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Sample records for aerosol particles observed

  1. Organic aerosol mixing observed by single-particle mass spectrometry.

    PubMed

    Robinson, Ellis Shipley; Saleh, Rawad; Donahue, Neil M

    2013-12-27

    We present direct measurements of mixing between separately prepared organic aerosol populations in a smog chamber using single-particle mass spectra from the high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS). Docosane and docosane-d46 (22 carbon linear solid alkane) did not show any signs of mixing, but squalane and squalane-d62 (30 carbon branched liquid alkane) mixed on the time scale expected from a condensational-mixing model. Docosane and docosane-d46 were driven to mix when the chamber temperature was elevated above the melting point for docosane. Docosane vapors were shown to mix into squalane-d62, but not the other way around. These results are consistent with low diffusivity in the solid phase of docosane particles. We performed mixing experiments on secondary organic aerosol (SOA) surrogate systems finding that SOA derived from toluene-d8 (a surrogate for anthropogenic SOA (aSOA)) does not mix into squalane (a surrogate for hydrophobic primary organic aerosol (POA)) but does mix into SOA derived from α-pinene (biogenic SOA (bSOA) surrogate). For the aSOA/POA, the volatility of either aerosol does not limit gas-phase diffusion, indicating that the two particle populations do not mix simply because they are immiscible. In the aSOA/bSOA system, the presence of toluene-d8-derived SOA molecules in the α-pinene-derived SOA provides evidence that the diffusion coefficient in α-pinene-derived SOA is high enough for mixing on the time scale of 1 min. The observations from all of these mixing experiments are generally invisible to bulk aerosol composition measurements but are made possible with single-particle composition data. PMID:24131283

  2. 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

  3. 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

  4. 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.

  5. Ozone and secondary aerosol formation — Analysis of particle observations in the 2009 SHARP campaign

    NASA Astrophysics Data System (ADS)

    Cowin, J.; Yu, X.; Laulainen, N.; Iedema, M.; Lefer, B. L.; Anderson, D.; Pernia, D.; Flynn, J. H.

    2010-12-01

    Particulate matters (PM) play important roles in the formation and transformation of ozone. Although photooxidation of volatile organic compounds with respect to ozone formation in the gas phase is well understood, many unknowns still exist in heterogeneous mechanisms that process soot, secondary aerosols (both inorganic and organic), and key radical precursors such as formaldehyde and nitrous acid. Our main objective is to answer two key science questions: 1) will reduction of fine PM reduce ozone formation? 2) What sources of PM are most culpable? Are they from local chemistry or long-range transport? The field data collected in the 2009 Study of Houston Atmospheric Radical Precursors (SHARP) by our group at the Moody Tower consist of 1) real-time photolysis rates of ozone precursors, 2) particle size distributions, 3) organic carbon and elemental carbon, and 4) an archive of single particle samples taken with the Time Resolved Aerosol Collector (TRAC) sampler. The time resolution of the TRAC sampler is 30 minutes for routine measurements, and 15 minutes during some identified “events” (usually in the mid-afternoon) of high ozone and secondary organic or sulfate particle formation. The latter events last typically about an hour. Five ozone exceedance days occurred during the 6 weeks of deployment. Strong correlation between photochemical activities and organic carbon was observed. Initial data analysis indicates that secondary organic aerosol is a major component of the carbonaceous aerosols observed in Houston. Soot, secondary sulfate, seal salt, and mineral dust particles are determined from single particle analysis using scanning electron microscope and transmission electron microcopy coupled with energy dispersive X-ray spectroscopy. Compared with observations in 2000, the mass percentage of organics is higher (60 vs. 30%), and lower for sulfate (20% vs. 32%). On-going data analysis will focus on the composition, sources, and transformation of primary and

  6. Variability of aerosol particle number concentrations observed over the western Pacific in the spring of 2009

    NASA Astrophysics Data System (ADS)

    Takegawa, N.; Moteki, N.; Oshima, N.; Koike, M.; Kita, K.; Shimizu, A.; Sugimoto, N.; Kondo, Y.

    2014-12-01

    Airborne measurements of aerosols were conducted over the western Pacific in the spring of 2009 during the Aerosol Radiative Forcing in East Asia (A-FORCE) aircraft campaign. The A-FORCE flights intensively covered an important vertical-latitudinal range in the outflow region of East Asia (0-9 km altitude; 27°N-38°N). This paper presents the variability of aerosol particle number concentrations obtained by condensation particle counters and a Single-Particle Soot Photometer (SP2), with the focus on those in the free troposphere. The number concentration data include total condensation nuclei with particle diameters (dp) larger than 10 nm (total CN10), PM0.17-CN10 (dp ~10-130 nm), and SP2 black carbon (NBC; dp ~75-850 nm). Large increases in total CN10 that were not associated with NBC were observed in the free troposphere, suggesting influences from new particle formation (NPF). Statistical characteristics of total CN10, PM0.17-CN10, and NBC in the lower troposphere (LT; 0-3 km), middle troposphere (MT; 3-6 km), and upper troposphere (UT; 6-9 km) are investigated. The correlation between total CN10 and NBC, along with the ratio of PM0.17 to total CN10 and carbon monoxide mixing ratio (CO), is used to interpret the observed variability. The median concentrations of total CN10 and PM0.17-CN10 in the UT were higher than those in the MT by a factor of ~1.4 and ~1.6, respectively. We attribute the enhancements of CN10 in the UT to NPF. Possible mechanisms affecting NPF in the free troposphere are discussed.

  7. Field Observations of the Processing of Organic Aerosol Particles and Trace Gases by Fogs and Clouds

    NASA Astrophysics Data System (ADS)

    Collett, J. L.; Herckes, P.

    2003-12-01

    In many environments, organic compounds account for a significant fraction of fine particle mass. Because the lifetimes of accumulation mode aerosol particles are governed largely by interactions with clouds, it is important to understand how organic aerosol particles are processed by clouds and fogs. Recently we have examined the organic composition of clouds and fogs in a variety of environments as well as how these fogs and clouds process organic aerosol particles and soluble organic trace gases. The investigations, conducted in Europe, North America, Central America, and the Pacific region, have included studies of polluted radiation fogs, orographic clouds in clean and polluted environments, and marine stratocumulus. Our results show that organic matter is a significant component of fog and cloud droplets. In polluted California radiation fogs, we observed concentrations of total organic carbon (TOC) ranging from 2 to 40 ppmC, with significantly lower concentrations measured in marine and continental clouds. An average of approximately 80 percent of organic matter was found in solution, while the remainder appears to be suspended material inside cloud and fog drops. Ultrafiltration measurements indicate that as much as half of the dissolved organic carbon is present in very large molecules with molecular weights in excess of 500 Daltons. Field measurements made using a two-stage cloud water collector reveal that organic matter tends to be enriched in smaller cloud or fog droplets. Consequently, removal of organic compounds by precipitating clouds or by direct cloud/fog drop deposition will be slowed due to the fact that small drops are incorporated less efficiently into precipitation and removed less efficiently by sedimentation or inertial impaction. Despite this trend, we have observed that sedimentation of droplets from long-lived radiation fogs provides a very effective mechanism for cleansing the atmosphere of carbonaceous aerosol particles, with organic

  8. Direct observation of aerosol particles in aged agricultural biomass burning plumes impacting urban atmospheres

    NASA Astrophysics Data System (ADS)

    Li, W. Y.; Shao, L. Y.

    2010-04-01

    Emissions from agricultural biomass burning (ABB) in northern China have a significant impact on the regional and the global climate. According to the Giovanni's Aerosol optical depth (AOD) map, the monthly average AOD at 550 nm in northern China in 2007 shows a maximum value of 0.7 in June, suggesting that episodes of severe aerosol pollution occurred in this region. Aerosol particles were collected in urban Beijing during regional brown hazes from 12 to 30 June, 2007. Transmission electron microscopy with energy-dispersive X-ray spectrometry characterized the morphology, composition, and mixing state of aerosol particles. Potassium salts (K2SO4 and KNO3), ammonium sulfate, soot, and organic particles predominated in fine particles (diameter <1 μm) collected from 12 to 20 June, 2007. In contrast, from 21 to 30 June, 2007, ammonium sulfate, soot, and organic particles were dominant. Potassium-dominant particles as a tracer of biomass burning, together with wildfire maps, show that intensive regional ABB in northern China from 10 to 20 June, 2007 contributed significantly to the regional haze. After long-range transport, ABB particles exhibited marked changes in their morphology, elemental composition, and mixing state. Heterogeneous reactions completely converted KCl particles from ABB into K2SO4 and KNO3. Soot particles were generally mixed with potassium salts, ammonium salts, and organic particles. In addition, the abundant aged organic particles and soluble salts emitted by ABB become more hygroscopic and increase their size during long-range transport, becoming in effect additional cloud condensation nuclei. The high AOD (average value at 2.2) during 12 to 20 June, 2007, in Beijing is partly explained by the hygroscopic growth of aged fine aerosol particles and by the strong absorption of internally mixed soot particles, both coming from regional ABB emissions.

  9. Observations of Sub-3 nm Particles and Sulfuric acid Concentrations during Aerosol Life Cycle Intensive Observation Period 2011 in Long Island, New York

    NASA Astrophysics Data System (ADS)

    Yu, H.; Kanawade, V. P.; You, Y.; Hallar, A. G.; Mccubbin, I. B.; Chirokova, G.; Sedlacek, A. J.; Springston, S. R.; Wang, J.; Kuang, C.; Lee, Y.; McGraw, R. L.; Mikkila, J.; Lee, S.

    2012-12-01

    Atmospheric new particle formation (NPF) is an important source of aerosol particles. But the NPF processes are not well understood, in part because of our limited understanding of the formation of atmospheric sub-3 nm size aerosols and the limited number of simultaneous observations of particle size distributions and the aerosol nucleation precursors. During Aerosol Life Cycle Intensive Observation Period (July-August 2011) in Long Island, New York, we deployed a particle size magnifier (Airmodus A09) running at different working fluid saturation ratios and a TSI CPC3776 to extract the information of sub-3 nm particles formation. A scanning mobility particle spectrometer (SMPS), a chemical ionization mass spectrometer (CIMS), and a number of atmospheric trace gas analyzers were used to simultaneously measure aerosol size distributions, sulfuric acid, and other possible aerosol precursors, respectively. Our observation results show that sub-3 nm particles existed during both NPF and non-NPF events, indicating the formation of sub-3nm particle didn't always lead to NPF characterized by typical banana shaped aerosol size distributions measured by SMPS. However, sub-3 nm particles were much higher during NPF events. Sub-3 nm particles were well-correlated with sulfuric acid showing the same diurnal variations and noontime peaks, especially for NPF days. These results are consistent with laboratory studies showing that formation of sub-3 nm particles is very sensitive to sulfuric acid (than amines and ammonia) [Yu et al. GRL 2012]. HYSPLIT back trajectory analysis indicates that air masses from Great Lakes, containing more SO2, VOCs and secondary organics, may contribute to growth of sub-3 nm particles and NPF.

  10. Aerosol and Cloud-Nucleating Particle Observations during an Atmospheric River Event

    NASA Astrophysics Data System (ADS)

    DeMott, P. J.; McCluskey, C. S.; Petters, M.; Suski, K. J.; Levin, E. J.; Hill, T. C. J.; Atwood, S. A.; Schill, G. P.; Rocci, K.; Boose, Y.; Martin, A.; Cornwell, G.; Al-Mashat, H.; Moore, K.; Prather, K. A.; Rothfuss, N.; Taylor, H.; Leung, L. R.; Tomlinson, J. M.; Mei, F.; Hubbe, J. M.; Rosenfeld, D.; Spackman, J. R.; Fairall, C. W.; Creamean, J.; White, A. B.; Kreidenweis, S. M.

    2015-12-01

    The multi-agency CalWater 2015 project occurred over North Central CA and the Eastern Pacific during January to March 2015 (Spackman et al., this session). The goals of the campaign were to document the structure of atmospheric rivers (ARs) that deliver much of the water vapor associated with major winter storms along the U.S. West Coast and to investigate the modulating effect of aerosols on precipitation. Aerosol sources that may influence orographic cloud properties for air lifted over the mountains in California in winter include pollution, biomass burning, soil dusts and marine aerosols, but their roles will also be influenced by transport, vertical stratification, and scavenging processes. We present results from a comprehensive study of aerosol distributions, compositions, and cloud nucleating properties during an intense winter storm during February 2015, including data from an NSF-supported measurement site at Bodega Bay, from the DOE-ARM Cloud Aerosol Precipitation Experiment that included sampling on the NOAA RV Ron Brown offshore and the G-1 aircraft over ocean and land, and with context provided by other NOAA aircraft and remote sensing facilities. With a special focus on the coastal site, we discuss changes in aerosol distributions, aerosol hygroscopicity, and number concentrations of fluorescent particles, cloud condensation nuclei (CCN), and ice nucleating particles (INPs) during the AR event. We compare with periods preceding and following the event. For example, total aerosol number and surface area concentrations at below 0.5 μm diameter decreased from typical values of a few thousand cm-3 and 100 μm2 cm-3, respectively, to a few hundred cm-3 and 10 μm2cm-3 at Bodega Bay during the AR event. CCN concentrations were similarly lower, but hygroscopicity parameter (kappa) increased from typical values of 0.2 to values > 0.5 during the AR.INP and fluorescent particle number concentrations were generally lower during the AR event than at any other

  11. Aerosol particle properties in the tropical free troposphere observed at Pico Espejo (4765 m a.s.l.), Venezuela

    NASA Astrophysics Data System (ADS)

    Schmeißner, T.; Krejci, R.; Ström, J.; Birmili, W.; Wiedensohler, A.; Hochschild, G.; Gross, J.; Hoffmann, P.; Calderon, S.

    2010-11-01

    The first long-term measurements of aerosol number and size distributions in South-American tropical free troposphere were performed from March 2007 until Mai 2009. The measurements took place at the high altitude Atmospheric Research Station Alexander von Humboldt. The station is located on top of the Sierra Nevada mountain ridge at 4765 m a.s.l. nearby the city of Mérida, Venezuela. Aerosol size distribution and number concentration data was obtained with a custom-built Differential Mobility Particle Sizer (DMPS system) and a Condensational Particle Counter (CPC). The analysis of the annual and diurnal variability of the tropical free troposphere (FT) aerosol focused mainly on possible links to the atmospheric general circulation in the tropics. Considerable annual and diurnal cycles of the particle number concentration were observed. Highest total particle number concentrations were measured during the dry season (519±613 cm-3), lowest during the wet season (318±194 cm-3). The more humid FT contained generally higher aerosol particle number concentrations (573±768 cm-3 during dry season, 320±195 cm-3 during wet season) than the dry FT (454±332 cm-3 during dry season, 275±172 cm-3 during wet season), indicating the importance of convection for aerosol distributions in the tropical FT. The diurnal cycle in the variability of the particle number concentration was mainly driven by local orography.

  12. Comparison of Satellite Observations of Aerosol Optical Depth to Surface Monitor Fine Particle Concentration

    NASA Technical Reports Server (NTRS)

    Kleb, Mary M.; AlSaadi, Jassim A.; Neil, Doreen O.; Pierce, Robert B.; Pippin, Margartet R.; Roell, Marilee M.; Kittaka, Chieko; Szykman, James J.

    2004-01-01

    Under NASA's Earth Science Applications Program, the Infusing satellite Data into Environmental Applications (IDEA) project examined the relationship between satellite observations and surface monitors of air pollutants to facilitate a more capable and integrated observing network. This report provides a comparison of satellite aerosol optical depth to surface monitor fine particle concentration observations for the month of September 2003 at more than 300 individual locations in the continental US. During September 2003, IDEA provided prototype, near real-time data-fusion products to the Environmental Protection Agency (EPA) directed toward improving the accuracy of EPA s next-day Air Quality Index (AQI) forecasts. Researchers from NASA Langley Research Center and EPA used data from the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument combined with EPA ground network data to create a NASA-data-enhanced Forecast Tool. Air quality forecasters used this tool to prepare their forecasts of particle pollution, or particulate matter less than 2.5 microns in diameter (PM2.5), for the next-day AQI. The archived data provide a rich resource for further studies and analysis. The IDEA project uses data sets and models developed for tropospheric chemistry research to assist federal, state, and local agencies in making decisions concerning air quality management to protect public health.

  13. A Year-round Observation of Size Distribution of Aerosol Particles at the Cape Ochiishi, Japan

    NASA Astrophysics Data System (ADS)

    Miura, K.; Mukai, H.; Hashimoto, S.; Uematsu, M.

    2010-12-01

    New particle formation by nucleation of gas-phase compounds emitted from marine biogenic sources is very important for climate change. To clarify the mechanism of the formation, size distributions of submicron aerosols have been measured at the Cape Ochiishi, facing the North Western Pacific Ocean where primary productivity is high. A test observation was done from 22nd May to 18th June 2008 and a year-round observation has been performed from 16th October 2009 to 7th September 2010. The size distribution from 10 nm to 487 nm in diameter was measured with a scanning mobility particle sizer (SMPS, TSI 3034). Sample air was dried to lower than 40%. Transport of sulfate, organic carbon (OC), and black carbon (BC) was estimated with Chemical weather FORecasting System (CFORS), developed by Prof. Uno, Kyushu University, Japan. Existence of inversion layer was estimated with temperature profile measured at surface, 10m, 30m, and 50m in altitude. The burst of the particles smaller than 20nm in diameter continuing longer than 3 hrs was observed ten times until 3rd November 2009. Two were observed in early summer and the other was in autumn. Banana shape was faintly observed five times. Transport of sulfate, OC, and BC was observed 3, 8, 9 times, respectively. Source of air mass was estimated with these elements, weather map, and wind direction. Five air masses were estimated to continental. Clearly nucleation related to marine sources was not observed. The size distribution of burst evens of maritime and continental air mass showed the shift of mode to larger diameter. Strong inversion of temperature was observed once. The value of size distribution did not show high. Minimum value of size distribution was observed in the strong rain on 27th October. Acknowledgments This study was partly supported by the Grant-in-Aids for Scientific Research on Priority Areas from the Ministry of Education, Culture, Sports, Science and Technology, Japan (18067005). The observation was

  14. Retrieving the aerosol particle distribution in Titan's detached layer from ISS limb observations

    NASA Astrophysics Data System (ADS)

    Seignovert, B.; Rannou, P.; Lavvas, P.; Cours, T.; West, R. A.

    2015-10-01

    The study of the detached haze layer above Titan's thick atmosphere is one of the key elements to understand the growth of the aerosols in the upper atmosphere of Titan. In this work we will present the results of a radiative transfer inversion of the vertical profile distribution of aerosols in the detached haze layer (from 300 to 600 km) by using the I/F ratio ob- served by Cassini ISS camera. The analyses will focus on the derivation of the particle size distribution.

  15. Aerosol Observing System (AOS) Handbook

    SciTech Connect

    Jefferson, A

    2011-01-17

    The Aerosol Observing System (AOS) is a suite of in situ surface measurements of aerosol optical and cloud-forming properties. The instruments measure aerosol properties that influence the earth’s radiative balance. The primary optical measurements are those of the aerosol scattering and absorption coefficients as a function of particle size and radiation wavelength and cloud condensation nuclei (CCN) measurements as a function of percent supersaturation. Additional measurements include those of the particle number concentration and scattering hygroscopic growth. Aerosol optical measurements are useful for calculating parameters used in radiative forcing calculations such as the aerosol single-scattering albedo, asymmetry parameter, mass scattering efficiency, and hygroscopic growth. CCN measurements are important in cloud microphysical models to predict droplet formation.

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

    NASA Astrophysics Data System (ADS)

    Jensen, J. B.

    2015-12-01

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

  17. Chemical imaging of ambient aerosol particles: Observational constraints on mixing state parameterization

    NASA Astrophysics Data System (ADS)

    O'Brien, Rachel E.; Wang, Bingbing; Laskin, Alexander; Riemer, Nicole; West, Matthew; Zhang, Qi; Sun, Yele; Yu, Xiao-Ying; Alpert, Peter; Knopf, Daniel A.; Gilles, Mary K.; Moffet, Ryan C.

    2015-09-01

    A new parameterization for quantifying the mixing state of aerosol populations has been applied for the first time to samples of ambient particles analyzed using spectro-microscopy techniques. Scanning transmission X-ray microscopy/near edge X-ray absorption fine structure (STXM/NEXAFS) and computer-controlled scanning electron microscopy/energy dispersive X-ray spectroscopy (CCSEM/EDX) were used to probe the composition of the organic and inorganic fraction of individual particles collected on 27 and 28 June during the 2010 Carbonaceous Aerosols and Radiative Effects study in the Central Valley, California. The first field site, T0, was located in downtown Sacramento, while T1 was located near the Sierra Nevada Mountains. Mass estimates of the aerosol particle components were used to calculate mixing state metrics, such as the particle-specific diversity, bulk population diversity, and mixing state index, for each sample. The STXM data showed evidence of changes in the mixing state associated with a buildup of organic matter confirmed by collocated measurements, and the largest impact on the mixing state was due to an increase in soot dominant particles during this buildup. The mixing state from STXM was similar between T0 and T1, indicating that the increased organic fraction at T1 had a small effect on the mixing state of the population. The CCSEM/EDX analysis showed the presence of two types of particle populations: the first was dominated by aged sea-salt particles and had a higher mixing state index (indicating a more homogeneous population); the second was dominated by carbonaceous particles and had a lower mixing state index.

  18. Chemical Imaging of Ambient Aerosol Particles: Observational Constraints on Mixing State Parameterization

    SciTech Connect

    O'Brien, Rachel; Wang, Bingbing; Laskin, Alexander; Riemer, Nicole; West, Matthew; Zhang, Qi; Sun, Yele; Yu, Xiao-Ying; Alpert, Peter A.; Knopf, Daniel A.; Gilles, Mary K.; Moffet, Ryan

    2015-09-28

    A new parameterization for quantifying the mixing state of aerosol populations has been applied for the first time to samples of ambient particles analyzed using spectro-microscopy techniques. Scanning transmission x-ray microscopy/near edge x-ray absorption fine structure (STXM/NEXAFS) and computer controlled scanning electron microscopy/energy dispersive x-ray spectroscopy (CCSEM/EDX) were used to probe the composition of the organic and inorganic fraction of individual particles collected on June 27th and 28th during the 2010 Carbonaceous Aerosols and Radiative Effects (CARES) study in the Central Valley, California. The first field site, T0, was located in downtown Sacramento, while T1 was located near the Sierra Nevada Mountains. Mass estimates of the aerosol particle components were used to calculate mixing state metrics, such as the particle-specific diversity, bulk population diversity, and mixing state index, for each sample. Both microscopy imaging techniques showed more changes over these two days in the mixing state at the T0 site than at the T1 site. The STXM data showed evidence of changes in the mixing state associated with a build-up of organic matter confirmed by collocated measurements and the largest impact on the mixing state was due to an increase in soot dominant particles during this build-up. The CCSEM/EDX analysis showed the presence of two types of particle populations; the first was dominated by aged sea salt particles and had a higher mixing state index (indicating a more homogeneous population), the second was dominated by carbonaceous particles and had a lower mixing state index.

  19. Mass Spectral Observations of Submicron Aerosol Particles and Production of Secondary Organic Aerosol at an Anthropogenically Influenced Site during the Wet Season of GoAmazon2014

    NASA Astrophysics Data System (ADS)

    de Sá, S. S.; Palm, B. B.; Campuzano Jost, P.; Day, D. A.; Hu, W.; Newburn, M. K.; Ferreira De Brito, J.; Artaxo, P.; Shilling, J. E.; Souza, R. A. F. D.; Manzi, A. O.; Alexander, M. L.; Jimenez, J. L.; Martin, S. T.

    2014-12-01

    As part of GoAmazon2014, a high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) was deployed to characterize the composition, size, and spectral markers present in submicron atmospheric aerosol particles at a site downwind of Manaus, Brazil, in the central Amazon basin. The focus was on the influence of biogenic-anthropogenic interactions on the measured aerosol particles, especially as related to the formation of secondary organic aerosol (SOA). Through a combination of meteorology, emissions, and chemistry, the research site was affected by biogenic emissions from the tropical rainforest that were periodically mixed with urban outflow from the Manaus metropolitan area. Results from the first intensive operation period, from 1 February to 31 March 2014, show that for the wet season the PM1 mass concentration had typical values on order of 1 to 2 μg/m3. The organic species were dominant, followed by sulfate. The mass-diameter distribution of the particle population had a prevailing mode between 300 and 400 nm (vacuum aerodynamic diameter, dva), and at times a smaller mode at finer size was also present. Highly oxidized organic material was frequently observed, characterized by a dominant peak at m/z 44. There was a diel trend in the elemental oxygen-to-carbon (O:C) ratio peaking in the afternoon. The analysis of the results aims at delineating the anthropogenic impact on the measurements. Multivariate statistical analysis by positive-matrix factorization (PMF) is applied to the time series of organic particle mass spectra. The factors and their loadings provide information on the relative and time-varying contributions of different sources and processes affecting the organic component of the aerosol particle phase. Relationships between AMS results and measurements from co-located instruments that provide information on anthropogenic and biogenic gas and particle tracers are investigated, toward the goal of improving the understanding of

  20. Observations of Smoke Aerosol from Biomass Burning in Mexico: Effect of Particle Aging on Radiative Forcing and Remote Sensing

    NASA Technical Reports Server (NTRS)

    Remer, Lorraine A.; Bruintjes, Roelof; Holben, Brent N.; Christopher, Sundar

    1999-01-01

    We take advantage of the May 1998 biomass burning event in Southern Mexico to test the global applicability of a smoke aerosol size model developed from data observed in South America. The Mexican event is an unique opportunity to observe well-aged, residual smoke. Observations of smoke aerosol size distribution made from vertical profiles of airborne in situ measurements show an inverse relationship between concentration and particle size that suggests the aging process continues more than a week after the smoke is separated from its fire sources. The ground-based radiometer retrievals show that the column-averaged, aged, Mexican smoke particles are larger (diameter = 0.28 - 0.33 micrometers) than the mean smoke particles in South America (diameter = 0.22 - 0.30 micrometers). However, the difference (delta - 0.06 micrometer) translates into differences in backscattering coefficient of only 4-7% and an increase of direct radiative forcing of only 10%.

  1. Observing wind, aerosol particles, cloud and precipitation: Finland's new ground-based remote-sensing network

    NASA Astrophysics Data System (ADS)

    Hirsikko, A.; O'Connor, E. J.; Komppula, M.; Korhonen, K.; Pfüller, A.; Giannakaki, E.; Wood, C. R.; Bauer-Pfundstein, M.; Poikonen, A.; Karppinen, T.; Lonka, H.; Kurri, M.; Heinonen, J.; Moisseev, D.; Asmi, E.; Aaltonen, V.; Nordbo, A.; Rodriguez, E.; Lihavainen, H.; Laaksonen, A.; Lehtinen, K. E. J.; Laurila, T.; Petäjä, T.; Kulmala, M.; Viisanen, Y.

    2013-08-01

    The Finnish Meteorological Institute, in collaboration with the University of Helsinki, has established a new ground-based remote-sensing network in Finland. The network consists of five topographically, ecologically and climatically different sites distributed from southern to northern Finland. The main goal of the network is to monitor air pollution and boundary layer properties in near real time, with a Doppler lidar and ceilometer at each site. In addition to these operational tasks, two sites are members of the Aerosols, Clouds, and Trace gases Research InfraStructure Network (ACTRIS); a Ka-band Doppler cloud radar at Sodankylä will provide cloud retrievals within CloudNet, and a multi-wavelength Raman lidar, POLLYXT (POrtabLe Lidar sYstem eXTended), in Kuopio provides optical and microphysical aerosol properties through EARLINET (European Aerosol Research Lidar Network to Establish an Aerosol Climatology). Three C-band weather radars are located in the Helsinki metropolitan area and are deployed for operational and research applications. We carried out two inter-comparison campaigns to investigate the Doppler lidar performance. The aims of the campaigns were to compare the backscatter coefficient and retrieved wind profiles, and to optimise the lidar sensitivity through adjusting the telescope focus and data-integration time to ensure enough signals in low-aerosol-content environments. The wind profiles showed good agreement between different lidars. However, due to inaccurate telescope focus setting and varying receiver sensitivity, backscatter coefficient profiles showed disagreement between the lidars. Harsh Finnish winters could pose problems, but, due to the built-in heating systems, low ambient temperatures had no, or only a minor, impact on the lidar operation: including scanning-head motion. However, accumulation of snow and ice on the lens has been observed, which can lead to formation of a water/ice layer thus attenuating the signal inconsistently

  2. Observations of a bimodal size distribution for the aerosol particles on Mars by SPICAM/MEX

    NASA Astrophysics Data System (ADS)

    Fedorova, A.; Montmessin, F.; Rodin, A.; Korablev, O.; Määttänen, A.; Bertaux, J. L.

    2013-09-01

    We present first results of simultaneous analysis of the ultraviolet (UV) and infrared (IR) atmospheric extinctions obtained by SPICAM on Mars Express by means of solar occultations in the Martian atmosphere in the beginning of the northern summer (Ls=56-97°) at the middle northern and southern latitudes. Based on Mie scattering theory with adequate refraction indices for dust and H2O ice, a bimodal distribution of aerosol has been inferred from the SPICAM measurements at the altitudes from 10 to 50 km. The coarser mode exists for both H2O and dust particles with average radius of 1.3 and 0.7 μm, respectively, with number density from 0.01 to 10 particles to cm3. In addition, a small mode has been detected in both hemispheres with a radius of 0.03-0.07 μm and a number density from 1 cm-3 at 60 km to 1,000 cm-3 at 10-20 km.

  3. Observing wind, aerosol particles, cloud and precipitation: Finland's new ground-based remote-sensing network

    NASA Astrophysics Data System (ADS)

    Hirsikko, A.; O'Connor, E. J.; Komppula, M.; Korhonen, K.; Pfüller, A.; Giannakaki, E.; Wood, C. R.; Bauer-Pfundstein, M.; Poikonen, A.; Karppinen, T.; Lonka, H.; Kurri, M.; Heinonen, J.; Moisseev, D.; Asmi, E.; Aaltonen, V.; Nordbo, A.; Rodriguez, E.; Lihavainen, H.; Laaksonen, A.; Lehtinen, K. E. J.; Laurila, T.; Petäjä, T.; Kulmala, M.; Viisanen, Y.

    2014-05-01

    The Finnish Meteorological Institute, in collaboration with the University of Helsinki, has established a new ground-based remote-sensing network in Finland. The network consists of five topographically, ecologically and climatically different sites distributed from southern to northern Finland. The main goal of the network is to monitor air pollution and boundary layer properties in near real time, with a Doppler lidar and ceilometer at each site. In addition to these operational tasks, two sites are members of the Aerosols, Clouds and Trace gases Research InfraStructure Network (ACTRIS); a Ka band cloud radar at Sodankylä will provide cloud retrievals within CloudNet, and a multi-wavelength Raman lidar, PollyXT (POrtabLe Lidar sYstem eXTended), in Kuopio provides optical and microphysical aerosol properties through EARLINET (the European Aerosol Research Lidar Network). Three C-band weather radars are located in the Helsinki metropolitan area and are deployed for operational and research applications. We performed two inter-comparison campaigns to investigate the Doppler lidar performance, compare the backscatter signal and wind profiles, and to optimize the lidar sensitivity through adjusting the telescope focus length and data-integration time to ensure sufficient signal-to-noise ratio (SNR) in low-aerosol-content environments. In terms of statistical characterization, the wind-profile comparison showed good agreement between different lidars. Initially, there was a discrepancy in the SNR and attenuated backscatter coefficient profiles which arose from an incorrectly reported telescope focus setting from one instrument, together with the need to calibrate. After diagnosing the true telescope focus length, calculating a new attenuated backscatter coefficient profile with the new telescope function and taking into account calibration, the resulting attenuated backscatter profiles all showed good agreement with each other. It was thought that harsh Finnish

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

    NASA Astrophysics Data System (ADS)

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

    2001-11-01

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

  5. Microphysical processes affecting stratospheric aerosol particles

    NASA Technical Reports Server (NTRS)

    Hamill, P.; Toon, O. B.; Kiang, C. S.

    1977-01-01

    Physical processes which affect stratospheric aerosol particles include nucleation, condensation, evaporation, coagulation and sedimentation. Quantitative studies of these mechanisms to determine if they can account for some of the observed properties of the aerosol are carried out. It is shown that the altitude range in which nucleation of sulfuric acid-water solution droplets can take place corresponds to that region of the stratosphere where the aerosol is generally found. Since heterogeneous nucleation is the dominant nucleation mechanism, the stratospheric solution droplets are mainly formed on particles which have been mixed up from the troposphere or injected into the stratosphere by volcanoes or meteorites. Particle growth by heteromolecular condensation can account for the observed increase in mixing ratio of large particles in the stratosphere. Coagulation is important in reducing the number of particles smaller than 0.05 micron radius. Growth by condensation, applied to the mixed nature of the particles, shows that available information is consistent with ammonium sulfate being formed by liquid phase chemical reactions in the aerosol particles. The upper altitude limit of the aerosol layer is probably due to the evaporation of sulfuric acid aerosol particles, while the lower limit is due to mixing across the tropopause.

  6. Preliminary Observations of organic gas-particle partitioning from biomass combustion smoke using an aerosol mass spectrometer

    NASA Astrophysics Data System (ADS)

    Lee, T.; Kreidenweis, S. M.; Collett, J. L.; Sullivan, A. P.; Carrico, C. M.; Jimenez, J. L.; Cubison, M.; Saarikoski, S.; Worsnop, D. R.; Onasch, T. B.; Fortner, E.; Malm, W. C.; Lincoln, E.; Wold, C. E.; Hao, W.

    2010-12-01

    Aerosols play important roles in adverse health effects, indirect and direct forcing of Earth’s climate, and visibility degradation. Biomass burning emissions from wild and prescribed fires can make a significant contribution to ambient aerosol mass in many locations and seasons. In order to better understand the chemical properties of particles produced by combustion of wild land fuels, an experiment was conducted in 2009 at the U.S. Forest Service/United States Department of Agriculture (USFS/USDA) Fire Science Laboratory (FSL) located in Missoula, Montana, to measure volatility of open biomass burning emissions for a variety of fuel types. Both isothermal and temperature-dependent volatilization were studied, using an Aerodyne High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) coupled with thermal denuder. Small quantities (200-800g) of various fuel types, primarily from the U.S., were burned in a large combustion chamber and diluted in two stages in continuous-flow residence chambers. The partitioning of particulate organic mass concentrations by the HR-ToF-AMS was evaluated for each fuel type using nominal dilution ratios characterized both by measuring flow rates in continuous-flow residence chambers and from the concentrations of several conserved tracers. The volatility of biomass burning smoke was found to vary across fuel types. Up to ~60% volatile loss of organic matter was observed as a result of dilution for some smoke samples (e.g., Lodgepole pine and Ponderosa pine). We will investigate relationships between volatility and several parameters such as the absolute mass concentration and chemical composition. We will also examine the behavior of biomass burning tracers, such as AMS m/z 60, under dilution conditions. Previous studies (e.g. Lee et al., AS&T 2010 and Aiken et al., ACP 2009) have observed a strong relationship between OA and AMS m/z 60 in fresh biomass burning smoke. We will examine whether this relationship is altered

  7. Analysis of number size distributions of tropical free tropospheric aerosol particles observed at Pico Espejo (4765 m a.s.l.), Venezuela

    NASA Astrophysics Data System (ADS)

    Schmeissner, T.; Krejci, R.; Ström, J.; Birmili, W.; Wiedensohler, A.; Hochschild, G.; Gross, J.; Hoffmann, P.; Calderon, S.

    2011-04-01

    The first long-term measurements of aerosol number and size distributions in South-American tropical free troposphere (FT) were performed from March 2007 until March 2009. The measurements took place at the high altitude Atmospheric Research Station Alexander von Humboldt. The station is located on top of the Sierra Nevada mountain ridge at 4765 m a.s.l. nearby the city of Mérida, Venezuela. Aerosol size distribution and number concentration data was obtained with a custom-built Differential Mobility Particle Sizer (DMPS) system and a Condensational Particle Counter (CPC). The analysis of the annual and diurnal variability of the tropical FT aerosol focused mainly on possible links to the atmospheric general circulation in the tropics. Considerable annual and diurnal cycles of the particle number concentration were observed. Highest total particle number concentrations were measured during the dry season (January-March, 519 ± 613 cm-3), lowest during the wet season (July-September, 318 ± 194 cm-3). The more humid FT (relative humidity (RH) range 50-95 %) contained generally higher aerosol particle number concentrations (573 ± 768 cm-3 during dry season, 320 ± 195 cm-3 during wet season) than the dry FT (RH < 50 %, 454 ± 332 cm-3 during dry season, 275 ± 172 cm-3 during wet season), indicating the importance of convection for aerosol distributions in the tropical FT. The diurnal cycle in the variability of the particle number concentration was mainly driven by local orography.

  8. Stratospheric aerosols - Observation and theory

    NASA Technical Reports Server (NTRS)

    Turco, R. P.; Whitten, R. C.; Toon, O. B.

    1982-01-01

    Important chemical and physical roles of aerosols are discussed, and properties of stratospheric aerosols as revealed by experimental data are described. In situ measurements obtained by mechanical collection and scattered-light detection yield the overall size distribution of the aerosols, and analyses of preserved aerosol precursor gases by wet chemical, cryogenic and spectroscopic techniques indicate the photochemical sources of particle mass. Aerosol chemical reactions including those of gaseous precursors, those in aqueous solution, and those on particle surfaces are discussed, in addition to aerosol microphysical processes such as nucleation, condensation/evaporation, coagulation and sedimentation. Models of aerosols incorporating such chemical and physical processes are presented, and simulations are shown to agree with measurements. Estimates are presented for the potential aerosol changes due to emission of particles and gases by aerospace operations and industrial consumption of fossil fuels, and it is demonstrated that although the climatic effects of existing levels of stratospheric aerosol pollution are negligible, potential increases in those levels might pose a future threat.

  9. Vertical distribution of non-volatile species of upper tropospheric and lower stratospheric aerosol observed by balloon-borne optical particle counter above Ny-Aalesund, Norway in the winter of 2015

    NASA Astrophysics Data System (ADS)

    Shiraishi, K.; Hayashi, M.; Shibata, T.; Neuber, R.; Ruhe, W.

    2015-12-01

    The polar lower stratosphere is the sink area of stratospheric global circulation. The composition, concentration and size distribution of aerosol in the polar stratosphere are considered to be strongly influenced by the transportations from mid-latitude to polar region and exchange of stratosphere to troposphere. In order to study the aerosol composition and size distribution in the Arctic stratosphere and the relationship between their aerosol microphysical properties and transport process, we carried out balloon-borne measurement of aerosol volatility above Ny-Aalesund, Norway in the winter of 2015. In our observation, two optical particle counters and a thermo denuder were suspended by one rubber balloon. A particle counter measured the heated aerosol size distribution (after heating at the temperature of 300 degree by the thermo denuder) and the other measured the ambient aerosol size distribution during the observation. The observation was carried out on 15 January, 2015. Balloon arrived at the height of 30km and detailed information of aerosol size distributions in upper troposphere and lower stratosphere for both heated aerosol and ambient aerosol were obtained. As a Result, the number ratio of non-volatile particles to ambient aerosol particles in lower stratosphere (11-15km) showed different feature in particle size range of fine mode (0.3particles to ambient aerosol particles were 1-3% in fine mode range and 7-20% in coarse mode range. They suggested that fine particles are composed dominantly of volatile species (probably sulfuric acid), and coarse particles are composed of non-volatile species such as minerals, sea-salts. In our presentation, we show the obtained aerosol size distribution and discuss the aerosol compositions and their transport process.

  10. Observation of aerosol size distribution and new particle formation at a coastal city in the Yangtze River Delta, China.

    PubMed

    Shen, Lijuan; Wang, Honglei; Lü, Sheng; Li, Li; Yuan, Jing; Zhang, Xiaohan; Tian, Xudong; Tang, Qian

    2016-09-15

    Aerosol number size distribution in the range of 10nm-10μm, trace gases (O3, CO, SO2 and NO2), particular matter (PM: PM2.5 and PM10) and meteorological elements were measured from the 1st to the 31st of May, 2015, in the coastal city of Jiaxing in the Yangtze River Delta (YRD). The average number concentration and surface area concentration were 19,639cm(-3) and 427μm(2)cm(-3) during the observation period. The different mode particle concentrations ranked in the order of Aitken mode (12,361cm(-3))>nucleation (4926.7cm(-3))>accumulation (2349.3cm(-3))>coarse mode (1.7cm(-3)). The average concentrations of CO, SO2, NO2, O3, PM2.5 and PM10 were 0.545mgm(-3), 14.7, 35.1, 89.8, 43.5 and 64.6μgm(-3), respectively. Eight precipitation processes and 15 new particle formation (NPF) events (3 NPF events occurred on a rainy day) were observed. Results show that the precipitation process had greater scavenging effects on particles smaller than 120nm and larger than 2μm. The spectral distributions of number concentrations were unimodal at different weather conditions, with peaks at 20nm, 40-60nm, 50-80nm on NPF days, rainy days and normal days. During the NPF events, the formation rate (FR), growth rate (GR), condensational sink (CS), vapor source rate (Q) and condensing vapor concentration (C) were in the range of 4.0-17.0cm(-3)s(-1), 2.2-15.7nmh(-1), 1.5-5.8×10(-2)s(-1), 0.5-7.7×10(6)cm(-3)s(-1) and 3.0-21.5×10(7)cm(-3), with mean values of 9.6cm(-3)s(-1), 6.8nmh(-1), 3.4×10(-2)s(-1), 3.3×10(6)cm(-3)s(-1) and 9.4×10(7)cm(-3), respectively. NPF events normally occurred under clean atmospheric conditions with low PM concentrations but high levels of trace gases. It was also found that SO2 plays an important role in NPF and growth in Jiaxing. PMID:27261424

  11. Global Aerosol Observations

    Atmospheric Science Data Center

    2013-04-19

    ... atmosphere, directly influencing global climate and human health. Ground-based networks that accurately measure column aerosol amount and ... being used to improve Air Quality Models and for regional health studies. To assess the human-health impact of chronic aerosol exposure, ...

  12. Electronic cigarette aerosol particle size distribution measurements.

    PubMed

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

    2012-12-01

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

  13. 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. PMID:27162963

  14. Photochemical Aging of Organic Aerosol Particles

    NASA Astrophysics Data System (ADS)

    Nizkorodov, S. A.; Bateman, A. P.; Dailo, M.; Do, T.; Mang, S. A.; Pan, X.; Underwood, J. S.; Walser, M. L.

    2007-05-01

    Secondary Organic Aerosol (SOA) particles are produced in the atmosphere as a result of oxidation of volatile organic compounds (VOC). Primary Organic Aerosol (POA) particles are directly emitted in the atmosphere by their sources. This research focuses on the mechanisms of direct photochemical processes taking place in model SOA and POA particles, the role of such processes in aging of organic aerosol particles, and the effect of photochemistry on particles' physicochemical properties. To address these questions, artificial SOA and POA particles are investigated with several laboratory-based approaches relying on cavity ring-down spectroscopy and mass-spectrometry. SOA particles generated by dark oxidation of d-Limonene, alpha-Pinene, and beta-Pinene by ozone are all found to absorb radiation in the tropospheric actinic window. The UV absorption photolyzes SOA constituents resulting in a release of small VOC molecules back in the gas-phase, and considerable change in SOA chemical composition. For terpenes featuring a terminal double bond, the main SOA photolysis products are invariably found to be formaldehyde and formic acid. Similar observations are obtained for products of ozonolysis of thin films of unsaturated fatty acids and self-assembled monolayers of unsaturated alkenes. For the case of fatty acids, a very detailed mechanism of ozonolysis and subsequent photolysis is proposed. The photolytic activity is primarily attributed to organic peroxides and aldehydes. These results convincingly demonstrate that photochemical processes occurring inside SOA and POA particles age the particles on time scales that are shorter than typical lifetimes of aerosol particles in the atmosphere.

  15. 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

  16. Chemical and Physical Properties of Bulk Aerosols Observed During TRACE-P: Evidence of Nitrate Uptake on Dust Particles

    NASA Astrophysics Data System (ADS)

    Jordan, C.; Anderson, B.; Hudgins, C.; Winstead, E.; Thornhill, L.; Talbot, R.; Russo, R.; Scheuer, E.; Seid, G.; Dibb, J.; Fuelberg, H.

    2002-12-01

    Back trajectories and bulk aerosol chemical properties have been used to group aerosol samples measured on the DC-8 during TRACE-P into five source regions. Each of these source region groups was further subdivided into three altitude bins (< 2 km, 2 - 7 km, and > 7 km). The mean chemical signatures, size distributions, and other physical properties (e.g., volatility, single scatter albedo) will be presented for these groups. By combining chemical and physical measurements, the observed aerosol population for each group may be partitioned between black carbon, sea salts, non-sea salt water soluble ions, and dust. Using this approach, we have found that the bulk of the dust emanating from Asia during TRACE-P came from one region. The highest concentrations of pollution species were also found in this region, including particulate nitrate. The presence of gas phase pollutants such as nitric acid co-located with the dust allows for the uptake of gas-phase nitrogen onto the dust surfaces. Results show that in the dust sector at mid-altitudes (2 - 7 km), where the influence of sea salt is reduced compared to lower altitudes, 50% of the total nitrate is in particulate form. This is in contrast to 15% for sectors with little dust.

  17. 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.

  18. 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.

  19. Optical-chemical-microphysical relationships and closure studies for mixed carbonaceous aerosols observed at Jeju Island; 3-laser photoacoustic spectrometer, particle sizing, and filter analysis

    NASA Astrophysics Data System (ADS)

    Flowers, B. A.; Dubey, M. K.; Mazzoleni, C.; Stone, E. A.; Schauer, J. J.; Kim, S.-W.; Yoon, S. C.

    2010-11-01

    Transport of aerosols in pollution plumes from the mainland Asian continent was observed in situ at Jeju, South Korea during the Cheju Asian Brown Cloud Plume-Asian Monsoon Experiment (CAPMEX) field campaign throughout August and September 2008 using a 3-laser photoacoustic spectrometer (PASS-3), chemical filter analysis, and size distributions. The PASS-3 directly measures the effects of morphology (e.g. coatings) on light absorption that traditional filter-based instruments are unable to address. Transport of mixed sulfate, carbonaceous, and nitrate aerosols from various Asian pollution plumes to Jeju accounted for 74% of the deployment days, showing large variations in their measured chemical and optical properties. Analysis of eight distinct episodes, spanning wide ranges of chemical composition, optical properties, and source regions, reveals that episodes with higher organic carbon (OC)/sulfate (SO42-) and nitrate (NO3-)/SO42- composition ratios exhibit lower single scatter albedo at shorter wavelengths (ω405). We infer complex refractive indices (n-ik) as a function of wavelength for the high, intermediate, and low OC/SO42- pollution episodes by using the observed particle size distributions and the measured optical properties. The smallest mean particle diameter corresponds to the high OC/SO42- aerosol episode. The imaginary part of the refractive index (k) is greater for the high OC/SO42- episode at all wavelengths. A distinct, sharp increase in k at short wavelength implies enhanced light absorption by OC, which accounts for 50% of the light absorption at 405 nm, in the high OC/SO42- episode. Idealized analysis indicates increased absorption at 781 nm by factors greater than 3 relative to denuded black carbon in the laboratory. We hypothesize that coatings of black carbon cores are the mechanism of this enhancement. This implies that climate warming and atmospheric heating rates from black carbon particles can be significantly larger than have been

  20. Fatty Acids as Surfactants on Aerosol Particles

    NASA Astrophysics Data System (ADS)

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

    2003-12-01

    Russian forest and peat fires. Fatty acids were commonly observed on the surface layer of these particles. The chain length composition was characteristic to each emission source. In our previous work (Tervahattu et al., 2002), fatty acids on sea-salt particles were originated from dead sea plankton organisms with major peaks ranging from C14 to C18 and maximum at C16 (palmitic acid). Major peaks on the surface of forest fire particles ranged from C16 to C30 with the maximum at C24. This composition indicates the involvement of the smoke from both conifer trees and peat (Oros and Simoneit, 2000; 2001b). On the other hand, TOF-SIMS analysis of the surface of field fire particles showed major peaks from C14 to C30 with two maximums at C16 (highest intensity) and C22. It was concluded that the results indicate emissions from both grass burning and fossil fuels (Simoneit, 2002; Oros and Simoneit, 2000). The presence of surface film on aerosol particles may have an impact on their chemical, physical and optical properties and change their role in light scattering and as cloud condensation nuclei as well as interactions with human tissue.

  1. 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.

  2. Shipborne observations of atmospheric black carbon aerosol particles over the Arctic Ocean, Bering Sea, and North Pacific Ocean during September 2014

    NASA Astrophysics Data System (ADS)

    Taketani, Fumikazu; Miyakawa, Takuma; Takashima, Hisahiro; Komazaki, Yuichi; Pan, Xiaole; Kanaya, Yugo; Inoue, Jun

    2016-02-01

    Measurements of refractory black carbon (rBC) aerosol particles using a highly sensitive online single particle soot photometer were performed on board the R/V Mirai during a cruise across the Arctic Ocean, Bering Sea, and North Pacific Ocean (31 August to 9 October 2014). The measured rBC mass concentrations over the Arctic Ocean in the latitudinal region > 70°N were in the range 0-66 ng/m3 for 1 min averages, with an overall mean value of 1.0 ± 1.2 ng/m3. Single-particle-based observations enabled the measurement of such low rBC mass concentrations. The effects of long-range transport from continents to the Arctic Ocean were limited during the observed period, which suggests that the low rBC concentration levels would prevail over the Arctic Ocean. An analysis of rBC mixing states showed that particles with a nonshell/noncore structure made a significant contribution to the rBC particles detected over the Arctic Ocean.

  3. Probing the bulk viscosity of particles using aerosol optical tweezers

    NASA Astrophysics Data System (ADS)

    Power, Rory; Bones, David L.; Reid, Jonathan P.

    2012-10-01

    Holographic aerosol optical tweezers can be used to trap arrays of aerosol particles allowing detailed studies of particle properties and processes at the single particle level. Recent observations have suggested that secondary organic aerosol may exist as ultra-viscous liquids or glassy states at low relative humidity, potentially a significant factor in influencing their role in the atmosphere and their activation to form cloud droplets. A decrease in relative humidity surrounding a particle leads to an increased concentration of solute in the droplet as the droplet returns to equilibrium and, thus, an increase in the bulk viscosity. We demonstrate that the timescales for condensation and evaporation processes correlate with particle viscosity, showing significant inhibition in mass transfer kinetics using ternary sucrose/sodium chloride/water droplets as a proxy to atmospheric multi-component aerosol. We go on to study the fundamental process of aerosol coagulation in aerosol particle arrays, observing the relaxation of non-spherical composite particles formed on coalescence. We demonstrate the use of bright-field imaging and elastic light scattering to make measurements of the timescale for the process of binary coalescence contrasting the rheological properties of aqueous sucrose and sodium chloride aerosol over a range of relative humidities.

  4. 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.

  5. Observation of Organic Molecules at the Aerosol Surface.

    PubMed

    Wu, Yajing; Li, Wanyi; Xu, Bolei; Li, Xia; Wang, Han; McNeill, V Faye; Rao, Yi; Dai, Hai-Lung

    2016-06-16

    Organic molecules at the gas-particle interface of atmospheric aerosols influence the heterogeneous chemistry of the aerosol and impact climate properties. The ability to probe the molecules at the aerosol particle surface in situ therefore is important but has been proven challenging. We report the first successful observations of molecules at the surface of laboratory-generated aerosols suspended in air using the surface-sensitive technique second harmonic light scattering (SHS). As a demonstration, we detect trans-4-[4-(dibutylamino)styryl]-1-methylpyridinium iodide and determine its population and adsorption free energy at the surface of submicron aerosol particles. This work illustrates a new and versatile experimental approach for studying how aerosol composition may affect the atmospheric properties. PMID:27249662

  6. Mars aerosol studies with the MGS TES emission phase function observations: Optical depths, particle sizes, and ice cloud types versus latitude and solar longitude

    NASA Astrophysics Data System (ADS)

    Clancy, R. Todd; Wolff, Michael J.; Christensen, Philip R.

    2003-09-01

    Emission phase function (EPF) observations taken in 1999-2001 by Mars Global Surveyor Thermal Emission Spectrometer (MGS TES) support the broadest study of Martian aerosol properties to date. TES solar band and infrared (IR) spectral EPF sequences are analyzed to obtain first-time seasonal/latitudinal distributions of visible optical depths, particle sizes, and single scattering phase functions. This combined angular and wavelength coverage enables identification of two distinct ice cloud types over 45°S-45°N. Type 1 ice clouds exhibit small particle sizes (reff = 1-2 μm) and a distinctive backscattering increase. They are most prevalent in the southern hemisphere during aphelion, but also appear more widely distributed in season and latitude as topographic and high-altitude (>=20 km) ice hazes. Type 2 ice clouds exhibit larger particle sizes (reff = 3-4 μm), a distinct side-scattering minimum at 90-100° phase angles (characteristic of a change in particle shape relative to the type 1), and appear most prominently in the northern subtropical aphelion cloud belt. The majority of retrieved dust visible-to-IR optical depth ratios are indicative of reff = 1.5 +/- 0.1 μm, consistent with Pathfinder and Viking/Mariner 9 reanalyses. However, increased ratios (2.7 versus 1.7) appear frequently in the northern hemisphere over LS = 50-200°, indicating substantially smaller dust particles sizes (reff = 1.0 +/- 0.2 μm) at this time. In addition, larger (reff = 1.8-2.5 μm) dust particles were observed locally in the southern hemisphere during the peak of the 2001 global dust storm. Detailed spectral modeling of the TES visible band pass indicates agreement of EPF-derived dust single scattering albedos (0.92-0.94) with the spectrally resolved results from Pathfinder observations.

  7. A numerical determination of the evolution of cloud drop spectra due to condensation on natural aerosol particles

    NASA Technical Reports Server (NTRS)

    Lee, I. Y.; Haenel, G.; Pruppacher, H. R.

    1980-01-01

    The time variation in size of aerosol particles growing by condensation is studied numerically by means of an air parcel model which allows entrainment of air and aerosol particles. Particles of four types of aerosols typically occurring in atmospheric air masses were considered. The present model circumvents any assumption about the size distribution and chemical composition of the aerosol particles by basing the aerosol particle growth on actually observed size distributions and on observed amounts of water taken up under equilibrium by a deposit of the aerosol particles. Characteristic differences in the drop size distribution, liquid water content and supersaturation were found for the clouds which evolved from the four aerosol types considered.

  8. CALIPSO Observations of Aerosol Properties Near Clouds

    NASA Technical Reports Server (NTRS)

    Marshak, Alexander; Varnai, Tamas; Yang, Weidong

    2010-01-01

    Clouds are surrounded by a transition zone of rapidly changing aerosol properties. Characterizing this zone is important for better understanding aerosol-cloud interactions and aerosol radiative effects as well as for improving satellite measurements of aerosol properties. We present a statistical analysis of a global dataset of CALIPSO (Cloud-Aerosol Lidar and infrared Pathfinder Satellite Observation) Lidar observations over oceans. The results show that the transition zone extends as far as 15 km away from clouds and it is ubiquitous over all oceans. The use of only high confidence level cloud-aerosol discrimination (CAD) data confirms the findings. However, the results underline the need for caution to avoid biases in studies of satellite aerosol products, aerosol-cloud interactions, and aerosol direct radiative effects.

  9. Global CALIPSO Observations of Aerosol Changes Near Clouds

    NASA Technical Reports Server (NTRS)

    Varnai, Tamas; Marshak, Alexander

    2011-01-01

    Several recent studies have found that clouds are surrounded by a transition zone of rapidly changing aerosol optical properties and particle size. Characterizing this transition zone is important for better understanding aerosol-cloud interactions and aerosol radiative effects, and also for improving satellite retrievals of aerosol properties. This letter presents a statistical analysis of a monthlong global data set of Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) lidar observations over oceans. The results show that the transition zone is ubiquitous over all oceans and extends up to 15 km away from clouds. They also show that near-cloud enhancements in backscatter and particle size are strongest at low altitudes, slightly below the top of the nearest clouds. Also, the enhancements are similar near illuminated and shadowy cloud sides, which confirms that the asymmetry of Moderate Resolution Imaging Spectroradiometer reflectances found in an earlier study comes from 3-D radiative processes and not from differences in aerosol properties. Finally, the effects of CALIPSO aerosol detection and cloud identification uncertainties are discussed. The findings underline the importance of accounting for the transition zone to avoid potential biases in studies of satellite aerosol products, aerosol-cloud interactions, and aerosol direct radiative effects.

  10. Multi-satellite aerosol observations in the vicinity of clouds

    NASA Astrophysics Data System (ADS)

    Várnai, T.; Marshak, A.; Yang, W.

    2013-04-01

    Improved characterization of aerosol properties in the vicinity of clouds is important for better understanding two critical aspects of climate: aerosol-cloud interactions and the direct radiative effect of aerosols. Satellite measurements have provided important insights into aerosol properties near clouds, but also suggested that the observations can be affected by 3-D radiative processes and instrument blurring not considered in current data interpretation methods. This study examines systematic cloud-related changes in particle properties and radiation fields that influence satellite measurements of aerosols in the vicinity of low-level maritime clouds. For this, the paper presents a statistical analysis of a yearlong global dataset of co-located MODIS and CALIOP observations and theoretical simulations. The results reveal that CALIOP-observed aerosol particle size and optical thickness, and MODIS-observed solar reflectance increase systematically in a wide transition zone around clouds. It is estimated that near-cloud changes in particle populations - including both aerosols and undetected cloud particles - are responsible for roughly two thirds of the observed increase in 0.55 μm MODIS reflectance. The results also indicate that 3-D radiative processes significantly contribute to near-cloud reflectance enhancements, while instrument blurring contributes significantly only within 1 km from clouds and then quickly diminishes with distance from clouds.

  11. Hygroscopic behavior of NaCl-MgCl2 mixture particles as nascent sea-spray aerosol surrogates and observation of efflorescence during humidifying process

    NASA Astrophysics Data System (ADS)

    Gupta, D.; Eom, H.-J.; Cho, H.-R.; Ro, C.-U.

