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Sample records for aerosol hygroscopic growth

  1. 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 0.030µmgrowth 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.

  2. Water Uptake and Hygroscopic Growth of Organosulfate Aerosol.

    PubMed

    Estillore, Armando D; Hettiyadura, Anusha P S; Qin, Zhen; Leckrone, Erin; Wombacher, Becky; Humphry, Tim; Stone, Elizabeth A; Grassian, Vicki H

    2016-04-19

    Organosulfates (OS) are important components of secondary organic aerosol (SOA) that have been identified in numerous field studies. This class of compounds within SOA can potentially affect aerosol physicochemical properties such as hygroscopicity because of their polar and hydrophilic nature as well as their low volatility. Currently, there is a dearth of information on how aerosol particles that contain OS interact with water vapor in the atmosphere. Herein we report a laboratory investigation on the hygroscopic properties of a structurally diverse set of OS salts at varying relative humidity (RH) using a Hygroscopicity-Tandem Differential Mobility Analyzer (H-TDMA). The OS studied include the potassium salts of glycolic acid sulfate, hydroxyacetone sulfate, 4-hydroxy-2,3-epoxybutane sulfate, and 2-butenediol sulfate and the sodium salts of benzyl sulfate, methyl sulfate, ethyl sulfate, and propyl sulfate. In addition, mixtures of OS and sodium chloride were also studied. The results showed gradual deliquescence of these aerosol particles characterized by continuous uptake and evaporation of water in both hydration and dehydration processes for the OS, while the mixture showed prompt deliquescence and effloresce transitions, albeit at a lower relative humidity relative to pure sodium chloride. Hygroscopic growth of these OS at 85% RH were also fit to parameterized functional forms. This new information provided here has important implications about the atmospheric lifetime, light scattering properties, and the role of OS in cloud formation. Moreover, results of these studies can ultimately serve as a basis for the development and evaluation of thermodynamic models for these compounds in order to consider their impact on the atmosphere. PMID:26967467

  3. Water Activity Limits the Hygroscopic Growth Factor of Organic Aerosols

    NASA Astrophysics Data System (ADS)

    Rodriguez, L. I.; Cabrera, J. A.; Golden, D.; Tabazadeh, A.

    2007-12-01

    In this work we study the hygroscopic behavior of organic aerosols, which has important implications for Earth's climate. The hygroscopic growth factor (HGF) is defined as the ratio of the diameter of a spherical particle when it is exposed to dry conditions to that at humid conditions. We present a new formulation to express the HGF of an aerosol particle as a function of water activity (aw) in the aqueous phase. This new formulation matches reported HGFs for common inorganic salts and water-miscible organic particles that are known to deliquesce into aqueous drops at high relative humidities (RH). Many studies use tandem differential mobility analyzers (TDMA) to determine the HGF of organic aerosols. For example, Brooks et al. used a TDMA to measure a HGF of 1.2 for 2 μm phthalic acid (PA) particles at 90% RH (aw= 0.9). However, water activity limits the growth of a particle that can be attributed to water uptake. We have assembled a vapor pressure apparatus to measure aw of aqueous solutions at room temperature. Measured water activities for PA, used in our growth formulation, yield a HGF of ~ 1.0005 for 2 μm PA particles at 90% RH. Comparing our results against Brooks et al. suggests that TDMA experiments may grossly overestimate the HGF of PA particles since water activity limits this growth to below 1.0005. Alternatively, we suggest that the adsorption of a negligible mass of water by a highly porous PA particle can lead to an apparent growth in particle size by changing its morphology. Other studies also use TDMAs to measure HGFs of secondary organic aerosols (SOAs). HGFs reported for SOAs are very similar to PA, suggesting that the observed growth may be due to morphological changes in particle size rather than water uptake as commonly assumed. We built a smog chamber where an organic precursor, such as d-limonene, reacts with nitrogen oxides under UV radiation to produce SOAs. We compare the HGFs for SOAs obtained with our method to those obtained with

  4. Hygroscopic growth of urban aerosol particles during the 2009 Mirage-Shanghai Campaign

    NASA Astrophysics Data System (ADS)

    Ye, Xingnan; Tang, Chen; Yin, Zi; Chen, Jianmin; Ma, Zhen; Kong, Lingdong; Yang, Xin; Gao, Wei; Geng, Fuhai

    2013-01-01

    The hygroscopic properties of submicrometer urban aerosol particles were studied during the 2009 Mirage-Shanghai Campaign. The urban aerosols were composed of more-hygroscopic and nearly-hydrophobic particles, together with a trace of less-hygroscopic particles. The mean hygroscopicity parameter κ of the more-hygroscopic mode varied in the range of 0.27-0.39 depending on particle size. The relative abundance of the more-hygroscopic particles at any size was ca. 70%, slightly increasing with particle size. The number fraction of the nearly-hydrophobic particles fluctuated between 0.1 and 0.4 daily, in accordance with traffic emissions and atmospheric diffusion. The results from relative humidity dependence on hygroscopic growth and chemical analysis of fine particles indicated that particulate nitrate formation through the homogenous gas-phase reaction was suppressed under ammonia-deficient atmosphere in summer whereas the equilibrium was broken by more available NH3 during adverse meteorological conditions.

  5. The contribution of aerosol hygroscopic growth to the modeled aerosol radiative effect

    NASA Astrophysics Data System (ADS)

    Kokkola, Harri; Kühn, Thomas; Kirkevåg, Alf; Romakkaniemi, Sami; Arola, Antti

    2016-04-01

    The hygroscopic growth of atmospheric aerosols can have a significant effect on the direct radiative effect of atmospheric aerosol. However, there are significant uncertainties concerning how much of the radiative forcing is due to different chemical compounds, especially water. For example, modeled optical depth of water in global aerosol-climate models varies by more than a factor of two. These differences can be attributed to differences in modeled 1) hygroscopicity, 2) ambient relative humidity, and/or 3) aerosol size distribution. In this study, we investigate which of these above-mentioned factors cause the largest variability in the modeled optical depth of water. In order to do this, we have developed a tool that calculates aerosol extinction using interchangeable global 3D data of aerosol composition, relative humidity, and aerosol size distribution fields. This data is obtained from models that have taken part in the open international initiative AeroCom (Aerosol Comparisons between Observations and Models). In addition, we use global 3D data for relative humidity from the Atmospheric Infrared Sounder (AIRS) flying on board NASA's Aqua satellite and the National Centers for Environmental Prediction (NCEP) reanalysis data. These observations are used to evaluate the modeled relative humidity fields. In the first stage of the study, we made a detailed investigation using the aerosol-chemistry-climate model ECHAM-HAMMOZ in which most of the aerosol optical depth is caused by water. Our results show that the model significantly overestimates the relative humidity over the oceans while over land, the overestimation is lower or it is underestimated. Since this overestimation occurs over the oceans, the water optical depth is amplified as the hygroscopic growth is very sensitive to changes in high relative humidities. Over land, error in modeled relative humidity is unlikely to cause significant errors in water optical depth as relative humidities are generally

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

    PubMed

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

    2015-05-14

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

  7. INFLUENCE OF HYGROSCOPIC GROWTH UPON THE DEPOSITION OF BRONCHODILATOR AEROSOLS IN UPPER HUMAN AIRWAYS

    EPA Science Inventory

    The influence of hygroscopic growth upon the behavior of two bronchodilator drugs in upper airways is studied with an aerosol deposition model. The latter accounts for laryngeal jet impaction and turbulent flow instabilities caused by the larynx in computing particle deposition e...

  8. Aerosol optical properties in the southeastern United States in summer - Part 1: Hygroscopic growth

    NASA Astrophysics Data System (ADS)

    Brock, Charles A.; Wagner, Nicholas L.; Anderson, Bruce E.; Attwood, Alexis R.; Beyersdorf, Andreas; Campuzano-Jost, Pedro; Carlton, Annmarie G.; Day, Douglas A.; Diskin, Glenn S.; Gordon, Timothy D.; Jimenez, Jose L.; Lack, Daniel A.; Liao, Jin; Markovic, Milos Z.; Middlebrook, Ann M.; Ng, Nga L.; Perring, Anne E.; Richardson, Matthews S.; Schwarz, Joshua P.; Washenfelder, Rebecca A.; Welti, Andre; Xu, Lu; Ziemba, Luke D.; Murphy, Daniel M.

    2016-04-01

    Aircraft observations of meteorological, trace gas, and aerosol properties were made during May-September 2013 in the southeastern United States (US) under fair-weather, afternoon conditions with well-defined planetary boundary layer structure. Optical extinction at 532 nm was directly measured at relative humidities (RHs) of ˜ 15, ˜ 70, and ˜ 90 % and compared with extinction calculated from measurements of aerosol composition and size distribution using the κ-Köhler approximation for hygroscopic growth. The calculated enhancement in hydrated aerosol extinction with relative humidity, f(RH), calculated by this method agreed well with the observed f(RH) at ˜ 90 % RH. The dominance of organic aerosol, which comprised 65 ± 10 % of particulate matter with aerodynamic diameter < 1 µm in the planetary boundary layer, resulted in relatively low f(RH) values of 1.43 ± 0.67 at 70 % RH and 2.28 ± 1.05 at 90 % RH. The subsaturated κ-Köhler hygroscopicity parameter κ for the organic fraction of the aerosol must have been < 0.10 to be consistent with 75 % of the observations within uncertainties, with a best estimate of κ = 0.05. This subsaturated κ value for the organic aerosol in the southeastern US is broadly consistent with field studies in rural environments. A new, physically based, single-parameter representation was developed that better described f(RH) than did the widely used gamma power-law approximation.

  9. Reformulating atmospheric aerosol thermodynamics and hygroscopic growth into fog, haze and clouds

    NASA Astrophysics Data System (ADS)

    Metzger, S.; Lelieveld, J.

    2007-06-01

    Modeling atmospheric aerosol and cloud microphysics is rather complex, even if chemical and thermodynamical equilibrium is assumed. We show, however, that the thermodynamics can be considerably simplified by reformulating equilibrium to consistently include water, and transform laboratory-based concepts to atmospheric conditions. We generalize the thermodynamic principles that explain hydration and osmosis - merely based on solute solubilities - to explicitly account for the water mass consumed by hydration. As a result, in chemical and thermodynamical equilibrium the relative humidity (RH) suffices to determine the saturation molality, including solute and solvent activities (and activity coefficients), since the water content is fixed by RH for a given aerosol concentration and type. As a consequence, gas/liquid/solid aerosol equilibrium partitioning can be solved analytically and non-iteratively. Our new concept enables an efficient and accurate calculation of the aerosol water mass and directly links the aerosol hygroscopic growth to fog, haze and cloud formation. We apply our new concept in the 3rd Equilibrium Simplified Aerosol Model (EQSAM3) for use in regional and global chemistry-transport and climate models. Its input is limited to the species' solubilities from which a newly introduced stoichiometric coefficient for water is derived. Analogously, we introduce effective stoichiometric coefficients for the solutes to account for complete or incomplete dissociation. We show that these coefficients can be assumed constant over the entire activity range and calculated for various inorganic, organic and non-electrolyte compounds, including alcohols, sugars and dissolved gases. EQSAM3 calculates the aerosol composition and gas/liquid/solid partitioning of mixed inorganic/organic multicomponent solutions and the associated water uptake for almost 100 major compounds. It explicitly accounts for particle hygroscopic growth by computing aerosol properties such as

  10. HYGROSCOPIC GROWTH: ITS EFFECT ON AEROSOL THERAPY AND INHALATION TOXICOLOGY

    EPA Science Inventory

    The success of an aerosol therapy protocol is contingent upon a proper quantity of drug being delivered to an appropriate site within the respiratory tract to elicit a therapeutic effect. Likewise, an accurate risk assessment of the threat to human health presented by airborne po...

  11. Aerosol mixing state, hygroscopic growth and cloud activation efficiency during MIRAGE 2006

    NASA Astrophysics Data System (ADS)

    Lance, S.; Raatikainen, T.; Onasch, T. B.; Worsnop, D. R.; Yu, X.-Y.; Alexander, M. L.; Stolzenburg, M. R.; McMurry, P. H.; Smith, J. N.; Nenes, A.

    2013-05-01

    Observations of aerosol hygroscopic growth and CCN activation spectra for submicron particles are reported for the T1 ground site outside of Mexico City during the MIRAGE 2006 campaign. κ-Köhler theory is used to evaluate the characteristic hygroscopicity parameter, κ*, for the CCN active aerosol population using both size-resolved HTMDA and size-resolved CCNc measurements. Organic mass fractions (forg) are evaluated from size-resolved aerosol mass spectrometer (AMS) measurements, from which predictions of the hygroscopicity parameter are compared against κ*. Strong diurnal changes in aerosol water uptake parameters and aerosol composition are observed. We find that new particle formation (NPF) events are correlated with an increased κ* and CCN-active fraction during the daytime, with greater impact on smaller particles. During NPF events, the number concentration of 40 nm particles acting as CCN at 0.51% ± 0.06% supersaturation can surpass by more than a factor of two the corresponding concentrations of 100 nm particles. We also find that at 06:00-08:00 LT throughout the campaign, fresh traffic emissions result in substantial changes to the chemical distribution of the aerosol, with on average 65% externally mixed fraction for 40 nm particles and 30% externally mixed fraction for 100 nm particles, whereas at midday nearly all particles of both sizes can be described as "internally mixed". Average activation spectra and growth factor distributions are analyzed for different time periods characterizing the daytime (with and without NPF events), the early morning "rush hour" and the entire campaign. We show that κ* derived from CCNc measurements decreases as a function of size during all time periods, while the CCN-active fraction increases as a function of size. Size-resolved AMS measurements do not predict the observed trend for κ* versus particle size, which can be attributed to unresolved mixing state and the presence of refractory material not measured

  12. Hygroscopic growth and activation of HULIS particles: experimental data and a new iterative parameterization scheme for complex aerosol particles

    NASA Astrophysics Data System (ADS)

    Ziese, M.; Wex, H.; Nilsson, E.; Salma, I.; Ocskay, R.; Hennig, T.; Massling, A.; Stratmann, F.

    2007-09-01

    The hygroscopic growth and activation of two HULIS and one Aerosol-Water-Extract sample, prepared from urban-type aerosol, were investigated. All samples were extracted from filters, redissolved in water and atomized for the investigations presented here. The hygroscopic growth measurements were done using LACIS (Leipzig Aerosol Cloud Interaction Simulator) together with a HH-TDMA (High Humidity Tandem Differential Mobility Analyzer). Hygroscopic growth was determined for relative humidities up to 99.75%. The critical diameters for activation were measured using LACIS for supersaturations between 2 and 10 per mill. All three samples showed a similar hygroscopic growth behaviour, and the two HULIS samples also were similar in their activation behavior, while the Aerosol-Water-Extract turned out to be more CCN active than the HULIS samples. The experimental data was used to derive parameterizations for the hygroscopic growth and activation of HULIS particles. The concept of ρion (Wex et al., 2007a) and the Szyszkowski-equation (Szyszkowski, 1908; Facchini et al., 1999) were used for parameterizing the Raoult and the Kelvin (surface tension) terms of the Köhler equation, respectively. This concept proved to be very successful for the HULIS samples in the saturation range from relative humidities larger than 98% up to activation. However it failed for the Aerosol-Water extract.

  13. Variations in hygroscopic growth of sub- and super-micron sea spray aerosols during a phytoplankton bloom

    NASA Astrophysics Data System (ADS)

    Forestieri, S.; Jayarathne, T. S.; Stone, E. A.; Laskina, O.; Grassian, V. H.; Lee, C.; Sultana, C. M.; Moore, K.; Cornwell, G.; Novak, G.; Bertram, T. H.; Prather, K. A.; Cappa, C. D.

    2014-12-01

    Marine sea spray aerosols (SSA) make up an important portion of natural aerosols (prior to anthropogenic influence) and are therefore important in establishing the baseline for anthropogenic aerosol climate impacts. One way aerosols impact climate is by scattering solar radiation, and how much light is scattered depends upon the size of aerosols. Aerosols grow larger via water uptake and thus scatter more light at elevated relative humidities. This growth depends on composition. SSA can become enriched in organics during phytoplankton blooms, becoming less salty and therefore less hygroscopic. Aerosol hygroscopicity of SSA sampled during an in-lab phytoplankton bloom were measured during the CAICE-IMPACTS 2014 study. SSA were generated via breaking waves in an enclosed 33 m wave channel filled with natural seawater. Aerosol hygroscopicity was characterized by measuring light extinction at 532 nm of dry aerosols and of aerosols humidified to 85% relative humidity using a Cavity Ringdown Spectrometer. These optical growth factors (humidified extinction/dry extinction) were converted to physical growth factors using Mie Theory calculations and aerosol size distributions measured with a scanning electrical mobility spectrometer (SEMS) and an aerodynamic particle sizer (APS). Growth factors for super- and sub-micron SSA were quantified separately through the use of a PM2.5 cyclone or PM1 impactor. The observed SSA growth factors will be linked to SSA and source water chemical composition determined by both offline and online analysis of samples. The SSA bulk growth factors will also be compared with concurrent measurements of the efficiency with which SSA act as cloud condensation nuclei. Observed SSA growth factors will also be compared to offline hygroscopic growth measurements.

  14. Reformulating atmospheric aerosol thermodynamics and hygroscopic growth into haze and clouds

    NASA Astrophysics Data System (ADS)

    Metzger, S.; Lelieveld, J.

    2007-01-01

    Modeling atmospheric aerosol and cloud microphysics is rather complex, even if chemical and thermodynamical equilibrium is assumed. We show, however, that the thermodynamics can be considerably simplified by reformulating equilibrium to include water, and transform laboratory-based concepts to atmospheric conditions. We generalize the thermodynamic principles that explain hydration and osmosis - merely based on solute solubilities. In chemical and thermodynamical equilibrium the relative humidity (RH) determines the saturation molality, including solute and solvent activities (and activity coefficients), since the water content is fixed by RH for a given aerosol concentration and type. As a consequence, gas/liquid/solid aerosol equilibrium partitioning can be solved analytically and non-iteratively. Our new concept enables an efficient and accurate calculation of the aerosol water mass and to directly link the aerosol hygroscopic growth to haze and cloud formation. We apply our new concept in the 3rd Equilibrium Simplified Aerosol Model (EQSAM3). Its input is limited to the species' solubilities from which a newly introduced stoichiometric coefficient for water is derived. Analogously, we introduce effective stochiometric coefficients for the solutes to account for complete or incomplete dissociation. We show that these coefficients can be assumed constant over the entire activity range and calculated for various inorganic, organic and non-electrolyte compounds, including alcohols, sugars and dissolved gases. EQSAM3 calculates the aerosol composition and gas/liquid/solid partitioning of mixed inorganic/organic multicomponent solutions and the associated water uptake for almost 100 major compounds. It explicitly accounts for particle hygroscopic growth by computing aerosol properties such as single solute molalities, molal based activities, including activity coefficients for volatile compounds, and deliquescence relative humidities of mixed solutes. Various

  15. CCN estimates from bulk hygroscopic growth factors of ambient aerosols during the pre-monsoon season over Central Nepal

    NASA Astrophysics Data System (ADS)

    Shrestha, Prabhakar; Barros, Ana P.; Khlystov, Andrei

    2013-03-01

    Aerosol size distribution (ambient and dried) and chemical composition were measured simultaneously using two Scanning Mobility Particle Sizers (SMPSs) and filters during the pre-monsoon season (April-June 2009) at two locations in Central Nepal: Dhulikhel, an urban site in the Kathmandu valley, and Besisahar, a rural village in the Marsyangdi valley. Diameter growth factors (DGF) were estimated using the larger mode (around 100 nm) of the aerosol size distributions. The measured DGF suggest that the aerosols were in metastable state below 80% RH owing to the strong diurnal cycle of relative humidity (RH) at Dhulikhel, while no discernible growth was observed for Besisahar. Assuming ideal behavior of water-soluble organic compounds and using their fraction as determined by water extraction of filters produced the best agreement for a two-component hygroscopic growth model with the observed DGFs. This finding together with the DGF and chemical composition data were used to determine the aerosol bulk hygroscopicity parameter, κ. The κ parameter suggests that aerosols in this region are less hygroscopic than aerosols reported in previous studies from other regions. The estimated κ and the vertically scaled aerosol size distribution were then used to estimate the CCN spectra. These are the first estimates of CCN spectra from ground-based observations for the Central Himalaya region.

  16. Accurate Measurements of Aerosol Hygroscopic Growth over a Wide Range in Relative Humidity.

    PubMed

    Rovelli, Grazia; Miles, Rachael E H; Reid, Jonathan P; Clegg, Simon L

    2016-06-30

    Using a comparative evaporation kinetics approach, we describe a new and accurate method for determining the equilibrium hygroscopic growth of aerosol droplets. The time-evolving size of an aqueous droplet, as it evaporates to a steady size and composition that is in equilibrium with the gas phase relative humidity, is used to determine the time-dependent mass flux of water, yielding information on the vapor pressure of water above the droplet surface at every instant in time. Accurate characterization of the gas phase relative humidity is provided from a control measurement of the evaporation profile of a droplet of know equilibrium properties, either a pure water droplet or a sodium chloride droplet. In combination, and by comparison with simulations that account for both the heat and mass transport governing the droplet evaporation kinetics, these measurements allow accurate retrieval of the equilibrium properties of the solution droplet (i.e., the variations with water activity in the mass fraction of solute, diameter growth factor, osmotic coefficient or number of water molecules per solute molecule). Hygroscopicity measurements can be made over a wide range in water activity (from >0.99 to, in principle, <0.05) on time scales of <10 s for droplets containing involatile or volatile solutes. The approach is benchmarked for binary and ternary inorganic solution aerosols with typical uncertainties in water activity of <±0.2% at water activities >0.9 and ∼±1% below 80% RH, and maximum uncertainties in diameter growth factor of ±0.7%. For all of the inorganic systems examined, the time-dependent data are consistent with large values of the mass accommodation (or evaporation) coefficient (>0.1). PMID:27285052

  17. Hygroscopic growth and activation of HULIS particles: experimental data and a new iterative parameterization scheme for complex aerosol particles

    NASA Astrophysics Data System (ADS)

    Ziese, M.; Wex, H.; Nilsson, E.; Salma, I.; Ocskay, R.; Hennig, T.; Massling, A.; Stratmann, F.

    2008-03-01

    The hygroscopic growth and activation of two HULIS (HUmic LIke Substance) and one Aerosol-Water-Extract sample, prepared from urban-type aerosol, were investigated. All samples were extracted from filters, redissolved in water and atomized for the investigations presented here. The hygroscopic growth measurements were done using LACIS (Leipzig Aerosol Cloud Interaction Simulator) together with a HH-TDMA (High Humidity Tandem Differential Mobility Analyzer). Hygroscopic growth was determined for relative humidities (RHs) up to 99.75%. The critical diameters for activation were measured for supersaturations between 0.2 and 1%. All three samples showed a similar hygroscopic growth behavior, and the two HULIS samples also were similar in their activation behavior, while the Aerosol-Water-Extract turned out to be more CCN active than the HULIS samples. The experimental data was used to derive parameterizations for the hygroscopic growth and activation of HULIS particles. The concept of ρion (Wex et al., 2007a) and the Szyszkowski-equation (Szyszkowski, 1908; Facchini, 1999) were used for parameterizing the Raoult and the Kelvin (surface tension) terms of the Köhler equation, respectively. This concept proved to be very successful for the HULIS samples in the saturation range from RHs larger than 98% up to activation. It was also shown to work well with data on HULIS taken from literature. Here, different atmospheric life-times and/or different sources for the different samples showed up in different coefficients for the parameterization. However, the parameterization did not work out well for the Aerosol-Water-Extract.

  18. Hygroscopic growth of urban aerosol particles in Beijing (China) during wintertime: a comparison of three experimental methods

    NASA Astrophysics Data System (ADS)

    Meier, J.; Wehner, B.; Massling, A.; Birmili, W.; Nowak, A.; Gnauk, T.; Brüggemann, E.; Herrmann, H.; Min, H.; Wiedensohler, A.

    2009-03-01

    This paper presents hygroscopicity measurements of aerosol particles in the urban atmosphere of Beijing carried out in January 2005. Therefore, three different methods were used: 1) Combining Humidifying Differential Mobility Particle Sizer (H-DMPS) and Twin Differential Mobility Particle Sizer (TDMPS) measurements; 2) Hygroscopicity Tandem Differential Mobility Analyzer (H-TDMA) technique; 3) Calculating hygroscopic growth factors on the basis of a solubility model quantified by Micro Orifice Uniform Deposit Impactor (MOUDI) samples. Particle number size distributions from H-DMPS and TDMPS were evaluated to derive size-resolved descriptive hygroscopic growth factors (DHGF) of 30-400 nm particles at relative humidities (RH) of 55%, 77% and 90%. The atmospheric particles in Beijing were rather hydrophobic, with a maximum growth factor in the accumulation mode around 1.40 (±0.03) at 90% RH. The descriptive hygroscopic growth factors decreased significantly towards the lower measurement limit (1.04 (±0.15) at Dp=30 nm). A good agreement was found between the DHGFs and the H-TDMA-derived hygroscopic growth factors in the accumulation mode (100-400 nm), the DHGFs underestimated the values from the H-TDMA in the Aitken mode (<100 nm) by up to 0.1 at 90% RH. The calculation of hygroscopic growth factors based on the measured chemical composition showed that different modes of combining the inorganic ions caused a variation in growth factor of 0.1 at 90% RH. The solubility model was able to reproduce the size-dependent trend in the growth factor found by the other methods. In two cases of ion-dominated aerosol, the composition-derived growth factors tended to agree (±0.05) or underestimate (up to 0.1) the values measured by the other two methods. In the case of the organic-dominated aerosol, the reverse was true, with an overestimation of up to 0.2. The results shed light on the real experimental and methodological uncertainties that are still connected with the

  19. Optical and Physicochemical Properties of Brown Carbon Aerosol: Light Scattering, FTIR Extinction Spectroscopy, and Hygroscopic Growth.

    PubMed

    Tang, Mingjin; Alexander, Jennifer M; Kwon, Deokhyeon; Estillore, Armando D; Laskina, Olga; Young, Mark A; Kleiber, Paul D; Grassian, Vicki H

    2016-06-23

    in the mid-IR range (800 to 7000 cm(-1)) also showed no significant changes in either the real or the imaginary parts of the refractive indices for brown carbon aerosol particles when compared to ammonium sulfate. Therefore, changes in the optical properties of ammonium sulfate in the mid-IR spectral range due to reaction with methylglyoxal appear to be insignificant. In addition to these measurements, we have characterized additional physicochemical properties of the brown carbon aerosol particles including hygroscopic growth using a tandem-differential mobility analyzer. Compared to ammonium sulfate, brown carbon aerosol particles are found to have lower deliquescence relative humidity (DRH), efflorescence relative humidity (ERH), and hygroscopic growth at the same relative humidities. Overall, our study provides new details of the optical and physicochemical properties of a class of secondary organic aerosol which may have important implications for atmospheric chemistry and climate. PMID:27253434

  20. 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.

  1. Cloud condensation nuclei activity, droplet growth kinetics, and hygroscopicity of biogenic and anthropogenic secondary organic aerosol (SOA)

    NASA Astrophysics Data System (ADS)

    Zhao, D. F.; Buchholz, A.; Kortner, B.; Schlag, P.; Rubach, F.; Fuchs, H.; Kiendler-Scharr, A.; Tillmann, R.; Wahner, A.; Watne, Å. K.; Hallquist, M.; Flores, J. M.; Rudich, Y.; Kristensen, K.; Hansen, A. M. K.; Glasius, M.; Kourtchev, I.; Kalberer, M.; Mentel, Th. F.

    2016-02-01

    Interaction of biogenic volatile organic compounds (VOCs) with Anthropogenic VOC (AVOC) affects the physicochemical properties of secondary organic aerosol (SOA). We investigated cloud droplet activation (CCN activity), droplet growth kinetics, and hygroscopicity of mixed anthropogenic and biogenic SOA (ABSOA) compared to pure biogenic SOA (BSOA) and pure anthropogenic SOA (ASOA). Selected monoterpenes and aromatics were used as representative precursors of BSOA and ASOA, respectively.

    We found that BSOA, ASOA, and ABSOA had similar CCN activity despite the higher oxygen to carbon ratio (O/C) of ASOA compared to BSOA and ABSOA. For individual reaction systems, CCN activity increased with the degree of oxidation. Yet, when considering all different types of SOA together, the hygroscopicity parameter, κCCN, did not correlate with O/C. Droplet growth kinetics of BSOA, ASOA, and ABSOA were comparable to that of (NH4)2SO4, which indicates that there was no delay in the water uptake for these SOA in supersaturated conditions.

    In contrast to CCN activity, the hygroscopicity parameter from a hygroscopic tandem differential mobility analyzer (HTDMA) measurement, κHTDMA, of ASOA was distinctively higher (0.09-0.10) than that of BSOA (0.03-0.06), which was attributed to the higher degree of oxidation of ASOA. The ASOA components in mixed ABSOA enhanced aerosol hygroscopicity. Changing the ASOA fraction by adding biogenic VOC (BVOC) to ASOA or vice versa (AVOC to BSOA) changed the hygroscopicity of aerosol, in line with the change in the degree of oxidation of aerosol. However, the hygroscopicity of ABSOA cannot be described by a simple linear combination of pure BSOA and ASOA systems. This indicates that additional processes, possibly oligomerization, affected the hygroscopicity.

    Closure analysis of CCN and HTDMA data showed κHTDMA was lower than κCCN by 30-70 %. Better closure was achieved for ASOA compared to BSOA. This

  2. Effect of hygroscopic growth on the aerosol light-scattering coefficient: A review of measurements, techniques and error sources

    NASA Astrophysics Data System (ADS)

    Titos, G.; Cazorla, A.; Zieger, P.; Andrews, E.; Lyamani, H.; Granados-Muñoz, M. J.; Olmo, F. J.; Alados-Arboledas, L.

    2016-09-01

    Knowledge of the scattering enhancement factor, f(RH), is important for an accurate description of direct aerosol radiative forcing. This factor is defined as the ratio between the scattering coefficient at enhanced relative humidity, RH, to a reference (dry) scattering coefficient. Here, we review the different experimental designs used to measure the scattering coefficient at dry and humidified conditions as well as the procedures followed to analyze the measurements. Several empirical parameterizations for the relationship between f(RH) and RH have been proposed in the literature. These parameterizations have been reviewed and tested using experimental data representative of different hygroscopic growth behavior and a new parameterization is presented. The potential sources of error in f(RH) are discussed. A Monte Carlo method is used to investigate the overall measurement uncertainty, which is found to be around 20-40% for moderately hygroscopic aerosols. The main factors contributing to this uncertainty are the uncertainty in RH measurement, the dry reference state and the nephelometer uncertainty. A literature survey of nephelometry-based f(RH) measurements is presented as a function of aerosol type. In general, the highest f(RH) values were measured in clean marine environments, with pollution having a major influence on f(RH). Dust aerosol tended to have the lowest reported hygroscopicity of any of the aerosol types studied. Major open questions and suggestions for future research priorities are outlined.

  3. CCN activation and hygroscopic growth measurements of secondary organic aerosols from tree emissions

    NASA Astrophysics Data System (ADS)

    Buchholz, Angela; Mentel, Thomas F.; Kiendler-Scharr, Astrid; Spindler, Christian; Tillmann, Ralf; Kleist, Einhard; Wildt, Juergen

    2010-05-01

    Plant emitted volatile organic compounds (VOCs) are a major precursor of secondary organic aerosols (SOA), an important constituent of atmospheric aerosols. We used the Juelich Plant Atmosphere Chamber (JPAC) at the Research Center Juelich to investigate the microphysical properties of aerosols. SOA particles were produced from the ozonolysis and reaction of OH radicals with the complex VOC mixture emitted from trees typical for the boreal forest. Hygroscopic growth factors (GF) were determined with a humidity tandem differential mobility analyzer (HTDMA) for different particle sizes at RH = 2 - 97%. Cloud condensation nuclei (CCN) activation was measured with a continuous flow CCN counter (DMT). Additionally, the chemical composition, size distribution and number concentration of the particles were measured. The gas phase was monitored with GC-MS and PTR-MS. Changing the emission pattern of the trees changed the measured GF and the diameter of the dry particles that were activated (Dcrit). However, below 80% RH the GF changes are within the range of the measurement error. The GF (RH = 95%) are between 1.11 and 1.19 and the Dcrit(SS = 0.4%) in a range of 93 - 100nm. Koehler theory was applied to achieve closure between CCN activation and GF measurements. The κ parameter according to Petters and Kreidenweis (2007) was calculated for all SS (κ(CCN)) and RH (κ(GF)). The κ(GF) decrease with increasing RH but levels off at RH > 95%. Assuming the surface tension of pure water, κ(GF, RH>95%) would be by a factor of 2 lower than κ(CCN). Closure between the HTDMA and CCN measurement requires the use of either a lower surface tension or a limited solubility of the organic material. Reference: Petters, M. D. and Kreidenweis, S. M. (2007). Atmos. Chem. Phys., 7, 1961-1971.

  4. Hygroscopic growth of urban aerosol particles in Beijing (China) during wintertime: a comparison of three experimental methods

    NASA Astrophysics Data System (ADS)

    Meier, J.; Wehner, B.; Massling, A.; Birmili, W.; Nowak, A.; Gnauk, T.; Brüggemann, E.; Herrmann, H.; Min, H.; Wiedensohler, A.

    2009-09-01

    The hygroscopic properties of atmospheric aerosols are highly relevant for the quantification of radiative effects in the atmosphere, but also of interest for the assessment of particle health effects upon inhalation. This article reports measurements of aerosol particle hygroscopicity in the highly polluted urban atmosphere of Beijing, China in January 2005. The meteorological conditions corresponded to a relatively cold and dry atmosphere. Three different methods were used: 1) A combination of Humidifying Differential Mobility Particle Sizer (H-DMPS) and Twin Differential Mobility Particle Sizer (TDMPS) measurements, 2) A Hygroscopic Tandem Differential Mobility Analyzer (H-TDMA), and 3) A simplistic solubility model fed by chemical particle composition determined from Micro Orifice Uniform Deposit Impactor (MOUDI) samples. From the H-DMPS and TDMPS particle number size distributions, a size-resolved descriptive hygroscopic growth factor (DHGF) was determined for the relative humidities (RH) 55%, 77% and 90%, and particle diameters between 30 and 400 nm. In Beijing, the highest DHGFs were observed for accumulation mode particles, 1.40 (±0.03) at 90% RH. DHGF decreased significantly with particle size, reaching 1.04 (±0.15) at 30 nm. H-TDMA data also suggest a decrease in growth factor towards the biggest particles investigated (350 nm), associated with an increasing fraction of nearly hydrophobic particles. The agreement between the H-DMPS/TDMPS and H-TDMA methods was satisfactory in the accumulation mode size range (100-400 nm). In the Aitken mode range (<100 nm), the H-DMPS/TDMPS method yielded growth factors lower by up to 0.1 at 90% RH. The application of the solubility model based on measured chemical composition clearly reproduced the size-dependent trend in hygroscopic particle growth observed by the other methods. In the case of aerosol dominated by inorganic ions, the composition-derived growth factors tended to agree (± 0.05) or underestimate (up to

  5. Aerosol mixing-state, hygroscopic growth and cloud activation efficiency during MIRAGE 2006

    NASA Astrophysics Data System (ADS)

    Lance, S.; Raatikainen, T.; Onasch, T.; Worsnop, D. R.; Yu, X.-Y.; Alexander, M. L.; Stolzenburg, M. R.; McMurry, P. H.; Smith, J. N.; Nenes, A.

    2012-06-01

    Observations of aerosol hygroscopic growth and CCN activation spectra for submicron particles are reported for the T1 ground site outside of Mexico City during the MIRAGE 2006 campaign. κ-Köhler theory is used to evaluate the characteristic water uptake coefficient, κ*, for the CCN active aerosol population using both size-resolved HTDMA and size-resolved CCNc measurements. Organic mass fractions, forg, are evaluated from size-resolved aerosol mass spectrometer (AMS) measurements, from which κAMS is inferred and compared against κ*. Strong diurnal profiles of aerosol water uptake parameters and aerosol composition are observed. We find that new particle formation (NPF) events are correlated with an increased κ* and CCN-active fraction during the daytime, with greater impact on smaller particles. During NPF events, the number concentration of 40 nm particles acting as CCN can surpass by more than a factor of two the concentrations of 100 nm particles acting as CCN, at supersaturations of 0.51% ± 0.06%. We also find that at 06:00-08:00 in the morning throughout the campaign, fresh traffic emissions result in substantial changes to the chemical distribution of the aerosol, with on average 65% externally-mixed fraction for 40 nm particles and 30% externally-mixed fraction for 100 nm particles, whereas at midday nearly all particles of both sizes can be described as internally-mixed. Average activation spectra and growth factor distributions are analyzed for different time periods characterizing the daytime (with and without NPF events), the early morning "rush hour", and the entire campaign. We show that κ* derived from CCNc measurements decreases as a function of size during all time periods, while the CCN-active fraction increases as a function of size. Size-resolved AMS measurements do not predict the observed trend for κ* versus particle size, which can be attributed to unresolved mixing-state and the presence of refractory material not measured by the AMS

  6. Aerosol mixingstate, hygroscopic growth and cloud activation efficiency during MIRAGE 2006

    SciTech Connect

    Lance, Sara; Raatikainen, T.; Onasch, Timothy B.; Worsnop, Douglas R.; Yu, Xiao-Ying; Alexander, M. L.; Stolzenberg, Mark; McMurry, Peter; Smith, James N.; Nenes, Athanasios

    2013-05-15

    Observations of aerosol hygroscopic growth and CCN activation spectra for submicron particles are reported for the T1 ground site outside of Mexico City during the MIRAGE 2006 campaign. K¨ohler theory is used to evaluate the characteristic water uptake coefficient, k*, for the CCN active aerosol population using both size-resolved HTMDA and size-resolved CCNc measurements. Organic mass fractions, (forg), are evaluated from size-resolved aerosol mass spectrometer (AMS) measurements, from which kAMS is inferred and compared against k*. Strong diurnal profiles of aerosol water uptake parameters and aerosol composition are observed. We find that new particle formation (NPF) events are correlated with an increased k* and CCN-active fraction during the daytime, with greater impact on smaller particles. During NPF events, the number concentration of 40 nm particles acting as CCN can surpass by more than a factor of two the concentrations of 100 nm particles acting as CCN, at supersaturations of 0.51% +/- 0.06%. We also find that at 0600-0800 in the morning throughout the campaign, fresh traffic emissions result in substantial changes to the chemical distribution of the aerosol, with on average 65% externally-mixed fraction for 40 nm particles and 30% externally-mixed fraction for 100 nm particles, whereas at midday nearly all particles of both sizes can be described as “internally-mixed”. Average activation spectra and growth factor distributions are analyzed for different time periods characterizing the daytime (with and without NPF events), the early morning “rush hour”, and the entire campaign. We show that k* derived from CCNc measurements decreases as a function of size during all time periods, while the CCN-active fraction increases as a function of size. Size-resolved AMS measurements do not predict the observed trend for k* versus particle size, which can be attributed to unresolved mixing-state and the presence of refractory material not measured by the

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  8. Phase transitions and hygroscopic growth of aerosol particles containing humic acid and mixtures of humic acid and ammonium sulphate

    NASA Astrophysics Data System (ADS)

    Badger, C. L.; George, I.; Griffiths, P. T.; Braban, C. F.; Cox, R. A.; Abbatt, J. P. D.

