice chamber studies using a limited number of highly-active species. Previous airborne single particle mass spectrometry studies have identified biological particles in ice cloud residuals. However, the methods from those studies have not been shown capable of differentiating biological aerosol from mineral dust. We have developed a robust method of differentiation using aerosol chemistry data collected by the Particle Analysis by Laser Mass Spectrometry (PALMS) instrument by forming a database of atmospherically-relevant PALMS spectra from these aerosol types. We show that mineral dust is often confused with biological material and offer insights as to the reason for confusion. We further use PALMS flight deployments to estimate concentrations of biological aerosol both close to the surface and in the upper troposphere. This method is compared to established techniques of bioaerosol identification, such as Wideband Integrated Bioaerosol Sensor (WIBS) and electron microscopy. The results of this study support mineral dust to be the primary source of ice nucleating particles in the free troposphere.

  4. Retrieval of Aerosol Properties from Multi-Spectral Extinction Measurements

    NASA Technical Reports Server (NTRS)

    Lacis, Andrew A.

    1999-01-01

    The direct-beam spectral extinction of solar radiation contains information on atmospheric composition in a form that is essentially free from the data analysis complexities that often arise from multiple scattering. Ground based Multi-Filter Shadowband Radiometer (MFRSR) measurements provide such information for the vertical atmospheric column path, while solar occultation measurements from a satellite platform provide horizontal slices through the atmosphere. We describe application of a Multi-Spectral Atmospheric Column Extinction (MACE) analysis technique used to analyze MFRSR data also to occultation measurements made by SAGE 11. For analysis, we select the 1985 Nevado del Ruiz volcanic eruption period to retrieve atmospheric profiles of ozone and NO2, and changes in the stratospheric aerosol size and optical depth. The time evolution of volcanic aerosol serves as a passive tracer to study stratospheric dynamics, and changes in particle size put constraints on the sulfur chemistry modeling of volcanic aerosols.

  5. Tandem configuration of differential mobility and centrifugal particle mass analysers for investigating aerosol hygroscopic properties

    NASA Astrophysics Data System (ADS)

    Vlasenko, Sergey S.; Su, Hang; Pöschl, Ulrich; Andreae, Meinrat O.; Mikhailov, Eugene F.

    2017-03-01

    A tandem arrangement of Differential Mobility Analyser and Humidified Centrifugal Particle Mass Analyser (DMA-HCPMA) was developed to measure the deliquescence and efflorescence thresholds and the water uptake of submicron particles over the relative humidity (RH) range from 10 to 95 %. The hygroscopic growth curves obtained for ammonium sulfate and sodium chloride test aerosols are consistent with thermodynamic model predictions and literature data. The DMA-HCPMA system was applied to measure the hygroscopic properties of urban aerosol particles, and the kappa mass interaction model (KIM) was used to characterize and parameterize the concentration-dependent water uptake observed in the 50-95 % RH range. For DMA-selected 160 nm dry particles (modal mass of 3.5 fg), we obtained a volume-based hygroscopicity parameter, κv ≈ 0.2, which is consistent with literature data for freshly emitted urban aerosols.Overall, our results show that the DMA-HCPMA system can be used to measure size-resolved mass growth factors of atmospheric aerosol particles upon hydration and dehydration up to 95 % RH. Direct measurements of particle mass avoid the typical complications associated with the commonly used mobility-diameter-based HTDMA technique (mainly due to poorly defined or unknown morphology and density).

  6. How Well Can Aerosol Measurements from the Terra Morning Polar Orbiting Satellite Represent the Daily Aerosol Abundance and Properties?

    NASA Technical Reports Server (NTRS)

    Kaufman, Y. J.; Holben, B. N.; Tanre, D.; Slutzker, I.; Eck, T. F.; Smirnov, A.; Einaudi, Franco (Technical Monitor)

    2000-01-01

    The Terra mission, launched at the dawn of 1999, and Aqua mission to be launched soon, will possess innovative measurements of the aerosol daily spatial distribution, distinguish between dust, smoke and regional pollution and measure aerosol radiative forcing of climate. Their polar orbit gives daily global coverage, however measurements are acquired at specific time of the day. To what degree can present measurements from Terra taken between 10:00 and 11:30 AM local time, represent the daily average aerosol forcing of climate? Here we answer this question using 7 years of data from the distributed ground based 50-70 instrument Aerosol Robotic Network (AERONET) This (AERONET) half a million measurement data set shows that Terra aerosol measurements represent the daily average values within 5%. The excellent representation is found for large dust particles or small aerosol particles from Fires or regional pollution and for any range of the optical thickness, a measure of the amount of aerosol in the atmosphere.

  7. 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.

  8. Biological aerosol detection with combined passive-active infrared measurements

    NASA Astrophysics Data System (ADS)

    Ifarraguerri, Agustin I.; Vanderbeek, Richard G.; Ben-David, Avishai

    2004-12-01

    A data collection experiment was performed in November of 2003 to measure aerosol signatures using multiple sensors, all operating in the long-wave infrared. The purpose of this data collection experiment was to determine whether combining passive hyperspectral and LIDAR measurements can substantially improve biological aerosol detection p