    2015-07-01

    NaCl and MgCl2 are the two major constituents of seawater, so NaCl-MgCl2 mixture particles can be a better representative of sea-spray aerosols (SSAs) than pure NaCl. However, there have been very few hygroscopic studies of pure MgCl2 and NaCl-MgCl2 mixture aerosol particles despite the MgCl2 moiety playing a major role in the hygroscopic behavior of nascent SSAs. Laboratory-generated pure MgCl2 and NaCl-MgCl2 mixture aerosol particles with 12 mixing ratios (0.01 ≤ mole fraction of NaCl (XNaCl) ≤ 0.9) were examined systematically by optical microscopy, in-situ Raman microspectrometry (RMS), and scanning electron microscopy/energy dispersive X-ray spectrometry (SEM/EDX) elemental X-ray mapping to observe their hygroscopic behavior, derive the experimental phase diagrams, and obtain the chemical micro-structures. Dry-deposited MgCl2·6H2O particles exhibited a deliquescence relative humidity (DRH) of ∼ 33.0 % and an efflorescence RH (ERH) of 10.8-9.1 %, whereas the nebulized pure MgCl2 and MgCl2-dominant particles of XNaCl = 0.026 (eutonic) and 0.01 showed single-stage transitions at DRH of ∼ 15.9 % and ERH of 10.1-3.2 %. The characteristic OH-stretching Raman signatures indicated the crystallization of MgCl2·4H2O at low RHs, suggesting that the kinetic barrier to MgCl2·6H2O crystallization is not overcome in the timescale of the dehydration measurements. The NaCl-MgCl2 mixture particles of 0.05 ≤ XNaCl ≤ 0.9 generally showed two-stage deliquescence: first at the mutual DRH (MDRH) of ~ 15.9 %; and second with the complete dissolution of NaCl at the second DRHs depending on the mixing ratios, resulting in a phase diagram composed of three distinct phases. During dehydration, most particles of 0.05 ≤ XNaCl ≤ 0.9 exhibited two-stage efflorescence: first, by the homogeneous nucleation of NaCl; and second, at mutual ERH (MERH) of ∼ 10.4-2.9 %, by the crystallization of the MgCl2·4H2O moiety, also resulting in three distinct phases. Interestingly

  12. Hygroscopic behavior of NaCl-MgCl2 mixture particles as nascent sea-spray aerosol surrogates and observation of efflorescence during humidification

    NASA Astrophysics Data System (ADS)

    Gupta, D.; Eom, H.-J.; Cho, H.-R.; Ro, C.-U.

    2015-10-01

    As Na+, Mg2+, and Cl- are major ionic constituents of seawater, NaCl-MgCl2 mixture particles might represent sea-spray aerosols (SSAs) better than pure NaCl. However, there have been very few hygroscopic studies of pure MgCl2 and NaCl-MgCl2 mixture aerosol particles despite the MgCl2 moiety playing a major role in the hygroscopic behavior of nascent SSAs. Laboratory-generated pure MgCl2 and NaCl-MgCl2 mixture aerosol particles with 12 mixing ratios (0.01 ≤ mole fraction of NaCl (XNaCl) ≤ 0.9) were examined systematically by optical microscopy (OM), in situ Raman micro-spectrometry (RMS), and scanning electron microscopy/energy dispersive X-ray spectrometry (SEM/EDX) elemental X-ray mapping to observe their hygroscopic behavior, derive the experimental phase diagrams, and obtain the chemical micro-structures. Dry-deposited MgCl2 ⋅ 6H2O particles exhibited a deliquescence relative humidity (DRH) of ~ 33.0 % and an efflorescence RH (ERH) of 10.8-9.1 %, whereas the nebulized pure MgCl2 and MgCl2-dominant particles of XNaCl = 0.026 (eutonic) and 0.01 showed single-stage transitions at DRH of ~ 15.9 % and ERH of 10.1-3.2 %. The characteristic OH-stretching Raman signatures indicated the crystallization of MgCl2 ⋅ 4H2O at low relative humidities (RHs), suggesting that the kinetic barrier to MgCl2 ⋅ 6H2O crystallization is not overcome in the timescale of the dehydration measurements. The NaCl-MgCl2 mixture particles of 0.05 ≤ XNaCl ≤ 0.9 generally showed two-stage deliquescence: first at the mutual DRH (MDRH) of ~ 15.9 %; and second with the complete dissolution of NaCl at the second DRHs depending on the mixing ratios, resulting in a phase diagram composed of three distinct phases. During dehydration, most particles of 0.05 ≤ XNaCl ≤ 0.9 exhibited two-stage efflorescence: first, by the homogeneous nucleation of NaCl; and second, at mutual ERH (MERH) of ~ 10.4-2.9 %, by the crystallization of the MgCl2 ⋅ 4H2O moiety, also resulting in three

  13. Biogenic Contributions to Summertime Arctic Aerosol: Observations of Aerosol Composition from the Netcare 2014 Aircraft Campaign

    NASA Astrophysics Data System (ADS)

    Willis, M. D.; Burkart, J.; Koellner, F.; Schneider, J.; Bozem, H.; Hoor, P. M.; Brauner, R.; Herber, A. B.; Leaitch, W. R.; Abbatt, J.

    2014-12-01

    The Arctic is a complex and poorly studied aerosol environment, impacted by strong anthropogenic contributions during winter months and by regional sources in cleaner summer months. In order to gain a predictive understanding of the changing climate in this region, it is necessary to understand the balance between these two aerosol sources to clarify how aerosol might be altered by or contribute to climate change. We present results of vertically resolved, submicron aerosol composition from an Aerodyne high-resolution aerosol mass spectrometer (AMS) during the NETCARE 2014 Polar6 aircraft campaign. The campaign was based in the high Arctic, at Resolute, NU (74°N), allowing measurements from 60 to 2900 meters over ice, open water and near the ice-edge. Concurrent measurements aboard the Polar6 included ultrafine and accumulation mode particle number and size, cloud condensation nuclei concentrations, trace gas concentrations and single particle composition. Aerosol vertical profiles measured by the AMS can be broadly characterized into two regimes corresponding to different meteorological conditions: the first with very low aerosol loading (<0.1 μg/m3) at low altitudes compared to that aloft and high numbers of nucleation mode particles, and the second with higher concentrations at lower levels. This second regime was associated with low concentrations of nucleation mode particles, and higher observable levels of methane sulphonic acid (MSA) from AMS measurements at low altitudes. MSA, produced during the oxidation of dimethyl sulphide, is a marker for the contribution of ocean-derived biogenic sulphur to particulate sulphur and could be identified and quantified using the high-resolution AMS. MSA to sulphate ratios were observed to increase towards lower altitudes, suggesting a contribution to aerosol loading from the ocean. In addition, we present measurements of aerosol neutralization and the characteristics of organic aerosol that relate to the growth of

  14. Comparison of MADE3-simulated and observed aerosol distributions with a focus on aerosol vertical profiles

    NASA Astrophysics Data System (ADS)

    Kaiser, Christopher; Hendricks, Johannes; Righi, Mattia; Jöckel, Patrick

    2016-04-01

    The reliability of aerosol radiative forcing estimates from climate models depends on the accuracy of simulated global aerosol distribution and composition, as well as on the models' representation of the aerosol-cloud and aerosol-radiation interactions. To help improve on previous modeling studies, we recently developed the new aerosol microphysics submodel MADE3 that explicitly tracks particle mixing state in the Aitken, accumulation, and coarse mode size ranges. We implemented MADE3 into the global atmospheric chemistry general circulation model EMAC and evaluated it by comparison of simulated aerosol properties to observations. Compared properties include continental near-surface aerosol component concentrations and size distributions, continental and marine aerosol vertical profiles, and nearly global aerosol optical depth. Recent studies have shown the specific importance of aerosol vertical profiles for determination of the aerosol radiative forcing. Therefore, our focus here is on the evaluation of simulated vertical profiles. The observational data is taken from campaigns between 1990 and 2011 over the Pacific Ocean, over North and South America, and over Europe. The datasets include black carbon and total aerosol mass mixing ratios, as well as aerosol particle number concentrations. Compared to other models, EMAC with MADE3 yields good agreement with the observations - despite a general high bias of the simulated mass mixing ratio profiles. However, BC concentrations are generally overestimated by many models in the upper troposphere. With MADE3 in EMAC, we find better agreement of the simulated BC profiles with HIPPO data than the multi-model average of the models that took part in the AeroCom project. There is an interesting difference between the profiles from individual campaigns and more "climatological" datasets. For instance, compared to spatially and temporally localized campaigns, the model simulates a more continuous decline in both total

  15. Standard aerosols for particle velocimeters

    NASA Technical Reports Server (NTRS)

    Deepark, A.; Ozarski, R.; Thomson, J. A. L.

    1976-01-01

    System consists of laser-scattering counter (LSC) and photographic system. Photographic system provides absolute method of measuring aerosol size-distribution independently of their light scattering properties. LSC comprises 1-mW He/Ne laser, input optics, collecting optics, photodetector, and signal-processing electronics.

  16. 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.

  17. 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.

  18. 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.

  19. Fog and Cloud Induced Aerosol Modification Observed by AERONET

    NASA Technical Reports Server (NTRS)

    Eck, T. F.; Holben, B. N.; Reid, J. S.; Giles, D. M.; Rivas, M. A.; Singh, R. P.; Tripathi, S. N.; Bruegge, C. J.; Platnick, S. E.; Arnold, G. T.; Krotkov, N. A.; Carn, S. A.; Sinyuk, A.; Dubovik, O.; Arola, A.; Schafer, J. S.; Artaxo, P.; Smirnov, A.; Chen, H.; Goloub, P.

    2011-01-01

    Large fine mode (sub-micron radius) dominated aerosols in size distributions retrieved from AERONET have been observed after fog or low-altitude cloud dissipation events. These column-integrated size distributions have been obtained at several sites in many regions of the world, typically after evaporation of low altitude cloud such as stratocumulus or fog. Retrievals with cloud processed aerosol are sometimes bimodal in the accumulation mode with the larger size mode often approx.0.4 - 0.5 microns radius (volume distribution); the smaller mode typically approx.0.12 to aprrox.0.20 microns may be interstitial aerosol that were not modified by incorporation in droplets and/or aerosol that are less hygroscopic in nature. Bimodal accumulation mode size distributions have often been observed from in situ measurements of aerosols that have interacted with clouds, and AERONET size distribution retrievals made after dissipation of cloud or fog are in good agreement with particle sizes measured by in situ techniques for cloud-processed aerosols. Aerosols of this type and large size range (in lower concentrations) may also be formed by cloud processing in partly cloudy conditions and may contribute to the shoulder of larger size particles in the accumulation mode retrievals, especially in regions where sulfate and other soluble aerosol are a significant component of the total aerosol composition. Observed trends of increasing aerosol optical depth (AOD) as fine mode radius increased suggests higher AOD in the near cloud environment and therefore greater aerosol direct radiative forcing than typically obtained from remote sensing, due to bias towards sampling at low cloud fraction.

  20. Heterogeneous Reactions in Atmospheric Aerosols Observed Using ATOFMS

    NASA Astrophysics Data System (ADS)

    Ryan, Sullivan

    2005-03-01

    The heterogeneous aging of natural atmospheric particles by reactive gases in the troposphere has been investigated in a flow-tube reactor using Aerosol Time-of-Flight Mass Spectrometry (ATOFMS) to monitor changes in the particle composition in real-time. Sea- salt and mineral dust aerosols were introduced into the flow tube simultaneously and reacted with nitric acid in a relative rate experiment. ATOFMS is a single-particle technique and thus enables us to distinguish which particle type accumulates more nitric acid. This allows us to determine if the differing surface area or kinetics is driving the partitioning of nitric acid between the sea salt and dust. The results of these and other aerosol flow-tube kinetics experiments will be presented. The atmospheric implications will be emphasized, particularly in relation to observations made by ATOFMS of heterogeneous reactions occurring in particles over the Pacific Ocean during ACE-Asia.

  1. Retrieval of Aerosol Absorption Properties from Satellite Observations

    NASA Technical Reports Server (NTRS)

    Torres, Omar; Bhartia, Pawan K.; Jethva, H.; Ahn, Chang-Woo

    2012-01-01

    The Angstrom Absorption Exponent (AAE) is a parameter commonly used to characterize the wavelength-dependence of aerosol absorption optical depth (AAOD). It is closely related to aerosol composition. Black carbon (BC) containing aerosols yield AAE values near unity whereas Organic carbon (OC) aerosol particles are associated with values larger than 2. Even larger AAE values have been reported for desert dust aerosol particles. Knowledge of spectral AAOD is necessary for the calculation of direct radiative forcing effect of aerosols and for inferring aerosol composition. We have developed a satellitebased method of determining the spectral AAOD of absorbing aerosols. The technique uses multi-spectral measurements of upwelling radiation from scenes where absorbing aerosols lie above clouds as indicated by the UV Aerosol Index. For those conditions, the satellite measurement can be explained, using an approximations of Beer's Law (BL), as the upwelling reflectance at the cloud top attenuated by the absorption effects of the overlying aerosol layer. The upwelling reflectance at the cloud-top in an aerosol-free atmospheric column is mainly a function of cloud optical depth (COD). In the proposed method of AAE derivation, the first step is determining COD which is retrieved using a previously developed color-ratio based approach. In the second step, corrections for molecular scattering effects are applied to both the observed ad the calculated cloud reflectance terms, and the spectral AAOD is then derived by an inversion of the BL approximation. The proposed technique will be discussed in detail and application results making use of OMI multi-spectral measurements in the UV-Vis. will be presented.

  2. 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

  3. Holographic interferometry for aerosol particle characterization

    NASA Astrophysics Data System (ADS)

    Berg, Matthew J.; Subedi, Nava R.

    2015-01-01

    Using simulations based on Mie theory, this work shows how double-exposure digital holography can be used to measure the change in size of an expanding, or contracting, spherical particle. Here, a single particle is illuminated by a plane wave twice during its expansion: once when the particle is 27 λ in radius, and again when it is 47 λ. A hologram is formed from each illumination stage from the interference of the scattered and unscattered, i.e., incident, light. The two holograms are then superposed to form a double exposure. By applying the Fresnel-Kirchhoff diffraction theory to the double-exposed hologram, a silhouette-like image of the particle is computationally reconstructed that is superposed with interference fringes. These fringes are a direct result of the change in particle size occurring between the two illumination stages. The study finds that expansion on the scale of ~ 6 λ is readily discerned from the reconstructed particle image. This work could be important for improved characterization of single and multiple aerosol particles in situ. For example, by illuminating an aerosol particle with infrared light, it may be possible to measure photothermally induced particle expansion, thus providing insight into a particle's material properties simultaneous with an image of the particle.

  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. SCAVENGING OF AEROSOL PARTICLES BY PRECIPITATION

    EPA Science Inventory

    Airborne measurements have been made of aerosol particle size distributions (>0.01 micrometer) in aged air masses, in the plumes from several coal power plants and a large Kraft paper mill, and in the emissions from a volcano, before and after rain or snow showers. These measurem...

  6. Global Lidar Observations of Aerosol Distribution and Radiative Influence

    NASA Technical Reports Server (NTRS)

    Spinhirne, James; Starr, David OC. (Technical Monitor)

    2001-01-01

    A very visible impact of human activities is the brownish aerosol haze that pervades many industrialized regions as well as areas in the subtropics and tropics where biomass burning occurs. Well known examples are the Asian Brown Cloud, Arctic Haze and East Coast Haze. Atmospheric transport transforms this haze into regional and hemispheric aerosol layers of significant concentrations. The overall impact on the radiation balance of the atmosphere, surface solar irradiance and other meteorology factors is recognized as a major uncertainty for climate change. In order to understand the impact, the global distribution of aerosol and their properties must be known. . A missing element of observations, but critical for understanding transport has been the height distribution of aerosol. Lidar measurements of aerosol height distribution have been important in GLOBE, ACE, INDOEX and other field studies A network of continuously operating eye safe lidar ground sites has now been established for baseline aerosol profiling. In 2002 NASA will launch the Geoscience Laser Altimeter System (GLAS) mission which will provide for the first time global observations of the height distribution of aerosol. The combination of these and other modem satellite observations, field experiments and models of global aerosol composition and transport should begin to unravel the impacts of particles in the atmosphere.

  7. 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.

  8. 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.

  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. Aerosol and bioaerosol particles in a dental office.

    PubMed

    Polednik, Bernard

    2014-10-01

    This study reports comprehensive aerosol and bioaerosol measurements in a dental office. The highest submicrometer particle concentrations were observed during dental grinding and they were on average 16 times higher than the indoor background. Certain metallic trace elements and total carbon concentrations were significantly elevated (>10 times) in the particles deposited in the operating room. Dental procedures also contributed to increased bacterial contamination that may pose a health risk both for dental personnel and patients. PMID:25218707

  11. 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

  12. Analysis and interpretation of lidar observations of the stratospheric aerosol

    NASA Technical Reports Server (NTRS)

    Hamill, P.; Swissler, T. J.; Osborn, M.; Mccormick, M. P.

    1980-01-01

    Data obtained with a 48 in. telescope lidar system are compared with results obtained using a one-dimensional stratospheric aerosol model to analyze various microphysical processes influencing the formation of this aerosol. Special attention is given to the following problems: (1) how lidar data can help determine the composition of the aerosol particles and (2) how the layer corresponds to temperature profile variations. The lidar record during the period 1974 to 1979 shows a considerable decrease of the peak value of the backscatter ratio. Seasonal variations in the aerosol layer and a gradual decrease in stratospheric loading are observed. The aerosol model simulates a background stratospheric aerosol layer, and it predicts stratospheric aerosol concentrations and compositions. Numerical experiments are carried out by using the model and by comparing the theoretical results with the experimentally obtained lidar record. Comparisons show that the backscatter profile is consistent with the composition when the particles are sulfuric acid and water; it is not consistent with an ammonium sulfate composition. It is shown that the backscatter ratio is not sensitive to the composition or stratospheric loading of condensation nuclei such as meteoritic debris.

  13. 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

  14. Aerosol observations and growth rates in the tropical tropopause layer

    NASA Astrophysics Data System (ADS)

    Waddicor, D. A.; Vaughan, G.; Choularton, T. W.; Bower, K. N.; Coe, H.; Gallagher, M.; Williams, P. I.; Flynn, M.; Volz-Thomas, A.; Pätz, W.; Isaac, P.; Hacker, J.; Arnold, F.; Schlager, H.; Whiteway, J. A.

    2012-01-01

    We present a case study of Aitken and accumulation mode aerosol observed downwind of the anvils of deep tropical thunderstorms. The measurements were made by condensation nuclei counters flown on the Egrett high-altitude aircraft from Darwin during the ACTIVE campaign, in monsoon conditions producing widespread convection over land and ocean. Maximum measured concentrations of aerosol in the size range 10-100 nm were 25 000 cm-3 STP. By calculating back-trajectories from the observations, and projecting on to infrared satellite images, the time since the air exited cloud was estimated. In this way a time scale of ~ 3-4 h was derived for the 10-100 nm aerosol concentration to reach its peak. We examine the hypothesis that the growth in aerosol concentrations can be explained by production of sulphuric acid from SO2 followed by particle nucleation and coagulation. Estimates of the sulphuric acid production rate show that the observations are only consistent with this hypothesis if the particles coagulate to sizes > 10 nm much more quickly than is suggested by current theory. Alternatively, other condensible gases (possibly organic) drive the growth of aerosol particles in the TTL.

  15. Particle size distribution of indoor aerosol sources

    SciTech Connect

    Shah, K.B.

    1990-10-24

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

  16. Condensation on Aerosol Particles and its Inhibition.

    NASA Astrophysics Data System (ADS)

    Liu, Peter Shen King

    The atmospheric aerosol is of primary importance in the formation of precipitation. Except in the neighbourhood of large sources of pollution most of the atmospheric particles are of natural origin, but human contribution is increasing at such a rate that within a comparatively short time it may equal nature's. Such an increase in the atmospheric particulate load may have significant effects on the distribution and intensity of precipitation. There is a general perception that most of the atmospheric particulate load is soluble in water or has some soluble component and soluble particles condense water more readily than insoluble. In this work a study is made of the solubility of the atmospheric aerosol at various relative humidities. The results confirm that much of the atmospheric aerosol is indeed soluble, but that the soluble proportion is highly variable. This result has significant implications for studies of air pollution in which the respirable fraction of the atmospheric aerosol is deduced from the results of long term dichotomous sampling. Results are also presented of studies in which an attempt was made to inhibit the condensation of water on man-made and adventitious particles with a view to modifying their possible climatic effects. This work has demonstrated that certain agents, notably long chain amines, do indeed have an inhibiting effect on the condensation of water on particles which have been exposed to them, but that the effect of the agents so far tested is not sufficiently great to be of immediate practical importance. It is concluded that further advances must await more precise methods of producing small supersaturations reliably and reproducibly.

  17. Retrieval of Stratospheric Aerosol Properties from SCIAMACHY limb observations

    NASA Astrophysics Data System (ADS)

    Doerner, S.; Kühl, S.; Pukite, J.; Penning de Vries, M. J.; Hoermann, C.; von Savigny, C.; Deutschmann, T.; Wagner, T.

    2012-12-01

    Since the start of the Stratospheric Aerosol Measurement program in 1975 satellites have been improving our understanding of the global distribution of trace gases, clouds and aerosols. Observations in occultation and limb geometry provide profile information on stratospheric aerosol, which have an important influence on the global radiation budget (e.g., after strong volcanic eruptions) and the stratospheric ozone chemistry (e.g., the chlorine activation inside the polar vortex). The Scanning Imaging Absorption Spectrometer for Atmospheric CHartographY (SCIAMACHY) on ENVISAT performed measurements in limb geometry for almost ten years between 2002 and 2012. Its vertical resolution of about 3.3 km at the tangent point and the broad spectral range (UV/VIS/NIR) allow to retrieve profile information of stratospheric trace gases (e.g., O3, NO2, BrO or OClO) and stratospheric aerosol properties. Pioneering studies (e.g., Savigny et al., 2005) showed that in particular from color indices (including the near IR spectral range) signatures of stratospheric aerosols and polar stratospheric clouds (PSCs) can be retrieved. In our study we investigate the sensitivity of SCIAMACHY's broad spectral range to aerosol particle properties by comparing measured spectra with simulated results from the 3D full spherical Monte Carlo Atmospheric Radiative Transfer Model McArtim. In particular, we focus on the absorption properties in the UV spectral range, the extinction coefficient and the Angström exponent. The final aim of our study is to use SCIAMACHY limb measurements for the profile retrieval of optical parameters (e.g., absorption and phase function) from which microphysical properties (e.g., mean aerosol particle diameter) of the stratospheric aerosol particles can be deduced.

  18. The stratospheric sulfate aerosol layer - Processes, models, observations, and simulations

    NASA Technical Reports Server (NTRS)

    Whitten, R. C.; Toon, O. B.; Turco, R. P.

    1980-01-01

    After briefly reviewing the observational data on the stratospheric sulfate aerosol layer, the chemical and physical processes that are likely to fix the properties of the layer are discussed. We present appropriate continuity equations for aerosol particles, and show how to solve the equations on a digital computer. Simulations of the unperturbed aerosol layer by various published models are discussed and the sensitivity of layer characteristics to variations in several aerosol model parameters is studied. We discuss model applications to anthropogenic pollution problems and demonstrate that moderate levels of aerospace activity (supersonic transport and Space Shuttle operations) will probably have only a negligible effect on global climate. Finally, we evaluate the possible climatic effect of a ten-fold increase in the atmospheric abundance of carbonyl sulfide.

  19. 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.

  20. Atmospheric Aerosol Nucleation: Formation of Sub-3 nm Particles and Their Subsequent Growth

    NASA Astrophysics Data System (ADS)

    Lee, S.

    2012-12-01

    Aerosol nucleation is an important step in the chain reaction that lead to cloud formation but the nucleation mechanisms are poorly understand. Most of the previous aerosol nucleation studies were based on measurements of particles, typically larger than 3 nm, so it was unclear how gas phase molecules nucleate to form clusters and how they further grow to become aerosol particles. In this presentation, we will show recent results of aerosol nucleation based on direct measurements of sub-3 nm particles. We will show laboratory studies of multicomponent nucleation involving sulfuric acid, ammonia, and organic amines and atmospheric observations made in various atmospheric conditions (biogenic, marine, and less polluted continental atmosphere).

  1. An evaluation of the impact of aerosol particles on weather forecasts from a biomass burning aerosol event over the Midwestern United States: observational-based analysis of surface temperature

    NASA Astrophysics Data System (ADS)

    Zhang, Jianglong; Reid, Jeffrey S.; Christensen, Matthew; Benedetti, Angela

    2016-05-01

    A major continental-scale biomass burning smoke event from 28-30 June 2015, spanning central Canada through the eastern seaboard of the United States, resulted in unforecasted drops in daytime high surface temperatures on the order of 2-5 °C in the upper Midwest. This event, with strong smoke gradients and largely cloud-free conditions, provides a natural laboratory to study how aerosol radiative effects may influence numerical weather prediction (NWP) forecast outcomes. Here, we describe the nature of this smoke event and evaluate the differences in observed near-surface air temperatures between Bismarck (clear) and Grand Forks (overcast smoke), to evaluate to what degree solar radiation forcing from a smoke plume introduces daytime surface cooling, and how this affects model bias in forecasts and analyses. For this event, mid-visible (550 nm) smoke aerosol optical thickness (AOT, τ) reached values above 5. A direct surface cooling efficiency of -1.5 °C per unit AOT (at 550 nm, τ550) was found. A further analysis of European Centre for Medium-Range Weather Forecasts (ECMWF), National Centers for Environmental Prediction (NCEP), United Kingdom Meteorological Office (UKMO) near-surface air temperature forecasts for up to 54 h as a function of Moderate Resolution Imaging Spectroradiometer (MODIS) Dark Target AOT data across more than 400 surface stations, also indicated the presence of the daytime aerosol direct cooling effect, but suggested a smaller aerosol direct surface cooling efficiency with magnitude on the order of -0.25 to -1.0 °C per unit τ550. In addition, using observations from the surface stations, uncertainties in near-surface air temperatures from ECMWF, NCEP, and UKMO model runs are estimated. This study further suggests that significant daily changes in τ550 above 1, at which the smoke-aerosol-induced direct surface cooling effect could be comparable in magnitude with model uncertainties, are rare events on a global scale. Thus, incorporating

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

    PubMed

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

    2009-03-01

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

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

    SciTech Connect

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

    2009-03-01

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

  4. SPICAV-SOIR mesospheric aerosols observations characterization and modelling

    NASA Astrophysics Data System (ADS)

    Wilquet, V.; Piccialli, A.; Vandaele, A. C.; Montmessin, F.; Bertaux, J. L.

    2013-09-01

    From independent retrievals for the 3 channels of the SPICAV/SOIR instrument, it has been postulated that the upper haze on Venus includes, in some instances, a bimodal population, one type of particles with a radius comprised between ~0.1 and 0.3 μm and the second type, detected in the IR, with a radius varying between ~0.4 and 1 μm. In addition, a high temporal variability in the aerosol loading was inferred from SOIR observations over 4 years, as well as a latitudinal dependency. We propose to refine the size distribution retrieval of aerosols based on the Mie theory and on the observed spectral dependence of light extinction in the spectra through a unique retrieval procedure combining the data from the 3 channels of the instrument. We also search for a dependence on altitude of the aerosol particles size distribution and of aerosol composition and compare the variations in aerosol loading to other key parameters retrieved such as water and SO2 composition or temperature.

  5. 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

    . Furthermore, we measured TC ^13C/12C isotopic ratio on each cascade. This ratio contributed to identifying sources of carbonaceous species. References Garbaras, A., Andriejauskiene, J., Bariseviciute, R., Remeikis, V., 2008. Tracing of atmospheric aerosol sources using stable carbon isotopes. Lithuanian J. Phys. 48, 259-264. Jaenicke, R., 1998. Atmospheric aerosol size distribution. In: Harrison, R.M., van Grieken, R.E. (Eds.), Atmospheric Particles. John Wiley & Sons, Chichester, pp. 1-28. Middlebrook, A.M., Murphy, D.M., Thomson, D.S., 1998. Observations of organic material in individual marine particles at Cape Grim during the first aerosol characterization experiment (ACE 1). Journal of Geophysical Research 103, 16475-16483. Norman, A.L., Hopper, J.F., Blanchard, P., Ernst, D., Brice, K., Alexandrou, N., Klouda, G., 1999. The stable carbon isotope composition of atmospheric PAHs. Atmospheric Environment 33 (17), 2807-2814. Samara, C., Voutsa, D., 2005. Size distribution of airborne particulate matter and associated heavy metals in the roadside environment. Chemosphere 59, 1197-1206.

  6. Oxodicarboxylic acids in atmospheric aerosol particles

    NASA Astrophysics Data System (ADS)

    Römpp, Andreas; Winterhalter, Richard; Moortgat, Geert K.

    Fine mode aerosol was collected on quartz fiber filters at several sites across Europe. These samples were analyzed for carboxylic acids by liquid chromatography coupled to a hybrid (quadrupole and time-of-flight) mass spectrometer (LC/MS/MS-TOF). A series of oxodicarboxylic acids (C 7-C 11) was detected. Oxodicarboxylic acids are linear dicarboxylic acids with an additional carbonyl group. Previous measurements of these acids are scarce and their sources are largely unknown. Several structural isomers (different positions of the carbonyl group within the molecule) could be identified and differentiated by the combination of laboratory experiments and high mass accuracy measurements. The homologs with 9-11 carbon atoms were identified for the first time in atmospheric aerosol particles. The concentrations of oxodicarboxylic acids in ambient aerosol samples frequently exceeded those of the corresponding unsubstituted dicarboxylic acids. Oxodicarboxylic acids have been shown to be products of the reaction of dicarboxylic acids with OH radicals in chamber experiments and a reaction mechanism is proposed. Good correlation of oxodicarboxylic acid and hydroxyl radical concentrations was found at two measurement sites (Finland and Crete) of different geographic location and meteorological conditions. The ratios of individual isomers from the field samples are comparable to those of the laboratory experiments. The results of this study imply that the reaction of OH radicals and dicarboxylic acids is an important pathway for the production of oxodicarboxylic acids in the atmosphere. Oxodicarboxylic acids seem to be important intermediates in atmospheric oxidation processes of organic compounds.

  7. Aerosol property retrieval from geostationary observations

    NASA Astrophysics Data System (ADS)

    Govaerts, Yves

    The Meteosat satellites play an important role for the generation of consistent long time series of aerosol properties. This importance relies on (i) the long duration of past (Meteosat First Generation, MFG) starting in 1982, present (Meteosat Second Generation, MSG) and future (Meteosat Third Generation, MTG) missions and (ii) their frequent cycle of acquisition that can be used to document the anisotropy of the surface and therefore the lower boundary condition for aerosol retrieval over land surfaces. Hence, a similar approach is used for the processing of each Meteosat generation based on a joint retrieval of surface reflectance and aerosol properties using an Optimal Estimation approach. Daily accumulation of the frequent Meteosat observations is used to discriminate the radiative effects that result from the surface anisotropy, from those caused by the aerosol scattering. The inverted forward model explicitly accounts for the surface anisotropy and the multiple scattering for the coupled surface-atmosphere system. Pinty et al. (2000) pioneered with the development of an original method to characterise simultaneously surface anisotropy and atmospheric scattering properties for the processing of MFG. Although these observations are limited to one single large VIS band poorly characterised, the main advantage of MFG relies in the duration of the archive (1982 - 2006), knowing that prior to 2000 space observations were very scarce. Despite these radiometric limitations, it is possible to detect major aerosol events like dust storms, fire plumes or pollution events, even over land surfaces. SEVIRI, on-board MSG, offers additional capabilities with its three solar channels and 15 min repeat cycle. AOD retrieval is much more accurate than with MFG and it is possible to discriminate among various aerosol classes. The additional FCI solar channels on-board MTG will offer improved capabilities with respect to MSG/SEVIRI for the retrieval of aerosol concentration and

  8. Sources and composition of urban aerosol particles

    NASA Astrophysics Data System (ADS)

    Vogt, M.; Johansson, C.; Mårtensson, M.; Struthers, H.; Ahlm, L.; Nilsson, D.

    2011-09-01

    From May 2008 to March 2009 aerosol emissions were measured using the eddy covariance method covering the size range 0.25 to 2.5 μm diameter (Dp) from a 105 m tower, in central Stockholm, Sweden. Supporting chemical aerosol data were collected at roof and street level. Results show that the inorganic fraction of sulfate, nitrate, ammonium and sea salt accounts for approximately 15% of the total aerosol mass <1 μm Dp (PM1) with water soluble soil contributing 11% and water insoluble soil 47%. Carbonaceous compounds were at the most 27% of PM1 mass. It was found that heating the air from the tower to 200 °C resulted in the loss of approximately 60% of the aerosol volume at 0.25 μm Dp whereas only 40% of the aerosol volume was removed at 0.6 μm Dp. Further heating to 300 °C caused very little additional losses <0.6 μm Dp. The chemical analysis did not include carbonaceous compounds, but based on the difference between the total mass concentration and the sum of the analyzed non-carbonaceous materials, it can be assumed that the non-volatile particulate material (heated to 300 °C) consists mainly of carbonaceous compounds, including elemental carbon. Furthermore, it was found that the non-volatile particle fraction <0.6 μm Dp correlated (r2 = 0.4) with the BC concentration at roof level in the city, supporting the assumption that the non-volatile material consists of carbonaceous compounds. The average diurnal cycles of the BC emissions from road traffic (as inferred from the ratio of the incremental concentrations of nitrogen oxides (NOx) and BC measured on a densely trafficked street) and the fluxes of non-volatile material at tower level are in close agreement, suggesting a traffic source of BC. We have estimated the emission factors (EFs) for non-volatile particles <0.6 μm Dp to be 2.4±1.4 mg veh-1 km-1 based on either CO2 fluxes or traffic activity data. Light (LDV) and heavy duty vehicle (HDV) EFs were estimated using multiple linear regression and

  9. Rural continental aerosol properties and processes observed during the Hohenpeissenberg Aerosol Characterization Experiment (HAZE2002)

    NASA Astrophysics Data System (ADS)

    Hock, N.; Schneider, J.; Borrmann, S.; Römpp, A.; Moortgat, G.; Franze, T.; Schauer, C.; Pöschl, U.; Plass-Dülmer, C.; Berresheim, H.

    2007-06-01

    particles. The average ratio of OM1 to OC2.5 was 2, indicating a high proportion of heteroelements in the organic fraction of the sampled rural aerosol. This is consistent with the high ratio of oxygenated organic aerosol (OOA) over hydrocarbon-like organic aerosol (HOA) inferred from the AMS results (4:1), and also with the high abundance of proteins (~3%) indicating a high proportion of primary biological material (~30%) in PM2.5. Moreover, the low abundance of PAHs (<1 ng m-3) and EC (<1 μg m-3) in PM2.5 confirm a low contribution of combustion emissions, which are usually also major sources for HOA. Slightly enhanced HOA concentrations indicating fresh anthropogenic emissions were observed during a period when air masses were advected from the densely populated Po Valley, Italy. Detection of several secondary organic aerosol compounds (dicarboxylic acids) and their precursors (monoterpenes) confirmed the finding that secondary aerosol from natural sources was an important aerosol constituent. A sharp decrease of the short lived monoterpenes indicated that during night-time the measurement station was isolated from ground emission sources by a stable inversion layer. Nighttime values can therefore be regarded to represent regional or long range transport. New particle formation was observed almost every day with particle number concentrations exceeding 104 cm-3 (nighttime background level 1000-2000 cm-3). Closer inspection of two major events indicated that ternary H2SO4/H2O/NH3 nucleation triggered particle formation and that condensation of both organic and inorganic species contributed to particle growth.

  10. The vertical distribution of Martian aerosol particle size

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  11. Formation of highly porous aerosol particles by atmospheric freeze-drying in ice clouds.

    PubMed

    Adler, Gabriela; Koop, Thomas; Haspel, Carynelisa; Taraniuk, Ilya; Moise, Tamar; Koren, Ilan; Heiblum, Reuven H; Rudich, Yinon

    2013-12-17

    The cycling of atmospheric aerosols through clouds can change their chemical and physical properties and thus modify how aerosols affect cloud microphysics and, subsequently, precipitation and climate. Current knowledge about aerosol processing by clouds is rather limited to chemical reactions within water droplets in warm low-altitude clouds. However, in cold high-altitude cirrus clouds and anvils of high convective clouds in the tropics and midlatitudes, humidified aerosols freeze to form ice, which upon exposure to subsaturation conditions with respect to ice can sublimate, leaving behind residual modified aerosols. This freeze-drying process can occur in various types of clouds. Here we simulate an atmospheric freeze-drying cycle of aerosols in laboratory experiments using proxies for atmospheric aerosols. We find that aerosols that contain organic material that undergo such a process can form highly porous aerosol particles with a larger diameter and a lower density than the initial homogeneous aerosol. We attribute this morphology change to phase separation upon freezing followed by a glass transition of the organic material that can preserve a porous structure after ice sublimation. A porous structure may explain the previously observed enhancement in ice nucleation efficiency of glassy organic particles. We find that highly porous aerosol particles scatter solar light less efficiently than nonporous aerosol particles. Using a combination of satellite and radiosonde data, we show that highly porous aerosol formation can readily occur in highly convective clouds, which are widespread in the tropics and midlatitudes. These observations may have implications for subsequent cloud formation cycles and aerosol albedo near cloud edges. PMID:24297908

  12. Formation of highly porous aerosol particles by atmospheric freeze-drying in ice clouds

    PubMed Central

    Adler, Gabriela; Koop, Thomas; Haspel, Carynelisa; Taraniuk, Ilya; Moise, Tamar; Koren, Ilan; Heiblum, Reuven H.; Rudich, Yinon

    2013-01-01

    The cycling of atmospheric aerosols through clouds can change their chemical and physical properties and thus modify how aerosols affect cloud microphysics and, subsequently, precipitation and climate. Current knowledge about aerosol processing by clouds is rather limited to chemical reactions within water droplets in warm low-altitude clouds. However, in cold high-altitude cirrus clouds and anvils of high convective clouds in the tropics and midlatitudes, humidified aerosols freeze to form ice, which upon exposure to subsaturation conditions with respect to ice can sublimate, leaving behind residual modified aerosols. This freeze-drying process can occur in various types of clouds. Here we simulate an atmospheric freeze-drying cycle of aerosols in laboratory experiments using proxies for atmospheric aerosols. We find that aerosols that contain organic material that undergo such a process can form highly porous aerosol particles with a larger diameter and a lower density than the initial homogeneous aerosol. We attribute this morphology change to phase separation upon freezing followed by a glass transition of the organic material that can preserve a porous structure after ice sublimation. A porous structure may explain the previously observed enhancement in ice nucleation efficiency of glassy organic particles. We find that highly porous aerosol particles scatter solar light less efficiently than nonporous aerosol particles. Using a combination of satellite and radiosonde data, we show that highly porous aerosol formation can readily occur in highly convective clouds, which are widespread in the tropics and midlatitudes. These observations may have implications for subsequent cloud formation cycles and aerosol albedo near cloud edges. PMID:24297908

  13. 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

  14. Composition and hygroscopicity of aerosol particles at Mt. Lu in South China: Implications for acid precipitation

    NASA Astrophysics Data System (ADS)

    Li, Weijun; Chi, Jianwei; Shi, Zongbo; Wang, Xinfeng; Chen, Bin; Wang, Yan; Li, Tao; Chen, Jianmin; Zhang, Daizhou; Wang, Zifa; Shi, Chune; Liu, Liangke; Wang, Wenxing

    2014-09-01

    Physicochemical properties of aerosol particles were studied at Mt. Lu, an elevated site (115°59‧E, 29°35‧N, 1165 m) within the acid precipitation area. Northeast winds transport copious amounts of air pollutants and water vapor from the Yangtze River Delta into this acid precipitation area. NH4+ and SO42- are the dominant ions in PM2.5 and determine aerosol acidity. Individual particle analysis shows abundant S-rich and metals (i.e. Fe-, Zn-, Mn-, and Pb-rich) particles. Unlike aerosol particles in North China and urban areas, there are little soot and mineral particles at Mt. Lu. Lack of mineral particles contributed to the higher acidity in precipitation in the research area. Nano-sized spherical metal particles were observed to be embedded in 37% of S-rich particles. These metal particles were likely originated from heavy industries and fired-power plants. Hygroscopic experiments show that most particles start to deliquesce at 73-76% but organic coating lowers the particle deliquescence relative humidity (DRH) to 63-73%. The DRHs of these aerosol particles are clearly smaller than that of pure ammonium sulfate particles which is 80%. Since RH in ambient air was relatively high, ranging from 65% to 85% during our study period, most particles at our sampling site were in liquid phase. Our results suggest that liquid phase reactions in aerosol particles may contribute to SO2 to sulfuric acid conversion in the acid precipitation area.

  15. In-situ observations of mesospheric aerosol particles and their impact on the D-region charge balance: Highlights from the ECOMA sounding rocket program (2006 - 2010)

    NASA Astrophysics Data System (ADS)

    Rapp, M.; Friedrich, M.; Strelnikov, B.; Hoppe, U.; Plane, J. M.

    2012-12-01

    Over the years 2006 - 2010 a total of 9 sounding rockets was successfully launched in the scope of the Norwegian-German ECOMA (= Existence and Charge state Of Meteoric smoke particles in the middle Atmosphere) project. While the primary target of these observations was the characterization of the properties of meteoric smoke particles (MSP), both MSP and mesospheric ice particles in the vicinity of the cold polar summer mesopause were investigated. This presentation gives an overview of the major results of this project covering subjects such as the charging properties of MSP and ice particles, the impact of this charging process on the D-region charge balance, and the microphysical properties of the MSP. Concerning the latter, emphasis is spent on the most recent results from a campaign in December 2010 during which two sounding rockets were launched with improved particle detectors that were designed to provide constraints on the photoelectric work function of the particles. These experimental results are further discussed on the basis of quantum mechanical calculations of the electronic structure of cluster molecules which are likely candidates for MSP. These calculations allow a tentative interpretation of the observations in terms of MSP size and altitude variations as well as their photoelectric properties.

  16. Rural continental aerosol properties and processes observed during the Hohenpeissenberg Aerosol Characterization Experiment (HAZE2002)

    NASA Astrophysics Data System (ADS)

    Hock, N.; Schneider, J.; Borrmann, S.; Römpp, A.; Moortgat, G.; Franze, T.; Schauer, C.; Pöschl, U.; Plass-Dülmer, C.; Berresheim, H.

    2008-02-01

    Detailed investigations of the chemical and microphysical properties of rural continental aerosols were performed during the HAZE2002 experiment, which was conducted in May 2002 at the Meteorological Observatory Hohenpeissenberg (DWD) in Southern Germany. Online measurements included: Size-resolved chemical composition of submicron particles; total particle number concentrations and size distributions over the diameter range of 3 nm to 9 μm; gas-phase concentration of monoterpenes, CO, O3, OH, and H2SO4. Filter sampling and offline analytical techniques were used to determine: Fine particle mass (PM2.5), organic, elemental and total carbon in PM2.5 (OC2.5, EC2.5, TC2.5), and selected organic compounds (dicarboxylic acids, polycyclic aromatic hydrocarbons, proteins). Overall, the non-refractory components of submicron particles detected by aerosol mass spectrometry (PM1, 6.6±5.4 μg m-3, arithmetic mean and standard deviation) accounted for ~62% of PM2.5 determined by filter gravimetry (10.6±4.7 μg m-3). The relative proportions of non-refractory submicron particle components were: (23±39)% ammonium nitrate, (27±23)% ammonium sulfate, and (50±40)% organics (OM1). OM1 was closely correlated with PM1 (r2=0.9) indicating a near-constant ratio of non-refractory organics and inorganics. The average ratio of OM1 to OC2.5 was 2.1±1.4, indicating a high proportion of heteroelements in the organic fraction of the sampled rural aerosol. This is consistent with the high ratio of oxygenated organic aerosol (OOA) over hydrocarbon-like organic aerosol (HOA) inferred from the AMS results (4:1), and also with the high abundance of proteins (~3%) indicating a high proportion of primary biological material (~30%) in PM2.5. This finding was confirmed by low abundance of PAHs (<1 ng m-3) and EC (<1 μg m-3) in PM2.5 and detection of several secondary organic aerosol compounds (dicarboxylic acids) and their precursors (monoterpenes). New particle formation was observed almost

  17. Experimental Assessment of Collection Efficiency of Submicron Aerosol Particles by Cloud Droplets

    NASA Astrophysics Data System (ADS)

    Huang, Y.; Ardon-Dryer, K.; Cziczo, D. J.

    2013-12-01

    The interplay between aerosol particles and water droplets in the atmosphere, especially in clouds, influences both aerosol and cloud properties. The major uncertainty in our understanding of climate arises in the indirect effect of aerosol and their ability to impact cloud formation and consequently alter the global radiative balance. The collision between a water droplet and aerosol particles that results in coalescence is termed 'collection' or 'coagulation'. Coagulation can lead to aerosol removal from the atmosphere or induce ice nucleation via contact freezing at temperatures below 0 C. Theoretical studies have shown that for aerosol particles smaller than 0.1 micrometers, Brownian motion is important, and for particles with diameters larger than 1 micrometer, inertial force dominates. There is a collection efficiency minimum for particles between 0.1-2 micrometers, called the 'Greenfield Gap'. Experimental efforts, however, have been limited to very large drizzle and rain drops until recently, and constrained parameters necessary to describe particle collection efficiency by cloud droplets have not been available. One reason is that laboratory setups that allow for coagulation to be observed on a single-particle basis have been lacking. Collection efficiency is also an important parameter for studying and assessing contact ice nucleation. Contact ice nucleation is currently the least understood ice nucleation mechanism and can be potentially important for mixed-phase cloud formation. The significance of experimentally assessing collection efficiency is therefore two-fold: to first understand the frequency of contacts and to then understand the fraction that lead to ice nucleation. We have constructed the MIT-Contact Freezing Chamber (MIT-CFC) to study collection efficiency of submicron aerosol particles by cloud droplets and contact freezing. A stream of 30-micron cloud droplets fall freely into the chamber and collide with aerosol particles. The outflow

  18. Space-borne Observations of Aerosols

    NASA Astrophysics Data System (ADS)

    Kaufman, Y. J.; Tanre, D.; Coakley, J. A.; Fraser, R. S.

    2005-12-01

    As early as 1963, photographs of the twilight horizon from the Vostok-6 spaceship were used by G. V. Rozenberg and V. V. Nikolaeva-Tereshkova to derive profiles of stratospheric aerosols. The launch of the ATS III satellite in 1967 sparked interest in using satellites to observe aerosol emission, transport, and their effects on climate, precipitation and health. The first use of autonomous satellites in aerosol research appears to be by Toby Carlson and Joe Prospero who tracked dust from the Sahara to the Americas in the early `70s using ATS III images. The launch of the calibrated Landsat instrument in 1972 allowed Bob Fraser to perform quantitative analyses of dust column concentrations for individual scenes. GOES launched in 1975 provided hourly data that allowed Walter Lyons and J.C. Dooley in the late 70's to report on the transport of sulfate air pollution which was later followed by estimates of the export of sulfate aerosol from the US to the Atlantic Ocean. With the launch of SAGE in 1979, Pat McCormick and co-workers began long term observations of statospheric aerosols. The launch of TIROS(N) and the AVHRR in 1979 marked the start of concerted efforts by Larry Stowe and his colleagues to produce operationally an aerosol product over oceans from the NOAA polar orbiting satellite. With the launch of the Earth Radiation Budget Experiment scanners in the late 1980's, Sundar Christopher and his colleagues began linking AVHRR-derived aerosol burdens to their effects on the Earth's radiation budget. A remarkable aspect of this early work is that instruments like the AVHRR, Landsat, and GOES imager were not originally designed to perform quantitative estimates of aerosol properties. In fact, corrections for the effects of aerosols in determining ocean reflectances implemented primarily through the work of Howard Gordon, facilitated much improved pictures of chlorophyll in the upper oceans than had been hoped for from CZCS data collected in the late 70's. This

  19. Aerosol properties in Titan's upper atmosphere from UVIS airglow observations

    NASA Astrophysics Data System (ADS)

    Lavvas, Panayotis; Koskinen, Tommi; Royer, Emilie; Rannou, Pascal; West, Robert A.

    2015-11-01

    Multiple Cassini observations reveal that the abundant aerosol particles in Titan's atmosphere are formed at high altitudes, particularly in the thermosphere [1]. They subsequently fall towards the lower atmosphere, and in their path, their size, shape, and population change in reflection to the variable atmospheric conditions.Although multiple observations can help us retrieve information for the aerosol properties in the lower atmosphere [2], we have limited knowledge for their properties in the altitude range between their formation region in the thermosphere, and the upper region of the main haze layer. UVIS is one of a few instruments that can probe this part of the atmosphere and allow for the retrieval of the aerosol properties.Here we analyze observations of atmospheric airglow that demonstrate the signature of N2 emissions and light scattering from aerosol particles, at different altitudes above 500 km [3]. We fit these observations with a combined model of N2 airglow [4] and atmospheric scattering by gases and aerosols that allows us to separate the pure scattering component and retrieve the aerosol size (distribution) and density. We particularly focus on observations from the T32 flyby that probed high southern latitudes in 2007 and combine good altitude resolution with high signal to noise ratio. We combine these with observations at different phase angles and observing geometry conditions (nadir vs. limb) in order to set better constraints on the aerosol properties.Our preliminary results demonstrate an increase in the average particle size with decreasing altitude in the atmosphere, from about 10 nm at 800 km to ~50 nm at 500 km, and an extinction profile at 185 nm wavelength, similar to the profile derive from UVIS occultation measurements at lower latitudes [5].[1] Lavvas et al. 2013. PNAS, doi/10.1073/pnas.1217059110, and references therein.[2] Tomasko et al. 2008, PSS, 56, p.669; Bellucci et al. 2009, Icarus 201, p.198[3] Ajello et al. 2008, GRL

  20. 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

  1. Hydrolysis of organonitrate functional groups in aerosol particles

    SciTech Connect

    Liu, Shang; Shilling, John E.; Song, Chen; Hiranuma, Naruki; Zaveri, Rahul A.; Russell, Lynn M.

    2012-10-19

    Organonitrate (ON) groups are important substituents in secondary organic aerosols. Model simulations and laboratory studies indicate a large fraction of ON groups in aerosol particles, but much lower quantities are observed in the atmosphere. Hydrolysis of ON groups in aerosol particles has been proposed recently. To test this hypothesis, we simulated formation of ON molecules in a reaction chamber under a wide range of relative humidity (0% to 90%). The mass fraction of ON groups (5% to 20% for high-NOx experiments) consistently decreased with increasing relative humidity, which was best explained by hydrolysis of ON groups at a rate of 4 day-1 (lifetime of 6 hours) for reactions under relative humidity greater than 20%. In addition, we found that secondary nitrogen-containing molecules absorb light, with greater absorption under dry and high-NOx conditions. This work provides the first evidence for particle-phase hydrolysis of ON groups, a process that could substantially reduce ON group concentration in the atmosphere.

  2. 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

  3. An amorphous solid state of biogenic secondary organic aerosol particles.

    PubMed

    Virtanen, Annele; Joutsensaari, Jorma; Koop, Thomas; Kannosto, Jonna; Yli-Pirilä, Pasi; Leskinen, Jani; Mäkelä, Jyrki M; Holopainen, Jarmo K; Pöschl, Ulrich; Kulmala, Markku; Worsnop, Douglas R; Laaksonen, Ari

    2010-10-14

    Secondary organic aerosol (SOA) particles are formed in the atmosphere from condensable oxidation products of anthropogenic and biogenic volatile organic compounds (VOCs). On a global scale, biogenic VOCs account for about 90% of VOC emissions and of SOA formation (90 billion kilograms of carbon per year). SOA particles can scatter radiation and act as cloud condensation or ice nuclei, and thereby influence the Earth's radiation balance and climate. They consist of a myriad of different compounds with varying physicochemical properties, and little information is available on the phase state of SOA particles. Gas-particle partitioning models usually assume that SOA particles are liquid, but here we present experimental evidence that they can be solid under ambient conditions. We investigated biogenic SOA particles formed from oxidation products of VOCs in plant chamber experiments and in boreal forests within a few hours after atmospheric nucleation events. On the basis of observed particle bouncing in an aerosol impactor and of electron microscopy we conclude that biogenic SOA particles can adopt an amorphous solid-most probably glassy-state. This amorphous solid state should provoke a rethinking of SOA processes because it may influence the partitioning of semi-volatile compounds, reduce the rate of heterogeneous chemical reactions, affect the particles' ability to accommodate water and act as cloud condensation or ice nuclei, and change the atmospheric lifetime of the particles. Thus, the results of this study challenge traditional views of the kinetics and thermodynamics of SOA formation and transformation in the atmosphere and their implications for air quality and climate. PMID:20944744

  4. Indirect estimation of absorption properties for fine aerosol particles using AATSR observations: a case study of wildfires in Russia in 2010

    NASA Astrophysics Data System (ADS)

    Rodriguez, E.; Kolmonen, P.; Virtanen, T. H.; Sogacheva, L.; Sundstrom, A.-M.; de Leeuw, G.

    2015-08-01

    The Advanced Along-Track Scanning Radiometer (AATSR) on board the ENVISAT satellite is used to study aerosol properties. The retrieval of aerosol properties from satellite data is based on the optimized fit of simulated and measured reflectances at the top of the atmosphere (TOA). The simulations are made using a radiative transfer model with a variety of representative aerosol properties. The retrieval process utilizes a combination of four aerosol components, each of which is defined by their (lognormal) size distribution and a complex refractive index: a weakly and a strongly absorbing fine-mode component, coarse mode sea salt aerosol and coarse mode desert dust aerosol). These components are externally mixed to provide the aerosol model which in turn is used to calculate the aerosol optical depth (AOD). In the AATSR aerosol retrieval algorithm, the mixing of these components is decided by minimizing the error function given by the sum of the differences between measured and calculated path radiances at 3-4 wavelengths, where the path radiances are varied by varying the aerosol component mixing ratios. The continuous variation of the fine-mode components allows for the continuous variation of the fine-mode aerosol absorption. Assuming that the correct aerosol model (i.e. the correct mixing fractions of the four components) is selected during the retrieval process, also other aerosol properties could be computed such as the single scattering albedo (SSA). Implications of this assumption regarding the ratio of the weakly/strongly absorbing fine-mode fraction are investigated in this paper by evaluating the validity of the SSA thus obtained. The SSA is indirectly estimated for aerosol plumes with moderate-to-high AOD resulting from wildfires in Russia in the summer of 2010. Together with the AOD, the SSA provides the aerosol absorbing optical depth (AAOD). The results are compared with AERONET data, i.e. AOD level 2.0 and SSA and AAOD inversion products. The RMSE

  5. Synergic use of TOMS and Aeronet Observations for Characterization of Aerosol Absorption

    NASA Technical Reports Server (NTRS)

    Torres, O.; Bhartia, P. K.; Dubovik, O.; Holben, B.; Siniuk, A.

    2003-01-01

    The role of aerosol absorption on the radiative transfer balance of the earth-atmosphere system is one of the largest sources of uncertainty in the analysis of global climate change. Global measurements of aerosol single scattering albedo are, therefore, necessary to properly assess the radiative forcing effect of aerosols. Remote sensing of aerosol absorption is currently carried out using both ground (Aerosol Robotic Network) and space (Total Ozone Mapping Spectrometer) based observations. The satellite technique uses measurements of backscattered near ultraviolet radiation. Carbonaceous aerosols, resulting from the combustion of biomass, are one of the most predominant absorbing aerosol types in the atmosphere. In this presentation, TOMS and AERONET retrievals of single scattering albedo of carbonaceous aerosols, are compared for different environmental conditions: agriculture related biomass burning in South America and Africa and peat fires in Eastern Europe. The AERONET and TOMS derived aerosol absorption information are in good quantitative agreement. The most absorbing smoke is detected over the African Savanna. Aerosol absorption over the Brazilian rain forest is less absorbing. Absorption by aerosol particles resulting from peat fires in Eastern Europe is weaker than the absorption measured in Africa and South America. This analysis shows that the near UV satellite method of aerosol absorption characterization has the sensitivity to distinguish different levels of aerosol absorption. The analysis of the combined AERONET-TOMS observations shows a high degree of synergy between satellite and ground based observations.

  6. Observation of hydration of single, modified carbon aerosols

    NASA Technical Reports Server (NTRS)

    Wyslouzil, B. E.; Carleton, K. L.; Sonnenfroh, D. M.; Rawlins, W. T.; Arnold, S.

    1994-01-01

    We have compared the hydration behavior of single carbon particles that have been treated by exposure to gaseous H2SO4 with that of untreated particles. Untreated carbon particles did not hydrate as the relative humidity varied from 0 to 80% at 23 C. In contrast, treated particles hydrated under subsaturation conditions; mass increases of up to 30% were observed. The mass increase is consistent with sulfuric acid equilibration with the ambient relative humidity in the presence of inert carbon. For the samples studied, the average amount of absorbed acid was 14% +/- 6% by weight, which corresponds to a surface coverage of approximately 0.1 monolayer. The mass fraction of surface-absorbed acid is comparable to the soluble mass fraction observed by Whitefield et al. (1993) in jet aircraft engine aerosols. Estimates indicate this mass fraction corresponds to 0.1% of the available SO2 exiting an aircraft engine ending up as H2SO4 on the carbon aerosol. If this heterogeneous process occurs early enough in the exhaust plume, it may compete with homogeneous nucleation as a mechanism for producing sulfuric acid rich aerosols.

  7. Observation of hydration of single, modified carbon aerosols

    NASA Astrophysics Data System (ADS)

    Wyslouzil, B. E.; Carleton, K. L.; Sonnenfroh, D. M.; Rawlins, W. T.; Arnold, S.

    1994-09-01

    We have compared the hydration behavior of single carbon particles that have been treated by exposure to gaseous H2SO4 with that of untreated particles. Untreated carbon particles did not hydrate as the relative humidity varied from 0 to 80% at 23°C. In contrast, treated particles hydrated under subsaturation conditions; mass increases of up to 30% were observed. The mass increase is consistent with sulfuric acid equilibration with the ambient relative humidity in the presence of inert carbon. For the samples studied, the average amount of adsorbed acid was 14% ± 6% by weight, which corresponds to a surface coverage of ˜0.1 monolayer. The mass fraction of surface-adsorbed acid is comparable to the soluble mass fraction observed by Whitefield et al. (1993) in jet aircraft engine aerosols. Estimates indicate this mass fraction corresponds to 0.1% of the available SO2 exiting an aircraft engine ending up as H2SO4 on the carbon aerosol. If this heterogeneous process occurs early enough in the exhaust plume, it may compete with homogeneous nucleation as a mechanism for producing sulfuric acid rich aerosols.

  8. 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.