    2006-03-01

    The phase transitions and hygroscopic growth of two humic acid aerosols (Aldrich sodium salt and Leonardite Standard (IHSS)) and their mixtures with ammonium sulphate have been investigated using a combination of two techniques, Fourier transform infra-red (FTIR) spectroscopy and tandem differential mobility analysis (TDMA). A growth factor of 1.16 at 85% relative humidity (RH) was found for the Aldrich humic acid which can be regarded as an upper limit for growth factors of humic-like substances (HULIS) found in atmospheric aerosol and is significantly smaller than that of typical atmospheric inorganics. We find that the humic acid aerosols exhibit water uptake over all relative humidities with no apparent phase changes, suggesting that these aerosols readily form supersaturated droplets. In the mixed particles, the humic acid component decreases the deliquescence relative humidity (DRH) and increases the efflorescence relative humidity (ERH) of the ammonium sulphate component, and there is some degree of water uptake prior to ammonium sulphate deliquescence. In addition, at low RH, the FTIR spectra show that the ammonium is present in a different chemical environment in the mixed aerosols than in crystalline ammonium sulphate, perhaps existing as a complex with the humic materials. The growth factors of the mixed aerosols are intermediate between those of the single-component aerosols and can be predicted assuming that the inorganic and organic fractions take up water independently.

  9. Phase transitions and hygroscopic growth of aerosol particles containing humic acid and mixtures of humic acid and ammonium sulphate

    NASA Astrophysics Data System (ADS)

    Badger, C. L.; George, I.; Griffiths, P. T.; Braban, C. F.; Cox, R. A.; Abbatt, J. P. D.

    2005-10-01

    The phase transitions and hygroscopic growth of two humic acid aerosols (Aldrich sodium salt and Leonardite Standard (IHSS)) and their mixtures with ammonium sulphate have been investigated using a combination of two techniques, Fourier transform infra-red (FTIR) spectroscopy and tandem differential mobility analysis (TDMA). A growth factor of 1.16 at 85% relative humdity (RH) was found for the Aldrich humic acid which can be regarded as an upper limit for growth factors of humic-like substances (HULIS) found in atmospheric aerosol and is significantly smaller than that of typical atmospheric inorganics. We find that the humic acid aerosols exhibit water uptake over all relative humidites with no apparent phase changes, suggesting that these aerosols readily form supersaturated droplets. In the mixed particles, the humic acid component decreases the deliquescence relative humidity (DRH) and increases the efflorescence relative humidity (ERH) of the ammonium sulphate component, and there is some degree of water uptake prior to ammonium sulphate deliquescence. In addition, at low RH, the FTIR spectra show that the ammonium is present in a different chemical environment in the mixed aerosols than in crystalline ammonium sulphate, perhaps existing as a complex with the humic materials. The growth factors of the mixed aerosols are intermediate between those of the single component aerosols and can be predicted assuming that the inorganic and organic fractions take up water independently.

  10. The impact of aerosol hygroscopic growth on the single-scattering albedo and its application on the NO2 photolysis rate coefficient

    NASA Astrophysics Data System (ADS)

    Tao, Jiangchuan; Zhao, Chunsheng

    2016-04-01

    Hygroscopic growth of aerosol particles can significantly affect their single-scattering albedo (ω), and consequently alters the aerosol effect on tropospheric photochemistry. In this study, the impact of aerosol hygroscopic growth on ω and its application to the NO2 photolysis rate coefficient (JNO2) are investigated for a typical aerosol particle population in the North China Plain (NCP). The variations of aerosol optical properties with relative humidity (RH) are calculated using a Mie theory aerosol optical model, on the basis of field measurements of number-size distribution and hygroscopic growth factor (at RH values above 90 %) from the 2009 HaChi (Haze in China) project. Results demonstrate that ambient ω has pronouncedly different diurnal patterns from ω measured at dry state, and is highly sensitive to the ambient RHs. Ambient ω in the NCP can be described by a dry state ω value of 0.863, increasing with the RH following a characteristic RH dependence curve. A Monte Carlo simulation shows that the uncertainty ofω from the propagation of uncertainties in the input parameters decreases from 0.03 (at dry state) to 0.015 (RHs > 90 %). The impact of hygroscopic growth on ω is further applied in the calculation of the radiative transfer process. Hygroscopic growth of the studied aerosol particle population generally inhibits the photolysis of NO2 at the ground level, whereas accelerates it above the moist planetary boundary layer. Compared with dry state, the calculated JNO2 at RH of 98 % at the height of 1 km increases by 30.4 %, because of the enhancement of ultraviolet radiation by the humidified scattering-dominant aerosol particles. The increase of JNO2 due to the aerosol hygroscopic growth above the upper boundary layer may affect the tropospheric photochemical processes and this needs to be taken into account in the atmospheric chemical models.

  11. Hygroscopic Characteristics of Alkylaminium Carboxylate Aerosols.

    PubMed

    Gomez-Hernandez, Mario; McKeown, Megan; Secrest, Jeremiah; Marrero-Ortiz, Wilmarie; Lavi, Avi; Rudich, Yinon; Collins, Don R; Zhang, Renyi

    2016-03-01

    The hygroscopic growth factor (HGF) and cloud condensation nuclei (CCN) activity for a series of alkylaminium carboxylate aerosols have been measured using a hygroscopicity tandem differential mobility analyzer coupled to a condensation particle counter and a CCN counter. The particles, consisting of the mixtures of mono- (acetic, propanoic, p-toluic, and cis-pinonic acid) and dicarboxylic (oxalic, succinic, malic, adipic, and azelaic acid) acid with alkylamine (mono-, di-, and trimethylamines), represent those commonly found under diverse environmental conditions. The hygroscopicity parameter (κ) of the alkylaminium carboxylate aerosols was derived from the HGF and CCN results and theoretically calculated. The HGF at 90% RH is in the range of 1.3 to 1.8 for alkylaminium monocarboxylates and 1.1 to 2.2 for alkylaminium dicarboxylates, dependent on the molecular functionality (i.e., the carboxylic or OH functional group in organic acids and methyl substitution in alkylamines). The κ value for all alkylaminium carboxylates is in the range of 0.06-1.37 derived from the HGF measurements at 90% RH, 0.05-0.49 derived from the CCN measurements, and 0.22-0.66 theoretically calculated. The measured hygroscopicity of the alkylaminium carboxylates increases with decreasing acid to base ratio. The deliquescence point is apparent for several of the alkylaminium dicarboxylates but not for the alkylaminium monocarboxylates. Our results reveal that alkylaminium carboxylate aerosols exhibit distinct hygroscopic and deliquescent characteristics that are dependent on their molecular functionality, hence regulating their impacts on human health, air quality, and direct and indirect radiative forcing on climate. PMID:26794419

  12. Characterization of solvent-extractable organics in urban aerosols based on mass spectrum analysis and hygroscopic growth measurement.

    PubMed

    Mihara, Toshiyuki; Mochida, Michihiro

    2011-11-01

    To characterize atmospheric particulate organics with respect to polarity, aerosol samples collected on filters in the urban area of Nagoya, Japan, in 2009 were extracted using water, methanol, and ethyl acetate. The extracts were atomized and analyzed using a high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) and a hygroscopicity tandem differential mobility analyzer. The atmospheric concentrations of the extracted organics were determined using phthalic acid as a reference material. Comparison of the organic carbon concentrations measured using a carbon analyzer and the HR-ToF-AMS suggests that organics extracted with water (WSOM) and ethyl acetate (EASOM) or those extracted with methanol (MSOM) comprise the greater part of total organics. The oxygen-carbon ratios (O/C) of the extracted organics varied: 0.51-0.75 (WSOM), 0.37-0.48 (MSOM), and 0.27-0.33 (EASOM). In the ion-group analysis, WSOM, MSOM, and EASOM were clearly characterized by the different fractions of the CH and CO(2) groups. On the basis of the hygroscopic growth measurements of the extracts, κ of organics at 90% relative humidity (κ(org)) were estimated. Positive correlation of κ(org) with O/C (r 0.70) was found for MSOM and EASOM, but no clear correlation was found for WSOM. PMID:21877700

  13. Hygroscopic growth of water-soluble matter extracted from remote marine aerosols over the western North Pacific: Influence of pollutants transported from East Asia.

    PubMed

    Boreddy, S K R; Kawamura, K

    2016-07-01

    We examined the hygroscopic properties of water-soluble matter (WSM) nebulized from water extracts of total suspended particles (TSP) collected at Chichijima Island in the western North Pacific during January to September 2003. The hygroscopic growth factor g(RH) of the aerosol particles was measured using a hygroscopic tandem differential mobility analyzer (HTDMA) with an initial dry particle diameter of 100nm and relative humidity (RH) of 5-95%. The measured growth factor at 90% RH, g(90%), ranged from 1.51 to 2.14 (mean: 1.76±0.15), significantly lower than that of sea salts (2.1), probably owing to the heterogeneous reactions associated with chloride depletion in sea-salt particles and water-soluble organic matter (WSOM). The g(90%) maximized in summer and minimized in spring. The decrease in spring was most likely explained by the formation of less hygroscopic salts or particles via organometallic reactions during the long-range transport of Asian dust. Cl(-) and Na(+) dominate the mass fractions of WSM, followed by nss-SO4(2-) and WSOM. Based on regression analysis, we confirmed that g(90%) at Chichijima Island largely increased due to the dominant sea spray; however, atmospheric processes associated with chloride depletion in sea salts and WSOM often suppressed g(90%). Furthermore, we explored the deviation (average: 18%) between the measured and predicted g(90%) by comparing measured and model growth factors. The present study demonstrates that long-range atmospheric transport of anthropogenic pollutants (SO2, NOx, organics, etc.) and the interactions with sea-salt particles often suppress the hygroscopic growth of marine aerosols over the western North Pacific, affecting the remote background conditions. The present study also suggests that the HCl liberation leads to the formation of less hygroscopic aerosols over the western North Pacific during long-range transport. PMID:27016676

  14. Interaction of aerosol particles composed of protein and salts with water vapor: hygroscopic growth and microstructural rearrangement

    NASA Astrophysics Data System (ADS)

    Mikhailov, E.; Vlasenko, S.; Niessner, R.; Pöschl, U.

    2003-09-01

    decomposition products NH3 and HNO3. The efflorescence threshold of NaCl-BSA particles decreased with increasing BSA dry mass fraction, i.e. the protein inhibited the formation of salt crystals and enhanced the stability of supersaturated solution droplets. The H-TDMA and TEM results indicate that the protein was enriched at the surface of the mixed particles and formed an envelope, which inhibits the access of water vapor to the particle core and leads to kinetic limitations of hygroscopic growth, phase transitions, and microstructural rearrangement processes. Besides these surface and kinetic effects, proteins and comparable organic macromolecules may also influence the thermodynamic properties of the aqueous bulk solution (solubilities, vapor pressures, and chemical equilibria, e.g. for the decomposition and evaporation of NH4NO3. The observed effects should be taken into account in the analysis of data from laboratory experiments and field measurements and in the modelling of aerosol processes involving water vapor and particles with complex composition. They can strongly influence experimental results, and depending on ambient conditions they may also play a significant role in the atmosphere (deliquescence, efflorescence, and CCN activation of particles). In fact, irregular hygroscopic growth curves similar to the ones observed in this study have recently been reported from H-TDMA experiments with water-soluble organics extracted from real air particulate matter and with humic-like substances. The Köhler theory calculations performed with different models demonstrate that the hygroscopic growth of particles composed of inorganic salts and proteins can be efficiently described with a simple volume additivity approach, provided that the correct dry solute mass equivalent diameter and composition are known. A simple parameterisation of the osmotic coefficient has been derived from an osmotic pressure virial equation and appears to be well-suited for proteins and comparable

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

    SciTech Connect

    Li, W.; Hopke, P.K.

    1993-10-01

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

  16. Discontinuous hygroscopic growth of an aqueous surfactant/salt aerosol particle levitated in an electrodynamic balance

    NASA Astrophysics Data System (ADS)

    Soonsin, V.; Krieger, U. K.; Peter, T.

    2010-12-01

    Organic compounds are a major fraction of tropospheric aerosol. The organic fraction is usually internally mixed with inorganic salts. Surface-active organic matter or surfactants, enriched in the oceanic surface layer and transferred to the atmosphere by bubble-bursting processes, are the most likely candidates to contribute the observed organic fraction in sea salt aerosol [1, 2]. If the organic substance is a surfactant, it will lower the surface tension. In addition aggregates of the organic monomers, called micelles, will form if the concentration of the organic exceeds a certain limit (critical micelle concentration). These aggregates do have different morphology (spheres or globular or rod like micelles, or spherical bilayer vesicles etc.) and size, depending on the nature of the organic molecule, its concentration and the concentration of inorganic salts [3]. These aggregate may promote solubilisation of organic compounds in aqueous atmospheric aerosol. We performed measurements of ternary aqueous solution particles consisting of tetraethylene glycol monooctyl ether (C8E4) as organic surfactant and sodium chloride (NaCl) as inorganic salt and water (H2O) using single levitated aerosol particles in an electrodynamic balance. The particles can be stored contact-free in a temperature and humidity controlled chamber and optical resonance spectroscopy is used to monitor radius change [4]. Mie resonance spectra of ternary droplets show discontinuous growth with increasing relative humidity (RH) and also discontinuous shrinkage with decreasing relative humidity. We observe this behavior at temperatures and RHs at which the salt is completely deliquesced and the concentration of the organic surfactant is larger than the critical micelle concentration. Independent measurements of particle mass show also discontinuous water uptake. We speculate that this discontinuous, step-like, growth is caused by disaggregation of a micelle needed to conserve the monolayer of

  17. Absorbing aerosols at high relative humidity: closure between hygroscopic growth and optical properties

    NASA Astrophysics Data System (ADS)

    Flores, J. M.; Bar-Or, R. Z.; Bluvshtein, N.; Abo-Riziq, A.; Kostinski, A.; Borrmann, S.; Koren, I.; Rudich, Y.

    2012-01-01

    The extinction coefficient and growth factor of humidified aerosols, at 80% and 90% RH, and at 532 nm and 355 nm wavelengths were measured for size-selected particles for ammonium sulfate, IHSS Pahokee peat (a lightly absorbing humic-like substance proxy), nigrosine (a black dye to model highly absorbing substances), and a mixture of AS and nigrosine. The ratio of the humidified extinction coefficients to the dry (fRHext(%RH, Dry)) was explored. The measured fRHext(%RH, Dry) was compared to theoretical calculations based on Mie theory, using the measured growth factors and assuming homogeneous mixing. The expected complex refractive indices (RIs) using the volume weighted mixing rule were compared to the RIs derived from the extinction measurements. Moreover, the differences between assuming a core-shell structure or a homogeneous mixing of the substances is examined. The laboratory results were used as a basis to model the change in the total extinction, the single scattering albedo (ω), and the asymmetry parameter (g) in the twilight zone of clouds at 355 nm and 532 nm. We found slightly linear to no dependency of fRH(%RH, Dry) with size for absorbing substances in contrast to the decreasing exponential behavior with size for purely scattering substances. However, no discernable difference could be made between the two wavelengths used. Less than 5% differences were found between the real parts of the complex refractive indices derived and those calculated using the volume weighted mixing rule, and the imaginary parts had up to a 20% difference. Moreover, for substances with growth factor less than 1.15 there was, in average, less than 5% difference between the extinction efficiencies calculated using a core-shell model and assuming homogeneous mixing for size parameters less than 2.5. For x>2.5 the differences were greater causing and overestimation of the extinction efficiency (Qext) values if homogenous mixing was assume instead of a core-shell structure. The

  18. Influence of semi-volatile species on particle hygroscopic growth

    NASA Astrophysics Data System (ADS)

    Villani, P.; Sellegri, K.; Monier, M.; Laj, P.

    2009-01-01

    The hygroscopic properties of aerosol particles are often related to their content of soluble material, on the basis of the Kohler theory. Recent studies, however, seem to indicate that the role of aerosol particle semi-volatile fraction properties has been underestimated. In this study, we use a novel method based on a Tandem Differential Mobility Analyser (TDMA) system combining particle volatilization and humidification conditioning (VH-TDMA) to test the effect of the gentle volatilization of a small fraction of the atmospheric particles on the particle hygroscopic growth in several environments (urban to remote). Results show that the particle hygroscopic properties can either be enhanced or decreased after thermal conditioning of the particle at moderate temperatures (50 to 110°C). The hygroscopic growth factor changes induced by volatilization indicate that some volatile compounds, although present at low concentrations, drastically influence the hygroscopic growth of particles in the way that can not be predicted by the Kohler theory at equilibrium.

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

  20. Relating hygroscopicity and composition of organic aerosol particulate matter

    SciTech Connect

    Duplissy, J.; DeCarlo, P. F.; Dommen, J.; Alfarra, M. R.; Metzger, A.; Barmpadimos, I.; Prevot, A. S. H.; Weingartner, E.; Tritscher, T.; Gysel, M.; Aiken, A. C.; Jimenez, J. L.; Canagaratna, M. R.; Worsnop, D. R.; Collins, D. R.; Tomlinson, J.; Baltensperger, U.

    2011-01-01

    A hygroscopicity tandem differential mobility analyzer (HTDMA) was used to measure the water uptake (hygroscopicity) of secondary organic aerosol (SOA) formed during the chemical and photochemical oxidation of several organic precursors in a smog chamber. Electron ionization mass spectra of the non-refractory submicron aerosol were simultaneously determined with an aerosol mass spectrometer (AMS), and correlations between the two different signals were investigated. SOA hygroscopicity was found to strongly correlate with the relative abundance of the ion signal m/z 44 expressed as a fraction of total organic signal (f44). m/z 44 is due mostly to the ion fragment CO2+ for all types of SOA systems studied, and has been previously shown to strongly correlate with organic O/C for ambient and chamber OA. The analysis was also performed on ambient OA from two field experiments at the remote site Jungfraujoch, and the megacity Mexico City, where similar results were found. A simple empirical linear relation between the hygroscopicity of OA at subsaturated RH, as given by the hygroscopic growth factor (GF) or "κorg" parameter, and f44 was determined and is given by κorg = 2.2 × f44 - 0.13. This approximation can be further verified and refined as the database for AMS and HTDMA measurements is constantly being expanded around the world. Finally, the use of this approximation could introduce an important simplification in the parameterization of hygroscopicity of OA in atmospheric models, since f44 is correlated with the photochemical age of an air mass.

  1. Aerosol optical hygroscopicity measurements during the 2010 CARES campaign

    NASA Astrophysics Data System (ADS)

    Atkinson, D. B.; Radney, J. G.; Lum, J.; Kolesar, K. R.; Cziczo, D. J.; Pekour, M. S.; Zhang, Q.; Setyan, A.; Zelenyuk, A.; Cappa, C. D.

    2015-04-01

    Measurements of the effect of water uptake on particulate light extinction or scattering made at two locations during the 2010 Carbonaceous Aerosols and Radiative Effects Study (CARES) study around Sacramento, CA are reported. The observed influence of water uptake, characterized through the dimensionless optical hygroscopicity parameter γ, is compared with calculations constrained by observed particle size distributions and size-dependent particle composition. A closure assessment has been carried out that allowed for determination of the average hygroscopic growth factors (GFs) at 85% relative humidity and the dimensionless hygroscopicity parameter κ for oxygenated organic aerosol (OA) and for supermicron particles (defined here as particles with aerodynamic diameters between 1 and 2.5 microns), yielding κ = 0.1-0.15 and 0.9-1.0, respectively. The derived range of oxygenated OA κ values are in line with previous observations. The relatively large values for supermicron particles is consistent with substantial contributions of sea-salt-containing particles in this size range. Analysis of time-dependent variations in the supermicron particle hygroscopicity suggest that atmospheric processing, specifically chloride displacement by nitrate and the accumulation of secondary organics on supermicron particles, can lead to substantial depression of the observed GF.

  2. Aerosol optical hygroscopicity measurements during the 2010 CARES campaign

    DOE PAGESBeta

    Atkinson, D. B.; Radney, J. G.; Lum, J.; Kolesar, K. R.; Cziczo, D. J.; Pekour, M. S.; Zhang, Q.; Setyan, A.; Zelenyuk, A.; Cappa, C. D.

    2015-04-17

    Measurements of the effect of water uptake on particulate light extinction or scattering made at two locations during the 2010 Carbonaceous Aerosols and Radiative Effects Study (CARES) study around Sacramento, CA are reported. The observed influence of water uptake, characterized through the dimensionless optical hygroscopicity parameter γ, is compared with calculations constrained by observed particle size distributions and size-dependent particle composition. A closure assessment has been carried out that allowed for determination of the average hygroscopic growth factors (GFs) at 85% relative humidity and the dimensionless hygroscopicity parameter κ for oxygenated organic aerosol (OA) and for supermicron particles (defined heremore » as particles with aerodynamic diameters between 1 and 2.5 microns), yielding κ = 0.1–0.15 and 0.9–1.0, respectively. The derived range of oxygenated OA κ values are in line with previous observations. The relatively large values for supermicron particles is consistent with substantial contributions of sea-salt-containing particles in this size range. Analysis of time-dependent variations in the supermicron particle hygroscopicity suggest that atmospheric processing, specifically chloride displacement by nitrate and the accumulation of secondary organics on supermicron particles, can lead to substantial depression of the observed GF.« less

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

    PubMed Central

    Longest, P. Worth; Hindle, Michael

    2011-01-01

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

  4. Aerosol optical hygroscopicity measurements during the 2010 CARES Campaign

    DOE PAGESBeta

    Atkinson, D. B.; Radney, J. G.; Lum, J.; Kolesar, K. R.; Cziczo, D. J.; Pekour, M. S.; Zhang, Q.; Setyan, A.; Zelenyuk, A.; Cappa, C. D.

    2014-12-10

    Measurements of the effect of water uptake on particulate light extinction or scattering made at two locations during the 2010 CARES study around Sacramento, CA are reported. The observed influence of water uptake, characterized through the dimensionless optical hygroscopicity parameter γ, is compared with calculations constrained by observed particle size distributions and size-dependent particle composition. A closure assessment has been carried out that allowed for determination of the average hygroscopic growth factors (GF) at 85% relative humidity and the dimensionless hygroscopicity parameter κ for oxygenated organic aerosol (OA) and for supermicron particles, yielding κ = 0.1–0.15 and 0.9–1.0, respectively. Themore » derived range of oxygenated OA κ values are in line with previous observations. The relatively large values for supermicron particles is consistent with substantial contributions of sea salt-containing particles in this size range. Analysis of time-dependent variations in the supermicron particle hygroscopicity suggest that atmospheric processing, specifically chloride displacement by nitrate and the accumulation of secondary organics on supermicron particles, can lead to substantial depression of the observed GF.« less

  5. Aerosol optical hygroscopicity measurements during the 2010 CARES Campaign

    NASA Astrophysics Data System (ADS)

    Atkinson, D. B.; Radney, J. G.; Lum, J.; Kolesar, K. R.; Cziczo, D. J.; Pekour, M. S.; Zhang, Q.; Setyan, A.; Zelenyuk, A.; Cappa, C. D.

    2014-12-01

    Measurements of the effect of water uptake on particulate light extinction or scattering made at two locations during the 2010 CARES study around Sacramento, CA are reported. The observed influence of water uptake, characterized through the dimensionless optical hygroscopicity parameter γ, is compared with calculations constrained by observed particle size distributions and size-dependent particle composition. A closure assessment has been carried out that allowed for determination of the average hygroscopic growth factors (GF) at 85% relative humidity and the dimensionless hygroscopicity parameter κ for oxygenated organic aerosol (OA) and for supermicron particles, yielding κ = 0.1-0.15 and 0.9-1.0, respectively. The derived range of oxygenated OA κ values are in line with previous observations. The relatively large values for supermicron particles is consistent with substantial contributions of sea salt-containing particles in this size range. Analysis of time-dependent variations in the supermicron particle hygroscopicity suggest that atmospheric processing, specifically chloride displacement by nitrate and the accumulation of secondary organics on supermicron particles, can lead to substantial depression of the observed GF.

  6. Estimation of aerosol optical properties considering hygroscopicity and light absorption

    NASA Astrophysics Data System (ADS)

    Jung, Chang Hoon; Lee, Ji Yi; Kim, Yong Pyo

    2015-03-01

    In this study, the influences of water solubility and light absorption on the optical properties of organic aerosols were investigated. A size-resolved model for calculating optical properties was developed by combining thermodynamic hygroscopic growth and aerosol dynamics models. The internal mixtures based on the homogeneous and core-shell mixing were compared. The results showed that the radiative forcing (RF) of Water Soluble Organic Carbon (WSOC) aerosol can be estimated to range from -0.07 to -0.49 W/m2 for core-shell mixing and from -0.09 to -0.47 W/m2 for homogeneous mixing under the simulation conditions (RH = 60%). The light absorption properties of WSOC showed the mass absorption efficiency (MAE) of WSOC can be estimated 0.43-0.5 m2/g, which accounts for 5-10% of the MAE of elemental carbon (EC). The effect on MAE of increasing the imaginary refractive index of WSOC was also calculated, and it was found that increasing the imaginary refractive index by 0.001i enhanced WSOC aerosol absorption by approximately 0.02 m2/g. Finally, the sensitivity test results revealed that changes in the fine mode fraction (FMF) and in the geometric mean diameter of the accumulation mode play important roles in estimating RF during hygroscopic growth.

  7. Influence of semi-volatile species on particle hygroscopic growth

    NASA Astrophysics Data System (ADS)

    Villani, Paolo; Sellegri, Karine; Monier, Marie; Laj, Paolo

    2013-11-01

    In this study, we use a Tandem Differential Mobility Analyser (TDMA) system combining particle volatilization and humidification conditioning (VH-TDMA) to test the effect of the gentle volatilization of a small fraction of the atmospheric particles on the particle hygroscopic growth in several environments (urban to remote). We first give an overview of the Hygroscopic Growth Factors (HGF) in these various environments, showing that in most of them, aerosol particles are externally mixed. We then show that the particle hygroscopicity can either be increased or decreased after thermal conditioning of the particle at moderate temperatures (50-110 °C). The hygroscopic growth factor changes induced by volatilization indicate that some volatile compounds, although present at low concentrations, can significantly influence the hygroscopic growth of particles in a way that can most of time be theoretically explained if simplified assumptions are used. However, simplified assumptions occasionally fail over several hours to explain hygroscopic changes, kinetic/surface effects observed at remote environments are suspected to be important.

  8. Aerosol Nucleation Frequency and Hygroscopicity at a Forested Site in the Southeastern United States

    NASA Astrophysics Data System (ADS)

    O'Halloran, T. L.; Fuentes, J. D.; Collins, D. R.; Cleveland, M. J.

    2007-12-01

    This paper examines how aerosol hygroscopicity and nucleation frequency, measured with a tandem differential mobility analyzer (TDMA) at a rural site in the southeastern United States, vary with air mass source regions and transport pathways. We also examine an observed enhancement in aerosol hygroscopicity during nucleation events. During October through December, 2006, a TDMA was used to measure submicron aerosol size distributions and size-resolved hygroscopicity at a forested site in the southeastern U.S. Measurements were conducted above a mixed deciduous forest at the Virginia Forest Research Facility, a newly operational permanent micrometeorological facility located approximately 20 km east of the foothills of the Blue Ridge Mountains. The site features a 40-m walkup scaffolding tower above a 20-m mixed deciduous forest with excellent fetch, and a climate controlled lab for housing instruments and data acquisition systems. Hygroscopic growth factor distributions were measured for eight dry diameters between 0.013 and 0.400 μm. Cluster analysis of back trajectories was applied to identify characteristic source regions and air mass pathways during the study period. Significant differences were found in the frequency of aerosol nucleation events and hygroscopicity amongst the five distinct pathways identified by the cluster analysis. Nucleation occurred most frequently when fast moving air masses originated from the northern central U.S. and lower central Canada. In these cases existing aerosol surface area was low, and the majority of trajectories passed directly over the Ohio River valley. Hygroscopicity generally increased with increasing dry diameter, except for the largest size bin, which had a slightly lower hygroscopicity than the next smallest size. Two clusters with short, stagnant trajectories contained aerosols with enhanced hygroscopicity at dry diameters less than 0.100 μm. Aerosol hygroscopicity was significantly enhanced, especially at small

  9. Hygroscopic behavior of multicomponent organic aerosols and their internal mixtures with ammonium sulfate

    NASA Astrophysics Data System (ADS)

    Jing, Bo; Tong, Shengrui; Liu, Qifan; Li, Kun; Wang, Weigang; Zhang, Yunhong; Ge, Maofa

    2016-03-01

    Water-soluble organic compounds (WSOCs) are important components of organics in the atmospheric fine particulate matter. Although WSOCs play an important role in the hygroscopicity of aerosols, knowledge on the water uptake behavior of internally mixed WSOC aerosols remains limited. Here, the hygroscopic properties of single components such as levoglucosan, oxalic acid, malonic acid, succinic acid, phthalic acid, and multicomponent WSOC aerosols mainly involving oxalic acid are investigated with the hygroscopicity tandem differential mobility analyzer (HTDMA). The coexisting hygroscopic species including levoglucosan, malonic acid, and phthalic acid have a strong influence on the hygroscopic growth and phase behavior of oxalic acid, even suppressing its crystallization completely during the drying process. The phase behaviors of oxalic acid/levoglucosan mixed particles are confirmed by infrared spectra. The discrepancies between measured growth factors and predictions from Extended Aerosol Inorganics Model (E-AIM) with the Universal Quasi-Chemical Functional Group Activity Coefficient (UNIFAC) method and Zdanovskii-Stokes-Robinson (ZSR) approach increase at medium and high relative humidity (RH) assuming oxalic acid in a crystalline solid state. For the internal mixture of oxalic acid with levoglucosan or succinic acid, there is enhanced water uptake at high RH compared to the model predictions based on reasonable oxalic acid phase assumption. Organic mixture has more complex effects on the hygroscopicity of ammonium sulfate than single species. Although hygroscopic species such as levoglucosan account for a small fraction in the multicomponent aerosols, they may still strongly influence the hygroscopic behavior of ammonium sulfate by changing the phase state of oxalic acid which plays the role of "intermediate" species. Considering the abundance of oxalic acid in the atmospheric aerosols, its mixtures with hygroscopic species may significantly promote water uptake

  10. Hygroscopic behavior of multicomponent organic aerosols and their internal mixtures with ammonium sulfate

    NASA Astrophysics Data System (ADS)

    Jing, B.; Tong, S. R.; Liu, Q. F.; Li, K.; Wang, W. G.; Zhang, Y. H.; Ge, M. F.

    2015-08-01

    Water soluble organic compounds (WSOCs) are important components of organics in the atmospheric fine particulate matter. Although WSOCs play an important role in the hygroscopicity of aerosols, water uptake behavior of internally mixed WSOC aerosols remains limited characterization. Here, the hygroscopic properties of single component such as levoglucosan, oxalic acid, malonic acid, succinic acid and phthalic acid and multicomponent WSOC aerosols mainly involving oxalic acid are investigated with the hygroscopicity tandem differential mobility analyzer (HTDMA). The coexisting hygroscopic species including levoglucosan, malonic acid and phthalic acid have strong influence on the hygroscopic growth and phase behavior of oxalic acid, even suppress its crystallization completely. The interactions between oxalic acid and levoglucosan are confirmed by infrared spectra. The discrepancies between measured growth factors and predictions from Extended Aerosol Inorganics Model (E-AIM) with UNIFAC method and Zdanovskii-Stokes-Robinson (ZSR) approach increase at medium and high relative humidity (RH) assuming oxalic acid in a solid state. For the internal mixture of oxalic acid with levoglucosan or succinic acid, there is enhanced water uptake at high RH due to positive chemical interactions between solutes. Organic mixture has more complex effect on the hygroscopicity of ammonium sulfate than single species. Although hygroscopic species such as levoglucosan accounts for a small fraction in the multicomponent aerosols, they may still strongly influence the hygroscopic behavior of ammonium sulfate by changing phase state of oxalic acid which plays the role of "intermediate" species. Considering the abundance of oxalic acid in the atmospheric aerosols, its mixtures with hygroscopic species may significantly promote water uptake under high RH conditions and thus affect the cloud condensation nuclei (CCN) activity, optical properties and chemical reactivity of atmospheric particles.

  11. Effects of Organic-Inorganic Interactions on the Hygroscopicity of Aerosol Particles

    NASA Astrophysics Data System (ADS)

    Zuend, A.; Lienhard, D.; Krieger, U. K.

    2013-12-01

    Aerosol hygroscopicity is an important property affecting size as well as phase transitions and viscosity of soluble or partially soluble particles following changes in ambient relative humidity (RH) and temperature. The effects of hygroscopic particle growth on the water contents and physical states of aerosol phases in turn may significantly affect multiphase chemistry, the direct effect of aerosols on climate, and the ability of specific particles to act as cloud condensation or ice nuclei. The hygroscopic growth of organic-inorganic mixtures in stable or metastable equilibrium with the RH of the surrounding air is governed by chemical thermodynamics and can be described, in principle, by adequate thermodynamic models. Organic-inorganic interactions involving dissolved ionic species in liquid (potentially highly viscous) phases tend to deviate substantially from ideal mixing and can lead to hygroscopicity behaviour deviating from simple linear additivity assumptions at given RH. The latter assumptions are employed in the Zdanovskii-Stokes-Robinson (ZSR) mixing rule, which is typically found to describe hygroscopic mass growth well in the RH range of completely liquid aerosol systems. We present a comparison and discussion of thermodynamic calculations based on the Aerosol Inorganic-Organic Mixtures Functional groups Activity Coefficients (AIOMFAC) model and hygroscopic growth factor data from new measurements with an electrodynamic balance (EDB) as well as data from the literature. We focus on the different hygroscopicity features below the full deliquescence RH of multicomponent organic-inorganic systems. Experiments and model calculations are performed for different multicomponent systems showing varying degrees of organic-inorganic miscibility, including liquid-liquid phase separation, hygroscopicity, and hysteresis effects between metastable and stable gas-aerosol equilibria. It is found that depending on the hygroscopicity of the organic aerosol fraction

  12. Application of Aerosol Hygroscopicity Measured at the Atmospheric Radiation Measurement Program's Southern Great Plains Site to Examine Composition and Evolution

    NASA Technical Reports Server (NTRS)

    Gasparini, Roberto; Runjun, Li; Collins, Don R.; Ferrare, Richard A.; Brackett, Vincent G.

    2006-01-01

    A Differential Mobility Analyzer/Tandem Differential Mobility Analyzer (DMA/TDMA) was used to measure submicron aerosol size distributions, hygroscopicity, and occasionally volatility during the May 2003 Aerosol Intensive Operational Period (IOP) at the Central Facility of the Atmospheric Radiation Measurement Program's Southern Great Plains (ARM SGP) site. Hygroscopic growth factor distributions for particles at eight dry diameters ranging from 0.012 micrometers to 0.600 micrometers were measured throughout the study. For a subset of particle sizes, more detailed measurements were occasionally made in which the relative humidity or temperature to which the aerosol was exposed was varied over a wide range. These measurements, in conjunction with backtrajectory clustering, were used to infer aerosol composition and to gain insight into the processes responsible for evolution. The hygroscopic growth of both the smallest and largest particles analyzed was typically less than that of particles with dry diameters of about 0.100 micrometers. It is speculated that condensation of secondary organic aerosol on nucleation mode particles is largely responsible for the minimal hygroscopic growth observed at the smallest sizes considered. Growth factor distributions of the largest particles characterized typically contained a nonhygroscopic mode believed to be composed primarily of dust. A model was developed to characterize the hygroscopic properties of particles within a size distribution mode through analysis of the fixed size hygroscopic growth measurements. The performance of this model was quantified through comparison of the measured fixed size hygroscopic growth factor distributions with those simulated through convolution of the size-resolved concentration contributed by each of the size modes and the mode-resolved hygroscopicity. This transformation from sizeresolved hygroscopicity to mode-resolved hygroscopicity facilitated examination of changes in the hygroscopic

  13. Hygroscopicity of dicarbonyl-amine secondary organic aerosol products investigated with HTDMA

    NASA Astrophysics Data System (ADS)

    Hawkins, L. N.; de Haan, D. O.

    2010-12-01

    Recent studies have shown the importance of amine-dicarbonyl chemistry as a secondary organic aerosol (SOA) formation pathway, producing imines, imidazoles, and N-containing oligomers. Preliminary work in our group has suggested that some of these products may be surface active. Therefore, the presence of these products may result in important changes to submicron particle hygroscopicity that affect aerosol scattering and cloud condensation nuclei (CCN) activity, especially in regions with significant amine-containing particles. To investigate their hygroscopicity, we have designed a hygroscopicity tandem differential mobility analyzer (HTDMA) system around a 300 L Teflon chamber that allows for longer humidification times needed for some organic aerosol components that are only slightly hygroscopic. This modification provides a range of residence times from 2.5 minutes up to 1 hour, unlike previously published systems that vary from 2-30 seconds. Using the modified hygroscopicity tandem differential mobility analyzer (HTDMA), we have measured the hygroscopic growth factor (HGF) of SOA formed from reactions of glyoxal (and methylglyoxal) with methylamine, ammonium sulfate, and several amino acids. Changes to inorganic aerosol HGF in response to the presence of SOA products are also investigated.

  14. Hygroscopic Properties of Atmospheric Aerosol Measured with an HTDMA in an Urban Background Site in Madrid

    NASA Astrophysics Data System (ADS)

    Alonso-Blanco, E.; Gómez-Moreno, F. J.; Becerril, M.; Coz, E.; Artíñano, B.

    2015-12-01

    The observation of high aerosol hygroscopic growth in Madrid is mainly limited to specific atmospheric conditions, such as local stagnation episodes, which take place in winter time. One of these episodes was identified in December 2014 and the hygroscopic growth factor (GF) measurements obtained in such episode were analysed in order to know the influence of the meteorological conditions on aerosol hygroscopic properties. The prevailing high atmospheric stability triggered an increase of the particle total concentration during the study period, with several peaks that exceeded 4.0 104 particles cm-3, as well as an increase in the inorganic fraction of the aerosol, the NO3- concentration, which in this case corresponded to 25% of the total PM1 non-refractory composition. The aerosol hygroscopic growth distribution was bimodal during the episode, with an average GF around 1.2 for the five dry particle sizes measured and an average GF spread ≥ 0.15. In addition, it is important to note that when a reduction in the concentrations of NO3- is observed, it coincides with a decrease of the GF and its spread. These data suggest, on the one hand, a high degree of external mixing state of the aerosol during the episode and, on the other hand, a notable association between the GF and the inorganic fraction of the aerosol.

  15. Hygroscopic Behavior of Multicomponent Aerosols Involving NaCl and Dicarboxylic Acids.

    PubMed

    Peng, Chao; Jing, Bo; Guo, Yu-Cong; Zhang, Yun-Hong; Ge, Mao-Fa

    2016-02-25

    Atmospheric aerosols are usually complex mixtures of inorganic and organic compounds. The hygroscopicity of mixed particles is closely related to their chemical composition and interactions between components, which is still poorly understood. In this study, the hygroscopic properties of submicron particles composed of NaCl and dicarboxylic acids including oxalic acid (OA), malonic acid (MA), and succinic acid (SA) with various mass ratios are investigated with a hygroscopicity tandem differential mobility analyzer (HTDMA) system. Both the Zdanovskii-Stokes-Robinson (ZSR) method and extended aerosol inorganics model (E-AIM) are applied to predict the water uptake behaviors of sodium chloride/dicarboxylic acid mixtures. For NaCl/OA mixed particles, the measured growth factors were significantly lower than predictions from the model methods, indicating a change in particle composition caused by chloride depletion. The hygroscopic growth of NaCl/MA particles was well described by E-AIM, and that of NaCl/SA particles was dependent upon mixing ratio. Compared with model predictions, it was determined that water uptake of the NaCl/OA mixture could be enhanced and could be closer to the predictions by addition of levoglucosan or malonic acid, which retained water even at low relative humidity (RH), leading to inhibition of HCl evaporation during dehydration. These results demonstrate that the coexisting hygroscopic species have a strong influence on the phase state of particles, thus affecting chemical interactions between inorganic and organic compounds as well as the overall hygroscopicity of mixed particles. PMID:26820230

  16. Hygroscopic properties of aerosol formed by oxidation of limonene, α-pinene, and β-pinene

    NASA Astrophysics Data System (ADS)

    Virkkula, Aki; van Dingenen, Rita; Raes, Frank; Hjorth, Jens

    1999-02-01

    The hygroscopic properties of aerosol formed by oxidation of three monoterpenes, limonene, α-pinene, and β-pinene, were measured using a tandem differential mobility analyzer (TDMA). The experiments were performed in the European Photoreactor (EUPHORE) in Valencia, Spain. The experiments included ozonolysis and photooxidation with and without ammonium sulfate seed aerosol. Pure organic particles, formed by oxidation of the terpenes in the absence of the seed aerosol, proved to be slightly hygroscopic. The hygroscopic growth factor (G) was close to 1.10 at relative humidity 84% ± 1%, which is often observed as the G of the less hygroscopic mode of atmospheric aerosol in field measurements. In the experiments with ammonium sulfate seed aerosol G decreased from approximately 1.5 before the start of terpene oxidation to approximately 1.1 as the oxidation products condensed on the particles. G was not proportional to the organic layer thickness but decreased with increasing organic volume fraction. Our analysis shows that in the internally mixed particles, ammonium sulfate and the organic products take up water independently of one another.

  17. Hygroscopic properties of ultrafine aerosol particles in the boreal forest: diurnal variation, solubility and the influence of sulfuric acid

    NASA Astrophysics Data System (ADS)

    Ehn, M.; Petäjä, T.; Aufmhoff, H.; Aalto, P.; Hämeri, K.; Arnold, F.; Laaksonen, A.; Kulmala, M.

    2006-10-01

    Freshly formed atmospheric aerosol particles are neither large enough to efficiently scatter incoming solar radiation nor able to act as cloud condensation nuclei. As the particles grow larger, their hygroscopicity determines the limiting size after which they are important in both of the aforementioned processes. The condensing species resulting in growth alter the hygroscopicity of the particles. We have measured hygroscopic growth of aerosol particles present in a boreal forest, along with the very hygroscopic atmospheric trace gas sulfuric acid. The focus was on days with new particle formation by nucleation. The measured hygroscopic growth factors (GF) correlated positively with gaseous phase sulfuric acid concentrations. This correlation had a strong size dependency; the smaller the particle, the more condensing sulfuric acid is bound to alter the GF due to initially smaller mass. In addition, water uptake of nucleation mode particles was monitored during new particle formation events and followed during their growth to Aitken mode sizes. As the modal diameter increased, the solubility of the particles decreased. This indicated that initially more hygroscopic particles transformed into less hygroscopic or even hydrophobic particles. A similar behavior was seen also during days with no particle formation, with GF decreasing during the evenings and increasing during early morning. This can be tentatively explained by day- and nighttime differences in the hygroscopicity of condensable vapors.

  18. Vertical profiling of aerosol hygroscopic properties in the planetary boundary layer during the PEGASOS campaigns

    NASA Astrophysics Data System (ADS)

    Rosati, Bernadette; Gysel, Martin; Rubach, Florian; Mentel, Thomas F.; Goger, Brigitta; Poulain, Laurent; Schlag, Patrick; Miettinen, Pasi; Pajunoja, Aki; Virtanen, Annele; Klein Baltink, Henk; Bas Henzing, J. S.; Größ, Johannes; Gobbi, Gian Paolo; Wiedensohler, Alfred; Kiendler-Scharr, Astrid; Decesari, Stefano; Facchini, Maria Cristina; Weingartner, Ernest; Baltensperger, Urs

    2016-06-01

    Vertical profiles of the aerosol particles hygroscopic properties, their mixing state as well as chemical composition were measured above northern Italy and the Netherlands. An aerosol mass spectrometer (AMS; for chemical composition) and a white-light humidified optical particle spectrometer (WHOPS; for hygroscopic growth) were deployed on a Zeppelin NT airship within the PEGASOS project. This allowed one to investigate the development of the different layers within the planetary boundary layer (PBL), providing a unique in situ data set for airborne aerosol particles properties in the first kilometre of the atmosphere. Profiles measured during the morning hours on 20 June 2012 in the Po Valley, Italy, showed an increased nitrate fraction at ˜ 100 m above ground level (a.g.l.) coupled with enhanced hygroscopic growth compared to ˜ 700 m a. g. l. This result was derived from both measurements of the aerosol composition and direct measurements of the hygroscopicity, yielding hygroscopicity parameters (κ) of 0.34 ± 0.12 and 0.19 ± 0.07 for 500 nm particles, at ˜ 100 and ˜ 700 m a. g. l., respectively. The difference is attributed to the structure of the PBL at this time of day which featured several independent sub-layers with different types of aerosols. Later in the day the vertical structures disappeared due to the mixing of the layers and similar aerosol particle properties were found at all probed altitudes (mean κ ≈ 0.18 ± 0.07). The aerosol properties observed at the lowest flight level (100 m a. g. l.) were consistent with parallel measurements at a ground site, both in the morning and afternoon. Overall, the aerosol particles were found to be externally mixed, with a prevailing hygroscopic fraction. The flights near Cabauw in the Netherlands in the fully mixed PBL did not feature altitude-dependent characteristics. Particles were also externally mixed and had an even larger hygroscopic fraction compared to the results in Italy. The mean κ from

  19. Hygroscopic Growth and Activation of Particles containing Algea-Exudate

    NASA Astrophysics Data System (ADS)

    Wex, Heike; Fuentes, Elena; Tsagkogeorgas, Georgios; Voigtländer, Jens; Clauss, Tina; Kiselev, Alexei; Green, David; Coe, Hugh; McFiggans, Gordon; Stratmann, Frank

    2010-05-01

    A large amount of the Earth is covered by oceans, which provide a constant source of marine aerosol particles, produced due to bubble bursting processes that depend on wind speed (O'Dowd and de Leeuw, 2007). In general, marine particles can be assumed to play an important role for the Earth atmosphere on a global scale, due to their abundance and due to their effect on clouds. E.g. marine stratus and stratocumulus clouds contribute about 30% to 40% to the Earth's albedo (Randall et al., 1984). The activation of aerosol particles to cloud droplets depends on the hygroscopic properties of the particles, which, in turn, depend on their chemical composition. For marine particles, is has been and still is discussed what the effects of organic substances being present in the particles might be. These substances originate from marine biota where they enrich at the ocean surface. To mimic marine aerosol particles, algae-exudates of different algae species were mixed with artificial sea-water. These samples were used in the laboratory to produce particles via a bubble bursting process (Fuentes et al., 2009). The hygroscopic growth and activation of the (size selected) particles was measured, using LACIS (Leipzig Aerosol Cloud Interaction Simulator, Stratmann et al., 2004) and the DMT-CCNc (Cloud Condensation Nucleus counter from Droplet Measurement Technologies, Roberts and Nenes, 2005). The hygroscopic growth was measured twice, 3 and 10 seconds after humidification, and no difference in the grown size was detected, i.e. no kinetic effect was observed for the examined time range. From LACIS and CCNc measurements, the hygroscopicity was deduced through determination of the amount of ions being effective in the particle / droplet solution (Rho(ion), Wex et al., 2007). A concentration dependent non-ideal behaviour was found for particles produced from an artificial sea-water sample that contained only inorganic salts, as can be expected (see e.g. Niedermeier et al., 2008

  20. 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

  1. 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

  2. Mass-based hygroscopicity parameter interaction model and measurement of atmospheric aerosol water uptake

    NASA Astrophysics Data System (ADS)

    Mikhailov, E.; Vlasenko, S.; Rose, D.; Pöschl, U.

    2013-01-01

    organic aerosol) we present first mass-based measurements of water uptake over a wide range of relative humidity (1-99.4%) obtained with a new filter-based differential hygroscopicity analyzer (FDHA) technique. For these samples the concentration dependence of κm can be described by a simple KIM model equation based on observable mass growth factors and a total of only six fit parameters summarizing the combined effects of the dilute hygroscopicity parameters, self- and cross-interaction parameters, and solubilities of all involved chemical components. One of the fit parameters represents κm0 and can be used to predict critical dry diameters for the activation of cloud condensation nuclei (CCN) as a function of water vapor supersaturation according to Köhler theory. For sodium chloride and ammonium sulfate reference particles as well as for pristine rainforest aerosols consisting mostly of secondary organic matter, we obtained good agreement between the KIM predictions and measurement data of CCN activation. The application of KIM and mass-based measurement techniques shall help to bridge gaps in the current understanding of water uptake by atmospheric aerosols: (1) the gap between hygroscopicity parameters determined by hygroscopic growth measurements under sub-saturated conditions and by CCN activation measurements at water vapor supersaturation, and (2) the gap between the results of simplified single parameter models widely used in atmospheric or climate science and the results of complex multi-parameter ion- and molecule-interaction models frequently used in physical chemistry and solution thermodynamics (e.g., AIM, E-AIM, ADDEM, UNIFAC, AIOMFAC).

  3. Characterizing the Hygroscopicity of Nascent Sea Spray Aerosol from Synthetic Blooms

    NASA Astrophysics Data System (ADS)

    Forestieri, S.; Cappa, C. D.; Sultana, C. M.; Lee, C.; Wang, X.; Helgestad, T.; Moore, K.; Prather, K. A.; Cornwell, G.; Novak, G.; Bertram, T. H.

    2015-12-01

    Marine sea spray aerosol (SSA) particles make up a significant portion of natural aerosols and are therefore important in establishing the baseline for anthropogenic aerosol climate impacts. Scattering of solar radiation by aerosols affects Earth's radiative budget and the degree of scattering is size-dependent. Thus, aerosols scatter more light at elevated relative humidities when they grow larger via water uptake. This growth depends critically on chemical composition. SSA can become enriched in organics during phytoplankton blooms, becoming less salty and therefore less hygroscopic. Subsaturated hygroscopic growth factors at 85% relative humidity (GF(85%)) of SSA particles were quantified during two mesocosm experiments in enclosed marine aerosol reference tanks (MARTs). The two experiments were conducted with filtered seawater collected at separate times from the Scripps Institute of Oceanography Pier in La Jolla, CA. Phytoplankton blooms in each tank were induced via the addition of nutrients and photosynthetically active radiation. The "indoor" MART was illuminated with fluorescent light and the other "outdoor" MART was illuminated with sunlight. The peak chlorophyll-a concentrations were 59 micrograms/L and 341 micrograms /L for the indoor and outdoor MARTs, respectively. GF(85%) values for SSA particles were quantified using a humidified cavity ringdown spectrometer and particle size distributions. Particle composition was monitored with a single particle aerosol mass spectrometer (ATOFMS) and an Aerodyne aerosol mass spectrometer (AMS). Relationships between the observed particle GFs and the particle composition markers will be discussed.

  4. Hygroscopicity of organic compounds from biomass burning and their influence on the water uptake of mixed organic ammonium sulfate aerosols

    NASA Astrophysics Data System (ADS)

    Lei, T.; Zuend, A.; Wang, W. G.; Zhang, Y. H.; Ge, M. F.

    2014-10-01

    Hygroscopic behavior of organic compounds, including levoglucosan, 4-hydroxybenzoic acid, and humic acid, as well as their effects on the hygroscopic properties of ammonium sulfate (AS) in internally mixed particles are studied by a hygroscopicity tandem differential mobility analyzer (HTDMA). The organic compounds used represent pyrolysis products of wood that are emitted from biomass burning sources. It is found that humic acid aerosol particles only slightly take up water, starting at RH (relative humidity) above ~70%. This is contrasted by the continuous water absorption of levoglucosan aerosol particles in the range 5-90% RH. However, no hygroscopic growth is observed for 4-hydroxybenzoic acid aerosol particles. Predicted water uptake using the ideal solution theory, the AIOMFAC model and the E-AIM (with UNIFAC) model are consistent with measured hygroscopic growth factors of levoglucosan. However, the use of these models without consideration of crystalline organic phases is not appropriate to describe the hygroscopicity of organics that do not exhibit continuous water uptake, such as 4-hydroxybenzoic acid and humic acid. Mixed aerosol particles consisting of ammonium sulfate and levoglucosan, 4-hydroxybenzoic acid, or humic acid with different organic mass fractions, take up a reduced amount of water above 80% RH (above AS deliquescence) relative to pure ammonium sulfate aerosol particles of the same mass. Hygroscopic growth of mixtures of ammonium sulfate and levoglucosan with different organic mass fractions agree well with the predictions of the thermodynamic models. Use of the Zdanovskii-Stokes-Robinson (ZSR) relation and AIOMFAC model lead to good agreement with measured growth factors of mixtures of ammonium sulfate with 4-hydroxybenzoic acid assuming an insoluble organic phase. Deviations of model predictions from the HTDMA measurement are mainly due to the occurrence of a microscopical solid phase restructuring at increased humidity (morphology

  5. Reconciling Organic Aerosol Volatility, Hygroscopicity, and Oxidation State During the Colorado DISCOVER-AQ Deployment

    NASA Astrophysics Data System (ADS)

    Hite, J. R.; Moore, R.; Martin, R.; Thornhill, K. L., II; Winstead, E.; Anderson, B. E.; Nenes, A.

    2014-12-01

    The organic fraction of submicron aerosol can profoundly impact radiative forcing on climate directly, through enhancement of extinction, or indirectly through modulation of cloud formation. Semi-volatile constituents of organic ambient aerosol are of particular interest as their partitioning between the vapor and aerosol phases is not well constrained by current atmospheric models and appears to play an important role in the formation of cloud condensation nuclei (CCN) as suggested by recent research. An experimental setup consisting of a DMT CCN counter and SMPS downstream of a custom-built thermodenuder assembly was deployed during the summer 2014 DISCOVER-AQ field campaign to retrieve simultaneous, size-resolved volatility and hygroscopicity - through the use of scanning mobility CCN analysis (SMCA). Housed in the NASA Langley mobile laboratory, a suite of complimentary measurements were made available onboard including submicron aerosol composition and oxidation state provided by an HR-ToF-AMS, and aerosol optical properties provided by a range of other instruments including an SP2. Air masses sampled from locations across the Central Colorado region include influences from regional aerosol nucleation/growth events, long-range transport of Canadian biomass burning aerosols, cattle feedlot emissions and influences of the Denver urban plume - amidst a backdrop of widespread oil and gas exploration. The analysis focuses on the reconciliation of the retrieved aerosol volatility distributions and corresponding hygroscopicity and oxidation state observations, including the use of AMS factor analysis.

  6. [Hygroscopic Properties of Aerosol Particles in North Suburb of Nanjing in Spring].

    PubMed

    Xu, Bin; Zhang, Ze-feng; Li, Yan-weil; Qin, Xin; Miao, Qing; Shen, Yan

    2015-06-01

    The hygroscopic properties of submicron aerosol particles have significant effects on spectral distribution, CCN activation, climate forcing, human health and so on. A Hygroscopic Tandem Differential Mobility Analyzer (HTDMA) was utilized to analyze the hygroscopic properties of aerosol particles in the northern suburb of Nanjing during 16 April to 21 May, 2014. At relative humidity (RH) of 90%, for particles with dry diameters 30-230 nm, the probability distribution of GF (GF-PDF) shows a distinct bimodal pattern, with a dominant more-hygroscopic group and a smaller less-hygroscopic group. A contrast analysis between day and night suggests that, aerosol particles during day time have a stronger hygroscopicity and a higher number fraction of more-hygroscopic group than that at night overall. Aerosol particles during night have a higher degree of externally mixed state. Backward trajectory analysis using HYSPLIT mode reveals that, the sampling site is mainly affected by three air masses. For aitken nuclei, northwest continental air masses experience a longer aging process and have a stronger hygroscopicity. For condensation nuclei, east air masses have a stronger hygroscopicity and have a higher number fraction of more-hygroscopic group. Aerosol particles in local air masses have a high number fraction of more-hygroscopic group in the whole diameter range. PMID:26387289

  7. Hygroscopic growth and droplet activation of soot particles: uncoated, succinic or sulfuric acid coated

    NASA Astrophysics Data System (ADS)

    Henning, S.; Ziese, M.; Kiselev, A.; Saathoff, H.; Möhler, O.; Mentel, T. F.; Buchholz, A.; Spindler, C.; Michaud, V.; Monier, M.; Sellegri, K.; Stratmann, F.

    2011-10-01

    The hygroscopic growth and droplet activation of uncoated soot particles and such coated with succinic acid and sulfuric acid were investigated during the IN-11 campaign at the Aerosol Interaction and Dynamics in the Atmosphere (AIDA) facility. A GFG-1000 soot generator applying nitrogen, respectively argon as carrier gas and a miniCAST soot generator were utilized to generate soot particles. Different organic carbon (OC) to black carbon (BC) ratios were adjusted for the CAST-soot by varying the fuel to air ratio. The hygroscopic growth was investigated by means of the mobile Leipzig Aerosol Cloud Interaction Simulator (LACIS-mobile) and two different Hygroscopicity Tandem Differential Mobility Analyzers (HTDMA, VHTDMA). Two Cloud Condensation Nucleus Counter (CCNC) were applied to measure the activation of the particles. For the untreated soot particles neither hygroscopic growth nor activation was observed, with exception of a partial activation of GFG-soot generated with argon as carrier gas. Coatings of succinic acid lead to a detectable hygroscopic growth of GFG-soot and enhanced the activated fraction of GFG- (carrier gas: argon) and CAST-soot, whereas no hygroscopic growth of the coated CAST-soot was found. Sulfuric acid coatings lead to an OC-content dependent hygroscopic growth of CAST-soot. Such a dependence was not observed for activation measurements. Coating with sulfuric acid decreased the amount of Polycyclic Aromatic Hydrocarbons (PAH), which were detected by AMS-measurements in the CAST-soot, and increased the amount of substances with lower molecular weight than the initial PAHs. We assume, that these reaction products increased the hygroscopicity of the coated particles in addition to the coating substance itself.

  8. Hygroscopic growth and droplet activation of soot particles: uncoated, succinic or sulfuric acid coated

    NASA Astrophysics Data System (ADS)

    Henning, S.; Ziese, M.; Kiselev, A.; Saathoff, H.; Möhler, O.; Mentel, T. F.; Buchholz, A.; Spindler, C.; Michaud, V.; Monier, M.; Sellegri, K.; Stratmann, F.

    2012-05-01

    The hygroscopic growth and droplet activation of uncoated soot particles and such coated with succinic acid and sulfuric acid were investigated during the IN-11 campaign at the Aerosol Interaction and Dynamics in the Atmosphere (AIDA) facility. A GFG-1000 soot generator applying either nitrogen or argon as carrier gas and a miniCAST soot generator were utilized to generate soot particles. Different organic carbon (OC) to black carbon (BC) ratios were adjusted for the CAST-soot by varying the fuel to air ratio. The hygroscopic growth was investigated by means of the mobile Leipzig Aerosol Cloud Interaction Simulator (LACIS-mobile) and two different Hygroscopicity Tandem Differential Mobility Analyzers (HTDMA, VHTDMA). Two Cloud Condensation Nucleus Counter (CCNC) were applied to measure the activation of the particles. For the untreated soot particles neither hygroscopic growth nor activation was observed at a supersaturation of 1%, with exception of a partial activation of GFG-soot generated with argon as carrier gas. Coatings of succinic acid lead to a detectable hygroscopic growth of GFG-soot and enhanced the activated fraction of GFG- (carrier gas: argon) and CAST-soot, whereas no hygroscopic growth of the coated CAST-soot was found. Sulfuric acid coatings led to an OC-content dependent hygroscopic growth of CAST-soot. Such a dependence was not observed for activation measurements. Coating with sulfuric acid decreased the amount of Polycyclic Aromatic Hydrocarbons (PAH), which were detected by AMS-measurements in the CAST-soot, and increased the amount of substances with lower molecular weight than the initial PAHs. We assume that these reaction products increased the hygroscopicity of the coated particles in addition to the coating substance itself.

  9. Vertical profiling of aerosol hygroscopic properties in the planetary boundary layer during the PEGASOS campaigns

    NASA Astrophysics Data System (ADS)

    Rosati, B.; Gysel, M.; Rubach, F.; Mentel, T. F.; Goger, B.; Poulain, L.; Schlag, P.; Miettinen, P.; Pajunoja, A.; Virtanen, A.; Bialek, J.; Klein Baltink, H.; Henzing, J. S.; Größ, J.; Gobbi, G. P.; Wiedensohler, A.; Kiendler-Scharr, A.; O'Dowd, C.; Decesari, S.; Facchini, M. C.; Weingartner, E.; Baltensperger, U.

    2015-03-01

    Airborne measurements of the aerosol hygroscopic and optical properties as well as chemical composition were performed in the Netherlands and northern Italy on board of a Zeppelin NT airship during the PEGASOS field campaigns in 2012. The vertical changes in aerosol properties during the development of the mixing layer were studied. Hygroscopic growth factors (GF) at 95% relative humidity were determined using the white-light humidified optical particles spectrometer (WHOPS) for dry diameters of 300 and 500 nm particles. These measurements were supplemented by an aerosol mass spectrometer (AMS) and an aethalometer providing information on the aerosol chemical composition. Several vertical profiles between 100 and 700 m a.g. were flown just after sunrise close to the San Pietro Capofiume ground station in the Po Valley, Italy. During the early morning hours the lowest layer (newly developing mixing layer) contained a high nitrate fraction (20%) which was coupled with enhanced hygroscopic growth. In the layer above (residual layer) small nitrate fractions of ~ 2% were measured as well as low GFs. After full mixing of the layers, typically around noon and with increased temperature, the nitrate fraction decreased to 2% at all altitudes and led to similar hygroscopicity values as found in the residual layer. These distinct vertical and temporal changes underline the importance of airborne campaigns to study aerosol properties during the development of the mixed layer. The aerosol was externally mixed with 22 and 67% of the 500 nm particles in the range GF < 1.1 and GF > 1.5, respectively. Contributors to the non-hygroscopic mode in the observed size range are most likely mineral dust and biological material. Mean hygroscopicity parameters (κ) were 0.34, 0.19 and 0.18 for particles in the newly forming mixing layer, residual layer and fully mixed layer, respectively. These results agree well with those from chemical analysis which found values of κ = 0.27, 0.21 and 0

  10. 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

  11. Long term measurements of the estimated hygroscopic enhancement of aerosol optical properties

    NASA Astrophysics Data System (ADS)

    Hervo, Maxime; Sellegri, Karine; Pichon, Jean Marc; Roger, Jean Claude; Laj, Paolo

    2015-04-01

    Water vapour has a major impact on aerosol optical properties, thus on the Radiative Forcing for aerosol-radiation interaction (RFari). However there is few studies measuring this impact over a large period. Optical properties of aerosols were measured at the GAW Puy de Dôme station (1465m) over a seven year period (2006-2012). The impact of hygroscopicity on aerosol optical properties was calculated over a two year period (2010-2011). The analysis of the spatial and temporal variability of the dry optical properties showed that while no long term trend was found, a clear seasonal and diurnal variation was observed on the extensive parameters (scattering, absorption). Scattering and absorption coefficients were highest during the warm season and daytime, in concordance with the seasonality and diurnal variation of the planetary boundary layer height reaching the site. Intensive parameters (single scattering albedo, asymmetry factor, refractive index) did not show such a strong diurnal variability, but still indicated different values depending on the season. Both extensive and intensive optical parameters were sensitive to the air mass origin. A strong impact of hygroscopicity on aerosol optical properties was calculated, mainly on aerosol scattering, with a dependence on the aerosol type and the season. At 90% humidity, the scattering factor enhancement (fsca) was more than 4.4 for oceanic aerosol that have mixed with a pollution plume. Consequently, the aerosol radiative forcing was estimated to be 2.8 times higher at RH= 90% and 1.75 times higher at ambient RH when hygroscopic growth of the aerosol was considered. The hygroscopicity enhancement factor of the scattering coefficient was parameterized as a function of humidity and air mass type. To our knowledge, these results are one of the first presenting the impact of water vapour on the aerosol optical properties for a long period, and the first for a site at the border between the planetary boundary layer

  12. Hygroscopicity of internally mixed multi-component aerosol particles of atmospheric relevance

    NASA Astrophysics Data System (ADS)

    Liu, Qifan; Jing, Bo; Peng, Chao; Tong, Shengrui; Wang, Weigang; Ge, Maofa

    2016-01-01

    The hygroscopic properties of two water-soluble organic compounds (WSOCs) relevant to urban haze pollution (phthalic acid and levoglucosan) and their internally mixtures with inorganic salts (ammonium sulfate and ammonium nitrate) are investigated using a hygroscopicity tandem differential mobility analyzer (H-TDMA) system. The multi-component particles uptake water gradually in the range 5-90% relative humidity (RH). The experimental results are compared with the thermodynamic model predictions. For most mixtures, Extended Aerosol Inorganic Model (E-AIM) predictions agree well with the measured growth factors. The hygroscopic growth of mixed particles can be well described by the Zdanovskii-Stokes-Robinson (ZSR) relation as long as the mixed particles are completely liquid. ZSR calculations underestimate the water uptake of mixed particles at moderate RH due to the partial dissolution of ammonium sulfate in the organic and ammonium nitrate solution in this RH region. The phase of ammonium nitrate in the initial dry particles changes dramatically with the composition of mixtures. The presence of organics in the mixed particles can inhibit the crystallization of ammonium nitrate during the drying process and results in water uptake at low RH (RH < 60%). These results demonstrate that certain representative WSOCs can substantially influence the hygroscopicity of inorganic salts and overall water uptake of particles.

  13. Hygroscopic properties of the Paris urban aerosol in relation to its chemical composition

    NASA Astrophysics Data System (ADS)

    Kamilli, K. A.; Poulain, L.; Held, A.; Nowak, A.; Birmili, W.; Wiedensohler, A.

    2014-01-01

    Aerosol hygroscopic growth factors and chemical properties were measured as part of the MEGAPOLI "Megacities Plume Case Study" at the urban site Laboratoire d'Hygiène de la Ville de Paris (LHVP) in the city center of Paris from June to August 2009, and from January to February 2010. Descriptive hygroscopic growth factors (DGF) were derived in the diameter range from 25 to 350 nm at relative humidities of 30, 55, 75, and 90% by applying the summation method on humidified and dry aerosol size distributions measured simultaneously with a humidified differential mobility particle sizer (HDMPS) and a twin differential mobility particle sizer (TDMPS). For 90% relative humidity, the DGF varied from 1.06 to 1.46 in summer, and from 1.06 to 1.66 in winter. Temporal variations in the observed mean DGF could be well explained with a simple growth model based on the aerosol chemical composition measured by aerosol mass spectrometry (AMS) and black carbon photometry (MAAP). In particular, good agreement was observed when sulfate was the predominant inorganic factor. A clear overestimation of the predicted growth factor was found when the nitrate mass concentration exceeded values of 10 μg m-3, e.g., during winter.

  14. Hygroscopic properties of the Paris urban aerosol in relation to its chemical composition

    NASA Astrophysics Data System (ADS)

    Kamilli, K. A.; Poulain, L.; Held, A.; Nowak, A.; Birmili, W.; Wiedensohler, A.

    2013-05-01

    Aerosol hygroscopic growth factors and chemical properties were measured as part of the MEGAPOLI "Megacities Plume Case Study" at the urban site LHVP in the city center of Paris from June to August 2009, and from January to February 2010. Descriptive hygroscopic growth factors (DGF) were derived in the diameter range from 25 to 350 nm at relative humidities of 30, 55, 75, and 90% by applying the summation method on humidified and dry aerosol size distributions measured simultaneously with a humidified differential mobility particle sizer (HDMPS) and a twin differential mobility particle sizer (TDMPS). For 90% relative humidity, the DGF varied from 1.06 to 1.46 in summer, and from 1.06 to 1.66 in winter. Temporal variations in the observed mean DGF could be well explained with a simple growth model based on the aerosol chemical composition measured by aerosol mass spectrometry (AMS) and black carbon photometry (MAAP). In particular, good agreement was observed when sulfate was the predominant inorganic factor. A clear overestimation of the predicted growth factor was found when the nitrate mass concentration exceeded values of 10 μg m3, e.g. during winter.

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

    NASA Astrophysics Data System (ADS)

    Brock, Charles; Wagner, Nick; Gordon, Timothy

    2016-04-01

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

  16. Vertical profiles of cloud condensation nuclei, aerosol hygroscopicity, water uptake, and scattering across the United States

    NASA Astrophysics Data System (ADS)

    Lin, J. J.; Bougiatioti, A.; Nenes, A.; Anderson, B. E.; Beyersdorf, A. J.; Brock, C. A.; Gordon, T. D.; Lack, D.; Law, D. C.; Liao, J.; Middlebrook, A. M.; Richardson, M.; Thornhill, K. L., II; Winstead, E.; Wagner, N. L.; Welti, A.; Ziemba, L. D.

    2014-12-01

    The evolutions of vertical distributions of aerosol chemical, microphysical, hygroscopic, and optical properties present fundamental challenges to the understanding of ground-level air quality and radiative transfer, and few datasets exist to date for evaluation of atmospheric models. Data collected from recent NASA and NOAA field campaigns in the California Central Valley (DISCOVER-AQ), southeast United States (SENEX, SEAC4RS) and Texas (DISCOVER-AQ) allow for a unique opportunity to constrain vertical profiles of climate-relevant aerosol properties. This work presents in-situ aircraft measurements of cloud condensation nuclei (CCN) concentration and derivations of aerosol hygroscopicity, water uptake, and light scattering. Aerosol hygroscopicity is derived from CCN and aerosol measurements. Inorganic water uptake is calculated from aerosol composition using ISORROPIA, a chemical thermodynamic model, while organic water uptake is calculated from organic hygroscopicity. Aerosol scattering closure is performed between scattering from water uptake calculations and in-situ scattering measurements.

  17. Hygroscopic, Morphological, and Chemical Properties of Agricultural Aerosols

    NASA Astrophysics Data System (ADS)

    Hiranuma, N.; Brooks, S. D.; Cheek, L.; Thornton, D. C.; Auvermann, B. W.; Littleton, R.

    2007-12-01

    Agricultural fugitive dust is a significant source of localized air pollution in the semi-arid southern Great Plains. In the Texas Panhandle, daily episodes of ground-level fugitive dust emissions from the cattle feedlots are routinely observed in conjunction with increased cattle activity in the late afternoons and early evenings. We conducted a field study to characterize size-selected agricultural aerosols with respect to hygroscopic, morphological, and chemical properties and to attempt to identify any correlations between these properties. To explore the hygroscopic nature of agricultural particles, we have collected size-resolved aerosol samples using a cascade impactor system at a cattle feedlot in the Texas Panhandle and have used the Environmental Scanning Electron Microscope (ESEM) to determine the water uptake by individual particles in those samples as a function of relative humidity. To characterize the size distribution of agricultural aerosols as a function of time, A GRIMM aerosol spectrometer and Sequential Mobility Particle Sizer and Counter (SMPS) measurements were simultaneously performed in an overall size range of 11 nm to 20 µm diameters at a cattle feedlot. Complementary determination of the elemental composition of individual particles was performed using Energy Dispersive X-ray Spectroscopy (EDS). In addition to the EDS analysis, an ammonia scrubber was used to collect ammonia and ammonium in the gas and particulate phases, respectively. The concentration of these species was quantified offline via UV spectrophotometry at 640 nanometers. The results of this study will provide important particulate emission data from a feedyard, needed to improve our understanding of the role of agricultural particulates in local and regional air quality.

  18. Variability in morphology, hygroscopicity, and optical properties of soot aerosols during atmospheric processing

    PubMed Central

    Zhang, Renyi; Khalizov, Alexei F.; Pagels, Joakim; Zhang, Dan; Xue, Huaxin; McMurry, Peter H.

    2008-01-01

    The atmospheric effects of soot aerosols include interference with radiative transfer, visibility impairment, and alteration of cloud formation and are highly sensitive to the manner by which soot is internally mixed with other aerosol constituents. We present experimental studies to show that soot particles acquire a large mass fraction of sulfuric acid during atmospheric aging, considerably altering their properties. Soot particles exposed to subsaturated sulfuric acid vapor exhibit a marked change in morphology, characterized by a decreased mobility-based diameter but an increased fractal dimension and effective density. These particles experience large hygroscopic size and mass growth at subsaturated conditions (<90% relative humidity) and act efficiently as cloud-condensation nuclei. Coating with sulfuric acid and subsequent hygroscopic growth enhance the optical properties of soot aerosols, increasing scattering by ≈10-fold and absorption by nearly 2-fold at 80% relative humidity relative to fresh particles. In addition, condensation of sulfuric acid is shown to occur at a similar rate on ambient aerosols of various types of a given mobility size, regardless of their chemical compositions and microphysical structures. Representing an important mechanism of atmospheric aging, internal mixing of soot with sulfuric acid has profound implications on visibility, human health, and direct and indirect climate forcing. PMID:18645179

  19. Multiwavelength In-situ Aerosol Absorption, Scattering, and Hygroscopic Properties During the TEXAQS 2006 Field Campaign: Aerosol Classification and Variability

    NASA Astrophysics Data System (ADS)

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

    2006-12-01

    In-situ, three wavelength-measurements of aerosol scattering and absorption of the regional aerosol near the coast of Texas, i.e. Houston and the Houston ship channel, as well as the Gulf of Mexico were carried out onboard the NOAA research vessel Ronald H. Brown during the 2006 TEXAQS/GoMACCS field campaign in July through September 2006. Aerosol scattering, hemispheric backscattering and absorption-coefficients were measured for particles with diameters dp<10μm and dp<1μm using multiwavelength integrating nephelometers and filter-based absorption photometers (PSAPs) at 60% RH (nephelometers). Light scattering was measured as a function of RH at two additional humidities, (ca. 25%, and 85% RH). Together with the 60% RH data, this enabled determination of the hygroscopic growth curve of scattering. The extensive and intensive optical properties were used to characterize the aerosol in the Houston, TX area and the Coastal Gulf of Mexico region and to provide information critical to understanding the climatic and air quality impacts of those aerosols. Analysis focuses on how these properties change during the chemical processing of sources within the project area and how they are affected by changes in atmospheric relative humidity that accompany transport, diurnal cycles and vertical mixing. The results are relevant to radiation transfer, visibility, air quality, and interpretation of remote sensing data from lidar and satellite. The results will be presented based on a regional classification of the sampled air masses to identify distinct aerosol populations and sources and to show the temporal and spatial variability of the measured parameters. Special emphasize will be given to the physico-chemical properties of aerosols measured during extensive Saharan dust periods encountered during the cruise and several air pollution episodes and industrial plumes. Scattering hygroscopic growth will be analyzed along with the chemical composition of the aerosol and its

  20. Estimation of surface-level PM concentration from satellite observation taking into account the aerosol vertical profiles and hygroscopicity.