  9. The rate of equilibration of viscous aerosol particles

    NASA Astrophysics Data System (ADS)

    O'Meara, Simon; Topping, David O.; McFiggans, Gordon

    2016-04-01

    The proximity of atmospheric aerosol particles to equilibrium with their surrounding condensable vapours can substantially impact their transformations, fate and impacts and is the subject of vibrant research activity. In this study we first compare equilibration timescales estimated by three different models for diffusion through aerosol particles to assess any sensitivity to choice of model framework. Equilibration times for diffusion coefficients with varying dependencies on composition are compared for the first time. We show that even under large changes in the saturation ratio of a semi-volatile component (es) of 1-90 % predicted equilibration timescales are in agreement, including when diffusion coefficients vary with composition. For condensing water and a diffusion coefficient dependent on composition, a plasticising effect is observed, leading to a decreased estimated equilibration time with increasing final es. Above 60 % final es maximum equilibration times of around 1 s are estimated for comparatively large particles (10 µm) containing a relatively low diffusivity component (1 × 10-25 m2 s-1 in pure form). This, as well as other results here, questions whether particle-phase diffusion through water-soluble particles can limit hygroscopic growth in the ambient atmosphere. In the second part of this study, we explore sensitivities associated with the use of particle radius measurements to infer diffusion coefficient dependencies on composition using a diffusion model. Given quantified similarities between models used in this study, our results confirm considerations that must be taken into account when designing such experiments. Although quantitative agreement of equilibration timescales between models is found, further work is necessary to determine their suitability for assessing atmospheric impacts, such as their inclusion in polydisperse aerosol simulations.

  10. 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

    particles with r(sub m) less than 0.2 microns and coarse paritcles with r(sub m) greater than 0.7 microns. The 'window' in the tropospheric aerosol in this radius range was used to observe a stable stratospheric aerosol in 1992, with r(sub m) approximately 0.5 microns. A combination of such optical thickness and sky measurements can be used to assess the direct forcing and the climatic impact of aerosol. Systematic inversion for the key aerosol types (sulfates, smoke, dust, and maritime aerosol) of the size distribution and phase function can give the relationship between the aerosol physical and optical properties that can be used to compute the radiative forcing. This forcing can be validated in dedicated field experiments.

  11. Reactive uptake of HOCl to laboratory generated sea salt particles and nascent sea-spray aerosol

    NASA Astrophysics Data System (ADS)

    Campbell, N. R.; Ryder, O. S.; Bertram, T. H.

    2013-12-01

    Field observations suggest that the reactive uptake of HOCl on marine aerosol particles is an important source of chlorine radicals, particularly under low NOx conditions. However to date, laboratory measurements disagree on the magnitude of the reactive uptake coefficient for HOCl by a factor of 5 (γ(HOCl) ranges between 0.0004 and 0.0018), and there are no measurements of γ(HOCl) on nascent sea-spray aerosol. Here, we present measurements of the reactive uptake of HOCl to laboratory generated sodium chloride and sea-spray aerosol particles generated in a novel Marine Aerosol Reference Tank (MART), coupled to an entrained aerosol flow reactor and Chemical Ionization Mass Spectrometer (CIMS). Measurements of γ(HOCl) retrieved here are compared against those in the literature, and the role of organic coatings on nascent sea-spray aerosol is explored.

  12. Organic aggregate formation in aerosols and its impact on the physicochemical properties of atmospheric particles

    NASA Astrophysics Data System (ADS)

    Tabazadeh, Azadeh

    Fatty acid salts and "humic" materials, found in abundance in atmospheric particles, are both anionic surfactants. Such materials are known to form organic aggregates or colloids in solution at very low aqueous concentrations. In a marine aerosol, micelle aggregates can form at a low fatty acid salt molality of ˜10 -3 m. In other types of atmospheric particles, such as biomass burning, biogenic, soil dust, and urban aerosols, "humic-like" materials exist in sufficient quantities to form micelle-like aggregates in solution. I show micelle formation limits the ability of surface-active organics in aerosols to reduce the surface tension of an atmospheric particle beyond about 10 dyne cm -1. A general phase diagram is presented for anionic surfactants to explain how surface-active organics can change the water uptake properties of atmospheric aerosols. Briefly such molecules can enhance and reduce water uptake by atmospheric aerosols at dry and humid conditions, respectively. This finding is consistent with a number of unexplained field and laboratory observations. Dry electron microscope images of atmospheric particles often indicate that organics may coat the surface of particles in the atmosphere. The surfactant phase diagram is used to trace the particle path back to ambient conditions in order to determine whether such coatings can exist on wet ambient aerosols. Finally, I qualitatively highlight how organic aggregate formation in aerosols may change the optical properties and chemical reactivity of atmospheric particles.

  13. Stratospheric aerosols on Jupiter from Cassini observations

    NASA Astrophysics Data System (ADS)

    Zhang, X.; West, R. A.; Banfield, D.; Yung, Y. L.

    2013-09-01

    We retrieved global distributions and optical properties of stratospheric aerosols on Jupiter from ground-based NIR spectra and multiple-phase-angle images from Cassini Imaging Science Subsystem (ISS). A high-latitude haze layer is located at ∼10-20 mbar, higher than in the middle and low latitudes (∼50 mbar). Compact sub-micron particles are mainly located in the low latitudes between 40°S and 25°N with the particle radius between 0.2 and 0.5 μm. The rest of the stratosphere is covered by the particles known as fractal aggregates. In the nominal case with the imaginary part of the UV refractive index 0.02, the fractal aggregates are composed of about a thousand 10-nm-size monomers. The column density of the aerosols at pressure less than 100 mbar ranges from ∼107 cm-2 at low latitudes to ∼109 cm-2 at high latitudes. The mass loading of aerosols in the stratosphere is ∼10-6 g cm-2 at low latitudes to ∼10-4 g cm-2 in the high latitudes. Multiple solutions due to the uncertainty of the imaginary part of the refractive index are discussed. The stratospheric haze optical depths increase from ∼0.03 at low latitudes to about a few at high latitudes in the UV wavelength (∼0.26 μm), and from ∼0.03 at low latitudes to ∼0.1 at high latitudes in the NIR wavelength (∼0.9 μm).

  14. 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

  15. Retrieval of Aerosol Optical Depth Above Clouds from OMI Observations: Sensitivity Analysis, Case Studies

    NASA Technical Reports Server (NTRS)

    Torres, O.; Jethva, H.; Bhartia, P. K.

    2012-01-01

    A large fraction of the atmospheric aerosol load reaching the free troposphere is frequently located above low clouds. Most commonly observed aerosols above clouds are carbonaceous particles generally associated with biomass burning and boreal forest fires, and mineral aerosols originated in arid and semi-arid regions and transported across large distances, often above clouds. Because these aerosols absorb solar radiation, their role in the radiative transfer balance of the earth atmosphere system is especially important. The generally negative (cooling) top of the atmosphere direct effect of absorbing aerosols, may turn into warming when the light-absorbing particles are located above clouds. The actual effect depends on the aerosol load and the single scattering albedo, and on the geometric cloud fraction. In spite of its potential significance, the role of aerosols above clouds is not adequately accounted for in the assessment of aerosol radiative forcing effects due to the lack of measurements. In this paper we discuss the basis of a simple technique that uses near-UV observations to simultaneously derive the optical depth of both the aerosol layer and the underlying cloud for overcast conditions. The two-parameter retrieval method described here makes use of the UV aerosol index and reflectance measurements at 388 nm. A detailed sensitivity analysis indicates that the measured radiances depend mainly on the aerosol absorption exponent and aerosol-cloud separation. The technique was applied to above-cloud aerosol events over the Southern Atlantic Ocean yielding realistic results as indicated by indirect evaluation methods. An error analysis indicates that for typical overcast cloudy conditions and aerosol loads, the aerosol optical depth can be retrieved with an accuracy of approximately 54% whereas the cloud optical depth can be derived within 17% of the true value.

  16. Observed high aerosol loading during dust events in Delhi

    NASA Astrophysics Data System (ADS)

    Singh, Khem; Aggarwal, Shankar G.; Jha, Arvind K.; Singh, Nahar; Soni, Daya; Gupta, Prabhat K.

    2012-07-01

    The present study reports aerosol mass loadings and their chemical property during integrated campaign for aerosol and radiation budget (ICARB) in the month of March to May 2006, at NPL, New Delhi. The Thar Desert in Rajasthan is located on the western end of India and south-west of Delhi is hot and arid region with intense aeolian activity and transport of aerosol by the prevailing southwest-west summer wind. Several dust episodes were observed in Delhi during summer 2006. The dust storm peaked on 29th April, 1 ^{st} and 8 ^{th} May 2006, with very high suspended particulate matter (SPM) concentrations 1986μg/m ^{3}, 1735μg/m ^{3} and 1511μg/m ^{3}, respectively. The average concentration of SPM in the month of March, April and May 2006 was 338 μg/m ^{3}, 698 μg/m ^{3} and 732 μg/m ^{3}, respectively. The SPM filter samples were analysed for water-soluble major cations (Na ^{+}, Ca ^{2+}, K ^{+}, and Mg ^{2+}) by atomic absorption spectrophotometry (AAS). Na ^{+} and Ca ^{2+} contribute about 54% and 20%, respectively of the total identified cation mass, indicating that they were most abundant cations. Strong correlations between Na ^{+}, Ca ^{2+}, K ^{+}, and Mg ^{2+} suggest their soil and dust origin. Such a high particle concentration observed during dust events may also be useful for study the effect of these aerosols on communication medium.

  17. 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.

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

    SciTech Connect

    Davidovits, Paul

    2015-10-20

    Aerosols containing black carbon (and some specific types of organic particulate matter) directly absorb incoming light, heating the atmosphere. In addition, all aerosol particles backscatter solar light, leading to a net-cooling effect. Indirect effects involve hydrophilic aerosols, which serve as cloud condensation nuclei (CCN) that affect cloud cover and cloud stability, impacting both atmospheric radiation balance and precipitation patterns. At night, all clouds produce local warming, but overall clouds exert a net-cooling effect on the Earth. The effect of aerosol radiative forcing on climate may be as large as that of the greenhouse gases, but predominantly opposite in sign and much more uncertain. The uncertainties in the representation of aerosol interactions in climate models makes it problematic to use model projections to guide energy policy. The objective of our program is to reduce the uncertainties in the aerosol radiative forcing in the two areas highlighted in the ASR Science and Program Plan. That is, (1) addressing the direct effect by correlating particle chemistry and morphology with particle optical properties (i.e. absorption, scattering, extinction), and (2) addressing the indirect effect by correlating particle hygroscopicity and CCN activity with particle size, chemistry, and morphology. In this connection we are systematically studying particle formation, oxidation, and the effects of particle coating. The work is specifically focused on carbonaceous particles where the uncertainties in the climate relevant properties are the highest. The ongoing work consists of laboratory experiments and related instrument inter-comparison studies both coordinated with field and modeling studies, with the aim of providing reliable data to represent aerosol processes in climate models. The work is performed in the aerosol laboratory at Boston College. At the center of our laboratory setup are two main sources for the production of aerosol particles: (a

  19. Nuclear microprobe analysis and source apportionment of individual atmospheric aerosol particles

    NASA Astrophysics Data System (ADS)

    Artaxo, Paulo; Rabello, Marta L. C.; Watt, Frank; Grime, Geoff; Swietlicki, Erik

    1993-04-01

    In atmospheric aerosol research, one key issue is to determine the sources of the airborne particles. Bulk PIXE analysis coupled with receptor modeling provides a useful, but limited view of the aerosol sources influencing one particular site or sample. The scanning nuclear microprobe (SNM) technique is a microanalytical technique that gives unique information on individual aerosol particles. In the SNM analyses a 1.0 μm size 2.4 MeV proton beam from the Oxford SNM was used. The trace elements with Z > 11 were measured by the particle induced X-ray emission (PIXE) method with detection limits in the 1-10 ppm range. Carbon, nitrogen and oxygen are measured simultaneously using Rutherford backscattering spectrometry (RBS). Atmospheric aerosol particles were collected at the Brazilian Antarctic Station and at biomass burning sites in the Amazon basin tropical rain forest in Brazil. In the Antarctic samples, the sea-salt aerosol particles were clearly predominating, with NaCl and CaSO 4 as major compounds with several trace elements as Al, Si, P, K, Mn, Fe, Ni, Cu, Zn, Br, Sr, and Pb. Factor analysis of the elemental data showed the presence of four components: 1) soil dust particles; 2) NaCl particles; 3) CaSO 4 with Sr; and 4) Br and Mg. Strontium, observed at 20-100 ppm levels, was always present in the CaSO 4 particles. The hierarchical cluster procedure gave results similar to the ones obtained through factor analysis. For the tropical rain forest biomass burning aerosol emissions, biogenic particles with a high organic content dominate the particle population, while K, P, Ca, Mg, Zn, and Si are the dominant elements. Zinc at 10-200 ppm is present in biogenic particles rich in P and K. The quantitative aspects and excellent detection limits make SNM analysis of individual aerosol particles a very powerful analytical tool.

  20. Modelled and observed changes in aerosols and surface solar radiation over Europe between 1960 and 2009

    NASA Astrophysics Data System (ADS)

    Turnock, S. T.; Spracklen, D. V.; Carslaw, K. S.; Mann, G. W.; Woodhouse, M. T.; Forster, P. M.; Haywood, J.; Johnson, C. E.; Dalvi, M.; Bellouin, N.; Sanchez-Lorenzo, A.

    2015-08-01

    Substantial changes in anthropogenic aerosols and precursor gas emissions have occurred over recent decades due to the implementation of air pollution control legislation and economic growth. The response of atmospheric aerosols to these changes and the impact on climate are poorly constrained, particularly in studies using detailed aerosol chemistry-climate models. Here we compare the HadGEM3-UKCA (Hadley Centre Global Environment Model-United Kingdom Chemistry and Aerosols) coupled chemistry-climate model for the period 1960-2009 against extensive ground-based observations of sulfate aerosol mass (1978-2009), total suspended particle matter (SPM, 1978-1998), PM10 (1997-2009), aerosol optical depth (AOD, 2000-2009), aerosol size distributions (2008-2009) and surface solar radiation (SSR, 1960-2009) over Europe. The model underestimates observed sulfate aerosol mass (normalised mean bias factor (NMBF) = -0.4), SPM (NMBF = -0.9), PM10 (NMBF = -0.2), aerosol number concentrations (N30 NMBF = -0.85; N50 NMBF = -0.65; and N100 NMBF = -0.96) and AOD (NMBF = -0.01) but slightly overpredicts SSR (NMBF = 0.02). Trends in aerosol over the observational period are well simulated by the model, with observed (simulated) changes in sulfate of -68 % (-78 %), SPM of -42 % (-20 %), PM10 of -9 % (-8 %) and AOD of -11 % (-14 %). Discrepancies in the magnitude of simulated aerosol mass do not affect the ability of the model to reproduce the observed SSR trends. The positive change in observed European SSR (5 %) during 1990-2009 ("brightening") is better reproduced by the model when aerosol radiative effects (ARE) are included (3 %), compared to simulations where ARE are excluded (0.2 %). The simulated top-of-the-atmosphere aerosol radiative forcing over Europe under all-sky conditions increased by > 3.0 W m-2 during the period 1970-2009 in response to changes in anthropogenic emissions and aerosol concentrations.

  1. Inkjet aerosol generator as monodisperse particle number standard

    NASA Astrophysics Data System (ADS)

    Iida, Kenjiro; Sakurai, Hiromu; Ehara, Kensei

    2013-05-01

    Inkjet technology can be applied to generate highly monodisperse aerosol particles in micrometer range at a precisely controlled rate. AIST has been developing an inkjet aerosol generator (AIST-IAG), and the device will soon become the secondary measurement standard for aerosol particle number concentration in 0.35 μm to 10 μm range. The AIST-IAG can generate both solid and liquid particles consisting of water-soluble ionic compounds. We first report the characteristics of the particle sizes of the generated particles. The full width half maximum of the particle size distribution is about 2 percent, and the particle diameter of the IAG particles was calibrated as a function of the particle mass within 0.6-10 μm range using polystyrene latex sphere as reference material. Then we report the capability of the AIST-IAG as the particle number standard. The particle generation efficiency ηIAG was defined as the number of aerosol particles exiting from the AIST-IAG divided by the rate of the droplet generation, and the values of ηIAG within 0.35-10 μm is essentially 100%, and the 95% confidence interval of the values is less than 1%. The result strongly supports that the AISTIAG can be used to calibrate the counting efficiency of the optical particle counters in submicrometer to micrometer range.

  2. Nature and evolution of ultrafine aerosol particles in the atmosphere

    NASA Astrophysics Data System (ADS)

    Smirnov, V. V.

    2006-12-01

    Results of experimental and theoretical studies of a poorly understood phenomenon, an intense emission of ultrafine (nanometer) aerosols (ENA), are reviewed. In the English-language literature, this phenomenon is commonly referred to as a nucleation burst. ENA events have been observed on all the continents and throughout the depth of the troposphere, with the number of corresponding publications growing steadily. Intense and long-lasting ENA events have been studied more or less comprehensively and in full detail for Northern Europe, with 60 to 70% of observations taken in a forest area in the presence of snow cover and 10 to 20% in coastal marine areas. Most often, ENA events occur during spring and fall, with 95% of cases in the daytime and under sunny calm conditions, typical of anticyclones. In ENA events, the concentration of nanoparticles initially grows rapidly to values of 103-105 cm-3. One or two hours later, the so-called nuclei fraction with diameters D = 3-15 nm is produced. The appearance of the Aitken fraction D = 20-80 nm and the enlargement of aerosol particles inside the accumulation fraction D = 80-200 nm may occur during the following 4-6 h. Thus, the cycle of formation and growth of atmospheric aerosol particles in the size range from a few to hundreds of nanometers is reproduced over 6-8 h. A specific synoptic feature of ENA events over land is that they occur when the polar air is transported to measuring sites and the temperature difference between day and light is large. During ENA periods, the formation rate of condensation nuclei with a diameter of 100 nm increases 10-to 100-fold. Important factors of ENA genesis are the “aerosol” and “electric” states of the atmosphere. More intense ENA events occur at low concentrations of background aerosols in the presence of atmospheric ions of medium mobility with D = 2-3 nm. The international experiments ACE 1 and 2, BIOFOR 1, 2, and 3, ESUP 2000, QUEST, etc., have not yet provided any

  3. What we can Learn About Aerosols from EOS-MISR Multi-Angle Remote Sensing Observations

    NASA Technical Reports Server (NTRS)

    Kahn, Ralph

    2000-01-01

    Multiangle, multispectral remote sensing observations, such as those anticipated from the Earth Observing System (EOS) Multiangle Imaging SpectroRadiometer (MISR), promise to significantly improve our ability to constrain aerosol properties from space. Recent advances in modeling the Earth's climate have brought us to a point where the contributions made by aerosols to the global radiation budget noticeably affect the results. Knowledge of both aerosol optical depth and the microphysical properties of particles is needed to adequately model aerosol effects. This talk explores the ability of multiangle, multi-spectral remote sensing observations anticipated from the EOS MISR instrument, to retrieve aerosol optical depth and information about mixes of particle types, globally, at 17.6 km spatial resolution. The instrument is scheduled for launch into a 10:30 AM, sun-synchronous polar orbit in 1999.

  4. 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...

  5. 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.

  6. 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.

  7. 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.

  8. Observational insights into aerosol formation from isoprene.

    PubMed

    Worton, David R; Surratt, Jason D; Lafranchi, Brian W; Chan, Arthur W H; Zhao, Yunliang; Weber, Robin J; Park, Jeong-Hoo; Gilman, Jessica B; de Gouw, Joost; Park, Changhyoun; Schade, Gunnar; Beaver, Melinda; Clair, Jason M St; Crounse, John; Wennberg, Paul; Wolfe, Glenn M; Harrold, Sara; Thornton, Joel A; Farmer, Delphine K; Docherty, Kenneth S; Cubison, Michael J; Jimenez, Jose-Luis; Frossard, Amanda A; Russell, Lynn M; Kristensen, Kasper; Glasius, Marianne; Mao, Jingqiu; Ren, Xinrong; Brune, William; Browne, Eleanor C; Pusede, Sally E; Cohen, Ronald C; Seinfeld, John H; Goldstein, Allen H

    2013-10-15

    Atmospheric photooxidation of isoprene is an important source of secondary organic aerosol (SOA) and there is increasing evidence that anthropogenic oxidant emissions can enhance this SOA formation. In this work, we use ambient observations of organosulfates formed from isoprene epoxydiols (IEPOX) and methacrylic acid epoxide (MAE) and a broad suite of chemical measurements to investigate the relative importance of nitrogen oxide (NO/NO2) and hydroperoxyl (HO2) SOA formation pathways from isoprene at a forested site in California. In contrast to IEPOX, the calculated production rate of MAE was observed to be independent of temperature. This is the result of the very fast thermolysis of MPAN at high temperatures that affects the distribution of the MPAN reservoir (MPAN / MPA radical) reducing the fraction that can react with OH to form MAE and subsequently SOA (F(MAE formation)). The strong temperature dependence of F(MAE formation) helps to explain our observations of similar concentrations of IEPOX-derived organosulfates (IEPOX-OS; ~1 ng m(-3)) and MAE-derived organosulfates (MAE-OS; ~1 ng m(-3)) under cooler conditions (lower isoprene concentrations) and much higher IEPOX-OS (~20 ng m(-3)) relative to MAE-OS (<0.0005 ng m(-3)) at higher temperatures (higher isoprene concentrations). A kinetic model of IEPOX and MAE loss showed that MAE forms 10-100 times more ring-opening products than IEPOX and that both are strongly dependent on aerosol water content when aerosol pH is constant. However, the higher fraction of MAE ring opening products does not compensate for the lower MAE production under warmer conditions (higher isoprene concentrations) resulting in lower formation of MAE-derived products relative to IEPOX at the surface. In regions of high NOx, high isoprene emissions and strong vertical mixing the slower MPAN thermolysis rate aloft could increase the fraction of MPAN that forms MAE resulting in a vertically varying isoprene SOA source. PMID:24004194

  9. Observed changes in aerosol physical and optical properties before and after precipitation events

    NASA Astrophysics Data System (ADS)

    Li, Xingmin; Dong, Yan; Dong, Zipeng; Du, Chuanli; Chen, Chuang

    2016-08-01

    Precipitation scavenging of aerosol particles is an important removal process in the atmosphere that can change aerosol physical and optical properties. This paper analyzes the changes in aerosol physical and optical properties before and after four rain events using in situ observations of mass concentration, number concentration, particle size distribution, scattering and absorption coefficients of aerosols in June and July 2013 at the Xianghe comprehensive atmospheric observation station in China. The results show the effect of rain scavenging is related to the rain intensity and duration, the wind speed and direction. During the rain events, the temporal variation of aerosol number concentration was consistent with the variation in mass concentration, but their size-resolved scavenging ratios were different. After the rain events, the increase in aerosol mass concentration began with an increase in particles with diameter <0.8 μm [measured using an aerodynamic particle sizer (APS)], and fine particles with diameter <0.1 μm [measured using a scanning mobility particle sizer (SMPS)]. Rainfall was most efficient at removing particles with diameter ~0.6 μm and greater than 3.5 μm. The changes in peak values of the particle number distribution (measured using the SMPS) before and after the rain events reflect the strong scavenging effect on particles within the 100-120 nm size range. The variation patterns of aerosol scattering and absorption coefficients before and after the rain events were similar, but their scavenging ratios differed, which may have been related to the aerosol particle size distribution and chemical composition.

  10. 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.

  11. Direct and Semi-direct Radiative Responses to Observation-Constrained Aerosol Absorption over S Asia

    NASA Astrophysics Data System (ADS)

    Feng, Y.; Kotamarthi, V. R.; Manoharan, V.

    2013-12-01

    Climate impacts of aerosols over S. Asia have been studied extensively in both models and observations. However, discrepancies between observed and modeled aerosol concentrations and optical properties have hindered our understanding of the aerosol influences on the regional monsoon circulation and rainfall. We present an in-depth examination of direct and semi-direct radiative responses due to aerosols on the latitudinal heating gradient and cloud distribution, with observational constraints on solar absorption by aerosols. Regional distributions of aerosol concentration are simulated with a 12-km regional climate model (WRF-Chem) driven by the NCEP analysis data from August 2011 to March 2012. During this time period, the ground-based measurements of aerosols and clouds, surface radiation, water vapor, and temperature were taken at Nainital (29.38°N, 79.45°E) during the DOE Ganges Valley Experiment (GVAX). This data set, which is available at high temporal resolution (hourly), is used to evaluate and constrain the simulated wavelength dependence of aerosol absorption and the correlation with changes in surface radiation, cloud base height and liquid water content for the entire post-monsoon period. The analysis is extended to a regional scale by comparing with satellite observation of absorbing aerosol optical depth (OMI) and cloud properties (MODIS). Preliminary results show good agreement in monthly variations of simulated and observed aerosol optical depth (AOD) except during periods of high observed AOD. Initial analysis indicates a possible local origin for the aerosols that is not captured in the model at present. Furthermore, analysis of the spectrally resolved aerosol absorption measurements indicates that these local aerosols exhibit strong absorption in near-UV and visible wavelengths. A large fraction of increased absorption during October and November (local fall harvest season) is attributable to the super-micron sized aerosol particles. In

  12. Meridional gradients in aerosol vertical distribution over Indian Mainland: Observations and model simulations

    NASA Astrophysics Data System (ADS)

    Prijith, S. S.; Suresh Babu, S.; Lakshmi, N. B.; Satheesh, S. K.; Krishna Moorthy, K.

    2016-01-01

    Multi-year observations from the network of ground-based observatories (ARFINET), established under the project 'Aerosol Radiative Forcing over India' (ARFI) of Indian Space Research Organization and space-borne lidar 'Cloud Aerosol Lidar with Orthogonal Polarization' (CALIOP) along with simulations from the chemical transport model 'Goddard Chemistry Aerosol Radiation and Transport' (GOCART), are used to characterize the vertical distribution of atmospheric aerosols over the Indian landmass and its spatial structure. While the vertical distribution of aerosol extinction showed higher values close to the surface followed by a gradual decrease at increasing altitudes, a strong meridional increase is observed in the vertical spread of aerosols across the Indian region in all seasons. It emerges that the strong thermal convections cause deepening of the atmospheric boundary layer, which although reduces the aerosol concentration at lower altitudes, enhances the concentration at higher elevations by pumping up more aerosols from below and also helping the lofted particles to reach higher levels in the atmosphere. Aerosol depolarization ratios derived from CALIPSO as well as the GOCART simulations indicate the dominance of mineral dust aerosols during spring and summer and anthropogenic aerosols in winter. During summer monsoon, though heavy rainfall associated with the Indian monsoon removes large amounts of aerosols, the prevailing southwesterly winds advect more marine aerosols over to landmass (from the adjoining oceans) leading to increase in aerosol loading at lower altitudes than in spring. During spring and summer months, aerosol loading is found to be significant, even at altitudes as high as 4 km, and this is proposed to have significant impacts on the regional climate systems such as Indian monsoon.

  13. 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.

  14. MISR Satellite Observations of Aerosol Types Affecting Human Health

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

    Ground-based observations of pollutants and concentrations of particulate matter (PM), that includes small particles designated PM2.5 and dust-dominated PM10, are the gold standard in studies of environmental impacts on human health. However, because monitoring stations are costly, they typically provide only limited spatial coverage, especially in rural and remote areas. We will demonstrate how data from the Multi-angle Imaging SpectroRadiometer (MISR) instrument that has been flying on NASA's Terra Earth Observing System satellite since early 2000 can be used to provide estimates of surface PM types. The current MISR operational aerosol retrieval uses a combination of multi-spectral and multi-angle data to retrieve aerosol optical depth (AOD) and particle property information (including dust AOD) globally at 17.6 km spatial resolution. Using the same algorithm with data collected in all 36-channels at 275 m resolution (Local Mode), which is available over greater Los Angeles area, and also was activated during 2013 DISCOVER-AQ California field campaign, high-resolution 4.4 km aerosol retrievals were performed in addition to the standard 17.6 km retrievals. The 4.4 km spatial resolution of the PM information data is fine enough to be able to resolve local differences in PM loading that may be important for understanding regional health effects of pollution in the region. In particular, we demonstrate that MISR high-resolution AOD retrievals are in better agreement with ground-based aerosol observations and reveal more details about the aerosol spatial variability compared to the MISR standard 17.6 km product. Then we will discuss techniques and show examples of the application of high-resolution MISR data to provide estimates of surface PM for the greater Los Angeles area in 2008 and for California San Joaquin Valley during the 2013 DISCOVER-AQ field campaign. Finally, we will discuss future NASA instruments that will provide new information allowing for better

  15. Low-temperature Bessel beam trap for single submicrometer aerosol particle studies

    SciTech Connect

    Lu, Jessica W.; Chasovskikh, Egor; Stapfer, David; Isenor, Merrill; Signorell, Ruth

    2014-09-01

    We report on a new instrument for single aerosol particle studies at low temperatures that combines an optical trap consisting of two counter-propagating Bessel beams (CPBBs) and temperature control down to 223 K (−50 °C). The apparatus is capable of capturing and stably trapping individual submicrometer- to micrometer-sized aerosol particles for up to several hours. First results from studies of hexadecane, dodecane, and water aerosols reveal that we can trap and freeze supercooled droplets ranging in size from ∼450 nm to 5500 nm (radius). We have conducted homogeneous and heterogeneous freezing experiments, freezing-melting cycles, and evaporation studies. To our knowledge, this is the first reported observation of the freezing process for levitated single submicrometer-sized droplets in air using optical trapping techniques. These results show that a temperature-controlled CPBB trap is an attractive new method for studying phase transitions of individual submicrometer aerosol particles.

  16. Low-temperature Bessel beam trap for single submicrometer aerosol particle studies

    NASA Astrophysics Data System (ADS)

    Lu, Jessica W.; Isenor, Merrill; Chasovskikh, Egor; Stapfer, David; Signorell, Ruth

    2014-09-01

    We report on a new instrument for single aerosol particle studies at low temperatures that combines an optical trap consisting of two counter-propagating Bessel beams (CPBBs) and temperature control down to 223 K (-50 °C). The apparatus is capable of capturing and stably trapping individual submicrometer- to micrometer-sized aerosol particles for up to several hours. First results from studies of hexadecane, dodecane, and water aerosols reveal that we can trap and freeze supercooled droplets ranging in size from ˜450 nm to 5500 nm (radius). We have conducted homogeneous and heterogeneous freezing experiments, freezing-melting cycles, and evaporation studies. To our knowledge, this is the first reported observation of the freezing process for levitated single submicrometer-sized droplets in air using optical trapping techniques. These results show that a temperature-controlled CPBB trap is an attractive new method for studying phase transitions of individual submicrometer aerosol particles.

  17. Continuous air monitor for alpha-emitting aerosol particles

    SciTech Connect

    McFarland, A.R.; Ortiz, C.A. . Dept. of Mechanical Engineering); Rodgers, J.C.; Nelson, D.C. )

    1990-01-01

    A new alpha Continuous Air Monitor (CAM) sampler is being developed for use in detecting the presence of alpha-emitting aerosol particles. The effort involves design, fabrication and evaluation of systems for the collection of aerosol and for the processing of data to speciate and quantify the alpha emitters of interest. At the present time we have a prototype of the aerosol sampling system and we have performed wind tunnel tests to characterize the performance of the device for different particle sizes, wind speeds, flow rates and internal design parameters. The results presented herein deal with the aerosol sampling aspects of the new CAM sampler. Work on the data processing, display and alarm functions is being done in parallel with the particle sampling work and will be reported separately at a later date. 17 refs., 5 figs., 3 tabs.

  18. Modeling of microphysics and optics of aerosol particles in the marine environments

    NASA Astrophysics Data System (ADS)

    Kaloshin, Gennady

    2013-05-01

    We present a microphysical model for the surface layer marine and coastal atmospheric aerosols that is based on long-term observations of size distributions for 0.01-100 μm particles. The fundamental feature of the model is a parameterization of amplitudes and widths for aerosol modes of the aerosol size distribution function (ASDF) as functions of fetch and wind speed. The shape of ASDF and its dependence on meteorological parameters, height above sea level (H), fetch (X), wind speed (U) and relative humidity (RH), are investigated. At present, the model covers the ranges H = 0 - 25 m, U = 3 - 18 km s-1, X ≤ 120 km and RH = 40 - 98%. The latest version of the Marine Aerosol Extinction Profiles model (MaexPro) is described and applied for the computation and analysis of the spectral profiles of aerosol extinction coefficients α(λ) in the wavelength band λ = 0.2-12 μm. MaexPro is based on the aforementioned aerosol model assuming spherically shaped aerosol particles and the well-known Mie theory. The spectral profiles of α(λ) calculated by MaexPro are in good agreement with observational data and the numerical results. Moreover, MaexPro was found to be an accurate and reliable tool for investigating the optical properties of atmospheric aerosols.

  19. 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.

  20. Formation of highly porous aerosol particles by atmospheric freeze-drying in ice clouds

    NASA Astrophysics Data System (ADS)

    Rudich, Yinon; Adler, Gabriela; Koop, Thomas; Taraniuk, Ilya; Moise, Tamar; Koren, Ilan; Heiblum, Reuven; Haspel, Carynelisa

    2014-05-01

    In cold high altitude cirrus clouds and anvils of high convective clouds in the tropics and mid-latitudes, ice partciles that are exposed to subsaturation conditions with respect to ice can sublimate, leaving behind residual modified aerosols. This freeze-drying process can occur in various types of clouds. In this talk we will describe experiements that simulate the atmospheric freeze-drying cycle of aerosols. We find that aerosols with high organic content can form highly porous particles (HPA) with a larger diameter and a lower density than the initial homogenous aerosol following ice subliation. We attribute this morphology change to phase separation upon freezing followed by a glass transition of the organic material that can preserve a porous structure follwoing ice sublimation. We find that the highly porous aerosol scatter solar light less efficiently than non-porous aerosol particles. A porous structure may explain the previously observed enhancement in ice nucleation efficiency of glassy organic particles. These observations may have implications for subsequent cloud formation cycles and aerosol albedo near cloud edges.

  1. 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.

  2. Raman lidar observations of particle hygroscopicity during COPS

    NASA Astrophysics Data System (ADS)

    Stelitano, D.; Di Girolamo, P.; Summa, D.

    2012-04-01

    The characterization of particle hygroscopicity has primary importance for climate monitoring and prediction. Model studies have demonstrated that relative humidity (RH) has a critical influence on aerosol climate forcing. The relationship between aerosol backscattering and relative humidity has been investigated in numerous studies (among others, Pahlow et al., 2006; Wulfmeyer and Feingold, 2000; Veselovskii et al., 2009). Hygroscopic properties of aerosols influence particle size distribution and refractive index and hence their radiative effects. Aerosol particles tend to grow at large relative humidity values as a result of their hygroscopicity. Raman lidars with aerosol, water vapour and temperature measurement capability are potentially attractive tools for studying aerosol hygroscopicity as in fact they can provide continuous altitude-resolved measurements of particle optical, size and microphysical properties, as well as relative humidity, without perturbing the aerosols or their environment. Specifically, the University of Basilicata Raman lidar system (BASIL) considered for the present study, has the capability to perform all-lidar measurements of relative humidity based on the application of both the rotational and the vibrational Raman lidar techniques in the UV. BASIL was operational in Achern (Black Forest, Lat: 48.64 ° N, Long: 8.06 ° E, Elev.: 140 m) between 25 May and 30 August 2007 in the framework of the Convective and Orographically-induced Precipitation Study (COPS). During COPS, BASIL collected more than 500 hours of measurements, distributed over 58 measurement days and 34 intensive observation periods (IOPs). The present analysis is focused on selected case studies characterized by the presence of different aerosol types with different hygroscopic behaviour. The observed behaviour, dependent upon aerosol composition, may range from hygrophobic to strongly hygroscopic. Results from the different case studies will be illustrated and

  3. 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.

  4. The Amazon tall tower observatory (ATTO) site - Multi-year aerosol observations and scientific key questions

    NASA Astrophysics Data System (ADS)

    Pöhlker, C.; Barbosa, H. M.; Brito, J.; Carbone, S.; Chi, X.; Kesselmeier, J.; Ditas, F.; Pöhlker, M. L.; Manzi, A. O.; Moran, D.; Poeschl, U.; Ruckteschler, N.; Saturno, J.; Soergel, M.; Su, H.; Walter, D.; Wang, Q.; Wang, Z.; Weber, B.; Wolff, S.; Yanez-Serrano, A. M.; Artaxo, P.; Andreae, M. O.

    2015-12-01

    The Amazon tall tower observatory site is located 150 km NE of Manaus in undisturbed rain forest areas. It serves as a remote measurement station in the Amazon forest with continuous aerosol, trace gas, micrometeorological, and ecological measurements. During part of the rainy season, the atmospheric state approximates pre-industrial conditions, in strong contrast to the dry season, which is dominated by significant pollution from deforestation fires and urban emissions. This presentation will focus on aerosol studies of the past three years. It aims to provide a brief overview of the characteristic seasonality of the aerosol burden at the ATTO site. Moreover, it will discuss the following key questions and current results of the ongoing observations: (i) During the wet season and in the absence of long-range advection of African aerosols, atmospheric conditions at the ATTO site approximate a pristine state, which reveals the genuine contribution of biogenic aerosols. Biogenic particles in the super- and submicron range have been observed and their properties as well as potential sources will be discussed. (ii) In contrast to the classical new particle formation, the occurrence of ultrafine particles is comparably sparse and mainly occurs as short 'bursts', indicating a rather localized character. Our current understanding of this phenomenon and its significance for the overall aerosol burden will be addressed. (iii) Aerosol absorptivity is mainly caused by black carbon, however, indications for the presence of other light absorbing aerosol species have been found. Current results on light absorbing aerosol under clean and polluted conditions will be presented. (iv) Aerosol particles at the ATTO site are typically strongly aged and comprise pronounced internal mixtures, with important implications for their properties. Microspectroscopic analysis helps to obtain insights into atmospheric processing and its impact on particle morphology and phase state.

  5. 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.

  6. A portable optical particle counter system for measuring dust aerosols.

    PubMed

    Marple, V A; Rubow, K L

    1978-03-01

    A portable battery-operated optical particle counter/multichannel analyzer system has been developed for the numbers size distribution and number concentration measurement of light-absorbing irregular-shaped dust particles. An inertial impactor technique has been used to obtain calibration curves by relating the magnitude of the optical counter's signal to the particle's aerodynamic or Stokes' diameter. These calibrations have been made for aerosols of coal, potash, silica, rock (copper ore), and Arizona road dust particles. PMID:645547

  7. Inside versus Outside: Ion Redistribution in Nitric Acid Reacted Sea Spray Aerosol Particles as Determined by Single Particle Analysis (Invited)

    NASA Astrophysics Data System (ADS)

    Ault, A. P.; Guasco, T.; Ryder, O. S.; Baltrusaitis, J.; Cuadra-Rodriguez, L. A.; Collins, D. B.; Ruppel, M. J.; Bertram, T. H.; Prather, K. A.; Grassian, V. H.

    2013-12-01

    Sea spray aerosol (SSA) particles were generated under real-world conditions using natural seawater and a unique ocean-atmosphere facility equipped with actual breaking waves or a marine aerosol reference tank (MART) that replicates those conditions. The SSA particles were exposed to nitric acid in situ in a flow tube and the well-known chloride displacement and nitrate formation reaction was observed. However, as discussed here, little is known about how this anion displacement reaction affects the distribution of cations and other chemical constituents within and phase state of individual SSA particles. Single particle analysis of individual SSA particles shows that cations (Na+, K+, Mg2+ and Ca2+) within individual particles undergo a spatial redistribution after heterogeneous reaction with nitric acid, along with a more concentrated layer of organic matter at the surface of the particle. These data suggest that specific ion and aerosol pH effects play an important role in aerosol particle structure in ways that have not been previously recognized. The ordering of organic coatings can impact trace gas uptake, and subsequently impact trace gas budgets of O3 and NOx.

  8. 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

  9. Aerosol Microtops II sunphotometer observations over Ukraine

    NASA Astrophysics Data System (ADS)

    Bovchaliuk, V.; Bovchaliuk, A.; Milinevsky, G.; Danylevsky, V.; Sosonkin, M.; Goloub, Ph.

    2013-08-01

    Atmospheric aerosols and their impact on climate study are based on measurements by networks of ground-based instruments, satellite sensors, and measurements on portable sunphotometers. This paper presents the preliminary aerosol characteristics obtained during 2009-2012 using portable multi-wavelength Microtops II sunphotometer. Measurements were collected at different Ukraine sites in Kyiv, Odesa, Lugansk, Rivne, Chornobyl regions. The main aerosol characteristics, namely aerosol optical thickness (AOT) and Angstroem exponent, have been retrieved and analyzed. Aerosol data processing, filtering and calibration techniques are discussed in the paper.

  10. CALIPSO Observations of Volcanic Aerosol in the Stratosphere

    NASA Technical Reports Server (NTRS)

    Thomason, Larry W.; Pitts, Michael C.

    2008-01-01

    In the stratosphere, the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) has observed the presence of aerosol plumes associated with the eruptions several volcanoes including Montserrat (May 2006), Chaiten (May 2008), and Kasatochi (August 2008). While the dense ash plumes from these eruptions dissipate relatively quickly, CALIPSO continued to detect an enhanced aerosol layer from the Montserrat eruption from the initial observations in June 2006 well into 2008. Solar occultation missions were uniquely capable of monitoring stratospheric aerosol. However, since the end of long-lived instruments like the Stratospheric Aerosol and Gas Experiment (SAGE II), there has been no clear space-based successor instrument. A number of active instruments, some employing new techniques, are being evaluated as candidate sources of stratospheric aerosol data. Herein, we examine suitability of the CALIPSO 532-nm aerosol backscatter coefficient measurements.

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

    NASA Astrophysics Data System (ADS)

    Mao, Jiandong; Li, Jinxuan

    2015-10-01

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

  12. Observational Evidence of Aerosol Enhancement of Lightning Activity and Convective Invigoration

    NASA Technical Reports Server (NTRS)

    Yuan, Tianle; Remer, Lorraine A.; Pickering, Kenneth E.; Yu, Hongbin

    2011-01-01

    Lightning activity over the West Pacific Ocean east of the Philippines is usually much less frequent than over the nearby maritime continents. However, in 2005 the Lightning Imaging Sensor (LIS) aboard the TRMM satellite observed anomalously high lightning activity in that area. In the same year the Moderate resolution Imaging Spectroradiometer (MODIS) measured anomalously high aerosol loading. The high aerosol loading was traced to volcanic activity, and not to any factor linked to meteorology, disentangling the usual convolution between aerosols and meteorology. We show that in general lightning activity is tightly correlated with aerosol loadings at both inter-annual and biweekly time scales. We estimate that a approximately 60% increase in aerosol loading leads to more than 150% increase in lightning flashes. Aerosols increase lightning activity through modification of cloud microphysics. Cloud ice particle sizes are reduced and cloud glaciation is delayed to colder temperature when aerosol loading is increased. TRMM precipitation radar measurements indicate that anomalously high aerosol loading is associated with enhanced cloud mixed phase activity and invigorated convection over the maritime ocean. These observed associations between aerosols, cloud microphysics, morphology and lightning activity are not related to meteorological variables or ENSO events. The results have important implications for understanding the variability of lightning and resulting aerosol-chemistry interactions.

  13. Modelled and observed changes in aerosols and surface solar radiation over Europe between 1960 and 2009

    NASA Astrophysics Data System (ADS)

    Turnock, S. T.; Spracklen, D. V.; Carslaw, K. S.; Mann, G. W.; Woodhouse, M. T.; Forster, P. M.; Haywood, J.; Johnson, C. E.; Dalvi, M.; Bellouin, N.; Sanchez-Lorenzo, A.

    2015-05-01

    Substantial changes in anthropogenic aerosols and precursor gas emissions have occurred over recent decades due to the implementation of air pollution control legislation and economic growth. The response of atmospheric aerosols to these changes and the impact on climate are poorly constrained, particularly in studies using detailed aerosol chemistry climate models. Here we compare the HadGEM3-UKCA coupled chemistry-climate model for the period 1960 to 2009 against extensive ground based observations of sulfate aerosol mass (1978-2009), total suspended particle matter (SPM, 1978-1998), PM10 (1997-2009), aerosol optical depth (AOD, 2000-2009) and surface solar radiation (SSR, 1960-2009) over Europe. The model underestimates observed sulfate aerosol mass (normalised mean bias factor (NMBF) = -0.4), SPM (NMBF = -0.9), PM10 (NMBF = -0.2) and aerosol optical depth (AOD, NMBF = -0.01) but slightly overpredicts SSR (NMBF = 0.02). Trends in aerosol over the observational period are well simulated by the model, with observed (simulated) changes in sulfate of -68% (-78%), SPM of -42% (-20%), PM10 of -9% (-8%) and AOD of -11% (-14%). Discrepancies in the magnitude of simulated aerosol mass do not affect the ability of the model to reproduce the observed SSR trends. The positive change in observed European SSR (5%) during 1990-2009 ("brightening") is better reproduced by the model when aerosol radiative effects (ARE) are included (3%), compared to simulations where ARE are excluded (0.2%). The simulated top-of-the-atmosphere aerosol radiative forcing over Europe under all-sky conditions increased by 3 W m-2 during the period 1970-2009 in response to changes in anthropogenic emissions and aerosol concentrations.

  14. Photoacoustics of single laser-trapped nanodroplets for the direct observation of nanofocusing in aerosol photokinetics

    NASA Astrophysics Data System (ADS)

    Cremer, Johannes W.; Thaler, Klemens M.; Haisch, Christoph; Signorell, Ruth

    2016-03-01

    Photochemistry taking place in atmospheric aerosol droplets has a significant impact on the Earth's climate. Nanofocusing of electromagnetic radiation inside aerosols plays a crucial role in their absorption behaviour, since the radiation flux inside the droplet strongly affects the activation rate of photochemically active species. However, size-dependent nanofocusing effects in the photokinetics of small aerosols have escaped direct observation due to the inability to measure absorption signatures from single droplets. Here we show that photoacoustic measurements on optically trapped single nanodroplets provide a direct, broadly applicable method to measure absorption with attolitre sensitivity. We demonstrate for a model aerosol that the photolysis is accelerated by an order of magnitude in the sub-micron to micron size range, compared with larger droplets. The versatility of our technique promises broad applicability to absorption studies of aerosol particles, such as atmospheric aerosols where quantitative photokinetic data are critical for climate predictions.

  15. Photoacoustics of single laser-trapped nanodroplets for the direct observation of nanofocusing in aerosol photokinetics.

    PubMed

    Cremer, Johannes W; Thaler, Klemens M; Haisch, Christoph; Signorell, Ruth

    2016-01-01

    Photochemistry taking place in atmospheric aerosol droplets has a significant impact on the Earth's climate. Nanofocusing of electromagnetic radiation inside aerosols plays a crucial role in their absorption behaviour, since the radiation flux inside the droplet strongly affects the activation rate of photochemically active species. However, size-dependent nanofocusing effects in the photokinetics of small aerosols have escaped direct observation due to the inability to measure absorption signatures from single droplets. Here we show that photoacoustic measurements on optically trapped single nanodroplets provide a direct, broadly applicable method to measure absorption with attolitre sensitivity. We demonstrate for a model aerosol that the photolysis is accelerated by an order of magnitude in the sub-micron to micron size range, compared with larger droplets. The versatility of our technique promises broad applicability to absorption studies of aerosol particles, such as atmospheric aerosols where quantitative photokinetic data are critical for climate predictions. PMID:26979973

  16. Satellite Observations of the Effect of Natural and Anthropogenic Aerosols on Clouds

    NASA Technical Reports Server (NTRS)

    Kaufman, Yoram J.

    2006-01-01

    Our knowledge of atmospheric aerosols (smoke, pollution, dust or sea salt particles, small enough to be suspended in the air), their evolution, composition, variability in space and time and interaction with clouds and precipitation is still lacking despite decades of research. Understanding the global aerosol system is critical to quantifying anthropogenic climate change, to determine climate sensitivity from observations and to understand the hydrological cycle. While a single instrument was used to demonstrate 50 years ago that the global CO2 levels are rising, posing threat of global warming, we need an array of satellites and field measurements coupled with chemical transport models to understand the global aerosol system. This complexity of the aerosol problem results from their short lifetime (1 week) and variable chemical composition. A new generation of satellites provides exciting opportunities to measure the global distribution of aerosols, distinguishing natural from anthropogenic aerosol and measuring their interaction with clouds and climate.

  17. Photoacoustics of single laser-trapped nanodroplets for the direct observation of nanofocusing in aerosol photokinetics

    PubMed Central

    Cremer, Johannes W.; Thaler, Klemens M.; Haisch, Christoph; Signorell, Ruth

    2016-01-01

    Photochemistry taking place in atmospheric aerosol droplets has a significant impact on the Earth's climate. Nanofocusing of electromagnetic radiation inside aerosols plays a crucial role in their absorption behaviour, since the radiation flux inside the droplet strongly affects the activation rate of photochemically active species. However, size-dependent nanofocusing effects in the photokinetics of small aerosols have escaped direct observation due to the inability to measure absorption signatures from single droplets. Here we show that photoacoustic measurements on optically trapped single nanodroplets provide a direct, broadly applicable method to measure absorption with attolitre sensitivity. We demonstrate for a model aerosol that the photolysis is accelerated by an order of magnitude in the sub-micron to micron size range, compared with larger droplets. The versatility of our technique promises broad applicability to absorption studies of aerosol particles, such as atmospheric aerosols where quantitative photokinetic data are critical for climate predictions. PMID:26979973

  18. Nabro aerosol evolution observed jointly by lidars at a mid-latitude site and CALIPSO

    NASA Astrophysics Data System (ADS)

    Zhuang, J.; Yi, F.

    2016-09-01

    Evolution of the Nabro volcanic aerosols from initially-localized plumes to a decaying hemispherically-covered layer was jointly observed by ground-based lidars at Wuhan (30.5°N, 114.4°E), China and CALIPSO. During the aerosol plume formation period, from the Nabro eruption to early July 2011, the lidar backscatter ratio related to the Nabro aerosols above Wuhan varied strongly both in vertical structure and intensity, suggesting that the Nabro aerosol distribution was horizontally inhomogeneous. The stratospheric aerosol optical depth (AOD) from CALIPSO shows that the Nabro plume first circled around the Asian monsoon anticyclone and then gradually fulfilled the whole anticyclone area with a net aerosol enhancement, which may reflect a gas-particle conversion (from sulfur dioxide gas) and/or particle injection from the upper troposphere. During the horizontal dispersion period, from early July to mid-August 2011, the stratospheric AOD over Wuhan declined rapidly since the Nabro particles were transported throughout the northern hemisphere. A nearly horizontally-uniform volcanic aerosol layer was formed. During the local cleansing period, from mid-August to the end of 2011, the Nabro aerosol layer over Wuhan had a single-peak structure and decayed uniformly. The corresponding e-folding decay time for the layer AOD is ∼130 days. The lidar measurements at Wuhan gave a small depolarization ratio and large backscatter-related Ångström exponent for the Nabro aerosols on 8 July, suggesting that the majority of these aerosols were spherical and small. The effective radius and total mass for the Nabro aerosol particles were estimated to be ∼0.26 μm and ∼0.32 Tg respectively.

  19. 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.

  20. 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...

  1. Aerosol observing system platform integration and AAF instrumentation

    SciTech Connect

    Springston, S.; Sedlacek, A.

    2010-03-15

    As part of the federal government’s 2009 American Recovery and Reinvestment Act (ARRA), the U.S. DOE Office of Science allocated funds for the capital upgrade of the Atmospheric Radiation Measurement (ARM) Climate Research Facility to improve and expand observational capabilities related to cloud and aerosol properties. The ARM Facility was established as a national user facility for the global scientific community to conduct a wide range of interdisciplinary science. Part of the ARRA-funded expansion of the ARM Facility includes four new Aerosol Observing Systems (AOS) to be designed, instrumented, and mentored by BNL. The enclosures will be customized SeaTainers. These new platforms ([AMF2]: ARM Mobile Facility-2; [TWP-D]: Tropical Western Pacific at Darwin; and [MAOS-A]/[MAOS-C]: Mobile Aerosol Observing System-Aerosol/-Chemistry) will provide a laboratory environment for fielding instruments to collect data on aerosol life cycle, microphysics, and optical/physical properties. The extensive instrument suite includes both established methods and initial deployments of new techniques to add breadth and depth to the AOS data sets. The platforms are designed: (1) to have all instruments pre-installed before deployment, allowing a higher measurement duty cycle; (2) with a standardized configuration improving the robustness of data inter-comparability; (3) to provide remote access capability for instrument mentors; and (4) to readily accommodate guest instrumentation. The first deployment of the AMF2 platform will be at the upcoming StormVEx campaign held at Steamboat Springs, Colorado, October 15, 2010–March 31, 2011 while the TWP-D AOS will be stationed at the ARM Darwin site. The maiden deployments of the MAOS-A and MAOS-C platforms will be during the Ganges Valley Experiment (GVAX) scheduled for April 2011–April 2012. In addition to the ground-based AOS platforms, thee major instrument builds for the AAF are also being undertaken (new trace gas package [NO

  2. Observation operator for the assimilation of aerosol type resolving satellite measurements into a chemical transport model

    NASA Astrophysics Data System (ADS)

    Schroedter-Homscheidt, M.; Elbern, H.; Holzer-Popp, T.

    2010-11-01

    Modelling of aerosol particles with chemical transport models is still based mainly on static emission databases while episodic emissions cannot be treated sufficiently. To overcome this situation, a coupling of chemical mass concentration modelling with satellite-based measurements relying on physical and optical principles has been developed. This study deals with the observation operator for a component-wise assimilation of satellite measurements. It treats aerosol particles classified into water soluble, water insoluble, soot, sea salt and mineral dust containing aerosol particles in the atmospheric boundary layer as separately assimilated aerosol components. It builds on a mapping of aerosol classes used both in observation and model space taking their optical and chemical properties into account. Refractive indices for primary organic carbon particles, anthropogenic particles, and secondary organic species have been defined based on a literature review. Together with a treatment of different size distributions in observations and model state, this allows transforming the background from mass concentrations into aerosol optical depths. A two-dimensional, variational assimilation is applied for component-wise aerosol optical depths. Error covariance matrices are defined based on a validation against AERONET sun photometer measurements. Analysis fields are assessed threefold: (1) through validation against AERONET especially in Saharan dust outbreak situations, (2) through comparison with the British Black Smoke and Sulphur Dioxide Network for soot-containing particles, and (3) through comparison with measurements of the water soluble components SO4, NH4, and NO3 conducted by the EMEP (European Monitoring and Evaluation Programme) network. Separately, for the water soluble, the soot and the mineral dust aerosol components a bias reduction and subsequent a root mean square error reduction is observed in the analysis for a test period from July to November 2003

  3. Observation operator for the assimilation of aerosol type resolving satellite measurements into a chemical transport model

    NASA Astrophysics Data System (ADS)

    Schroedter-Homscheidt, M.; Elbern, H.; Holzer-Popp, T.

    2010-06-01

    Modelling of aerosol particles with chemical transport models is still based mainly on static emission databases while episodic emissions can not be treated sufficiently. To overcome this situation, a coupling of chemical mass concentration modelling with satellite-based measurements relying on physical and optical principles has been developed. This study deals with the observation operator for a component-wise assimilation of satellite measurements. It treats aerosol particles classified into water soluble, water insoluble, soot, sea salt and mineral dust containing aerosol particles in the atmospheric boundary layer as separately assimilated aerosol components. It builds on a mapping of aerosol classes used both in observation and model space taking their optical and chemical properties into account. Refractive indices for primary organic carbon particles, anthropogenic particles, and secondary organic species have been defined based on a literature review. Together with a treatment of different size distributions in observations and model state, this allows transforming the background from mass concentrations into aerosol optical depths. A two-dimensional, variational assimilation is applied for component-wise aerosol optical depths. Error covariance matrices are defined based on a validation against AERONET sun photometer measurements. Analysis fields are assessed threefold: (1) through validation against AERONET especially in Saharan dust outbreak situations, (2) through comparison with the British Black Smoke and Sulphur Dioxide Network for soot-containing particles, and (3) through comparison with measurements of the water soluble components SO4, NH4, and NO3 conducted by the EMEP (European Monitoring and Evaluation Programme) network. Separately, for the water soluble, the soot and the mineral dust aerosol components a bias reduction and subsequent a root mean square error reduction is observed in the analysis for a test period from July to November 2003

  4. Characterization of Spectral Absorption Properties of Aerosols Using Satellite Observations

    NASA Technical Reports Server (NTRS)

    Torres, O.; Jethva, H.; Bhartia, P. K.; Ahn, C.

    2012-01-01

    The wavelength-dependence of aerosol absorption optical depth (AAOD) is generally represented in terms of the Angstrom Absorption Exponent (AAE), a parameter that describes the dependence of AAOD with wavelength. The AAE parameter is closely related to aerosol composition. Black carbon (BC) containing aerosols yield AAE values near unity whereas Organic carbon (OC) aerosol particles are associated with values larger than 2. Even larger AAE values have been reported for desert dust aerosol particles. Knowledge of spectral AAOD is necessary for the calculation of direct radiative forcing effect of aerosols and for inferring aerosol composition. We have developed a satellitebased method of determining the spectral AAOD of absorbing aerosols. The technique uses high spectral resolution measurements of upwelling radiation from scenes where absorbing aerosols lie above clouds as indicated by the UV Aerosol Index. For those conditions, the satellite measured reflectance (rho lambda) is approximately given by Beer's law rho lambda = rho (sub 0 lambda) e (exp -mtau (sub abs lambda)) where rho(sub 0 lambda) is the cloud reflectance, m is the geometric slant path and tau (sub abs lambda) is the spectral AAOD. The rho (sub 0 lambda) term is determined by means of radiative transfer calculations using as input the cloud optical depth derived as described in Torres et al. [JAS, 2012] that accounts for the effects of aerosol absorption. In the second step, corrections for molecular and aerosol scattering effects are applied to the cloud reflectance term, and the spectral AAOD is then derived by inverting the equation above. The proposed technique will be discussed in detail and application results will be presented. The technique can be easily applied to hyper-spectral satellite measurements that include UV such as OMI, GOME and SCIAMACHY, or to multi-spectral visible measurements by other sensors provided that the aerosol-above-cloud events are easily identified.