    PubMed

    Kim, Kwanchul; Lee, Kwon H; Kim, Ji I; Noh, Youngmin; Shin, Dong H; Shin, Sung K; Lee, Dasom; Kim, Jhoon; Kim, Young J; Song, Chul H

    2016-01-01

    Surface-level PM10 distribution was estimated from the satellite aerosol optical depth (AOD) products, taking the account of vertical profiles and hygroscopicity of aerosols over Jeju, Korea during March 2008 and October 2009. In this study, MODIS AOD data from the Terra and Aqua satellites were corrected with aerosol extinction profiles and relative humidity data. PBLH (Planetary Boundary Layer Height) was determined from MPLNET lidar-derived aerosol extinction coefficient profiles. Through statistical analysis, better agreement in correlation (R = 0.82) between the hourly PM10 concentration and hourly average Sunphotometer AOD was the obtained when vertical fraction method (VFM) considering Haze Layer Height (HLH) and hygroscopic growth factor f(RH) was used. The validity of the derived relationship between satellite AOD and surface PM10 concentration clearly demonstrates that satellite AOD data can be utilized for remote sensing of spatial distribution of regional PM10 concentration. PMID:26421659

  1. The white-light humidified optical particle spectrometer (WHOPS) - a novel airborne system to characterize aerosol hygroscopicity

    NASA Astrophysics Data System (ADS)

    Rosati, B.; Wehrle, G.; Gysel, M.; Zieger, P.; Baltensperger, U.; Weingartner, E.

    2015-02-01

    Aerosol particles experience hygroscopic growth at enhanced relative humidity (RH), which leads to changes in their optical properties. We developed the white-light humidified optical particle spectrometer (WHOPS), a new instrument to investigate the particles' hygroscopic growth. Here we present a detailed technical description and characterization of the WHOPS in laboratory and field experiments. The WHOPS consists of a differential mobility analyzer, a humidifier/bypass and a white-light aerosol spectrometer (WELAS) connected in series to provide fast measurements of particle hygroscopicity at subsaturated RH and optical properties on airborne platforms. The WELAS employs a white-light source to minimize ambiguities in the optical particle sizing. In contrast to other hygroscopicity instruments, the WHOPS retrieves information of relatively large particles (i.e., diameter D > 280 nm), therefore investigating the more optically relevant size ranges. The effective index of refraction of the dry particles is retrieved from the optical diameter measured for size-selected aerosol samples with a well-defined dry mobility diameter. The data analysis approach for the optical sizing and retrieval of the index of refraction was extensively tested in laboratory experiments with polystyrene latex size standards and ammonium sulfate particles of different diameters. The hygroscopic growth factor (GF) distribution and aerosol mixing state is inferred from the optical size distribution measured for the size-selected and humidified aerosol sample. Laboratory experiments with pure ammonium sulfate particles revealed good agreement with Köhler theory (mean bias of ~3% and maximal deviation of 8% for GFs at RH = 95%). During first airborne measurements in the Netherlands, GFs (mean value of the GF distribution) at RH = 95% between 1.79 and 2.43 with a median of 2.02 were observed for particles with a dry diameter of 500 nm. This corresponds to hygroscopicity parameters (κ

  2. Hygroscopic growth and activation of uncoated and coated soot particles and their relation to ice nucleation

    NASA Astrophysics Data System (ADS)

    Ziese, M.; Henning, S.; Mildenberger, K.; Stratmann, F.; Möhler, O.; Benz, S.; Buchholz, A.; Mentel, Th.; Aida/Lacis-Mobile-Team

    2009-04-01

    Measurements of the hygroscopic growth (HTDMA, LACIS-mobile), activation behavior (DMT-CCNC) - scope of this paper - and ice nucleation (AIDA chamber) were performed to estimate the cloud-forming potential of pure and coated soot particles. Globally, soot particles contribute up to 2.5 % to the atmospheric aerosol. In the framework of the investigations described here, soot particles were generated either applying a graphite-spark-generator (GFG1000) or a flame-soot-generator (Mini-CAST). With respect to the hygroscopic growth and activation behavior, the influences of the carrier-gas (GFG-soot), the OC-content (CAST-soot) and of different coating materials were investigated. Differences in the hygroscopic growth and activation behavior of GFG generated soot particles were found for the two carrier-gases considered. If nitrogen was used, neither hygroscopic growth nor activation were observed. In contrast, when argon was used, particles featured a slight hygroscopic growth and were easier to activate. Hygroscopic growth increases with decreasing OC-content of the CAST-soot, up to growth factor 1.04 at 98.4 % relative humidity. Lower OC-contents also result in the particles being activated more easily. Coating with sulfuric acid enhances the hygroscopic growth and activation behavior of CAST-soot for different OC-contents. If the soot (GFG & CAST) was coated with dicarboxylic acids (oxalic and succinic acid), no enhancement of hygroscopic growth and activation was observed. This is most likely due to evaporation of the coating material. In comparison to the hygroscopic growth and activation behavior, the same trends were observed in the ice-nucleation behavior. That is, the more active a particle is as cloud condensation nuclei, the better it functions as ice nuclei. GFG-soot with argon as carrier-gas acts as a better ice nuclei than GFG-soot with nitrogen. For the CAST-soot the ice-nucleation activity decreases with increasing OC-content. Coating with sulfuric acid

  3. Airborne measurements of hygroscopicity and mixing state of aerosols in the planetary boundary layer during the PEGASOS campaigns

    NASA Astrophysics Data System (ADS)

    Rosati, Bernadette; Weingartner, Ernest; Gysel, Martin; Rubach, Florian; Mentel, Thomas; Baltensperger, Urs

    2014-05-01

    Aerosols interact directly with the incident solar radiation by scattering or absorbing the light. The optical properties of an aerosol particle can strongly be altered at enhanced relative humidity (RH). Depending on the particle's chemical composition, it can experience hygroscopic growth, leading to a change in size and index of refraction compared to the dry particle (Zieger et al., 2011). Besides, aerosols can exist in different mixing states which are usually divided into internal and external mixtures. If all particles of a certain size have the same chemical composition, they are described as internally mixed, whereas if particles of equal size have different chemical composition, they are defined as externally mixed. Depending on the mixture the hygroscopic behavior will change: internally mixed aerosols will grow uniformly with increasing RH, while the different substances in external mixtures will experience different growing behaviors leading to a mode-splitting or broadened size distribution. Laboratory studies are commonly performed at dry conditions but it is known that temperature and RH as well as chemical composition are changing with altitude (Morgan et al., 2010). This further leads to the conclusion that the in-situ measurements of optical properties at different heights are crucial for climate forcing calculations. Within the Pan-European Gas-Aerosols-climate interaction Study (PEGASOS) the white- light humidified optical particle spectrometer (WHOPS) was developed and installed on the Zeppelin to investigate changes of light scattering with regard to water uptake and altitude. This instrument firstly selects a dry monodisperse aerosol by its electrical mobility and then exposes it to a well-defined RH (typically 95%). Alternately, the dry and humidified particles are measured in a white-light optical particle spectrometer (WELAS). In this way it is possible to infer the effective index of refraction of the dry particles, their hygroscopic

  4. Comparative analysis of hygroscopic properties of atmospheric aerosols at ZOTTO Siberian background station during summer and winter campaigns of 2011

    NASA Astrophysics Data System (ADS)

    Ryshkevich, T. I.; Mironov, G. N.; Mironova, S. Yu.; Vlasenko, S. S.; Chi, X.; Andreae, M. O.; Mikhailov, E. F.

    2015-09-01

    The results of measurements of hygroscopic properties and chemical analysis of atmospheric aerosol samples collected from June 10 to 20 and December 15 to 25, 2011, at the ZOTTO background stations (60.8° N, 89.35° E) in Central Siberia are presented. The sorption properties of aerosols are studied with the help of a differential analyzer of absorbed water mass in the relative humidity range of 5 to 99%. It has been found that the hygroscopic growth factor of aerosol particles collected during the winter campaign is on average 45% higher than that of the aerosol collected in the summer campaign, which leads to a 40% decrease in the critical supersaturation threshold of cloud activation of particles. The measurement data are analyzed and parameterized using a new approach that takes into account the concentration effects in the particle—water vapor system at low humidities. Based on the chemical analysis, the content of water-soluble substances in the winter sample is 2.5 times higher than in the summer sample. Here, the amount of sulfates and nitrates increases 20 and 88 times, respectively. A trajectory analysis of air mass motion shows that the increased content of inorganic ions in aerosols for the winter sample is caused by long-range transport of pollutants from industrial areas of Siberia. This difference in the chemical composition is the main source of the observed difference in hygroscopic and condensation properties of the aerosol particles.

  5. 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

  6. 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

  7. Effect of aging on morphology, hygroscopicity, and optical properties of soot aerosol

    NASA Astrophysics Data System (ADS)

    Khalizov, A. F.; Xue, H.; Pagels, J.; McMurry, P. H.; Zhang, R.

    2009-12-01

    Soot from incomplete combustion represents one of the major forms of particulate matter pollution, profoundly impacting human health, air quality, and climate. The direct and indirect radiative effects of soot aerosol depend on particle composition and morphology, which may vary significantly when aerosol is subjected to atmospheric aging. We will present an overview of a comprehensive set of experimental measurements performed in our laboratory at Texas A&M to study the effect of internal mixing with atmospheric species on morphology, hygroscopicity, and optical properties of combustion soot. In our experiments, size-classified soot aerosol was exposed to 0.1 - 1000 ppb (part per billion) mixing ratios of sulfuric acid and dicarboxylic organic acids and resulting changes particle morphology and mixing state under dry and humid conditions were characterized through mass-mobility measurements by aerosol particle mass analyzer (APM) and tandem differential mobility analyzer (TDMA). Light absorption and scattering cross-sections for well-characterized fresh and coated soot aerosol were derived using a cavity ring-down spectrometer and an integrating nephelometer in order to assess the effect of atmospheric processing on the radiative properties of atmospheric soot. Internally mixed soot shows significant changes in particle morphology, increasing with the mass fraction of the coating material and relative humidity. Restructuring was the strongest for aggregates coated by sulfuric and glutaric acids whereas succinic acid coating did not result in observable morphology change. Sulfuric acid - coated particles experienced large hygroscopic growth at sub-saturated conditions and activated to cloud droplets at atmospherically relevant supersaturations. Furthermore, coating and subsequent hygroscopic growth considerably altered the optical properties of soot aerosol, increasing light scattering and absorption cross-sections. We found that irreversible restructuring of soot

  8. Comparison Between Lidar and Nephelometer Measurements of Aerosol Hygroscopicity at the Southern Great Plains Atmospheric Radiation Measurement Site

    NASA Technical Reports Server (NTRS)

    Pahlow, M.; Feingold, G.; Jefferson, A.; Andrews, E.; Ogren, J. A.; Wang, J.; Lee, Y.-N.; Ferrare, R. A.

    2004-01-01

    Aerosol hygroscopicity has a significant effect on radiative properties of aerosols. Here a lidar method, applicable to cloud-capped, well-mixed atmospheric boundary layers, is employed to determine the hygroscopic growth factor f(RH) under unperturbed, ambient atmospheric conditions. The data used for the analysis were collected under a wide range of atmospheric aerosol levels during both routine measurement periods and during the intensive operations period (IOP) in May 2003 at the Southern Great Plains (SGP) Climate Research Facility in Oklahoma, USA, as part of the Atmospheric Radiation Measurement (ARM) program. There is a good correlation (approx. 0.7) between a lidar-derived growth factor (measured over the range 85% RH to 96% RH) with a nephelometer-derived growth factor measured over the RH range 40% to 85%. For these RH ranges, the slope of the lidar-derived growth factor is much steeper than that of the nephelometer-derived growth factor, reflecting the rapid increase in particle size with increasing RH. The results are corroborated by aerosol model calculations of lidar and nephelometer equivalent f(RH) based on in situ aerosol size and composition measurements during the IOP. It is suggested that the lidar method can provide useful measurements of the dependence of aerosol optical properties on relative humidity, and under conditions closer to saturation than can currently be achieved with humidified nephelometers.

  9. 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.

  10. Physiochemical properties of carbonaceous aerosol from agricultural residue burning: Density, volatility, and hygroscopicity

    NASA Astrophysics Data System (ADS)

    Li, Chunlin; Hu, Yunjie; Chen, Jianmin; Ma, Zhen; Ye, Xingnan; Yang, Xin; Wang, Lin; Wang, Xinming; Mellouki, Abdelwahid

    2016-09-01

    Size-resolved effective density, mixing state, and hygroscopicity of smoke particles from five kinds of agricultural residues burning were characterized using an aerosol chamber system, including a volatility/hygroscopic tandem differential mobility analyzer (V/H-TDMA) combined with an aerosol particle mass analyzer (APM). To profile relationship between the thermodynamic properties and chemical compositions, smoke PM1.0 and PM2.5 were also measured for the water soluble inorganics, mineral elements, and carbonaceous materials like organic carbon (OC) and elemental carbon (EC). Smoke particle has a density of 1.1-1.4 g cm-3, and hygroscopicity parameter (κ) derived from hygroscopic growth factor (GF) of the particles ranges from 0.20 to 0.35. Size- and fuel type-dependence of density and κ are obvious. The integrated effective densities (ρ) and hygroscopicity parameters (κ) both scale with alkali species, which could be parameterized as a function of organic and inorganic mass fraction (forg &finorg) in smoke PM1.0 and PM2.5: ρ-1 =finorg · ρinorg-1 +forg · ρorg-1 and κ =finorg ·κinorg +forg ·κorg . The extrapolated values of ρinorg and ρorg are 2.13 and 1.14 g cm-3 in smoke PM1.0, while the characteristic κ values of organic and inorganic components are about 0.087 and 0.734, which are similar to the bulk density and κ calculated from predefined chemical species and also consistent with those values observed in ambient air. Volatility of smoke particle was quantified as volume fraction remaining (VFR) and mass fraction remaining (MFR). The gradient temperature of V-TDMA was set to be consistent with the splitting temperature in the OC-EC measurement (OC1 and OC2 separated at 150 and 250 °C). Combing the thermogram data and chemical composition of smoke PM1.0, the densities of organic matter (OM1 and OM2 correspond to OC1 and OC2) are estimated as 0.61-0.90 and 0.86-1.13 g cm-3, and the ratios of OM1/OC1 and OM2/OC2 are 1.07 and 1.29 on average

  11. Multiwavelength In-situ Aerosol Absorption, Scattering, and Hygroscopic Properties During the TEXAQS 2006 Field Campaign: Aerosol Classification and Variability

    NASA Astrophysics Data System (ADS)

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

    2007-12-01

    In-situ, three wavelength-measurements of optical properties of the aerosol near the coast of Texas, i.e. in the region of Houston and the Houston ship channel, as well as in the Gulf of Mexico were carried out onboard the NOAA research vessel Ronald H. Brown during the 2006 TEXAQS/GoMACCS field campaign in July through September 2006. Aerosol scattering, hemispheric backscattering and absorption-coefficients were measured for particles with diameters dp<10μm and dp<1μm using integrating nephelometers and filter-based absorption photometers (PSAPs) at 60% RH (nephelometers). Submicrometric light scattering coefficient was measured at two additional humidities, ca. 25%, and 85% RH. Together with the 60% RH data, this enabled determination of the effect of aerosol hygroscopic growth on light scattering and an empirical light scattering growth factor. The results are relevant to radiation transfer, visibility, air quality, and interpretation of remote sensing data from lidar and satellite. The extensive and intensive optical properties along with meteorological analysis are used to characterize the aerosol in the Houston, TX region and the Coastal Gulf of Mexico and to provide information critical to understanding the climatic and air quality impacts of those aerosols. Further analysis focuses on the changes that these properties undergo during chemical processing of emissions within the project area and how they are affected by changes in atmospheric relative humidity that accompany transport, diurnal cycles and vertical mixing. The results are classified by source region and flow regime of the sampled air masses to identify distinct aerosol populations. Special emphasis is given to the physico-chemical properties of aerosols measured during two periods when Saharan dust was encountered during the cruise as well as to several air pollution episodes and plumes from industrial complexes. The combination of hygroscopic growth, light scattering and absorption

  12. Hygroscopicity of aerosol particles and CCN activity of nearly hydrophobic particles in the urban atmosphere over Japan during summer

    NASA Astrophysics Data System (ADS)

    Ogawa, Shuhei; Setoguchi, Yoshitaka; Kawana, Kaori; Nakayama, Tomoki; Ikeda, Yuka; Sawada, Yuuki; Matsumi, Yutaka; Mochida, Michihiro

    2016-06-01

    We investigated the hygroscopicity of 150 nm particles and the number-size distributions and the cloud condensation nuclei (CCN) activity of nearly hydrophobic particles in aerosols over Nagoya, Japan, during summer. We analyzed the correlations between the number concentrations of particles in specific hygroscopic growth factor (g) ranges and the mass concentrations of chemical components. This analysis suggests the association of nearly hydrophobic particles with hydrocarbon-like organic aerosol, elemental carbon and semivolatile oxygenated organic aerosol (SV-OOA), that of less hygroscopic particles with SV-OOA and nitrate and that of more hygroscopic particles with low-volatile oxygenated organic aerosol (LV-OOA) and sulfate. The hygroscopicity parameter (κ) of organics was derived based on the g distributions and chemical composition of 150 nm particles. The κ of the organics correlated positively with the fraction of the total organic mass spectral signal at m/z 44 and the volume fraction of the LV-OOA to the organics, indicating that organics with highly oxygenated structures including carboxylic acid groups contribute to the water uptake. The number-size distributions of the nearly hydrophobic particles with g around 1.0 and 1.1 correlated with the mass concentrations of chemical components. The results show that the chemical composition of the particles with g around 1.0 was different between the Aitken mode and the accumulation mode size ranges. An analysis for a parameter Fmax of the curves fitted to the CCN efficiency spectra of the particles with g around 1.0 suggests that the coating by organics associated with SV-OOA elevated the CCN activity of these particles.

  13. Relating the hygroscopic properties of submicron aerosol to both gas- and particle-phase chemical composition in a boreal forest environment

    NASA Astrophysics Data System (ADS)

    Hong, J.; Kim, J.; Nieminen, T.; Duplissy, J.; Ehn, M.; Äijälä, M.; Hao, L. Q.; Nie, W.; Sarnela, N.; Prisle, N. L.; Kulmala, M.; Virtanen, A.; Petäjä, T.; Kerminen, V.-M.

    2015-10-01

    Measurements of the hygroscopicity of 15-145 nm particles in a boreal forest environment were conducted using two Hygroscopicity Tandem Differential Mobility Analyzer (HTDMA) systems during the Pan-European Gas-Aerosols-climate interaction Study (PEGASOS) campaign in spring 2013. Measurements of the chemical composition of non-size segregated particles were also performed using a high-resolution aerosol mass spectrometer (HR-AMS) in parallel with hygroscopicity measurements. On average, the hygroscopic growth factor (HGF) of particles was observed to increase from the morning until afternoon. In case of accumulation mode particles, the main reasons for this behavior were increases in the ratio of sulfate to organic matter and oxidation level (O : C ratio) of the organic matter in the particle phase. Using an O : C dependent hygroscopic growth factor of organic matter (HGForg), fitted using the inverse Zdanovskii-Stokes-Robinson (ZSR) mixing rule, clearly improved the agreement between measured HGF and that predicted based on HR-AMS composition data. Besides organic oxidation level, the influence of inorganic species was tested when using the ZSR mixing rule to estimate the hygroscopic growth factor of organics in the aerosols. While accumulation and Aitken mode particles were predicted fairly well by the bulk aerosol composition data, the hygroscopicity of nucleation mode particles showed little correlation. However, we observed them to be more sensitive to the gas phase concentration of condensable vapors: the more sulfuric acid in the gas phase, the more hygroscopic the nucleation mode particles were. No clear dependence was found between the extremely low-volatility organics concentration (ELVOC) and the HGF of particles of any size.

  14. Hygroscopic Characteristics of Organic Laden Ambient Aerosols in Yosemite National Park

    NASA Astrophysics Data System (ADS)

    Malm, W. C.; Day, D. E.; Kreidenweis, S. M.; Collett, J. L.; Carrico, C. M.; Lee, T.; Bench, G.; Carrillo, J.

    2003-12-01

    less than 1% of PM2.5 mass. The ambient aerosol was observed to deliquesce on days when the inorganic and organic aerosol were approximately equal in concentration; however, on days when the organic component was dominant, only smooth f(RH) curves were observed. Equilibrium models, exercised in combination with Mie scattering theory, were used to predict atmospheric aerosol water content and associated increases in aerosol scattering coefficient. The analyses suggest that in most cases the hygroscopic growth of inorganic salts alone could account for the observed increase in scattering as a function of relative humidity.

  15. Relating the hygroscopic properties of submicron aerosol to both gas- and particle-phase chemical composition in a boreal forest environment

    NASA Astrophysics Data System (ADS)

    Hong, J.; Kim, J.; Nieminen, T.; Duplissy, J.; Ehn, M.; Äijälä, M.; Hao, L.; Nie, W.; Sarnela, N.; Prisle, N. L.; Kulmala, M.; Virtanen, A.; Petäjä, T.; Kerminen, V.-M.

    2015-06-01

    Measurements of the hygroscopicity of 15-145 nm particles in a boreal forest environment were conducted using two Hygroscopicity Tandem Differential Mobility Analyzer (HTDMA) systems during the Pan-European Gas-AeroSOIs-climate interaction Study (PEGASOS) campaign in spring 2013. Measurements of the chemical composition of non-size segregated particles were also performed using a High-Resolution Aerosol Mass Spectrometer (HR-AMS) in parallel with hygroscopicity measurements. On average, the hygroscopic growth factor (HGF) of particles was observed to increase from the morning until afternoon. In case of accumulation mode particles, the main reasons for this behavior were increases in the ratio of sulfate to organic matter and oxidation level (O : C ratio) of the organic matter in the particle phase. Using an O : C dependent hygroscopic growth factor of organic matter (HGForg), fitted using the inverse Zdanovskii-Stokes-Robinson (ZSR) mixing rule, clearly improved the agreement between measured HGF and that predicted based on HR-AMS composition data. Besides organic oxidation level, the influence of inorganic species was tested when using the ZSR mixing rule to estimate the hygroscopic growth factor of organics in the aerosols. While accumulation and Aitken mode particles were predicted fairly well by the bulk aerosol composition data, the hygroscopicity of nucleation mode particles showed little correlation. However, we observed them to be more sensitive to the gas phase concentration of condensable vapors: the more there was sulfuric acid in the gas phase, the more hygroscopic the nucleation mode particles were. No clear dependence was found between the extremely low-volatility organics (ELVOCs) concentration and the HGF of particles of any size.

  16. Hygroscopicity of water-soluble organic compounds in atmospheric aerosols: amino acids and biomass burning derived organic species.

    PubMed

    Chan, Man Nin; Choi, Man Yee; Ng, Nga Lee; Chan, Chak K

    2005-03-15

    Amino acids and organic species derived from biomass burning can potentially affect the hygroscopicity and cloud condensation activities of aerosols. The hygroscopicity of seven amino acids (glycine, alanine, serine, glutamine, threonine, arginine, and asparagine) and three organic species most commonly detected in biomass burning aerosols (levoglucosan, mannosan, and galactosan) were measured using an electrodynamic balance. Crystallization was observed in the glycine, alanine, serine, glutamine, and threonine particles upon evaporation of water, while no phase transition was observed in the arginine and asparagine particles even at 5% relative humidity (RH). Water activity data from these aqueous amino acid particles, except arginine and asparagine, was used to revise the interaction parameters in UNIQUAC functional group activity coefficients to give predictions to within 15% of the measurements. Levoglucosan, mannosan, and galactosan particles did not crystallize nor did they deliquesce. They existed as highly concentrated liquid droplets at low RH, suggesting that biomass burning aerosols retain water at low RH. In addition, these particles follow a very similar pattern in hygroscopic growth. A generalized growth law (Gf = (1 - RH/100)-0.095) is proposed for levoglucosan, mannosan, and galactosan particles. PMID:15819209

  17. Hygroscopic behavior of water-soluble matter extracted from biomass burning aerosols collected at a rural site in Tanzania, East Africa

    NASA Astrophysics Data System (ADS)

    Boreddy, S. K. R.; Kawamura, Kimitaka; Mkoma, Stelyus; Fu, Pingqing

    2014-11-01

    In this study, we present the hygroscopic behavior of water-soluble matter (WSM) extracted from biomass burning derived particulate matter 2.5 (PM2.5) aerosols collected at a rural background site in Tanzania during June-August 2011. Hygroscopic growth factors, g(RH), of WSM were measured by hygroscopic tandem differential mobility analyzer (H-TDMA) with an initial dry particle diameter of 100 nm. We observed that the g(RH) of WSM at 90% relative humidity (RH), g(90%)WSM, ranged from 1.10 to 1.47 with an average of 1.25 ± 0.12. The H-TDMA retrieved hygroscopicity parameter of WSM, κWSM, ranged from 0.04 to 0.24 with a mean of 0.11 ± 0.07. We found that the observed g(90%)WSM is positively correlated with PM2.5 mass fractions of K+ (R2 = 0.61), Cl- (0.54), and organic carbon (0.58). Moreover, it well correlates with levoglucosan (0.67) and total diacids (0.76), implying that although the inorganic fraction may be the most important factor to control the hygroscopicity; biomass burning organics play a significant role in the hygroscopicity of Tanzanian aerosols. The lower growth factors obtained over the sampling site are probably due to the formation of less water-soluble potassium oxalate (K2C2O4) or less hygroscopic K2SO4 particles during atmospheric aging. We observed a moderate correlation (R2 = 0.33) between PM2.5 mass fraction of WSOC and g(90%)WSM. The retrieved g(90%)WSOM values ranged from 1.0 to 1.25 with a mean of 1.16 ± 0.05. This study demonstrates that the hygroscopicity of Tanzanian aerosols is largely controlled by the emission of biomass burning products and the subsequent chemical aging during atmospheric transport.

  18. The Effect of Aerosol Hygroscopicity and Volatility on Aerosol Optical Properties During Southern Oxidant and Aerosol Study

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    Secondary organic aerosol (SOA) from biogenic sources can influence optical properties of ambient aerosol by altering its hygroscopicity and contributing to light absorption directly via formation of brown carbon and indirectly by enhancing light absorption by black carbon ("lensing effect"). The magnitude of these effects remains highly uncertain. A set of state-of-the-art instruments was deployed at the SEARCH site near Centerville, AL during the Southern Oxidant and Aerosol Study (SOAS) campaign in summer 2013 to measure the effect of relative humidity and temperature on aerosol size distribution, composition and optical properties. Light scattering and absorption by temperature- and humidity-conditioned aerosols was measured using three photo-acoustic extinctiometers (PAX) at three wavelengths (405 nm, 532 nm, and 870 nm). The sample-conditioning system provided measurements at ambient RH, 10%RH ("dry"), 85%RH ("wet"), and 200 C ("TD"). In parallel to these measurements, a long residence time temperature-stepping thermodenuder (TD) and a variable residence time constant temperature TD in combination with three SMPS systems and an Aerosol Chemical Speciation Monitor (ACSM) were used to assess aerosol volatility and kinetics of aerosol evaporation. We will present results of the on-going analysis of the collected data set. We will show that both temperature and relative humidity have a strong effect on aerosol optical properties. SOA appears to increase aerosol light absorption by about 10%. TD measurements suggest that aerosol equilibrated fairly quickly, within 2 s. Evaporation varied substantially with ambient aerosol loading and composition and meteorology.

  19. Hygroscopic properties of atmospheric aerosol particles over the Eastern Mediterranean: implications for regional direct radiative forcing under clean and polluted conditions

    NASA Astrophysics Data System (ADS)

    Stock, M.; Cheng, Y. F.; Birmili, W.; Massling, A.; Wehner, B.; Müller, T.; Leinert, S.; Kalivitis, N.; Mihalopoulos, N.; Wiedensohler, A.

    2011-05-01

    This work examines the effect of direct radiative forcing of aerosols in the eastern Mediterranean troposphere as a function of air mass composition, particle size distribution and hygroscopicity, and relative humidity (RH). During intensive field measurements on the island of Crete, Greece, the hygroscopic properties of atmospheric particles were determined using a Hygroscopicity Tandem Differential Mobility Analyzer (H-TDMA) and a Hygroscopicity Differential Mobility Analyzer-Aerodynamic Particle Sizer (H-DMA-APS). Similar to former studies, the H-TDMA identified three hygroscopic sub-fractions of particles in the sub-μm range: a more hygroscopic group, a less hygroscopic group and a nearly hydrophobic particle group. The average hygroscopic particle growth factors at 90 % RH were a significant function of particle mobility diameter (Dp): 1.42 (± 0.05) at 30 nm compared to 1.63 (± 0.07) at 250 nm. The H-DMA-APS identified up to three hygroscopic sub-fractions at mobility diameters of 1.0 and 1.2 μm. The data recorded between 12 August and 20 October 2005 were classified into four distinct synoptic-scale air mass types distinguishing between different regions of origin (western Mediterranean vs. the Aegean Sea) as well as the degree of continental pollution (marine vs. continentally influenced). The hygroscopic properties of particles with diameter Dp≥150 nm showed the most pronounced dependency on air mass origin, with growth factors in marine air masses exceeding those in continentally influenced air masses. Particle size distributions and hygroscopic growth factors were used to calculate aerosol light scattering coefficients at ambient RH using a Mie model. A main result was the pronounced enhancement of particle scattering over the eastern Mediterranean due to hygroscopic growth, both in the marine and continentally influenced air masses. When RH reached its summer daytime values around 70-80 %, up to 50-70 % of the calculated visibility reduction was

  20. Hygroscopic properties of atmospheric aerosol particles over the Eastern Mediterranean: implications for regional direct radiative forcing under clean and polluted conditions

    NASA Astrophysics Data System (ADS)

    Stock, M.; Cheng, Y. F.; Birmili, W.; Massling, A.; Wehner, B.; Müller, T.; Leinert, S.; Kalivitis, N.; Mihalopoulos, N.; Wiedensohler, A.

    2010-11-01

    This work examines the effect of direct radiative forcing of aerosols in the eastern Mediterranean troposphere as a function of air mass composition, particle size distribution and hygroscopicity, and relative humidity (RH). During intensive field measurements on the island of Crete, Greece, the hygroscopic properties of atmospheric particles were determined using a Hygroscopicity Tandem Differential Mobility Analyzer (H-TDMA) and a Hygroscopicity Differential Mobility Analyzer - Aerodynamic Particle Sizer (H-DMA-APS). Like in several studies before, the H-TDMA identified three hygroscopic sub-fractions of particles in the sub-μm range: a more hygroscopic group, a less hygroscopic group and a nearly hydrophobic particle group. The hygroscopic particle growth factors at 90% RH were a significant function of particle mobility diameter (Dp): 1.42 (± 0.05) at 30 nm compared to 1.63 (± 0.07) at 250 nm. The H-DMA-APS identified up to three hygroscopic sub-fractions at mobility diameters of 1.0 and 1.2 μm. All data recorded between 12 August and 20 October, 2005 were classified into four distinct synoptic-scale air mass types distinguishing between different regions of origin (western Mediterranean vs. the Aegean Sea) as well as the degree of continental pollution (marine vs. continentally influenced). The hygroscopic properties of particles with diameter Dp ≥ 150 nm showed the most pronounced dependency on air mass origin, with growth factors in marine air masses exceeding those in more continentally influenced air masses. Particle size distributions and hygroscopic growth factors were employed to calculate aerosol light scattering coefficients at ambient RH using a Mie model. A main result was the pronounced enhancement of particle scattering over the eastern Mediterranean due to hygroscopic growth, both in the marine and continentally influenced air masses. When RH reached its daytime values around 70-80% in summer, up to 50-70% of the calculated visibility

  1. Relationship between volatility, hygroscopicity, and CCN activity of winter aerosols: Kanpur, Indo-Gangetic Basin

    NASA Astrophysics Data System (ADS)

    Bhattu, Deepika; Tripathi, Sachchida

    2016-04-01

    Aerosol volatility is one of the key property in deciding their lifetime and fate. The volatile species have the potential to affect SOA estimation, so their characterization and establishment of relationship with mass loading, chemical composition, hygroscopicity and CCN activity is required. A 42 days long winter campaign was conducted in an anthropogenically polluted location (Kanpur, India) where CCN activity of both ambient and thermally treated aerosols was characterized. Enhanced partitioning of semi-volatile molecules into particle phase at higher loading conditions was observed. Unexpectedly, the most oxidized organic factor was observed both least volatile and hygroscopic in nature. Lower

  2. Hygroscopicity and CCN activity of atmospheric aerosol particles and their relation to organics: Characteristics of urban aerosols in Nagoya, Japan

    NASA Astrophysics Data System (ADS)

    Kawana, Kaori; Nakayama, Tomoki; Mochida, Michihiro

    2016-04-01

    The size-resolved distributions of hygroscopic growth factor g and the ratios of cloud condensation nuclei (CCN) to condensation nuclei of atmospheric aerosols were investigated in Nagoya, Japan. The average of the distributions of g at 85% relative humidity was bimodal. The size-resolved mean κ derived from g showed an increasing trend with diameter: 0.17-0.33 at 24-359 nm. The κ values calculated from CCN activation curves were 37% higher than those derived from g. Only 9% of the 37% difference is explained by the difference in the κ of inorganics under subsaturated and supersaturated conditions, suggesting a contribution of organics to the remaining 28% difference. The size-averaged κ of organics (κorg) was calculated as 0.14 and 0.19 by two different methods. The number fractions of CCN predicted from the hygroscopicity data over the range of 24-359 nm are loosely consistent with those observed if the size- and time-averaged g is applied to all particles (differences: -30% to +10%). This consistency improves if size- and time-resolved g and g distribution are used (differences: -19% to -3%). Whereas the number fractions of CCN predicted from the composition data are greatly underestimated if organics are assumed to be insoluble (differences: -64% to -45%), they are more consistent if κorg of 0.14 or 0.19 is applied (differences: -10% to +14%). The results demonstrate the importance of the dependence of the g of particles on time and particle size and the hygroscopicity of organics for CCN number concentrations in the urban atmosphere.

  3. Comparison of aerosol hygroscopicity and mixing state between winter and summer seasons in Pearl River Delta region, China

    NASA Astrophysics Data System (ADS)

    Jiang, Rongxin; Tan, Haobo; Tang, Lili; Cai, Mingfu; Yin, Yan; Li, Fei; Liu, Li; Xu, Hanbing; Chan, P. W.; Deng, Xuejiao; Wu, Dui

    2016-03-01

    Hygroscopic properties of aerosol particles are important for determining aerosol size distributions, and thus determining scattering and absorption coefficients at ambient atmospheric conditions. In this study, hygroscopic properties of aerosol particles at an urban site in Guangzhou, China, were measured using a Hygroscopic Tandem Differential Mobility Analyzer (H-TDMA) system during the winter and the summer. The results show that the urban aerosols were composed of more-hygroscopic, less-hygroscopic and non-hygroscopic particles. For less-hygroscopic particles of 40-200 nm in diameter, the hygroscopic parameter κLH was around 0.15. For more-hygroscopic particles, the κMH was from 0.290 to 0.339 with a particle size from 40 to 200 nm. For non-hygroscopic particles, the κNH was about 0.015. It was found that the number fraction of less-hygroscopic particles (NFLH) was correlated with the atmospheric oxidation which can be presented by OC/EC. This paper attributed the larger NFLH in winter to the higher value of OC/EC (3.0). Such conditions may lead to more formation of less-hygroscopic particles. Backward trajectories cluster analysis shows that there is a certain link between air mass origin and aerosol hygroscopicity, but it seems to be independent of the level of pollution. The difference of NFNH indicates that the mixing state of aerosol particles can also be affected by air mass origin. Diurnal variations in aerosol hygroscopic parameters in both seasons show that during daytime, aerosol particles tend to have a low degree of external mixing or quasi-internal mixing, resulting in a higher NFMH and a larger κmean; during nighttime and early mornings, they tend to be mixed externally, resulting in a lower NFMH and a smaller κmean. This can be attributed to atmospheric aging effect and evolution of mixing layer height and implies that soot (non-hygroscopic) particles present to a large extent as internal mixtures by the time they leave the urban

  4. Hygroscopicity of Amine Secondary Aerosol - Mixtures of Organic and Inorganic Components

    NASA Astrophysics Data System (ADS)

    Tang, X.; Cocker, D. R.; Purvis-Roberts, K.; Asa-Awuku, A. A.

    2012-12-01

    Aliphatic amines are emitted from both biogenic and anthropogenic sources and contribute to the formation of secondary aerosol in reactions with atmospheric radicals. However, the cloud condensation nuclei (CCN) ability of amine aerosol has not been explored yet. Here, we study the hygroscopicity of aerosol formed from three aliphatic amines (trimethylamine, diethylamine and butylamine) in the UCR environmental chamber. Amines can react with NO3, a dominant night time oxidant in acid-base and/or oxidation reactions. The mass fraction of organic and inorganic components of formed aerosol was measured by Particle-into-Liquid Sampler coupled to dual ion chromatographs (PILS-ICs) and Scanning Mobility Particle Sizer (SMPS). CCN counter was used to measure the water-uptake ability of these particles. Significantly high hygroscopicity (κ>0.3) was observed for aerosols formed from diethylamine and butylamine with NO3 radicals, which comprised >40% inorganic salt. Compared with amines oxidized by hydroxyl radicals, the presence of aminium salts formed in acid-base reactions greatly improved CCN activity of NO3-initiated aerosol. The effect of water vapor on the formation of aminium salts and aerosol hygroscopicity was also studied. Our results will significantly impact the estimation and role of amines in atmospheric chemistry and global climate models.

  5. Hygroscopic Properties of Aircraft Engine Exhaust Aerosol Produced From Traditional and Alternative Fuels

    NASA Astrophysics Data System (ADS)

    Moore, R.; Ziemba, L. D.; Beyersdorf, A. J.; Thornhill, K. L.; Winstead, E. L.; Crumeyrolle, S.; Chen, G.; Anderson, B. E.

    2012-12-01

    Aircraft emissions of greenhouse gases and aerosols constitute an important component of anthropogenic climate forcing, of which aerosol-cloud interactions remain poorly understood. It is currently thought that the ability of these aerosols to alter upper tropospheric cirrus cloud properties may produce radiative forcings many times larger than the impact of linear contrails alone and which may partially offset the impact of greenhouse gas emissions from aviation (Burkhardt and Karcher, Nature, 2011). Consequently, it is important to characterize the ability of these engine-emitted aerosol to act as cloud condensation nuclei (CCN) and ice nuclei (IN) to form clouds. While a number of studies in the literature have examined aerosol-cloud interactions for laboratory-generated soot or from aircraft engines burning traditional fuels, limited attention has been given to how switching to alternative jet fuels impacts the ability of engine-emitted aerosols to form clouds. The key to understanding these changes is the aerosol hygroscopicity. To address this need, the second NASA Alternative Aviation Fuel Experiment (AAFEX-II) was conducted in 2011 to examine the aerosol emissions from the NASA DC-8 under a variety of different engine power and fuel type conditions. Five fuel types were considered including traditional JP-8 fuel, synthetic Fischer-Tropsh (FT) fuel , sulfur-doped FT fuel (FTS) , hydrotreated renewable jet (HRJ) fuel, and a 50:50 blend of JP-8 with HRJ. Emissions were sampled from the DC-8 on the airport jetway at a distance of 145 meters downwind of the engine by a comprehensive suite of aerosol instrumentation that provided information on the aerosol concentration, size distribution, soot mass, and CCN activity. Concurrent measurements of carbon dioxide were used to account for plume dilution so that characteristic emissions indices could be determined. It is found that both engine power and fuel type significantly influence the hygroscopic properties of

  6. Chemical and hygroscopic properties of aerosol organics at Storm Peak Laboratory

    NASA Astrophysics Data System (ADS)

    Hallar, A. Gannet; Lowenthal, Douglas H.; Clegg, Simon L.; Samburova, Vera; Taylor, Nathan; Mazzoleni, Lynn R.; Zielinska, Barbara K.; Kristensen, Thomas B.; Chirokova, Galina; McCubbin, Ian B.; Dodson, Craig; Collins, Don

    2013-05-01

    A combined field and laboratory study was conducted to improve our understanding of the chemical and hygroscopic properties of organic compounds in aerosols sampled in the background continental atmosphere. PM2.5 (particles with aerodynamic diameters smaller than 2.5 µm) aerosols were collected from 24 June to 28 July 2010 at Storm Peak Laboratory (SPL) in the Park Range of northwestern Colorado. New particle formation (NPF) was frequent at SPL during this campaign, and the samples were not influenced by regional dust storms. Filter samples were analyzed for organic carbon (OC) and elemental carbon (EC), water soluble OC (WSOC), major inorganic ions, and detailed organic speciation. WSOC was isolated from inorganic ions using solid phase absorbents. Hygroscopic growth factors (GFs) and cloud condensation nucleus (CCN) activity of the WSOC were measured in the laboratory. Organic compounds compose the majority (average of 64% with a standard deviation (SD) of 9%) of the mass of measured species and WSOC accounted for an average of 89% (with a SD of 21%) of OC mass. Daily samples were composited according to back trajectories. On average, organic acids, sugars, and sugar alcohols accounted for 12.5 ± 6.2% (average ± SD) of WSOC. Based on the composition of these compounds and that of high molecular weight compounds identified using ultra high resolution mass spectrometry, the organic mass to OC ratio of the WSOC is estimated to be 2.04. The average hygroscopic GFs at RH = 80% (GF80) were 1.10 ± 0.03 for particles derived from isolated WSOC and 1.27 ± 0.03 for particles derived from the total water-soluble material (WSM). CCN activity followed a similar pattern. The critical diameters at a super-saturation of 0.35% were 0.072 ± 0.009 and 0.094 ± 0.006 µm for particles derived from WSM and isolated WSOC, respectively. These GF results compare favorably with estimates from thermodynamic models, which explicitly relate the water activity (RH) to concentration for

  7. 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

  8. Hygroscopic mixing state of urban aerosol derived from size-resolved cloud condensation nuclei measurements during the MEGAPOLI campaign in Paris

    NASA Astrophysics Data System (ADS)

    Jurányi, Z.; Tritscher, T.; Gysel, M.; Laborde, M.; Gomes, L.; Roberts, G.; Baltensperger, U.; Weingartner, E.

    2013-07-01

    Ambient aerosols are a complex mixture of particles with different physical and chemical properties and consequently distinct hygroscopic behaviour. The hygroscopicity of a particle determines its water uptake at subsaturated relative humidity (RH) and its ability to form a cloud droplet at supersaturated RH. These processes influence Earth's climate and the atmospheric lifetime of the particles. Cloud condensation nuclei (CCN) number size distributions (i.e. CCN number concentrations as a function of dry particle diameter) were measured close to Paris during the MEGAPOLI campaign in January-February 2010, covering 10 different supersaturations (SS = 0.1-1.0%). The time-resolved hygroscopic mixing state with respect to CCN activation was also derived from these measurements. Simultaneously, a hygroscopicity tandem differential mobility analyser (HTDMA) was used to measure the hygroscopic growth factor (ratio of wet to dry mobility diameter) distributions at RH = 90%. The aerosol was highly externally mixed and its mixing state showed significant temporal variability. The average particle hygroscopicity was relatively low at subsaturation (RH = 90%; mean hygroscopicity parameter κ = 0.12-0.27) and increased with increasing dry diameter in the range 35-265 nm. The mean κ value, derived from the CCN measurements at supersaturation, ranged from 0.08 to 0.24 at SS = 1.0-0.1%. Two types of mixing-state resolved hygroscopicity closure studies were performed, comparing the water uptake ability measured below and above saturation. In the first type the CCN counter was connected in series with the HTDMA and and closure was achieved over the whole range of probed dry diameters, growth factors and supersaturations using the κ-parametrization for the water activity and assuming surface tension of pure water in the Köhler theory. In the second closure type we compared hygroscopicity distributions derived from parallel monodisperse CCN measurements and HTDMA measurements

  9. A new experimental approach to study the hygroscopic and optical properties of aerosols: application to ammonium sulfate particles

    NASA Astrophysics Data System (ADS)

    Denjean, C.; Formenti, P.; Picquet-Varrault, B.; Katrib, Y.; Pangui, E.; Zapf, P.; Doussin, J. F.

    2014-01-01

    A new methodology for the determination of the changes due to hygroscopic growth with relative humidity of the number size distribution and optical properties of polydispersed aerosols is described. This method uses the simulation chamber CESAM where the hygroscopic properties of polydispersed aerosol particles can be investigated in situ by exposing them to RH ranging from 0 to 100% for approximately 1 h. In situ humidification is used to provide simultaneous information on the RH-dependence of the particle size and the corresponding scattering coefficient (σscat), and that for the entire size distribution. Optical closure studies, based on integrated nephelometer and aethalometer measurements, Mie scattering calculations and measured particle size distributions, can therefore be performed to yield derived parameters such as the complex refractive index (CRI) at λ = 525 nm. The CRI can also be retrieved in the visible spectrum by combining differential mobility analyzer (DMA) and white light aerosol spectrometer (Palas Welas®) measurements. We have applied this methodology to ammonium sulfate particles, which have well known optical and hygroscopic properties. The CRI obtained from the two methods (1.54-1.57) compared favourably to each other and are also in reasonable agreement with the literature values. The particle's growth was compared to values obtained for one selected size of particles (150 nm) with a H-TDMA and the effect of the residence time for particles humidification was investigated. When the humidification was performed in the chamber for a few minutes, a continuous increase of the ammonium sulfate particle's size and σscat was observed from RH values as low as 30% RH. Comparison of the measured and modelled values based on Köhler and Mie theories shows that layers of water are adsorbed on ammonium sulfate particles below the deliquescence point. In contradiction, the particle's growth reported with H-TDMAs showed a prompt deliquescence of

  10. On aerosol hygroscopicity, cloud condensation nuclei (CCN) spectra and critical supersaturation measured at two remote islands of Korea between 2006 and 2009

    NASA Astrophysics Data System (ADS)

    Kim, J. H.; Yum, S. S.; Shim, S.; Yoon, S.-C.; Hudson, J. G.; Park, J.; Lee, S.-J.

    2011-07-01

    Aerosol size distribution, total concentration (i.e., condensation nuclei (CN) concentration, NCN), cloud condensation nuclei (CCN) concentration (NCCN), hygroscopicity at ~90 % relative humidity (RH) were measured at a background monitoring site at Gosan, Jeju Island, south of the Korea Peninsula in August 2006, April to May 2007 and August to October 2008. Similar measurement took place in August 2009 at another background site (Baengnyeongdo Comprehensive Monitoring Observatory, BCMO) on the island of Baengnyeongdo, off the west coast of the Korean Peninsula. Both islands were found to be influenced by continental sources regardless of season and year. Average values for all of the measured NCCN at 0.2, 0.6 and 1.0 % supersaturations (S), NCN, and geometric mean diameter (Dg) from both islands were in the range of 1043-3051 cm-3, 2076-4360 cm-3, 2713-4694 cm-3, 3890-5117 cm-3 and 81-98 nm, respectively. Although the differences in Dg and NCN were small between Gosan and BCMO, NCCN at various S was much higher at the latter, which is closer to China. Most of the aerosols were internally mixed and no notable differences in hygroscopicity were found between the days of strong pollution influence and the non-pollution days for both islands. During the 2008 and 2009 campaigns, critical supersaturation for cloud nucleation (Sc) for selected particle sizes was measured. Particles of 100 nm diameters had mean Sc of 0.19 ± 0.02 % during 2008 and those of 81 and 110 nm diameters had mean Sc of 0.26 ± 0.07 % and 0.17 ± 0.04 %, respectively, during 2009. Hygroscopicity parameters estimated from the measured Sc were mostly higher than the ones from the measured hygroscopic growth at ~90 % RH. For the 2008 campaign, NCCN at 0.2, 0.6 and 1.0 % S were predicted based on the measured dry particle size distribution and various ways of representing aerosol hygroscopicity. The best closure was obtained when temporally varying and size-resolved hygroscopicity information from

  11. Long-term (2001-2012) observation of the modeled hygroscopic growth factor of remote marine TSP aerosols over the western North Pacific: impact of long-range transport of pollutants and their mixing states.

    PubMed

    Boreddy, S K R; Kawamura, Kimitaka; Haque, Md Mozammel

    2015-11-21

    In order to assess the seasonal and annual variability of long-range transported anthropogenic pollutants from East Asia and their effect on the hygroscopicity and precipitation process over the western North Pacific, we conducted long-term calculations of bulk hygroscopicity, g(90%)ZSR, based on the ZSR model using chemical composition data from 2001-2012 at Chichijima Island. We found that sea-salts (Na(+) and Cl(-)) are the major mass fraction (65%) of the total water-soluble matter followed by SO4(2-) (20%) and WSOM (6%). The seasonal variation of g(90%)ZSR was high in summer to autumn and low in winter to spring months, probably due to the influence of the long-range transport of anthropogenic SO4(2-), dust, and organics from East Asia and their interaction with sea-salts through heterogeneous reactions. On the other hand, annual variations of g(90%)ZSR showed a decrease from 2001 to 2006 and then an increase from 2007 to 2012. Interestingly, the annual variations in SO4(2-) mass fractions showed an increase from 2001 to 2006 and then a decrease from 2007 to 2012, demonstrating that SO4(2-) seriously suppresses the hygroscopic growth of sea-salt particles over the western North Pacific. This is further supported by the strong negative correlation between SO4(2-) and g(90%)ZSR. Based on the MODIS satellite data, the present study demonstrates that long-range transported anthropogenic pollutants from East Asia to the North Pacific can act as efficient cloud condensation nuclei but significantly suppress the precipitation by reducing the size of cloud droplets over the western North Pacific. PMID:26473178

  12. Deriving aerosol hygroscopic mixing state from size-resolved CCN activity and HR-ToF-AMS measurements

    NASA Astrophysics Data System (ADS)

    Bhattu, Deepika; Tripathi, S. N.; Chakraborty, Abhishek

    2016-10-01

    The ability of a particle to uptake water and form a cloud droplet depends on its hygroscopicity. To understand its impact on cloud properties and ultimately radiative forcing, knowledge of chemically-resolved mixing state information or the one based on hygroscopic growth is crucial. Typically, global models assume either pure internal or external mixing state which might not be true for all conditions and sampling locations. To investigate into this, the current study employed an indirect approach to infer the probable mixing state. The hygroscopic parameters derived from κ-Kohler theory using size-resolved CCN measurements (κCCN) and bulk/size-resolved aerosol mass spectrometer (AMS) measurements (κAMS) were compared. The accumulation mode particles were found to be more hygroscopic (κCCN = 0.24) than Aitken mode (κCCN = 0.13), perhaps due to increased ratio of inorganic to organic mass fraction. The activation diameter calculated from size-resolved CCN activity measurements at 5 different supersaturation (SS) levels varied in the range of 115 nm-42 nm with κCCN = 0.13-0.23 (avg = 0.18 ± 0.10 (±1σ)). Further, κAMS>κCCN was observed possibly due to the fact that organic and inorganic mass present in the Aitken mode was not correctly represented by bulk chemical composition and size-resolved fractional contribution of oxidized OA was not accurately accounted. Better correlation of organic fraction (forg) and κCCN at lower SS explained this behaviour. The decrease in κCCN with the time of the day was more pronounced at lower SS because of the relative mass reduction of soluble inorganic species by ∼17%. Despite the large differences between κ measured from two approaches, less over-prediction (up to 18%) between measured and predicted CCN concentration suggested lower impact of chemical composition and mixing state at higher SS. However, at lower SS, presences of externally mixed CCN-inactive aerosols lead to CCN over-prediction reflecting the

  13. In-cloud processes of methacrolein under simulated conditions - Part 3: Hygroscopic and volatility properties of the formed secondary organic aerosol

    NASA Astrophysics Data System (ADS)

    Michaud, V.; El Haddad, I.; Liu, Yao; Sellegri, K.; Laj, P.; Villani, P.; Picard, D.; Marchand, N.; Monod, A.

    2009-07-01

    The hygroscopic and volatility properties of secondary organic aerosol (SOA) produced from the nebulization of solutions after aqueous phase photooxidation of methacrolein was experimentally studied in a laboratory, using a Volatility-Hygroscopicity Tandem DMA (VHTDMA). The obtained SOA were 80% 100°C-volatile after 5 h of reaction and only 20% 100°C-volatile after 22 h of reaction. The Hygroscopic Growth Factor (HGF) of the SOA produced from the nebulization of solutions after aqueous-phase photooxidation of methacrolein is 1.34-1.43, which is significantly higher than the HGF of SOA formed by gas-phase photooxidation of terpenes, usually found almost hydrophobic. These hygroscopic properties were confirmed for SOA formed by the nebulization of the same solutions where NaCl was added. The hygroscopic properties of the cloud droplet residuals decrease with the reaction time, in parallel with the formation of more refractory compounds. This decrease was mainly attributed to the 250°C-refractive fraction (presumably representative of the highest molecular weight compounds), which evolved from moderately hygroscopic (HGF of 1.52) to less hygroscopic (HGF of 1.36). Oligomerization is suggested as a process responsible for the decrease of both volatility and hygroscopicity with time. The NaCl seeded experiments enabled us to show that 19±4 mg L-1 of SOA was produced after 9.5 h of reaction and 41±9 mg L-1 after 22 h of in-cloud reaction. Because more and more SOA is formed as the reaction time increases, our results show that the reaction products formed during the aqueous-phase OH-oxidation of methacrolein may play a major role in the properties of residual particles upon the droplet's evaporation. Therefore, the specific physical properties of SOA produced during cloud processes should be taken into account for a global estimation of SOA and their atmospheric impacts.

  14. Study of Aerosol Liquid Water Content based on Hygroscopicity Measurements at High Relative Humidity in the North China Plain

    NASA Astrophysics Data System (ADS)

    Bian, Y.; Zhao, C.

    2013-12-01

    Aerosol has significant effects on direct/indirect climate forcing, visibility, tropospheric chemistry and human health. Water can represent an extensive proportion of the mass of aerosol particles, and can also serve as a medium for aqueous-phase reactions in such particulate matter. In this study, a new method is proposed to estimate the aerosol liquid water content at high relative humidity, based on aerosol hygroscopic growth factors, particle number size distribution and relative humidity measured during the Haze in China (HaChi) campaign of July-August, 2009. The aerosol liquid water content estimated by this method is compared to the results calculated by a thermodynamic equilibrium model (ISORROPIA II). The calculation results from these two methods agree well at high relative humidity above 60% with the correlation coefficient of 0.9658. At relative humidity lower than 60%, the thermodynamic equilibrium model underestimates the aerosol liquid water content. The discrepancy is mainly caused by the ISORROPIA II model, which considers only limited chemical species. The mean and maximum value of aerosol liquid water content during July-August, 2009 in the North China Plain reached 1.69×10^{-4}g/m^3 and 9.71×10^{-4}g/m^3, respectively. Aerosol liquid water content is highly related to the relative humidity. There exists a distinct diurnal variation of the aerosol liquid water content, with lower values during daytime and higher ones during night time. The contribution to the aerosol liquid water content from the accumulation mode is dominating among all the aerosol particle modes.

  15. Interactions of Water with Mineral Dust Aerosol: Water Adsorption, Hygroscopicity, Cloud Condensation, and Ice Nucleation.

    PubMed

    Tang, Mingjin; Cziczo, Daniel J; Grassian, Vicki H

    2016-04-13

    Mineral dust aerosol is one of the major types of aerosol present in the troposphere. The molecular level interactions of water vapor with mineral dust are of global significance. Hygroscopicity, light scattering and absorption, heterogneous reactivity and the ability to form clouds are all related to water-dust interactions. In this review article, experimental techniques to probe water interactions with dust and theoretical frameworks to understand these interactions are discussed. A comprehensive overview of laboratory studies of water adsorption, hygroscopicity, cloud condensation, and ice nucleation of fresh and atmspherically aged mineral dust particles is provided. Finally, we relate laboratory studies and theoretical simulations that provide fundemental insights into these processes on the molecular level with field measurements that illustrate the atmospheric significance of these processes. Overall, the details of water interactions with mineral dust are covered from multiple perspectives in this review article. PMID:27015126

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

    NASA Astrophysics Data System (ADS)

    Tang, Ignatius N.

    1996-08-01

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

  17. Formation and aging of secondary organic aerosol from toluene: changes in chemical composition, volatility, and hygroscopicity

    DOE PAGESBeta

    Hildebrandt Ruiz, L.; Paciga, A. L.; Cerully, K. M.; Nenes, A.; Donahue, N. M.; Pandis, S. N.

    2015-07-24

    Secondary organic aerosol (SOA) is transformed after its initial formation, but this chemical aging of SOA is poorly understood. Experiments were conducted in the Carnegie Mellon environmental chamber to form secondary organic aerosol (SOA) from the photo-oxidation of toluene and other small aromatic volatile organic compounds (VOCs) in the presence of NOx under different oxidizing conditions. The effects of the oxidizing condition on organic aerosol (OA) composition, mass yield, volatility, and hygroscopicity were explored. Higher exposure to the hydroxyl radical resulted in different OA composition, average carbon oxidation state (OSc), and mass yield. The OA oxidation state generally increased duringmore » photo-oxidation, and the final OA OSc ranged from -0.29 to 0.16 in the performed experiments. The volatility of OA formed in these different experiments varied by as much as a factor of 30, demonstrating that the OA formed under different oxidizing conditions can have a significantly different saturation concentration. There was no clear correlation between hygroscopicity and oxidation state for this relatively hygroscopic SOA.« less

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

    PubMed

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

    2014-02-01

    A single horizontally-propagating zeroth order Bessel laser beam with a counter-propagating gas flow was used to confine single fine-mode aerosol particles over extended periods of time, during which process measurements were performed. Particle sizes were measured by the analysis of the angular variation of light scattered at 532 nm by a particle in the Bessel beam, using either a probe beam at 405 nm or 633 nm. The vapour pressures of glycerol and 1,2,6-hexanetriol particles were determined to be 7.5 ± 2.6 mPa and 0.20 ± 0.02 mPa respectively. The lower volatility of hexanetriol allowed better definition of the trapping environment relative humidity profile over the measurement time period, thus higher precision measurements were obtained compared to those for glycerol. The size evolution of a hexanetriol particle, as well as its refractive index at wavelengths 532 nm and 405 nm, were determined by modelling its position along the Bessel beam propagation length while collecting phase functions with the 405 nm probe beam. Measurements of the hygroscopic growth of sodium chloride and ammonium sulfate have been performed on particles as small as 350 nm in radius, with growth curves well described by widely used equilibrium state models. These are the smallest particles for which single-particle hygroscopicity has been measured and represent the first measurements of hygroscopicity on fine mode and near-accumulation mode aerosols, the size regimes bearing the most atmospheric relevance in terms of loading, light extinction and scattering. Finally, the technique is contrasted with other single particle and ensemble methods, and limitations are assessed. PMID:24346588

  19. Reduction in biomass burning aerosol light absorption upon humidification: Roles of inorganically-induced hygroscopicity, particle collapse, and photoacoustic heat and mass transfer

    SciTech Connect

    lewis, Kristen A.; Arnott, W. P.; Moosmuller, H.; Chakrabarti, Raj; Carrico, Christian M.; Kreidenweis, Sonia M.; Day, Derek E.; Malm, William C.; Laskin, Alexander; Jimenez, Jose L.; Ulbrich, Ingrid M.; Huffman, John A.; Onasch, Timothy B.; Trimborn, Achim; Liu, Li; Mishchenko, M.

    2009-11-27

    Smoke particle emissions from the combustion of biomass fuels typical for the western and southeastern United States were studied and compared under high humidity and ambient conditions in the laboratory. The fuels used are Montana ponderosa pine (Pinus ponderosa), southern California chamise (Adenostoma fasciculatum), and Florida saw palmetto (Serenoa repens). Information on the non-refractory chemical composition of biomass burning aerosol from each fuel was obtained with an aerosol mass spectrometer and through estimation of the black carbon concentration from light absorption measurements at 870 nm. Changes in the optical and physical particle properties under high humidity conditions were observed for hygroscopic smoke particles containing substantial inorganic mass fractions that were emitted from combustion of chamise and palmetto fuels. Light scattering cross sections increased under high humidity for these particles, consistent with the hygroscopic growth measured for 100 nm particles in HTDMA measurements. Photoacoustic measurements of aerosol light absorption coefficients reveal a 20% reduction with increasing relative humidity, contrary to the expectation of light absorption enhancement by the liquid coating taken up by hygroscopic particles. This reduction is hypothesized to arise from two mechanisms: 1. Shielding of inner monomers after particle consolidation or collapse with water uptake; 2. The contribution of mass transfer through evaporation and condensation at high relative humidity to the usual heat transfer pathway for energy release by laser heated particles in the photoacoustic measurement of aerosol light absorption. The mass transfer contribution is used to evaluate the fraction of aerosol surface covered with liquid water solution as a function of RH.

  20. Laboratory investigations of mixed organic/inorganic particles: Ice nucleation and optical hygroscopic growth

    NASA Astrophysics Data System (ADS)

    Beaver, Melinda R.

    The interactions of ambient aerosol particles with the atmosphere influence global climate and local visibility. Many of these atmospheric interactions are determined by the chemical composition of the aerosol particles. Ice nucleation in the upper troposphere is influenced and modified by the presence of anthropogenic aerosol particles. Also, interactions between particles and solar radiation are influenced by hygroscopic growth upon humidification. This thesis contains laboratory investigations into the role organic compounds play in ice nucleation and optical hygroscopic growth. Using an aerosol flow tube apparatus, we have studied the effects of aliphatic aldehydes (C3 to C10) and ketones (C 3 and C9) on ice nucleation in sulfuric acid aerosols. No acid-catalyzed reactions were observed under these conditions, and physical uptake was responsible for the organic content of the sulfuric acid aerosols. The physical properties of the organic compounds (primarily the solubility and melting point) were found to play a dominant role in determining the inferred mode of nucleation (homogenous or heterogeneous) and the specific freezing temperatures observed. Overall, very soluble, low-melting organics, such as acetone and propanal, caused a decrease in aerosol ice nucleation temperatures when compared with aqueous sulfuric acid aerosol. In contrast, sulfuric acid particles exposed to organic compounds of eight carbons and greater, of much lower solubility and higher melting temperatures, nucleate ice at temperatures above aqueous sulfuric acid aerosols. Organic compounds of intermediate carbon chain length, C4-C7, (of intermediate solubility and melting temperatures) nucleated ice at the same temperature as aqueous sulfuric acid aerosols. Light extinction by atmospheric particles is strongly dependent on the size, chemical composition, and water content of the aerosol. Since light extinction by particles directly impacts climate and visibility, measurements of

  1. Characterization of the Changes in Hygroscopicity of Ambient Organic Aerosol due to Oxidation by Gas Phase OH

    NASA Astrophysics Data System (ADS)

    Wong, J. P.; McWhinney, R. D.; Slowik, J. G.; Abbatt, J.

    2011-12-01

    Despite the ubiquitous nature of organic aerosols and their importance in climate forcing, the influence of chemical processes on their ability to act as cloud condensation nuclei (CCN) in the atmosphere remains uncertain. Changes to the hygroscopicity of ambient organic aerosol due to OH oxidation were explored at a remote forested (Whistler, British Columbia) and an urban (Toronto, Ontario) site. Organic aerosol was exposed to controlled levels of OH radicals in a portable flow tube reactor, the Toronto Photo-Oxidation Tube (TPOT). An Aerodyne Aerosol Mass Spectrometer (AMS) monitored the changes in the chemical composition due to OH-initiated oxidation. The CCN activity of size-selected particles was measured with a DMT Cloud Condensation Nuclei Counter (CCNc) to determine the hygroscopicity parameter, κ. Preliminary results suggest that gas phase OH oxidation increases the degree of oxygenation of organic aerosol, leading to increases in hygroscopicity. These results yield insights into the mechanism by which oxidation affects the hygroscopicity of ambient aerosol of various sources, and to constrain the main aging process that leads to the observation of increasing hygroscopicity with increasing oxidation of organic aerosol.

  2. Chemical closure study on hygroscopic properties of urban aerosol particles in Sapporo, Japan.

    PubMed

    Aggarwal, Shankar Gopala; Mochida, Michihiro; Kitamori, Yasuyuki; Kawamura, Kimitaka

    2007-10-15

    To assess the link between hygroscopicity of atmospheric particles and the chemical composition, we performed a chemical closure study on the hygroscopicity of organic-inorganic mixed particles nebulized from water extracts of ambient aerosols collected in Sapporo, Japan during summer 2005. The hygroscopicity of 100 nm particles was measured using a hygroscopicity tandem differential mobility analyzer (HTDMA) at 5-95% relative humidity. The chemical analyses of the extracts showed that inorganic salts accounted for 32-84% of the water-soluble fraction and that the remaining was water-soluble organic matter (WSOM). The liquid water content (LWC) of particles was primarily governed by the relative abundance of inorganic salts in particles. The chemical closure with a thermodynamic model did not indicate a significant perturbation of LWC by WSOM at 85% RH with the consideration of the uncertainties estimated. However, a positive perturbation by WSOM was suggested at 50% RH. Individual oxygenated compounds identified using gas chromatography were not abundant enough to substantially increase the LWC at 85% RH. PMID:17993129

  3. CCN Activity, Hygroscopicity, and Droplet Activation Kinetics of Secondary Organic Aerosol Resulting from the 2010 Gulf Oil Spill

    NASA Astrophysics Data System (ADS)

    Moore, R.; Lathem, T. L.; Cerully, K.; Bahreini, R.; Brock, C. A.; Langridge, J. M.; Middlebrook, A. M.; Nenes, A.; Calnex Science Team

    2010-12-01

    We present an analysis of the hygroscopicity and droplet activation kinetics of cloud condensation nuclei (CCN) sampled onboard the National Oceanic and Atmospheric Administration WP-3D aircraft downwind of the Deepwater Horizon oil spill site on June 8th and 10th, 2010. This set of measurements provides a unique case study for assessing in-situ the impact of fresh, hydrocarbonlike aerosols, which are expected to be formed via gas-to-particle conversion of the semi-volatile vapors released from oil evaporation. Similar hydrocarbon-rich aerosols constitute an important local emissions source in urban areas, but often coexist as an external/partially-internal mixture with more-oxidized, aged organic and sulfate aerosol. The DWH site provides the means to study the hygroscopic properties of these less-oxidized organic aerosols above a cleaner environmental background typical of marine environments in order to better discern their contribution to CCN activity and droplet growth. Measurements were performed with a Droplet Measurement Technologies Streamwise, Thermal-Gradient CCN counter, operating both as a counter (s=0.3%) and as a spectrometer (s=0.2-0.6%) using the newly-developed Scanning Flow CCN Analysis (SFCA) technique [1]. The instrument measures both the number concentration of particles able to nucleate droplets and also their resulting droplet sizes. The measured size information combined with a comprehensive computational fluid dynamics instrument model enables us to determine the rate of water uptake onto the particles and parameterize it in terms of an effective mass transfer coefficient [2], a key parameter needed to predict the number of activated droplets in ambient clouds. Non-refractory aerosol chemical composition was measured with an Aerodyne compact time-of-flight aerosol mass spectrometer. It was observed that the aerosols sampled downwind of the site on both days were composed predominantly of organics with a low degree of oxidation and low

  4. A humidity controlled Nephelometer system to study the hygroscopic properties of aerosols in the marine environment

    NASA Astrophysics Data System (ADS)

    Vaishya, Aditya; O'Dowd, Colin; Jennings, S. Gerard

    2010-05-01

    A Humidograph system has been designed to study the hygroscopic properties of aerosols for different air-masses and for different seasons in the marine environment. Since ambient marine aerosols are likely to be found in a metastable state, and in accordance with recommendations of WMO/GAW to sample dry aerosol, a drying unit (Nafion based) is placed just after the inlet to dry the aerosols to a relative humidity (RH) < 40% so as not to misinterpret the optical properties of hygroscopic aerosols if they are on the descending branch of the hysteresis curve. The flow after the dryer is split into two, one going to a 3-wavelength TSI-3563 Integrating Nephelometer, and the other to a Gore-Tex based humidifier followed by a single-wavelength TSI-3561 Integrating Nephelometer. The humidifier is used to vary the RH from 40% to 90%. While the TSI-3563 Integrating Nephelometer will operate at RH < 40%, the TSI-3561 Integrating Nephelometer will operate under varying RH conditions. Software developed in LabVIEW is used to control the hardware components and to log the data in a predefined format. Results of the performance of the Humidograph system in the laboratory and at the Mace Head Atmospheric Research Station are presented.

  5. Hygroscopicity Behavior, Activation Properties and Chemical Composition of Atmospheric Aerosol at a Background Site in the Megacity Region of Peking

    NASA Astrophysics Data System (ADS)

    Henning, Silvia; Nowak, Andreas; Mildenberger, Katrin; Göbel, Tina; Nekat, Bettina; van Pinxteren, Dominik; Herrmann, Hartmut; Zhao, Chunsheng; Wiedensohler, Alfred; Stratmann, Frank

    2010-05-01

    Large areas of China suffer from heavy air pollution (both gaseous and particulate) caused by strong economic growth in the last two decades. However, knowledge concerning the physical and chemical properties of the resulting aerosol particles populations, and their effects on the optical properties of the atmosphere, is still sparse. In the framework of the investigations presented here, comprehensive measurements concerning aerosol particle hygroscopicity, CCN ability, composition, and optical properties were performed. The investigations are part of the DFG-funded project HaChi (Haze in China) and are conducted in collaboration with the Peking University. A conclusive parameterization of aerosol hygroscopicity and activation data is aimed for, which will then be implemented in a meso-scale model to investigate aerosol-cloud-radiation and precipitation interactions. During two intensive measurements campaigns (March 2009 and July/ August 2009), in-situ aerosol measurements have been performed in an air-conditioned mobile laboratory next to the Wuqing Meteorological Station (39°23'8.53"N, 117°1'25.88"E), which is located between Bejing and Tijanjin and is thereby an ideal background site in a megacity region. The particle number size distribution (TDMPS), the particle optical properties (MAAP and nephelometer) and their hygroscopic properties at high RH (HH-TDMA, LACIS-mobile) were characterized as well as their cloud nucleating properties above supersaturation (DMT-CCNC). 24 h PM1 particle samples were continuously collected over the two campaigns in winter and summer using a DIGITEL high volume sampler (DHA-80). Additionally two 6h size-resolved samples (daytime and night-time) were collected each day applying an 11-stage Berner impactor. The size-selection of HH-TDMA, LACIS and the CCNC was synchronized with the Berner stages. Opening analysis of the winter campaign data showed that the HH-TDMA usually detected a hydrophobic and a hygroscopic mode, i.e., the

  6. Aerosolization, Chemical Characterization, Hygroscopicity and Ice Formation of Marine Biogenic Particles

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

    The oceans cover the majority of the earth's surface, host nearly half the total global primary productivity and are a major source of atmospheric aerosol particles. However, effects of biological activity on sea spray generation and composition, and subsequent cloud formation are not well understood. Our goal is to elucidate these effects which will be particularly important over nutrient rich seas, where microorganisms can reach concentrations of 10^9 per mL and along with transparent exopolymer particles (TEP) can become aerosolized. Here we report the results of mesocosm experiments in which bubbles were generated by two methods, either recirculating impinging water jets or glass frits, in natural or artificial seawater containing bacteria and unialgal cultures of three representative phytoplankton species, Thalassiosira pseudonana, Emiliania huxleyi, and Nannochloris atomus. Over time we followed the size distribution of aerosolized particles as well as their hygroscopicity, heterogeneous ice nucleation potential, and individual physical-chemical characteristics. Numbers of cells and the mass of dissolved and particulate organic carbon (DOC, POC), TEP (which includes polysaccharide-containing microgels and nanogels >0.4 μm in diameter) were determined in the bulk water, the surface microlayer, and aerosolized material. Aerosolized particles were also impacted onto substrates for ice nucleation and water uptake experiments, elemental analysis using computer controlled scanning electron microscopy and energy dispersive analysis of X-rays (CCSEM/EDX), and determination of carbon bonding with scanning transmission X-ray microscopy and near-edge X-ray absorption fine structure spectroscopy (STXM/NEXAFS). Regardless of bubble generation method, the overall concentration of aerosol particles, TEP, POC and DOC increased as concentrations of bacterial and phytoplankton cells increased, stabilized, and subsequently declined. Particles <100 nm generated by means of jets

  7. The effect of low solublility organic acids on the hygroscopicity of sodium halide aerosols

    NASA Astrophysics Data System (ADS)

    Miñambres, L.; Méndez, E.; Sánchez, M. N.; Castaño, F.; Basterretxea, F. J.

    2014-02-01

    In order to accurately assess the influence of fatty acids on the hygroscopic and other physicochemical properties of sea salt aerosols, hexanoic, octanoic or lauric acid together with sodium halide salts (NaCl, NaBr and NaI) have been chosen to be performed in this study. The hygroscopic properties of sodium halide submicrometer particles covered with organic acids have been examined by Fourier-transform infrared spectroscopy in an aerosol flow cell. Covered particles were generated by flowing atomized sodium halide particles (either dry or aqueous) through a heated oven containing the gaseous acid. The obtained results indicate that gaseous organic acids easily nucleate onto dry and aqueous sodium halide particles. On the other hand, Scanning Electron Microscopy (SEM) images indicate that lauric acid coating on NaCl particles makes them to aggregate in small clusters. The hygroscopic behaviour of covered sodium halide particles in deliquescence mode shows different features with the exchange of the halide ion: whereas the organic covering has little effect in NaBr particles, NaCl and NaI covered particles change their deliquescence relative humidities, with different trends observed for each of the acids studied. In efflorescence mode, the overall effect of the organic covering is to retard the loss of water in the particles. It has been observed that the presence of gaseous water in heterogeneously nucleated particles tends to displace the cover of hexanoic acid to energetically stabilize the system.

  8. The effect of low solubility organic acids on the hygroscopicity of sodium halide aerosols

    NASA Astrophysics Data System (ADS)

    Miñambres, L.; Méndez, E.; Sánchez, M. N.; Castaño, F.; Basterretxea, F. J.

    2014-10-01

    In order to accurately assess the influence of fatty acids on the hygroscopic and other physicochemical properties of sea salt aerosols, hexanoic, octanoic or lauric acid together with sodium halide salts (NaCl, NaBr and NaI) have been chosen to be investigated in this study. The hygroscopic properties of sodium halide sub-micrometre particles covered with organic acids have been examined by Fourier-transform infrared spectroscopy in an aerosol flow cell. Covered particles were generated by flowing atomized sodium halide particles (either dry or aqueous) through a heated oven containing the gaseous acid. The obtained results indicate that gaseous organic acids easily nucleate onto dry and aqueous sodium halide particles. On the other hand, scanning electron microscopy (SEM) images indicate that lauric acid coating on NaCl particles makes them to aggregate in small clusters. The hygroscopic behaviour of covered sodium halide particles in deliquescence mode shows different features with the exchange of the halide ion, whereas the organic surfactant has little effect in NaBr particles, NaCl and NaI covered particles experience appreciable shifts in their deliquescence relative humidities, with different trends observed for each of the acids studied. In efflorescence mode, the overall effect of the organic covering is to retard the loss of water in the particles. It has been observed that the presence of gaseous water in heterogeneously nucleated particles tends to displace the cover of hexanoic acid to energetically stabilize the system.