  5. SOIR/VEX mesospheric aerosols observations and modelling

    NASA Astrophysics Data System (ADS)

    Wilquet, Valérie; Carine Vandaele, Ann; Drummond, Rachel; Mahieux, Arnaud; Robert, Séverine; Daerden, Frank; Neary, Lori; Bertaux, Jean-Loup

    2013-04-01

    SPICAV/SOIR on-board Venus Express is able to target the layer of aerosols above the cloud layer at the terminator (Wilquet et al., 2009). A high temporal variability in the aerosol content in Venus' atmosphere was inferred from SOIR observations, as well as a latitudinal dependency of the aerosol loading (Wilquet et al., 2012). This is in agreement with results from previous missions and with the facts that (i) H2SO4 aerosol particles are formed through SO2 photo-oxidation and hydration at the cloud top of Venus, (ii) SO2 photolysis is more efficient at low latitudes, (iii) the altitude of the cloud top is up to one scale height lower in the polar region than at the equator. A increasing SO2 abundance with increasing altitude was recently observed with SPICAV-UV at altitudes of ~ 85-105 km (Belyaev et al., 2012) but also from microwave ground-based spectra in the Venus mesosphere (Sandor et al., 2010), which suggest a source of SO2 at high altitudes. Zhang et al. (2012) proposed a one dimensional photochemistry-diffusion model in order to reconcile these puzzling findings; he suggested that H2SO4 might be a source of SO2 above 90 km through aerosol evaporation followed by SO3 photolysis. This model and the observations are however disputed by others demonstrating the necessity for a more global interpretation of the observations and for modelling of the upper haze layer. For example, the variations in aerosol loading can be compared to other key parameters of the atmosphere retrieved from the same SOIR spectra such as water and SO2 composition or temperature. In addition, a microphysical model is being developed that will calculate the time dependent haze particle size distributions assuming an initial size distribution of background sulphate aerosols. The model will simulate the formation, growth, evaporation, and sedimentation of particles. Results of this on-going research will be presented and discussed. References : Belyaev, D.A., F. Montmessin, J.-L. Bertaux

  6. 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

  7. Global observations of aerosol-cloud-precipitation-climate interactions

    NASA Astrophysics Data System (ADS)

    Rosenfeld, Daniel; Andreae, Meinrat O.; Asmi, Ari; Chin, Mian; Leeuw, Gerrit; Donovan, David P.; Kahn, Ralph; Kinne, Stefan; Kivekäs, Niku; Kulmala, Markku; Lau, William; Schmidt, K. Sebastian; Suni, Tanja; Wagner, Thomas; Wild, Martin; Quaas, Johannes

    2014-12-01

    Cloud drop condensation nuclei (CCN) and ice nuclei (IN) particles determine to a large extent cloud microstructure and, consequently, cloud albedo and the dynamic response of clouds to aerosol-induced changes to precipitation. This can modify the reflected solar radiation and the thermal radiation emitted to space. Measurements of tropospheric CCN and IN over large areas have not been possible and can be only roughly approximated from satellite-sensor-based estimates of optical properties of aerosols. Our lack of ability to measure both CCN and cloud updrafts precludes disentangling the effects of meteorology from those of aerosols and represents the largest component in our uncertainty in anthropogenic climate forcing. Ways to improve the retrieval accuracy include multiangle and multipolarimetric passive measurements of the optical signal and multispectral lidar polarimetric measurements. Indirect methods include proxies of trace gases, as retrieved by hyperspectral sensors. Perhaps the most promising emerging direction is retrieving the CCN properties by simultaneously retrieving convective cloud drop number concentrations and updraft speeds, which amounts to using clouds as natural CCN chambers. These satellite observations have to be constrained by in situ observations of aerosol-cloud-precipitation-climate (ACPC) interactions, which in turn constrain a hierarchy of model simulations of ACPC. Since the essence of a general circulation model is an accurate quantification of the energy and mass fluxes in all forms between the surface, atmosphere and outer space, a route to progress is proposed here in the form of a series of box flux closure experiments in the various climate regimes. A roadmap is provided for quantifying the ACPC interactions and thereby reducing the uncertainty in anthropogenic climate forcing.

  8. Heterogeneous nucleation of ice particles on glassy aerosols modifies TTL cirrus

    NASA Astrophysics Data System (ADS)

    Wilson, T. W.; Murray, B. J.; Dobbie, S.; Al-Jumur, S. M.; Cui, Z.; Wagner, R.; Moehler, O.; Schnaiter, M.; Benz, S.; Niemand, M.; Saathoff, H.; Skrotzki, J.; Ebert, V.; Wagner, S.; Karcher, B.

    2010-12-01

    Experiments at the AIDA chamber, Karlsruhe Institute of Technology, have shown that glassy aqueous citric acid aerosol can nucleate ice at temperatures relevant to the tropical tropopause layer (TTL)(1). Modelling suggests this new route to the formation of TTL cirrus can provide an explanation for the very low ice particle number density observed in cirrus clouds in this region and may lead to high in-cloud supersaturations(1). Nucleation of ice on glassy aerosol is consistent with the absence of traditional ice nuclei in sampled TTL cirrus residue(2). In addition, we will present new data from experiments performed in July 2010 at the AIDA chamber using glassy aerosols composed of other atmospherically relevant compounds (levoglucosan, raffinose) and an internal mixture of five dicarboxylic acids and ammonium sulphate (raffinose/M5AS)(3). All four systems tested nucleate ice when in a glassy state. This indicates that heterogeneous ice nucleation is a general property of glassy aerosols and that natural aerosols which are composed of similar molecules will also nucleate ice if glassy. Glassy aqueous levoglucosan and raffinose/M5AS aerosol nucleated ice at temperatures similar to those found for glassy aqueous citric acid aerosol (<202 K). Whereas raffinose, which forms a glass at much higher temperatures, nucleated ice heterogeneously at up to ~220 K. This activity at higher temperatures suggests that ice nucleation by glassy aerosol may also play a role in the formation of warmer ice clouds. (1)B. J. Murray et al., Heterogeneous nucleation of ice particles on glassy aerosols under cirrus conditions, Nature Geosci, 2010, 3, 233-237. (2)K. D. Froyd et al., Aerosols that form subvisible cirrus at the tropical tropopause, Atmos. Chem. Phys., 2010, 10, 209-218. (3)B. Zobrist et al., Do atmospheric aerosols form glasses?, Atmos. Chem. Phys., 2008, 8, 5221-5244.

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

    SciTech Connect

    Allen, Hannah M.; Draper, Danielle C.; Ayres, Benjamin R.; Ault, Andrew P.; Bondy, Amy L.; Takahama, S.; Modini, Robert; Baumann, K.; Edgerton, Eric S.; Knote, Christoph; Laskin, Alexander; Wang, Bingbing; Fry, Juliane L.

    2015-09-25

    The 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 1 June to 15 July 2013 Southern Oxidant and Aerosol Study (SOAS) campaign. Measurements using a Monitor for AeRosols and GAses (MARGA), an ion chromatograph coupled with a wet rotating denuder and a steam-jet aerosol collector for monitoring of ambient inorganic gas and aerosol species, revealed two periods of high aerosol nitrate (NO3 ) concentrations during the campaign. These periods of high nitrate were correlated with increased concentrations of coarse mode mineral or sea spray aerosol species, particularly Na+ and Ca2+, and with a shift towards aerosol with larger (1 to 2.5 um) diameters. We suggest this nitrate aerosol forms by multiphase reactions of HNO3 and particles, reactions that are facilitated by transport of mineral 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. 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 dust 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.

  10. 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.

  11. Multiangle Imaging Spectroradiometer (MISR) Global Aerosol Optical Depth Validation Based on 2 Years of Coincident Aerosol Robotic Network (AERONET) Observations

    NASA Technical Reports Server (NTRS)

    Kahn, Ralph A.; Gaitley, Barbara J.; Martonchik, John V.; Diner, David J.; Crean, Kathleen A.; Holben, Brent

    2005-01-01

    Performance of the Multiangle Imaging Spectroradiometer (MISR) early postlaunch aerosol optical thickness (AOT) retrieval algorithm is assessed quantitatively over land and ocean by comparison with a 2-year measurement record of globally distributed AERONET Sun photometers. There are sufficient coincident observations to stratify the data set by season and expected aerosol type. In addition to reporting uncertainty envelopes, we identify trends and outliers, and investigate their likely causes, with the aim of refining algorithm performance. Overall, about 2/3 of the MISR-retrieved AOT values fall within [0.05 or 20% x AOT] of Aerosol Robotic Network (AERONET). More than a third are within [0.03 or 10% x AOT]. Correlation coefficients are highest for maritime stations (approx.0.9), and lowest for dusty sites (more than approx.0.7). Retrieved spectral slopes closely match Sun photometer values for Biomass burning and continental aerosol types. Detailed comparisons suggest that adding to the algorithm climatology more absorbing spherical particles, more realistic dust analogs, and a richer selection of multimodal aerosol mixtures would reduce the remaining discrepancies for MISR retrievals over land; in addition, refining instrument low-light-level calibration could reduce or eliminate a small but systematic offset in maritime AOT values. On the basis of cases for which current particle models are representative, a second-generation MISR aerosol retrieval algorithm incorporating these improvements could provide AOT accuracy unprecedented for a spaceborne technique.

  12. Comparison of modeled optical properties of Saharan mineral dust aerosols with SAMUM lidar and photometer observations

    NASA Astrophysics Data System (ADS)

    Gasteiger, Josef; Wiegner, Matthias

    2013-05-01

    Mineral dust aerosols are, for example, relevant for the radiative transfer in Earth's atmosphere. An important source of information on this aerosol type is provided by remote sensing using lidar systems and sun/sky photometers. We investigate the sensitivity of lidar and photometer observations to the microphysical aerosol properties in a numerical study. Knowledge of this sensitivity is required for the development of microphysical retrieval algorithms. Until recently, such retrieval algorithms were applied only to lidar or photometer observations. Quite different sensitivities for lidar and photometer are found in our study, suggesting that synergistic effects can be expected from combining the observations from both techniques. Furthermore, we compare the modeled aerosol properties to observations of Saharan mineral dust aerosols performed during the SAMUM field campaign. We determined aerosol ensembles that are consistent with the lidar as well as the photometer observations, confirming the feasibility of combining the observations from both techniques. The consistent aerosol ensembles are based on the desert mixture from the OPAC aerosol dataset, and were improved by considering mixing of absorbing and non-absorbing irregularly shaped particles.

  13. 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.

  14. Formation characteristics of aerosol particles from pulverized coal pyrolysis in high-temperature environments

    SciTech Connect

    Wei-Hsin Chen; Shan-Wen Du; Hsi-Hsien Yang; Jheng-Syun Wu

    2008-05-15

    The formation characteristics of aerosol particles from pulverized coal pyrolysis in high temperatures are studied experimentally. By conducting a drop-tube furnace, fuel pyrolysis processes in industrial furnaces are simulated in which three different reaction temperatures of 1000, 1200, and 1400{sup o}C are considered. Experimental observations indicate that when the reaction temperature is 1000{sup o}C, submicron particles are produced, whereas the particle size is dominated by nanoscale for the temperature of 1400{sup o}C. Thermogravimetric analysis of the aerosol particles stemming from the pyrolysis temperature of 1000{sup o}C reveals that the thermal behavior of the aerosol is characterized by a three-stage reaction with increasing heating temperature: (1) a volatile-reaction stage, (2) a weak-reaction stage, and (3) a soot-reaction stage. However, with the pyrolysis temperature of 1400{sup o}C, the volatile- and weak-reaction stages almost merge together and evolve into a chemical-frozen stage. The submicron particles (i.e., 1000{sup o}C) are mainly composed of volatiles, tar, and soot, with the main component of the nanoscale particles (i.e., 1400{sup o}C) being soot. The polycyclic aromatic hydrocarbons (PAHs) contained in the aerosols are also analyzed. It is found that the PAH content in generated aerosols decreases dramatically as the pyrolysis temperature increases. 31 refs., 9 figs., 1 tab.

  15. Aerosol Remote Sensing from OMI Observations: An Overview

    NASA Technical Reports Server (NTRS)

    Torres, Omar; Ahn, Changwoo; Jethva, Hiren T.

    2014-01-01

    The unique advantage of OMI observations for the characterization of aerosol properties is the availability of radiance measurement at near UV wavelengths. In spite of its coarse spatial resolution, OMI's near UV observations make possible the characterization of aerosol absorption properties. This capability is unavailable in any of the currently operational high spatial resolution aerosol sensors. A unique decadal record of aerosol absorption optical depth and single scattering albedo from near UV observations has been produced from OMI observations. In this presentation we will review the evolution of OMI's aerosol retrieval capability over the past ten years including retrieval algorithm improvements, assessment of retrieved products, and development of new retrieval capabilities to infer the optical depth of aerosol layers located above clouds.

  16. Modelling non-equilibrium secondary organic aerosol formation and evaporation with the aerosol dynamics, gas- and particle-phase chemistry kinetic multilayer model ADCHAM

    SciTech Connect

    Roldin, P.; Eriksson, A. C.; Nordin, E. Z.; Hermansson, E.; Mogensen, Ditte; Rusanen, A.; Boy, Michael; Swietlicki, E.; Svenningsson, Birgitta; Zelenyuk, Alla; Pagels, J.

    2014-08-11

    We have developed the novel Aerosol Dynamics, gas- and particle- phase chemistry model for laboratory CHAMber studies (ADCHAM). The model combines the detailed gas phase Master Chemical Mechanism version 3.2, an aerosol dynamics and particle phase chemistry module (which considers acid catalysed oligomerization, heterogeneous oxidation reactions in the particle phase and non-ideal interactions between organic compounds, water and inorganic ions) and a kinetic multilayer module for diffusion limited transport of compounds between the gas phase, particle surface and particle bulk phase. In this article we describe and use ADCHAM to study: 1) the mass transfer limited uptake of ammonia (NH3) and formation of organic salts between ammonium (NH4+) and carboxylic acids (RCOOH), 2) the slow and almost particle size independent evaporation of α-pinene secondary organic aerosol (SOA) particles, and 3) the influence of chamber wall effects on the observed SOA formation in smog chambers.

  17. 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.

  18. Chemical characterization of aerosol particles by laser Raman spectroscopy. Revision

    SciTech Connect

    Fung, K.H.

    1999-12-01

    The importance of aerosol particles in many branches of science, such as atmospheric chemistry, combustion, interfacial science, and material processing, has been steadily growing during the past decades. One of the unique properties of these particles is the very high surface-to-volume ratios, thus making them readily serve as centers for gas-phase condensation and heterogeneous reactions. These particles must be characterized by size, shape, physical state, and chemical composition. Traditionally, optical elastic scattering has been applied to obtain the physical properties of these particle (e.g., particle size, size distribution, and particle density). These physical properties are particularly important in atmospheric science as they govern the distribution and transport of atmospheric aerosols.

  19. 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

  20. On the growth of nitric and sulfuric acid aerosol particles under stratospheric conditions

    NASA Technical Reports Server (NTRS)

    Hamill, Patrick; Turco, R. P.; Toon, O. B.

    1988-01-01

    A theory for the formation of frozen aerosol particles in the Antarctic stratosphere was developed and applied to the formation of polar stratospheric clouds. The theory suggests that the condensed ice particles are composed primarily of nitric acid and water, with small admixtures of sulfuric and hydrochloric acids in solid solution. The proposed particle formation mechanism is in agreement with the magnitude and seasonal behavior of the optical extinction observed in the winter polar stratosphere.

  1. Stratospheric Aerosol--Observations, Processes, and Impact on Climate

    NASA Technical Reports Server (NTRS)

    Kresmer, Stefanie; Thomason, Larry W.; von Hobe, Marc; Hermann, Markus; Deshler, Terry; Timmreck, Claudia; Toohey, Matthew; Stenke, Andrea; Schwarz, Joshua P.; Weigel, Ralf; Fueglistaler, Stephan; Prata, Fred J.; Vernier, Jean-Paul; Schlager, Hans; Barnes, John E.; Antuna-Marrero, Juan-Carlos; Fairlie, Duncan; Palm, Mathias; Mahieu, Emmanuel; Notholt, Justus; Rex, Markus; Bingen, Christine; Vanhellemont, Filip; Bourassa, Adam; Plane, John M. C.; Klocke, Daniel; Carn, Simon A.; Clarisse, Lieven; Trickl, Thomas; Neeley, Ryan; James, Alexander D.; Rieger, Landon; Wilson, James C.; Meland, Brian

    2016-01-01

    Interest in stratospheric aerosol and its role in climate have increased over the last decade due to the observed increase in stratospheric aerosol since 2000 and the potential for changes in the sulfur cycle induced by climate change. This review provides an overview about the advances in stratospheric aerosol research since the last comprehensive assessment of stratospheric aerosol was published in 2006. A crucial development since 2006 is the substantial improvement in the agreement between in situ and space-based inferences of stratospheric aerosol properties during volcanically quiescent periods. Furthermore, new measurement systems and techniques, both in situ and space based, have been developed for measuring physical aerosol properties with greater accuracy and for characterizing aerosol composition. However, these changes induce challenges to constructing a long-term stratospheric aerosol climatology. Currently, changes in stratospheric aerosol levels less than 20% cannot be confidently quantified. The volcanic signals tend to mask any nonvolcanically driven change, making them difficult to understand. While the role of carbonyl sulfide as a substantial and relatively constant source of stratospheric sulfur has been confirmed by new observations and model simulations, large uncertainties remain with respect to the contribution from anthropogenic sulfur dioxide emissions. New evidence has been provided that stratospheric aerosol can also contain small amounts of nonsulfatematter such as black carbon and organics. Chemistry-climate models have substantially increased in quantity and sophistication. In many models the implementation of stratospheric aerosol processes is coupled to radiation and/or stratospheric chemistry modules to account for relevant feedback processes.

  2. Secondary Organic Aerosol Formation from Glyoxal: Effects of Seed Aerosol on Particle Composition

    NASA Astrophysics Data System (ADS)

    Slowik, Jay; Waxman, Eleanor; Coburn, Sean; Klein, Felix; Koenig, Theodore; Krapf, Manuel; Kumar, Nivedita; Wang, Siyuan; Baltensperger, Urs; Dommen, Josef; Prévôt, Andre; Volkamer, Rainer

    2014-05-01

    Conventional models of secondary organic aerosol (SOA) production neglect aqueous-phase processing mechanisms, thereby excluding potentially important SOA formation pathways. These missing pathways may be an important factor in the inability of current models to fully explain SOA yields and oxidation states. Molecules identified as important precursors to SOA generated through aqueous-phase include glyoxal, which is an oxidation product of numerous organic gases. Glyoxal SOA formation experiments were conducted in the PSI smog chamber as a function of seed composition, relative humidity (RH, 60 to 85%), and the presence/absence of gaseous ammonia, affecting particle acidity. In a typical experiment, the chamber was filled with the selected seed aerosol (NaCl, (NH4)2SO4, NaNO3, or K2SO4), after which glyoxal was generated by the brief (i.e. a few minutes) exposure of acetylene to UV light. The experiment was then allowed to proceed undisturbed for several hours. Each experiment consisted of several UV exposures, followed by a dilution phase at constant RH to investigate the gas/particle partitioning behavior of the generated SOA. Gas-phase glyoxal was monitored by an LED-CE-DOAS system, while the particle composition was measured using online aerosol mass spectrometry (Aerodyne HR-ToF-AMS) and offline analysis of collected filter samples. SOA composition was observed to depend strongly on seed type, with increased imidazole formation evident during experiments with (NH4)2SO¬4 and K2SO4 seeds relative to those with NaCl and NaNO3. Additionally, experiments conducted in the presence of ammonia showed large enhancements in both imidazole content and total SOA yield. Analysis of mass spectral markers indicates reversible uptake of glyoxal but irreversible particle-phase production of the imidazole-containing SOA. Positive matrix factorization (PMF) using the Multilinear Engine (ME-2) was applied to the AMS mass spectral time series to quantify factors related to

  3. Visible and near infrared observation on the Global Aerosol Backscatter Experiment (GLOBE)

    NASA Technical Reports Server (NTRS)

    Spinhirne, James D.; Cavanaugh, John F.; Chudamani, S.; Bufton, Jack L.; Sullivan, Robert J.

    1991-01-01

    The Global Aerosol Backscatter Experiment (GLOBE) was intended to provide data on prevailing values of atmospheric backscatter cross-section. The primary intent was predicting the performance of spaceborne lidar systems, most notably the Laser Atmospheric Wind Sounder (LAWS) for the Earth Observing System (EOS). The second and related goal was to understand the source and characteristics of atmospheric aerosol particles. From the GLOBE flights, extensive data was obtained on the structure of clouds and the marine planetary boundary layer. A notable result for all observations is the consistency of the large increases in the aerosol scattering ratio for the marine boundary layer. Other results are noted.

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

    DOEpatents

    Postma, A.K.

    1984-09-07

    This disclosure relates to separation of aerosol particles from gas samples withdrawn from within a contained atmosphere, such as containment vessels for nuclear reactors or other process equipment where remote gaseous sampling is required. It is specifically directed to separation of dense aerosols including particles of any size and at high mass loadings and high corrosivity. The United States Government has rights in this invention pursuant to Contract DE-AC06-76FF02170 between the US Department of Energy and Westinghouse Electric Corporation.

  5. FTIR Analysis of Functional Groups in Aerosol Particles

    NASA Astrophysics Data System (ADS)

    Shokri, S. M.; McKenzie, G.; Dransfield, T. J.

    2012-12-01

    Secondary organic aerosols (SOA) are suspensions of particulate matter composed of compounds formed from chemical reactions of organic species in the atmosphere. Atmospheric particulate matter can have impacts on climate, the environment and human health. Standardized techniques to analyze the characteristics and composition of complex secondary organic aerosols are necessary to further investigate the formation of SOA and provide a better understanding of the reaction pathways of organic species in the atmosphere. While Aerosol Mass Spectrometry (AMS) can provide detailed information about the elemental composition of a sample, it reveals little about the chemical moieties which make up the particles. This work probes aerosol particles deposited on Teflon filters using FTIR, based on the protocols of Russell, et al. (Journal of Geophysical Research - Atmospheres, 114, 2009) and the spectral fitting algorithm of Takahama, et al (submitted, 2012). To validate the necessary calibration curves for the analysis of complex samples, primary aerosols of key compounds (e.g., citric acid, ammonium sulfate, sodium benzoate) were generated, and the accumulated masses of the aerosol samples were related to their IR absorption intensity. These validated calibration curves were then used to classify and quantify functional groups in SOA samples generated in chamber studies by MIT's Kroll group. The fitting algorithm currently quantifies the following functionalities: alcohols, alkanes, alkenes, amines, aromatics, carbonyls and carboxylic acids.

  6. New particle observations in SELEX

    SciTech Connect

    Jun, Soon Yung; /Carnegie Mellon U.

    2004-12-01

    Particle observations in data from SELEX, the charm hadro-production experiment (E781) at Fermilab are reviewed. These include observations of the doubly charmed baryon {Xi}{sub cc}{sup +}(3520) and the charmed strange meson D{sub sJ}{sup +}(2632).

  7. Biogenic Potassium Salt Particles as Seeds for Secondary Organic Aerosol in the Amazon

    NASA Astrophysics Data System (ADS)

    Pöhlker, Christopher; Wiedemann, Kenia T.; Sinha, Bärbel; Shiraiwa, Manabu; Gunthe, Sachin S.; Smith, Mackenzie; Su, Hang; Artaxo, Paulo; Chen, Qi; Cheng, Yafang; Elbert, Wolfgang; Gilles, Mary K.; Kilcoyne, Arthur L. D.; Moffet, Ryan C.; Weigand, Markus; Martin, Scot T.; Pöschl, Ulrich; Andreae, Meinrat O.

    2012-08-01

    The fine particles serving as cloud condensation nuclei in pristine Amazonian rainforest air consist mostly of secondary organic aerosol. Their origin is enigmatic, however, because new particle formation in the atmosphere is not observed. Here, we show that the growth of organic aerosol particles can be initiated by potassium-salt-rich particles emitted by biota in the rainforest. These particles act as seeds for the condensation of low- or semi-volatile organic compounds from the atmospheric gas phase or multiphase oxidation of isoprene and terpenes. Our findings suggest that the primary emission of biogenic salt particles directly influences the number concentration of cloud condensation nuclei and affects the microphysics of cloud formation and precipitation over the rainforest.

  8. 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.

  9. Unique DNA-barcoded aerosol test particles for studying aerosol transport

    DOE PAGESBeta

    Harding, Ruth N.; Hara, Christine A.; Hall, Sara B.; Vitalis, Elizabeth A.; Thomas, Cynthia B.; Jones, A. Daniel; Day, James A.; Tur-Rojas, Vincent R.; Jorgensen, Trond; Herchert, Edwin; et al

    2016-03-22

    Data are presented for the first use of novel DNA-barcoded aerosol test particles that have been developed to track the fate of airborne contaminants in populated environments. Until DNATrax (DNA Tagged Reagents for Aerosol eXperiments) particles were developed, there was no way to rapidly validate air transport models with realistic particles in the respirable range of 1–10 μm in diameter. The DNATrax particles, developed at Lawrence Livermore National Laboratory (LLNL) and tested with the assistance of the Pentagon Force Protection Agency, are the first safe and effective materials for aerosol transport studies that are identified by DNA molecules. The usemore » of unique synthetic DNA barcodes overcomes the challenges of discerning the test material from pre-existing environmental or background contaminants (either naturally occurring or previously released). The DNATrax particle properties are demonstrated to have appropriate size range (approximately 1–4.5 μm in diameter) to accurately simulate bacterial spore transport. As a result, we describe details of the first field test of the DNATrax aerosol test particles in a large indoor facility.« less

  10. 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

  11. Selection of quasi-monodisperse super-micron aerosol particles

    NASA Astrophysics Data System (ADS)

    Rösch, Michael; Pfeifer, Sascha; Wiedensohler, Alfred; Stratmann, Frank

    2014-05-01

    Size-segregated quasi monodisperse particles are essential for e.g. fundamental research concerning cloud microphysical processes. Commonly a DMA (Differential Mobility Analyzer) is used to produce quasi-monodisperse submicron particles. Thereto first, polydisperse aerosol particles are bipolarly charged by a neutralizer, and then selected according to their electrical mobility with the DMA [Knutson et al. 1975]. Selecting a certain electrical mobility with a DMA results in a particle size distribution, which contains singly charged particles as well as undesired multiply charged larger particles. Often these larger particles need to either be removed from the generated aerosol or their signals have to be corrected for in the data inversion and interpretation process. This problem becomes even more serious when considering super-micron particles. Here we will present two different techniques for generating quasi-monodisperse super-micron aerosol particles with no or only an insignificant number of larger sized particles being present. First, we use a combination of a cyclone with adjustable aerodynamic cut-off diameter and our custom-built Maxi-DMA [Raddatz et al. 2013]. The cyclone removes particles larger than the desired ones prior to mobility selection with the DMA. This results in a reduction of the number of multiply charged particles of up to 99.8%. Second, we utilize a new combination of cyclone and PCVI (Pumped Counterflow Virtual Impactor), which is based on purely inertial separation and avoids particle charging. The PCVI instrument was previously described by Boulter et al. (2006) and Kulkarni et al. (2011). With our two setups we are able to produce quasi-monodisperse aerosol particles in the diameter range from 0.5 to 4.4 µm without a significant number of larger undesired particles being present. Acknowledgements: This work was done within the framework of the DFG funded Ice Nucleation research UnIT (INUIT, FOR 1525) under WE 4722/1-1. References

  12. Using OMI Observations to Measure Aerosol Absorption of Biomass Burning Aerosols Above Clouds

    NASA Technical Reports Server (NTRS)

    Torres, Omar; Bhartia, P. K.; Jethva, Hiren

    2011-01-01

    The presence of absorbing aerosol layers above clouds is unambiguously detected by the TOMS/OMI UV Aerosol Index (AI) that uses satellite observations at two near-UV channels. A sensitivity study using radiative transfer calculations shows that the AI signal of resulting from the presence of aerosols above clouds is mainly driven by the aerosol absorption optical depth and the optical depth of the underlying cloud. Based on these results, an inversion algorithm has been developed to retrieve the aerosol optical depth (AOD) of aerosol layers above clouds. In this presentation we will discuss the sensitivity analysis, describe the retrieval approach, and present results of applications of the retrieval method to OMI observations over the South Atlantic Ocean. Preliminary error analyses, to be discussed, indicate that the AOD can be underestimated (up to -30%) or overestimated (up to 60%) depending on algorithmic assumptions.

  13. New Particle Formation and Secondary Organic Aerosol in Beijing

    NASA Astrophysics Data System (ADS)

    Hu, M.; Yue, D.; Guo, S.; Hu, W.; Huang, X.; He, L.; Wiedensohler, A.; Zheng, J.; Zhang, R.

    2011-12-01

    Air pollution in Beijing has been a major concern due to being a mega-city and green Olympic Games requirements. Both long term and intensive field measurements have been conducted at an Urban Air Quality Monitoring Station in the campus of Peking University since 2004. Aerosol characteristics vary seasonally depending on meteorological conditions and source emissions. Secondary compositions of SNA (sum of sulfate, nitrate, and ammonium) and SOA (secondary organic aerosol) become major fraction of fine particles, which may enhance aerosol impacts on visibility and climate change. The transformation processes of new particle formation (NPF) and secondary organic aerosol have been focused on. It was found that gaseous sulfuric acid, ammonia, and organic compounds are important precursors to NPF events in Beijing and H2SO4-NH3-H2O ternary nucleation is one of the important mechanisms. The contributions of condensation and neutralization of sulfuric acid, coagulation, and organics to the growth of the new particles are estimated as 45%, 34%, and 21%, respectively. Tracer-based method to estimate biogenic and anthropogenic SOA was established by using gas chromatography-mass spectrometry. Secondary organic tracers derived from biogenic (isoprene, α-pinene, β-caryophyllene) and anthropogenic (toluene) contributed 32% at urban site and 35% at rural site, respectively. Other source apportionment techniques were also used to estimate secondary organic aerosols, including EC tracer method, water soluble organic carbon content, chemical mass balance model, and AMS-PMF method.

  14. Light scattering from aerosol particles in the El Paso del Norte region / the effect of humidity

    NASA Astrophysics Data System (ADS)

    Medina Calderon, Richard

    Atmospheric aerosols play an important role in climate forcing, through scattering and absorption of the incoming solar radiation. The extinction of light by the presence of atmospheric aerosols was studied using two first-principle models, and corresponding computer codes. In the first model the extinction of light from irregularly shaped aerosol particles was analyzed. In the second model it was assumed that the irregularly shaped aerosol particles were covered by a film of water, and the hygroscopicity and the extinction of light by the aerosols was analyzed. These models were then applied to the Paso del Norte region and their light extinction results compared with a local extinctiometer. The inter-comparison of the models extinction results and the extinctiometer values were well correlated. It was observed that for high humidity days the model that used an aerosol particle covered with a water film correlated better with the experimental extinctiometer measurements. While these two models were validated in the Paso del Norte region, they are also applicable to any other region, under humid or dry atmospheric conditions.

  15. Evaluation of Aerosol-Cloud Interactions in GISS ModelE Using ASR Observations

    NASA Astrophysics Data System (ADS)

    de Boer, G.; Menon, S.; Bauer, S. E.; Toto, T.; Bennartz, R.; Cribb, M.

    2011-12-01

    The impacts of aerosol particles on clouds continue to rank among the largest uncertainties in global climate simulation. In this work we assess the capability of the NASA GISS ModelE, coupled to MATRIX aerosol microphysics, in correctly representing warm-phase aerosol-cloud interactions. This evaluation is completed through the analysis of a nudged, multi-year global simulation using measurements from various US Department of Energy sponsored measurement campaigns and satellite-based observations. Campaign observations include the Aerosol Intensive Operations Period (Aerosol IOP) and Routine ARM Arial Facility Clouds with Low Optical Water Depths (CLOWD) Optical Radiative Observations (RACORO) at the Southern Great Plains site in Oklahoma, the Marine Stratus Radiation, Aerosol, and Drizzle (MASRAD) campaign at Pt. Reyes, California, and the ARM mobile facility's 2008 deployment to China. This combination of datasets provides a variety of aerosol and atmospheric conditions under which to test ModelE parameterizations. In addition to these localized comparisons, we provide the results of global evaluations completed using measurements derived from satellite remote sensors. We will provide a basic overview of simulation performance, as well as a detailed analysis of parameterizations relevant to aerosol indirect effects.

  16. Hygroscopic growth of aerosol particles in the Po Valley

    NASA Astrophysics Data System (ADS)

    Svenningsson, I. B.; Hansson, H.-C.; Wiedensohler, A.; Ogren, J. A.; Noone, K. J.; Hallberg, A.

    1992-11-01

    A Tandem Differential Mobility Analyser (TDMA) was used to study the hygroscopic growth of individual ambient aerosol particles in the Po Valley, Italy. The measurements were made during the GCE fog experiment in November 1989. During fog, the interstitial aerosol (Dp(at ambient relative humidity)<5µm) was sampled. Two modes of particles with different hygroscopic growth were found for 0.030µmparticles in the two modes were almost equal. The mean growth factor at 85% r.h. was 1.44±0.14 for the more-hygroscopic mode and 1.1±0.07 for the less-hygroscopic mode. The growth factors and the proportion of the particles that were less hygroscopic varied considerably from day to day, but no significant size dependence was seen. Comparison of growth factors for pure salt particles and the measured growth factors indicates that both hygroscopic modes contain a major insoluble part. The effect of the external mixing of hygroscopic properties on the activation of particles to fog droplets is discussed and the fraction of particles that were activated as a function of particle size is predicted. Comparison with the measured scavenging fraction as a function of particle size shows that the hygroscopic properties of the individual particle are as important as the particle size in determining if it will be activated in a fog.

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

  18. Observations of relative humidity effects on aerosol light scattering in the Yangtze River Delta of China

    NASA Astrophysics Data System (ADS)

    Zhang, L.; Sun, J. Y.; Shen, X. J.; Zhang, Y. M.; Che, H.; Ma, Q. L.; Zhang, Y. W.; Zhang, X. Y.; Ogren, J. A.

    2015-07-01

    Scattering of solar radiation by aerosol particles is highly dependent on relative humidity (RH) as hygroscopic particles take up water with increasing RH. To achieve a better understanding of the effect of aerosol hygroscopic growth on light scattering properties and radiative forcing, the aerosol scattering coefficients at RH in the range of 40 to ~ 90 % were measured using a humidified nephelometer system in the Yangtze River Delta of China in March 2013. In addition, the aerosol size distribution and chemical composition were measured. During the observation period, the mean and standard deviation (SD) of enhancement factors at RH = 85 % for the scattering coefficient (f(85 %)), backscattering coefficient (fb(85 %)), and hemispheric backscatter fraction (fβ(85 %)) were 1.58 ± 0.12, 1.25 ± 0.07, and 0.79 ± 0.04, respectively, i.e., aerosol scattering coefficient and backscattering coefficient increased by 58 and 25 % as the RH increased from 40 to 85 %. Concurrently, the aerosol hemispheric backscatter fraction decreased by 21 %. The relative amount of organic matter (OM) or inorganics in PM1 was found to be a main factor determining the magnitude of f(RH). The highest values of f(RH) corresponded to the aerosols with a small fraction of OM, and vice versa. The relative amount of NO3- in fine particles was strongly correlated with f(85 %), which suggests that NO3- played a vital role in aerosol hygroscopic growth during this study. The mass fraction of nitrate also had a close relationship to the curvature of the humidograms; higher mass fractions of nitrate were associated with humidograms that had the least curvature. Aerosol hygroscopic growth caused a 47 % increase in the calculated aerosol direct radiative forcing at 85 % RH, compared to the forcing at 40 % RH.

  19. 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

  20. Local - Air Project: Tropospheric Aerosol Monitoring by CALIPSO Lidar Satellite and Ground-Based Observations

    NASA Astrophysics Data System (ADS)

    Sarli, V.; Trippetta, S.; Bitonto, P.; Papagiannopoulos, N.; Caggiano, R.; Donvito, A.; Mona, L.

    2016-06-01

    A new method for the detection of the Planetary Boundary Layer (PBL) height from CALIPSO space-borne lidar data was developed and the possibility to infer the sub-micrometric aerosol particle (i.e., PM1) concentrations at ground level from CALIPSO observations was also explored. The comparison with ground-based lidar measurements from an EARLINET (European Aerosol Research LIdar Network) station showed the reliability of the developed method for the PBL. Moreover, empirical relationships between integrated backscatter values from CALIPSO and PM1 concentrations were found thanks to the combined use of the retrieved PBL heights, CALIPSO aerosol profiles and typing and PM1 insitu measurements.

  1. Light scattering and absorption properties of aerosol particles in the urban environment of Granada, Spain

    NASA Astrophysics Data System (ADS)

    Lyamani, H.; Olmo, F. J.; Alados-Arboledas, L.

    Surface measurements of optical and physical aerosol properties were made at an urban site, Granada (Spain) (37.18°N, 3.58°W, 680 m a.s.l), during winter 2005-2006. Measurements included the aerosol scattering, σsca, and backscattering coefficients, σbsca, at three wavelengths (450, 550 and 700 nm) measured at low relative humidity (RH<50%) by an integrating nephelometer, the absorption coefficient at 670 nm, σabs, measured with a multi-angle absorption photometer, and aerosol size distribution in the 0.5-20 μm aerodynamic diameter range registered by an aerodynamic aerosol sizer (APS-3321, TSI). The hourly average of σsca (550 nm) ranged from 2 to 424 M m -1 with an average value of 84±62 M m -1 (±S.D.). The Angstrom exponent presented an average value of 1.8±0.3, suggesting a large fraction of fine particles at the site, an observation confirmed by aerosol size distribution measurements. The hourly average of σabs (670 nm) ranged from 1.7 to 120.5 M m -1 with an average value of 28±20 M m -1. The results indicate that the aerosol absorption coefficient in Granada was relatively large. The largest σsca value was associated with air masses that passed over heavily polluted European areas and local stagnation conditions. High absorbing aerosol level was obtained during dust transport from North Africa probably due to the presence of hematite. Based on the measured scattering and absorption coefficients, a very low average value of the single scattering albedo of 0.66±0.11 at 670 nm was calculated, suggesting that urban aerosols in this region contain a large fraction of absorbing material. A clear diurnal pattern was observed in scattering and absorption coefficients and particle concentrations with two local maxima occurring in early morning and late evening. This behavior can be explained in terms of local conditions that control the particle sources associated with traffic and upward mixing of the aerosol during the daytime development of a

  2. 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

  3. Impact of aerosols and atmospheric particles on plant leaf proteins

    NASA Astrophysics Data System (ADS)

    Yan, Xing; Shi, Wen Z.; Zhao, Wen J.; Luo, Na N.

    2014-05-01

    Aerosols and atmospheric particles can diffuse and absorb solar radiation, and directly affect plant photosynthesis and related protein expression. In this study, for the first time, we performed an extensive investigation of the effects of aerosols and atmospheric particles on plant leaf proteins by combining Geographic Information System and proteomic approaches. Data on particles with diameters of 0.1-1.0 μm (PM1) from different locations across the city of Beijing and the aerosol optical depth (AOD) over the past 6 years (2007-2012) were collected. In order to make the study more reliable, we segregated the influence of soil pollution by measuring the heavy metal content. On the basis of AOD and PM1, two regions corresponding to strong and weak diffuse solar radiations were selected for analyzing the changes in the expression of plant proteins. Our results demonstrated that in areas with strong diffuse solar radiations, plant ribulose bisphosphate carboxylase was expressed at higher levels, but oxygen evolved in enhancer protein and light-harvesting complex II protein were expressed at lower levels. The expression of ATP synthase subunit beta and chlorophyll a-b binding protein were similar in both regions. By analyzing the changes in the expression of these leaf proteins and their functions, we conclude that aerosols and atmospheric particles stimulate plant photosynthesis facilitated by diffuse solar radiations.

  4. Global and Seasonal Aerosol Optical Depths Derived From Ultraviolet Observations by Satellites (TOMS)

    NASA Technical Reports Server (NTRS)

    Herman, J. R.; Torres, O.

    1999-01-01

    It has been shown that absorbing aerosols (dust, smoke, volcanic ash) can be detected in the ultraviolet wavelengths (331 nm to 380 nm) from satellite observations (TOMS, Total Ozone Mapping Spectrometer) over both land and water. The theoretical basis for these observations and their conversions to optical depths is discussed in terms of an aerosol index AI or N-value residue (assigned positive for absorbing aerosols). The theoretical considerations show that negative values of the AI frequently represent the presence of non-absorbing aerosols (NA) in the troposphere (mostly pollution in the form of sulfates, hydrocarbons, etc., and some natural sulfate aerosols) with particle sizes near 0.1 to 0.2 microns or less. The detection of small-particle non-absorbing aerosols from the measured backscattered radiances is based on the observed wavelength dependence from Mie scattering after the background Rayleigh scattering is subtracted. The Mie scattering from larger particles, 1 micron or more (e.g., cloud water droplets) has too small a wavelength dependence to be detected by this method. In regions that are mostly cloud free, aerosols of all sizes can be seen in the single channel 380 nm or 360 nm radiance data. The most prominent Al feature observed is the strong asymmetry in aerosol amount between the Northern and Southern Hemispheres, with the large majority of NA occurring above 20degN latitude. The maximum values of non-absorbing aerosols are observed over the eastern U.S. and most of western Europe corresponding to the areas of highest industrial pollution. Annual cycles in the amount of NA are observed over Europe and North America with maxima occurring in the summer corresponding to times of minimum wind transport. Similarly, the maxima in the winter over the Atlantic Ocean occurs because of wind borne transport from the land. Most regions of the world have the maximum amount of non-absorbing aerosol in the December to January period except for the eastern

  5. Rocket-borne probes for charged mesospheric aerosol particles

    NASA Astrophysics Data System (ADS)

    Robertson, S.; Horanyi, M.; Sternovsky, Z.

    We describe a series of rocket-borne probes for detecting charged solid particles in the ionosphere. The first type of probe is a flat charge-collecting surface on the skin of the rocket. Behind this surface is a permanent magnet that shields the probe from electrons. The current that is recorded is thus from heavier charged aerosol particles. This heavy charge carrier current is converted to a charge number density. A probe launched from White Sands in November 1998 detected a narrow layer at 86 km consistent with sporadic E layer of metallic ions. Two launches were made from the Andoya Rocket Range (Norway) during the MIDAS SOLSTICE campaign in the summer of 2001. Layers of positively and negatively charged aerosol particles were detected on both flights, but inadvertent positive ion collection complicated the analysis. Subsequent payloads included a second probe that supplemented the magnetic field with a positive bias voltage to improve positive ion rejection. Three launches were made from Andoya during the MIDAS MacWAVE campaign in July 2003 with this dual-probe package. Within PMSE, the probes measured an aerosol particle distribution, clearly resolving small positive, small negative, and large negative particles. A new mass-analyzing probe is being developed in which electric fields within the nosecone deflect charged aerosol particles admitted at the nosecone tip. This probe takes advantage of the reduced density behind the shock front to increase the mean free path within the instrument so that cryopumping is not required. The new probe has three pairs of collection surfaces with opposite polarities for collecting (1) electrons and light ions, (2) particles with mass 150-103 amu, and (3) particles with mass 103 -- 2 x 104 amu.

  6. Fog Induced Aerosol Modification Observed by AERONET, Including Occurrences During Major Air Pollution Events

    NASA Astrophysics Data System (ADS)

    Eck, T. F.; Holben, B. N.; Reid, J. S.; Giles, D. M.; Rivas, M.; Singh, R. P.; Tripathi, S. N.; Bruegge, C. J.; Li, Z.; Platnick, S. E.; Arnold, T.; Ferrare, R. A.; Hostetler, C. A.; Burton, S. P.; Kim, J.; Kim, Y. J.; Sinyuk, A.; Dubovik, O.; Arola, A. T.; Schafer, J.; Artaxo, P.; Smirnov, A.; Chen, H.; Goloub, P.

    2014-12-01

    The modification of aerosol optical properties due to interaction with fog is examined from measurements made by sun/sky radiometers at several AERONET sites. Retrieved total column volume size distributions for cases identified as aerosol modified by fog often show very a large 'middle mode' submicron radius (~0.4 to 0.5 microns), which is typically seen as a component of a bimodal sub-micron distribution. These middle mode sized particles are often called cloud-processed or residual aerosol. This bimodal accumulation mode distribution may be due to one mode (the larger one) from fog-processed aerosol and the other from interstitial aerosol, or possibly from two different aerosol species (differing chemical composition) with differing hygroscopic growth factors. The size of the fine mode particles from AERONET retrieved for these cases exceeds the size of sub-micron sized particles retrieved for nearly all other aerosol types, suggesting significant modification of aerosols within the fog or cloud environment. In-situ measured aerosol size distributions made during other fog events are compared to the AERONET retrievals, and show close agreement in the residual mode particle size. Almucantar retrievals are analyzed from the Kanpur site in the Indo-Gangetic Plain in India (fog in January), Beijing (fog in winter), Fresno, CA in the San Joaquin Valley (fog in winter), South Korea (Yellow Sea fog in spring), Arica on the northern coast of Chile (stratocumulus), and several other sites with aerosol observations made after fog dissipated. Additionally, several major air pollution events are discussed where extremely high aerosol concentrations were measured at the surface and during which fog also occurred, resulting in the detection very large fine mode aerosols (residual mode) from AERONET retrievals in some of these events. Low wind speeds that occurred during these events were conducive to both pollutant accumulation and also fog formation. The presence of fog then

  7. Fog Induced Aerosol Modification Observed by AERONET, Including Occurrences During Major Air Pollution Events

    NASA Astrophysics Data System (ADS)

    Eck, T. F.; Holben, B. N.; Reid, J. S.; Giles, D. M.; Rivas, M.; Singh, R. P.; Tripathi, S. N.; Bruegge, C. J.; Li, Z.; Platnick, S. E.; Arnold, T.; Ferrare, R. A.; Hostetler, C. A.; Burton, S. P.; Kim, J.; Kim, Y. J.; Sinyuk, A.; Dubovik, O.; Arola, A. T.; Schafer, J.; Artaxo, P.; Smirnov, A.; Chen, H.; Goloub, P.

    2015-12-01

    The modification of aerosol optical properties due to interaction with fog is examined from measurements made by sun/sky radiometers at several AERONET sites. Retrieved total column volume size distributions for cases identified as aerosol modified by fog often show very a large 'middle mode' submicron radius (~0.4 to 0.5 microns), which is typically seen as a component of a bimodal sub-micron distribution. These middle mode sized particles are often called cloud-processed or residual aerosol. This bimodal accumulation mode distribution may be due to one mode (the larger one) from fog-processed aerosol and the other from interstitial aerosol, or possibly from two different aerosol species (differing chemical composition) with differing hygroscopic growth factors. The size of the fine mode particles from AERONET retrieved for these cases exceeds the size of sub-micron sized particles retrieved for nearly all other aerosol types, suggesting significant modification of aerosols within the fog or cloud environment. In-situ measured aerosol size distributions made during other fog events are compared to the AERONET retrievals, and show close agreement in the residual mode particle size. Almucantar retrievals are analyzed from the Kanpur site in the Indo-Gangetic Plain in India (fog in January), Beijing (fog in winter), Fresno, CA in the San Joaquin Valley (fog in winter), South Korea (Yellow Sea fog in spring), Arica on the northern coast of Chile (stratocumulus), and several other sites with aerosol observations made after fog dissipated. Additionally, several major air pollution events are discussed where extremely high aerosol concentrations were measured at the surface and during which fog also occurred, resulting in the detection very large fine mode aerosols (residual mode) from AERONET retrievals in some of these events. Low wind speeds that occurred during these events were conducive to both pollutant accumulation and also fog formation. The presence of fog then

  8. 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

  9. 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.

  10. Thermal desorption single particle mass spectrometry of ambient aerosol in Shanghai

    NASA Astrophysics Data System (ADS)

    Zhai, Jinghao; Wang, Xinning; Li, Jingyan; Xu, Tingting; Chen, Hong; Yang, Xin; Chen, Jianmin

    2015-12-01

    Submicron aerosol volatility, chemical composition, and mixing state were simultaneously measured using a thermodenuder (TD) in-line with a single particle aerosol mass spectrometry (SPAMS) during Nov.12 to Dec. 11 of 2014 in Shanghai. By heating up to 250 °C, the signals of refractory species such as elemental carbon, metallic compounds, and mineral dust in aerosols were enhanced in the mass spectra. At 250 °C, the main particle types present in the size range of 0.2-1.0 μm were biomass burning (37% by number) and elemental carbon (20%). From 1.0 to 2.0 μm, biomass burning (30%), dust (19%) and metal-rich (18%) were the primary particle types. CN- signal remained in the mass spectra of the heated biomass burning particles suggests the existence of some extremely low-volatility nitrogen-containing organics. Laboratory experiments were conducted by burning rice straws, the main source material of biomass burning particles in Southern China, to confirm the less volatile composition contributed by biomass burning. Strong CN- with relative area >0.21 was observed in most of the laboratory-made biomass burning particles when heated above 200 °C and was selected as a new marker to identify the biomass burning particles in the field. The TD-SPAMS measured the size-resolved chemical composition of the individual particle residues at different temperatures and offered more information on the aging processes of primary particles and their sources.

  11. Single particle multichannel bio-aerosol fluorescence sensor.

    PubMed

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

    2005-05-16

    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 ~1mum 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. PMID:19495264

  12. 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.

  13. Observational Study and Parameterization of Aerosol-fog Interactions

    NASA Astrophysics Data System (ADS)

    Duan, J.; Guo, X.; Liu, Y.; Fang, C.; Su, Z.; Chen, Y.

    2014-12-01

    Studies have shown that human activities such as increased aerosols affect fog occurrence and properties significantly, and accurate numerical fog forecasting depends on, to a large extent, parameterization of fog microphysics and aerosol-fog interactions. Furthermore, fogs can be considered as clouds near the ground, and enjoy an advantage of permitting comprehensive long-term in-situ measurements that clouds do not. Knowledge learned from studying aerosol-fog interactions will provide useful insights into aerosol-cloud interactions. To serve the twofold objectives of understanding and improving parameterizations of aerosol-fog interactions and aerosol-cloud interactions, this study examines the data collected from fogs, with a focus but not limited to the data collected in Beijing, China. Data examined include aerosol particle size distributions measured by a Passive Cavity Aerosol Spectrometer Probe (PCASP-100X), fog droplet size distributions measured by a Fog Monitor (FM-120), Cloud Condensation Nuclei (CCN), liquid water path measured by radiometers and visibility sensors, along with meteorological variables measured by a Tethered Balloon Sounding System (XLS-Ⅱ) and Automatic Weather Station (AWS). The results will be compared with low-level clouds for similarities and differences between fogs and clouds.

  14. Mass analysis of charged aerosol particles in NLC and PMSE during the ECOMA/MASS campaign

    NASA Astrophysics Data System (ADS)

    Robertson, S.; Horányi, M.; Knappmiller, S.; Sternovsky, Z.; Holzworth, R.; Shimogawa, M.; Friedrich, M.; Torkar, K.; Gumbel, J.; Megner, L.; Baumgarten, G.; Latteck, R.; Rapp, M.; Hoppe, U.-P.; Hervig, M. E.

    2009-03-01

    MASS (Mesospheric Aerosol Sampling Spectrometer) is a multichannel mass spectrometer for charged aerosol particles, which was flown from the Andøya Rocket Range, Norway, through NLC and PMSE on 3 August 2007 and through PMSE on 6 August 2007. The eight-channel analyzers provided for the first time simultaneous measurements of the charge density residing on aerosol particles in four mass ranges, corresponding to ice particles with radii <0.5 nm (including ions), 0.5-1 nm, 1-2 nm, and >3 nm (approximately). Positive and negative particles were recorded on separate channels. Faraday rotation measurements provided electron density and a means of checking charge density measurements made by the spectrometer. Additional complementary measurements were made by rocket-borne dust impact detectors, electric field booms, a photometer and ground-based radar and lidar. The MASS data from the first flight showed negative charge number densities of 1500-3000 cm-3 for particles with radii >3 nm from 83-88 km approximately coincident with PMSE observed by the ALWIN radar and NLC observed by the ALOMAR lidar. For particles in the 1-2 nm range, number densities of positive and negative charge were similar in magnitude (~2000 cm-3) and for smaller particles, 0.5-1 nm in radius, positive charge was dominant. The occurrence of positive charge on the aerosol particles of the smallest size and predominately negative charge on the particles of largest size suggests that nucleation occurs on positive condensation nuclei and is followed by collection of negative charge during subsequent growth to larger size. Faraday rotation measurements show a bite-out in electron density that increases the time for positive aerosol particles to be neutralized and charged negatively. The larger particles (>3 nm) are observed throughout the NLC region, 83-88 km, and the smaller particles are observed primarily at the high end of the range, 86-88 km. The second flight into PMSE alone at 84-88 km, found only

  15. 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

  16. Dispersion of aerosol particles in the atmosphere: Fukushima

    NASA Astrophysics Data System (ADS)

    Haszpra, Tímea; Lagzi, István; Tél, Tamás

    2013-04-01

    Investigation of dispersion and deposition of aerosol particles in the atmosphere is an essential issue, because they have an effect on the biosphere and atmosphere. Moreover, aerosol particles have different transport properties and chemical and physical transformations in the atmosphere compared to gas phase air pollutants. The motion of a particle is described by a set of ordinary differential equations. The large-scale dynamics in the horizontal direction can be described by the equations of passive scalar advection, but in the vertical direction a well-defined terminal velocity should be taken into account as a term added to the vertical wind component. In the planetary boundary layer turbulent diffusion has an important role in the particle dispersion, which is taken into account by adding stochastic terms to the deterministic equations above. Wet deposition is also an essential process in the lower levels of the atmosphere, however, its precise parameterization is a challenge. For the simulations the wind field and other necessary data were taken from the ECMWF ERA-Interim database. In the case of the Fukushima Daiichi nuclear disaster (March-April 2011) radioactive aerosol particles were also released in the planetary boundary layer. Simulations (included the continuous and varying emission from the nuclear power plant) will be presented for the period of 14-23 March. Results show that wet deposition also has to be taken into consideration in the lower levels of the atmosphere. Furthermore, dynamical system characteristics are evaluated for the aerosol particle dynamics. The escape rate of particles was estimated both with and without turbulent diffusion, and in both cases when there was no wet deposition and also when wet deposition was taken into consideration.

  17. Design of Aerosol Particle Coating: Thickness, Texture and Efficiency

    PubMed Central

    Buesser, B.; Pratsinis, S.E.

    2013-01-01

    Core-shell particles preserve the performance (e.g. magnetic, plasmonic or opacifying) of a core material while modifying its surface with a shell that facilitates (e.g. by blocking its reactivity) their incorporation into a host liquid or polymer matrix. Here coating of titania (core) aerosol particles with thin silica shells (films or layers) is investigated at non-isothermal conditions by a trimodal aerosol dynamics model, accounting for SiO2 generation by gas phase and surface oxidation of hexamethyldisiloxane (HMDSO) vapor, coagulation and sintering. After TiO2 particles have reached their final primary particle size (e.g. upon completion of sintering during their flame synthesis), coating starts by uniformly mixing them with HMDSO vapor that is oxidized either in the gas phase or on the particles’ surface resulting in SiO2 aerosols or deposits, respectively. Sintering of SiO2 deposited onto the core TiO2 particles takes place transforming rough into smooth coating shells depending on process conditions. The core-shell characteristics (thickness, texture and efficiency) are calculated for two limiting cases of coating shells: perfectly smooth (e.g. hermetic) and fractal-like. At constant TiO2 core particle production rate, the influence of coating weight fraction, surface oxidation and core particle size on coating shell characteristics is investigated and compared to pertinent experimental data through coating diagrams. With an optimal temperature profile for complete precursor conversion, the TiO2 aerosol and SiO2-precursor (HMDSO) vapor concentrations have the strongest influence on product coating shell characteristics. PMID:23729833

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

    NASA Astrophysics Data System (ADS)

    Leiterer, U.; Sakunov, G.

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

  19. Vertical profiles of atmospheric fluorescent aerosols observed by a mutil-channel lidar spectrometer system

    NASA Astrophysics Data System (ADS)

    Huang, Z.; Huang, J.; Zhou, T.; Sugimoto, N.; Bi, J.

    2015-12-01

    Zhongwei Huang1*, Jianping Huang1, Tian Zhou1, Nobuo Sugimoto2, Jianrong Bi1 and Jinsen Shi11Key Laboratory for Semi-Arid Climate Change of the Ministry of Education, College of Atmospheric Sciences, Lanzhou University, Lanzhou, China. 2Atmospheric Environment Division, National Institutes for Environmental Studies, Tsukuba, Japan Email: huangzhongwei@lzu.edu.cn Abstract Atmospheric aerosols have a significant impact on regional and globe climate. The challenge in quantifying aerosol direct radiative forcing and aerosol-cloud interactions arises from large spatial and temporal heterogeneity of aerosol concentrations, compositions, sizes, shape and optical properties (IPCC, 2007). Lidar offers some remarkable advantages for determining the vertical structure of atmospheric aerosols and their related optical properties. To investigate the characterization of atmospheric aerosols (especially bioaerosols) with high spatial and temporal resolution, we developed a Raman/fluorescence/polarization lidar system employed a multi-channel spectrometer, with capabilities of providing measurements of Raman scattering and laser-induced fluorescence excitation at 355 nm from atmospheric aerosols. Meanwhile, the lidar system operated polarization measurements both at 355nm and 532nm wavelengths, aiming to obtain more information of aerosols. It employs a high power pulsed laser and a received telescope with 350mm diameter. The receiver could simultaneously detect a wide fluorescent spectrum about 178 nm with spectral resolution 5.7 nm, mainly including an F/3.7 Crossed Czerny-Turner spectrograph, a grating (1200 gr/mm) and a PMT array with 32 photocathode elements. Vertical structure of fluorescent aerosols in the atmosphere was observed by the developed lidar system at four sites across northwest China, during 2014 spring field observation that conducted by Lanzhou University. It has been proved that the developed lidar could detect the fluorescent aerosols with high temporal and

  20. Ambient particle characterization by single particle aerosol mass spectrometry in an urban area of Beijing

    NASA Astrophysics Data System (ADS)

    Li, Lei; Li, Mei; Huang, Zhengxu; Gao, Wei; Nian, Huiqing; Fu, Zhong; Gao, Jian; Chai, Fahe; Zhou, Zhen

    2014-09-01

    To investigate the composition and possible sources of aerosol particles in Beijing urban area, a single particle aerosol mass spectrometer (SPAMS) was deployed from April 22 to May 4, 2011. 510,341 particles out of 2,953,200 sized particles were characterized by SPAMS in combination with the ART-2a neural network algorithm. The particles were classified as rich-K (39.79%), carbonaceous species (32.7%), industry metal (19.2%), dust (5.7%), and rich-Na (1.76%). Industrial emissions related particles, rich-Fe, rich-Pb, and K-nitrate, were the major components of aerosol particles during haze periods, which were mainly from the steel plants and metal smelting processes around Beijing. Under stagnant meterological conditions, these regional emissions have a vital effect on haze formation. Organic carbon (OC) particles were attributed to biomass burning. NaK-EC was likely to come from local traffic emissions. Internally mixed organic and elemental carbon (OCEC) was found to be from possible sources of local traffic emission and biomass burning. It was found that coarse dust particles were mainly composed of four different types of dust particles, dust-Si, dust-Ca, dust-Al, and dust-Ti. It is the first time that SPAMS was used to study a dust storm in Beijing. Our results showed that SPAMS could be a powerful tool in the identification and apportionment of aerosol sources in Beijing, providing useful reference information for environmental control and management.