  9. Chemical composition, microstructure, and hygroscopic properties of aerosol particles at the Zotino Tall Tower Observatory (ZOTTO), Siberia, during a summer campaign

    DOE PAGESBeta

    Mikhailov, E. F.; Mironov, G. N.; Pöhlker, C.; Chi, X.; Krüger, M. L.; Shiraiwa, M.; Förster, J. -D.; Pöschl, U.; Vlasenko, S. S.; Ryshkevich, T. I.; et al

    2015-03-16

    In this study we describe the hygroscopic properties of accumulation- and coarse-mode aerosol particles sampled at the Zotino Tall Tower Observatory (ZOTTO) in Central Siberia (61° N; 89° E) from 16 to 21 June 2013. The hygroscopic growth measurements were supplemented with chemical analyses of the samples, including inorganic ions and organic/elemental carbon. In addition, the microstructure and chemical composition of aerosol particles were analyzed by X-ray micro-spectroscopy (STXM-NEXAFS) and transmission electron microscopy (TEM). A mass closure analysis indicates that organic carbon accounted for 61 and 38% of PM in the accumulation mode and coarse mode, respectively. The water solublemore » fraction of organic matter was estimated to be 52 and 8% of PM in these modes. Sulfate, predominantly in the form of ammoniated sulfate, was the dominant inorganic component in both size modes: ~ 34% in the accumulation vs. ~ 47% in the coarse mode. The hygroscopic growth measurements were conducted with a filter-based differential hygroscopicity analyzer (FDHA) over the range of 5–99.4% RH in the hydration and dehydration operation modes. The FDHA study indicates that both accumulation and coarse modes exhibit pronounced water uptake approximately at the same RH, starting at ~ 70%, while efflorescence occurred at different humidities, i.e., at ~ 35% RH for submicron particles vs. ~ 50% RH for supermicron particles. This ~ 15% RH difference was attributed to higher content of organic material in the submicron particles, which suppresses water release in the dehydration experiments. The kappa mass interaction model (KIM) was applied to characterize and parameterize non-ideal solution behavior and concentration-dependent water uptake by atmospheric aerosol samples in the 5–99.4% RH range. Based on KIM, the volume-based hygroscopicity parameter, κv, was calculated. The κv, ws value related to the water soluble (ws) fraction was estimated to be ~ 0.15 for the

  10. Chemical composition, microstructure, and hygroscopic properties of aerosol particles at the Zotino Tall Tower Observatory (ZOTTO), Siberia, during a summer campaign

    NASA Astrophysics Data System (ADS)

    Mikhailov, E. F.; Mironov, G. N.; Pöhlker, C.; Chi, X.; Krüger, M. L.; Shiraiwa, M.; Förster, J.-D.; Pöschl, U.; Vlasenko, S. S.; Ryshkevich, T. I.; Weigand, M.; Kilcoyne, A. L. D.; Andreae, M. O.

    2015-03-01

    In this study we describe the hygroscopic properties of accumulation- and coarse-mode aerosol particles sampled at the Zotino Tall Tower Observatory (ZOTTO) in Central Siberia (61° N; 89° E) from 16 to 21 June 2013. The hygroscopic growth measurements were supplemented with chemical analyses of the samples, including inorganic ions and organic/elemental carbon. In addition, the microstructure and chemical composition of aerosol particles were analyzed by X-ray micro-spectroscopy (STXM-NEXAFS) and transmission electron microscopy (TEM). A mass closure analysis indicates that organic carbon accounted for 61 and 38% of PM in the accumulation mode and coarse mode, respectively. The water soluble fraction of organic matter was estimated to be 52 and 8% of PM in these modes. Sulfate, predominantly in the form of ammoniated sulfate, was the dominant inorganic component in both size modes: ∼34% in the accumulation vs. ∼47% in the coarse mode. The hygroscopic growth measurements were conducted with a filter-based differential hygroscopicity analyzer (FDHA) over the range of 5-99.4% RH in the hydration and dehydration operation modes. The FDHA study indicates that both accumulation and coarse modes exhibit pronounced water uptake approximately at the same RH, starting at ∼70%, while efflorescence occurred at different humidities, i.e., at ∼35% RH for submicron particles vs. ∼50% RH for supermicron particles. This ∼15% RH difference was attributed to higher content of organic material in the submicron particles, which suppresses water release in the dehydration experiments. The kappa mass interaction model (KIM) was applied to characterize and parameterize non-ideal solution behavior and concentration-dependent water uptake by atmospheric aerosol samples in the 5-99.4% RH range. Based on KIM, the volume-based hygroscopicity parameter, κv, was calculated. The κv, ws value related to the water soluble (ws) fraction was estimated to be ∼0.15 for

  11. Chemical composition, microstructure, and hygroscopic properties of aerosol particles at the Zotino Tall Tower Observatory (ZOTTO), Siberia, during a summer campaign

    NASA Astrophysics Data System (ADS)

    Mikhailov, E. F.; Mironov, G. N.; Pöhlker, C.; Chi, X.; Krüger, M. L.; Shiraiwa, M.; Förster, J.-D.; Pöschl, U.; Vlasenko, S. S.; Ryshkevich, T. I.; Weigand, M.; Kilcoyne, A. L. D.; Andreae, M. O.

    2015-08-01

    In this study we describe the hygroscopic properties of accumulation- and coarse-mode aerosol particles sampled at the Zotino Tall Tower Observatory (ZOTTO) in central Siberia (61° N, 89° E) from 16 to 21 June 2013. The hygroscopic growth measurements were supplemented with chemical analyses of the samples, including inorganic ions and organic/elemental carbon. In addition, the microstructure and chemical compositions of aerosol particles were analyzed by x-ray micro-spectroscopy (STXM-NEXAFS) and transmission electron microscopy (TEM). A mass closure analysis indicates that organic carbon accounted for 61 and 38 % of particulate matter (PM) in the accumulation mode and coarse mode, respectively. The water-soluble fraction of organic matter was estimated to be 52 and 8 % of PM in these modes. Sulfate, predominantly in the form of ammoniated sulfate, was the dominant inorganic component in both size modes: ~ 34 % in the accumulation mode vs. ~ 47 % in the coarse mode. The hygroscopic growth measurements were conducted with a filter-based differential hygroscopicity analyzer (FDHA) over the range of 5-99.4 % RH in the hydration and dehydration operation modes. The FDHA study indicates that both accumulation and coarse modes exhibit pronounced water uptake approximately at the same relative humidity (RH), starting at ~ 70 %, while efflorescence occurred at different humidities, i.e., at ~ 35 % RH for submicron particles vs. ~ 50 % RH for supermicron particles. This ~ 15 % RH difference was attributed to higher content of organic material in the submicron particles, which suppresses water release in the dehydration experiments. The kappa mass interaction model (KIM) was applied to characterize and parameterize non-ideal solution behavior and concentration-dependent water uptake by atmospheric aerosol samples in the 5-99.4 % RH range. Based on KIM, the volume-based hygroscopicity parameter, κv, was calculated. The κv,ws value related to the water-soluble (ws

  12. Competing effects of viscosity and surface-tension depression on the hygroscopicity and CCN activity of laboratory surrogates for oligomers in atmospheric aerosol

    NASA Astrophysics Data System (ADS)

    Hodas, N.; Zuend, A.; Shiraiwa, M.; Flagan, R. C.; Seinfeld, J.; Schilling, K.; Berkemeier, T.

    2015-12-01

    The presence of oligomers in biomass burning aerosol, as well as secondary organic aerosol derived from other sources, influences particle viscosity and can introduce kinetic limitations to water uptake. This, in turn, impacts aerosol optical properties and the efficiency with which these particles serve as cloud condensation nuclei (CCN). To explore the influence of organic-component viscosity on aerosol hygroscopicity, the water-uptake behavior of aerosol systems comprised of polyethylene glycol (PEG) and mixtures of PEG and ammonium sulfate (AS) was measured under sub- and supersaturated relative humidity (RH) conditions. Experiments were conducted with systems containing PEG with average molecular weights ranging from 200 to 10,000 g/mol, corresponding to a range in viscosity of 0.004 - 4.5 Pa s under dry conditions. While evidence suggests that viscous aerosol components can suppress water uptake at RH < 90%, under supersaturated conditions (with respect to RH), an increase in CCN activity with increasing PEG molecular weight was observed. We attribute this to an increase in the efficiency with which PEG serves as a surfactant with increasing molecular weight. This effect is most pronounced for PEG-AS mixtures and, in fact, a modest increase in CCN activity is observed for the PEG 10,000-AS mixture as compared to pure AS, as evidenced by a 4% reduction in critical activation diameter. Experimental results are compared with calculations of hygroscopic growth at thermodynamic equilibrium using the Aerosol Inorganic-Organic Mixtures Functional groups Activity Coefficients model and the potential influence of kinetic limitations to observed water uptake is further explored with the Kinetic Multi-Layer Model of Gas-Particle Interactions. Results suggest the competing effects of organic-component viscosity and surface-tension depression may lead to RH-dependent differences in hygroscopicity for oligomers and other surface-active compounds present in atmospheric

  13. In-Situ Measurements of Aerosol Optical and Hygroscopic Properties at the Look Rock Site during SOAS 2013

    NASA Astrophysics Data System (ADS)

    Zhang, X.; Zimmermann, K.; Bertram, T. H.; Corrigan, A. L.; Guzman, J. M.; Russell, L. M.; Budisulistiorini, S.; Li, X.; Surratt, J. D.; Hicks, W.; Bairai, S. T.; Cappa, C. D.

    2013-12-01

    One of the main goals of the Southern Oxidant and Aerosol Study (SOAS) is to characterize the climate-relevant properties of aerosols over the southeastern United States at the interface of biogenic and anthropogenic emissions. As part of the SOAS campaign, the UCD cavity ringdown/photoacoustic spectrometer was deployed to make in-situ measurements of aerosol light extinction, absorption and sub-saturated hygroscopicity at the Look Rock site (LRK) in the Great Smoky Mountains National Park, TN from June 1 to July 15, 2013. The site is influenced by substantial biogenic emissions with varying impacts from anthropogenic pollutants, allowing for direct examination of the optical and hygroscopic properties of anthropogenic-influenced biogenic secondary organic aerosols (SOA). During the experiment period, the average dry aerosol extinction (Bext), absorption (Babs) coefficients and single scattering albedo (SSA) at 532 nm were 30.3 × 16.5 Mm-1, 1.12 × 0.78 Mm-1 and 0.96 × 0.06. The Babs at 532 nm was well correlated (r2 = 0.79) with the refractory black carbon (rBC) number concentration determined by a single particle soot spectrometer (SP2). The absorption by black carbon (BC), brown carbon (BrC) and the absorption enhancement due to the 'lensing' effect were quantified by comparing the Babs of ambient and thermo-denuded aerosols at 405 nm and 532 nm. The optical sub-saturated hygroscopic growth factor was derived from extinction and particle size distribution measurements at dry and elevated relative humidity. In addition, to explore the extent to which ammonia mediated chemistry leads to BrC formation, as suggested in recent laboratory studies(1,2), we performed an NH3 perturbation experiment in-situ for 1 week during the study, in which ambient aerosols were exposed to approximately 100 ppb NH3 with a residence time of ~ 3hr. The broader implications of these observational data at LRK will be discussed in the context of the concurrent gas and aerosol chemical

  14. AMS Measurements in National Parks of Aerosol Mass, Size and Composition, Comparison with Filter Samples and Correlation with Particle Hygroscopicity and Optical Extinction Properties

    NASA Astrophysics Data System (ADS)

    Alexander, M.; Taylor, N. F.; Collins, D. R.; Kumar, N.; Allen, J.; Newburn, M.; Lowenthal, D. H.; Zielinska, B.

    2011-12-01

    We report a comparison of results from aerosol studies at Great Smoky Mountain National Park (2006), Mt. Rainier National Park (2009) and Acadia National Park (2011), all class I visibility areas associated with IMPROVE (Interagency Monitoring of Protected Visual Environments) sites. This collaborative study was sponsored by the Electric Power Research Institute (EPRI) and was done with the cooperation of the National Park Service and the EPA. The atmospheric aerosol composition in these sites is influenced by a number of anthropogenic as well as biogenic sources, providing a rich environment for fundamental aerosol studies. The primary purpose of these studies was to add state-of-the-art aerosol instrumentation to the standard light extinction and aerosol measurements at the site, used to determine parameters for the IMPROVE light extinction reconstruction equation, adopted by the EPA to estimate light extinction from atmospheric aerosol concentrations and Rayleigh scattering. The combination of these diverse measurements also provides significant insight into fundamental aerosol properties such as aging and radiative forcing. New instrumentation included a quadrupole aerosol mass spectrometer (Aerodyne Q-AMS-Smoky Mountain Study), a high resolution aerosol time-of-flight mass spectrometer (Aerodyne HR-ToF-AMS - Mt. Rainier and Acadia studies) for real time measurements that directly address the relationship between sulfate, nitrate, and OC size and concentration, which is related to cloud and dry gas-to-particle conversion as air masses age during transport, the relationship between WSOC hygroscopic growth and oxygenated organic (OOA) composition, the OCM/OC ratio, and the chemical composition that determines the ambient hygroscopic state. The OCM/OC ratio and organic water uptake was addressed with high-volume and medium volume PM2.5 aerosol samples. Aerosols were collected daily on Teflon coated glass fiber filters (TGFF) in four high-volume PM2.5 samplers

  15. Organic component vapor pressures and hygroscopicities of aqueous aerosol measured by optical tweezers.

    PubMed

    Cai, Chen; Stewart, David J; Reid, Jonathan P; Zhang, Yun-hong; Ohm, Peter; Dutcher, Cari S; Clegg, Simon L

    2015-01-29

    Measurements of the hygroscopic response of aerosol and the particle-to-gas partitioning of semivolatile organic compounds are crucial for providing more accurate descriptions of the compositional and size distributions of atmospheric aerosol. Concurrent measurements of particle size and composition (inferred from refractive index) are reported here using optical tweezers to isolate and probe individual aerosol droplets over extended timeframes. The measurements are shown to allow accurate retrievals of component vapor pressures and hygroscopic response through examining correlated variations in size and composition for binary droplets containing water and a single organic component. Measurements are reported for a homologous series of dicarboxylic acids, maleic acid, citric acid, glycerol, or 1,2,6-hexanetriol. An assessment of the inherent uncertainties in such measurements when measuring only particle size is provided to confirm the value of such a correlational approach. We also show that the method of molar refraction provides an accurate characterization of the compositional dependence of the refractive index of the solutions. In this method, the density of the pure liquid solute is the largest uncertainty and must be either known or inferred from subsaturated measurements with an error of <±2.5% to discriminate between different thermodynamic treatments. PMID:25522920

  16. Aerosol hygroscopicity and CCN activity during the AC3Exp campaign: Implications for CCN parameterization

    NASA Astrophysics Data System (ADS)

    Zhang, Fang; Li, Yanan; Li, Zhanqing

    2015-04-01

    Atmospheric aerosol particles acting as CCN are pivotal elements of the hydrological cycle and climate change. In this study, we measured and characterized NCCN in relatively clean and polluted air during the AC3Exp campaign conducted at Xianghe, China during summer 2013. The aim was to examine CCN activation properties under high aerosol loading conditions in a polluted region and to assess the impacts of particle size and chemical composition on the CCN AR which acts as a proxy of the total number of aerosol particles in the atmosphere. A gradual increase in size-resolved AR with particle diameter suggests that aerosol particles have different hygroscopicities. For particles in the accumulation mode, values of κapa range from 0.31-0.38 under background conditions, which is about 20% higher than that derived under polluted conditions. For particles in the nucleation or Aitken mode, κ range from 0.20-0.34 under both background and polluted conditions. Larger particles were on average more hygroscopic than smaller particles. However, the case is more complex for particles originating from heavy pollution due to the diversity in particle composition and mixing state. The low R2 for the NPO CCN closure test suggests a 30%-40% uncertainty in total NCCN estimation. Using bulk chemical composition data from ACSM measurements, the relationship between bulk AR and the physical and chemical properties of atmospheric aerosols is investigated. Based on a case study, it has been concluded that one cannot use a parameterized formula using only total NCN to estimate total NCCN. Our results showed a possibility of using bulk κchem and f44 in combination with bulk NCN > 100 nm to parameterize CCN number concentrations.

  17. Ambient sulfate aerosol deposition in man: modeling the influence of hygroscopicity.

    PubMed Central

    Martonen, T B; Barnett, A E; Miller, F J

    1985-01-01

    Atmospheric sulfate aerosols [H2SO4, (NH4)2SO4, and NH4HSO4] are of international concern because of their global prevalence and potential irritant or toxic effects on humans. To assess hazards following inhalation exposure, the total dose delivered to the human respiratory tract and its regional distribution must be determined. The mass median aerodynamic diameter of the inhaled aerosol will influence the sites of deposition in the respiratory tract. Atmospheric sulfate aerosols are hygroscopic and will have changing particle sizes and densities as they absorb water vapor in the humid environment of the human respiratory tract. Experimental and theoretical data that describe particle size as a function of temperature and relative humidity were used in computer subroutines of an aerosol deposition model in order to calculate the dose dispersion of H2SO4, (NH4)2SO4, and NH4HSO4 aerosols in man. Different temperature and relative humidity environments that approximately correspond to nasal and oral breathing were studied. The predicted deposition patterns are very different from those of nonhygroscopic aerosols with identical inhaled mass median aerodynamic diameter values. PMID:4076076

  18. Airborne characterization of subsaturated aerosol hygroscopicity and dry refractive index from the surface to 6.5 km during the SEAC4RS campaign

    NASA Astrophysics Data System (ADS)

    Shingler, Taylor; Crosbie, Ewan; Ortega, Amber; Shiraiwa, Manabu; Zuend, Andreas; Beyersdorf, Andreas; Ziemba, Luke; Anderson, Bruce; Thornhill, Lee; Perring, Anne E.; Schwarz, Joshua P.; Campazano-Jost, Pedro; Day, Douglas A.; Jimenez, Jose L.; Hair, Johnathan W.; Mikoviny, Tomas; Wisthaler, Armin; Sorooshian, Armin

    2016-04-01

    In situ aerosol particle measurements were conducted during 21 NASA DC-8 flights in the Studies of Emissions and Atmospheric Composition, Clouds, and Climate Coupling by Regional Surveys field campaign over the United States, Canada, Pacific Ocean, and Gulf of Mexico. For the first time, this study reports rapid, size-resolved hygroscopic growth and real refractive index (RI at 532 nm) data between the surface and upper troposphere in a variety of air masses including wildfires, agricultural fires, biogenic, marine, and urban outflow. The Differential Aerosol Sizing and Hygroscopicity Spectrometer Probe (DASH-SP) quantified size-resolved diameter growth factors (GF = Dp,wet/Dp,dry) that are used to infer the hygroscopicity parameter κ. Thermokinetic simulations were conducted to estimate the impact of partial particle volatilization within the DASH-SP across a range of sampling conditions. Analyses of GF and RI data as a function of air mass origin, dry size, and altitude are reported, in addition to κ values for the inorganic and organic fractions of aerosol. Average RI values are found to be fairly constant (1.52-1.54) for all air mass categories. An algorithm is used to compare size-resolved DASH-SP GF with bulk scattering f(RH = 80%) data obtained from a pair of nephelometers, and the results show that the two can only be reconciled if GF is assumed to decrease with increasing dry size above 400 nm (i.e., beyond the upper bound of DASH-SP measurements). Individual case studies illustrate variations of hygroscopicity as a function of dry size, environmental conditions, altitude, and composition.

  19. Changes in droplet surface tension affect the observed hygroscopicity of photochemically aged biomass burning aerosol.

    PubMed

    Giordano, Michael R; Short, Daniel Z; Hosseini, Seyedehsan; Lichtenberg, William; Asa-Awuku, Akua A

    2013-10-01

    This study examines the hygroscopic and surface tension properties as a function of photochemical aging of the aerosol emissions from biomass burning. Experiments were conducted in a chamber setting at the UC-Riverside Center for Environmental Research and Technology (CE-CERT) Atmospheric Processes Lab using two biomass fuel sources, manzanita and chamise. Cloud condensation nuclei (CCN) measurements and off-line filter sample analysis were conducted. The water-soluble organic carbon content and surface tension of the extracted filter samples were measured. Surface tension information was then examined with Köhler theory analysis to calculate the hygroscopicity parameter, κ. Laboratory measurement of biomass burning smoke from two chaparral fuels is shown to depress the surface tension of water by 30% or more at organic matter concentrations relevant at droplet activation. Accounting for surface tension depression can lower the calculated κ by a factor of 2. This work provides evidence for surface tension depression in an important aerosol system and may provide closure for differing sub- and supersaturated κ measurements. PMID:23957441

  20. Hygroscopic properties of large aerosol particles using the example of aged Saharan mineral dust - a semi-automated electron microscopy approach

    NASA Astrophysics Data System (ADS)

    Hartmann, Markus; Heim, Lars-Oliver; Ebert, Martin; Weinbruch, Stephan; Kandler, Konrad

    2015-04-01

    Hygroscopic properties of large aerosol particles using the example of aged Saharan mineral dust - a semi-automated electron microscopy approach Markus Hartmann(1), Lars-Oliver Heim(2), Martin Ebert(1), Stephan Weinbruch(1), Konrad Kandler(1) The Saharan Aerosol Long-range Transport and Aerosol-Cloud-Interaction Experiment (SALTRACE) took place at Barbados from June 10 to July 15 2013. During this period, dust was frequently transported from Africa across the Atlantic Ocean toward the Caribbean. In this study, we investigate the atmospheric aging of the dust aerosol based on its hygroscopicity. Aerosol samples were collected ground-based at Ragged Point (13°9'54.4"N, 59°25'55.7"W) with a single round jet cascade impactor on nickel-substrates. The particles from the stage with a 50% efficiency cutoff size of 1 µm were analyzed with an Environmental Scanning Electron Microscope (ESEM) equipped with an energy-dispersive X-ray detector (EDX) and a cooling stage. In an initial automated run, information on particle size and chemical composition for elements heavier than carbon were gathered. Afterwards, electron microscope images of the same sample areas as before were taken during a stepwise increase of relative humidities (between 50 % and 92%), so that the hygroscopic growth of the droplets could be directly observed. The observed hygroscopic growth can be correlated to the chemical composition of the respective particles. For the automated analysis of several hundred images of droplets an image processing algorithm in Python was developed. The algorithm is based on histogram equalization and watershed segmentation. Since SEM images can only deliver two-dimensional information, but the hygroscopic growth factor usually refers to the volume of a drop, Atomic Force Microscopy (AFM) was used to derive an empirical function for the drop volume depending on the apparent drop diameter in the electron images. Aside from the mineral dust, composed of mostly silicates and

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

  2. 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.

  3. Hygroscopic properties and extinction of aerosol particles at ambient relative humidity in South-Eastern China

    NASA Astrophysics Data System (ADS)

    Eichler, H.; Cheng, Y. F.; Birmili, W.; Nowak, A.; Wiedensohler, A.; Brüggemann, E.; Gnauk, T.; Herrmann, H.; Althausen, D.; Ansmann, A.; Engelmann, R.; Tesche, M.; Wendisch, M.; Zhang, Y. H.; Hu, M.; Liu, S.; Zeng, L. M.

    During the "Program of Regional Integrated Experiments of Air Quality over Pearl River Delta 2004 (PRIDE-PRD2004)" hygroscopic properties of particles in the diameter range 22 nm to 10μm were determined. For that purpose, a Humidifying Differential Mobility Particle Sizer (H-DMPS) and a Micro-Orifice Uniform Deposition Impactor (MOUDI) were operated. The derived size-dependent particle hygroscopic growth factors were interpolated to ambient relative humidity (RH) and used to calculate the particle number size distributions (PNSDs) at ambient conditions. A comparison between the modeled particle extinction coefficients (σ) and those observed with a Raman lidar was made. It is shown that the particle extinction coefficient ( σext) at ambient RH can be properly estimated with Mie-model calculations based on the in situ physico-chemical measurements of dry and humidified PNSD and chemical composition.

  4. Low hygroscopic scattering enhancement of boreal aerosol and the implications for a columnar optical closure study

    NASA Astrophysics Data System (ADS)

    Zieger, P.; Aalto, P. P.; Aaltonen, V.; Äijälä, M.; Backman, J.; Hong, J.; Komppula, M.; Krejci, R.; Laborde, M.; Lampilahti, J.; de Leeuw, G.; Pfüller, A.; Rosati, B.; Tesche, M.; Tunved, P.; Väänänen, R.; Petäjä, T.

    2015-07-01

    Ambient aerosol particles can take up water and thus change their optical properties depending on the hygroscopicity and the relative humidity (RH) of the surrounding air. Knowledge of the hygroscopicity effect is of crucial importance for radiative forcing calculations and is also needed for the comparison or validation of remote sensing or model results with in situ measurements. Specifically, particle light scattering depends on RH and can be described by the scattering enhancement factor f(RH), which is defined as the particle light scattering coefficient at defined RH divided by its dry value (RH <30-40 %). Here, we present results of an intensive field campaign carried out in summer 2013 at the SMEAR II station at Hyytiälä, Finland. Ground-based and airborne measurements of aerosol optical, chemical and microphysical properties were conducted. The f(RH) measured at ground level by a humidified nephelometer is found to be generally lower (e.g. 1.63±0.22 at RH = 85 % and λ = 525 nm) than observed at other European sites. One reason is the high organic mass fraction of the aerosol encountered at Hyytiälä to which f(RH) is clearly anti-correlated (R2≈0.8). A simplified parametrization of f(RH) based on the measured chemical mass fraction can therefore be derived for this aerosol type. A trajectory analysis revealed that elevated values of f(RH) and the corresponding elevated inorganic mass fraction are partially caused by transported hygroscopic sea spray particles. An optical closure study shows the consistency of the ground-based in situ measurements. Our measurements allow to determine the ambient particle light extinction coefficient using the measured f(RH). By combining the ground-based measurements with intensive aircraft measurements of the particle number size distribution and ambient RH, columnar values of the particle extinction coefficient are determined and compared to columnar measurements of a co-located AERONET sun photometer. The water

  5. Seasonal behavior of PM2.5 deliquescence, crystallization, and hygroscopic growth in the Po Valley (Milan): Implications for remote sensing applications

    NASA Astrophysics Data System (ADS)

    D'Angelo, Luca; Rovelli, Grazia; Casati, Marco; Sangiorgi, Giorgia; Perrone, Maria Grazia; Bolzacchini, Ezio; Ferrero, Luca

    2016-07-01

    Atmospheric aerosols deliquescence and crystallization relative humidity (DRH and CRH) are rarely measured compared to the worldwide number of hygroscopicity measurements; this feature comes from the lack of an efficient method able to capture the whole complexity of chemical composition of aerosols. Despite this, the knowledge of both DRH and CRH are crucial for a correct parameterization of the aerosol hygroscopic growth used in different applications, among which the remote sensing is very important. In this paper, a newly developed technique (direct current conductance method) was applied in an aerosol chamber to Milan PM2.5 samples, to identify aerosol DRH and CRH both during winter and summer. These results were compared with those independently obtained by gravimetric measurements conducted in the chamber using a microbalance. Microbalance data allowed also the determination of the mass hygroscopic growth factor on the collected PM2.5 samples. Results evidenced first a good agreement between the two methods (RMSE = 2.7% and 2.3% for DRH and CRH, respectively). Collected data evidenced the hysteresis behavior of ambient particles and variability in both DRH and CRH between the two seasons. Summer samples showed higher DRH and CRH (on average 71.4 ± 1.0% RH and 62.6 ± 1.2% RH, respectively) than the winter ones (on average 55.2 ± 0.7% RH and 46.9 ± 0.6% RH). This behavior was related to the higher content of sulfates during the summer season. Conversely, the mass hygroscopic growth factor at 90% RH was higher for winter samples (2.76 ± 0.06) with respect to the summer ones (1.91 ± 0.11). Since hysteresis behavior affects optical properties of aerosols, when RH conditions are within the loop, the hygroscopic growth factor could be assigned in a wrong way. Thus, the growth factor was calculated within the hysteresis loop for both upper and lower branches: results showed that difference in hygroscopic growth factor could reach up the 24%.

  6. The Effects of Mineral Dust on the Hygroscopic and Optical Properties of Inorganic Salt Aerosols

    NASA Astrophysics Data System (ADS)

    Attwood, A. R.; Greenslade, M. E.

    2011-12-01

    Mineral dust particles are a significant fraction of the total aerosol mass, thus they play an important role in the Earth's radiative budget by direct scattering and absorption of radiation. Assessing this impact is complicated by the variability of optical properties resulting from water uptake and changes in chemical composition due to atmospheric mixing. Internal mixtures of montmorillonite, a clay component of mineral dust, with sodium chloride and ammonium sulfate were studied optically using cavity ring down spectroscopy. The effects of the addition of the clay to the optically observed deliquescence relative humidity (DRH) and water uptake of these salts was considered by investigating a series of different salt mass fractions. In most cases, montmorillonite alters the hygroscopic properties and causes the DRH to occur at a lower relative humidity. For ammonium sulfate, optical properties can be approximated by volume weighted mixing rules with some minor deviations around the DRH. For sodium chloride, this approximation is only accurate below the DRH with enhanced water uptake at higher relative humidities. Our results show that salt particles may transition from solid to liquid at a lower relative humidity than is expected based on the salt alone, as observed with changes in optical properties. Further, they contradict current measurements in the literature that suggest little change in the hygroscopic behavior of salts when insoluble mineral dust components are added and should continue to be investigated. Accurate, direct measurements of the effect of the addition of clays to the optical properties of common aerosol species will allow for improvements in the prediction of the aerosol direct effect.

  7. Numerical investigation of the coagulation mixing between dust and hygroscopic aerosol particles and its impacts

    NASA Astrophysics Data System (ADS)

    Tsai, I.-Chun; Chen, Jen-Ping; Lin, Yi-Chiu; Chung-Kuang Chou, Charles; Chen, Wei-Nai

    2015-05-01

    A statistical-numerical aerosol parameterization was incorporated into the Community Multiscale Air Quality modeling system to study the coagulation mixing process focusing on a dust storm event that occurred over East Asia. Simulation results show that the coagulation mixing process tends to decrease aerosol mass, surface area, and number concentrations over the dust source areas. Over the downwind oceanic areas, aerosol concentrations generally increased due to enhanced sedimentation as particles became larger upon coagulation. The mixture process can reduce the overall single-scattering albedo by up to 10% as a result of enhanced core with shell absorption by dust and reduction in the number of scattering particles. The enhanced dry deposition speed also altered the vertical distribution. In addition, the ability of aerosol particles to serve as cloud condensation nuclei (CCN) increased from around 107 m-3 to above 109 m-3 over downwind areas because a large amount of mineral dust particles became effective CCN with solute coating, except over the highly polluted areas where multiple collections of hygroscopic particles by dust in effect reduced CCN number. This CCN effect is much stronger for coagulation mixing than by the uptake of sulfuric acid gas on dust, although the nitric acid gas uptake was not investigated. The ability of dust particles to serve as ice nuclei may decrease or increase at low or high subzero temperatures, respectively, due to the switching from deposition nucleation to immersion freezing or haze freezing.

  8. Laboratory Studies of Processing of Carbonaceous Aerosols by Atmospheric Oxidants/Hygroscopicity and CCN Activity of Secondary & Processed Primary Organic Aerosols

    SciTech Connect

    Ziemann, P.J.; Arey, J.; Atkinson, R.; Kreidenweis, S.M.; Petters, M.D.

    2012-06-13

    The atmosphere is composed of a complex mixture of gases and suspended microscopic aerosol particles. The ability of these particles to take up water (hygroscopicity) and to act as nuclei for cloud droplet formation significantly impacts aerosol light scattering and absorption, and cloud formation, thereby influencing air quality, visibility, and climate in important ways. A substantial, yet poorly characterized component of the atmospheric aerosol is organic matter. Its major sources are direct emissions from combustion processes, which are referred to as primary organic aerosol (POA), or in situ processes in which volatile organic compounds (VOCs) are oxidized in the atmosphere to low volatility reaction products that subsequent condense to form particles that are referred to as secondary organic aerosol (SOA). POA and VOCs are emitted to the atmosphere from both anthropogenic and natural (biogenic) sources. The overall goal of this experimental research project was to conduct laboratory studies under simulated atmospheric conditions to investigate the effects of the chemical composition of organic aerosol particles on their hygroscopicity and cloud condensation nucleation (CCN) activity, in order to develop quantitative relationships that could be used to more accurately incorporate aerosol-cloud interactions into regional and global atmospheric models. More specifically, the project aimed to determine the products, mechanisms, and rates of chemical reactions involved in the processing of organic aerosol particles by atmospheric oxidants and to investigate the relationships between the chemical composition of organic particles (as represented by molecule sizes and the specific functional groups that are present) and the hygroscopicity and CCN activity of oxidized POA and SOA formed from the oxidation of the major classes of anthropogenic and biogenic VOCs that are emitted to the atmosphere, as well as model hydrocarbons. The general approach for this project was

  9. On aerosol hygroscopicity, cloud condensation nuclei (CCN) spectra and critical supersaturation measured at two remote islands of Korea between 2006 and 2009

    NASA Astrophysics Data System (ADS)

    Kim, J. H.; Yum, S. S.; Shim, S.; Yoon, S.-C.; Hudson, J. G.; Park, J.; Lee, S.-J.

    2011-12-01

    Aerosol size distribution, total concentration (i.e. condensation nuclei (CN) concentration, NCN), cloud condensation nuclei (CCN) concentration (NCCN), hygroscopicity at ~90% relative humidity (RH) were measured at a background monitoring site at Gosan, Jeju Island, south of the Korean Peninsula in August 2006, April to May 2007 and August to October 2008. Similar measurements took place in August 2009 at another background site (Baengnyeongdo Comprehensive Monitoring Observatory, BCMO) on the island of Baengnyeongdo, off the west coast of the Korean Peninsula. Both islands were found to be influenced by continental sources regardless of season and year. Average values for all of the measured NCCN at 0.2, 0.6 and 1.0% supersaturations (S), NCN, and geometric mean diameter (Dg) from both islands were in the range of 1043-3051 cm-3, 2076-4360 cm-3, 2713-4694 cm-3, 3890-5117 cm-3 and 81-98 nm, respectively. Although the differences in Dg and NCN were small between Gosan and BCMO, NCCN at various S was much higher at the latter, which is closer to China. Most of the aerosols were internally mixed and no notable differences in hygroscopicity were found between the days of strong pollution influence and the non-pollution days for both islands. During the 2008 and 2009 campaigns, critical supersaturation for CCN nucleation (Sc) for selected particle sizes was measured. Particles of 100 nm diameters had mean Sc of 0.19 ± 0.02% during 2008 and those of 81 and 110 nm diameters had mean Sc of 0.26 ± 0.07% and 0.17 ± 0.04%, respectively, during 2009. The values of the hygroscopicity parameter (κ), estimated from measured Sc, were mostly higher than the κ values obtained from the measured hygroscopic growth at ~90% RH. For the 2008 campaign, NCCN at 0.2, 0.6 and 1.0% S were predicted based on measured dry particle size distributions and various ways of representing particle hygroscopicity. The best closure was obtained when temporally varying and size

  10. Hygroscopic and Chemical Properties of Aerosols collected near a Copper Smelter: Implications for Public and Environmental Health

    PubMed Central

    Sorooshian, Armin; Csavina, Janae; Shingler, Taylor; Dey, Stephen; Brechtel, Fred J.; Sáez, A. Eduardo; Betterton, Eric A.

    2012-01-01

    Particulate matter emissions near active copper smelters and mine tailings in the southwestern United States pose a potential threat to nearby environments owing to toxic species that can be inhaled and deposited in various regions of the body depending on the composition and size of the particles, which are linked by particle hygroscopic properties. This study reports the first simultaneous measurements of size-resolved chemical and hygroscopic properties of particles next to an active copper smelter and mine tailings by the towns of Hayden and Winkelman in southern Arizona. Size-resolved particulate matter samples collected near an active copper smelter were examined with inductively coupled plasma mass spectrometry, ion chromatography, and a humidified tandem differential mobility analyzer. Aerosol particles collected at the measurement site are enriched in metals and metalloids (e.g. arsenic, lead, and cadmium) and water-uptake measurements of aqueous extracts of collected samples indicate that the particle diameter range of particles most enriched with these species (0.18–0.55 µm) overlaps with the most hygroscopic mode at a relative humidity of 90% (0.10–0.32 µm). These measurements have implications for public health, microphysical effects of aerosols, and regional impacts owing to the transport and deposition of contaminated aerosol particles. PMID:22852879

  11. O the Role of Water Growth in Atmospheric Aerosol

    NASA Astrophysics Data System (ADS)

    Pitchford, Marc Lynn

    1992-01-01

    Atmospheric particle growth by condensation of water vapor was investigated using sophisticated particle growth and compositional measurements made during the Winter of 1990 at Grand Canyon National Park, AZ. Growth measurements by the Tandem Differential Mobility Analyzer (TDMA) and fine particle compositional analysis data were examined to assess the nature of the particles and the applicability of certain growth and composition models. A model was developed to estimate the sulfate to ammonium ion concentration ratio by apportioning measured hydrogen concentrations between organic and sulfate aerosol components. The model had insufficient resolution for this data to determine the ion ratio. The overall volume fraction of soluble material as determined by chemical analysis of particle samples was apportioned between high growth and low growth particles by a model based upon TDMA measured growth data. Growth data indicate the simultaneous presence of two, and occasionally three, types of particles. At relative humidities above about 78%, particles split into two distinguishable growth categories. Most of the particles grew considerably (categorized as more hygroscopic), while a small fraction of the particles grew slightly (categorized as less hygroscopic). On a few days, particles separated by growth at relative humidities in the mid-60% range, with a small fraction of the particles having high growth. At higher relative humidities these particles became indistinguishable from the more hygroscopic particles. Sulfate species dominate the soluble fraction most days, with nitrates occasionally in comparable concentrations. The model to estimate the soluble fraction of the particles in the more and less hygroscopic growth categories also determines the soluble material growth characteristic, which is assumed to be the same for all particles in any individual TDMA measurement. The predicted growth characteristics for the soluble material is in good agreement with

  12. Chemical composition, microstructure, and hygroscopic properties of aerosol particles at the Zotino Tall Tower Observatory (ZOTTO), Siberia, during a summer campaign

    SciTech Connect

    Mikhailov, E. F.; Mironov, G. N.; Pöhlker, C.; Chi, X.; Krüger, M. L.; Shiraiwa, M.; Förster, J. -D.; Pöschl, U.; Vlasenko, S. S.; Ryshkevich, T. I.; Weigand, M.; Kilcoyne, A. L. D.; Andreae, M. O.