  1. PREDICTED AND OBSERVED BEHAVIOR OF PLATELET AEROSOLS

    EPA Science Inventory

    A theory describing the aerodynamic behavior of triaxial particles was recently presented. he formulation of particle motion was developed by regressing numerically predicted aerodynamic diameters on particle axial dimensions used in numerical simulations, and provided an excelle...

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

    PubMed

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

    2016-09-01

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

  3. Aerosol particles and the formation of advection fog

    NASA Technical Reports Server (NTRS)

    Hung, R. J.; Liaw, G. S.; Vaughan, O. H., Jr.

    1979-01-01

    A study of numerical simulation of the effects of concentration, particle size, mass of nuclei, and chemical composition on the dynamics of warm fog formation, particularly the formation of advection fog, is presented. This formation is associated with the aerosol particle characteristics, and both macrophysical and microphysical processes are considered. In the macrophysical model, the evolution of wind components, water vapor content, liquid water content, and potential temperature under the influences of vertical turbulent diffusion, turbulent momentum, and turbulent energy transfers are taken into account. In the microphysical model, the supersaturation effect is incorporated with the surface tension and hygroscopic material solution. It is shown that the aerosol particles with the higher number density, larger size nuclei, the heavier nuclei mass, and the higher ratio of the Van't Hoff factor to the molecular weight favor the formation of the lower visibility advection fogs with stronger vertical energy transfer during the nucleation and condensation time period.

  4. Towards an integrated optical single aerosol particle lab.

    PubMed

    Horstmann, Marcel; Probst, Karl; Fallnich, Carsten

    2012-01-21

    We present a manipulation and characterization system for single airborne particles which is integrated onto a microscope slide. Trapped particles are manipulated by means of radiation pressure and characterized by cavity enhanced Raman spectroscopy. Optical fibers are used to deliver the trapping laser light as well as to collect the Raman scattered light, allowing for a flexible usage of the device. The system features a sample chamber which is separated from an aerosol-flooded injection chamber by means of a light guiding glass-capillary. The coupling of this device with an aerosol optical tweezers setup to selectively load its trapping sites is demonstrated. Finally, a route towards chip-integrated handling and processing of multiple particles is shown and the first results are presented. PMID:22105700

  5. 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.

  6. 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

  7. Bromide content of sea-salt aerosol particles collected over the Indian Ocean during INDOEX 1999

    NASA Astrophysics Data System (ADS)

    Gabriel, R.; von Glasow, R.; Sander, R.; Andreae, M. O.; Crutzen, P. J.

    2002-10-01

    Bromide can be depleted from sea-salt aerosol particles in the marine boundary layer (MBL) and converted to reactive gas-phase species like Br, BrO, and HOBr, which affect ozone chemistry. Air pollution can enhance the bromine release from sea-salt aerosols and thus inject additional bromine into the MBL. During the winter monsoon the northern Indian Ocean is strongly affected by air pollution from the Indian subcontinent and Asia. As part of the Indian Ocean Experiment (INDOEX), aerosol particles were sampled with stacked filter units (SFU) on the NCAR Hercules C-130 aircraft during February-March 1999. We determined the vertical and latitudinal distribution of the major inorganic aerosol components (NH4+, Na+, K+, Mg2+, Ca2+, Cl-, NO3-, SO42-) and the Br- content of the coarse aerosol to examine the role of the bromine release on the gas-phase chemistry in the marine boundary layer over the tropical Indian Ocean. The aerosol mass and composition varied significantly with air mass origin and sampling location. In the northern part of the Indian Ocean (5°-15°N, 66°-73°E), high concentrations of pollution-derived inorganic species were found in the marine boundary layer extending from the sea surface to about 1.2 km above sea level. In this layer, the average mass concentration of all aerosol species detected by our technique was comparable to pollution levels observed in industrialized regions. In the Southern Hemisphere (1°-9°S, 66°- 73°E), the aerosol concentrations rapidly declined to remote background levels. A chloride loss from the coarse aerosol particles was observed in parallel to the latitudinal gradient of the non sea salt SO42- burden. In most of the samples, Br- was depleted from the sea-salt aerosols. However, we found an enrichment in bromide in aerosols affected by air masses originating over strong pollution sources in India (Bombay, Calcutta). In these cases the additional pollution-derived Br from organo-halogen additives in petrol

  8. 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

  9. 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

  10. Remote Sensing of Aerosol Over the Land from the Earth Observing System MODIS Instrument

    NASA Technical Reports Server (NTRS)

    Kaufman, Yoram; Tanre, Didier; Remer, Lorraine; Einaudi, Franco (Technical Monitor)

    2000-01-01

    On Dec 18, 1999, NASA launched the Moderate-Resolution Imaging Spectroradiometer (MODIS) instrument on the Earth Observing System (EOS) Terra mission, in a spectacular launch. The mission will provide morning (10:30 AM) global observations of aerosol and other related parameters. It will be followed a year later by a MODIS instrument on EOS Aqua for afternoon observations (1:30 PM). MODIS will measure aerosol over land and ocean with its eight 500 m and 250 m channels in the solar spectrum (0-41 to 2.2 micrometers). Over the land MODIS will measure the total column aerosol loading, and distinguish between submicron pollution particles and large soil particles. Standard daily products of resolution of ten kilometers and global mapped eight day and monthly products on a 1x1 degree global scale will be produced routinely and make available for no or small reproduction charge to the international community. Though the aerosol products will not be available everywhere over the land, it is expected that they will be useful for assessments of the presence, sources and transport of urban pollution, biomass burning aerosol, and desert dust. Other measurements from MODIS will supplement the aerosol information, e.g., land use change, urbanization, presence and magnitude of biomass burning fires, and effect of aerosol on cloud microphysics. Other instruments on Terra, e.g. Multi-angle Imaging SpectroRadiometer (MISR) and the Clouds and the Earth's Radiant Energy System (CERES), will also measure aerosol, its properties and radiative forcing in tandem with the MODIS measurements. During the Aqua period, there are plans to launch in 2003 the Pathfinder Instruments for Cloud and Aerosol Spaceborne Observations (PICASSO) mission for global measurements of the aerosol vertical structure, and the PARASOL mission for aerosol characterization. Aqua-MODIS, PICASSO and PARASOL will fly in formation for detailed simultaneous characterization of the aerosol three-dimensional field, which

  11. The lofting of Western Pacific regional aerosol by island thermodynamics as observed around Borneo

    NASA Astrophysics Data System (ADS)

    Robinson, N. H.; Allan, J. D.; Trembath, J. A.; Rosenberg, P. D.; Allen, G.; Coe, H.

    2012-07-01

    Vertical profiles of aerosol chemical composition, number concentration and size were measured throughout the lower troposphere of Borneo, a large tropical island in the western Pacific Ocean. Aerosol composition, size and number concentration measurements (using an Aerodyne Aerosol Mass Spectrometer, Passive Cavity Aerosol Spectrometer Probe and Condensation Particle Counter, respectively) were made both upwind and downwind of Borneo, as well as over the island itself, on board the UK BAe-146 research aircraft as part of the OP3 project. Two meteorological regimes were identified - one dominated by isolated terrestrial convection (ITC) which peaked in the afternoon, and the other characterised by more regionally active mesoscale convective systems (MCS). Upwind profiles show aerosol to be confined to a shallow marine boundary layer below 930 ± 10 hPa (~760 m above sea level, a.s.l.). As this air mass advects over the island with the mean free troposphere synoptic flow during the ITC-dominated regime, it is convectively lofted above the terrestrial surface mixed layer to heights of between 945 ± 22 (~630 m a.s.l.) and 740 ± 44 hPa (~2740 m a.s.l.), consistent with a coupling between the synoptic steering level flow and island sea breeze circulations. Terrestrial aerosol was observed to be lofted into this higher layer through both moist convective uplift and transport through turbulent diurnal sea-breeze cells. At the peak of convective activity in the mid-afternoons, organic aerosol loadings in the lofted layer were observed to be substantially higher than in the morning (by a mean factor of three). This organic matter is dominated by secondary aerosol from processing of biogenic gas phase precursors. Aerosol number concentration profiles suggest formation of new particles aloft in the atmosphere. By the time the air mass reaches the west coast of the island, terrestrial aerosol is enhanced in the lofted layer. Such uplift of aerosol in Borneo is expected to

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

    PubMed

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

    2016-08-01

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

  13. Ruby lidar observations and trajectory analysis of stratospheric aerosols injected by the volcanic eruptions of El Chichon

    NASA Technical Reports Server (NTRS)

    Uchino, O.; Tabata, T.; Akita, I.; Okada, Y.; Naito, K.

    1985-01-01

    Large amounts of aerosol particles and gases were injected into the lower stratosphere by the violet volcanic eruptions of El Chichon on March 28, and April 3 and 4, 1982. Observational results obtained by a ruby lidar at Tsukuba (36.1 deg N, 140.1 deg E) are shown, and some points of latitude dispersion processes of aerosols are discussed.

  14. The influence of meteoric smoke particles on stratospheric aerosol properties

    NASA Astrophysics Data System (ADS)

    Mann, Graham; Brooke, James; Dhomse, Sandip; Plane, John; Feng, Wuhu; Neely, Ryan; Bardeen, Chuck; Bellouin, Nicolas; Dalvi, Mohit; Johnson, Colin; Abraham, Luke

    2016-04-01

    The ablation of metors in the thermosphere and mesosphere introduces a signficant source of particulate matter into the polar upper stratosphere. These meteoric smoke particles (MSP) initially form at nanometre sizes but in the stratosphere have grown to larger sizes (tens of nanometres) following coagulation. The presence of these smoke particles may represent a significant mechanism for the nucleation of polar stratospheric clouds and are also known to influence the properties of the stratospheric aerosol or Junge layer. In this presentation we present findings from experiments to investigate the influence of the MSP on the Junge layer, carried out with the UM-UKCA composition-climate model. The UM-UKCA model is a high-top (up to 80km) version of the general circulation model with well-resolved stratospheric dynamics, includes the aerosol microphysics module GLOMAP and has interactive sulphur chemistry suitable for the stratosphere and troposphere (Dhomse et al., 2014). We have recently added to UM-UKCA a source of meteoric smoke particles, based on prescribing the variation of the smoke particles from previous simulations with the Whole Atmosphere Community Climate Model (WACCM). In UM-UKCA, the MSP particles are transported within the GLOMAP aerosol framework, alongside interactive stratospheric sulphuric acid aerosol. For the experiments presented here, we have activated the interaction between the MSP and the stratospheric sulphuric acid aerosol. The MSP provide an important sink term for the gas phase sulphuric acid simulated in the model, with subsequent effects on the formation, growth and temporal evolution of stratospheric sulphuric acid aerosol particles. By comparing simulations with and without the MSP-sulphur interactions we quantify the influence of the meteoric smoke on the properties of volcanically-quiescent Junge layer. We also investigate the extent to which the MSP may modulate the effects from SO2 injected into the stratosphere from volcanic

  15. 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

  16. Quantification of aerosol chemical composition using continuous single particle measurements

    NASA Astrophysics Data System (ADS)

    Jeong, C.-H.; McGuire, M. L.; Godri, K. J.; Slowik, J. G.; Rehbein, P. J. G.; Evans, G. J.

    2011-07-01

    Mass concentrations of sulphate, nitrate, ammonium, organic carbon (OC), elemental carbon (EC) were determined from real time single particle data in the size range 0.1-3.0 μm measured by an Aerosol Time-of-Flight Mass Spectrometer (ATOFMS) at urban and rural sites in Canada. To quantify chemical species within individual particles measured by an ATOFMS, ion peak intensity of m/z -97 for sulphate, -62 for nitrate, +18 for ammonium, +43 for OC, and +36 for EC were scaled using the number and size distribution data by an Aerodynamic Particle Sizer (APS) and a Fast Mobility Particle Sizer (FMPS). Hourly quantified chemical species from ATOFMS single-particle analysis were compared with collocated fine particulate matter (aerodynamic diameter < 2.5 μm, PM2.5) chemical composition measurements by an Aerosol Mass Spectrometer (AMS) at a rural site, a Gas-Particle Ion Chromatograph (GPIC) at an urban site, and a Sunset Lab field OCEC analyzer at both sites. The highest correlation was found for nitrate, with correlation coefficients (Pearson r) of 0.89 (ATOFMS vs. GPIC) and 0.85 (ATOFMS vs. AMS). ATOFMS mass calibration factors, determined for the urban site, were used to calculate mass concentrations of the major PM2.5 chemical components at the rural site near the US border in southern Ontario. Mass reconstruction using the ATOFMS mass calibration factors agreed very well with the PM2.5 mass concentrations measured by a Tapered Element Oscillating Microbalance (TEOM, r = 0.86) at the urban site and a light scattering monitor (DustTrak, r = 0.87) at the rural site. In the urban area nitrate was the largest contributor to PM2.5 mass in the winter, while organics and sulphate contributed ~64 % of the summer PM2.5 in the rural area, suggesting a strong influence of regional/trans-boundary pollution. The mass concentrations of five major species in ten size-resolved particle-types and aerosol acidity of each particle-type were determined for the rural site. On a mass basis

  17. Ultrasensitive detection of inhaled organic aerosol particles by accelerator mass spectrometry.

    PubMed

    Parkhomchuk, E V; Gulevich, D G; Taratayko, A I; Baklanov, A M; Selivanova, A V; Trubitsyna, T A; Voronova, I V; Kalinkin, P N; Okunev, A G; Rastigeev, S A; Reznikov, V A; Semeykina, V S; Sashkina, K A; Parkhomchuk, V V

    2016-09-01

    Accelerator mass spectrometry (AMS) was shown to be applicable for studying the penetration of organic aerosols, inhaled by laboratory mice at ultra-low concentration ca. 10(3) cm(-3). We synthesized polystyrene (PS) beads, composed of radiocarbon-labeled styrene, for testing them as model organic aerosols. As a source of radiocarbon we used methyl alcohol with radioactivity. Radiolabeled polystyrene beads were obtained by emulsifier-free emulsion polymerization of synthesized (14)C-styrene initiated by K2S2O8 in aqueous media. Aerosol particles were produced by pneumatic spraying of diluted (14)C-PS latex. Mice inhaled (14)C-PS aerosol consisting of the mix of 10(3) 225-nm particles per 1 cm(3) and 5·10(3) 25-nm particles per 1 cm(3) for 30 min every day during five days. Several millions of 225-nm particles deposited in the lungs and slowly excreted from them during two weeks of postexposure. Penetration of particles matter was also observed for liver, kidneys and brain, but not for a heart. PMID:27281540

  18. The regime of biomass burning aerosols over the Mediterranean basin based on satellite observations

    NASA Astrophysics Data System (ADS)

    Kalaitzi, Nikoleta; Gkikas, Antonis; Papadimas, Christos. D.; Hatzianastassiou, Nikolaos; Torres, Omar; Mihalopoulos, Nikolaos

    2016-04-01

    Biomass burning (BB) aerosol particles have significant effects on global and regional climate, as well as on regional air quality, visibility, cloud processes and human health.Biomass burning contributes by about 40% to the global emission of black carbonBC, and BB aerosols can exert a significant positive radiative forcing. The BB aerosols can originate from natural fires and human induced burning, such as wood or agricultural waste. However, the magnitude, but also the sign of the radiative forcing of BB aerosols is still uncertain, according to the third assessment report of IPCC (2013). Moreover, there are significant differences between different models as to their representation (inventories) of BB aerosols, more than for others, e.g. of fossil fuel origin. Therefore, it is important to better understand the spatial and temporal regime of BB aerosols. This is attempted here for the broader Mediterranean basin, which is a very interesting study area for aerosols, also being one of the most climaticallysensitive world regions. The determination of spatial and temporal regime of Mediterranean BB aerosols premises the identification of these particles at a complete spatial and long temporal coverage. Such a complete coverage is only ensured by contemporary satellite observations, which offer a challenging ability to characterize the existence of BB aerosols. This is possible thanks to the current availability of derived satellite products offering information on the size and absorption/scattering ability of aerosol particles. A synergistic use of such satellite aerosol data is made here, in conjunction with a developed algorithm, in order to identify the existence of BB aerosols over the Mediterranean basin over the 11-year period from 2005 to 2015. The algorithm operates, on a daily basis and at 1°×1°latitude-longitude resolution, setting threshold values (criteria) for specific physical and optical properties, which are representative of BB aerosols. More

  19. Chemometric analysis of multi-sensor hyperspectral images of coarse mode aerosol particles for the image-based investigation on aerosol particles

    NASA Astrophysics Data System (ADS)

    Ofner, Johannes; Kamilli, Katharina A.; Eitenberger, Elisabeth; Friedbacher, Gernot; Lendl, Bernhard; Held, Andreas; Lohninger, Hans

    2015-04-01

    Multi-sensor hyperspectral imaging is a novel technique, which allows the determination of composition, chemical structure and pure components of laterally resolved samples by chemometric analysis of different hyperspectral datasets. These hyperspectral datasets are obtained by different imaging methods, analysing the same sample spot and superimposing the hyperspectral data to create a single multi-sensor dataset. Within this study, scanning electron microscopy (SEM), Raman and energy-dispersive X-ray spectroscopy (EDX) images were obtained from size-segregated aerosol particles, sampled above Western Australian salt lakes. The particles were collected on aluminum foils inside a 2350 L Teflon chamber using a Sioutas impactor, sampling aerosol particles of sizes between 250 nm and 10 µm. The complex composition of the coarse-mode particles can be linked to primary emissions of inorganic species as well as to oxidized volatile organic carbon (VOC) emissions. The oxidation products of VOC emissions are supposed to form an ultra-fine nucleation mode, which was observed during several field campaigns between 2006 and 2013. The aluminum foils were analysed using chemical imaging and electron microscopy. A Horiba LabRam 800HR Raman microscope was used for vibrational mapping of an area of about 100 µm x 100 µm of the foils at a resolution of about 1 µm. The same area was analysed using a Quanta FEI 200 electron microscope (about 250 nm resolution). In addition to the high-resolution image, the elemental composition could be investigated using energy-dispersive X-ray spectroscopy. The obtained hyperspectral images were combined into a multi-sensor dataset using the software package Imagelab (Epina Software Labs, www.imagelab.at). After pre-processing of the images, the multi-sensor hyperspectral dataset was analysed using several chemometric methods such as principal component analysis (PCA), hierarchical cluster analysis (HCA) and other multivariate methods. Vertex

  20. Polarization properties of aerosol particles over western Japan: classification, seasonal variation, and implications for air quality

    NASA Astrophysics Data System (ADS)

    Pan, Xiaole; Uno, Itsushi; Hara, Yukari; Osada, Kazuo; Yamamoto, Shigekazu; Wang, Zhe; Sugimoto, Nobuo; Kobayashi, Hiroshi; Wang, Zifa

    2016-08-01

    Ground-based observation of the polarization properties of aerosol particles using a polarization optical particle counter (POPC) was made from 27 October 2013, to 31 December 2015, at a suburban site in the Kyushu area of Japan. We found that the depolarization ratio (DR, the fraction of s-polarized signal in the total backward light scattering signal) of aerosol particles showed prominent seasonal variability, with peaks in spring (0.21-0.23) and winter (0.19-0.23), and a minimum value (0.09-0.14) in summer. The aerosol compositions in both fine mode (aerodynamic diameter of particle, Dp < 2.5 µm) and coarse mode (2.5 µm < Dp < 10 µm), and the size-dependent polarization characteristics were analyzed for long-range transport dust particles, sea salt, and anthropogenic pollution-dominant aerosols. The DR value increased with increasing particle size, and DR = 0.1 was a reliable threshold value to identify the sphericity of supermicron (Dp > 1 µm) particles. Occurrence of substandard air quality days in Kyushu was closely related with mixed type (coexistence of anthropogenic pollutants and dust particles in the atmosphere), especially in winter and spring, indicating that dust events in the Asian continent played a key role in the cross-boundary transport of continental pollution. Backward trajectory analysis demonstrated that air masses originating from the western Pacific contained large amounts of spherical particles due to the influence of sea salt, especially in summer; however, for air masses from the Asian continent, the dependence of number fraction of spherical particles on air relative humidity was insignificant, indicating the predominance of less-hygroscopic substances (e.g., mineral dust), although the mass concentrations of anthropogenic pollutants were elevated.

  1. Characterization of the Aerosol Instrument Package for the In-service Aircraft Global Observing System IAGOS

    NASA Astrophysics Data System (ADS)

    Bundke, Ulrich; Berg, Marcel; Tettig, Frank; Franke, Harald; Petzold, Andreas

    2015-04-01

    The atmospheric aerosol influences the climate twofold via the direct interaction with solar radiation and indirectly effecting microphysical properties of clouds. The latter has the largest uncertainty according to the last IPPC Report. A measured in situ climatology of the aerosol microphysical properties is needed to reduce the reported uncertainty of the aerosol climate impact. The European Research Infrastructure IAGOS (In-service Aircraft for a Global Observing System; www.iagos.org) responds to the increasing requests for long-term, routine in situ observational data by using commercial passenger aircraft as measurement platform. However, scientific instrumentation for the measurement of atmospheric constituents requires major modifications before being deployable aboard in-service passenger aircraft. The IAGOS Aerosol Package (IAGOS-P2C) consists of two modified Butanol based CPCs (Model Grimm 5.410) and one optical particle counter (Model Grimm Sky OPC 1.129). A thermodenuder at 250°C is placed upstream the second CPC, thus the number concentrations of the total aerosol and the non-volatile aerosol fraction is measured. The Sky OPC measures the size distribution in the rage theoretically up to 32 μ m. Because of the inlet cut off diameter of D50=3 μ m we are using the 16 channel mode in the range of 250 nm - 2.5 μ m at 1 Hz resolution. In this presentation the IAGOS Aerosol package is characterized for pressure levels relevant for the planned application, down to cruising level of 150 hPa including the inlet system. In our aerosol lab we have tested the system against standard instrumentation with different aerosol test substances in a long duration test. Particle losses are characterized for the inlet system. In addition first results for airborne measurements are shown from a first field campaign.

  2. Airborne Observations of Regional Variations in Fluorescent Aerosol Across the U.S.

    NASA Astrophysics Data System (ADS)

    Perring, A. E.; Schwarz, J. P.; Baumgardner, D.; Hernandez, M.; Spracklen, D. V.; Heald, C. L.; Gao, R. S.; Kok, G. L.; McMeeking, G.; McQuaid, J. B.; Fahey, D. W.

    2014-12-01

    Airborne observations of fluorescent aerosol were made aboard an airship during CloudLab, a series of flights that took place in September and October of 2013 and covered a wide band of longitude across the continental US between Florida and California between 28 and 37N latitude. Sampling occurred from near the surface to 1000 m above the ground. A Wide-band Integrated Bioaerosol Sensor (WIBS-4) measured concentrations of supermicron fluorescent particles with average regional concentrations ranging from 1.4±0.7 to 6.8±1.4 x 104 particles m-3 and representing up to 24% of total supermicron particle number. We observed distinct variations in size distributions and fluorescent characteristics in different regions, and attribute these to geographically diverse bioaerosol populations. Fluorescent aerosol signatures detected in the east is largely consistent with those of mold spores observed in a laboratory setting. A shift to larger sizes associated with different fluorescent patterns is observed in the west. Loadings in the desert west were nearly as high as those near the Gulf of Mexico, indicating that bioaerosol is a substantial component of supermicron aerosol both of these humid and arid environments. The observations are compared to simulated fungal and bacterial loadings. Good agreement in both particle size and concentrations is observed in the east. In the west the model underestimates observed concentrations by a factor of 2 to 3 and the prescribed particle sizes are smaller than the observed bioaerosol.

  3. PARTICLE SIZE DISTRIBUTIONS FOR AN OFFICE AEROSOL

    EPA Science Inventory

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

  4. Aerosol observations and growth rates downwind of the anvil of a deep tropical thunderstorm

    NASA Astrophysics Data System (ADS)

    Waddicor, D. A.; Vaughan, G.; Choularton, T. W.; Bower, K. N.; Coe, H.; Gallagher, M.; Williams, P. I.; Flynn, M.; Volz-Thomas, A.; Pätz, H.-W.; Isaac, P.; Hacker, J.; Arnold, F.; Schlager, H.; Whiteway, J. A.

    2012-07-01

    We present a case study of Aitken and accumulation mode aerosol observed downwind of the anvil of a deep tropical thunderstorm. The measurements were made by condensation nuclei counters flown on the Egrett high-altitude aircraft from Darwin during the ACTIVE campaign, in monsoon conditions producing widespread convection over land and ocean. Maximum measured concentrations of aerosol with diameter greater than 10 nm were 25 000 cm-3 (STP). By calculating back-trajectories from the observations, and projecting onto infrared satellite images, the time since the air exited cloud was estimated. In this way a time scale of about 3 hours was derived for the Aitken aerosol concentration to reach its peak. We examine the hypothesis that the growth in aerosol concentrations can be explained by production of sulphuric acid from SO2 followed by particle nucleation and coagulation. Estimates of the sulphuric acid production rate show that the observations are only consistent with this hypothesis if the particles coagulate to sizes >10 nm much more quickly than is suggested by current theory. Alternatively, other condensible gases (possibly organic) drive the growth of aerosol particles in the TTL.

  5. Characterization of intense aerosol episodes in the Mediterranean basin from satellite observations

    NASA Astrophysics Data System (ADS)

    Gkikas, Antonis; Hatzianastassiou, Nikos; Mihalopoulos, Nikolaos

    2014-05-01

    The properties and distribution of aerosols over the broader Mediterranean region are complex since particles of different nature are either produced within its boundaries or transported from other regions. Thus, coarse dust aerosols are transported primarily from Sahara and secondarily from Middle East, while fine polluted aerosols are either produced locally from anthropogenic activities or they are transported from neighbouring or remote European areas. Also during summer biomass aerosols are transported towards the Mediterranean, originating from massive and extended fires occurring in northern Balkans and Eastern Europe and favoured by the prevailing synoptic conditions. In addition, sea-salt aerosols originate from the Mediterranean Sea or the Atlantic Ocean. Occasionally, aerosols are encountered at very high concentrations (aerosol episodes or events) significantly affecting atmospheric dynamics and climate as well as human health. Given the coexistence of different aerosols as internal and external mixtures characterizing and discriminating between the different types of aerosol episodes is a big challenge. A characterization and classification of intense aerosol episodes in the Mediterranean basin (March 2000 - February 2007) is attempted in the present study. This is achieved by implementing an objective and dynamic algorithm which uses daily aerosol optical properties derived from satellite measurements, namely MODIS-Terra, Earth Probe (EP)-TOMS and OMI-Aura. The aerosol episodes are first classified into strong and extreme ones, according to their intensity, by means of aerosol optical depth at 550nm (AOD550nm). Subsequently, they are discriminated into the following aerosol types: (i) biomass/urban-industrial (BU), (ii) desert dust (DD), (iii) sea-salt like (SS), (iv) mixed (MX) and (v) undetermined (UN). The classification is based on aerosol optical properties accounting for the particles' size (Ångström exponent, Effective radius), the

  6. Quantitative determination of carbonaceous particle mixing state in Paris using single particle mass spectrometer and aerosol mass spectrometer measurements

    NASA Astrophysics Data System (ADS)

    Healy, R. M.; Sciare, J.; Poulain, L.; Crippa, M.; Wiedensohler, A.; Prévôt, A. S. H.; Baltensperger, U.; Sarda-Estève, R.; McGuire, M. L.; Jeong, C.-H.; McGillicuddy, E.; O'Connor, I. P.; Sodeau, J. R.; Evans, G. J.; Wenger, J. C.

    2013-04-01

    Single particle mixing state information can be a powerful tool for assessing the relative impact of local and regional sources of ambient particulate matter in urban environments. However, quantitative mixing state data are challenging to obtain using single particle mass spectrometers. In this study, the quantitative chemical composition of carbonaceous single particles has been estimated using an aerosol time-of-flight mass spectrometer (ATOFMS) as part of the MEGAPOLI 2010 winter campaign in Paris, France. Relative peak areas of marker ions for elemental carbon (EC), organic aerosol (OA), ammonium, nitrate, sulphate and potassium were compared with concurrent measurements from an Aerodyne high resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS), a thermal/optical OCEC analyser and a particle into liquid sampler coupled with ion chromatography (PILS-IC). ATOFMS-derived mass concentrations reproduced the variability of these species well (R2 = 0.67-0.78), and ten discrete mixing states for carbonaceous particles were identified and quantified. Potassium content was used to identify particles associated with biomass combustion. The chemical mixing state of HR-ToF-AMS organic aerosol factors, resolved using positive matrix factorization, was also investigated through comparison with the ATOFMS dataset. The results indicate that hydrocarbon-like OA (HOA) detected in Paris is associated with two EC-rich mixing states which differ in their relative sulphate content, while fresh biomass burning OA (BBOA) is associated with two mixing states which differ significantly in their OA/EC ratios. Aged biomass burning OA (OOA2-BBOA) was found to be significantly internally mixed with nitrate, while secondary, oxidized OA (OOA) was associated with five particle mixing states, each exhibiting different relative secondary inorganic ion content. Externally mixed secondary organic aerosol was not observed. These findings demonstrate the heterogeneity of primary and

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

    NASA Technical Reports Server (NTRS)

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

    2003-01-01

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

  8. Aerosol optical depth retrieval using the MERIS observation

    NASA Astrophysics Data System (ADS)

    Mei, Linlu; Rozanov, Vladimir; Vountas, Marco; Burrows, John P.

    2015-04-01

    Surface reflectance determination and aerosol type selection are the two main challenges for space-borne aerosol remote sensing, especially for those instruments lacking of near-infrared channels, high-temporal observations, multi-angles abilities and/or polarization information. However, space based instruments like the MEdium Resolution Imaging Spectrometer (MERIS) and the successor, Ocean and Land Colour Instrument (OLCI) with high calibration accuracy and high spatial resolution provide unique abilities for obtaining valuable aerosol information for a better understanding of the impact of aerosols on climate, which is still one of the largest uncertainties of global climate change evaluation. In this study, a new Aerosol Optical Depth (AOD) retrieval algorithm is presented. Global aerosol type and surface spectral dataset were used for the aerosol type selection and surface reflectance determination. A modified Ross-Li mode is used to describe the surface Bidirectional Reflectance Distribution Function (BRDF) effect. The comparison with operational MODIS C6 product and the validation using AErosol RObotic NETwork (AERONET) show promising results.

  9. Aerosols in Amazonia: Natural biogenic particles and large scale biomass burning impacts

    NASA Astrophysics Data System (ADS)

    Artaxo, Paulo; Barbosa, Henrique M. J.; Rizzo, Luciana V.; Brito, Joel F.; Sena, Elisa T.; Cirino, Glauber G.; Arana, Andrea

    2013-05-01

    The Large Scale Biosphere Atmosphere Experiment in Amazonia (LBA) is a long term (20 years) research effort aimed at the understanding of the functioning of the Amazonian ecosystem. In particular, the strong biosphere-atmosphere interaction is a key component looking at the exchange processes between vegetation and the atmosphere, focusing on aerosol particles. Two aerosol components are the most visible: The natural biogenic emissions of aerosols and VOCs, and the biomass burning emissions. A large effort was done to characterize natural biogenic aerosols that showed detailed organic characterization and optical properties. The biomass burning component in Amazonia is important in term of aerosol and trace gases emissions, with deforestation rates decreasing, from 27,000 Km2 in 2004 to about 5,000 Km2 in 2011. Biomass burning emissions in Amazonia increases concentrations of aerosol particles, CO, ozone and other species, and also change the surface radiation balance in a significant way. Long term monitoring of aerosols and trace gases were performed in two sites: a background site in Central Amazonia, 55 Km North of Manaus (called ZF2 ecological reservation) and a monitoring station in Porto Velho, Rondonia state, a site heavily impacted by biomass burning smoke. Several instruments were operated to measured aerosol size distribution, optical properties (absorption and scattering at several wavelengths), composition of organic (OC/EC) and inorganic components among other measurements. AERONET and MODIS measurements from 5 long term sites show a large year-to year variability due to climatic and socio-economic issues. Aerosol optical depths of more than 4 at 550nm was observed frequently over biomass burning areas. In the pristine Amazonian atmosphere, aerosol scattering coefficients ranged between 1 and 200 Mm-1 at 450 nm, while absorption ranged between 1 and 20 Mm-1 at 637 nm. A strong seasonal behavior was observed, with greater aerosol loadings during the

  10. The single scattering properties of the aerosol particles as aggregated spheres

    NASA Astrophysics Data System (ADS)

    Wu, Y.; Gu, X.; Cheng, T.; Xie, D.; Yu, T.; Chen, H.; Guo, J.

    2012-08-01

    The light scattering and absorption properties of anthropogenic aerosol particles such as soot aggregates are complicated in the temporal and spatial distribution, which introduce uncertainty of radiative forcing on global climate change. In order to study the single scattering properties of anthorpogenic aerosol particles, the structures of these aerosols such as soot paticles and soot-containing mixtures with the sulfate or organic matter, are simulated using the parallel diffusion limited aggregation algorithm (DLA) based on the transmission electron microscope images (TEM). Then, the single scattering properties of randomly oriented aerosols, such as scattering matrix, single scattering albedo (SSA), and asymmetry parameter (AP), are computed using the superposition T-matrix method. The comparisons of the single scattering properties of these specific types of clusters with different morphological and chemical factors such as fractal parameters, aspect ratio, monomer radius, mixture mode and refractive index, indicate that these different impact factors can respectively generate the significant influences on the single scattering properties of these aerosols. The results show that aspect ratio of circumscribed shape has relatively small effect on single scattering properties, for both differences of SSA and AP are less than 0.1. However, mixture modes of soot clusters with larger sulfate particles have remarkably important effects on the scattering and absorption properties of aggregated spheres, and SSA of those soot-containing mixtures are increased in proportion to the ratio of larger weakly absorbing attachments. Therefore, these complex aerosols come from man made pollution cannot be neglected in the aerosol retrievals. The study of the single scattering properties on these kinds of aggregated spheres is important and helpful in remote sensing observations and atmospheric radiation balance computations.

  11. 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

  12. Optical scattering patterns from single urban aerosol particles at Adelphi, Maryland, USA: A classification relating to particle morphologies

    NASA Astrophysics Data System (ADS)

    Aptowicz, K. B.; Pinnick, R. G.; Hill, S. C.; Pan, Y. L.; Chang, R. K.

    2006-06-01

    Angularly resolved elastic light scattering patterns from individual atmospheric aerosol particles (diameter 0.5-12 micrometers) sampled during fall (October 2004) at an urban site in the Baltimore-Washington metroplex are reported. These two-dimensional angular optical scattering (TAOS) patterns were collected for polar scattering angles θ varying from approximately 75° to 135° and azimuthal angles ϕ varying from 0° to 360°. Approximately 6000 scattering patterns were sampled over a span of 18 hours from an inlet located above our laboratory roof at Adelphi, Maryland. Our instrument recorded light scattering patterns of higher resolution and accuracy than have previously been achievable. The patterns suggest that background aerosol particles have diverse morphologies ranging from single spheres to complex structures. The frequency of occurrence of particle morphologies inferred from the TAOS patterns is strongly dependent on size. For nominally 1-μm particles, 65% appear spherical (or perturbed sphere) and only about 9% have complex structure (as suggested by their complex scattering features); whereas for nominally 5-μm particles, only 5% appear spherical (or perturbed sphere) and 71% appear to have complex structure. The patterns are quantitatively characterized using a degree of symmetry (Dsym) factor, calculated by examining both mirror and rotational symmetries in each pattern. In our measurements, atmospheric particles have two distinct populations: mostly micron-sized particles with Dsym values close to that of spheres and a population of mostly supermicron particles having a low but broad range of Dsym values. These observations are consistent with the commonly accepted notion that most micron-sized particles (in the accumulation mode) appear to be nearly spherical and are probably formed in the atmosphere through gas-particle reactions; whereas most supermicron particles appear to be nonspherical and are likely directly injected into the

  13. Fluorescence lifetime imaging of optically levitated aerosol: a technique to quantitatively map the viscosity of suspended aerosol particles.

    PubMed

    Fitzgerald, C; Hosny, N A; Tong, H; Seville, P C; Gallimore, P J; Davidson, N M; Athanasiadis, A; Botchway, S W; Ward, A D; Kalberer, M; Kuimova, M K; Pope, F D

    2016-08-21

    We describe a technique to measure the viscosity of stably levitated single micron-sized aerosol particles. Particle levitation allows the aerosol phase to be probed in the absence of potentially artefact-causing surfaces. To achieve this feat, we combined two laser based techniques: optical trapping for aerosol particle levitation, using a counter-propagating laser beam configuration, and fluorescent lifetime imaging microscopy (FLIM) of molecular rotors for the measurement of viscosity within the particle. Unlike other techniques used to measure aerosol particle viscosity, this allows for the non-destructive probing of viscosity of aerosol particles without interference from surfaces. The well-described viscosity of sucrose aerosol, under a range of relative humidity conditions, is used to validate the technique. Furthermore we investigate a pharmaceutically-relevant mixture of sodium chloride and salbutamol sulphate under humidities representative of in vivo drug inhalation. Finally, we provide a methodology for incorporating molecular rotors into already levitated particles, thereby making the FLIM/optical trapping technique applicable to real world aerosol systems, such as atmospheric aerosols and those generated by pharmaceutical inhalers. PMID:27430158

  14. Detection of cw-related species in complex aerosol particles deposited on surfaces with an ion trap-based aerosol mass spectrometer

    SciTech Connect

    Harris, William A; Reilly, Pete; Whitten, William B

    2007-01-01

    A new type of aerosol mass spectrometer was developed by minimal modification of an existing commercial ion trap to analyze the semivolatile components of aerosols in real time. An aerodynamic lens-based inlet system created a well-collimated particle beam that impacted into the heated ionization volume of the commercial ion trap mass spectrometer. The semivolatile components of the aerosols were thermally vaporized and ionized by electron impact or chemical ionization in the source. The nascent ions were extracted and injected into the ion trap for mass analysis. The utility of this instrument was demonstrated by identifying semivolatile analytes in complex aerosols. This study is part of an ongoing effort to develop methods for identifying chemical species related to CW agent exposure. Our efforts focused on detection of CW-related species doped on omnipresent aerosols such as house dust particles vacuumed from various surfaces found in any office building. The doped aerosols were sampled directly into the inlet of our mass spectrometer from the vacuumed particle stream. The semivolatile analytes were deposited on house dust and identified by positive ion chemical ionization mass spectrometry up to 2.5 h after deposition. Our results suggest that the observed semivolatile species may have been chemisorbed on some of the particle surfaces in submonolayer concentrations and may remain hours after deposition. This research suggests that identification of trace CW agent-related species should be feasible by this technique.

  15. Code System to Calculate Particle Penetration Through Aerosol Transport Lines.

    1999-07-14

    Version 00 Distribution is restricted to US Government Agencies and Their Contractors Only. DEPOSITION1.03 is an interactive software program which was developed for the design and analysis of aerosol transport lines. Models are presented for calculating aerosol particle penetration through straight tubes of arbitrary orientation, inlets, and elbows. An expression to calculate effective depositional velocities of particles on tube walls is derived. The concept of maximum penetration is introduced, which is the maximum possible penetrationmore » through a sampling line connecting any two points in a three-dimensional space. A procedure to predict optimum tube diameter for an existing transport line is developed. Note that there is a discrepancy in this package which includes the DEPOSITION 1.03 executable and the DEPOSITION 2.0 report. RSICC was unable to obtain other executables or reports.« less

  16. Production, Organic Characterization, and Phase Transformations of Marine Particles Aerosolized from a Laboratory Mesocosm Phytoplankton Bioreactor

    NASA Astrophysics Data System (ADS)

    Alpert, P. A.; Knopf, D. A.; Aller, J. Y.; Radway, J.; Kilthau, W.

    2012-12-01

    artificial seawater show agreement with previous studies. As the phytoplankton population grows, particle production increases, with particles smaller than 200 nm in diameter primarily contributing to this increase. CCSEM/EDAX and STXM/NEXAFS analysis shows that phytoplankton presence can result in purely organic airborne particles, NaCl particles coated with organic material and organic particles containing phytoplankton frustule fragments. We also have observed that submicrometer particles can efficiently nucleate ice and that the same ice nucleating particles examined with CCSEM/EDAX and STXM/NEXAFS contain significant organic material by mass. These results will aid in understanding the effects of biological activity on the composition and mixing state of ocean derived aerosol particles and their potential impact on cold cloud formation.

  17. 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

  18. Characteristics of aerosols in urban and rural areas: GEOS-Chem+APM nested grid simulation and comparison with observations

    NASA Astrophysics Data System (ADS)

    Luo, G.; Yu, F.

    2011-12-01

    Aerosol microphysics (nucleation, condensation, growth and coagulation) shows significant impact on aerosol size distribution which is important for the investigation of aerosol properties and its associated environment and climate impacts. Here, we use a recently developed global size-resolved aerosol microphysics model (GEOS-Chem+APM, Yu and Luo, ACP, 2009), which uses the ion-mediated nucleation theory to simulate tropospheric particle formation and a new scheme to consider the kinetic condensation of low volatile secondary organic gas (SOG) (in addition to H2SO4 gas) on nucleated particles, to study the major characteristics of aerosol size distribution in urban and rural areas and explore the key factors dominating aerosol properties over these regions. Multiple-year simulations with a nested domain (horizontal resolution 0.5ox0.667o) over Europe have been carried out and compared with long-term continuous particle size distribution measurements at an urban area (Melpitz, Gernmay) and a rural area (Hyytiälä, Finland). The analysis shows that aerosol number concentration at the urban site is generally three times higher than that at the rural site. Significant diurnal and inter-monthly variations of aerosol nucleation events can be found at both sites. Because of high concentration of sulfur acid, freshly nucleated particles at urban site are much easier to grow to large-size particles rather than those at rural site. The model captures the major characteristics of aerosol size distribution observed at the two sites. Model simulation implicates that sulfur acid dominates particle growth process at Melpitz, while SOG shows significant contribution at Hyytiälä, especially during summertime. We also study the mixing state of aerosols at both the urban and rural sites, and aerosol optical property and radiative forcing in urban and rural areas are calculated to investigate the associated environment and climate impacts over these regions.

  19. Impacts of aerosol scattering on the short-wave infrared satellite observations of CO2

    NASA Astrophysics Data System (ADS)

    Fan, M.; Chen, L.; Li, S.; Tao, J.; Su, L.; Zou, M.

    2014-12-01

    Atmospheric aerosols and carbon dioxide (CO2), as two key factors driving the global climate change, have earned enormous attention from scientist around the world. One challenge for the satellite measurements of CO2 using this SWIR wavelength range (~1.6μm) is the impact of multiple scattering by aerosols and cirrus. Since the rapid economic growth and associated increase in fossil fuel consumption have caused serious particulate pollution in many regions of China, remote sensing of CO2 using SWIR band in China needs to pay more attention to the scattering properties of aerosol particles and the multiple scattering. Considering the complexity of morphological and chemical properties, aerosol particles are grouped based on a large number of TEM/SEM images, and then their scattering properties at 1.6μm band are calculated by the T-matrix method and GMM method. In this study, the Monte Carlo method is used to solve the multiple scattering problem by simulating photons transport in the scattering media. We combined this multiple scattering model with the LBLRTM as a forward radiative transfer model for studying the impact of aerosol scattering on the satellite observations of CO2 using SWIR band. Finally, based on the GOCART aerosol component products, AERONET aerosol size distribution products, CALIPSO aerosol profile products, and MODIS aerosol optical depth and surface albedo products, the monthly variability of errors in CO2 concentrations over China were calculated and analyzed. The results indicate that CO2 concentrations are overestimated in western regions of China, especially in desert areas (a maximum of ~7.08%), and those are underestimated in eastern regions (a minimum of ~-6.9%).

  20. Amazon basin ozone and aerosol: Wet season observations

    SciTech Connect

    Gregory, G.L.; Browell, E.V.; Warren, L.S.; Hudgins, C.H. )

    1990-09-20

    The tropical environment is recognized as having a major impact on global tropospheric chemistry. The data show that the wet season Amazon Basin is an effective sink for ozone and a net source for aerosols. Mixed layer ozone at 150-m altitude averaged 8.5 ppbv compared to about 18 ppbv at 3-km altitude. In addition, a negative ozone gradient (decreasing value to the surface) was observed within the mixed layer. The averaged wet season mixed layer ozone was about 7 ppbv lower than observed during the dry season. This is attributed to the enhanced convective activity associated with the wet season and the change in mixed layer photochemistry from net ozone production (dry season) to a net destruction (wet season). The net sink characteristics of the wet season mixed layer are seen throughout the troposphere of the Amazon Basin in that ozone (3- to 4-km altitude) is typically 15-25 ppbv as compared to dry season values of 30-35 ppbv. In terms of the aerosol source characteristics of the Amazon Basin, mixed layer aerosols (0.1- to 0.4-{mu}m diameter) are a factor of 5-10 higher than observed in the troposphere with mixed layer values of 100-200 aerosols/cm{sup 3}. Analyses of both tropospheric and mixed layer aerosol samples show aerosols which are multisource. Tropospheric samples have size distributions which are trimodal and show modes at aerosol diameters which suggest the aerosols are (1) of lifetimes <1 hour, (2) of lifetimes of days, and (3) mechanically generated elements (e.g., wind-blow dust). Mixed layer data show two of the three modes with no mode which represent aerosols with lifetimes of days.

  1. Quantitative determination of carbonaceous particle mixing state in Paris using single-particle mass spectrometer and aerosol mass spectrometer measurements

    NASA Astrophysics Data System (ADS)

    Healy, R. M.; Sciare, J.; Poulain, L.; Crippa, M.; Wiedensohler, A.; Prévôt, A. S. H.; Baltensperger, U.; Sarda-Estève, R.; McGuire, M. L.; Jeong, C.-H.; McGillicuddy, E.; O'Connor, I. P.; Sodeau, J. R.; Evans, G. J.; Wenger, J. C.

    2013-09-01

    Single-particle mixing state information can be a powerful tool for assessing the relative impact of local and regional sources of ambient particulate matter in urban environments. However, quantitative mixing state data are challenging to obtain using single-particle mass spectrometers. In this study, the quantitative chemical composition of carbonaceous single particles has been determined using an aerosol time-of-flight mass spectrometer (ATOFMS) as part of the MEGAPOLI 2010 winter campaign in Paris, France. Relative peak areas of marker ions for elemental carbon (EC), organic aerosol (OA), ammonium, nitrate, sulfate and potassium were compared with concurrent measurements from an Aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS), a thermal-optical OCEC analyser and a particle into liquid sampler coupled with ion chromatography (PILS-IC). ATOFMS-derived estimated mass concentrations reproduced the variability of these species well (R2 = 0.67-0.78), and 10 discrete mixing states for carbonaceous particles were identified and quantified. The chemical mixing state of HR-ToF-AMS organic aerosol factors, resolved using positive matrix factorisation, was also investigated through comparison with the ATOFMS dataset. The results indicate that hydrocarbon-like OA (HOA) detected in Paris is associated with two EC-rich mixing states which differ in their relative sulfate content, while fresh biomass burning OA (BBOA) is associated with two mixing states which differ significantly in their OA / EC ratios. Aged biomass burning OA (OOA2-BBOA) was found to be significantly internally mixed with nitrate, while secondary, oxidised OA (OOA) was associated with five particle mixing states, each exhibiting different relative secondary inorganic ion content. Externally mixed secondary organic aerosol was not observed. These findings demonstrate the range of primary and secondary organic aerosol mixing states in Paris. Examination of the temporal

  2. The Asian Dust and Aerosol Lidar Observation Network (AD-NET): Strategy and Progress

    NASA Astrophysics Data System (ADS)

    Nishizawa, Tomoaki; Sugimoto, Nobuo; Matsui, Ichiro; Shimizu, Atsushi; Higurashi, Akiko; Jin, Yoshitaka

    2016-06-01

    We have operated a ground-based lidar network AD-Net using dual wavelength (532, 1064nm) depolarization Mie lidar continuously and observed movement of Asian dust and air pollution aerosols in East Asia since 2001. This lidar network observation contributed to understanding of the occurrence and transport mechanisms of Asian dust, validation of chemical transport models, data assimilation and epidemiologic studies. To better understand the optical and microphysical properties, externally and internally mixing states, and the movements of Asian dust and airpollution aerosols, we go forward with introducing a multi-wavelength Raman lidar to the AD-Net and developing a multi-wavelength technique of HSRL in order to evaluate optical concentrations of more aerosol components. We will use this evolving AD-Net for validation of Earth-CARE satellite observation and data assimilation to evaluate emissions of air pollution and dust aerosols in East Asia. We go forward with deploying an in-situ instrument polarization optical particle counter (POPC), which can measure size distributions and non-sphericity of aerosols, to several main AD-Net sites and conducting simultaneous observation of POPC and lidar to clarify internally mixed state of Asian dust and air pollution aerosols transported from the Asian continent to Japan.

  3. Retrieval of Stratospheric Aerosol Properties from SCIAMACHY limb observations

    NASA Astrophysics Data System (ADS)

    Dörner, S.; Kühl, S.; Pukite, J.; Penning de Vries, M.; Hörmann, C.; von Savigny, C.; Wagner, T.

    2012-04-01

    Balloon-borne and aircraft measurements of stratospheric aerosol properties have been supplemented by satellite measurements since 1975 (Stratospheric Aerosol Measurement program). Ever since, the technological possibilities of satellite measurements increased steadily. Nowadays the large number of satellites provides global data sets of trace gases, clouds and aerosols. Stratospheric aerosol properties are usually determined from observations in occultation or limb geometry. Stratospheric aerosol has an important influence on the global radiation budget (e.g. after strong volcanic eruptions) and stratospheric ozone chemistry (e.g. the chlorine activation inside the polar vortex). Since the launch of SCIAMACHY on ENVISAT in 2002 measurements in limb geometry for the UV/VIS/NIR spectral range with a vertical resolution of 3.3 km at the tangent point are available. By using these measurements, profile information of stratospheric trace gases (e.g. NO2, BrO or OClO) can be retrieved. From the broad band spectral dependence of the SCIAMACHY limb measurements, also information on stratospheric aerosol properties can be derived. Pioneering studies (e.g. von Savigny et al., 2005) showed that signatures of polar stratospheric clouds and also stratospheric aerosols can be retrieved from color indices (including the near IR spectral range). In our study we make use of the color index method and additionally investigate the effects of aerosols on the whole UV/VIS/NIR spectral range. Aerosol properties are estimated by comparisons of the measured values with radiative transfer simulations. We investigate different atmospheric phenomena, e.g. volcanic eruptions (e.g. Kasatochi, 2008) or large biomass burning events (e.g. Australia, 2009). We also have a look at the spatio-temporal variation of Polar Stratospheric Clouds in the polar regions and stratospheric aerosol properties on a global scale.

  4. Aerosol and CCN properties at Princess Elisabeth station, East Antarctica: seasonality, new particle formation events and properties around precipitation events

    NASA Astrophysics Data System (ADS)

    Mangold, Alexander; Laffineur, Quentin; De Backer, Hugo; Herenz, Paul; Wex, Heike; Gossart, Alexandra; Souverijns, Niels; Gorodetskaya, Irina; Van Lipzig, Nicole

    2016-04-01

    Since 2010, several complementary ground-based instruments for measuring the aerosol composition of the Antarctic atmosphere have been operated at the Belgian Antarctic research station Princess Elisabeth, in Dronning Maud Land, East Antarctica (71.95° S, 23.35° E, 1390 m asl.). In addition, three ground-based remote sensing instruments for cloud and precipitation observations have been installed for continuous operation, including a ceilometer (cloud base height, type, vertical extent), a 24 Ghz micro-rain radar (vertical profiles of radar effective reflectivity and Doppler velocity), and a pyrometer (cloud base temperature). The station is inhabited from November to end of February and operates under remote control during the other months. In this contribution, the general aerosol and cloud condensation nuclei (CCN) properties will be described with a special focus on new particle formation events and around precipitation events. New particle formation events are important for the atmospheric aerosol budget and they also show that aerosols are not only transported to Antarctica but are also produced there, also inland. Aerosols are essential for cloud formation and therefore also for precipitation, which is the only source for mass gain of the Antarctic ice sheet. Measured aerosol properties comprise size distribution, total number, total mass concentration, mass concentration of light-absorbing aerosol and absorption coefficient and total scattering coefficient. In addition, a CCN counter has been operated during austral summers 2013/14, 2014/15 and 2015/16. The baseline total number concentration N-total was around some hundreds of particles/cm3. During new particle formation events N-total increased to some thousands of particles/cm3. Simultaneous measurements of N-total, size distribution and CCN number revealed that mostly the number of particles smaller than 100 nm increased and that the concentration of cloud condensation nuclei increased only very

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

    SciTech Connect

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

    1986-03-01

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

  6. Particle Characterization and Ice Nucleation Efficiency of Field-Collected Aerosol Particles

    NASA Astrophysics Data System (ADS)

    Wang, B.; Gilles, M. K.; Laskin, A.; Moffet, R.; Nizkorodov, S.; Roedel, T.; Sterckx, L.; Tivanski, A.; Knopf, D. A.

    2011-12-01

    Atmospheric ice formation by heterogeneous nucleation is one of the least understood processes resulting in cirrus and mixed-phase clouds which affect the global radiation budget, the hydrological cycle, and water vapor distribution. In particular, how organic aerosol affect ice nucleation is not well understood. Here we report on heterogeneous ice nucleation from particles collected during the CalNex campaign at the Caltech campus site, Pasadena, on May 19, 2010 at 6am-12pm (A2) and 12pm-6pm (A3) and May 23 at 6am-12pm (B2) and 6pm-12am (B4). The ice nucleation onsets and water uptake were determined as a function of temperature (200-273 K) and relative humidity with respect to ice (RHice). The ice nucleation efficiency was related to the particle chemical composition. Single particle characterization was provided by using computer controlled scanning electron microscopy with energy dispersive analysis of X-rays (CCSEM/EDX) and scanning transmission X-ray microscopy with near edge X-ray absorption fine structure spectroscopy (STXM/NEXAFS). The STXM/NEXAFS analysis indicates that the morning sample (A2) constitutes organic particles and organic particles with soot and inorganic inclusions. The afternoon sample (A3) is dominated by organic particles with a potentially higher degree of oxidation associated with soot. The B2 sample shows a higher number fraction of magnesium-containing particle indicative of a marine source and ~93% of the particles contained sulfur besides oxygen and carbon as derived from CCSEM/EDX analysis. The B4 sample lacks the strong marine influence and shows higher organic content. Above 230 K, we observed water uptake followed by condensation freezing at mean RH of 93-100% and 89-95% for A2 and A3, respectively. This indicates that the aged A3 particles are efficient ice nuclei (IN) for condensation freezing. Below 230 K A2 and A3 induced deposition ice nucleation between 125-155% RHice (at mean values of 134-150% RHice). The B2 and B4

  7. Chemical characterization of submicron aerosol particles collected over the Indian Ocean

    NASA Astrophysics Data System (ADS)

    Gabriel, R.; Mayol-Bracero, O. L.; Andreae, M. O.

    2002-08-01

    Submicron aerosol particles (Dp < 1 μm) were sampled with stacked filter units on the National Center for Atmospheric Research (NCAR) Hercules C-130 aircraft during February-March 1999 as a contribution to the Indian Ocean Experiment (INDOEX). We determined the vertical and spatial distribution of the major aerosol components (NH4+, Na+, K+, Mg2+, Ca2+, methyl sulfonic acid, Cl-, NO3-, SO42-, oxalate, organic carbon, and black carbon) over the Indian Ocean to examine the role of pollution aerosols on indirect and direct radiative forcing. High pollution levels were observed over the entire northern Indian Ocean down to the Intertropical Convergence Zone (ITCZ) located between the equator and 10°S. In the northern part of the Indian Ocean (5°-15°N, 66°-73°E), high concentrations of carbonaceous aerosol and pollution-derived inorganic species were found in a layer extending from the sea surface to about 3.5 km asl. In this layer, the average mass concentration of all aerosol species detected by our technique ranged between 7 and 34 μg m-3, comparable to pollution levels observed in industrialized regions. In the Southern Hemisphere (1°-9°S, 66°-73°E), the aerosol concentrations rapidly declined to remote background levels of about 2 μg m-3. The concentrations of non-sea-salt sulfate (the main light scattering component) ranged from maximum values of 12.7 μg m-3 in the Northern Hemisphere to 0.2 μg m-3 in the Southern Hemisphere. Carbonaceous aerosol contributes between 40% and 60% to the fine aerosol mass of all determined components. An unusually high fraction of black carbon (up to 16% in the polluted areas) is responsible for its high light absorption coefficient.

  8. Single-particle light-scattering measurement: photochemical aerosols and atmospheric particulates.

    PubMed

    Phillips, D T; Wyatt, P J

    1972-09-01

    The use of single-particle light-scattering measurements to determine the origin of atmospheric hazes has been explored by measurement of laboratory aerosols, field samples, and computer analysis of the light-scattering data. The refractive index of measured spherical particles 800 nm to 1000 nm in diameter was determined within 2%. For particles of diameter less than 500 nm the measurement of absolute scattering intensity is required for complete analysis. Distinctive nonspherical and absorbing particles were observed both in automotive exhaust and atmospheric samples. Electrostatic suspension of atmospheric particulates is demonstrated to provide a practical approach to optical measurement of single particles. The technique may be used to calibrate optical particle counters or identify particles with unique shape or refractive index. PMID:20119285

  9. Elucidating determinants of aerosol composition through particle-type-based receptor modeling

    NASA Astrophysics Data System (ADS)

    McGuire, M. L.; Jeong, C.-H.; Slowik, J. G.; Chang, R. Y.-W.; Corbin, J. C.; Lu, G.; Mihele, C.; Rehbein, P. J. G.; Sills, D. M. L.; Abbatt, J. P. D.; Brook, J. R.; Evans, G. J.

    2011-03-01

    An aerosol time-of-flight mass spectrometer (ATOFMS) was deployed at a semi-rural site in Southern Ontario to characterize the size and chemical composition of individual particles. Particle-type-based receptor modelling of these data was used to investigate the determinants of aerosol chemical composition in this region. Individual particles were classified into particle-types and positive matrix factorization (PMF) was applied to their temporal trends to separate and cross-apportion particle-types to factors. The extent of chemical processing for each factor was assessed by evaluating the internal and external mixing state of the characteristic particle-types. The nine factors identified helped to elucidate the coupled interactions of these determinants. Nitrate-laden dust was found to be the dominant type of locally emitted particles measured by ATOFMS. Several factors associated with aerosol transported to the site from intermediate local-to-regional distances were identified: the Organic factor was associated with a combustion source to the north-west; the ECOC Day factor was characterized by nearby local-to-regional carbonaceous emissions transported from the south-west during the daytime; and the Fireworks factor consisted of pyrotechnic particles from the Detroit region following holiday fireworks displays. Regional aerosol from farther emissions sources were reflected through three factors: two biomass burning factors and a highly chemically processed long range transport factor. The biomass burning factors were separated by PMF due to differences in chemical processing which were caused in part by the passage of two thunderstorm gust fronts with different air mass histories. The remaining two factors, ECOC Night and Nitrate Background, represented the night-time partitioning of nitrate to pre-existing particles of different origins. The distinct meteorological conditions observed during this month-long study in the summer of 2007 provided a unique range

  10. Elucidating determinants of aerosol composition through particle-type-based receptor modeling

    NASA Astrophysics Data System (ADS)

    McGuire, M. L.; Jeong, C.-H.; Slowik, J. G.; Chang, R. Y.-W.; Corbin, J. C.; Lu, G.; Mihele, C.; Rehbein, P. J. G.; Sills, D. M. L.; Abbatt, J. P. D.; Brook, J. R.; Evans, G. J.

    2011-08-01

    An aerosol time-of-flight mass spectrometer (ATOFMS) was deployed at a semi-rural site in southern Ontario to characterize the size and chemical composition of individual particles. Particle-type-based receptor modelling of these data was used to investigate the determinants of aerosol chemical composition in this region. Individual particles were classified into particle-types and positive matrix factorization (PMF) was applied to their temporal trends to separate and cross-apportion particle-types to factors. The extent of chemical processing for each factor was assessed by evaluating the internal and external mixing state of the characteristic particle-types. The nine factors identified helped to elucidate the coupled interactions of these determinants. Nitrate-laden dust was found to be the dominant type of locally emitted particles measured by ATOFMS. Several factors associated with aerosol transported to the site from intermediate local-to-regional distances were identified: the Organic factor was associated with a combustion source to the north-west; the ECOC Day factor was characterized by nearby local-to-regional carbonaceous emissions transported from the south-west during the daytime; and the Fireworks factor consisted of pyrotechnic particles from the Detroit region following holiday fireworks displays. Regional aerosol from farther emissions sources was reflected through three factors: two Biomass Burning factors and a highly chemically processed Long Range Transport factor. The Biomass Burning factors were separated by PMF due to differences in chemical processing which were in part elucidated by the passage of two thunderstorm gust fronts with different air mass histories. The remaining two factors, ECOC Night and Nitrate Background, represented the night-time partitioning of nitrate to pre-existing particles of different origins. The distinct meteorological conditions observed during this month-long study in the summer of 2007 provided a unique

  11. Physical and Chemical Characterization of Particles in the Upper Troposphere and Lower Stratosphere: Microanalysis of Aerosol Impactor Samples

    NASA Technical Reports Server (NTRS)

    Sheridan, Patrick J.

    1999-01-01

    Herein is reported activities to support the characterization of the aerosol in the upper troposphere (UT) and lower stratosphere (LS) collected during the Airborne Southern Hemisphere Ozone Experiment/Measurements for Assessing the Effects of Stratospheric Aircraft (ASHOE/MAESA) missions in 1994. Through a companion proposal, another group was to measure the size distribution of aerosols in the 0.008 to 2 micrometer diameter range and to collect for us impactor samples of particles larger than about 0.02 gm. In the first year, we conducted laboratory studies related to particulate deposition patterns on our collection substrates, and have performed the analysis of many ASHOE/MAESA aerosol samples from 1994 using analytical electron microscopy (AEM). We have been building an "aerosol climatology" with these data that documents the types and relative abundances of particles observed at different latitudes and altitudes. The second year (and non-funded extension periods) saw continued analyses of impactor aerosol samples, including more ASHOE/MAESA samples, some northern hemisphere samples from the NASA Stratospheric Photochemistry Aerosols and Dynamics Expedition (SPADE) program for comparison, and a few aerosol samples from the NASA Stratospheric TRacers of Atmospheric Transport (STRAT) program. A high-resolution field emission microscope was used for the analysis and re-analysis of a number of samples to determine if this instrument was superior in performance to our conventional electron microscope. In addition, some basic laboratory studies were conducted to determine the minimum detectable and analyzable particle size for different types of aerosols. In all, 61 aerosol samples were analyzed, with a total of over 30,000 individual particle analyses. In all analyzed samples, sulfate particles comprised the major aerosol number fraction. It must be stressed that particles composed of more than one species, for example sulfate and organic carbon, were classified

  12. THEMIS Observations of Atmospheric Aerosol Optical Depth

    NASA Technical Reports Server (NTRS)

    Smith, Michael D.; Bandfield, Joshua L.; Christensen, Philip R.; Richardson, Mark I.

    2003-01-01

    The Mars Odyssey spacecraft entered into Martian orbit in October 2001 and after successful aerobraking began mapping in February 2002 (approximately Ls=330 deg.). Images taken by the Thermal Emission Imaging System (THEMIS) on-board the Odyssey spacecraft allow the quantitative retrieval of atmospheric dust and water-ice aerosol optical depth. Atmospheric quantities retrieved from THEMIS build upon existing datasets returned by Mariner 9, Viking, and Mars Global Surveyor (MGS). Data from THEMIS complements the concurrent MGS Thermal Emission Spectrometer (TES) data by offering a later local time (approx. 2:00 for TES vs. approx. 4:00 - 5:30 for THEMIS) and much higher spatial resolution.

  13. Evolution of the Physicochemical and Activation Properties of Aerosols within Smoke Plumes during the Biomass Burning Observation Project (BBOP)

    NASA Astrophysics Data System (ADS)

    Tomlinson, J. M.; Mei, F.; Wang, J.; Comstock, J. M.; Hubbe, J. M.; Pekour, M. S.; Shilling, J. E.; Fortner, E.; Chand, D.; Sedlacek, A. J., III; Kleinman, L. I.; Senum, G.; Schmid, B.

    2014-12-01

    Biomass burning from wildfires and controlled agricultural burns are known to be a major source of fine particles and organic aerosols at northern temperate latitudes during the summer months. However, the evolution of the physicochemical properties of the aerosol during transport and the potential impact of this evolution on cloud condensation nuclei (CCN) activity has rarely been studied for these events. During the DOE-sponsored Biomass Burning Observation Project (BBOP) conducted in the summer and fall of 2013, over 30 research flights sampled biomass burning plumes from wildfires in the Northwestern United States and agricultural burns in the Mid-South region of the United States. A large suite of instruments aboard the DOE G-1 (Gulfstream-1) measured the chemical, physical, and optical properties of biomass burning aerosol with an emphasis on black carbon. A Fast Integrated Mobility Spectrometer (FIMS), Ultra High Sensitivity Aerosol Spectrometer - Airborne (UHSAS-A), and Passive Cavity Aerosol Spectrometer (PCASP) were used to measure the aerosol size distribution from 15 - 3,000 nm at 1-Hz. A dual column CCN counter measured the CCN number concentration at supersaturations of 0.25% and 0.50% at a time resolution of 1-Hz and the aerosol chemical composition was measured using a soot particle aerosol mass spectrometer (SP-AMS, Aerodyne, Inc). The SP-AMS was operated in two modes: (i) as a traditional high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS, Aerodyne Inc.), which measured chemical composition of non-refractory aerosols and (ii) as the SP-AMS which measured chemical composition of the refractory black carbon-containing (rBC) particle coating and rBC aerosol mass. Utilizing the aforementioned measurements, a CCN closure study is used to investigate the emitted aerosol hygroscopicity, the evolution of the physicochemical properties of the aerosol, and the potential impacts on cloud microphysics from the different fuel sources.

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  15. Mass concentration and mineralogical characteristics of aerosol particles collected at Dunhuang during ACE-Asia

    NASA Astrophysics Data System (ADS)

    Shen, Z. X.; Cao, J. J.; Li, X. X.; Okuda, T.; Wang, Y. Q.; Zhang, X. Y.

    2006-03-01

    Measurements were performed in spring 2001 and 2002 to determine the characteristics of soil dust in the Chinese desert region of Dunhuang, one of the ground sites of the Asia-Pacific Regional Aerosol Characterization Experiment (ACE-Asia). The mean mass concentrations of total suspended particle matter during the spring of 2001 and 2002 were 317 mu g m(-3) and 307 mu g m(-3) respectively. Eleven dust storm events were observed with a mean aerosol concentration of 1095 mu g m(-3), while the non-dusty days with calm or weak wind speed had a background aerosol loading of 196 mu g m(-3) on average in the springtime. The main minerals detected in the aerosol samples by X-ray diffraction were illite, kaolinite, chlorite, quartz, feldspar, calcite and dolomite. Gypsum, halite and amphibole were also detected in a few samples. The mineralogical data also show that Asian dust is characterized by a kaolinite to chlorite (K/C) ratio lower than 1 whereas Saharan dust exhibits a K/C ratio larger than 2. Air mass back- trajectory analysis show that three families of pathways are associated with the aerosol particle transport to Dunhuang, but these have similar K/C ratios, which further demonstrates that the mineralogical characteristics of Asian dust are different from African dust.

  16. Graphical techniques for interpreting the composition of individual aerosol particles

    NASA Astrophysics Data System (ADS)

    Yuan, Hui; Rahn, Kenneth A.; Zhuang, Guoshun

    A graphical technique that uses X- Y and ternary plots is presented for interpreting elemental data for individual aerosol particles. By revealing the multiple functional relationships between the elements, it offers more insight into the groups of particles and the transitions between them than traditional techniques such as factor analysis and cluster analysis alone are able to. For a sample of dust storm aerosol from Beijing in March 2002, X-Y plots revealed areas, lines, and "dots" that represented clays, smooth transitions to asymptotes of pure single-component minerals, and pure minor minerals or special particles, respectively. Ternary plots further revealed ratios of elements and potential minerals. Careful use of cluster analysis revealed subgroups of particles that were not separated by clear borders. The dust storm had three major components, clay/quartz (Al 2O 3, SiO 2, etc.), basic calcium (CaO, CaCO 3), and salts (sulfate, phosphate, chloride). Some sulfates, including CaSO 4 and (NH 4) xH 2-xSO 4, were mixed with the quartz and clay. A five-step sequence that combines graphics, basic statistics, cluster analysis, and SEM photography seems to extract the maximum information from suites of single particles.

  17. Heterogeneous Ice Nucleation on Kaolinite Particles, Particle Surrogates of HUmic-Like Substances (HULIS), and Organics-Containing Urban Aerosols

    NASA Astrophysics Data System (ADS)

    Wang, B.; Knopf, D. A.

    2009-12-01

    Aerosol particles can affect the global radiation budget through aerosol-cloud interactions by acting as cloud condensation nuclei and ice nuclei (IN) thereby inducing new clouds and/or modifying the radiative properties of existing clouds. This study presents heterogeneous ice nucleation data as a function of particle temperature and relative humidity with respect to ice (RHice) for laboratory generated kaolinite particles, leonardite and fulvic acid particles serving as surrogates for aerosols composed of HULIS, and organics-containing urban aerosols collected during the MILAGRO (Mexico City) campaign. These experiments are conducted using an improved version of a previously developed ice nucleation cell coupled to an optical microscope which allows to control particle temperatures between 200-300 K and corresponding atmospherically relevant RHice. Micrometer-sized particles are deposited onto a hydrophobic substrate and are placed in the nucleation cell. To validate the experimental approach and quality of substrates, ice nucleation experiments were performed 1. on plain sample substrates and 2. using a well studied IN: kaolinite particles. The results corroborate that kaolinite particles are efficient IN inducing ice nucleation at 102-120% RHice via deposition mode at temperatures between 200 and 245 K, in agreement with previous studies. The ice nucleation efficiency of leonardite and fulvic acid particles with median diameters of 2-3 µm is determined. Leonardite particles nucleate ice via deposition mode at 120-140% RHice for temperatures between 200 and 240 K with the minimum RHice threshold observed at 220 K. Fulvic acid particles nucleate ice via deposition mode at 135-150% RHice for temperatures between 200 and 230 K with the minimum RHice threshold determined at 216 K. The fulvic acid particles take up water at RH>95% for temperatures between 235 and 250 K. The contact angle derived from experimentally determined heterogeneous ice nucleation rate

  18. Effect of typhoon on atmospheric aerosol particle pollutants accumulation over Xiamen, China.

    PubMed

    Yan, Jinpei; Chen, Liqi; Lin, Qi; Zhao, Shuhui; Zhang, Miming

    2016-09-01

    Great influence of typhoon on air quality has been confirmed, however, rare data especially high time resolved aerosol particle data could be used to establish the behavior of typhoon on air pollution. A single particle aerosol spectrometer (SPAMS) was employed to characterize the particles with particle number count in high time resolution for two typhoons of Soulik (2013) and Soudelor (2015) with similar tracks. Three periods with five events were classified during the whole observation time, including pre - typhoon (event 1 and event 2), typhoon (event 3 and event 4) and post - typhoon (event 5) based on the meteorological parameters and particle pollutant properties. First pollutant group appeared during pre-typhoon (event 2) with high relative contributions of V - Ni rich particles. Pollution from the ship emissions and accumulated by local processes with stagnant meteorological atmosphere dominated the formation of the pollutant group before typhoon. The second pollutant group was present during typhoon (event 3), while typhoon began to change the local wind direction and increase wind speed. Particle number count reached up to the maximum value. High relative contributions of V - Ni rich and dust particles with low value of NO3(-)/SO4(2-) was observed during this period, indicating that the pollutant group was governed by the combined effect of local pollutant emissions and long-term transports. The analysis of this study sheds a deep insight into understand the relationship between the air pollution and typhoon. PMID:27295441

  19. PARAGON: A Systematic, Integrated Approach to Aerosol Observation and Modeling

    NASA Technical Reports Server (NTRS)

    Diner, David J.; Kahn, Ralph A.; Braverman, Amy J.; Davies, Roger; Martonchik, John V.; Menzies, Robert T.; Ackerman, Thomas P.; Seinfeld, John H.; Anderson, Theodore L.; Charlson, Robert J.; Bosenberg, Jens; Collins, William D.; Rasch, Philip J.; Holben, Brent N.; Hostetler, Chris A.; Wielicki, Bruce A.; Miller, Mark A.; Schwartz, Stephen E.; Ogren, John A.; Penner, Joyce E.; Stephens, Graeme L.; Torres, Omar; Travis, Larry D.; Yu, Bin

    2004-01-01

    Aerosols are generated and transformed by myriad processes operating across many spatial and temporal scales. Evaluation of climate models and their sensitivity to changes, such as in greenhouse gas abundances, requires quantifying natural and anthropogenic aerosol forcings and accounting for other critical factors, such as cloud feedbacks. High accuracy is required to provide sufficient sensitivity to perturbations, separate anthropogenic from natural influences, and develop confidence in inputs used to support policy decisions. Although many relevant data sources exist, the aerosol research community does not currently have the means to combine these diverse inputs into an integrated data set for maximum scientific benefit. Bridging observational gaps, adapting to evolving measurements, and establishing rigorous protocols for evaluating models are necessary, while simultaneously maintaining consistent, well understood accuracies. The Progressive Aerosol Retrieval and Assimilation Global Observing Network (PARAGON) concept represents a systematic, integrated approach to global aerosol Characterization, bringing together modern measurement and modeling techniques, geospatial statistics methodologies, and high-performance information technologies to provide the machinery necessary for achieving a comprehensive understanding of how aerosol physical, chemical, and radiative processes impact the Earth system. We outline a framework for integrating and interpreting observations and models and establishing an accurate, consistent and cohesive long-term data record.

  20. Airborne Observations of Aerosol Emissions from F-16 Aircraft

    NASA Technical Reports Server (NTRS)

    Anderson, B. E.; Cofer, W. R.; McDougal, D. S.

    1999-01-01

    We presented results from the SASS Near-Field Interactions Flight (SNIF-III) Experiment which was conducted during May and June 1997 in collaboration with the Vermont and New Jersey Air National Guard Units. The project objectives were to quantify the fraction of fuel sulfur converted to S(VI) species by jet engines and to gain a better understanding of particle formation and growth processes within aircraft wakes. Size and volatility segregated aerosol measurements along with sulfur species measurements were recorded in the exhaust of F-16 aircraft equipped with F-100 engines burning fuels with a range of fuel S concentrations at different altitudes and engine power settings. A total of 10 missions were flown in which F-16 exhaust plumes were sampled by an instrumented T-39 Sabreliner aircraft. On six of the flights, measurements were obtained behind the same two aircraft, one burning standard JP-8 fuel and the other either approximately 28 ppm or 1100 ppm S fuel or an equal mixture of the two (approximately 560 ppm S). A pair of flights was conducted for each fuel mixture, one at 30,000 ft altitude and the other starting at 35,000 ft and climbing to higher altitudes if contrail conditions were not encountered at the initial flight level. In each flight, the F-16s were operated at two power settings, approx. 80% and full military power. Exhaust emissions were sampled behind both aircraft at each flight level, power setting, and fuel S concentration at an initial aircraft separation of 30 m, gradually widening to about 3 km. Analyses of the aerosol data in the cases where fuel S was varied suggest results were consistent with observations from project SUCCESS, i.e., a significant fraction of the fuel S was oxidized to form S(VI) species and volatile particle emission indices (EIs) in comparably aged plumes exhibited a nonlinear dependence upon the fuel S concentration. For the high sulfur fuel, volatile particle EIs in 10-second-old-plumes were 2 to 3 x 10 (exp 17

  1. Hygroscopic properties of smoke-generated organic aerosol particles emitted in the marine atmosphere

    NASA Astrophysics Data System (ADS)

    Wonaschütz, A.; Coggon, M.; Sorooshian, A.; Modini, R.; Frossard, A. A.; Ahlm, L.; Mülmenstädt, J.; Roberts, G. C.; Russell, L. M.; Dey, S.; Brechtel, F. J.; Seinfeld, J. H.

    2013-10-01

    During the Eastern Pacific Emitted Aerosol Cloud Experiment (E-PEACE), a plume of organic aerosol was produced by a smoke generator and emitted into the marine atmosphere from aboard the R/V Point Sur. In this study, the hygroscopic properties and the chemical composition of the plume were studied at plume ages between 0 and 4 h in different meteorological conditions. In sunny conditions, the plume particles had very low hygroscopic growth factors (GFs): between 1.05 and 1.09 for 30 nm and between 1.02 and 1.1 for 150 nm dry size at a relative humidity (RH) of 92%, contrasted by an average marine background GF of 1.6. New particles were produced in large quantities (several 10 000 cm-3), which lead to substantially increased cloud condensation nuclei (CCN) concentrations at supersaturations between 0.07 and 0.88%. Ratios of oxygen to carbon (O : C) and water-soluble organic mass (WSOM) increased with plume age: from < 0.001 to 0.2, and from 2.42 to 4.96 μg m-3, respectively, while organic mass fractions decreased slightly (~ 0.97 to ~ 0.94). High-resolution aerosol mass spectrometer (AMS) spectra show that the organic fragment m/z 43 was dominated by C2H3O+ in the small, new particle mode and by C3H7+ in the large particle mode. In the marine background aerosol, GFs for 150 nm particles at 40% RH were found to be enhanced at higher organic mass fractions: an average GF of 1.06 was observed for aerosols with an organic mass fraction of 0.53, and a GF of 1.04 for an organic mass fraction of 0.35.

  2. Airborne observations of regional variation in fluorescent aerosol across the United States

    NASA Astrophysics Data System (ADS)

    Perring, A. E.; Schwarz, J. P.; Baumgardner, D.; Hernandez, M. T.; Spracklen, D. V.; Heald, C. L.; Gao, R. S.; Kok, G.; McMeeking, G. R.; McQuaid, J. B.; Fahey, D. W.

    2015-02-01

    Airborne observations of fluorescent aerosol were made aboard an airship during CloudLab, a series of flights that took place in September and October of 2013 and covered a wideband of longitude across the continental U.S. between Florida and California and between 28 and 37 N latitudes. Sampling occurred from near the surface to 1000 m above the ground. A Wideband Integrated Bioaerosol Sensor (WIBS-4) measured average concentrations of supermicron fluorescent particles aloft (1 µm to 10 µm), revealing number concentrations ranging from 2.1 ± 0.8 to 8.7 ± 2.2 × 104 particles m-3 and representing up to 24% of total supermicron particle number. We observed distinct variations in size distributions and fluorescent characteristics in different regions, and attribute these to geographically diverse bioaerosol. Fluorescent aerosol detected in the east is largely consistent with mold spores observed in a laboratory setting, while a shift to larger sizes associated with different fluorescent patterns is observed in the west. Fluorescent bioaerosol loadings in the desert west were as high as those near the Gulf of Mexico, suggesting that bioaerosol is a substantial component of supermicron aerosol both in humid and arid environments. The observations are compared to model fungal and bacterial loading predictions, and good agreement in both particle size and concentrations is observed in the east. In the west, the model underestimated observed concentrations by a factor between 2 and 4 and the prescribed particle sizes are smaller than the observed fluorescent aerosol. A classification scheme for use with WIBS data is also presented.

  3. A new technique for measuring aerosols with moonlight observations and a sky background model

    NASA Astrophysics Data System (ADS)

    Jones, Amy; Noll, Stefan; Kausch, Wolfgang; Kimeswenger, Stefan; Szyszka, Ceszary; Unterguggenberger, Stefanie

    2014-05-01

    moonlight model is designed for the average atmospheric conditions at Cerro Paranal. The Mie scattering is calculated for the average distribution of aerosol particles, but this input can be modified. We can avoid the airglow emission lines, and near full Moon the airglow continuum can be ignored. In the case study, by comparing the scattered moonlight for the various angles and wavelengths along with the extinction curve from the standard stars, we can iteratively find the optimal aerosol size distribution for the time of observation. We will present this new technique, the results from this case study, and how it can be implemented for investigating aerosols using the X-Shooter archive and other astronomical archives.

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

    NASA Astrophysics Data System (ADS)

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

    2008-12-01

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

  5. Optical properties of internally mixed aerosol particles composed of dicarboxylic acids and ammonium sulfate.

    PubMed

    Freedman, Miriam A; Hasenkopf, Christa A; Beaver, Melinda R; Tolbert, Margaret A

    2009-12-01

    We have investigated the optical properties of internally mixed aerosol particles composed of dicarboxylic acids and ammonium sulfate using cavity ring-down aerosol extinction spectroscopy at a wavelength of 532 nm. The real refractive indices of these nonabsorbing species were retrieved from the extinction and concentration of the particles using Mie scattering theory. We obtain refractive indices for pure ammonium sulfate and pure dicarboxylic acids that are consistent with literature values, where they exist, to within experimental error. For mixed particles, however, our data deviates significantly from a volume-weighted average of the pure components. Surprisingly, the real refractive indices of internal mixtures of succinic acid and ammonium sulfate are higher than either of the pure components at the highest organic weight fractions. For binary internal mixtures of oxalic or adipic acid with ammonium sulfate, the real refractive indices of the mixtures are approximately the same as ammonium sulfate for all organic weight fractions. Various optical mixing rules for homogeneous and slightly heterogeneous systems fail to explain the experimental real refractive indices. It is likely that complex particle morphologies are responsible for the observed behavior of the mixed particles. Implications of our results for atmospheric modeling and aerosol structure are discussed. PMID:19877658

  6. A preliminary analysis of the surface chemistry of atmospheric aerosol particles in a typical urban area of Beijing.

    PubMed

    Zhang, Zhengzheng; Li, Hong; Liu, Hongyan; Ni, Runxiang; Li, Jinjuan; Deng, Liqun; Lu, Defeng; Cheng, Xueli; Duan, Pengli; Li, Wenjun

    2016-09-01

    Atmospheric aerosol particle samples were collected using an Ambient Eight Stage (Non-Viable) Cascade Impactor Sampler in a typical urban area of Beijing from 27th Sep. to 5th Oct., 2009. The surface chemistry of these aerosol particles was analyzed using Static Time of Flight-Secondary Ion Mass Spectrometry (Static TOF-SIMS). The factors influencing surface compositions were evaluated in conjunction with the air pollution levels, meteorological factors, and air mass transport for the sampling period. The results show that a variety of organic ion groups and inorganic ions/ion groups were accumulated on the surfaces of aerosol particles in urban areas of Beijing; and hydrophobic organic compounds with short- or middle-chain alkyl as well as hydrophilic secondary inorganic compounds were observed. All these compounds have the potential to affect the atmospheric behavior of urban aerosol particles. PM1.1-2.1 and PM3.3-4.7 had similar elements on their surfaces, but some molecules and ionic groups demonstrated differences in Time of Flight-Secondary Ion Mass Spectrometry spectra. This suggests that the quantities of elements varied between PM1.1-2.1 and PM3.3-4.7. In particular, more intense research efforts into fluoride pollution are required, because the fluorides on aerosol surfaces have the potential to harm human health. The levels of air pollution had the most significant influence on the surface compositions of aerosol particles in our study. Hence, heavier air pollution was associated with more complex surface compositions on aerosol particles. In addition, wind, rainfall, and air masses from the south also greatly influenced the surface compositions of these urban aerosol particles. PMID:27593274

  7. Influence of water uptake on the aerosol particle light scattering at remote sites (Invited)

    NASA Astrophysics Data System (ADS)

    Zieger, P.; Fierz-Schmidhauser, R.; Baltensperger, U.; Weingartner, E.

    2013-12-01

    Since ambient aerosol particles experience hygroscopic growth at enhanced relative humidity (RH), their microphysical and optical properties - especially the aerosol light scattering - are also strongly dependent on RH. The knowledge of this RH effect is of importance for climate forcing calculations or for the comparison of remote sensing with in-situ measurements because in the field aerosol in-situ measurements are often performed under dry conditions. The scattering enhancement factor f(RH,λ) is the key parameter to describe this effect of water uptake on the particle light scattering. It is defined as the particle light scattering coefficient σ(RH) at a certain RH and wavelength λ divided by its dry value. Here, we will present results from two remote sites: the Jungfraujoch located at 3580 m a.s.l. in the Swiss Alps and from Zeppelin station located at 78.5°N in the Arctic (Fierz-Schmidhauser et al., 2010; Zieger et al., 2010). Various aerosol optical and microphysical parameters were recorded at these sites using in-situ and remote sensing techniques. The scattering enhancement varied largely from very low values of f(RH=85%,λ=550 nm) around 1.28 for mineral dust transported to the Jungfraujoch to 3.41 for pristine Arctic aerosol. Compensating effects of size and hygroscopicity were observed in the Arctic, i.e. small but less hygroscopic particles eventually had the same magnitude in f(RH) as large but more hygroscopic particles like sea salt. Closure studies and Mie simulations showed that both size and chemical composition determine the magnitude of f(RH). The f(RH)-values from the two remote sites will also be related to values measured at other maritime, rural, and continental sites in Europe (Zieger et al., 2013). Active and passive remote sensing techniques were used to study the vertical distribution of aerosol optical properties around Jungfraujoch. Part of these in-situ measured parameters, together with the RH-dependent σ(RH) were used to

  8. Aerosol variability and atmospheric transport in the Himalayan region from CALIOP 2007-2010 observations

    NASA Astrophysics Data System (ADS)

    Bucci, S.; Cagnazzo, C.; Cairo, F.; Di Liberto, L.; Fierli, F.

    2014-05-01

    This work quantifies the spatial distribution of different aerosol types, their seasonal variability and sources.The analysis of four years of CALIOP (Cloud-Aerosol LIdar with Orthogonal Polarization) vertically resolved aerosol data allows the identification of spatial patterns of desert dust and carbonaceous particles in different atmospheric layers. Clusters of Lagrangian back trajectories highlight the transport pathways from source regions during the dusty spring season. The analysis shows a prevalence of dust; at low heights it occurs frequently (up to 70% of available observations) and is distributed north of the Tibetan Plateau with a main contribution from the Gobi and Taklamakan deserts, and west of the Tibetan Plateau, originating from the deserts of southwest Asia and advected by the Westerlies. Above the Himalayas the dust amount is minor but still not negligible (occurrence around 20%) and mainly affected by the transport from more distant deserts sources (Sahara and Arabian Peninsula). Carbonaceous aerosol, produced mainly in northern India and eastern China, is subject to shorter-range transport and is indeed observed closer to the sources, while there is a limited amount reaching the top of the plateau. Data analysis reveals a clear seasonal variability in the frequencies of occurrence for the main aerosol types; dust is regulated principally by the monsoon dynamics, with maximal occurrence in spring. We also highlight relevant interannual differences, showing a larger presence of aerosol in the region during 2007 and 2008. The characterization of the aerosol spatial and temporal distribution in terms of observational frequency is a key piece of information that can be directly used for the evaluation of global aerosol models.

  9. Evidence for the role of organics in aerosol particle formation under atmospheric conditions

    NASA Astrophysics Data System (ADS)

    Baltensperger, Urs

    2010-05-01

    New particle formation in the atmosphere is an important parameter in governing the radiative forcing of atmospheric aerosols. However, detailed nucleation mechanisms remain still ambiguous, as laboratory data have so far not been successful in explaining atmospheric nucleation. We investigated the formation of new particles in a smog chamber simulating the photochemical formation of H2SO4 and organic condensable species. Nucleation occurs at H2SO4 concentrations similar to the ones found in the ambient atmosphere during nucleation events. The measured particle formation rates are proportional to the product of the concentrations of H2SO4 and an organic molecule. This suggests that only one H2SO4 molecule and one organic molecule are involved in the rate limiting step of the observed nucleation process. Parameterizing this process in a global aerosol model results in substantially better agreement with ambient observations compared to control runs. Reference: Axel Metzger, Bart Verheggen, Josef Dommen, Jonathan Duplissy, Andre S. H. Prevot, Ernest Weingartner, Ilona Riipinen, Markku Kulmala, Dominick V. Spracklen, Kenneth S. Carslaw, and Urs Baltensperger, Evidence for the role of organics in aerosol particle formation under atmospheric conditions, Proc. Natl. Acad. Sci. USA, 107 (2010), www.pnas.org/cgi/doi/10.1073/pnas.0911330107.

  10. Reactive uptake of N2O5 by aerosol particles containing mixtures of humic acid and ammonium sulfate.

    PubMed

    Badger, Claire L; Griffiths, Paul T; George, Ingrid; Abbatt, Jonathan P D; Cox, R Anthony

    2006-06-01

    The kinetics of reactive uptake of N2O5 on submicron aerosol particles containing humic acid and ammonium sulfate has been investigated as a function of relative humidity (RH) and aerosol composition using a laminar flow reactor coupled with a differential mobility analyzer (DMA) to characterize the aerosol. For single-component humic acid aerosol the uptake coefficient, gamma, was found to increase from 2 to 9 x 10(-4) over the range 25-75% RH. These values are 1-2 orders of magnitude below those typically observed for single-component sulfate aerosols (Phys. Chem. Chem. Phys. 2003, 5, 3453-3463;(1) Atmos. Environ. 2000, 34, 2131-2159(2)). For the mixed aerosols, gamma was found to decrease with increasing humic acid mass fraction and increase with increasing RH. For aerosols containing only 6% humic acid by dry mass, a decrease in reactivity of more than a factor of 2 was observed compared with the case for single-component ammonium sulfate. The concentration of liquid water in the aerosol droplets was calculated using the aerosol inorganic model (for the ammonium sulfate component) and a new combined FTIR-DMA system (for the humic acid component). Analysis of the uptake coefficients using the water concentration data shows that the change in reactivity cannot be explained by the change in water content alone. We suggest that, due to its surfactant properties, the main effect of the humic acid is to reduce the mass accommodation coefficient for N2O5 at the aerosol particle surface. This has implications for the use of particle hygroscopicity data for predictions of the rate of N2O5 hydrolysis. PMID:16722713

  11. Time evolution and emission factors of aerosol particles from day and night time savannah fires

    NASA Astrophysics Data System (ADS)

    Vakkari, Ville; Beukes, Johan Paul; Tiitta, Petri; Venter, Andrew; Jaars, Kerneels; Josipovic, Miroslav; van Zyl, Pieter; Kulmala, Markku; Laakso, Lauri

    2013-04-01

    The largest uncertainties in the current global climate models originate from aerosol particle effects (IPCC, 2007) and at the same time aerosol particles also pose a threat to human health (Pope and Dockery, 2006). In southern Africa wild fires and prescribed burning are one of the most important sources of aerosol particles, especially during the dry season from June to September (e.g. Swap et al., 2003; Vakkari et al., 2012). The aerosol particle emissions from savannah fires in southern Africa have been studied in several intensive campaigns such as SAFARI 1992 and 2000 (Swap et al., 2003). However, all previous measurements have been carried out during the daytime, whereas most of the prescribed fires in southern Africa are lit up only after sunset. Furthermore, the previous campaigns followed the plume evolution for up to one hour after emission only. In this study, combining remote sensing fire observations to ground-based long-term measurements of aerosol particle and trace gas properties at the Welgegund measurement station (www.welgegund.org), we have been able to follow the time evolution of savannah fire plumes up to several hours in the atmosphere. For the first time the aerosol particle size distribution measurements in savannah fire plumes cover both day and night time plumes and also the ultrafine size range below 100 nm. During the period from May 20th 2010 to April 15th 2012 altogether 61 savannah fire plumes were observed at Welgegund. The evolution of the aerosol size distribution remained rapid for at least five hours after the fire: during this period the growth rate of the aerosol particle count mean diameter (size range 12 to 840 nm) was 24 nm h-1 for daytime plumes and 8 nm h-1 for night time plumes. The difference in the day and night time growth rate shows that photochemical reactions significantly increase the condensable vapour concentration in the plume. Furthermore, the condensable vapour concentration was found to affect both the

  12. Radiative Impact of Observed and Simulated Aerosol Layers Over the East Coast of North America

    NASA Astrophysics Data System (ADS)

    Berg, L. K.; Fast, J. D.; Burton, S. P.; Chand, D.; Comstock, J. M.; Ferrare, R. A.; Hair, J. W.; Hostetler, C. A.; Hubbe, J. M.; Kassianov, E.; Rogers, R. R.; Sedlacek, A. J., III; Shilling, J. E.; Tomlinson, J. M.; Wilson, J. M.; Zelenyuk, A.

    2014-12-01

    The vertical distribution of particles in the atmospheric column can have a large impact on the radiative forcing and cloud microphysics. A recent climatology constructed using data collected by the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) suggests elevated layers of aerosol are quite common near the North American east coast during both winter and summer. The Two-Column Aerosol Project (TCAP), conducted from June 2012 through June 2013, was a unique study utilizing both in situ and remotely sensed measurements designed to provide a comprehensive data set that can be used to investigate science questions related to aerosol radiative forcing and the vertical distribution of aerosol. The study sampled the atmosphere at a number of altitudes within two atmospheric columns; one located near the coast of North America (over Cape Cod, MA) and a second over the Atlantic Ocean several hundred kilometers from the coast. TCAP included the yearlong deployment of the U.S. Department of Energy's Atmospheric Radiation Measurement (ARM) Mobile Facility (AMF) located at the base of the Cape Cod column, as well as summer and winter aircraft intensive observation periods (IOPs) using the ARM Aerial Facility. One important finding from the TCAP summer IOP is the relatively common occurrence (during four of the six nearly cloud-free flights) of elevated aerosol layers in both the Cape Cod and maritime columns that were detected using the nadir pointing second-generation NASA Langley Research Center High-Spectral Resolution Lidar (HSRL-2). These elevated layers contributed up to 60% of the total observed aerosol optical depth (AOD). Many of these layers were also intercepted by the aircraft configured for in situ sampling, and the aerosol in the layers was found to have increased amounts of biomass burning material and nitrate compared to aerosol found near the surface. Both the in situ and remote sensing observations have been compared to

  13. CALIPSO and MODIS Observations of Increases in Aerosol Optical Depths near Marine Stratocumulus

    NASA Astrophysics Data System (ADS)

    Coakley, J. A.; Tahnk, W. R.

    2009-12-01

    Aerosols not only affect droplet sizes and number concentrations in marine stratocumulus but in turn the near cloud environment gives rise to changes in the aerosol particle concentrations and sizes. In addition, the clouds serve as reflectors that illuminate the adjacent cloud-free air. This extra illumination leads to overestimates of aerosol optical depths and fine mode fractions retrieved from multispectral satellite imagery. Large cloud-free ocean regions bounded on both ends, or if sufficiently large (>100 km), on at least one end by layers of marine stratocumulus, as deduced from CALIPSO lidar returns, were examined to deduce the effects of the clouds on the properties of nearby aerosols. CALIPSO aerosol optical depths composited for more than a year and covering the global oceans, 60°S-60°N, reveal that the fractional increase in aerosol optical depth in going from a cloud-free 5-km region more than 10 to 15 km from a cloud boundary to one adjacent the clouds is 10%-15% at both 532 and 1064 nm for both daytime and nighttime observations. All of the changes are statistically significant at the 90% confidence level or greater. The associated reduction in the 532/1064 Ånsgtröm Exponent is 0.023 for the nighttime observations, but owing to a poorer signal to noise ratio, no change in the Exponent is detected for the daytime observations. For comparison, the MODIS aerosol optical depths collocated with the daytime CALIPSO optical depths suggest that the fractional increases in aerosol optical depths in going from a cloud-free 10-km region 15 km from a cloud boundary to one adjacent the clouds is about 5% at both 550 and 850 nm. The associated reduction in the 550/850 Ånsgtröm Exponent is 0.053. The changes in aerosol properties die away within 10 to 20 km from the marine stratocumulus. The increases in aerosol scattering and reductions in Ånsgtröm Exponent suggest that near the clouds, the aerosol particles become larger. The fine mode fraction found in

  14. Evaluation of simulated aerosol properties with the aerosol-climate model ECHAM5-HAM using observations from the IMPACT field campaign

    NASA Astrophysics Data System (ADS)

    Roelofs, G.-J.; ten Brink, H.; Kiendler-Scharr, A.; de Leeuw, G.; Mensah, A.; Minikin, A.; Otjes, R.

    2010-08-01

    In May 2008, the measurement campaign IMPACT for observation of atmospheric aerosol and cloud properties was conducted in Cabauw, The Netherlands. With a nudged version of the coupled aerosol-climate model ECHAM5-HAM we simulate the size distribution and chemical composition of the aerosol and the associated aerosol optical thickness (AOT) for the campaign period. Synoptic scale meteorology is represented realistically through nudging of the vorticity, the divergence, the temperature and the surface pressure. Simulated concentrations of aerosol sulfate and organics at the surface are generally within a factor of two from observed values. The monthly averaged AOT from the model is 0.33, about 20% larger than observed. For selected periods of the month with relatively dry and moist conditions discrepancies are approximately -30% and +15%, respectively. Discrepancies during the dry period are partly caused by inaccurate representation of boundary layer (BL) dynamics by the model affecting the simulated AOT. The model simulates too strong exchange between the BL and the free troposphere, resulting in weaker concentration gradients at the BL top than observed for aerosol and humidity, while upward mixing from the surface layers into the BL appears to be underestimated. The results indicate that beside aerosol sulfate and organics also aerosol ammonium and nitrate significantly contribute to aerosol water uptake. The simulated day-to-day variability of AOT follows synoptic scale advection of humidity rather than particle concentration. Even for relatively dry conditions AOT appears to be strongly influenced by the diurnal cycle of RH in the lower boundary layer, further enhanced by uptake and release of nitric acid and ammonia by aerosol water.

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  16. Influence of particle-phase state on the hygroscopic behavior of mixed organic-inorganic aerosols

    NASA Astrophysics Data System (ADS)

    Hodas, N.; Zuend, A.; Mui, W.; Flagan, R. C.; Seinfeld, J. H.

    2015-05-01

    Recent work has demonstrated that organic and mixed organic-inorganic particles can exhibit multiple phase states depending on their chemical composition and on ambient conditions such as relative humidity (RH). To explore the extent to which water uptake varies with particle-phase behavior, hygroscopic growth factors (HGFs) of nine laboratory-generated, organic and organic-inorganic aerosol systems with physical states ranging from well-mixed liquids to phase-separated particles to viscous liquids or semi-solids were measured with the Differential Aerosol Sizing and Hygroscopicity Spectrometer Probe at RH values ranging from 40 to 90%. Water-uptake measurements were accompanied by HGF and RH-dependent thermodynamic equilibrium calculations using the Aerosol Inorganic-Organic Mixtures Functional groups Activity Coefficients (AIOMFAC) model. In addition, AIOMFAC-predicted growth curves are compared to several simplified HGF modeling approaches: (1) representing particles as ideal, well-mixed liquids; (2) forcing a single phase but accounting for non-ideal interactions through activity coefficient calculations; and (3) a Zdanovskii-Stokes-Robinson-like calculation in which complete separation of the inorganic and organic components is assumed at all RH values, with water uptake treated separately in each of the individual phases. We observed variability in the characteristics of measured hygroscopic growth curves across aerosol systems with differing phase behaviors, with growth curves approaching smoother, more continuous water uptake with decreasing prevalence of liquid-liquid phase separation and increasing oxygen : carbon ratios of the organic aerosol components. We also observed indirect evidence for the dehydration-induced formation of highly viscous semi-solid phases and for kinetic limitations to the crystallization of ammonium sulfate at low RH for sucrose-containing particles. AIOMFAC-predicted growth curves are generally in good agreement with the HGF

  17. Influence of particle phase state on the hygroscopic behavior of mixed organic-inorganic aerosols

    NASA Astrophysics Data System (ADS)

    Hodas, N.; Zuend, A.; Mui, W.; Flagan, R. C.; Seinfeld, J. H.

    2014-12-01

    Recent work has demonstrated that organic and mixed organic-inorganic particles can exhibit multiple phase states depending on their chemical composition and on ambient conditions such as relative humidity (RH). To explore the extent to which water uptake varies with particle phase behavior, hygroscopic growth factors (HGFs) of nine laboratory-generated, organic and organic-inorganic aerosol systems with physical states ranging from well-mixed liquids, to phase-separated particles, to viscous liquids or semi-solids were measured with the Differential Aerosol Sizing and Hygroscopicity Spectrometer Probe at RH values ranging from 40-90%. Water-uptake measurements were accompanied by HGF and RH-dependent thermodynamic equilibrium calculations using the Aerosol Inorganic-Organic Mixtures Functional groups Activity Coefficients (AIOMFAC) model. In addition, AIOMFAC-predicted growth curves are compared to several simplified HGF modeling approaches: (1) representing particles as ideal, well-mixed liquids, (2) forcing a single phase, but accounting for non-ideal interactions through activity coefficient calculations, and (3) a Zdanovskii-Stokes-Robinson-like calculation in which complete separation between the inorganic and organic components is assumed at all RH values, with water-uptake treated separately in each of the individual phases. We observed variability in the characteristics of measured hygroscopic growth curves across aerosol systems with differing phase behaviors, with growth curves approaching smoother, more continuous water uptake with decreasing prevalence of liquid-liquid phase separation and increasing oxygen : carbon ratios of the organic aerosol components. We also observed indirect evidence for the dehydration-induced formation of highly viscous semi-solid phases and for kinetic limitations to the crystallization of ammonium sulfate at low RH for sucrose-containing particles. AIOMFAC-predicted growth curves are generally in good agreement with the HGF

  18. Measurements of the chemical, physical, and optical properties of single aerosol particles

    NASA Astrophysics Data System (ADS)

    Moffet, Ryan Christopher

    Knowledge of aerosol physical, chemical, optical properties is essential for judging the effect that particulates have on human health, climate and visibility. The aerosol time-of-flight mass spectrometer (ATOFMS) is capable of measuring, in real-time, the size and chemical composition of atmospheric aerosols. This was exemplified by the recent deployments of the ATOFMS to Mexico City and Riverside. The ATOFMS provided rapid information about the major particle types present in the atmosphere. Industrial sources of particles, such as fine mode particles containing lead, zinc and chloride were detected in Mexico City. The rapid time response of the ATOFMS was also exploited to characterize a coarse particle concentrator used in human health effects studies. The ATOFMS showed the ability to detect changes in particle composition with a time resolution of 15 min during short 2 hour human exposure studies. As a major component of this work, an optical measurement has been added to the ATOFMS. The scattered light intensity was acquired for each sized and chemically analyzed particle. This scattering information together with the particle aerodynamic diameter, enabled the refractive index and density of the aerosol to be retrieved. This method was validated in the laboratory using different test particles such as oils, aqueous salt solutions and black carbon particles. It was found that the nozzle-type inlet does not evaporate aqueous salt particles as has been observed for aerodynamic lens inlets. These new optical and microphysical measurements were integrated into the ATOFMS for field deployment in Riverside and Mexico City. For both cities, the different mixing states were found to have unique refractive indexes and densities. A fraction of the strongly absorbing elemental carbon particles were observed to have a spherical morphology due to heavy mixing with secondary species. In addition to the quantitative refractive index and effective density measurements

  19. Atmospheric Condensational Properties of Ultrafine Chain and Fractal Aerosol Particles

    NASA Technical Reports Server (NTRS)

    Marlow, William H.

    1997-01-01

    The purpose for the research sponsored by this grant was to lay the foundations for qualitative understanding and quantitative description of the equilibrium vapor pressure of water vapor over the irregularly shaped, carbonaceous particles that are present in the atmosphere. This work apparently was the first systematic treatment of the subject. Research was conducted in two complementary components: 1. Calculations were performed of the equilibrium vapor pressure of water over particles comprised of aggregates of spheres in the 50-200 nm radius range. The purposes of this work were two-fold. First, since no systematic treatment of this subject had previously been conducted, its availability would be directly useful for quantitative treatment for a limited range of atmospheric aerosols. Second, it would provide qualitative indications of the effects of highly irregular particle shape on equilibrium vapor pressure of aggregates comprised of smaller spheres.

  20. Rocket-borne probes for charged ionospheric aerosol particles

    NASA Astrophysics Data System (ADS)

    Smiley, B.; Sternovsky, Z.; Robertson, S.; Horanyi, M.

    2003-10-01

    A series of rocket-borne probes is described for detecting charged solid particles in the ionosphere. The probes are flat charge-collecting surfaces on the skin of the rocket that have behind them a permanent magnet that magnetically insulates the probe from electrons. Several probes have also had a small positive bias of several volts to reduce collection of light molecular ions. The current that is recorded is thus from heavier charged particles and this is converted to a charge number density. Several summer launches into the polar mesosphere have found charged aerosol layers at the altitudes of noctilucent clouds and polar summer mesospheric radar echoes. A new probe is being developed in which electric deflection is used to determine the mass of the particles. This probe takes advantage of the reduced density behind the shock front to increase the mean free path within the instrument, so that cryopumping is not required.

  1. Linking variations in sea spray aerosol particle hygroscopicity to composition during two microcosm experiments

    NASA Astrophysics Data System (ADS)

    Forestieri, Sara D.; Cornwell, Gavin C.; Helgestad, Taylor M.; Moore, Kathryn A.; Lee, Christopher; Novak, Gordon A.; Sultana, Camille M.; Wang, Xiaofei; Bertram, Timothy H.; Prather, Kimberly A.; Cappa, Christopher D.

    2016-07-01

    The extent to which water uptake influences the light scattering ability of marine sea spray aerosol (SSA) particles depends critically on SSA chemical composition. The organic fraction of SSA can increase during phytoplankton blooms, decreasing the salt content and therefore the hygroscopicity of the particles. In this study, subsaturated hygroscopic growth factors at 85 % relative humidity (GF(85 %)) of predominately submicron SSA particles were quantified during two induced phytoplankton blooms in marine aerosol reference tanks (MARTs). One MART was illuminated with fluorescent lights and the other was illuminated with sunlight, referred to as the "indoor" and "outdoor" MARTs, respectively. Optically weighted GF(85 %) values for SSA particles were derived from measurements of light scattering and particle size distributions. The mean optically weighted SSA diameters were 530 and 570 nm for the indoor and outdoor MARTs, respectively. The GF(85 %) measurements were made concurrently with online particle composition measurements, including bulk composition (using an Aerodyne high-resolution aerosol mass spectrometer) and single particle (using an aerosol time-of-flight mass spectrometer) measurement, and a variety of water-composition measurements. During both microcosm experiments, the observed optically weighted GF(85 %) values were depressed substantially relative to pure inorganic sea salt by 5 to 15 %. There was also a time lag between GF(85 %) depression and the peak chlorophyll a (Chl a) concentrations by either 1 (indoor MART) or 3-to-6 (outdoor MART) days. The fraction of organic matter in the SSA particles generally increased after the Chl a peaked, also with a time lag, and ranged from about 0.25 to 0.5 by volume. The observed depression in the GF(85 %) values (relative to pure sea salt) is consistent with the large observed volume fractions of non-refractory organic matter (NR-OM) comprising the SSA. The GF(85 %) values exhibited a reasonable negative

  2. A New Electrospray Aerosol Generator with High Particle Transmission Efficiency

    PubMed Central

    Fu, Huijing; Patel, Anand C.; Holtzman, Michael J.; Chen, Da-Ren

    2012-01-01

    A new single-capillary electrospray (ES) aerosol generator has been developed for monodisperse particle production with maximal transmission efficiency. The new generator consists of both a spray chamber in a point-to-orifice-plate configuration and a charge reduction chamber that can hold up to 4 Nuclespot ionizers (Model P-2042, NRD Inc.). The 2 chambers are partitioned by an orifice plate. To optimize the particle transmission efficiency of the prototype, a systematic study was performed on the generator by varying the system setup and operation. Two key dimensions of the generator setup, the orifice diameter and the distance from the capillary tip to the orifice plate, were varied. Fluorescence analysis was applied to characterize the loss of ES-generated particles at different locations of the prototype. It was found that particle loss in the generator could be reduced by either increasing the orifice diameter or decreasing the distance between the capillary tip and the orifice plate. Increasing either the total radioactivity of the ionizers or the flowrate of the particle carrier gas also further decreased the particle loss in the system. The maximum particle transmission efficiency of 88.0% was obtained with the spray chamber fully opened to the charge reduction chamber, the capillary tip at the same level as the orifice plate, and 4 bipolar ionizers installed. PMID:22829715

  3. Method and apparatus for aerosol particle absorption spectroscopy

    DOEpatents

    Campillo, Anthony J.; Lin, Horn-Bond

    1983-11-15

    A method and apparatus for determining the absorption spectra, and other properties, of aerosol particles. A heating beam source provides a beam of electromagnetic energy which is scanned through the region of the spectrum which is of interest. Particles exposed to the heating beam which have absorption bands within the band width of the heating beam absorb energy from the beam. The particles are also illuminated by light of a wave length such that the light is scattered by the particles. The absorption spectra of the particles can thus be determined from an analysis of the scattered light since the absorption of energy by the particles will affect the way the light is scattered. Preferably the heating beam is modulated to simplify the analysis of the scattered light. In one embodiment the heating beam is intensity modulated so that the scattered light will also be intensity modulated when the particles absorb energy. In another embodiment the heating beam passes through an interferometer and the scattered light reflects the Fourier Transform of the absorption spectra.

  4. A New Electrospray Aerosol Generator with High Particle Transmission Efficiency.

    PubMed

    Fu, Huijing; Patel, Anand C; Holtzman, Michael J; Chen, Da-Ren

    2011-01-01

    A new single-capillary electrospray (ES) aerosol generator has been developed for monodisperse particle production with maximal transmission efficiency. The new generator consists of both a spray chamber in a point-to-orifice-plate configuration and a charge reduction chamber that can hold up to 4 Nuclespot ionizers (Model P-2042, NRD Inc.). The 2 chambers are partitioned by an orifice plate. To optimize the particle transmission efficiency of the prototype, a systematic study was performed on the generator by varying the system setup and operation. Two key dimensions of the generator setup, the orifice diameter and the distance from the capillary tip to the orifice plate, were varied. Fluorescence analysis was applied to characterize the loss of ES-generated particles at different locations of the prototype. It was found that particle loss in the generator could be reduced by either increasing the orifice diameter or decreasing the distance between the capillary tip and the orifice plate. Increasing either the total radioactivity of the ionizers or the flowrate of the particle carrier gas also further decreased the particle loss in the system. The maximum particle transmission efficiency of 88.0% was obtained with the spray chamber fully opened to the charge reduction chamber, the capillary tip at the same level as the orifice plate, and 4 bipolar ionizers installed. PMID:22829715

  5. Aerosol indirect effect on warm clouds over South-East Atlantic, from co-located MODIS and CALIPSO observations

    NASA Astrophysics Data System (ADS)

    Costantino, L.; Bréon, F.-M.

    2013-01-01

    In this study, we provide a comprehensive analysis of aerosol interaction with warm boundary layer clouds over the South-East Atlantic. We use aerosol and cloud parameters derived from MODIS observations, together with co-located CALIPSO estimates of the layer altitudes, to derive statistical relationships between aerosol concentration and cloud properties. The CALIPSO products are used to differentiate between cases of mixed cloud-aerosol layers from cases where the aerosol is located well-above the cloud top. This technique allows us to obtain more reliable estimates of the aerosol indirect effect than from simple relationships based on vertically integrated measurements of aerosol and cloud properties. Indeed, it permits us to somewhat distinguish the effects of aerosol and meteorology on the clouds, although it is not possible to fully ascertain the relative contribution of each on the derived statistics. Consistently with the results from previous studies, our statistics clearly show that aerosol affects cloud microphysics, decreasing the Cloud Droplet Radius (CDR). The same data indicate a concomitant strong decrease in cloud Liquid Water Path (LWP), which is inconsistent with the hypothesis of aerosol inhibition of precipitation (Albrecht, 1989). We hypothesise that the observed reduction in LWP is the consequence of dry air entrainment at cloud top. The combined effect of CDR decrease and LWP decrease leads to rather small sensitivity of the Cloud Optical Thickness (COT) to an increase in aerosol concentration. The analysis of MODIS-CALIPSO coincidences also evidences an aerosol enhancement of low cloud cover. Surprisingly, the Cloud Fraction (CLF) response to aerosol invigoration is much stronger when (absorbing) particles are located above cloud top than in cases of physical interaction. This result suggests a relevant aerosol radiative effect on low cloud occurrence: absorbing particles above the cloud top may heat the corresponding atmosphere layer

  6. Aerosol indirect effect on warm clouds over South-East Atlantic, from co-located MODIS and CALIPSO observations

    NASA Astrophysics Data System (ADS)

    Costantino, Lorenzo; Bréon, François-Marie

    2013-04-01

    In this study, we provide a comprehensive analysis of aerosol interaction with warm boundary layer clouds over the South-East Atlantic. We use aerosol and cloud parameters derived from MODIS observations, together with co-located CALIPSO estimates of the layer altitudes, to derive statistical relationships between aerosol concentration and cloud properties. The CALIPSO products are used to differentiate between cases of mixed cloud-aerosol layers from cases where the aerosol is located well-above the cloud top. This technique allows us to obtain more reliable estimates of the aerosol indirect effect than from simple relationships based on vertically integrated measurements of aerosol and cloud properties. Indeed, it permits us to somewhat distinguish the effects of aerosol and meteorology on the clouds, although it is not possible to fully ascertain the relative contribution of each on the derived statistics. Consistently with the results from previous studies, our statistics clearly show that aerosol affects cloud microphysics, decreasing the Cloud Droplet Radius (CDR). The same data indicate a concomitant strong decrease in cloud Liquid Water Path (LWP), which is inconsistent with the hypothesis of aerosol inhibition of precipitation (Albrecht, 1989). We hypothesise that the observed reduction in LWP is the consequence of dry air entrainment at cloud top. The combined effect of CDR decrease and LWP decrease leads to rather small sensitivity of the Cloud Optical Thickness (COT) to an increase in aerosol concentration. The analysis of MODIS-CALIPSO coincidences also evidences an aerosol enhancement of low cloud cover. Surprisingly, the Cloud Fraction (CLF) response to aerosol invigoration is much stronger when (absorbing) particles are located above cloud top than in cases of physical interaction. This result suggests a relevant aerosol radiative effect on low cloud occurrence: absorbing particles above the cloud top may heat the corresponding atmosphere layer

  7. Distribution of Aerosols in the Arctic as Observed by CALIOP

    NASA Astrophysics Data System (ADS)

    Winker, D.; Kittaka, C.

    2007-12-01

    The Arctic climate is now recognized to be uniquely sensitive to atmospheric perturbations. Pollution aerosols and smoke from boreal fires have potentially important impacts on Arctic climate but there are many uncertainties. Aerosol in the Arctic, generally referred to as "Arctic haze", has been studied with great interest for over thirty years. Much has been learned about the composition and sources of the haze yet our knowledge is largely based on long term measurements at a very few widely dispersed sites, augmented by modeling activities and occasional field campaigns. Transport pathways from source regions into the Arctic are not well understood. Emission patterns have changed over the last several decades, but the impact of this on concentrations and distribution of Arctic haze are understood only in the crudest sense. Due to poor lighting conditions, extended periods of darkness, and surfaces covered by snow and ice, satellite sensors have been unable to provide much information on Arctic haze to date. The CALIPSO satellite carries CALIOP, a two-wavelength polarization lidar, optimized for profiling clouds and aerosols. CALIOP has been acquiring global observations since June 2006 and provides our first opportunity to observe the distribution and seasonal variation of aerosol in the Arctic. The Arctic is characterized by the prevalence of optically thin ice clouds and clouds composed of supercooled water, often occurring in the same atmospheric column along with aerosol. CALIOP depolarization signals are used to discriminate Arctic haze from optically thin cirrus and diamond dust. Two-wavelength returns aid in the discrimination of aerosol and optically thin water cloud. Results of initial analyses of CALIOP aerosol observations in the Arctic will be presented. This work is a preliminary analysis in support of the NASA Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS) field campaign planned for April 2008.

  8. Generation and characterization of large-particle aerosols using a center flow tangential aerosol generator with a nonhuman-primate, head-only aerosol chamber

    PubMed Central

    Bohannon, J. Kyle; Lackemeyer, Matthew G.; Kuhn, Jens H.; Wada, Jiro; Bollinger, Laura; Jahrling, Peter B.; Johnson, Reed F.