    2015-03-16

    In this study we describe the hygroscopic properties of accumulation- and coarse-mode aerosol particles sampled at the Zotino Tall Tower Observatory (ZOTTO) in Central Siberia (61° N; 89° E) from 16 to 21 June 2013. The hygroscopic growth measurements were supplemented with chemical analyses of the samples, including inorganic ions and organic/elemental carbon. In addition, the microstructure and chemical composition of aerosol particles were analyzed by X-ray micro-spectroscopy (STXM-NEXAFS) and transmission electron microscopy (TEM). A mass closure analysis indicates that organic carbon accounted for 61 and 38% of PM in the accumulation mode and coarse mode, respectively. The water soluble fraction of organic matter was estimated to be 52 and 8% of PM in these modes. Sulfate, predominantly in the form of ammoniated sulfate, was the dominant inorganic component in both size modes: ~ 34% in the accumulation vs. ~ 47% in the coarse mode.

    The hygroscopic growth measurements were conducted with a filter-based differential hygroscopicity analyzer (FDHA) over the range of 5–99.4% RH in the hydration and dehydration operation modes. The FDHA study indicates that both accumulation and coarse modes exhibit pronounced water uptake approximately at the same RH, starting at ~ 70%, while efflorescence occurred at different humidities, i.e., at ~ 35% RH for submicron particles vs. ~ 50% RH for supermicron particles. This ~ 15% RH difference was attributed to higher content of organic material in the submicron particles, which suppresses water release in the dehydration experiments.

    The kappa mass interaction model (KIM) was applied to characterize and parameterize non-ideal solution behavior and concentration-dependent water uptake by atmospheric aerosol samples in the 5–99.4% RH range. Based on KIM, the volume-based hygroscopicity parameter, κv, was calculated. The κv, ws value related to the water soluble (ws) fraction was

  13. Size Resolved measurements of aerosol hygroscopicity and mixing state during Green Ocean Amazon (GoAmazon) 2014

    NASA Astrophysics Data System (ADS)

    Thalman, R. M.; Artaxo, P.; Campuzano Jost, P.; Barbosa, H. M.; Day, D. A.; de Sá, S. S.; Hu, W.; Jimenez, J. L.; Kuang, C.; Palm, B. B.; Krüger, M. L.; Manzi, A. O.; Martin, S. T.; Poeschl, U.; Sedlacek, A. J., III; Senum, G.; Souza, R. A. F. D.; Springston, S. R.; Alexander, M. L.; Watson, T. B.; Wang, J.

    2014-12-01

    Measurements of size-resolved cloud condensation nucleai (CCN) spectra were performed at the T3 site of the Green Ocean Amazon (GoAmazon) field project located near Manacapuru, Brazil during 2014. The T3 site is a receptor site for both polluted urban down-wind (Manaus, BR a city of several million 70 km up wind) and background (Amazon rainforest) air-masses and can provide a contrast between clean and polluted conditions. Particle hygroscopicity (kappa) and mixing state were calculated from the particle activation spectrum measured by size selecting aerosols and exposing them to a wide range of supersaturation in the CCN counter (Droplet Measurement Technologies Continuous-Flow Streamwise Thermal Gradient CCN Chamber). The supersaturation was varied between 0.07 and 1.1% by changing a combination of both total flow rate and temperature gradient in the CCN counter. Measured spectra were examined for air masses with different level of influence from Manaus plume. Particle hygroscopicity generally peaked near noon local time which was broadly consistent with the trend in aerosol sulfate. The average kappa values during the first intensive operation period were 0.14±0.05, 0.14±0.04 and 0.16±0.06 for 75, 112 and 171 nm particles respectively. Evaluation of particle hygroscopicity and dispersion (mixing state) will be presented with respect to size and level of pollution.

  14. Aging of secondary organic aerosol from small aromatic VOCs. Changes in chemical composition, mass yield, volatility and hygroscopicity

    DOE PAGESBeta

    Hildebrandt Ruiz, L.; Paciga, A. L.; Cerully, K.; Nenes, A.; Donahue, N. M.; Pandis, S. N.

    2014-12-12

    Secondary organic aerosol (SOA) is transformed after its initial formation, but this chemical aging of SOA is poorly understood. Experiments were conducted in the Carnegie Mellon environmental chamber to form and transform SOA from the photo-oxidation of toluene and other small aromatic volatile organic compounds (VOCs) in the presence of NOx. The effects of chemical aging on organic aerosol (OA) composition, mass yield, volatility and hygroscopicity were explored. Higher exposure to the hydroxyl radical resulted in different OA composition, average carbon oxidation state OSC) and mass yield. The OA oxidation state generally increased during photo-oxidation, and the final OA OSmore » C ranged from -0.29 to 0.45 in the performed experiments. The volatility of OA formed in these different experiments varied by as much as a factor of 30, demonstrating that the OA formed under different oxidizing conditions can have significantly different saturation concentration. There was no clear correlation between hygroscopicity and oxidation state for this relatively hygroscopic SOA.« less

  15. Relating hygroscopicity and optical properties to chemical composition and structure of secondary organic aerosol particles generated from the ozonolysis of α-pinene

    NASA Astrophysics Data System (ADS)

    Denjean, C.; Formenti, P.; Picquet-Varrault, B.; Pangui, E.; Zapf, P.; Katrib, Y.; Giorio, C.; Tapparo, A.; Monod, A.; Temime-Roussel, B.; Decorse, P.; Mangeney, C.; Doussin, J. F.

    2015-03-01

    Secondary organic aerosol (SOA) were generated from the ozonolysis of α-pinene in the CESAM (French acronym for Experimental Multiphasic Atmospheric Simulation Chamber) simulation chamber. The SOA formation and aging were studied by following their optical, hygroscopic and chemical properties. The optical properties were investigated by determining the particle complex refractive index (CRI). The hygroscopicity was quantified by measuring the effect of relative humidity (RH) on the particle size (size growth factor, GF) and on the scattering coefficient (scattering growth factor, f(RH)). The oxygen to carbon atomic ratios (O : C) of the particle surface and bulk were used as a sensitive parameter to correlate the changes in hygroscopic and optical properties of the SOA composition during their formation and aging in CESAM. The real CRI at 525 nm wavelength decreased from 1.43-1.60 (±0.02) to 1.32-1.38 (±0.02) during the SOA formation. The decrease in the real CRI correlated to the O : C decrease from 0.68 (±0.20) to 0.55 (±0.16). In contrast, the GF remained roughly constant over the reaction time, with values of 1.02-1.07 (±0.02) at 90% (±4.2%) RH. Simultaneous measurements of O : C of the particle surface revealed that the SOA was not composed of a homogeneous mixture, but contained less oxidised species at the surface which may limit water absorption. In addition, an apparent change in both mobility diameter and scattering coefficient with increasing RH from 0 to 30% was observed for SOA after 14 h of reaction. We postulate that this change could be due to a change in the viscosity of the SOA from a predominantly glassy state to a predominantly liquid state.

  16. Ambient Observations of Sub-1.0 Hygroscopic Growth Factor and f(RH) Values: Case Studies from Surface and Airborne Measurements

    NASA Astrophysics Data System (ADS)

    Ortega, A. M.; Shingler, T.; Crosbie, E.; Wonaschutz, A.; Froyd, K. D.; Adler, G.; Gao, R. S.; Schwarz, J. P.; Perring, A. E.; Brock, C. A.; Beyersdorf, A. J.; Ziemba, L. D.; Jimenez, J. L.; Campuzano Jost, P.; Wisthaler, A.; Sorooshian, A.

    2015-12-01

    Hygroscopic growth occurs when particles take up water vapor and grow when exposed to elevated relative humidity (RH), and is controlled largely by chemical composition. Previous laboratory studies of biomass burning and combustion particles observed particle size shrinkage as soot aerosols, especially those with coatings, were exposed to increasing RH levels, which resulted in sub-1.0 hygroscopicity parameter values (i.e., ratio of humidified-to-dry diameter g(RH) and ratio of humidified-to-dry scattering coefficients f(RH)). To investigate the potential for sub-1.0 hygroscopicity in ambient aerosol, we utilized data from (i) a ship-board HTDMA during E-PEACE 2011, (ii) multiple instruments on the DC8 during SEAC4RS-2013, as well as (iii) the DASH-SP during measurement intensives in Summer 2014 and Winter 2015 in Tucson, Arizona. Suppressed hygroscopicity, including sub-1.0 g(RH), was observed during smoke-influenced periods in SEAC4RS, episodic events in the winter season in Arizona, and smoke-influenced air during E-PEACE. Across the range of RH investigated (75-95%), sub-1.0 g(RH) was lowest at the highest RH values probed (~95%). These sub-1.0 g(RH) observations are consistent with elevated black carbon and organic aerosol concentration in both E-PEACE and SEAC4RS. Collocated measurements during SEAC4RS indicate elevated spikes in black carbon concentrations are coincident with both sub-1.0 f(RH) and g(RH) observations, as well as elevated organic aerosol- and gas-phase fire tracers such as AMS f60 and PTR-MS acetonitrile concentration. This is the first set of ambient observations of sub-1.0 hygroscopicity factors g(RH) and f(RH), with consistency across different instruments, regions, and platforms. Although particle restructuring has been demonstrated in laboratory experiments, field observations are complex as soot coating, secondary chemistry, and heterogeneous processing can occur on the same time scale as measurements. This work motivates continued

  17. The impact of marine surface organic enrichment on the measured hygroscopicity parameter of laboratory generated sea-spray aerosols

    NASA Astrophysics Data System (ADS)

    Schill, S.; Novak, G.; Zimmermann, K.; Bertram, T. H.

    2014-12-01

    The ocean serves as a major source for atmospheric aerosol particles, yet the chemicophysical properties of sea spray aerosol to date are not well characterized. Understanding the transfer of organic compounds, present in the sea surface microlayer (SSML), to sea-spray particles and their resulting impact on cloud formation is important for predicting aerosol impact on climate in remote marine environments. Here, we present a series of laboratory experiments designed to probe the fractionation of select organic molecules during wave breaking. We use a representative set of organic mimics (e.g. sterols, sugars, lipids, proteins, fatty acids) to test a recent physically based model of organic enrichment in sea-spray aerosol [Burrows et al., 2014] that is based on Langmuir absorption equilibria. Experiments were conducted in the UCSD Marine Aerosol Reference Tank (MART) permitting accurate representation of wave breaking processes in the laboratory. We report kappa values for the resulting sea-spray aerosols and compare them to a predictions made using Kappa-Köhler Theory driven by a linear combination of the pure component kappa values. Hygroscopicity determinations made using the model systems are discussed within the context of measurements of CCN activity made using natural, coastal water.

  18. Aerosol Activity and Hygroscopicity Combined with Lidar Data in the Urban Atmosphere of Athens, Greece in the Frame of the HYGRA_CD Campaign

    NASA Astrophysics Data System (ADS)

    Bougiatioti, Aikaterini; Papayannis, Alexandros; Vratolis, Stergios; Argyrouli, Athina; Mihalopoulos, Nikolaos; Tsagkaraki, Maria; Nenes, Athanasios; Eleftheriadis, Konstantinos

    2016-06-01

    Measurements of cloud condensation nuclei (CCN) concentrations between 0.2-1.0% supersaturation and aerosol size distribution were performed at an urban background site of Athens during HygrA-CD. The site is affected by local and long-range transported emissions as portrayed by the external mixing of the particles, as the larger ones appear to be more hygroscopic and more CCN-active than smaller ones. Activation fractions at all supersaturations exhibit a diurnal variability with minimum values around noon, which are considerably lower than unity. This reinforces the conclusion that the aerosol is mostly externally mixed between "fresher", less hygroscopic components with more aged, CCN active constituents.

  19. Toward Quantifying the Mass-Based Hygroscopicity of Individual Submicron Atmospheric Aerosol Particles with STXM/NEXAFS and SEM/EDX

    NASA Astrophysics Data System (ADS)

    Yancey Piens, D.; Kelly, S. T.; OBrien, R. E.; Wang, B.; Petters, M. D.; Laskin, A.; Gilles, M. K.

    2014-12-01

    The hygroscopic behavior of atmospheric aerosols influences their optical and cloud-nucleation properties, and therefore affects climate. Although changes in particle size as a function of relative humidity have often been used to quantify the hygroscopic behavior of submicron aerosol particles, it has been noted that calculations of hygroscopicity based on size contain error due to particle porosity, non-ideal volume additivity and changes in surface tension. We will present a method to quantify the hygroscopic behavior of submicron aerosol particles based on changes in mass, rather than size, as a function of relative humidity. This method results from a novel experimental approach combining scanning transmission x-ray microscopy with near-edge x-ray absorption fine spectroscopy (STXM/NEXAFS), as well as scanning electron microscopy with energy dispersive x-ray spectroscopy (SEM/EDX) on the same individual particles. First, using STXM/NEXAFS, our methods are applied to aerosol particles of known composition ‒ for instance ammonium sulfate, sodium bromide and levoglucosan ‒ and validated by theory. Then, using STXM/NEXAFS and SEM/EDX, these methods are extended to mixed atmospheric aerosol particles collected in the field at the DOE Atmospheric Radiation Measurement (ARM) Climate Research Facility at the Southern Great Planes sampling site in Oklahoma, USA. We have observed and quantified a range of hygroscopic behaviors which are correlated to the composition and morphology of individual aerosol particles. These methods will have implications for parameterizing aerosol mixing state and cloud-nucleation activity in atmospheric models.

  20. Aqueous Phase Photo-Oxidation of Succinic Acid: Changes in Hygroscopic Properties and Reaction Products

    NASA Astrophysics Data System (ADS)

    Hudson, P. K.; Ninokawa, A.; Hofstra, J.; de Lijser, P.

    2013-12-01

    Atmospheric aerosol particles have been identified as important factors in understanding climate change. The extent to which aerosols affect climate is determined, in part, by hygroscopic properties which can change as a result of atmospheric processing. Dicarboxylic acids, components of atmospheric aerosol, have a wide range of hygroscopic properties and can undergo oxidation and photolysis reactions in the atmosphere. In this study, the hygroscopic properties of succinic acid aerosol, a non-hygroscopic four carbon dicarboxylic acid, were measured with a humidified tandem differential mobility analyzer (HTDMA) and compared to reaction products resulting from the aqueous phase photo-oxidation reaction of hydrogen peroxide and succinic acid. Reaction products were determined and quantified using gas chromatography-flame ionization detection (GC-FID) and GC-mass spectrometry (GC-MS) as a function of hydrogen peroxide:succinic acid concentration ratio and photolysis time. Although reaction products include larger non-hygroscopic dicarboxylic acids (e.g. adipic acid) and smaller hygroscopic dicarboxylic acids (e.g. malonic and oxalic acids), comparison of hygroscopic growth curves to Zdanovskii-Stokes-Robinson (ZSR) predictions suggests that the hygroscopic properties of many of the product mixtures are largely independent of the hygroscopicity of the individual components. This study provides a framework for future investigations to fully understand and predict the role of chemical reactions in altering atmospheric conditions that affect climate.

  1. Study of aerosol hygroscopic events over the Cabauw experimental site for atmospheric research (CESAR) using the multi-wavelength Raman lidar Caeli

    NASA Astrophysics Data System (ADS)

    Fernández, A. J.; Apituley, A.; Veselovskii, I.; Suvorina, A.; Henzing, J.; Pujadas, M.; Artíñano, B.

    2015-11-01

    This article presents a study of aerosol optical and microphysical properties under different relative humidity (RH) but well mixed layer conditions using optical and microphysical aerosol properties from multi-wavelength (MW) Raman lidar and in-situ aerosol observations collected at the Cabauw Experimental Site for Atmospheric Research (CESAR). Two hygroscopic events are described through 3 backscatter (β) and 2 extinction (α) coefficients which in turn provide intensive parameters such as the backscatter-related Ångström exponent (åβ) and the lidar ratio (LR). Along with it, profiles of RH were inferred from Raman lidar observations and therefore, as a result of varying humidity conditions, a shift on the aerosol optical properties can be described. Thus, it is observed that as RH increases, aerosols uptake water vapour, augment their size and consequently the åβ diminishes whereas the LR increases. The enhancement factor based on the backscatter coefficient at 532 nm, which characterizes the aerosol from hygroscopic standpoint, is also estimated. Finally, microphysical properties that are necessary for aerosol radiative forcing estimates - such as volume, effective radii, refractive index and size distribution, all vertically resolved - are retrieved using the inversion with regularization. Using this method, two hygroscopic events are described in detail.

  2. Investigating hygroscopic behavior and phase separation of organic/inorganic mixed phase aerosol particles with FTIR spectroscopy

    NASA Astrophysics Data System (ADS)

    Zawadowicz, M. A.; Cziczo, D. J.

    2013-12-01

    Atmospheric aerosol particles can be composed of inorganic salts, such as ammonium sulfate and sodium chloride, and therefore exhibit hygroscopic properties. Many inorganic salts have very well-defined deliquescence and efflorescence points at which they take up and lose water, respectively. For example, the deliquescence relative humidity of pure ammonium sulfate is about 80% and its efflorescence point is about 35%. This behavior of ammonium sulfate is important to atmospheric chemistry because some reactions, such as the hydrolysis of nitrogen pentoxide, occur on aqueous but not crystalline surfaces. Deliquescence and efflorescence of simple inorganic salt particles have been investigated by a variety of methods, such as IR spectroscopy, tandem mobility analysis and electrodynamic balance. Field measurements have shown that atmospheric aerosol are not typically a single inorganic salt, instead they often contain organic as well as inorganic species. Mixed inorganic/organic aerosol particles, while abundant in the atmosphere, have not been studied as extensively. Many recent studies have focused on microscopy techniques that require deposition of the aerosol on a glass slide, possibly changing its surface properties. This project investigates the deliquescence and efflorescence points, phase separation and ability to exchange gas-phase components of mixed organic and inorganic aerosol using a flow tube coupled with FTIR spectroscopy. Ammonium sulfate aerosol mixed with organic polyols with different O:C ratios, including glycerol, 1,2,6-hexanetriol, 1,4-butanediol and 1,5-pentanediol have been investigated. This project aims to study gas-phase exchange in these aerosol systems to determine if exchange is impacted when phase separation occurs.

  3. L-Leucine as an excipient against moisture on in vitro aerosolization performances of highly hygroscopic spray-dried powders.

    PubMed

    Li, Liang; Sun, Siping; Parumasivam, Thaigarajan; Denman, John A; Gengenbach, Thomas; Tang, Patricia; Mao, Shirui; Chan, Hak-Kim

    2016-05-01

    L-Leucine (LL) has been widely used to enhance the dispersion performance of powders for inhalation. LL can also protect powders against moisture, but this effect is much less studied. The aim of this study was to investigate whether LL could prevent moisture-induced deterioration in in vitro aerosolization performances of highly hygroscopic spray-dried powders. Disodium cromoglycate (DSCG) was chosen as a model drug and different amounts of LL (2-40% w/w) were added to the formulation, with the aim to explore the relationship between powder dispersion, moisture protection and physicochemical properties of the powders. The powder formulations were prepared by spray drying of aqueous solutions containing known concentrations of DSCG and LL. The particle sizes were measured by laser diffraction. The physicochemical properties of fine particles were characterized by X-ray powder diffraction (XRD), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and dynamic vapor sorption (DVS). The surface morphology and chemistry of fine particles were analyzed by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and time-of-flight secondary ion mass spectrometry (ToF-SIMS). In vitro aerosolization performances were evaluated by a next generation impactor (NGI) after the powders were stored at 60% or 75% relative humidity (RH), and 25°C for 24h. Spray-dried (SD) DSCG powders were amorphous and absorbed 30-45% (w/w) water at 70-80% RH, resulting in deterioration in the aerosolization performance of the powders. LL did not decrease the water uptake of DSCG powders, but it could significantly reduce the effect of moisture on aerosolization performances. This is due to enrichment of crystalline LL on the surface of the composite particles. The effect was directly related to the percentage of LL coverage on the surface of particles. Formulations having 61-73% (molar percent) of LL on the particle surface (which correspond to 10-20% (w

  4. Long term measurements of optical properties and their hygroscopic enhancement

    NASA Astrophysics Data System (ADS)

    Hervo, M.; Sellegri, K.; Pichon, J. M.; Roger, J. C.; Laj, P.

    2014-11-01

    Optical properties of aerosols were measured from the GAW Puy de Dôme station (1465 m) over a seven year period (2006-2012). The impact of hygroscopicity on aerosol optical properties was calculated over a two year period (2010-2011). The analysis of the spatial and temporal variability of the optical properties showed that while no long term trend was found, a clear seasonal and diurnal variation was observed on the extensive parameters (scattering, absorption). Scattering and absorption coefficients were highest during the warm season and daytime, in concordance with the seasonality and diurnal variation of the PBL height reaching the site. Intensive parameters (single scattering albedo, asymmetry factor, refractive index) did not show such a strong diurnal variability, but still indicated different values depending on the season. Both extensive and intensive optical parameters were sensitive to the air mass origin. A strong impact of hygroscopicity on aerosol optical properties was calculated, mainly on aerosol scattering, with a dependence on the aerosol type. At 90% humidity, the scattering factor enhancement (fσsca) was more than 4.4 for oceanic aerosol that have mixed with a pollution plume. Consequently, the aerosol radiative forcing was estimated to be 2.8 times higher at RH = 90% and 1.75 times higher at ambient RH when hygroscopic growth of the aerosol was considered. The hygroscopicity enhancement factor of the scattering coefficient was parameterized as a function of humidity and air mass type.

  5. Quantifying the Relationship between Organic Aerosol Composition and Hygroscopicity/CCN Activity

    SciTech Connect

    Ziemann, Paul J.; Kreidenweis, Sonia M.; Petters, Markus D.

    2013-06-30

    The overall objective for this project was to provide the data and underlying process level understanding necessary to facilitate the dynamic treatment of organic aerosol CCN activity in future climate models. The specific objectives were as follows: (1) employ novel approaches to link organic aerosol composition and CCN activity, (2) evaluate the effects of temperature and relative humidity on organic aerosol CCN activity, and (3) develop parameterizations to link organic aerosol composition and CCN activity.

  6. Continuous Measurement of Particle Hygroscopicity as a Function of Diameter

    NASA Astrophysics Data System (ADS)

    Brock, C. A.; Anderson, B. E.; Ziemba, L. D.; Thornhill, K. L.; Moore, R.; Beyersdorf, A. J.; Winstead, E. L.; Crumeyrolle, S.; Wagner, N.; Langridge, J. M.; Richardson, M.; Lack, D. A.; Law, D. C.; Shingler, T.; Sorooshian, A.

    2012-12-01

    An ultra-high sensitivity aerosol spectrometer (UHSAS, Droplet Measurement Technologies, Boulder, CO, USA) has been substantially modified to humidify the aerosol sample stream. The size distribution of deliquesced particles at humidities as high as 95% is measured. By combining a Mie model of instrument response with measurements of dry and wet size distributions, the hygroscopic growth factor as a function of particle diameter can be estimated. By operating a second, well-calibrated dry UHSAS simultaneously with the humidified UHSAS, the size-dependent particle hygroscopicity can be determined continuously, which is particularly useful for airborne sampling where rapid time response is required. The technique has been applied to laboratory particles of inorganic salts and of polystyrene latex, and to mixed sulfate/organic particles and dense forest fire smoke measured on an aircraft during the Deep Convective Clouds and Chemistry (DC3) project. Results will be compared with measurements of aerosol extinction at different RH values and of hygroscopic growth made with a differential aerosol sizing and hygroscopicity spectrometer probe (DASH-SP). Initial evaluations of changes in hygroscopicity due to processing in convective clouds will be presented. Limitations of the technique, such as the effects of external mixtures and insoluble components, will be discussed.

  7. A case study of single hygroscopicity parameter and its link to the functional groups and phase transition for urban aerosols in Taipei City

    NASA Astrophysics Data System (ADS)

    Hung, Hui-Ming; Hsu, Chia-Hung; Lin, Wei-Ting; Chen, Yu-Quan

    2016-05-01

    The hygroscopicity, functional groups and phase transitions of urban aerosol particles in Taipei City were studied using a cloud condensation nuclei counter (CCNc) with a scanning mobility particle sizer (SMPS) and an attenuated total reflectance with infrared (ATR-IR) detection technique. With the assumption of larger particles being activated first, the derived single hygroscopicity parameter (κ) exhibited an increasing trend with particle size, i.e., from 0.022 ± 0.01 at 87 ± 10 nm to 0.13 ± 0.03 at 240 ± 20 nm. The collected size-selected particles were characterized using ATR-IR for the functional groups of alkyl, carbonyl, ammonium, sulfate and nitrate, which showed various size dependence patterns, linked to different formation mechanisms. The hygroscopic response based on the ratio (xW_solute) for sample film of absorption by the enhanced water-stretching peak to that by the selected solute showed a better consistency with pure ammonium sulfate for sub-micron size particles. Based on the derived ammonium sulfate volume fraction from IR analysis, the κ received from CCNc measurements was concluded mainly contributed by ammonium sulfate for sub-micrometer particles. The increasing trend of sodium nitrate absorbance at aerosol diameter ≥1 μm was due to a reaction of nitric acid with sea salt particles. The micrometer sized particles were apparent not only in a significantly higher xW_solute than pure sodium nitrate but also had a deliquescence RH of 69 ± 1%, similar to that of sodium nitrate-sodium chloride mixtures. Overall, the organic species in this study exhibited a low hygroscopicity with less than 0.036 of contribution for the overall κ, and the major hygroscopic material of urban aerosols consisted primarily of ammonium sulfate in the sub-micrometer particles and sodium nitrate with sea salt in the coarse particles.

  8. In-cloud processes of methacrolein under simulated conditions - Part 3: Hygroscopic and volatility properties of the formed Secondary Organic Aerosol

    NASA Astrophysics Data System (ADS)

    Michaud, V.; El Haddad, I.; Liu, Y.; Sellegri, K.; Laj, P.; Villani, P.; Picard, D.; Marchand, N.; Monod, A.

    2009-03-01

    The hygroscopic and volatility properties of SOA produced from the nebulization of solutions after aqueous phase photooxidation of methacrolein was experimentally studied in laboratory, using a Volatility-Hygroscopicity Tandem DMA (VHTDMA). The obtained SOA were 80% 100°C-volatile after 5 h of reaction and only 20% 100°C-volatile after 22 h of reaction. The Hygroscopic Growth Factor (HGF) of the SOA produced from the nebulization of solutions after aqueous-phase photooxidation of methacrolein is 1.34-1.43, which is significantly higher than the HGF of SOA formed by gas-phase phtooxidation of terpenes, usually found nearly hydrophobic. These hygroscopic properties were confirmed for SOA formed by the nebulization of the same solutions where NaCl was added. The hygroscopic properties of the cloud droplet residuals decrease with the reaction time, in parallel with the formation of more refractory compounds. This decrease was mainly attributed to the 250°C-refractive fraction (presumably representative of the highest molecular weigh compounds), evolved from moderately hygroscopic (HGF of 1.52) to less hygroscopic (HGF of 1.36). Oligomerization is suggested as a process responsible for the decrease of both volatility and hygroscopicity with time. The NaCl seeded experiments enabled us to show that 19±4 mg L-1 of SOA was produced after 9.5 h of reaction and 41±9 mg L-1 after 22 h of in-cloud reaction. Because more and more SOA is formed as the reaction time increases, our results show that the reaction products formed during the aqueous-phase OH-oxidation of methacrolein may play a major role in the properties of residual particles upon droplet's evaporation. Therefore, the specific physical properties of SOA produced during cloud processes should be taken into account for a global estimation of SOA and their atmospheric impacts.

  9. Initial steps of aerosol growth

    NASA Astrophysics Data System (ADS)

    Kulmala, M.; Laakso, L.; Lehtinen, K. E. J.; Riipinen, I.; Dal Maso, M.; Anttila, T.; Kerminen, V.-M.; Hõrrak, U.; Vana, M.; Tammet, H.

    2004-12-01

    The formation and growth of atmospheric aerosols depend on several steps, namely nucleation, initial steps of growth and subsequent - mainly condensational - growth. This work focuses on the initial steps of growth, meaning the growth right after nucleation, where the interplay of curvature effects and thermodynamics has a significant role on the growth kinetics. More specifically, we investigate how ion clusters and aerosol particles grow from 1.5 nm to 20 nm (diameter) in atmospheric conditions using experimental data obtained by air ion and aerosol spectrometers. The measurements have been performed at a boreal forest site in Finland. The observed trend that the growth rate seems to increase as a function of size can be used to investigate possible growth mechanisms. Such a growth rate is consistent with a recently suggested nano-Köhler mechanism, in which growth is activated at a certain size with respect to condensation of organic vapors. The results also imply that charge-enhanced growth associated with ion-mediated nucleation plays only a minor role in the initial steps of growth, since it would imply a clear decrease of the growth rate with size. Finally, further evidence was obtained on the earlier suggestion that atmospheric nucleation and the subsequent growth of fresh nuclei are likely to be uncoupled phenomena via different participating vapors.

  10. Initial steps of aerosol growth

    NASA Astrophysics Data System (ADS)

    Kulmala, O.; Laakso, L.; Lehtinen, K. E. J.; Riipinen, I.; Dal Maso, M.; Anttila, T.; Kerminen, V.-M.; Hõrrak, U.; Vana, M.; Tammet, H.

    2004-09-01

    The formation and growth of atmospheric aerosols depend on several steps, namely nucleation, initial steps of growth and subsequent - mainly condensational - growth. This work focuses on the initial steps of growth, meaning the growth right after nucleation, where the interplay of curvature effects and thermodynamics has a significant role on the growth kinetics. More specifically, we investigate how ion clusters and aerosol particles grow from 1.5 nm to 20 nm in atmospheric conditions using experimental data obtained by air ion and aerosol spectrometers. The measurements have been performed at a boreal forest site in Finland. The observed trend that the growth rate seems to increase as a function of size can be used to investigate possible growth mechanisms. Such a growth rate is consistent with a recently suggested nano-Köhler mechanism, in which growth is activated at a certain size with respect to condensation of organic vapors. The results also imply that charge-enhance growth associated with ion-mediated nucleation plays only a minor role in the initial steps of growth, since it would imply a clear decrease of the growth rate with size. Finally, further evidence was obtained on the earlier suggestion that atmospheric nucleation and the subsequent growth of fresh nuclei are likely to be uncoupled phenomena via different participating vapors.

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

    NASA Astrophysics Data System (ADS)

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

    2009-09-01

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

  12. Nitrogenated and aliphatic organic vapors as possible drivers for marine secondary organic aerosol growth

    NASA Astrophysics Data System (ADS)

    Dall'Osto, Manuel; Ceburnis, Darius; Monahan, Ciaran; Worsnop, Douglas R.; Bialek, Jakub; Kulmala, Markku; KurtéN, Theo; Ehn, Mikael; Wenger, John; Sodeau, John; Healy, Robert; O'Dowd, Colin

    2012-06-01

    Measurements of marine aerosol chemistry, using state-of-the-art mass spectrometry, as well as aerosol microphysics, hygroscopicity and cloud condensation nuclei (CCN) activity were undertaken during new particle growth events. The events were detected in air advecting over North East (NE) Atlantic waters during the EUCAARI Intensive Observation Period in June 2008 at Mace Head, Ireland. During these growth events, the aerosol mass spectrometers illustrated increases in accumulation mode aerosol phase nitrogenated and aliphatic compounds thought to condense from the gas phase. Since the composition changes observed in the accumulation mode occurred simultaneously to the growth of the accumulation, Aitken and nucleation modes, the growth of both the nucleation mode and the Aitken mode is attributed to the condensation of these species. Nitrogenated compounds like amines are also plausible candidates in the nucleation process, as suggested by quantum mechanic calculations. It is also plausible that amides and organic nitrites, also identified by the mass spectrometers, are possible candidate chemical compounds, suggesting that multiple types of chemical species may be contributing. Given that these open ocean aerosol formation and growth events occur in very clean polar marine air masses, we suggest that the organic compounds responsible for particle formation and growth are mainly of biogenic origin. Despite increasing the particle number concentration, the initial effect is to suppress hygroscopicity and CCN activity.

  13. Glass formation and unusual hygroscopic growth of iodic acid solution droplets with relevance for iodine mediated particle formation in the marine boundary layer

    NASA Astrophysics Data System (ADS)

    Murray, B. J.; Haddrell, A. E.; Peppe, S.; Davies, J. F.; Reid, J. P.; O'Sullivan, D.; Price, H. C.; Kumar, R.; Saunders, R. W.; Plane, J. M. C.; Umo, N. S.; Wilson, T. W.

    2012-09-01

    Iodine oxide particles are known to nucleate in the marine boundary layer where gas phase molecular iodine and organoiodine species are produced by macroalgae. These ultra-fine particles may then grow through the condensation of other materials to sizes where they may serve as cloud condensation nuclei. There has been some debate over the chemical identity of the initially nucleated particles. In laboratory simulations, hygroscopic measurements have been used to infer that they are composed of insoluble I2O4, while elemental analysis of laboratory generated particles suggests soluble I2O5 or its hydrated form iodic acid, HIO3 (I2O5·H2O). In this paper we explore the response of super-micron sized aqueous iodic acid solution droplets to varying humidity using both Raman microscopy and single particle electrodynamic traps. These measurements reveal that the propensity of an iodic acid solution droplet to crystallise is negligible on drying to ~0% relative humidity (RH). On applying mechanical pressure to these droplets they shatter in a manner consistent with an ultra-viscous liquid or a brittle glass. Water retention in amorphous material at low RH is important for understanding the hygroscopic growth of aerosol particles and uptake of other condensable material. Subsequent water uptake between 10 and 20% RH causes their viscosity to reduce sufficiently that the cracked droplets flow and merge. The persistence of iodic acid solution in an amorphous state, rather than a crystalline state, suggests they will more readily accommodate other condensable material and are therefore more likely to grow to sizes where they may serve as cloud condensation nuclei. On increasing the humidity to ~90% the mass of the droplets only increases by ~20% with a corresponding increase in radius of only 6%, which is remarkably small for a highly soluble material. We suggest that the small growth factor of aqueous iodic acid solution droplets is consistent with the small aerosol growth

  14. Vapour pressures and hygroscopicity of semi-volatile organic components in ternary organic/inorganic/water aerosol droplet trapped by aerosol optical tweezers

    NASA Astrophysics Data System (ADS)

    Cai, Chen; Zhang, Yunhong

    2016-04-01

    Knowledge of the vapour pressures of semi-volatile organic compounds is of critical importance in determining their partitioning behaviour into atmospheric aerosol. Quantifying the gas/particle partitioning of organic compounds is of great importance since at present published results of the vapour pressures of compounds of interest (typically with vapour pressures lower than 0.01 Pa) can be different by several orders of magnitude and influences on SVOCs evaporation from participation of inorganic compounds remains unclear. In this study we present a new method for the retrieval of SVOCs vapour pressures from single aerosol droplets in an aerosol optical tweezers system. Measurements of the concentration of SVOC (derived from experimentally determined RI) and radius of SVOC aqueous droplets are correlated in an expression derived from the Maxwell gas phase diffusion equation for the determination of vapour pressure. ( ) dmi-= 4π dr3Conc + dConcir3 = 4πrMiDi,gas-(p ‑ p) dt 3 dt i dt RT i,∞ i,r Relationship between r dr/dt (nm2s‑1) and r2dConcentration/dt (nm2gL‑1s‑1) is presented, in which the slope is derived for determination of hygroscopic line whilst the axis intercept can be determined to estimate vapour pressure. Briefly the method relies on the levitation of a droplet (3-7 μm radius) in an aerosol optical tweezers system. In this system the droplet acts as a microcavity and the size and refractive index of the particle can be extracted by using Mie theory to fit the positions of the "whispering gallery modes" in the cavity enhanced Raman spectroscopy fingerprint. The vapour pressure can then be extracted from the correlation between the rate of change of particle radius with the rate of change of composition (refractive index, n). We will show that information about the hygroscopicity of the particle and how this changes as the particle evaporates can also be determined from the changing slopes of these plots.

  15. The Global Ozone and Aerosol Profiles and Aerosol Hygroscopic Effect and Absorption Optical Depth (GOA2HEAD) Network Initiative

    NASA Astrophysics Data System (ADS)

    Gao, R. S.; Elkins, J. W.; Frost, G. J.; McComiskey, A. C.; Murphy, D. M.; Ogren, J. A.; Petropavlovskikh, I. V.; Rosenlof, K. H.

    2014-12-01

    Inverse modeling using measurements of ozone (O3) and aerosol is a powerful tool for deriving pollutant emissions. Because they have relatively long lifetimes, O3 and aerosol are transported over large distances. Frequent and globally spaced vertical profiles rather than ground-based measurements alone are therefore highly desired. Three requirements necessary for a successful global monitoring program are: Low equipment cost, low operation cost, and reliable measurements of known uncertainty. Conventional profiling using aircraft provides excellent data, but is cost prohibitive on a large scale. Here we describe a new platform and instruments meeting all three global monitoring requirements. The platform consists of a small balloon and an auto-homing glider. The glider is released from the balloon at about 5 km altitude, returning the light instrument package to the launch location, and allowing for consistent recovery of the payload. Atmospheric profiling can be performed either during ascent or descent (or both) depending on measurement requirements. We will present the specifications for two instrument packages currently under development. The first measures O3, RH, p, T, dry aerosol particle number and size distribution, and aerosol optical depth. The second measures dry aerosol particle number and size distribution, and aerosol absorption coefficient. Other potential instrument packages and the desired spatial/temporal resolution for the GOA2HEAD monitoring initiative will also be discussed.