    2016-01-01

    Aerosol droplets or particles produced from infected respiratory secretions have the potential to infect another host through inhalation. These respiratory particles can be polydisperse and range from 0.05–500 μm in diameter. Animal models of infection are generally established to facilitate the potential licensure of candidate prophylactics and/or therapeutics. Consequently, aerosol-based animal infection models are needed to properly study and counter airborne infections. Ideally, experimental aerosol exposure should reliably result in animal disease that faithfully reproduces the modelled human disease. Few studies have been performed to explore the relationship between exposure particle size and induced disease course for infectious aerosol particles. The center flow tangential aerosol generator (CenTAG™) produces large-particle aerosols capable of safely delivering a variety of infectious aerosols to nonhuman primates within a Class III Biological Safety Cabinet (BSC) for establishment or refinement of nonhuman primate infectious disease models. Here we report the adaptation of this technology to the Animal Biosafety Level 4 (ABSL-4) environment for the future study of high-consequence viral pathogens and the characterization of CenTAG™-created sham (no animal, no virus) aerosols using a variety of viral growth media and media supplements. PMID:25970823

  9. Generation and characterization of large-particle aerosols using a center flow tangential aerosol generator with a non-human-primate, head-only aerosol chamber.

    PubMed

    Bohannon, J Kyle; Lackemeyer, Matthew G; Kuhn, Jens H; Wada, Jiro; Bollinger, Laura; Jahrling, Peter B; Johnson, Reed F

    2015-01-01

    Aerosol droplets or particles produced from infected respiratory secretions have the potential to infect another host through inhalation. These respiratory particles can be polydisperse and range from 0.05 to 500 µm in diameter. Animal models of infection are generally established to facilitate the potential licensure of candidate prophylactics and/or therapeutics. Consequently, aerosol-based animal infection models are needed to properly study and counter airborne infections. Ideally, experimental aerosol exposure should reliably result in animal disease that faithfully reproduces the modeled human disease. Few studies have been performed to explore the relationship between exposure particle size and induced disease course for infectious aerosol particles. The center flow tangential aerosol generator (CenTAG™) produces large-particle aerosols capable of safely delivering a variety of infectious aerosols to non-human primates (NHPs) within a Class III Biological Safety Cabinet (BSC) for establishment or refinement of NHP infectious disease models. Here, we report the adaptation of this technology to the Animal Biosafety Level 4 (ABSL-4) environment for the future study of high-consequence viral pathogens and the characterization of CenTAG™-created sham (no animal, no virus) aerosols using a variety of viral growth media and media supplements. PMID:25970823

  10. Non-Spherical Aerosol Phase Functions Derived from MODIS and AERONET Observations

    NASA Technical Reports Server (NTRS)

    Remer, L. A.; Kaufman, Y. J.; Levy, R. C.; Dubovik, O.; Lau, William K. M. (Technical Monitor)

    2002-01-01

    We compare MODIS (Moderate Resolution Imaging Spectroradiometer) satellite aerosol retrievals of spectral optical thickness and size parameters over ocean with the same quantities derived from AERONET (Aerosol Robotic Network) observations made at island and coastal sites. Over much of the globe, the satellite-derived quantities agree well with the AERONET quantities. However, in regimes dominated by desert dust aerosol, the agreement is less robust. In the dust regimes, the MODIS retrievals show greater spectral dependence and report smaller particle sizes than do the AERONET derivations. We suggest that the reason for this discrepancy is the nonspherical nature of desert dust particles, which the initial MODIS algorithm is not able to handle. Using the discrepancy between MODIS and AERONET derived spectral optical thickness as an asset, instead of a detriment, we reconstruct the aerosol phase functions that the MODIS algorithm would have needed in order to match the AERONET retrievals. No assumptions of particle shape are used in the derivation of these functions and the results are empirical total column, ambient phase functions. We compare the empirically derived phase functions with phase functions calculated from spheres and spheroids, both situations in which assumptions about particle shape must be made. The resulting empirical nonspherical phase functions will be included in future updates of the MODIS algorithm.

  11. 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

  12. Gas uptake and chemical aging of semisolid organic aerosol particles

    PubMed Central

    Shiraiwa, Manabu; Ammann, Markus; Koop, Thomas; Pöschl, Ulrich

    2011-01-01

    Organic substances can adopt an amorphous solid or semisolid state, influencing the rate of heterogeneous reactions and multiphase processes in atmospheric aerosols. Here we demonstrate how molecular diffusion in the condensed phase affects the gas uptake and chemical transformation of semisolid organic particles. Flow tube experiments show that the ozone uptake and oxidative aging of amorphous protein is kinetically limited by bulk diffusion. The reactive gas uptake exhibits a pronounced increase with relative humidity, which can be explained by a decrease of viscosity and increase of diffusivity due to hygroscopic water uptake transforming the amorphous organic matrix from a glassy to a semisolid state (moisture-induced phase transition). The reaction rate depends on the condensed phase diffusion coefficients of both the oxidant and the organic reactant molecules, which can be described by a kinetic multilayer flux model but not by the traditional resistor model approach of multiphase chemistry. The chemical lifetime of reactive compounds in atmospheric particles can increase from seconds to days as the rate of diffusion in semisolid phases can decrease by multiple orders of magnitude in response to low temperature or low relative humidity. The findings demonstrate that the occurrence and properties of amorphous semisolid phases challenge traditional views and require advanced formalisms for the description of organic particle formation and transformation in atmospheric models of aerosol effects on air quality, public health, and climate. PMID:21690350

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

    NASA Astrophysics Data System (ADS)

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

    2003-02-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  15. Aerosol Measurements in the Atmospheric Surface Layer at L'Aquila, Italy: Focus on Biogenic Primary Particles

    NASA Astrophysics Data System (ADS)

    Pitari, Giovanni; Coppari, Eleonora; De Luca, Natalia; Di Carlo, Piero; Pace, Loretta

    2014-09-01

    Two year measurements of aerosol concentration and size distribution (0.25 μm < d < 30 μm) in the atmospheric surface layer, collected in L'Aquila (Italy) with an optical particle counter, are reported and analysed for the different modes of the particle size distribution. A different seasonal behaviour is shown for fine mode aerosols (largely produced by anthropogenic combustion), coarse mode and large-sized aerosols, whose abundance is regulated not only by anthropogenic local production, but also by remote natural sources (via large scale atmospheric transport) and by local sources of primary biogenic aerosols. The observed total abundance of large particles with diameter larger than 10 μm is compared with a statistical counting of primary biogenic particles, made with an independent technique. Results of these two observational approaches are analysed and compared to each other, with the help of a box model driven by observed meteorological parameters and validated with measurements of fine and coarse mode aerosols and of an atmospheric primary pollutant of anthropogenic origin (NOx). Except in winter months, primary biogenic particles in the L'Aquila measurement site are shown to dominate the atmospheric boundary layer population of large aerosol particles with diameter larger than 10 μm (about 80 % of the total during summer months), with a pronounced seasonal cycle, contrary to fine mode aerosols of anthropogenic origin. In order to explain these findings, the main mechanisms controlling the abundance and variability of particulate matter tracers in the atmospheric surface layer are analysed with the numerical box-model.

  16. Satellite observation of aerosol - cloud interactions over semi-arid and arid land regions

    NASA Astrophysics Data System (ADS)

    Klüser, L.; Holzer-Popp, T.

    2012-04-01

    optical depth and ice water path points towards an invigoration of cirrus clouds, which is also supported by the very high fraction of low ice cloud optical depth observations in the Sahel. Ice cloud cover is increased by up to 25% for almost all observations, the impact is stronger for mineral dust than for fine mode aerosol. The ice cloud fraction as ratio between ice cloud cover and total cloud cover is also increased for all regions and aerosol regimes. Also here the strongest impact is observed for mineral dust, reflecting the good suitability of dust particles as ice nuclei. The effects seen by the three satellite datasets are overall consistent. The analysis clearly shows that for ice clouds the Twomey effect also can be observed as for liquid water clouds, but that also other effects impact on optical depth variation. Ice water path is generally increased by aerosol, but in the Sahel also a decrease is observed which can be attributed to a higher cirrus fraction at low CTT.

  17. Observations of relative humidity effects on aerosol light scattering in the Yangtze River Delta of China

    NASA Astrophysics Data System (ADS)

    Zhang, L.; Sun, J. Y.; Shen, X. J.; Zhang, Y. M.; Che, H. C.; Ma, Q. L.; Zhang, Y. W.; Zhang, X. Y.; Ogren, J. A.

    2015-01-01

    Scattering of solar radiation by aerosol particles is highly dependent on relative humidity (RH) as hygroscopic particles take up water with increasing RH. To achieve a better understanding of the effect of aerosol hygroscopic growth on light scattering properties and radiative forcing, a field campaign was carried out in the Yangtze River Delta of China in March 2013. During the observation period, the mean and standard deviation of enhancement factors at RH=85% for the scattering coefficient (f(85%)), backscattering coefficient (fb(85%)) and hemispheric backscatter fraction (fβ(85%)) were 1.58 ± 0.12, 1.25 ± 0.07 and 0.79 ± 0.04, respectively, i.e. aerosol scattering coefficient and backscattering coefficient increased by 58 and 25% as the RH increased from 40 to 85%. Meanwhile, the aerosol hemispheric backscatter fraction decreased by 21%. The relative amount of organic matter (OM) and inorganics in PM1 was found to be a main factor determining the magnitude of f(RH), the highest values of f(RH) corresponded to the aerosols with a small fraction of organic matter (OM), and vice versa. The relative amount of NO3- in fine particles was strongly correlated to f(85%), which suggests NO3- played a vital role in aerosol hygroscopic growth during this study. The mass percentage of nitrate also had a close relation to the curvature of humidograms, namely, the higher the nitrate concentration is, the straighter the humidogram will be. Air masses that arrived at LinAn in March can be classified into northerly-polluted, locally-polluted and dust-influenced types, the scattering enhancement factors at 85% RH were 1.52 ± 0.10, 1.64 ± 0.09 and 1.48 ± 0.05, respectively. The sensitivity of the aerosol radiative forcing to f(RH) at the measured mean ambient RH 67% for various aerosol types was also estimated. The direct radiative forcing increased by 11.8, 19.5, and 10.5%, respectively, for locally-polluted, northerly-polluted and dust-influenced aerosols due to aerosol

  18. 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.

  19. Self-assembly of marine exudate particles and their impact on the CCN properties of nascent marine aerosol

    NASA Astrophysics Data System (ADS)

    Schill, S.; Zimmermann, K.; Ryder, O. S.; Campbell, N.; Collins, D. B.; Gianneschi, N.; Bertram, T. H.

    2013-12-01

    Spontaneous self-assembly of marine exudate particles has previously been observed in filtered seawater samples. The chemicophysical properties of these particles may alter the chemical composition and CCN properties of nascent marine aerosol, yet to date simultaneous measurement of seawater exudate particle formation rates and number distributions, with aerosol particle formation rates and CCN activity are lacking. Here, we use a novel Marine Aerosol Reference Tank (MART) system to experimentally mimic a phytoplankton bloom via sequential addition of biological surrogates, including sterol, galactose, lipopolysaccharide, BSA protein, and dipalmitoylphosphatidylcholine. Nascent sea-spray aerosol are generated in the MART system via a continuous plunging waterfall. Exudate particle assembly in the water is monitored via dynamic light scattering (DLS) and transmission electron microscopy (TEM) to obtain both the assembly kinetics of the particles as well as particle number distributions Simultaneous characterization of both particle production rates and super-saturated particle hygroscopicity are also discussed. This study permits analysis of the controlling role of the molecular composition of dissolved organic carbon in setting the production rates of colloidal material in the surface oceans.

  20. Microscopic Characterization of Carbonaceous Aerosol Particle Aging in the Outflow from Mexico City

    SciTech Connect

    Moffet, R. C.; Henn, T. R.; Tivanski, A. V.; Hopkins, R. J.; Desyaterik, Y.; Kilcoyne, A. L. D.; Tyliszczak, T.; Fast, J.; Barnard, J.; Shutthanandan, V.; Cliff, S.S.; Perry, K. D.; Laskin, A.; Gilles, M. K.

    2009-09-16

    This study was part of the Megacities Initiative: Local and Global Research Observations (MILAGRO) field campaign conducted in Mexico City Metropolitan Area during spring 2006. The physical and chemical transformations of particles aged in the outflow from Mexico City were investigated for the transport event of 22 March 2006. A detailed chemical analysis of individual particles was performed using a combination of complementary microscopy and micro-spectroscopy techniques. The applied techniques included scanning transmission X-ray microscopy (STXM) coupled with near edge X-ray absorption fine structure spectroscopy (NEXAFS) and computer controlled scanning electron microscopy with an energy dispersive X-ray analyzer (CCSEM/EDX). As the aerosol plume evolves from the city center, the organic mass per particle increases and the fraction of carbon-carbon double bonds (associated with elemental carbon) decreases. Organic functional groups enhanced with particle age include: carboxylic acids, alkyl groups, and oxygen bonded alkyl groups. At the city center (T0) the most prevalent aerosol type contained inorganic species (composed of sulfur, nitrogen, oxygen, and potassium) coated with organic material. At the T1 and T2 sites, located northeast of T0 (~;;29 km and ~;;65 km, respectively), the fraction of homogenously mixed organic particles increased in both size and number. These observations illustrate the evolution of the physical mixing state and organic bonding in individual particles in a photochemically active environment.

  1. Assessment of aerosol's mass concentrations from measured linear particle depolarization ratio (vertically resolved) and simulations

    NASA Astrophysics Data System (ADS)

    Nemuc, A.; Vasilescu, J.; Talianu, C.; Belegante, L.; Nicolae, D.

    2013-11-01

    Multi-wavelength depolarization Raman lidar measurements from Magurele, Romania are used in this study along with simulated mass-extinction efficiencies to calculate the mass concentration profiles of different atmospheric components, due to their different depolarization contribution to the 532 nm backscatter coefficient. Linear particle depolarization ratio (δpart) was computed using the relative amplification factor and the system-dependent molecular depolarization. The low depolarizing component was considered as urban/smoke, with a mean δpart of 3%, while for the high depolarizing component (mineral dust) a mean δpart of 35% was assumed. For this study 11 months of lidar measurements were analysed. Two study cases are presented in details: one for a typical Saharan dust aerosol intrusion, 10 June 2012 and one for 12 July 2012 when a lofted layer consisting of biomass burning smoke extended from 3 to 4.5 km height. Optical Properties of Aerosols and Clouds software package (OPAC) classification and conversion factors were used to calculate mass concentrations. We found that calibrated depolarization measurements are critical in distinguishing between smoke-reach aerosol during the winter and dust-reach aerosol during the summer, as well as between elevated aerosol layers having different origins. Good agreement was found between lidar retrievals and DREAM- Dust REgional Atmospheric Model forecasts in cases of Saharan dust. Our method was also compared against LIRIC (The Lidar/Radiometer Inversion Code) and very small differences were observed.

  2. Assessment of aerosol's mass concentrations from measured linear particle depolarization ratio (vertically resolved) and simulations

    NASA Astrophysics Data System (ADS)

    Nemuc, A.; Vasilescu, J.; Talianu, C.; Belegante, L.; Nicolae, D.

    2013-06-01

    Multiwavelength depolarization Raman lidar measurements from Magurele, Romania are used in this study along with simulated mass-extinction efficiencies to calculate the mass concentrations profiles of different atmospheric components, due to their different depolarization contribution to the 532 nm backscatter coefficient. Linear particle depolarization ratio (δpart) was computed using the relative amplification factor and the system-dependent molecular depolarization. The low depolarizing component was considered as urban/smoke, with a mean δpart of 3%, while for the high depolarizing component (mineral dust) a mean δpart of 35% was assumed. For this study 11 months of lidar measurements were analyzed. Two study cases are presented in details: one for a typical Saharan dust aerosol intrusion, 10 June 2012 and one for 12 July 2012 when a lofted layer consisting of biomass burning smoke extended from 3 to 4.5 km height. Optical Properties of Aerosols and Clouds software package (OPAC) classification and conversion factors were used to calculate mass concentrations. We found that calibrated depolarization measurements are critical to distinguish between smoke-reach aerosol during the winter and dust-reach aerosol during the summer, as well as between elevated aerosol layers having different origins. Good agreement was found between lidar retrievals and DREAM- Dust REgional Atmospheric Model forecasts in cases of Saharan dust. Our method was also compared against LIRIC (The Lidar/Radiometer Inversion Code) and very small differences were observed.

  3. Observational constraints for climate forcing by biomass burning aerosols

    NASA Astrophysics Data System (ADS)

    Penner, J. E.; Zhou, C.; Prather, M. J.; Xu, L.

    2012-12-01

    Estimates of sources of aerosols from open biomass burning vary to a significant extent, and those for pre-industrial emissions are even more uncertain. Previously, we showed how the use of a global chemical transport model together with TOMS satellite data for aerosol index and black carbon (BC) concentrations in ice-cores can be used to constrain present-day (PD) (year 2000) and pre-industrial (PI) (year 1870) emissions. The total aerosol forcing (direct and warm cloud indirect) from these emissions was estimated to be -0.065 W m-2, although values as large as -0.21 W m-2 could not be excluded. Here, we further examine the consistency between our estimates of biomass burning sources and observations of the spectrally varying AAOD from AERONET. We present adjusted estimates that also include these observations.

  4. Organic Mass to Organic Carbon ratio in Atmospheric Aerosols: Observations and Global Simulations

    NASA Astrophysics Data System (ADS)

    Tsigaridis, K.; Kanakidou, M.; Daskalakis, N.

    2012-12-01

    Organic compounds play an important role in atmospheric chemistry and affect Earth's climate through their impact on oxidants and aerosol formation (e.g. O3 and organic aerosols (OA)). Due to the complexity of the mixture of organics in the atmosphere, the organic-mass-to-organic-carbon ratio (OM/OC) is often used to characterize the organic component in atmospheric aerosols. This ratio varies dependant on the aerosol origin and the chemical processing in the atmosphere. Atmospheric observations have shown that as OA and its precursor gases age in the atmosphere, it leads to the formation of more oxidized (O:C atomic ratio 0.6 to 0.8), less volatile and less hydrophobic compounds (particle growth factor at 95% relative humidity of 0.16 to 0.20) that have more similar properties than fresh aerosols. While reported OM:OC ratios observed over USA range between 1.29 and 1.95, indicating significant contribution of local pollution sources to the OC in that region, high O/C ratio associated with a high OM/OC ratio of 2.2 has been also observed for the summertime East Mediterranean aged aerosol. In global models, the OM/OC ratio is either calculated for specific compounds or estimated for compound groups. In the present study, we review OM/OC observations and compare them with simulations from a variety of models that contributed to the AEROCOM exercise. We evaluate the chemical processing level of atmospheric aerosols simulated by the models. A total of 32 global chemistry transport models are considered in this study with variable complexity of the representation of OM/OC ratio in the OA. The analysis provides an integrated view of the OM/OC ratio in the global atmosphere and of the accuracy of its representation in the global models. Implications for atmospheric chemistry and climate simulations are discussed.

  5. Formation and Growth of New Organic Aerosol Particles over the Deepwater Horizon Oil Spill

    NASA Astrophysics Data System (ADS)

    Brock, C. A.; Murphy, D. M.; Bahreini, R.; Middlebrook, A. M.; De Gouw, J. A.

    2011-12-01

    Aerosol size distributions were measured in June 2010 downwind of the surface oil slick produced by the Deepwater Horizon oil spill in the Gulf of Mexico. Rapid condensation of partially oxidized hydrocarbons was responsible for formation of a plume of secondary organic aerosol downwind of the spill region. New particles were nucleated upwind of the freshest surface oil but downwind of oil that surfaced less than 100 hours previously. These new particles grew by condensation at rates of ~20 nm hr-1; preexisting accumulation mode particles grew by ~10 nm hr-1. The gas-phase concentration of a condensing species necessary to support the observed growth rate assuming irreversible adsorption with unit accommodation coefficient is estimated to be ~0.04-0.09 μg m-3 (~3-8 pptv). The ratio of growth rates for newly formed particles to accumulation mode particles was consistent within error limits with irreversible condensation. Because new particle formation did not occur in areas away from the <100 hr-old oil slick, these results indicate that the oxidation products of VOC species, probably C14-C16 compounds, were directly involved in the growth of the new particles. While a unique and extreme environment, the oil spill plume provides insight into similar processes that may occur in urban and industrial areas where petrochemical products are produced and consumed.

  6. Aerosol synthesis of nano and micro-scale zero valent metal particles from oxide precursors

    SciTech Connect

    Phillips, Jonathan; Luhrs, Claudia; Lesman, Zayd; Soliman, Haytham; Zea, Hugo

    2010-01-01

    In this work a novel aerosol method, derived form the batch Reduction/Expansion Synthesis (RES) method, for production of nano / micro-scale metal particles from oxides and hydroxides is presented. In the Aerosol-RES (A-RES) method, an aerosol, consisting of a physical mixture of urea and metal oxide or hydroxides, is passed through a heated oven (1000 C) with a residence time of the order of 1 second, producing pure (zero valent) metal particles. It appears that the process is flexible regarding metal or alloy identity, allows control of particle size and can be readily scaled to very large throughput. Current work is focused on creating nanoparticles of metal and metal alloy using this method. Although this is primarily a report on observations, some key elements of the chemistry are clear. In particular, the reducing species produced by urea decomposition are the primary agents responsible for reduction of oxides and hydroxides to metal. It is also likely that the rapid expansion that takes place when solid/liquid urea decomposes to form gas species influences the final morphology of the particles.

  7. Observations of fluorescent aerosol-cloud interactions in the free troposphere at the High-Altitude Research Station Jungfraujoch

    NASA Astrophysics Data System (ADS)

    Crawford, I.; Lloyd, G.; Herrmann, E.; Hoyle, C. R.; Bower, K. N.; Connolly, P. J.; Flynn, M. J.; Kaye, P. H.; Choularton, T. W.; Gallagher, M. W.

    2016-02-01

    The fluorescent nature of aerosol at a high-altitude Alpine site was studied using a wide-band integrated bioaerosol (WIBS-4) single particle multi-channel ultraviolet - light-induced fluorescence (UV-LIF) spectrometer. This was supported by comprehensive cloud microphysics and meteorological measurements with the aims of cataloguing concentrations of bio-fluorescent aerosols at this high-altitude site and also investigating possible influences of UV-fluorescent particle types on cloud-aerosol processes. Analysis of background free tropospheric air masses, using a total aerosol inlet, showed there to be a minor increase in the fluorescent aerosol fraction during in-cloud cases compared to out-of-cloud cases. The size dependence of the fluorescent aerosol fraction showed the larger aerosol to be more likely to be fluorescent with 80 % of 10 μm particles being fluorescent. Whilst the fluorescent particles were in the minority (NFl/NAll = 0.27 ± 0.19), a new hierarchical agglomerative cluster analysis approach, Crawford et al. (2015) revealed the majority of the fluorescent aerosols were likely to be representative of fluorescent mineral dust. A minor episodic contribution from a cluster likely to be representative of primary biological aerosol particles (PBAP) was also observed with a wintertime baseline concentration of 0.1 ± 0.4 L-1. Given the low concentration of this cluster and the typically low ice-active fraction of studied PBAP (e.g. pseudomonas syringae), we suggest that the contribution to the observed ice crystal concentration at this location is not significant during the wintertime.

  8. Observations of fluorescent aerosol-cloud interactions in the free troposphere at the Sphinx high Alpine research station, Jungfraujoch

    NASA Astrophysics Data System (ADS)

    Crawford, I.; Lloyd, G.; Bower, K. N.; Connolly, P. J.; Flynn, M. J.; Kaye, P. H.; Choularton, T. W.; Gallagher, M. W.

    2015-09-01

    The fluorescent nature of aerosol at a high Alpine site was studied using a wide-band integrated bioaerosol (WIBS-4) single particle multi-channel ultra violet-light induced fluorescence (UV-LIF) spectrometer. This was supported by comprehensive cloud microphysics and meteorological measurements with the aims of cataloguing concentrations of bio-fluorescent aerosols at this high altitude site and also investigating possible influences of UV-fluorescent particle types on cloud-aerosol processes. Analysis of background free tropospheric air masses, using a total aerosol inlet, showed there to be a minor but statistically insignificant increase in the fluorescent aerosol fraction during in-cloud cases compared to out of cloud cases. The size dependence of the fluorescent aerosol fraction showed the larger aerosol to be more likely to be fluorescent with 80 % of 10 μm particles being fluorescent. Whilst the fluorescent particles were in the minority (NFl/NAll = 0.27±0.19), a new hierarchical agglomerative cluster analysis approach, Crawford et al. (2015) revealed the majority of the fluorescent aerosol were likely to be representative of fluorescent mineral dust. A minor episodic contribution from a cluster likely to be representative of primary biological aerosol particles (PBAP) was also observed with a wintertime baseline concentration of 0.1±0.4 L-1. Given the low concentration of this cluster and the typically low ice active fraction of studied PBAP (e.g. pseudomonas syringae) we suggest that the contribution to the observed ice crystal concentration at this location is not significant during the wintertime.

  9. EVALUATION OF ACOUSTIC FORCES ON A PARTICLE IN AEROSOL MEDIUM

    SciTech Connect

    Lee, S; Richard Dimenna, R

    2007-09-27

    The acoustic force exerted on a solid particle was evaluated to develop a fundamental understanding of the critical physical parameters or constraints affecting particle motion and capture in a collecting device. The application of an acoustic force to the collection of a range of submicron-to-micron particles in a highly turbulent airflow stream laden with solid particles was evaluated in the presence of other assisting and competing forces. This scoping estimate was based on the primary acoustic force acting directly on particles in a dilute aerosol system, neglecting secondary interparticle effects such as agglomeration of the sub-micron particles. A simplified analysis assuming a stable acoustic equilibrium with an infinite sound speed in the solid shows that for a solid-laden air flow in the presence of a standing wave, particles will move toward the nearest node. The results also show that the turbulent drag force on a 1-{micro}m particle resulting from eddy motion is dominant when compared with the electrostatic force or the ultrasonic acoustic force. At least 180 dB acoustic pressure level at 1 MHz is required for the acoustic force to be comparable to the electrostatic or turbulent drag forces in a high-speed air stream. It is noted that particle size and pressure amplitude are dominant parameters for the acoustic force. When acoustic pressure level becomes very large, the acoustic energy will heat up the surrounding air medium, which may cause air to expand. With an acoustic power of about 600 watts applied to a 2000-lpm air flow, the air temperature can increase by as much as 15 C at the exit of the collector.

  10. CCN frequency distributions and aerosol chemical composition from long-term observations at European ACTRIS supersites

    NASA Astrophysics Data System (ADS)

    Decesari, Stefano; Rinaldi, Matteo; Schmale, Julia Yvonne; Gysel, Martin; Fröhlich, Roman; Poulain, Laurent; Henning, Silvia; Stratmann, Frank; Facchini, Maria Cristina

    2016-04-01

    Cloud droplet number concentration is regulated by the availability of aerosol acting as cloud condensation nuclei (CCN). Predicting the air concentrations of CCN involves knowledge of all physical and chemical processes that contribute to shape the particle size distribution and determine aerosol hygroscopicity. The relevance of specific atmospheric processes (e.g., nucleation, coagulation, condensation of secondary organic and inorganic aerosol, etc.) is time- and site-dependent, therefore the availability of long-term, time-resolved aerosol observations at locations representative of diverse environments is strategic for the validation of state-of-the-art chemical transport models suited to predict CCN concentrations. We focused on long-term (year-long) datasets of CCN and of aerosol composition data including black carbon, and inorganic as well as organic compounds from the Aerosol Chemical Speciation Monitor (ACSM) at selected ACTRIS supersites (http://www.actris.eu/). We discuss here the joint frequency distribution of CCN levels and of aerosol chemical components concentrations for two stations: an alpine site (Jungfraujoch, CH) and a central European rural site (Melpitz, DE). The CCN frequency distributions at Jungfraujoch are broad and generally correlated with the distributions of the concentrations of aerosol chemical components (e.g., high CCN concentrations are most frequently found for high organic matter or black carbon concentrations, and vice versa), which can be explained as an effect of the strong seasonality in the aerosol characteristics at the mountain site. The CCN frequency distributions in Melpitz show a much weaker overlap with the distributions of BC concentrations or other chemical compounds. However, especially at high CCN concentration levels, a statistical correlation with organic matter (OM) concentration can be observed. For instance, the number of CCN (with particle diameter between 20 and 250 nm) at a supersaturation of 0.7% is

  11. Exploring Atmospheric Aerosol Chemistry with Advanced High-Resolution Mass Spectrometry and Particle Imaging Methods

    NASA Astrophysics Data System (ADS)

    Nizkorodov, S.

    2014-12-01

    Physical and chemical complexity of atmospheric aerosols presents significant challenges both to experimentalists working on aerosol characterization and to modelers trying to parameterize critical aerosol properties. Multi-modal approaches that combine state-of-the-art experimental, theoretical, and modeling methods are becoming increasingly important in aerosol research. This presentation will discuss recent applications of unique high-resolution mass spectrometry and particle imaging tools developed at two Department of Energy's user facilities, the Environmental Molecular Science Laboratory (EMSL) and Advanced Light Source (ALS), to studies of molecular composition, photochemical aging, and properties of laboratory-generated and field aerosols. Specifically, this presentation will attempt to address the following questions: (a) how do NO2, SO2, and NH3 affect molecular level composition of anthropogenic aerosols?; (b) what factors determine viscosity/surface tension of organic aerosol particles?; (c) how does photolysis affect molecular composition and optical properties of organic aerosols?

  12. Particle Deposition in a Child Respiratory Tract Model: In Vivo Regional Deposition of Fine and Ultrafine Aerosols in Baboons

    PubMed Central

    Albuquerque-Silva, Iolanda; Vecellio, Laurent; Durand, Marc; Avet, John; Le Pennec, Déborah; de Monte, Michèle; Montharu, Jérôme; Diot, Patrice; Cottier, Michèle; Dubois, Francis; Pourchez, Jérémie

    2014-01-01

    To relate exposure to adverse health effects, it is necessary to know where particles in the submicron range deposit in the respiratory tract. The possibly higher vulnerability of children requires specific inhalation studies. However, radio-aerosol deposition experiments involving children are rare because of ethical restrictions related to radiation exposure. Thus, an in vivo study was conducted using three baboons as a child respiratory tract model to assess regional deposition patterns (thoracic region vs. extrathoracic region) of radioactive polydisperse aerosols ([d16–d84], equal to [0.15 µm–0.5 µm], [0.25 µm–1 µm], or [1 µm–9 µm]). Results clearly demonstrated that aerosol deposition within the thoracic region and the extrathoraic region varied substantially according to particle size. High deposition in the extrathoracic region was observed for the [1 µm–9 µm] aerosol (72%±17%). The [0.15 µm–0.5 µm] aerosol was associated almost exclusively with thoracic region deposition (84%±4%). Airborne particles in the range of [0.25 µm–1 µm] showed an intermediate deposition pattern, with 49%±8% in the extrathoracic region and 51%±8% in the thoracic region. Finally, comparison of baboon and human inhalation experiments for the [1 µm–9 µm] aerosol showed similar regional deposition, leading to the conclusion that regional deposition is species-independent for this airborne particle sizes. PMID:24787744

  13. 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.

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

    DOEpatents

    Novick, V.J.

    1998-10-06

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

  15. Seasonal Aerosol Distributions at Summit, Greenland: EC, OC, 14C and Individual Particle Analysis

    NASA Astrophysics Data System (ADS)

    Klouda, G. A.; Conny, J. M.; McNichol, A. P.; Dibb, J. E.

    2011-12-01

    Aerosol is known to affect the Earth's atmosphere and surface albedo thus having an influence on climate. In the case of carbonaceous aerosol, organic carbon (OC) tends to scatter sunlight while elemental (soot) carbon (EC) aerosol absorbs light. Considering the importance of these aerosols on snow and ice albedo (Hansen and Nazarenko, 2004), PM2.5, PM2.5-10 and snow-melt filters were collected weekly at Summit, Greenland from August 2000 to August 2002 to measure particulate EC, OC, and 14C of total carbon; the latter to quantify natural and anthropogenic source contributions. The pattern of PM2.5 shows a spring-summer maxima in EC (~10 ng m-3) and OC (~ 100 ng m-3); with levels consistent with summer 2006 measurements reported by Hagler et al. (2007). For a subset of filters over the two year period, the average biogenic contribution to PM2.5 OC was estimated to be 20 ng m-3 considering an average percent modern carbon of 46 % (SD=18 %; n=21) and an average total carbon concentration of 50 ng m-3. A summer maximum was observed in PM2.5-10 OC (~ 1000 ng m-3), while for the most part EC concentrations were below detection (< 300 ng m-3; limited primarily by the volume of air sampled). To provide insight into scattering and absorption properties of aerosols at Summit, we used scanning electron microscopy (SEM) to investigate the size, shape, and chemistry of particle populations as well as individual particles from selected filters. Particles were migrated from the filters to polished silicon or germanium wafers using an electrostatically-assisted centrifugation technique. Particle populations were studied by employing secondary electron imaging and energy dispersive x-ray spectroscopy (EDX) with automated SEM and associated particle analysis software. The size, shape, and composition of individual particles were studied with field-emission SEM employing secondary and backscatter electron imaging, bright-field and dark-field scanning transmission electron microscopy

  16. Real-time chemical analysis of aerosol particles

    SciTech Connect

    Yang, M.; Whitten, W.B.; Ramsey, J.M.

    1995-04-01

    An important aspect of environmental atmospheric monitoring requires the characterization of airborne microparticles and aerosols. Unfortunately, traditional sample collection and handling techniques are prone to contamination and interference effects that can render an analysis invalid. These problems can be avoided by using real-time atmospheric sampling techniques followed by immediate mass spectrometric analysis. The former is achieved in these experiments via a two state differential pumping scheme that is attached directly to a commercially available quadruple ion trap mass spectrometer. Particles produced by an external particle generator enter the apparatus and immediately pass through two cw laser/fiberoptic based detectors positioned two centimeters apart. Timing electronics measure the time between detection events, estimate the particles arrival in the center of the ion trap and control the firing of a YAG laser. Ions produced when the UV laser light ablates the particle`s surface are stored by the ion trap for mass analysis. Ion trap mass spectrometers have several advantages over conventional time-of-flight instruments. First, they are capable of MS/MS analysis by the collisional dissociation of a stored species, This permits complete chemical characterization of airborne samples. Second, ion traps are small and lend themselves to portable, field oriented applications.

  17. Pathfinder Instruments for Cloud and Aerosol Spaceborne Observations (PICASSO)

    NASA Technical Reports Server (NTRS)

    McCormick, M. Patrick; Winker, David M.

    1998-01-01

    This paper will describe the planned 3-year Pathfinder Instruments for Cloud and Aerosol Spaceborne Observations (PICASSO) mission, its instrumentation and implementation. It will use LITE and other data, plus analyses, to show the feasibility of such a mission. PICASSO is being proposed for NASA's Earth System Science Pathfinder (ESSP) program with launch predicted in 2003.

  18. Real-Time Detection Method And System For Identifying Individual Aerosol Particles

    DOEpatents

    Gard, Eric Evan; Fergenson, David Philip

    2005-10-25

    A method and system of identifying individual aerosol particles in real time. Sample aerosol particles are compared against and identified with substantially matching known particle types by producing positive and negative test spectra of an individual aerosol particle using a bipolar single particle mass spectrometer. Each test spectrum is compared to spectra of the same respective polarity in a database of predetermined positive and negative spectra for known particle types and a set of substantially matching spectra is obtained. Finally the identity of the individual aerosol particle is determined from the set of substantially matching spectra by determining a best matching one of the known particle types having both a substantially matching positive spectrum and a substantially matching negative spectrum associated with the best matching known particle type.

  19. Chemical compositions of black carbon particle cores and coatings via soot particle aerosol mass spectrometry with photoionization and electron ionization.

    PubMed

    Canagaratna, Manjula R; Massoli, Paola; Browne, Eleanor C; Franklin, Jonathan P; Wilson, Kevin R; Onasch, Timothy B; Kirchstetter, Thomas W; Fortner, Edward C; Kolb, Charles E; Jayne, John T; Kroll, Jesse H; Worsnop, Douglas R

    2015-05-14

    Black carbon is an important constituent of atmospheric aerosol particle matter (PM) with significant effects on the global radiation budget and on human health. The soot particle aerosol mass spectrometer (SP-AMS) has been developed and deployed for real-time ambient measurements of refractory carbon particles. In the SP-AMS, black carbon or metallic particles are vaporized through absorption of 1064 nm light from a CW Nd:YAG laser. This scheme allows for continuous "soft" vaporization of both core and coating materials. The main focus of this work is to characterize the extent to which this vaporization scheme provides enhanced chemical composition information about aerosol particles. This information is difficult to extract from standard SP-AMS mass spectra because they are complicated by extensive fragmentation from the harsh 70 eV EI ionization scheme that is typically used in these instruments. Thus, in this work synchotron-generated vacuum ultraviolet (VUV) light in the 8-14 eV range is used to measure VUV-SP-AMS spectra with minimal fragmentation. VUV-SP-AMS spectra of commercially available carbon black, fullerene black, and laboratory generated flame soots were obtained. Small carbon cluster cations (C(+)-C5(+)) were found to dominate the VUV-SP-AMS spectra of all the samples, indicating that the corresponding neutral clusters are key products of the SP vaporization process. Intercomparisons of carbon cluster ratios observed in VUV-SP-AMS and SP-AMS spectra are used to confirm spectral features that could be used to distinguish between different types of refractory carbon particles. VUV-SP-AMS spectra of oxidized organic species adsorbed on absorbing cores are also examined and found to display less thermally induced decomposition and fragmentation than spectra obtained with thermal vaporization at 200 °C (the minimum temperature needed to quantitatively vaporize ambient oxidized organic aerosol with a continuously heated surface). The particle cores

  20. Comparing regional modeling (CHIMERE) and satellite observations of aerosols (PARASOL): Methodology and case study over Mexico

    NASA Astrophysics Data System (ADS)

    Stromatas, Stavros

    2010-05-01

    S. Stromatas (1), S. Turquety (1), H. Chepfer (1), L. Menut (1), B. Bessagnet (2), JC Pere (2), D. Tanré (3) . (1) Laboratoire de Météorologie Dynamique, CNRS/IPSL, École Polytechnique, 91128 Palaiseau Cedex, France, (2) INERIS, Institut National de l'Environnement Industriel et des Risques, Parc technologique ALATA, 60550 Verneuil en Halatte, FRANCE, (3) Laboratoire d'Optique Atmosphérique/CNRS Univ. des Sciences et Tech. de Lille, 59650 - Villeneuve d'Ascq, France. Atmospheric suspended particles (aerosols) have significant radiative and environmental impacts, affecting human health, visibility and climate. Therefore, they are regulated by air quality standards worldwide, and monitored by regional observation networks. Satellite observations vastly improve the horizontal and temporal coverage, providing daily distributions. Aerosols are currently estimated using aerosol optical depth (AOD) retrievals, a quantitative measure of the extinction of solar radiation by aerosol scattering and absorption between the point of observation and the top of the atmosphere. Even though remarkable progresses in aerosol modeling by chemistry-transport models (CTM) and measurement experiments have been made in recent years, there is still a significant divergence between the modeled and observed results. However, AOD retrievals from satellites remains a highly challenging task mostly because it depends on a variety of different parameters such as cloud contamination, surface reflectance contributions and a priori assumptions on aerosol types, each one of them incorporating its own difficulties. Therefore, comparisons between CTM and observations are often difficult to interpret. In this presentation, we will discuss comparisons between regional modeling (CHIMERE CTM) over Mexico and satellite observations obtained by the POLDER instrument embarked on PARASOL micro-satellite. After a comparison of the model AOD with the retrieved L2 AOD, we will present an alternative

  1. Liquid-liquid phase separation in aerosol particles: Imaging at the Nanometer Scale

    SciTech Connect

    O'Brien, Rachel; Wang, Bingbing; Kelly, Stephen T.; Lundt, Nils; You, Yuan; Bertram, Allan K.; Leone, Stephen R.; Laskin, Alexander; Gilles, Mary K.

    2015-04-21

    Atmospheric aerosols can undergo phase transitions including liquid-liquid phase separation (LLPS) while responding to changes in the ambient relative humidity (RH). Here, we report results of chemical imaging experiments using environmental scanning electron microscopy (ESEM) and scanning transmission x-ray microscopy (STXM) to investigate the LLPS of micron sized particles undergoing a full hydration-dehydration cycle. Internally mixed particles composed of ammonium sulfate (AS) and either: limonene secondary organic carbon (LSOC), a, 4-dihydroxy-3-methoxybenzeneaceticacid (HMMA), or polyethylene glycol (PEG-400) were studied. Events of LLPS with apparent core-shell particle morphology were observed for all samples with both techniques. Chemical imaging with STXM showed that both LSOC/AS and HMMA/AS particles were never homogeneously mixed for all measured RH’s above the deliquescence point and that the majority of the organic component was located in the shell. The shell composition was estimated as 65:35 organic: inorganic in LSOC/AS and as 50:50 organic: inorganic for HMMA/AS. PEG-400/AS particles showed fully homogeneous mixtures at high RH and phase separated below 89-92% RH with an estimated 50:50% organic to inorganic mix in the shell. These two chemical imaging techniques are well suited for in-situ analysis of the hygroscopic behavior, phase separation, and surface composition of collected ambient aerosol particles.

  2. Detection of biological particles in ambient air using bio-aerosol mass spectrometry

    NASA Astrophysics Data System (ADS)

    McJimpsey, Erica L.; Steele, Paul T.; Coffee, Keith R.; Fergenson, David P.; Riot, Vincent J.; Woods, Bruce W.; Gard, Eric E.; Frank, Matthias; Tobias, Herbert J.; Lebrilla, Carlito

    2006-05-01

    The Bio-Aerosol Mass Spectrometry (BAMS) system is an instrument used for the real time detection and identification of biological aerosols. Particles are drawn from the atmosphere directly into vacuum and tracked as they scatter light from several continuous wave lasers. After tracking, the fluorescence of individual particles is excited by a pulsed 266nm or 355nm laser. Molecules from those particles with appropriate fluorescence properties are subsequently desorbed and ionized using a pulsed 266nm laser. Resulting ions are analyzed in a dual polarity mass spectrometer. During two field deployments at the San Francisco International Airport, millions of ambient particles were analyzed and a small but significant fraction were found to have fluorescent properties similar to Bacillus spores and vegetative cells. Further separation of non-biological background particles from potential biological particles was accomplished using laser desorption/ionization mass spectrometry. This has been shown to enable some level of species differentiation in specific cases, but the creation and observation of higher mass ions is needed to enable a higher level of specificity across more species. A soft ionization technique, matrix-assisted laser desorption/ionization (MALDI) is being investigated for this purpose. MALDI is particularly well suited for mass analysis of biomolecules since it allows for the generation of molecular ions from large mass compounds that would fragment under normal irradiation. Some of the initial results from a modified BAMS system utilizing this technique are described.

  3. Detection of biological particles in ambient air using Bio-Aerosol Mass Spectrometry

    SciTech Connect

    McJimpsey, E L; Steele, P T; Coffee, K R; Fergenson, D P; Riot, V J; Woods, B W; Gard, E E; Frank, M; Tobias, H J; Lebrilla, C

    2006-03-16

    The Bio-Aerosol Mass Spectrometry (BAMS) system is an instrument used for the real time detection and identification of biological aerosols. Particles are drawn from the atmosphere directly into vacuum and tracked as they scatter light from several continuous wave lasers. After tracking, the fluorescence of individual particles is excited by a pulsed 266nm or 355nm laser. Molecules from those particles with appropriate fluorescence properties are subsequently desorbed and ionized using a pulsed 266nm laser. Resulting ions are analyzed in a dual polarity mass spectrometer. During two field deployments at the San Francisco International Airport, millions of ambient particles were analyzed and a small but significant fraction were found to have fluorescent properties similar to Bacillus spores and vegetative cells. Further separation of non-biological background particles from potential biological particles was accomplished using laser desorption/ionization mass spectrometry. This has been shown to enable some level of species differentiation in specific cases, but the creation and observation of higher mass ions is needed to enable a higher level of specificity across more species. A soft ionization technique, matrix-assisted laser desorption/ionization (MALDI) is being investigated for this purpose. MALDI is particularly well suited for mass analysis of biomolecules since it allows for the generation of molecular ions from large mass compounds that would fragment under normal irradiation. Some of the initial results from a modified BAMS system utilizing this technique are described.

  4. TES Limb-Geometry Observations of Aerosols

    NASA Technical Reports Server (NTRS)

    Smith, Michael D.

    2003-01-01

    The Thermal Emission Spectrometer (TES) on-board Mars Global Surveyor (MGS) has a pointing mirror that allows observations in the plane of the orbit anywhere from directly nadir to far above either the forward or aft limbs for details about the TES instrument). Nadir-geometry observations are defined as those where the field-of-view contains the surface of Mars (even if the actual observation is at a high emission angle far from true nadir). Limb-geometry observations are defined as those where the line-of-sight of the observations does not intersect the surface. At a number of points along the MGS orbit (typically every 10 deg. or 20 deg. of latitude) a limb sequence is taken, which includes a stack of overlapping TES spectra from just below the limb to more than 120 km above the limb. A typical limb sequence has approx. 20 individual spectra, and the projected size of a TES pixel at the limb is 13 km.

  5. Individual aerosol particles in and below clouds along a Mt. Fuji slope: Modification of sea-salt-containing particles by in-cloud processing

    NASA Astrophysics Data System (ADS)

    Ueda, S.; Hirose, Y.; Miura, K.; Okochi, H.

    2014-02-01

    Sizes and compositions of atmospheric aerosol particles can be altered by in-cloud processing by absorption/adsorption of gaseous and particulate materials and drying of aerosol particles that were formerly activated as cloud condensation nuclei. To elucidate differences of aerosol particles before and after in-cloud processing, aerosols were observed along a slope of Mt. Fuji, Japan (3776 m a.s.l.) during the summer in 2011 and 2012 using a portable laser particle counter (LPC) and an aerosol sampler. Aerosol samples for analyses of elemental compositions were obtained using a cascade impactor at top-of-cloud, in-cloud, and below-cloud altitudes. To investigate composition changes via in-cloud processing, individual particles (0.5-2 μm diameter) of samples from five cases (days) collected at different altitudes under similar backward air mass trajectory conditions were analyzed using a transmission electron microscope (TEM) equipped with an energy dispersive X-ray analyzer. For most cases (four cases), most particles at all altitudes mainly comprised sea salts: mainly Na with some S and/or Cl. Of those, in two cases, sea-salt-containing particles with Cl were found in below-cloud samples, although sea-salt-containing particles in top-of-cloud samples did not contain Cl. This result suggests that Cl in the sea salt was displaced by other cloud components. In the other two cases, sea-salt-containing particles on samples at all altitudes were without Cl. However, molar ratios of S to Na (S/Na) of the sea-salt-containing particles of top-of-cloud samples were higher than those of below-cloud samples, suggesting that sulfuric acid or sulfate was added to sea-salt-containing particles after complete displacement of Cl by absorption of SO2 or coagulation with sulfate. The additional volume of sulfuric acid in clouds for the two cases was estimated using the observed S/Na values of sea-salt-containing particles. The estimation revealed that size changes by in

  6. Quantifying Aerosol Direct Effects from Broadband Irradiance and Spectral Aerosol Optical Depth Observations

    SciTech Connect

    Creekmore, Torreon N.; Joseph, Everette; Long, Charles N.; Li, Siwei

    2014-05-16

    We outline a methodology using broadband and spectral irradiances to quantify aerosol direct effects on the surface diffuse shortwave (SW) irradiance. Best Estimate Flux data span a 13 year timeframe at the Department of Energy Atmospheric Radiation Measurement Program’s Southern Great Plains (SGP) site. Screened clear-sky irradiances and aerosol optical depth (AOD), for solar zenith angles ≤ 65°, are used to estimate clear-sky diffuse irradiances. We validate against detected clear-sky observations from SGP’s Basic Radiation System (BRS). BRS diffuse irradiances were in accordance with estimates, producing a root-mean-square error and mean bias errors of 4.0 W/m2 and -1.4 W/m2, respectively. Absolute differences show 99% of estimates within ±10 W/m2 (10%) of the mean BRS observations. Clear-sky diffuse estimates are used to derive quantitative estimates of aerosol radiative effects, represented as the aerosol diffuse irradiance (ADI). ADI is the contribution of diffuse SW to global SW, attributable to scattering of atmospheric transmission by natural plus anthropogenic aerosols. Estimated slope for the ADI as a function of AOD indicates an increase of ~22 W/m2 in diffuse SW for every 0.1 increase in AOD. Such significant increases in the diffuse fraction could possibly increase photosynthesis. Annual mean ADI is 28.2 W/m2, and heavy aerosol loading at SGP provides up to a maximum increase of 120 W/m2 in diffuse SW over background conditions. With regard to seasonal variation, the mean diffuse forcings are 17.2, 33.3, 39.0, and 23.6 W/m2 for winter, spring, summer, and fall, respectively.

  7. A Survey of Airborne Observations of Biological Aerosol over the Continental United States during NASA SEAC4RS

    NASA Astrophysics Data System (ADS)

    Ziemba, L. D.; Venkateswaran, K.; Froyd, K.; Dibb, J. E.; Beyersdorf, A. J.; Chen, G.; Crumeyrolle, S.; Hudgins, C.; Lin, J. J.; Moore, R.; Thornhill, K. L.; Winstead, E.; Anderson, B. E.

    2013-12-01

    Aerosols play a significant role in regulating Earth's climate. Biological aerosols exist in the atmosphere in many forms including bacteria, fungal spores, pollens, viruses, and plant detritus. While laboratory studies have illustrated the potential for biological aerosol to act as efficient ice nuclei, ambient observations do not clearly show the significance of this mechanism for ice formation. Particularly lacking for assessing the role of biological aerosol on cloud processes are observations of the vertical extent of biological aerosol, especially in conjunction with strong convection as a pathway for redistributing particles from surface sources to the free troposphere. An extensive suite of instrumentation measuring aerosol chemical, physical, and optical properties was deployed aboard the NASA DC-8 aircraft during the SEAC4RS campaign (Studies of Emissions and Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys) in August/September of 2013. Flights were focused on characterizing emissions and transport of aerosols in the Southeast United States, a region characterized by strong biogenic activity. Additionally, convection associated with the North American Monsoon and Atlantic-basin hurricanes was targeted. Airborne biological aerosol was specifically measured during SEAC4RS with a Wideband Integrated Bioaerosol Sensor (WIBS-4A, Droplet Measurement Technologies). WIBS-4A utilizes a single-particle laser-induced fluorescence technique at two excitation wavelengths (280nm and 370nm) to identify biological aerosol, in addition to simultaneous determination of optical size and asymmetry factor for particles with diameter greater than 800nm. Single-particle mass spectrometry coupled with filter-based chemical composition and bacterial speciation analyses will be used to assess relationships with co-emitted mineral dusts. Vertical profiles for the background atmosphere will be compared to profiles influenced by convective storms to assess

  8. Impacts of aerosol particles on the microphysical and radiative properties of stratocumulus clouds over the southeast Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Twohy, C. H.; Anderson, J. R.; Toohey, D. W.; Andrejczuk, M.; Adams, A.; Lytle, M.; George, R. C.; Wood, R.; Saide, P.; Spak, S.; Zuidema, P.; Leon, D.

    2013-03-01

    there. Thus, larger scale forcings that impact cloud macrophysical properties, as well as enhanced aerosol particles, are important in determining cloud droplet size and cloud albedo. Differences in the size distribution of droplet residual particles and ambient aerosol particles were observed. By progressively excluding small droplets from the CVI sample, we were able to show that the larger drops, some of which may initiate drizzle, contain the largest aerosol particles. Geometric mean diameters of droplet residual particles were larger than those of the below-cloud and above cloud distributions. However, a wide range of particle sizes can act as droplet nuclei in these stratocumulus clouds. A detailed LES microphysical model was used to show that this can occur without invoking differences in chemical composition of cloud-nucleating particles.

  9. Ambient Observations of Organic Nitrogen Compounds in Submicrometer Aerosols in New York Using High Resolution Aerosol Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Zhou, S.; Ge, X.; Xu, J.; Sun, Y.; Zhang, Q.

    2015-12-01

    Organic nitrogen (ON) compounds, which include amines, nitriles, organic nitrates, amides, and N-containing aromatic heterocycles, are an important class of compounds ubiquitously detected in atmospheric particles and fog and cloud droplets. Previous studies indicate that these compounds can make up a significant fraction (20-80%) of the total nitrogen (N) content in atmospheric condensed phases and play important roles in new particle formation and growth and affecting the optical and hygroscopicity of aerosols. In this study, we report the observation of ON compounds in submicrometer particles (PM1) at two locations in New York based on measurements using Aerodyne high-resolution time-of-flight mass spectrometer (HR-ToF-AMS). One study was conducted as part of the US Department of Energy funded Aerosol Lifecyle - Intensive Operation Period (ALC-IOP) campaign at Brookhaven National Lab (BNL, 40.871˚N, 72.89˚W) in summer, 2011 and the other was conducted at the Queen's College (QC) in New York City (NYC) in summer, 2009. We observed a notable amount of N-containing organic fragment ions, CxHyNp+ and CxHyOzNp+, in the AMS spectra of organic aerosols at both locations and found that they were mainly associated with amino functional groups. Compared with results from lab experiments, the C3H8N+ at m/z = 58 was primarily attributed to trimethylamine. In addition, a significant amount of organonitrates was observed at BNL. Positive matrix factorization (PMF) analysis of the high resolution mass spectra (HRMS) of organic aerosols identified a unique nitrogen-enriched OA (NOA) factor with elevated nitrogen-to-carbon (N/C) at both BNL and QC. Analysis of the size distributions, volatility profiles, and correlations with external tracer indicates that acid-base reactions of amino compounds with sulfate and acidic gas were mainly responsible for the formation of amine salts. Photochemical production was also observed to play a role in the formation of NOA. Bivariate polar

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

    observed that the FBAP concentrations were very low. This may be due to the clean marine influx coming over the Indian Ocean and due to continuous wash out during the rain. While in case of sporadic rain events with fluctuating wind direction, high FBAP concentration was noticed. However such a similar trend was not observed for total aerosol particle concentration. The detailed results will be presented.

  11. Investigation of aerosol optical properties for remote sensing through DRAGON (distributed regional aerosol gridded observation networks) campaign in Korea

    NASA Astrophysics Data System (ADS)

    Lim, Jae-Hyun; Ahn, Joon Young; Park, Jin-Soo; Hong, You-Deok; Han, Jin-Seok; Kim, Jhoon; Kim, Sang-Woo

    2014-11-01

    Aerosols in the atmosphere, including dust and pollutants, scatters/absorbs solar radiation and change the microphysics of clouds, thus influencing the Earth's energy budget, climate, air quality, visibility, agriculture and water circulation. Pollutants have also been reported to threaten the human health. The present research collaborated with the U.S. NASA and the U.S. Aerosol Robotic Network (AERONET) is to study the aerosol characteristics in East Asia and improve the long-distance transportation monitoring technology by analyzing the observations of aerosol characteristics in East Asia during Distributed Regional Aerosol Gridded Observation Networks (DRAGON) Campaign (March 2012-May 2012). The sun photometers that measure the aerosol optical characteristics were placed evenly throughout the Korean Peninsula and concentrated in Seoul and the metropolitan area. Observation data are obtained from the DRAGON campaign and the first year (2012) observation data (aerosol optical depth and aerosol spatial distribution) are analyzed. Sun photometer observations, including aerosol optical depth (AOD), are utilized to validate satellite observations from Geostationary Ocean Color Imager (GOCI) and Moderate Resolution Imaging Spectroradiometer (MODIS). Additional analysis is performed associated with the Northeast Asia, the Korean Peninsula in particular, to determine the spatial distribution of the aerosol.

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

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

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

  13. Global aerosol typing from a combination of A-Train satellite observations in clear-sky and above clouds

    NASA Astrophysics Data System (ADS)

    Kacenelenbogen, M. S.; Russell, P. B.; Vaughan, M.; Redemann, J.; Shinozuka, Y.; Livingston, J. M.; Zhang, Q.

    2014-12-01

    According to the 5th Assessment Report of the Intergovernmental Panel on Climate Change (IPCC), the model estimates of Radiative Forcing due to aerosol-radiation interactions (RFari) for individual aerosol types are less certain than the total RFari [Boucher et al., 2013]. For example, the RFari specific to Black Carbon (BC) is uncertain due to an underestimation of its mass concentration near source regions [Koch et al., 2009]. Several recent studies have evaluated chemical transport model (CTM) predictions using observations of aerosol optical properties such as Aerosol Optical Depth (AOD) or Single Scattering Albedo (SSA) from satellite or ground-based instruments (e.g., Huneeus et al., [2010]). However, most passive remote sensing instruments fail to provide a comprehensive assessment of the particle type without further analysis and combination of measurements. To improve the predictions of aerosol composition in CTMs, we have developed an aerosol classification algorithm (called Specified Clustering and Mahalanobis Classification, SCMC) that assigns an aerosol type to multi-parameter retrievals by spaceborne, airborne or ground based passive remote sensing instruments [Russell et al., 2014]. The aerosol types identified by our scheme are pure dust, polluted dust, urban-industrial/developed economy, urban-industrial/developing economy, dark biomass smoke, light biomass smoke and pure marine. First, we apply the SCMC method to five years of clear-sky space-borne POLDER observations over Greece. We then use the aerosol extinction and SSA spectra retrieved from a combination of MODIS, OMI and CALIOP clear-sky observations to infer the aerosol type over the globe in 2007. Finally, we will extend the spaceborne aerosol classification from clear-sky to above low opaque water clouds using a combination of CALIOP AOD and backscatter observations and OMI absorption AOD values from near-by clear-sky pixels.

  14. Review: engineering particles using the aerosol-through-plasma method

    SciTech Connect

    Phillips, Jonathan; Luhrs, Claudia C; Richard, Monique

    2009-01-01

    For decades, plasma processing of materials on the nanoscale has been an underlying enabling technology for many 'planar' technologies, particularly virtually every aspect of modern electronics from integrated-circuit fabrication with nanoscale elements to the newest generation of photovoltaics. However, it is only recent developments that suggest that plasma processing can be used to make 'particulate' structures of value in fields, including catalysis, drug delivery, imaging, higher energy density batteries, and other forms of energy storage. In this paper, the development of the science and technology of one class of plasma production of particulates, namely, aerosol-through-plasma (A-T-P), is reviewed. Various plasma systems, particularly RF and microwave, have been used to create nanoparticles of metals and ceramics, as well as supported metal catalysts. Gradually, the complexity of the nanoparticles, and concomitantly their potential value, has increased. First, unique two-layer particles were generated. These were postprocessed to create unique three-layer nanoscale particles. Also, the technique has been successfully employed to make other high-value materials, including carbon nanotubes, unsupported graphene, and spherical boron nitride. Some interesting plasma science has also emerged from efforts to characterize and map aerosol-containing plasmas. For example, it is clear that even a very low concentration of particles dramatically changes plasma characteristics. Some have also argued that the local-thermodynamic-equilibrium approach is inappropriate to these systems. Instead, it has been suggested that charged- and neutral-species models must be independently developed and allowed to 'interact' only in generation terms.

  15. A one-dimensional model describing aerosol formation and evolution in the stratosphere. I - Physical processes and mathematical analogs. II - Sensitivity studies and comparison with observations

    NASA Technical Reports Server (NTRS)

    Turco, R. P.; Hamill, P.; Toon, O. B.; Whitten, R. C.; Kiang, C. S.

    1979-01-01

    A new time-dependent one-dimensional model of the stratospheric sulfate aerosol layer is developed. The model treats atmospheric photochemistry and aerosol physics in detail and includes the interaction between gases and particles explicitly. It is shown that the numerical algorithms used in the model are quite precise. Sensitivity studies and comparison with observations are made. The simulated aerosol physics generates a particle layer with most of the observed properties. The sensitivity of the calculated properties to changes in a large number of aeronomic aerosol parameters is discussed in some detail. The sensitivity analysis reveals areas where the aerosol model is most uncertain. New observations are suggested that might help resolve important questions about the origin of the stratospheric aerosol layer.

  16. Chemical and Physical Properties of Bulk Aerosols within Four Sectors Observed during TRACE-P

    NASA Technical Reports Server (NTRS)

    Jordan, C. E.; Anderson, B. E.; Talbot, R. W.; Dibb, J. E.; Fuelberg, E.; Hudgins, C. H.; Kiley, C. M.; Russo, R.; Scheuer, E.; Seid, G.

    2003-01-01

    Chemical and physical aerosol data collected on the DC-8 during TRACE-P were grouped into four sectors based on back trajectories. The four sectors represent long-range transport from the west (WSW), regional circulation over the western Pacific and Southeast Asia (SE Asia), polluted transport from Northern Asia with substantial sea salt at low altitudes (NNW) and a substantial amount of dust (Channel). WSW has generally low mixing ratios at both middle and high altitudes, with the bulk of the aerosol mass due to non-sea-salt water-soluble inorganic species. Low altitude SE Asia also has low mean mixing ratios in general, with the majority of the aerosol mass comprised of non-sea-salts, however, soot is also relatively important m this region. "w had the highest mean sea salt mixing ratios, with the aerosol mass at low altitudes (a km) evenly divided between sea salts, mm-sea-salts, and dust. The highest mean mixing ratios of water-soluble ions and soot were observed at the lowest altitudes (a km) in the Channel sector. The bulk of the aerosol mass exported from Asia emanates h m Channel at both low and midaltitudes, due to the prevalence of dust compared to other sectors. Number densities show enhanced fine particles for Channel and NNW, while their volume distributions are enhanced due to sea salt and dust Low-altitude Channel exhibits the highest condensation nuclei ((34) number densities along with enhanced scattering coefficients, compared to the other sectors. At midaltitudes (2-7 km), low mean CN number densities coupled with a high proportion of nonvolatile particles (265%) observed in polluted sectors (Channel and NNW) are attributed to wet scavenging which removes hygroscopic CN particles. Low single scatter albedo m SE Asia reflects enhanced soot

  17. Chemical and physical properties of bulk aerosols within four sectors observed during TRACE-P

    NASA Astrophysics Data System (ADS)

    Jordan, C. E.; Anderson, B. E.; Talbot, R. W.; Dibb, J. E.; Fuelberg, H. E.; Hudgins, C. H.; Kiley, C. M.; Russo, R.; Scheuer, E.; Seid, G.; Thornhill, K. L.; Winstead, E.

    2003-11-01

    Chemical and physical aerosol data collected on the DC-8 during TRACE-P were grouped into four sectors based on back trajectories. The four sectors represent long-range transport from the west (WSW), regional circulation over the western Pacific and Southeast Asia (SE Asia), polluted transport from northern Asia with substantial sea salt at low altitudes (NNW) and a substantial amount of dust (Channel). WSW has generally low mixing ratios at both middle and high altitudes, with the bulk of the aerosol mass due to non-sea-salt water-soluble inorganic species. Low altitude SE Asia also has low mean mixing ratios in general, with the majority of the aerosol mass comprised of non-sea-salts, however, soot is also relatively important in this region. NNW had the highest mean sea salt mixing ratios, with the aerosol mass at low altitudes (<2 km) evenly divided between sea salts, non-sea-salts, and dust. The highest mean mixing ratios of water-soluble ions and soot were observed at the lowest altitudes (<2 km) in the Channel sector. The bulk of the aerosol mass exported from Asia emanates from Channel at both low and midaltitudes, due to the prevalence of dust compared to other sectors. Number densities show enhanced fine particles for Channel and NNW, while their volume distributions are enhanced due to sea salt and dust. Low-altitude Channel exhibits the highest condensation nuclei (CN) number densities along with enhanced scattering coefficients, compared to the other sectors. At midaltitudes (2-7 km), low mean CN number densities coupled with a high proportion of nonvolatile particles (≥65%) observed in polluted sectors (Channel and NNW) are attributed to wet scavenging which removes hygroscopic CN particles. Low single scatter albedo in SE Asia reflects enhanced soot.

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

  19. CRISM Limb Observations of Aerosols and Water Vapor

    NASA Technical Reports Server (NTRS)

    Smith, Michael D.; Wolff, M.J.; Clancy, R.T.; Seelos, F.; Murchie, S.L.

    2009-01-01

    Near-infrared spectra taken in a limb-viewing geometry by the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) on-board the Mars Reconnaissance Orbiter (MRO) provide a useful tool for probing atmospheric structure. Here we describe preliminary work on the retrieval of vertical profiles of aerosols and water vapor from the CRISM limb observations. The first full set of CRISM limb observations was taken in July 2009, with subsequent limb observations planned once every two months. Each set of limb observations contains about four dozen scans across the limb giving pole-to-pole coverage for two orbits at roughly 100 and 290 W longitude. Radiative transfer modeling taking account of aerosol scattering in the limb-viewing geometry is used to model the observations. The retrievals show the height to which dust and water vapor extend and the location and height of water ice clouds. Results from the First set of CRISM limb observations (July 2009, Ls=300) show dust aerosol well-mixed to about three scale heights above the surface with thin water ice clouds above the dust near the equator and at mid-northern latitudes. Water vapor is concentrated at high southern latitudes.

  20. Solid versus Liquid Particle Sampling Efficiency of Three Personal Aerosol Samplers when Facing the Wind

    PubMed Central

    Koehler, Kirsten A.; Anthony, T. Renee; Van Dyke, Michael

    2016-01-01

    The objective of this study was to examine the facing-the-wind sampling efficiency of three personal aerosol samplers as a function of particle phase (solid versus liquid). Samplers examined were the IOM, Button, and a prototype personal high-flow inhalable sampler head (PHISH). The prototype PHISH was designed to interface with the 37-mm closed-face cassette and provide an inhalable sample at 10 l min−1 of flow. Increased flow rate increases the amount of mass collected during a typical work shift and helps to ensure that limits of detection are met, particularly for well-controlled but highly toxic species. Two PHISH prototypes were tested: one with a screened inlet and one with a single-pore open-face inlet. Personal aerosol samplers were tested on a bluff-body disc that was rotated along the facing-the-wind axis to reduce spatiotemporal variability associated with sampling supermicron aerosol in low-velocity wind tunnels. When compared to published data for facing-wind aspiration efficiency for a mouth-breathing mannequin, the IOM oversampled relative to mannequin facing-the-wind aspiration efficiency for all sizes and particle types (solid and liquid). The sampling efficiency of the Button sampler was closer to the mannequin facing-the-wind aspiration efficiency than the IOM for solid particles, but the screened inlet removed most liquid particles, resulting in a large underestimation compared to the mannequin facing-the-wind aspiration efficiency. The open-face PHISH results showed overestimation for solid particles and underestimation for liquid particles when compared to the mannequin facing-the-wind aspiration efficiency. Substantial (and statistically significant) differences in sampling efficiency were observed between liquid and solid particles, particularly for the Button and screened-PHISH, with a majority of aerosol mass depositing on the screened inlets of these samplers. Our results suggest that large droplets have low penetration efficiencies

  1. Single-particle Analyses of Compositions, Morphology, and Viscosity of Aerosol Particles Collected During GoAmazon2014

    NASA Astrophysics Data System (ADS)

    Adachi, K.; Gong, Z.; Bateman, A. P.; Martin, S. T.; Cirino, G. G.; Artaxo, P.; Sedlacek, A. J., III; Buseck, P. R.

    2014-12-01

    Single-particle analysis using transmission electron microscopy (TEM) shows composition and morphology of individual aerosol particles collected during the GoAmazon2014 campaign. These TEM results indicate aerosol types and mixing states, both of which are important for evaluating particle optical properties and cloud condensation nuclei activity. The samples were collected at the T3 site, which is located in the Amazon forest with influences from the urban pollution plume from Manaus. Samples were also collected from the T0 site, which is in the middle of the jungle with minimal to no influences of anthropogenic sources. The aerosol particles mainly originated from 1) anthropogenic pollution (e.g., nanosphere soot, sulfate), 2) biogenic emissions (e.g., primary biogenic particles, organic aerosols), and 3) long-range transport (e.g., sea salts). We found that the biogenic organic aerosol particles contain homogeneously distributed potassium. Particle viscosity is important for evaluating gas-particle interactions and atmospheric chemistry for the particles. Viscosity can be estimated from the rebounding behavior at controlled relative humidities, i.e., highly viscous particles display less rebound on a plate than low-viscosity particles. We collected 1) aerosol particles from a plate (non-rebounded), 2) those that had rebounded from the plate and were then captured onto an adjacent sampling plate, and 3) particles from ambient air using a separate impactor sampler. Preliminary results show that more than 90% of non-rebounded particles consisted of nanosphere soot with or without coatings. The coatings mostly consisted of organic matter. Although rebounded particles also contain nanosphere soot (number fraction 64-69%), they were mostly internally mixed with sulfate, organic matter, or their mixtures. TEM tilted images suggested that the rebounded particles were less deformed on the substrate, whereas the non-rebounded particles were more deformed, which could

  2. Ultraviolet dust aerosol properties as observed by MARCI

    NASA Astrophysics Data System (ADS)

    Wolff, Michael J.; Todd Clancy, R.; Goguen, Jay D.; Malin, Michael C.; Cantor, Bruce A.

    2010-07-01

    Observations by the Mars Color Imager (MARCI) on board the Mars Reconnaissance Orbiter (MRO) in two ultraviolet (UV, Bands 6 and 7; 258 nm, and 320 nm, respectively) and one visible (Band 1, 436 nm) channels of the 2007 planet encircling dust storm are combined with those made by the two Mars Exploration Rovers (MERs) to better characterize the single scattering albedo (ω0) of martian dust aerosols. Exploiting the low contrast of the surface in the UV (and blue) as well as the reduced importance of surface reflectance under very dusty conditions, we utilize the sampling of photometric angles by the MARCI cross-track geometry to synthesize an analog of the classical Emergence Phase Function (EPF). This so-called "pseudo-EPF", used in conjunction with the "ground-truth" measurements provided by the MERs, is able to effectively isolate the effects of the dust ω0. The motivation for this approach is the elimination of a significant portion of the type of uncertainty involved in many previous radiative transfer analyses. Furthermore, we produce a self-consistent set of complex refractive indices (m=n+ik) through our use of an explicit microphysical representation of the aerosol scattering properties. Because of uncertainty in the exact size of the dust particles during the epoch of the observations, we consider two effective particle radii (reff) to cover the range anticipated from the literature: 1.6 and 1.8 μm. The resulting set of model-data comparisons, ω0, and m are presented along with an assessment of potential sources of error and uncertainty. Analysis of the Band 1 results is limited to ω0 as a "proof-of-concept" for our approach through a comparison to contemporaneous CRISM EPF results at 440 nm. The derived ω0 are: assuming reff=1.6μm-0.619-0.626,0.648, and 0.765, for Bands 6, 7, and 1, respectively; for reff=1.8μm-0.625-0.635,0.653,0.769, for the same band order. For either reff case, the total estimated error is 0.022, 0.019, and 0.010, again for

  3. Probing the micro-rheological properties of aerosol particles using optical tweezers

    NASA Astrophysics Data System (ADS)

    Power, Rory M.; Reid, Jonathan P.

    2014-07-01

    The use of optical trapping techniques to manipulate probe particles for performing micro-rheological measurements on a surrounding fluid is well-established. Here, we review recent advances made in the use of optical trapping to probe the rheological properties of trapped particles themselves. In particular, we review observations of the continuous transition from liquid to solid-like viscosity of sub-picolitre supersaturated solution aerosol droplets using optical trapping techniques. Direct measurements of the viscosity of the particle bulk are derived from the damped oscillations in shape following coalescence of two particles, a consequence of the interplay between viscous and surface forces and the capillary driven relaxation of the approximately spheroidal composite particle. Holographic optical tweezers provide a facile method for the manipulation of arrays of particles allowing coalescence to be controllably induced between two micron-sized aerosol particles. The optical forces, while sufficiently strong to confine the composite particle, are several orders of magnitude weaker than the capillary forces driving relaxation. Light, elastically back-scattered by the particle, is recorded with sub-100 ns resolution allowing measurements of fast relaxation (low viscosity) dynamics, while the brightfield image can be used to monitor the shape relaxation extending to times in excess of 1000 s. For the slowest relaxation dynamics studied (particles with the highest viscosity) the presence and line shape of whispering gallery modes in the cavity enhanced Raman spectrum can be used to infer the relaxation time while serving the dual purpose of allowing the droplet size and refractive index to be measured with accuracies of ±0.025% and ±0.1%, respectively. The time constant for the damped relaxation can be used to infer the bulk viscosity, spanning from the dilute solution limit to a value approaching that of a glass, typically considered to be >1012 Pa s, whilst

  4. Measurement, growth types and shrinkage of newly formed aerosol particles at an urban research platform

    NASA Astrophysics Data System (ADS)

    Salma, Imre; Németh, Zoltán; Weidinger, Tamás; Kovács, Boldizsár; Kristóf, Gergely

    2016-06-01

    Budapest platform for Aerosol Research and Training (BpART) was created for advancing long-term on-line atmospheric measurements and intensive aerosol sample collection campaigns in Budapest. A joint study including atmospheric chemistry or physics, meteorology, and fluid dynamics on several-year-long data sets obtained at the platform confirmed that the location represents a well-mixed, average atmospheric environment for the city centre. The air streamlines indicated that the host and neighbouring buildings together with the natural orography play an important role in the near-field dispersion processes. Details and features of the airflow structure were derived, and they can be readily utilised for further interpretations. An experimental method to determine particle diffusion losses in the differential mobility particle sizer (DMPS) system of the BpART facility was proposed. It is based on CPC-CPC (condensation particle counter) and DMPS-CPC comparisons. Growth types of nucleated particles observed in 4 years of measurements were presented and discussed specifically for cities. Arch-shaped size distribution surface plots consisting of a growth phase followed by a shrinkage phase were characterised separately since they supply information on nucleated particles. They were observed in 4.5 % of quantifiable nucleation events. The shrinkage phase took 1 h 34 min in general, and the mean shrinkage rate with standard deviation was -3.8 ± 1.0 nm h-1. The shrinkage of particles was mostly linked to changes in local atmospheric conditions, especially in global radiation and the gas-phase H2SO4 concentration through its proxy, or to atmospheric mixing in few cases. Some indirect results indicate that variations in the formation and growth rates of nucleated particles during their atmospheric transport could be a driving force of shrinkage for particles of very small sizes and on specific occasions.

  5. Observations of Sub-3 nm Particles and Sulfuric acid Concentrations during the Summer in Long Island, New York

    NASA Astrophysics Data System (ADS)

    You, Y.; Yu, H.; Weech, D.; Haller, G.; Mccubbin, I. B.; Chirokova, G.; Sedlacek, A. J.; Springston, S. R.; Wang, J.; Kuang, C.; McGraw, R. L.; Kanawade, V. P.; Lee, S.

    2011-12-01

    Atmospheric new particle formation (NPF) is an important source of aerosol particles. But the NPF processes are not well understood, in part because of our limited understanding of the formation of atmospheric sub-3 nm size aerosols and because of the limited number of simultaneous observations of particle size distributions and the aerosol nucleation precursors. During the 2011 (July - August) Aerosol Life Cycle Intensive Observation Period in Long Island, New York, we have measured aerosol number concentrations down to 1 nm with a particle size magnifier (a new technique developed by Airmodus to detect sub-3nm particles), aerosol size distributions larger than 3 nm with a scanning mobility particle spectrometer (SMPS), and concentrations of sulfuric acid (a key aerosol precursor) with a chemical ionization mass spectrometer (CIMS), along with a number of atmospheric trace gases and micron and sub-micron size particles. There were several different types of airmasses in our observation site during the summer, including long-range transported polluted or less polluted continental airmasses and relatively clean marine airmasses, mixed with local biogenic emissions. Our observation results show a very similar diurnal trend of sulfuric acid and total aerosol concentrations down to 1 nm during the daytime, consistent with our recent laboratory studies of sulfuric acid-ammonia-amine-water multicomponent nucleation that the formation of atmospheric sub-3 nm particles is largely due to sulfuric acid. However, the rise of sub-3 nm particle concentrations didn't always lead to NPF events characterized by typical banana shaped aerosol size distributions measured by SMPS. Additionally, there were also unexpected rises of sub-3 nm particles during the nighttime, with no sulfuric acid and when there were no NPF events. These results provide unique observation data needed to understand the atmospheric NPF processes in this observation site.

  6. Use of analytical electron microscopy for the individual particle analysis of the Arctic haze aerosol

    SciTech Connect

    Sheridan, P.J.

    1986-01-01

    To explore the usefulness of the analytical electron microscope for the analysis and source apportionment of individual aerosol particles, aerosol samples amenable to individual particle analysis were collected from a remote region. These samples were from the Arctic haze aerosol, and were collected on board a research aircraft during the Arctic Gas and Aerosol Sampling Program in spring 1983. Before elemental analysis by analytical electron microscopy (AEM) could be performed, an extensive relative sensitivity factor study was undertaken to calibrate the microscope/detector system for quanitative x-ray microanalysis. Subsequently determined elemental data, along with morphological information, were used to group the particles into classes with similar characteristics. Forty-seven classes of particles were found in the Arctic samples, the most populous classes containing H/sub 2/SO/sub 4/ droplets, carbonaceous particles, lithophilic particles, CaSO/sub 4/ or NaCl. Several classes containing anthropogenic particles were also identified.

  7. Aerosols, clouds, and precipitation in the North Atlantic trades observed during the Barbados aerosol cloud experiment - Part 1: Distributions and variability

    NASA Astrophysics Data System (ADS)

    Jung, Eunsil; Albrecht, Bruce A.; Feingold, Graham; Jonsson, Haflidi H.; Chuang, Patrick; Donaher, Shaunna L.

    2016-07-01

    Shallow marine cumulus clouds are by far the most frequently observed cloud type over the Earth's oceans; but they are poorly understood and have not been investigated as extensively as stratocumulus clouds. This study describes and discusses the properties and variations of aerosol, cloud, and precipitation associated with shallow marine cumulus clouds observed in the North Atlantic trades during a field campaign (Barbados Aerosol Cloud Experiment- BACEX, March-April 2010), which took place off Barbados where African dust periodically affects the region. The principal observing platform was the Center for Interdisciplinary Remotely Piloted Aircraft Studies (CIRPAS) Twin Otter (TO) research aircraft, which was equipped with standard meteorological instruments, a zenith pointing cloud radar and probes that measured aerosol, cloud, and precipitation characteristics.The temporal variation and vertical distribution of aerosols observed from the 15 flights, which included the most intense African dust event during all of 2010 in Barbados, showed a wide range of aerosol conditions. During dusty periods, aerosol concentrations increased substantially in the size range between 0.5 and 10 µm (diameter), particles that are large enough to be effective giant cloud condensation nuclei (CCN). The 10-day back trajectories showed three distinct air masses with distinct vertical structures associated with air masses originating in the Atlantic (typical maritime air mass with relatively low aerosol concentrations in the marine boundary layer), Africa (Saharan air layer), and mid-latitudes (continental pollution plumes). Despite the large differences in the total mass loading and the origin of the aerosols, the overall shapes of the aerosol particle size distributions were consistent, with the exception of the transition period.The TO was able to sample many clouds at various phases of growth. Maximum cloud depth observed was less than ˜ 3 km, while most clouds were less than 1 km

  8. GRASP Algorithm: retrieval of the aerosol properties over land surface from satellite observations (solicited)

    NASA Astrophysics Data System (ADS)

    Dubovik, Oleg; Litvinov, Pavel; Lapyonok, Tatyana; Ducos, Fabrice; Aspetsberger, Michael; Planer, Wolfgang; Federspiel, Christian; Fuertes, David

    The GRASP (Generalized Retrieval of Aerosol and Surface Properties) algorithm has been developed for enhanced characterization of the properties of both aerosol and land surface from diverse remote sensing observations. The concept of the algorithm is described in details by Dubovik et al. (2011). The algorithm is based on highly advanced statistically optimized fitting implemented as Multi-Term Least Square minimization (Dubovik, 2004) and deduces nearly 50 unknowns for each observed site. The algorithm derives a set of aerosol parameters similar to that derived by AERONET including detailed particle size distribution, the spectral dependence on the complex index of refraction and the fraction of non-spherical particles. The algorithm uses detailed aerosol and surface models and fully accounts for all multiple interactions of scattered solar light with aerosol, gases and the underlying surface. All calculations are done on-line without using traditional look-up tables. In addition, the algorithm can use the new multi-pixel concept - a simultaneous fitting of a large group of pixels with additional constraints limiting the time variability of surface properties and spatial variability of aerosol properties. This principle provides a possibility to improve retrieval for multiple observations even if the observations are not exactly co-incident or co-located. Significant efforts have been spent for optimization and speedup of the GRASP computer routine and retrievals from satellite observations. For example, the routine has been adapted for running at GPGPUs accelerators. Originally GRASP has been developed for POLDER/PARASOL multi-viewing imager and later adapted to a number of other satellite sensors such as MERIS at polar-orbiting platform and COCI/GOMS geostationary observations. The results of numerical tests and results of applications to real data will be presented. REFERENCES: Dubovik, et al.,“Statistically optimized inversion algorithm for enhanced

  9. Beyond single particle mass spectrometry: multidimensional characterisation of individual aerosol particles

    SciTech Connect

    Zelenyuk, Alla; Imre, D.

    2009-09-10

    The behavior of small aerosol particles depends on a number of their physical and chemical properties, many of which are strongly coupled. The size, internal composition, density, shape, morphology, hygroscopicity, index of refraction, activity as cloud condensation nuclei and ice nuclei, and other attributes of individual particles - all play a role in determining particle properties and their impacts. The traditional particle characterization approaches rely on separate parallel measurements that average over an ensemble of particles of different sizes and/or compositions and later attempt to draw correlations between them. As a result such studies overlook critical differences between particles and bulk and miss the fact that individual particles often exhibit major differences. Here we review the recently developed methods to simultaneously measure in-situ and in real time several of the attributes for individual particles using single particle mass spectrometer, SPLAT or its second generation SPLAT II. We also discuss novel approaches developed for classification, visualization and mining of large datasets produced by the multidimensional single particle characterization.

  10. Scavenging in weakly electrified saturated and subsaturated clouds, treating aerosol particles and droplets as conducting spheres

    NASA Astrophysics Data System (ADS)

    Zhou, Limin; Tinsley, Brian A.; Plemmons, Abigail

    2009-09-01

    The effects of electric charge on collision rate coefficients for scavenging of aerosol particles by droplets are evaluated, as appropriate to weak electrification conditions in clouds. Variations in charges on droplets and particles in clouds are proportional to the flow of current in the global electric circuit through gradients in resistivity, which are determined by gradients in droplet concentration and humidity. We obtain the collision rate coefficients by “trajectory model” calculations for spherical aerosol particles and droplets using the exact electrical force equation, with its long-range repulsion and short-range attraction, interacting with drag, inertia, and phoretic forces. The use of the exact electric force gives rate coefficients up to a factor of two greater than previous image charge calculations for particles in the “Greenfield Gap”. Rate coefficients for scavenging by Brownian diffusion are obtained by the analytic expression for “flux model” calculations. Rate coefficients for combined effects of electric and phoretic scavenging are given, as appropriate for scavenging of droplets evaporating to residual particles while temporarily retaining the original droplet charge. For particles of radii below about 0.1 μm and with charges typical of residues of freshly evaporated droplets, the long-range repulsive electrical force reduces the collision rate coefficients below those for phoretic scavenging in subsaturated air and below the rates for Brownian scavenging. Time constants for scavenging of particles are given for selected values of droplet size, particle and droplet charges, and particle density, and the applications to observed effects in the atmosphere are discussed.

  11. A ten-year global record of absorbing aerosols above clouds from OMI's near-UV observations

    NASA Astrophysics Data System (ADS)

    Jethva, Hiren; Torrres, Omar; Ahn, Changwoo

    2016-05-01

    Aerosol-cloud interaction continues to be one of the leading uncertain components of climate models, primarily due to the lack of an adequate knowledge of the complex microphysical and radiative processes associated with the aerosolcloud system. The situations when aerosols and clouds are found in the same atmospheric column, for instance, when light-absorbing aerosols such as biomass burning generated carbonaceous particles or wind-blown dust overlay low-level cloud decks, are commonly found over several regional of the world. Contrary to the cloud-free scenario over dark surface, for which aerosols are known to produce a net cooling effect (negative radiative forcing) on climate, the overlapping situation of absorbing aerosols over cloud can potentially exert a significant level of atmospheric absorption and produces a positive radiative forcing at top-of-atmosphere. The magnitude of direct radiative effects of aerosols above cloud depends directly on the aerosol loading, microphysical-optical properties of the aerosol layer and the underlying cloud deck, and geometric cloud fraction. We help in addressing this problem by introducing a novel product of optical depth of absorbing aerosols above clouds retrieved from near-UV observations made by the Ozone Monitoring Instrument (OMI) on board NASA's Aura platform. The presence of absorbing aerosols above cloud reduces the upwelling radiation reflected by cloud and produces a strong `color ratio' effect in the near-UV region, which can be unambiguously detected in the OMI measurements. Physically based on this effect, the OMACA algorithm retrieves the optical depths of aerosols and clouds simultaneously under a prescribed state of atmosphere. The algorithm architecture and results from a ten-year global record including global climatology of frequency of occurrence and above-cloud aerosol optical depth, and a discussion on related future field campaigns are presented.

  12. Where on Earth can we observe pristine aerosol?

    NASA Astrophysics Data System (ADS)

    Hamilton, Douglas; Carslaw, Ken; Spracklen, Dominick; Lee, Lindsay; Pringle, Kirsty; Reddington, Carly

    2014-05-01

    To understand how sensitive the climate is to greenhouse gas and aerosol emissions it is important to define the baseline from which the aerosol forcings are calculated [Carslaw et al., 2013]; but if no regions in the world are anthropogenically unaltered, where on Earth can we observe and learn about the behaviour of pristine environments? This question is relevant to both future modelling and long-term observational studies in climate science. Identification of such regions is also important if we are to fully understand climate response to natural aerosol changes [Spracklen and Rap, 2013]. Here we use a combination of model simulations and statistical emulation of the Global Model of Aerosol Processes (GLOMAP) to identify regions which are most pristine in today's atmosphere. The simulations are used to identify present day (PD) regions which have daily mean cloud condensation nuclei (CCN) concentration similar to pre-industrial (PI) levels. The emulation of an ensemble of perturbed parameter runs [Lee et al., 2013] for the PI and PD allows a full Monte Carlo variance-based sensitivity analysis of CCN to 28 different parameters, covering both natural and anthropogenic emissions and their processes, which affect the uncertainty in CCN concentrations. We use this information to assess which regions exhibit little change in the sensitivity the 28 parameters between the PI and PD. Potentially pristine environments are defined based on where both the CCN number concentration and its sensitivity to the 28 parameters have remained constant through the industrial period. Our results indicate that the low to mid-latitude maritime southern hemisphere is the most pristine region in the PD atmosphere, especially during the austral summer. Other pristine regions include Alaska and Yukon, the Melanesian islands and the Antarctic Peninsula. Simulated anthropogenic influence on CCN has high seasonality in the southern hemisphere but low seasonality in the northern hemisphere

  13. 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. PMID:23448102

  14. Summer Dust Aerosols Detected from CALIPSO Observations over the Tibetan Plateau

    NASA Technical Reports Server (NTRS)

    Huang, Jianping; Minnis, Patrick; Yi, Yuhong; Tang, Qiang; Wang, Xin; Hu, Yongxiang; Liu, Zhaoyan; Ayers, Kirk; Trepte, Charles; Winker, David

    2007-01-01

    Summertime Tibetan dust aerosol plumes are detected from the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) satellite. CALIPSO reveals that dust storms occur 4 times more frequently than previously found from Tibetan surface observations because few surface sites were available over remote northwestern Tibet. The Tibetan dust aerosol is characterized by column-averaged depolarization and color ratios around 21% and 0.83, respectively. The dust layers appear most frequently around 4-7 km above mean sea level. The depolarization ratio for about 90% of the dust particles is less than 10% at low altitudes (3-5 km), while only about 50% of the particles have a greater depolarization ratio at higher altitudes (7-10 km) suggesting a separation of larger irregular particles from smaller, near spherical ones during transport. The 4-day back trajectory analyses show that these plumes probably originate from the nearby Taklimakan desert surface and accumulate over the northern slopes of the Tibetan Plateau. These dust outbreaks can affect the radiation balance of the atmosphere of Tibet because they both absorb and reflect solar radiation.

  15. Estimate of municipal refuse incinerator contribution to Philadelphia aerosol using single particle analysis—II. Ambient measurements

    NASA Astrophysics Data System (ADS)

    Mamane, Y.

    In a study to differentiate between municipal refuse incinerator particles and other particles in urban air, samples were collected on Teflon and nuclepore filters in dichotomous samplers and analyzed by scanning electron microscopy (SEM) and energy dispersive X-ray spectrometry. The samples included ambient aerosol from two sites in the Philadelphia area, representing different meteorological conditions. The same samples were previously analyzed by bulk techniques including X-ray fluorescence and instrumental neutron activation analysis. Particles emitted from incinerators rich in Zn, Cl and K were clearly identified in ambient samples, both in the coarse (2.5-10 μm) and fine aerosol fraction (<2.5 μm). The contribution of incinerators emission was from zero up to 10% of the coarse aerosol mass. Similar particles that contained also Zn and Cl were observed, but they did not originate in refuse incineration. Minerals and biologicals were the most dominant components of the coarse aerosol fraction; sulfates dominate the fine fraction. One of the case studies provided evidence for the missing chlorine in the fine fraction. Apparently fine chlorides emitted from incinerators reacted with ambient sulfates to form mixed sulfates of Zn and K. Good agreement was obtained between the measured coarse aerosol mass concentration and the one estimated by electron microscopy.

  16. Detection and characterization of biological and other organic-carbon aerosol particles in atmosphere using fluorescence

    NASA Astrophysics Data System (ADS)

    Pan, Yong-Le

    2015-01-01

    This paper offers a brief review on the detection and characterization of biological and other organic-carbon (OC) aerosol particles in atmosphere using laser-induced-fluorescence (LIF) signatures. It focuses on single individual particles or aggregates in the micron and super-micron size range when they are successively drawn through the interrogation volume of a point detection system. Related technologies for these systems that have been developed in last two decades are also discussed. These results should provide a complementary view for studying atmospheric aerosol particles, particularly bioaerosol and OC aerosol particles from other analytical technologies.

  17. Individual Particle TOF-SIMS Imaging Analysis of Aerosol Collected During the April 2001 Asian Dust Event.

    NASA Astrophysics Data System (ADS)

    Peterson, R. E.

    2002-12-01

    included nitrates and sulfates. The Asian Dust samples were dominated by super-micrometer mineral aerosol. Principal Components Analysis, using the positive spectra of 6386 individual particles on the Asian dust impacted sample collected April 17, 2001 and 3415 individual particles on the background sample collected June 25, 2001 clearly separated the super-micrometer mineral aerosol from the sub-micrometer organic aerosol. Principal Component 1, which was the largest difference due to the Asian dust incursion, describes Mg, Si, Ca, and Fe as anti-correlated with the other major positive ion peaks for impactor stages 4 and 5 (approximately 1-3 micrometer aerodynamic diameter). Mixture models allowed separation of the aerosol collected on all 8 stages of the impactor into 14 classes. Observation of the differences in these particle classes between the Asian dust incursion sample and background SLC aerosol indicated again that the Asian dust dominated the 1-3 micrometer aerosol. Particle classes 1 through 5 were not found in the SLC background urban samples and were dominant in the 1-3 micrometer impactor stages of the April 17, 2001 sample. We thus feel that these classes describe the Asian dust impact on the SLC aerosol. The elements making up classes 1-5 include different ratios of Ca, Na, Mg, Si, K and Fe. These elements are typical of crustal dust. The higher classes (6-14) appear to include combustion products such as the C16 and C17 amides, phthalates, and hydrocarbons typical of petroleum use. These classes were dominant in the SLC urban background aerosol.

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

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

    NASA Technical Reports Server (NTRS)

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

    2015-01-01

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

  20. A theoretical study on gas-phase coating of aerosol particles

    SciTech Connect

    Jain, S.; Fotou, G.P.; Kodas, T.T.

    1997-01-01

    In situ coating of aerosol particles by gas-phase and surface reaction in a flow reactor is modeled accounting for scavenging (capture of small particles by large particles) and simultaneous surface reaction along with the finite sintering rate of the scavenged particles. A log-normal size distribution is assumed for the host and coating particles to describe coagulation and a monodisperse size distribution is used for the coating particles to describe sintering. As an example, coating of titania particles with silica in a continuous flow hot-wall reactor was modeled. High temperatures, low reactant concentrations, and large host particle surface areas favored smoother coatings in the parameter range: temperature 1,700--1,800 K, host particle number concentration 1 {times} 10{sup 5}--1 {times} 10{sup 7} No./cm{sup 3}, average host particle size 1 {micro}m, inlet coating reactant concentration (SiCl{sub 4}) 2 {times} 10{sup {minus}7}--2 {times} 10{sup {minus}10} mol/cm{sup 3}, and various surface reaction rates. The fraction of silica deposited on the TiO{sub 2} particles decreased by more than seven times with a hundredfold increase in SiCl{sub 4} inlet concentration because of the resulted increase in the average SiO{sub 2} particle size under the assumed coating conditions. Increasing the TiO{sub 2} particle number concentration resulted in higher scavenging efficiency of SiO{sub 2}. In the TiO{sub 2}/SiO{sub 2} system it is likely that surface reaction as well as scavenging play important roles in the coating process. The results agree qualitatively with experimental observations of TiO{sub 2} particles coated in situ with silica.

  1. Observations on the formation, growth and chemical composition of aerosols in an urban environment.

    PubMed

    Crilley, Leigh R; Jayaratne, E Rohan; Ayoko, Godwin A; Miljevic, Branka; Ristovski, Zoran; Morawska, Lidia

    2014-06-17

    The charge and chemical composition of ambient particles in an urban environment were determined using a neutral particle and air ion spectrometer and an aerodyne compact time-of-flight aerosol mass spectrometer. Particle formation and growth events were observed on 20 of the 36 days of sampling, with eight of these events classified as strong. During these events, peaks in the concentration of intermediate and large ions were followed by peaks in the concentration of ammonium and sulfate, which were not observed in the organic fraction. Comparison of days with and without particle formation events revealed that ammonium and sulfate were the dominant species on particle formation days while high concentrations of biomass burning OA inhibited particle growth. Analyses of the degree of particle neutralization lead us to conclude that an excess of ammonium enabled particle formation and growth. In addition, the large ion concentration increased sharply during particle growth, suggesting that during nucleation the neutral gaseous species ammonia and sulfuric acid react to form ammonium and sulfate ions. Overall, we conclude that the mechanism of particle formation and growth involved ammonia and sulfuric acid, with limited input from organics. PMID:24847803

  2. 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.

  3. 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

    . 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 factor to govern this trend. It is further observed that the CMD has good correlation with O3, SO2 and ambient RH, suggesting that possibly sulfate secondary materials have a substantial contribution in particle effective density. This approach can be useful for real-time measurement of effective density of both laboratory-generated and ambient aerosol particles, which is very important for studying the physico-chemical properties of particles.

  4. 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

    factor to govern this trend. It is further observed that the CMD has good correlation with O3, SO2 and ambient RH, suggesting that possibly sulfate secondary materials have substantial contribution in particle effective density. This approach can be useful for real-time measurement of effective density of both laboratory generated and ambient aerosol particles, which is very important for studying the physico-chemical property of particles.

  5. Impact of interannual variations in aerosol particle sources on orographic precipitation over California's Central Sierra Nevada

    NASA Astrophysics Data System (ADS)

    Creamean, J. M.; Ault, A. P.; White, A. B.; Neiman, P. J.; Ralph, F. M.; Minnis, P.; Prather, K. A.

    2015-01-01

    Aerosols that serve as cloud condensation nuclei (CCN) and ice nuclei (IN) have the potential to profoundly influence precipitation processes. Furthermore, changes in orographic precipitation have broad implications for reservoir storage and flood risks. As part of the CalWater field campaign (2009-2011), the variability and associated impacts of different aerosol sources on precipitation were investigated in the California Sierra Nevada using an aerosol time-of-flight mass spectrometer for precipitation chemistry, S-band profiling radar for precipitation classification, remote sensing measurements of cloud properties, and surface meteorological measurements. The composition of insoluble residues in precipitation samples collected at a surface site contained mostly local biomass burning and long-range transported dust and biological particles (2009), local sources of biomass burning and pollution (2010), and long-range transport from distant sources (2011). Although differences in the sources were observed from year-to-year, the most consistent source of dust and biological residues were associated with storms consisting of deep convective cloud systems with significant quantities of precipitation initiated in the ice phase. Further, biological residues were dominant (up to 40%) during storms with relatively warm cloud temperatures (up to -15 °C), supporting the important role bioparticles can play as ice nucleating particles. On the other hand, lower percentages of residues from local biomass burning and pollution were observed over the three winter seasons (on average 31 and 9%, respectively). When precipitation quantities were relatively low, these residues most likely served as CCN, forming smaller more numerous cloud droplets at the base of shallow cloud systems, and resulting in less efficient riming processes. The correlation between the source of aerosols within clouds and precipitation type and quantity will be further probed in models to understand the

  6. [Ultraviolet Mie lidar observations of aerosol extinction in a dust storm case over Macao].

    PubMed

    Liu, Qiao-jun; Cheng, A Y S; Zhu, Jian-hua; Fong, S K; Chang, S W; Tam, K S; Viseu, A

    2012-03-01

    Atmospheric aerosol over Macao was monitored by using a 355 nm Mie scattering lidar during the dust event on March 22nd, 2010. Vertical profiles of aerosol extinction coefficients were obtained and correlated with local PM10 concentration. The near-surface aerosol extinction coefficients have good agreement with PM10 concentration values. The aerosol extinction vertical profiles showed that there were distinct layers of dust aerosol concentration. The source and tracks of dust aerosol were analyzed by back-trajectory simulation. Observations showed that this lidar could run well even in dust storm episode, and it would help to further the study on aerosol properties over Macao. PMID:22582620

  7. Real-time detection method and system for identifying individual aerosol particles

    DOEpatents

    Gard, Eric E.; Coffee, Keith R.; Frank, Matthias; Tobias, Herbert J.; Fergenson, David P.; Madden, Norm; Riot, Vincent J.; Steele, Paul T.; Woods, Bruce W.

    2007-08-21

    An improved method and system of identifying individual aerosol particles in real time. Sample aerosol particles are collimated, tracked, and screened to determine which ones qualify for mass spectrometric analysis based on predetermined qualification or selection criteria. Screening techniques include one or more of determining particle size, shape, symmetry, and fluorescence. Only qualifying particles passing all screening criteria are subject to desorption/ionization and single particle mass spectrometry to produce corresponding test spectra, which is used to determine the identities of each of the qualifying aerosol particles by comparing the test spectra against predetermined spectra for known particle types. In this manner, activation cycling of a particle ablation laser of a single particle mass spectrometer is reduced.

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

  9. Observations of Aerosol Optical Properties over 15 AERONET Sites in Southeast Asia

    NASA Astrophysics Data System (ADS)

    Chan, J. D.; Lagrosas, N.; Uy, S. N.; Holben, B. N.; Dorado, S.; Tobias, V., Jr.; Anh, N. X.; Po-Hsiung, L.; Janjai, S.; Salinas Cortijo, S. V.; Liew, S. C.; Lim, H. S.; Lestari, P.

    2014-12-01

    Mean column-integrated optical properties from ground sun photometers of the Aerosol Robotic Network (AERONET) are studied to provide an overview of the characteristics of aerosols over the region as part of the 7 Southeast Asian Studies (7-SEAS) mission. The 15 AERONET sites with the most available level 2 data products are selected from Thailand (Chiang Mai, Mukdahan, Songkhla and Silpakorn University), Malaysia (University Sains Malaysia), Laos (Vientiane), Vietnam (Bac Giang, Bac Lieu and Nha Trang), Taiwan (National Cheng Kung University and Central Weather Bureau Taipei), Singapore, Indonesia (Bandung) and the Philippines (Manila Observatory and Notre Dame of Marbel University). For all 15 sites, high angstrom exponent values (α>1) have been observed. Chiang Mai and USM have the highest mean Angstrom exponent indicating the dominance of fine particles that can be ascribed to biomass burning and urbanization. Sites with the lowest Angstrom exponent values include Bac Lieu (α=1.047) and Manila Observatory (α=1.021). From the average lognormal size distribution curves, Songkhla and NDMU show the smallest annual variation in the fine mode region, indicating the observed fine aerosols are local to the sites. The rest of the sites show high variation which could be due to large scale forcings (e.g., monsoons and biomass burnings) that affect aerosol properties in these sites. Both high and low single scattering albedo at 440 nm (ω0440) values are found in sites located in major urban areas. Silpakorn University, Manila Observatory and Vientiane have all mean ω0440 < 0.90. Singapore and CWB Taipei have ω0440 > 0.94. The discrepancy in ω0 suggests different types of major emission sources present in urban areas. The absorptivity of urban aerosols can vary depending on the strength of traffic emissions, types of fuel combusted and automobile engines used, and the effect of biomass burning aerosols during the dry season. High aerosol optical depth values (τa550

  10. Vertical profiling of aerosol particles and trace gases over the central Arctic Ocean during summer

    NASA Astrophysics Data System (ADS)

    Kupiszewski, P.; Leck, C.; Tjernström, M.; Sjogren, S.; Sedlar, J.; Graus, M.; Müller, M.; Brooks, B.; Swietlicki, E.; Norris, S.; Hansel, A.

    2013-12-01

    Unique measurements of vertical size-resolved aerosol particle concentrations, trace gas concentrations and meteorological data were obtained during the Arctic Summer Cloud Ocean Study (ASCOS, www.ascos.se), an International Polar Year project aimed at establishing the processes responsible for formation and evolution of low-level clouds over the high Arctic summer pack ice. The experiment was conducted from on board the Swedish icebreaker Oden, and provided both ship- and helicopter-based measurements. This study focuses on the vertical helicopter profiles and onboard measurements obtained during a three-week period when Oden was anchored to a drifting ice floe, and sheds light on the characteristics of Arctic aerosol particles and their distribution throughout the lower atmosphere. Distinct differences in aerosol particle characteristics within defined atmospheric layers are identified. Within the lowermost couple hundred metres, transport from the marginal ice zone (MIZ), condensational growth and cloud processing develop the aerosol population. During two of the four representative periods defined in this study, such influence is shown. At altitudes above about 1 km, long-range transport occurs frequently. However, only infrequently does large-scale subsidence descend such air masses to become entrained into the mixed layer in the high Arctic, and therefore long-range transport plumes are unlikely to directly influence low-level stratiform cloud formation. Nonetheless, such plumes can influence the radiative balance of the planetary boundary layer (PBL) by influencing formation and evolution of higher clouds, as well as through precipitation transport of particles downwards. New particle formation was occasionally observed, particularly in the near-surface layer. We hypothesize that the origin of these ultrafine particles could be in biological processes, both primary and secondary, within the open leads between

  11. Vertical profiling of aerosol particles and trace gases over the central Arctic Ocean during summer

    NASA Astrophysics Data System (ADS)

    Kupiszewski, P.; Leck, C.; Tjernström, M.; Sjogren, S.; Sedlar, J.; Graus, M.; Müller, M.; Brooks, B.; Swietlicki, E.; Norris, S.; Hansel, A.

    2013-04-01

    Unique measurements of vertical size resolved aerosol particle concentrations, trace gas concentrations and meteorological data were obtained during the Arctic Summer Cloud Ocean Study (ASCOS, http://www.ascos.se), an International Polar Year project aimed at establishing the processes responsible for formation and evolution of low-level clouds over the high Arctic summer pack ice. The experiment was conducted from onboard the Swedish icebreaker Oden, and provided both ship- and helicopter-based measurements. This study focuses on the vertical helicopter profiles and onboard measurements obtained during a three-week period when Oden was anchored to a drifting ice floe, and sheds light on the characteristics of Arctic aerosol particles and their distribution throughout the lower atmosphere. Distinct differences in aerosol particle characteristics within defined atmospheric layers are identified. Near the surface (lowermost couple hundred meters), transport from the marginal ice zone (MIZ), if sufficiently short (less than ca. 2 days), condensational growth and cloud-processing develop the aerosol population. During two of the four representative periods defined in this study, such influence is shown. At altitudes above about 1 km, long-range transport occurs frequently. However, only infrequently does large-scale subsidence descend such air masses to become entrained into the mixed layer in the high Arctic, and therefore they are unlikely to directly influence low-level stratiform cloud formation. Nonetheless, long-range transport plumes can influence the radiative balance of the PBL by influencing formation and evolution of higher clouds, as well as through precipitation transport of particles downwards. New particle formation was occasionally observed, particularly in the near-surface layer. We hypothesize that the origin of these ultrafine particles can be from biological processes, both primary and secondary

  12. Modeling global impacts of heterogeneous loss of HO2 on cloud droplets, ice particles and aerosols

    NASA Astrophysics Data System (ADS)

    Huijnen, V.; Williams, J. E.; Flemming, J.

    2014-03-01

    The abundance and spatial variability of the hydroperoxyl radical (HO2) in the troposphere strongly affects atmospheric composition through tropospheric ozone production and associated HOx chemistry. One of the largest uncertainties in the chemical HO2 budget is its heterogeneous loss on the surface of cloud droplets, ice particles and aerosols. We quantify the importance of the heterogeneous HO2 loss at global scale using the latest recommendations on the scavenging efficiency on various surfaces. For this we included the simultaneous loss on cloud droplets and ice particles as well as aerosol in the Composition-Integrated Forecast System (C-IFS). We show that cloud surface area density (SAD) is typically an order of magnitude larger than aerosol SAD, using assimilated satellite retrievals to constrain both meteorology and global aerosol distributions. Depending on the assumed uptake coefficients, loss on liquid water droplets and ice particles accounts for ∼53-70% of the total heterogeneous loss of HO2, due to the ubiquitous presence of cloud droplets. This indicates that HO2 uptake on cloud should be included in chemistry transport models that already include uptake on aerosol. Our simulations suggest that the zonal mean mixing ratios of HO2 are reduced by ∼25% in the tropics and up to ∼50% elsewhere. The subsequent decrease in oxidative capacity leads to a global increase of the tropospheric carbon monoxide (CO) burden of up to 7%, and an increase in the ozone tropospheric lifetime of ∼6%. This increase results in an improvement in the global distribution when compared against CO surface observations over the Northern Hemisphere, although it does not fully resolve the wintertime bias in the C-IFS. There is a simultaneous increase in the high bias in C-IFS for tropospheric CO over the Southern Hemisphere, which constrains on the assumptions regarding HO2 uptake on a global scale. We show that enhanced HO2 uptake on aerosol types associated with

  13. 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.

  14. The Global Aerosol Synthesis and Science Project (GASSP): Using a Comprehensive Synthesis of Aerosol Observations and Statistical Modelling to Constrain Model Uncertainty

    NASA Astrophysics Data System (ADS)

    Reddington, C.; Lee, L.; Carslaw, K. S.; Liu, D.; Allan, J. D.; Coe, H.; Pringle, K.; Stier, P.; Partridge, D.; Schutgens, N.

    2014-12-01

    Over the past few decades there has been enormous investment in atmospheric aerosol measurements across the globe. However, ultimately only a small fraction of these measurements are used to test and improve models. GASSP aims to bring together as much aerosol measurement data as possible in combination with a novel application of statistical methods to test and improve atmospheric model processes and improve our understanding of global aerosol and climate. Presently, we have synthesised a vast array of diverse aerosol measurements from aircraft, ground stations and ships, combining campaign and long-term measurements conducted over the past two decades. These data include in-situ measurements of cloud condensation nuclei and aerosol particle number concentrations, sizes and chemical composition. By combining different aerosol measurements we can ensure that the model skill is consistent across a range of aerosol properties in a range of environments. We will present spatial maps and time series of these data, identifying key regions where gaps currently exist in the dataset and where future contribution from the measurement community will be most crucial. We have also performed a sensitivity analysis of the output from a global aerosol model, which has identified the important sources of parameter uncertainty in all model grid cells throughout a single year. Cluster analysis of this data shows which model uncertainties can be constrained by observations in any particular global region during the year. Similarities and distinctions between clusters allows us to identify how observations made around the globe have the potential to constrain the global aerosol model and identify which model uncertainties will remain irreducible with the current suite of observations. As a first step we have used synthetic observations to constrain the model uncertainties and quantify the potential of real observations for model constraint. We then use these results to target real

  15. 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...

  16. Structure and dissolution of L-leucine-coated salbutamol sulphate aerosol particles.

    PubMed

    Raula, Janne; Seppälä, Jukka; Malm, Jari; Karppinen, Maarit; Kauppinen, Esko I

    2012-06-01

    L-Leucine formed different crystalline coatings on salbutamol sulphate aerosol particles depending on the saturation conditions of L-leucine. The work emphasizes a careful characterization of powders where structural compartments such as crystal size and particle coating may affect the performance of drug when administered. The sublimation of L-leucine from the aerosol particles took place 90°C lower temperature than the bulk L-leucine which was attributed to result from the sublimation of L-leucine from nano-sized crystalline domains. The dissolution slowed down and initial dissolution rate decreased with increasing L-leucine content. Decreasing crystalline domains to nano-scale improve heat and mass transfer which was observed as the lowered decomposition temperature of the drug salbutamol sulphate and the sublimation temperature of surface material L-leucine as well as the altered dissolution characteristics of the drug. The structure of the coated drug particles was studied by means of thermal analysis techniques (DSC and TG), and the dissolution of salbutamol sulphate was studied as an on-line measurement in a diffusion cell. PMID:22562614

  17. Single particle characterization of biomass burning organic aerosol (BBOA): evidence for non-uniform mixing of high molecular weight organics and potassium

    NASA Astrophysics Data System (ADS)

    Lee, A. K. Y.; Willis, M. D.; Healy, R. M.; Wang, J. M.; Jeong, C.-H.; Wenger, J. C.; Evans, G. J.; Abbatt, J. P. D.

    2015-11-01

    Biomass burning is a major source of black carbon (BC) and primary organic aerosol globally. In particular, biomass burning organic aerosol (BBOA) is strongly associated with atmospheric brown carbon (BrC) that absorbs near ultraviolet and visible light, resulting in significant impacts on regional visibility degradation and radiative forcing. The mixing state of BBOA can play a critical role in the prediction of aerosol optical properties. In this work, single particle measurements from a soot-particle aerosol mass spectrometer coupled with a light scattering module (LS-SP-AMS) were performed to examine the mixing state of BBOA, refractory black carbon (rBC) and potassium (K+, a tracer for biomass burning aerosol) in an air mass influenced by aged biomass burning. Cluster analysis of single particle measurements identified five BBOA-related particle types. rBC accounted for 3-14 w.t. % of these particle types on average. Only one particle type exhibited a strong ion signal for K+, with mass spectra characterized by low molecular weight organic species. The remaining four particle types were classified based on the apparent molecular weight of the BBOA constituents. Two particle types were associated with low potassium content and significant amounts of high molecular weight (HMW) organic compounds. Our observations indicate non-uniform mixing of particles within a biomass burning plume in terms of molecular weight and illustrate that HMW BBOA can be a key contributor to low-volatility BrC observed in BBOA particles.

  18. Chemical composition and sources of coastal marine aerosol particles during the 2008 VOCALS-REx campaign

    SciTech Connect

    Lee, Y. -N.; Springston, S.; Jayne, J.; Wang, J.; Hubbe, J.; Senum, G.; Kleinman, L.; Daum, P. H.

    2014-01-01

    The chemical composition of aerosol particles (Dp ≤ 1.5 μm) was measured over the southeast Pacific Ocean during the VAMOS (Variability of the American Monsoon Systems) Ocean-Cloud-Atmosphere-Land Study Regional Experiment (VOCALS-Rex) between 16 October and 15 November 2008 using the US Department of Energy (DOE) G-1 aircraft. The objective of these flights was to gain an understanding of the sources and evolution of these aerosols, and of how they interact with the marine stratus cloud layer that prevails in this region of the globe. Our measurements showed that the marine boundary layer (MBL) aerosol mass was dominated by non-sea-salt SO42−, followed by Na+, Cl, Org (total organics), NH4+, and NO3, in decreasing order of importance; CH3SO3 (MSA), Ca2+, and K+ rarely exceeded their limits of detection. Aerosols were strongly acidic with a NH4+ to SO42− equivalents ratio typically < 0.3. Sea-salt aerosol (SSA) particles, represented by NaCl, exhibited Cl deficits caused by both HNO3 and H2SO4, but for the most part were externally mixed with particles, mainly SO42−. SSA contributed only a small fraction of the total accumulation mode particle number concentration. It was inferred that all aerosol species (except SSA) were of predominantly continental origin because of their strong land-to-sea concentration gradient. Comparison of relative changes in median values suggests that (1) an oceanic source of NH3 is present between 72° W and 76° W, (2) additional organic aerosols from biomass burns or biogenic precursors were emitted from coastal regions south of 31° S, with possible cloud processing, and (3) free tropospheric (FT) contributions to MBL gas and aerosol

  19. Observations of the first aerosol indirect effect in shallow cumuli

    SciTech Connect

    Berg, Larry K.; Berkowitz, Carl M.; Barnard, James C.; Senum, Gunar; Springston, Stephen R.

    2011-02-08

    Data from the Cumulus Humilis Aerosol Processing Study (CHAPS) are used to estimate the impact of both aerosol indirect effects and cloud dynamics on the microphysical and optical properties of shallow cumuli observed in the vicinity of Oklahoma City, Oklahoma. Not surprisingly, we find that the amount of light scattered by the clouds is dominated by their liquid water content (LWC), which in turn is driven by cloud dynamics. However, removing the effect of cloud dynamics by examining the scattering normalized by LWC shows a strong sensitivity of scattering to pollutant loading. These results suggest that even moderately sized cities, like Oklahoma City, can have a measureable impact on the optical properties of shallow cumuli.

  20. Studying seasonal variations in carbonaceous aerosol particles in the atmosphere over central Siberia

    NASA Astrophysics Data System (ADS)

    Mikhailov, E. F.; Mironova, S. Yu.; Makarova, M. V.; Vlasenko, S. S.; Ryshkevich, T. I.; Panov, A. V.; Andreae, M. O.

    2015-07-01

    The results of 2-year (2010-2012) measurements of the concentrations of organic carbon (OC) and elemental carbon (EC), which were taken at the Zotino Tall Tower Observatory (ZOTTO) Siberian background station (61° N, 89° E), are given. Despite the fact that this station is located far from populated areas and industrial zones, the concentrations of OC and EC in the atmosphere over boreal forests in central Siberia significantly exceed their background values. In winter and fall, high concentrations of atmospheric carbonaceous aerosol particles are caused by the long-range transport (~1000 km) of air masses that accumulate pollutants from large cities located in both southern and southwestern regions of Siberia. In spring and summer, the pollution level is also high due to regional forest fires and agricultural burning in the steppe zone of western Siberia in the Russian-Kazakh border region. Background concentrations of carbonaceous aerosol particles were observed within relatively short time intervals whose total duration was no more than 20% of the entire observation period. In summer, variations in the background concentrations of OC closely correlated with air temperature, which implies that the biogenic sources of organic-particle formation are dominating.

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

    NASA Astrophysics Data System (ADS)

    Jensen, Jorgen

    2013-04-01

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

  2. Observation of Asian Mineral Dust Particles in Japan by a Single-Particle Mass Spectrometer

    NASA Astrophysics Data System (ADS)

    Matsumoto, J.; Takahashi, K.; Matsumi, Y.; Sugimoto, N.; Matsui, I.; Shimizu, A.

    2005-12-01

    The Asian mineral dust (Kosa) particles, emitted from the desert area of inland China, are characteristic of East Asian aerosols. The Kosa particles are important as regional carriers of various materials, especially in spring when the stormy dusts are transported to Japan and Pacific Ocean. In this study, the chemical mixing state of each atmospheric aerosol was measured individually by a laser-based time-of-flight mass spectrometer (TOFMS) to discuss chemical changes of Kosa particles during the transport. Observation was conducted at Tsukuba (36.05°N, 140.12°E) in April and May 2004. The LIDAR measurement was also carried out to determine the Kosa events. To classify the source of the air mass, the NOAA-HYSPLIT backward trajectory was applied. For the TOFMS instrument, particles with μm and sub-μm diameters were detected. The polarity of ion detection was altered every minute. During 30 days, the numbers of logged mass spectra (MS) were 5993 and 4382 for positive and negative ions, respectively. When the MS of ambient aerosols were compared with that of the standard Kosa sample, sulfate- and nitrate-mixed Kosa particles were found. To explore the mixing state of particles further, classification of the particles by the ART-2a algorithm was adopted. NO2-, NO3-, HSO4-, SiO2-, SiO3-, Cl- and NaCl2- were focused. Finally, particles were classified to 4 categories as A: sulfate and sulfate-rich mineral; B: sulfate-poor mineral; C: sea salt; D: unidentified. The relative fractions of A were 30 % and 1 % for a Kosa event and a maritime air mass, respectively. Note that the air mass for Kosa event case passed over the coast region of China, where SOx emission was intensive. It was reasonable that sulfate was internally mixed with Kosa particles and transported to Japan. Consequently, it was confirmed experimentally that Kosa particles are important as carriers of pollutants in the rim region of Pacific Ocean. Comparison with the observation in 2005 is also shown.

  3. Impacts of aerosol particles on the microphysical and radiative properties of stratocumulus clouds over the Southeast Pacific ocean

    NASA Astrophysics Data System (ADS)

    Twohy, C. H.; Anderson, J. R.; To