  16. DOSIMETRY MODEL FOR HYGROSCOPIC SULFATE AEROSOLS IN SELECTED TEMPERATURE AND RELATIVE HUMIDITY PATTERNS

    EPA Science Inventory

    Sulfate aerosols (NH4HSO4,(NH4)2SO4 and H2SO4) are of international health effects concern because of their global prevalence and potential irritant or toxic effects on human health. To assess hazards following inhalation exposure, the total dose delivered to the human respirator...

  17. Water uptake of multicomponent organic mixtures and their influence on hygroscopicity of inorganic salts.

    PubMed

    Wang, Yuanyuan; Jing, Bo; Guo, Yucong; Li, Junling; Tong, Shengrui; Zhang, Yunhong; Ge, Maofa

    2016-07-01

    The hygroscopic behaviors of atmospherically relevant multicomponent water soluble organic compounds (WSOCs) and their effects on ammonium sulfate (AS) and sodium chloride were investigated using a hygroscopicity tandem differential mobility analyzer (HTDMA) in the relative humidity (RH) range of 5%-90%. The measured hygroscopic growth was compared with predictions from the Extended-Aerosol Inorganics Model (E-AIM) and Zdanovskii-Stokes-Robinson (ZSR) method. The equal mass multicomponent WSOCs mixture containing levoglucosan, succinic acid, phthalic acid and humic acid showed gradual water uptake without obvious phase change over the whole RH range. It was found that the organic content played an important role in the water uptake of mixed particles. When organic content was dominant in the mixture (75%), the measured hygroscopic growth was higher than predictions from the E-AIM or ZSR relation, especially under high RH conditions. For mass fractions of organics not larger than 50%, the hygroscopic growth of mixtures was in good agreement with model predictions. The influence of interactions between inorganic and organic components on the hygroscopicity of mixed particles was related to the salt type and organic content. These results could contribute to understanding of the hygroscopic behaviors of multicomponent aerosol particles. PMID:27372129

  18. A case study of single hygroscopicity parameter and its link to the functional groups and phase transition for urban aerosols in Taipei City

    NASA Astrophysics Data System (ADS)

    Hung, Hui-Ming; Hsu, Chia-Hung; Lin, Wei-Ting; Chen, Yu-Quan

    2016-05-01

    The hygroscopicity, functional groups and phase transitions of urban aerosol particles in Taipei City were studied using a cloud condensation nuclei counter (CCNc) with a scanning mobility particle sizer (SMPS) and an attenuated total reflectance with infrared (ATR-IR) detection technique. With the assumption of larger particles being activated first, the derived single hygroscopicity parameter (κ) exhibited an increasing trend with particle size, i.e., from 0.022 ± 0.01 at 87 ± 10 nm to 0.13 ± 0.03 at 240 ± 20 nm. The collected size-selected particles were characterized using ATR-IR for the functional groups of alkyl, carbonyl, ammonium, sulfate and nitrate, which showed various size dependence patterns, linked to different formation mechanisms. The hygroscopic response based on the ratio (xW_solute) for sample film of absorption by the enhanced water-stretching peak to that by the selected solute showed a better consistency with pure ammonium sulfate for sub-micron size particles. Based on the derived ammonium sulfate volume fraction from IR analysis, the κ received from CCNc measurements was concluded mainly contributed by ammonium sulfate for sub-micrometer particles. The increasing trend of sodium nitrate absorbance at aerosol diameter ≥1 μm was due to a reaction of nitric acid with sea salt particles. The micrometer sized particles were apparent not only in a significantly higher xW_solute than pure sodium nitrate but also had a deliquescence RH of 69 ± 1%, similar to that of sodium nitrate-sodium chloride mixtures. Overall, the organic species in this study exhibited a low hygroscopicity with less than 0.036 of contribution for the overall κ, and the major hygroscopic material of urban aerosols consisted primarily of ammonium sulfate in the sub-micrometer particles and sodium nitrate with sea salt in the coarse particles.

  19. Hygroscopic Properties of Oxidation Products of Terpenes

    NASA Astrophysics Data System (ADS)

    Lodhi, N. A.; Mozurkewich, M.

    2009-05-01

    To understand the hygroscopic growth factor (HGF) of secondary organic aerosol (SOA) formed by the oxidation of terpenes, a series of seeded and nucleation experiments were conducted at the York University smog chamber facility. Oxidation of terpenes by OH was carried out in a dry chamber (RH˜5%). In nucleation experiments particles formed were pure organic and their hygroscopic growth factor was measured as function of relative humidity by using a tandem differential mobility analyzer (HTDMA). Humidograms of these particles don't show any deliquescence or efflorescence. Humidograms of pure organic particles formed by the oxidation products of β-pinene show slight but smooth take up of water while particles formed by α-pinene and δ3-carene exhibit very little or no water uptake. Experimental results were fitted with an empirical equation and the hygroscopicity parameter for the particles formed by β-pinene was found to be 0.019±0.009. To examine the interaction of organic and inorganic phases, monodisperse ammonium sulfate seed particles injected into the smog chamber were allowed to undergo condensational growth due to partitioning of terpenes oxidation products from the gas phase. Humidograms of seeded particles show both smooth hygroscopic growth and deliquescence. These experimental results were fitted with a numerical model that accounts for water uptake by both phases and for the gradual dissolution of ammonium sulfate. The results show that volume additivity is a reasonable approximation for this system and that HTDMA results can be inverted to obtain the organic hygroscopicity parameter and the relative amounts of organic and inorganic material

  20. Changes of hygroscopicity and morphology during ageing of diesel soot

    NASA Astrophysics Data System (ADS)

    Tritscher, Torsten; Jurányi, Zsófia; Martin, Maria; Chirico, Roberto; Gysel, Martin; Heringa, Maarten F.; DeCarlo, Peter F.; Sierau, Berko; Prévôt, André S. H.; Weingartner, Ernest; Baltensperger, Urs

    2011-07-01

    Soot particles are an important component of atmospheric aerosol and their interaction with water is important for their climate effects. The hygroscopicity of fresh and photochemically aged soot and secondary organic aerosol (SOA) from diesel passenger car emissions was studied under atmospherically relevant conditions in a smog chamber at sub-and supersaturation of water vapor. Fresh soot particles show no significant hygroscopic growth nor cloud condensation nucleus (CCN) activity. Ageing by condensation of SOA formed by photooxidation of the volatile organic carbon (VOC) emission leads to increased water uptake and CCN activity as well as to a compaction of the initially non-spherical soot particles when exposed to high relative humidity (RH). It is important to consider the latter effect for the interpretation of mobility based measurements. The vehicle with oxidation catalyst (EURO3) emits much fewer VOCs than the vehicle without after-treatment (EURO2). Consequently, more SOA is formed for the latter, resulting in more pronounced effects on particle hygroscopicity and CCN activity. Nevertheless, the aged soot particles did not reach the hygroscopicity of pure SOA particles formed from diesel VOC emissions, which are similarly hygroscopic (0.06 < κH - TDMA < 0.12 and 0.09 < κCCN < 0.14) as SOA from other precursor gases investigated in previous studies.

  1. Properties of jet engine combustion particles during the PartEmis experiment. Hygroscopic growth at supersaturated conditions

    NASA Astrophysics Data System (ADS)

    Hitzenberger, R.; Giebl, H.; Petzold, A.; Gysel, M.; Nyeki, S.; Weingartner, E.; Baltensperger, U.; Wilson, C. W.

    2003-07-01

    During the EU Project PartEmis, the microphysical properties of aircraft combustion aerosol were investigated. This study is focused on the ability of exhaust aerosols to act as cloud condensation nuclei (CCN). The combustor was operated at two different conditions representing old and modern aircraft engine technology. CCN concentrations were measured with the University of Vienna CCN counter [ Giebl et al., 2002] at supersaturations around 0.7%. The activation ratio (fraction of CCN in total aerosol) depended on the fuel sulphur content (FSC) and also on the operation conditions. CCN/CN ratios increased from 0.93 through 1.43 to 5.15 . 10-3 (old cruise conditions) and 0.67 through 3.04 to 7.94 . 10-3 (modern cruise conditions) when FSC increased from 50 through 410 to1270 μg/g. The activation behaviour was modelled using classical theories and with a semi-empirical model [ Gysel et al., 2003] based on measured hygroscopicity of the aerosol under subsaturated conditions, which gave the best agreement.

  2. Hygroscopic properties of NaCl and NaNO3 mixture particles as reacted inorganic sea-salt aerosol surrogates

    NASA Astrophysics Data System (ADS)

    Gupta, D.; Kim, H.; Park, G.; Li, X.; Eom, H.-J.; Ro, C.-U.

    2015-03-01

    NaCl in fresh sea-salt aerosol (SSA) particles can partially or fully react with atmospheric NOx/HNO3, so internally mixed NaCl and NaNO3 aerosol particles can co-exist over a wide range of mixing ratios. Laboratory-generated, micrometer-sized NaCl and NaNO3 mixture particles at 10 mixing ratios (mole fractions of NaCl (XNaCl) = 0.1 to 0.9) were examined systematically to observe their hygroscopic behavior, derive experimental phase diagrams for deliquescence and efflorescence, and understand the efflorescence mechanism. During the humidifying process, aerosol particles with the eutonic composition (XNaCl = 0.38) showed only one phase transition at their mutual deliquescence relative humidity (MDRH) of 67.9 (±0.5)% On the other hand, particles with other mixing ratios showed two distinct deliquescence transitions; i.e., the eutonic component dissolved at MDRH, and the remainder in the solid phase dissolved completely at their DRHs depending on the mixing ratios, resulting in a phase diagram composed of four different phases, as predicted thermodynamically. During the dehydration process, NaCl-rich particles (XNaCl > 0.38) showed a two stage efflorescence transition: the first stage was purely driven by the homogeneous nucleation of NaCl and the second stage at the mutual efflorescence RH (MERH) of the eutonic components, with values in the range of 30.0-35.5%. Interestingly, aerosol particles with the eutonic composition (XNaCl = 0.38) also showed two-stage efflorescence, with NaCl crystallizing first followed by heterogeneous nucleation of the remaining NaNO3 on the NaCl seeds. NaNO3-rich particles (XNaCl ≤ 0.3) underwent single-stage efflorescence transitions at ERHs progressively lower than the MERH because of the homogeneous nucleation of NaCl and the almost simultaneous heterogeneous nucleation of NaNO3 on the NaCl seeds. SEM/EDX elemental mapping indicated that the effloresced NaCl-NaNO3 particles at all mixing ratios were composed of a homogeneously

  3. 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

  4. 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

  5. Aerosol Hygroscopicity Measured in Pristine and Polluted Conditions During the First Year of the GoAmazon 2014/15 Experiment

    NASA Astrophysics Data System (ADS)

    Barbosa, H. M.; Krüger, M. L.; Thalman, R.; Wang, J.; Pauliquevis, T.; Brito, J.; Poeschl, U.; Andreae, M. O.; Martin, S. T.; Artaxo, P.

    2015-12-01

    The effects of aerosol particles on cloud microphysical properties, cloud cover, precipitation, and regional climate are an important aspect of the climate system. The Amazon region is particularly susceptible to changes in number-diameter distributions of the atmospheric particle population because of the low background concentrations and high water vapor levels, indicating a regime of cloud properties that is highly sensitive to aerosol microphysics. This natural regime, different from most other continental areas worldwide, is expected to be perturbed by the interaction of the Manaus urban plume with the natural the natural environment. Studying the effects of this interaction on the cloud and aerosol life cycle is the main objective of the Green Ocean Amazon (GoAmazon) campaign taking place around Manaus-Brazil from January 2014 to December 2015. In this paper we compare the particle hygroscopicity calculated from measurements of size-resolved cloud condensation nuclei performed at three ground sites during the first year of the GoAmazon 2014/15 experiment. Site T3 is about 70 km downwind from Manaus experiencing urban polluted and background conditions; site T2 is just across the Rio Negro from Manaus and CCN measurements were performed there only from 15 August 2014 to 30 Jan 2015; and T0, at the Amazon Tall Tower Observatory (ATTO), is a pristine site about 200 km upwind from Manaus. Our results indicate a lower hygroscopicity under polluted conditions (mean kappa values around 0.14 to 0.16) than under clean conditions (mean kappa around 0.2 to 0.3). At the clean site, it was possible to identify peaks of large sea salt particles with organic coating, while small particles seems to be purely organic. The activation fraction and hygroscopicity will be compared and discussed as a function of particle size. The mean kappa at ATTO is 0.17+-0.05 (mean of June and September) when there is no impact from long range transport from Africa or fresh soot emissions

  6. Hygroscopic behavior of atmospherically relevant water-soluble carboxylic salts and their influence on the water uptake of ammonium sulfate

    NASA Astrophysics Data System (ADS)

    Wu, Z. J.; Nowak, A.; Poulain, L.; Herrmann, H.; Wiedensohler, A.

    2011-12-01

    The hygroscopic behavior of atmospherically relevant water-soluble carboxylic salts and their effects on ammonium sulfate were investigated using a hygroscopicity tandem differential mobility analyzer (H-TDMA). No hygroscopic growth is observed for disodium oxalate, while ammonium oxalate shows slight growth (growth factor = 1.05 at 90%). The growth factors at 90% RH for sodium acetate, disodium malonate, disodium succinate, disodium tartrate, diammonium tartrate, sodium pyruvate, disodium maleate, and humic acid sodium salt are 1.79, 1.78, 1.69, 1.54, 1.29, 1.70, 1.78, and 1.19, respectively. The hygroscopic growth of mixtures of organic salts with ammonium sulfate, which are prepared as surrogates of atmospheric aerosols, was determined. A clear shift in deliquescence relative humidity to lower RH with increasing organic mass fraction was observed for these mixtures. Above 80% RH, the contribution to water uptake by the organic salts was close to that of ammonium sulfate for the majority of investigated compounds. The observed hygroscopic growth of the mixed particles at RH above the deliquescence relative humidity of ammonium sulfate agreed well with that predicted using the Zdanovskii-Stokes-Robinson (ZSR) mixing rule. Mixtures of ammonium sulfate with organic salts are more hygroscopic than mixtures with organic acids, indicating that neutralization by gas-phase ammonia and/or association with cations of dicarbonxylic acids may enhance the hygroscopicity of the atmospheric particles.

  7. Aerosol growth in Titan's ionosphere.

    PubMed

    Lavvas, Panayotis; Yelle, Roger V; Koskinen, Tommi; Bazin, Axel; Vuitton, Véronique; Vigren, Erik; Galand, Marina; Wellbrock, Anne; Coates, Andrew J; Wahlund, Jan-Erik; Crary, Frank J; Snowden, Darci

    2013-02-19

    Photochemically produced aerosols are common among the atmospheres of our solar system and beyond. Observations and models have shown that photochemical aerosols have direct consequences on atmospheric properties as well as important astrobiological ramifications, but the mechanisms involved in their formation remain unclear. Here we show that the formation of aerosols in Titan's upper atmosphere is directly related to ion processes, and we provide a complete interpretation of observed mass spectra by the Cassini instruments from small to large masses. Because all planetary atmospheres possess ionospheres, we anticipate that the mechanisms identified here will be efficient in other environments as well, modulated by the chemical complexity of each atmosphere. PMID:23382231

  8. Glass formation and unusual hygroscopic growth of iodic acid solution droplets with relevance for iodine oxide particles in the coastal marine boundary layer

    NASA Astrophysics Data System (ADS)

    Murray, B. J.; Haddrell, A. E.; Peppe, S.; Davies, J. F.; Reid, J. P.; O'Sullivan, D.; Price, H. C.; Kumar, R.; Saunders, R. W.; Plane, J. M. C.; Umo, N. S.; Wilson, T. W.

    2012-03-01

    Iodine oxide particles are known to nucleate in the marine boundary layer where gas phase molecular iodine and organoiodine species are produced by macroalgae. There has been some debate over the chemical identity of these particles. Hygroscopic measurements have been used to infer that they are composed of insoluble I2O4, while elemental analysis of laboratory generated particles suggests soluble I2O5 or its hydrated form iodic acid, HIO3 (I2O5 · H2O). In this paper we explore the response of super-micron sized aqueous iodic acid solution droplets to varying humidity using both Raman microscopy and single particle electrodynamic traps. These measurements reveal that the propensity of an iodic acid solution droplet to crystallise is negligible on drying to ~0% relative humidity (RH). On applying mechanical pressure to these droplets they shatter in a manner consistent with an ultra-viscous liquid or a brittle glass, but subsequent water uptake between 10 and 20% RH causes their viscosity to reduce sufficiently that the cracked droplets flow and merge. The persistence of iodic acid solution in an amorphous state, rather than a crystalline state, suggests they will more readily accommodate other condensable material and are therefore more likely to grow to sizes where they may serve as cloud condensation nuclei. On increasing the humidity to ~90% the mass of the droplets only increases by ~20% with a corresponding increase in radius of only ~6 %, which is remarkably small for a highly soluble material. We suggest that the small growth factor of aqueous iodic acid solution droplets is consistent with the small aerosol growth factors observed in field experiments.

  9. 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.

  10. Aerosol hygroscopicity and its impact on atmospheric visibility and radiative forcing in Guangzhou during the 2006 PRIDE-PRD campaign

    NASA Astrophysics Data System (ADS)

    Liu, Xingang; Zhang, Yuanhang; Cheng, Yafang; Hu, Min; Han, Tingting

    2012-12-01

    The objective of this study is to quantify the relation of aerosol chemical compositions and optical properties, and to assess the impact of relative humidity (RH) on atmospheric visibility and aerosol direct radiative forcing (ADRF). Mass concentration and size distribution of aerosol chemical compositions as well as aerosol optical properties were concurrently measured at Guangzhou urban site during the PRD (Pearl River Delta) campaign from 1 to 31 July, 2006. Gaseous pollutant NO2 and meteorological parameter were simultaneously monitored. Compared with its dry condition, atmospheric ambient extinction coefficient σext(RH) averagely increased about 51% and atmospheric visibility deceased about 35%, among which RH played an important role on the optical properties of water soluble inorganic salts. (NH4)2SO4 is the most important component responsible for visibility degradation at Guangzhou. In addition, the asymmetry factor g increased from 0.64 to 0.74 with the up-scatter fraction β decreasing from 0.24 to 0.19 when RH increasing from 40% to 90%. At 80% RH, the ADRF increased about 280% compared to that at dry condition and it averagely increased about 100% during the campaign under ambient conditions. It can be inferred that aerosol water content is a key factor and could not be ignored in assessing the role of aerosols in visibility impairment and radiative forcing, especially in the regions with high RH.

  11. Hygroscopic properties and cloud condensation nuclei activation of limonene-derived organosulfates and their mixtures with ammonium sulfate

    NASA Astrophysics Data System (ADS)

    Hansen, A. M. K.; Hong, J.; Kristensen, K.; Ylisirniö, A.; Virtanen, A.; Petäjä, T.; Glasius, M.; Prisle, N. L.

    2014-12-01

    Atmospheric aerosols have the ability to act as cloud condensation nuclei (CCN), initiating the formation of clouds and hereby influencing the climate system. The ability of aerosols to act as CCN is believed to depend on particle size and chemical composition. Organosulfates (OS), e.g sulfate esters, have been observed as constituents of secondary organic aerosols in numerous atmospheric environments, even as far as the Arctic, where OS have been found to comprise 7-15% of total organic matter and 9-11% of submicron organic matter in two independent studies. However, the properties of particulate OS have not yet been investigated. Here limonene derived OS were synthesized and the hygroscopic properties of these OS and their mixtures with ammonium sulfate (AS) were examined through a series of laboratory experiments. Laboratory generated particles of limonene-derived OS and AS were analysed using a unique set-up splitting the particle flow between a Hygroscopicity Tandem Differential Mobility Analyzer and a Cloud Condensation Nuclei counter, enabling simultaneous measurements of hygroscopic growth and CCN activation. Limonene-derived OS were chosen as study components, since monoterpenes (including limonene) have been identified as important precursors of OS in field samples as well as in smog chamber experiments. AS was used as a representative of the inorganic fraction in atmospheric aerosols. The preliminary results show that limonene-derived OS exhibit weak hygroscopic growth as well as CCN activation potential, however, not as strong as AS. For the organic-inorganic mixtures, it was observed that AS dominated the hygroscopic properties over the limonene-derived OS and became dictating for the measured values of hygroscopic growth and CCN activation, when the mass fraction of AS reached 20% or above. The results will be discussed further and supplementary measurements of OS surface tension and water activity will be presented.

  12. Aerosolization characteristics of dry powder inhaler formulations for the excipient enhanced growth (EEG) application: effect of spray drying process conditions on aerosol performance.

    PubMed

    Son, Yoen-Ju; Worth Longest, P; Hindle, Michael

    2013-02-25

    The aim of this study was to develop a spray dried submicrometer powder formulation suitable for the excipient enhanced growth (EEG) application. Combination particles were prepared using the Buchi Nano spray dryer B-90. A number of spray drying and formulation variables were investigated with the aims of producing dry powder formulations that were readily dispersed upon aerosolization and maximizing the fraction of submicrometer particles. Albuterol sulfate, mannitol, L-leucine, and poloxamer 188 were selected as a model drug, hygroscopic excipient, dispersibility enhancer and surfactant, respectively. Formulations were assessed by scanning electron microscopy and aerosol performance following aerosolization using an Aerolizer dry powder inhaler (DPI). In vitro drug deposition was studied using a realistic mouth-throat (MT) model. Based on the in vitro aerosolization results, the best performing submicrometer powder formulation consisted of albuterol sulfate, mannitol, L-leucine and poloxamer 188 in a ratio of 30:48:20:2, containing 0.5% solids in a water:ethanol (80:20%, v/v) solution which was spray dried at 70 °C. The submicrometer particle fraction (FPF(1 μm/ED)) of this final formulation was 28.3% with more than 80% of the capsule contents being emitted during aerosolization. This formulation also showed 4.1% MT deposition. The developed combination formulation delivered a powder aerosol developed for the EEG application with high dispersion efficiency and low MT deposition from a convenient DPI device platform. PMID:23313343

  13. Aerosolization Characteristics of Dry Powder Inhaler Formulations for the Excipient Enhanced Growth (EEG) Application: Effect of Spray Drying Process Conditions on Aerosol Performance

    PubMed Central

    Son, Yoen-Ju; Longest, P. Worth; Hindle, Michael

    2013-01-01

    The aim of this study was to develop a spray dried submicrometer powder formulation suitable for the excipient enhanced growth (EEG) application. Combination particles were prepared using the Buchi Nano spray dryer B-90. A number of spray drying and formulation variables were investigated with the aims of producing dry powder formulations that were readily dispersed upon aerosolization and maximizing the fraction of submicrometer particles. Albuterol sulfate, mannitol, L-leucine, and poloxamer 188 were selected as a model drug, hygroscopic excipient, dispersibility enhancer and surfactant, respectively. Formulations were assessed by scanning electron microscopy and aerosol performance following aerosolization using an Aerolizer® dry powder inhaler (DPI). In vitro drug deposition was studied using a realistic mouth-throat (MT) model. Based on the in vitro aerosolization results, the best performing submicrometer powder formulation consisted of albuterol sulfate, mannitol, L-leucine and poloxamer 188 in a ratio of 30:48:20:2, containing 0.5% solids in a water:ethanol (80:20% v/v) solution which was spray dried at 70 °C. The submicrometer particle fraction (FPF1μm/ED) of this final formulation was 28.3% with more than 80% of the capsule contents being emitted during aerosolization. This formulation also showed 4.1% MT deposition. The developed combination formulation delivered a powder aerosol developed for the EEG application with high dispersion efficiency and low MT deposition from a convenient DPI device platform. PMID:23313343

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

    NASA Astrophysics Data System (ADS)

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

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

  15. Evaluation and Modification of Commercial Dry Powder Inhalers for the Aerosolization of a Submicrometer Excipient Enhanced Growth (EEG) Formulation

    PubMed Central

    Son, Yoen-Ju; Longest, P. Worth; Tian, Geng; Hindle, Michael

    2013-01-01

    The aim of this study was to evaluate and modify commercial dry powder inhalers (DPIs) for the aerosolization of a submicrometer excipient enhanced growth (EEG) formulation. The optimized device and formulation combination was then tested in a realistic in vitro mouth-throat - tracheobronchial (MT-TB) model. An optimized EEG submicrometer powder formulation, consisting of albuterol sulfate (drug), mannitol (hygroscopic excipient), L-leucine (dispersion enhancer) and poloxamer 188 (surfactant) in a ratio of 30:48:20:2 was prepared using a Büchi Nano spray dryer. The aerosolization performance of the EEG formulation was evaluated with 5 conventional DPIs: Aerolizer, Novolizer, HandiHaler, Exubera and Spiros. To improve powder dispersion, the HandiHaler was modified with novel mouth piece (MP) designs. The aerosol performance of each device was assessed using a next generation impactor (NGI) at airflow rates generating a pressure drop of 4 kPa across the DPI. In silico and in vitro deposition and hygroscopic growth of formulations was studied using a MT-TB airway geometry model. Both Handihaler and Aerolizer produced high emitted doses (ED) together with a significant submicrometer aerosol fraction. A modified HandiHaler with a MP including a three-dimensional (3D) array of rods (HH-3D) produced a submicrometer particle fraction of 38.8% with a conventional fine particle fraction (% <5µm) of 97.3%. The mass median diameter (MMD) of the aerosol was reduced below 1 µm using this HH-3D DPI. The aerosol generated from the modified HandiHaler increased to micrometer size (2.8 µm) suitable for pulmonary deposition, when exposed to simulated respiratory conditions, with negligible mouth-throat (MT) deposition (2.6 %). PMID:23608613

  16. Beyond the Alphabet Soup: Molecular Properties of Aerosol Components Influence Optics. (Invited)

    NASA Astrophysics Data System (ADS)

    Thompson, J. E.

    2013-12-01

    Components within atmospheric aerosols exhibit almost every imaginable model of chemical bonding and physical diversity. The materials run the spectrum from crystalline to amorphous, covalent to ionic, and have varying viscosities, phase, and hygroscopicity. This seminar will focus on the molecular properties of materials that influence the optical behavior of aerosols. Special focus will be placed on the polarizability of materials, hygroscopic growth, and particle phase.

  17. How Does a Raindrop Grow?: Precipitation in natural clouds may develop from ice crystals or from large hygroscopic aerosols.

    PubMed

    Braham, R R

    1959-01-16

    On the basis of presently available data, combined with present-day knowledge of the physics and chemistry of cloud particle development, it is possible to make the following generalizations about the mode of precipitation in natural clouds. 1) The all-water mechanism begins to operate as soon as a parcel of cloud air is formed and continues to operate throughout the life of the cloud. The ice-crystal mechanism, on the other hand, can begin to operate only after the top of the cloud has reached levels where ice nuclei can be effective (about -15 degrees C). Some clouds never reach this height; any precipitation from them must be through the all-water mechanism. In cold climates and at high levels in the atmosphere, the cloud bases may be very close to this critical temperature. In the tropics, approximately 25,000 feet separate the bases of low clouds from the natural ice level. 2) The number of large hygroscopic nuclei in maritime air over tropical oceans is entirely adequate to rain-out any cloud with a base below about 10,000 feet, provided the cloud duration and cloud depth is sufficient for the precipitation process to operate. Extensive trajectories over land will decrease the number of sea-salt particles, both because of sedimentation and removal in rain. Measurements show an order-of-magnitude decrease in the number of large particles as maritime air moves from the Gulf of Mexico to the vicinity of St. Louis, during the summer months. Measurements in Arizona and New Mexico show even smaller chloride concentrations, presumably because of the long overland trajectories required in reaching these areas. The maritime particles lost in overland trajectories apparently are more than replaced by particles of land origin. The latter are usually of mixed composition and are less favorable for the formation of outsized solution droplets. 3) Ice nuclei, required for the formation of ice crystals and for droplet freezing, are rather rare at temperatures higher than

  18. NOVEL MEASUREMENTS OF VOLATILITY- AND POLARITY-SEPARATED ORGANIC AEROSOL COMPOSITION AND ASSOCIATED HYGROSCOPICITY TO INVESTIGATE THE INFLUENCE OF MIXED ANTHROPOGENIC-BIOGENIC EMISSIONS ON ATMOSPHERIC AGING PROCESSES

    EPA Science Inventory

    Through the proposed study, novel measurements of compositional and hygroscopic changes during SOA formation and transformation under various mixtures of biogenic- anthropogenic sources will be obser\\led: 1) under unperturbed conditions, allowing meteorology to deliver vari...

  19. Uncertainties of simulated aerosol optical properties induced by assumptions on aerosol physical and chemical properties: an AQMEII-2 perspective

    EPA Science Inventory

    The calculation of aerosol optical properties from aerosol mass is a process subject to uncertainty related to necessary assumptions on the treatment of the chemical species mixing state, density, refractive index, and hygroscopic growth. In the framework of the AQMEII-2 model in...

  20. The Importance of Water Uptake by Aerosols in the Climate Change Problem

    NASA Astrophysics Data System (ADS)

    Ramaswamy, V.; Ginoux, P.; Randles, C.; Schwarzkopf, M. D.

    2007-12-01

    It is well understood that aerosol species have and are continuing to play a central role in the radiative forcing of the climate system. While the role of single-scattering properties of aerosols on climate is generally well- recognized, a key factor that governs the aerosol optical property viz., the hygroscopic growth has received insufficient attention particularly in terms of its role in the climatic impacts due to aerosols. A sensitivity investigation is performed that quantitatively highlights the consequence of the growth of sea-salt-organic carbon mixtures for radiative forcing. Next, we employ the GFDL coupled atmosphere-ocean model to study specifically the aerosol radiative forcing and climate response arising due to the hygroscopic features of sulfate aerosols as they have increased from preindustrial to present-day. We make use of observations of optical depth and surface concentrations to evaluate the reliability of the simulated hygroscopic growth. Regional climate responses in Europe, Asia and Africa are examined, with a focus on temperature, hydrological cycle and surface energy budgets. The importance of hygroscopicity in the climate change problem is put in perspective by comparing the climatic effects with those due to aerosol absorption as well as with those caused by the infrared-absorbing long- lived greenhouse gases. Further, we explore the climate consequence arising from the scenarios of the future emissions of aerosols and the associated hygroscopicity effects.

  1. Targeting Aerosol Deposition to and Within the Lung Airways Using Excipient Enhanced Growth

    PubMed Central

    Tian, Geng; Li, Xiang; Hindle, Michael

    2013-01-01

    Abstract Background Previous studies have characterized the size increase of combination submicrometer particles composed of a drug and hygroscopic excipient when exposed to typical airway thermodynamic conditions. The objective of this study was to determine the deposition and size increase characteristics of excipient enhanced growth (EEG) aerosols throughout the tracheobronchial (TB) airways and to evaluate the potential for targeted delivery. Methods Submicrometer particles composed of a poorly water-soluble drug (insulin) and hygroscopic excipient (sodium chloride) were considered at drug:excipient mass ratios of 50:50 and 25:75. A previously validated computational fluid dynamics model was used to predict aerosol size increase and deposition in characteristic geometries of the mouth–throat (MT), upper TB airways through the third bifurcation (B3), and remaining TB airways through B15. Additional validation experiments were also performed for albuterol sulfate:mannitol particles. Both growth of combination particles and deposition are reported throughout the conducting airways for characteristic slow and deep (SD) and quick and deep (QD) inhalations. Results For all EEG cases considered, MT deposition was less than 1% of the drug dose, which is at least one order of magnitude lower than with state-of-the-art and conventional inhalers. Final aerosol sizes exiting the TB region and entering the alveolar airways were all greater than 3 μm. For SD inhalation, deposition fractions of 20% were achieved in the lower TB region of B8–B15, which is a factor of 20–30×higher than conventional delivery devices. With QD inhalation, maximum alveolar delivery of 90% was observed. Conclusions Increasing the dose delivered to the lower TB region by a factor of 20–30×or achieving 90% delivery to the alveolar airways was considered effective aerosol targeting compared with conventional devices. The trend of higher flow rates resulting in better alveolar delivery of

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

    NASA Astrophysics Data System (ADS)

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

    2010-04-01

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

  3. Particle hygroscopicity and its link to chemical composition in the urban atmosphere of Beijing, China, during summertime

    NASA Astrophysics Data System (ADS)

    Wu, Z. J.; Zheng, J.; Shang, D. J.; Du, Z. F.; Wu, Y. S.; Zeng, L. M.; Wiedensohler, A.; Hu, M.

    2016-02-01

    Simultaneous measurements of particle number size distribution, particle hygroscopic properties, and size-resolved chemical composition were made during the summer of 2014 in Beijing, China. During the measurement period, the mean hygroscopicity parameters (κs) of 50, 100, 150, 200, and 250 nm particles were respectively 0.16 ± 0.07, 0.19 ± 0.06, 0.22 ± 0.06, 0.26 ± 0.07, and 0.28 ± 0.10, showing an increasing trend with increasing particle size. Such size dependency of particle hygroscopicity was similar to that of the inorganic mass fraction in PM1. The hydrophilic mode (hygroscopic growth factor, HGF > 1.2) was more prominent in growth factor probability density distributions and its dominance of hydrophilic mode became more pronounced with increasing particle size. When PM2.5 mass concentration was greater than 50 μg m-3, the fractions of the hydrophilic mode for 150, 250, and 350 nm particles increased towards 1 as PM2.5 mass concentration increased. This indicates that aged particles dominated during severe pollution periods in the atmosphere of Beijing. Particle hygroscopic growth can be well predicted using high-time-resolution size-resolved chemical composition derived from aerosol mass spectrometer (AMS) measurements using the Zdanovskii-Stokes-Robinson (ZSR) mixing rule. The organic hygroscopicity parameter (κorg) showed a positive correlation with the oxygen to carbon ratio. During the new particle formation event associated with strongly active photochemistry, the hygroscopic growth factor or κ of newly formed particles is greater than for particles with the same sizes not during new particle formation (NPF) periods. A quick transformation from external mixture to internal mixture for pre-existing particles (for example, 250 nm particles) was observed. Such transformations may modify the state of the mixture of pre-existing particles and thus modify properties such as the light absorption coefficient and cloud condensation nuclei activation.

  4. Hygroscopic properties of ultrafine particles at an urban site in northern Japan during the summer of 2011

    NASA Astrophysics Data System (ADS)

    Jung, Jinsang; Kawamura, Kimitaka

    2013-04-01

    To investigate the hygroscopic property of ultrafine particles, hygroscopic growth factors [g(RH)] of size-segregated atmospheric particles were measured at an urban site in Sapporo, northern Japan, during the summer of 2011. Hygroscopic growth factors at 85% RH [g(85%)] of freshly formed nucleation mode particles ranged from 1.11 to 1.28 with an average of 1.16 ± 0.06. These values are similar to those of secondary organic aerosols, suggesting that low volatile organic vapors are important to the growth of nucleated clusters into quasi-stable aerosol particles larger than 3 nm. Higher g(85%) values (range: 1.21-1.31, AVG: 1.27 ± 0.04) were obtained for grown Aitken mode nucleated particles. This result may indicate that the growth of freshly formed nucleation mode particles to the Aitken mode particles at the urban site can be attributed to condensation not only of low volatility organic vapors but also of highly water-soluble inorganic compounds like sulfuric acid. Diel variations in the number concentrations of less-hygroscopic particles [g(85%) <1.05] were similar to those in NO concentrations, suggesting that less-hygroscopic particles are mainly produced by local anthropogenic emissions such as traffic. Higher g(85%) values (1.27 ± 0.05) were obtained at a dry particle diameter of 120 nm when the air masses originated from downwind areas of the Asian continent, whereas lower g(85%) values (1.19 ± 0.06) were obtained when clean marine air masses arrived in the urban site. These results indicate that the hygroscopic property of large Aitken and small accumulation mode particles (80-165 nm) are highly influenced by the long-range transport of atmospheric particles.

  5. Biomass-burning impact on CCN number, hygroscopicity and cloud formation during summertime in the eastern Mediterranean

    NASA Astrophysics Data System (ADS)

    Bougiatioti, Aikaterini; Bezantakos, Spiros; Stavroulas, Iasonas; Kalivitis, Nikos; Kokkalis, Panagiotis; Biskos, George; Mihalopoulos, Nikolaos; Papayannis, Alexandros; Nenes, Athanasios

    2016-06-01

    This study investigates the concentration, cloud condensation nuclei (CCN) activity and hygroscopic properties of particles influenced by biomass burning in the eastern Mediterranean and their impacts on cloud droplet formation. Air masses sampled were subject to a range of atmospheric processing (several hours up to 3 days). Values of the hygroscopicity parameter, κ, were derived from CCN measurements and a Hygroscopic Tandem Differential Mobility Analyzer (HTDMA). An Aerosol Chemical Speciation Monitor (ACSM) was also used to determine the chemical composition and mass concentration of non-refractory components of the submicron aerosol fraction. During fire events, the increased organic content (and lower inorganic fraction) of the aerosol decreases the values of κ, for all particle sizes. Particle sizes smaller than 80 nm exhibited considerable chemical dispersion (where hygroscopicity varied up to 100 % for particles of same size); larger particles, however, exhibited considerably less dispersion owing to the effects of condensational growth and cloud processing. ACSM measurements indicate that the bulk composition reflects the hygroscopicity and chemical nature of the largest particles (having a diameter of ˜ 100 nm at dry conditions) sampled. Based on positive matrix factorization (PMF) analysis of the organic ACSM spectra, CCN concentrations follow a similar trend as the biomass-burning organic aerosol (BBOA) component, with the former being enhanced between 65 and 150 % (for supersaturations ranging between 0.2 and 0.7 %) with the arrival of the smoke plumes. Using multilinear regression of the PMF factors (BBOA, OOA-BB and OOA) and the observed hygroscopicity parameter, the inferred hygroscopicity of the oxygenated organic aerosol components is determined. We find that the transformation of freshly emitted biomass burning (BBOA) to more oxidized organic aerosol (OOA-BB) can result in a 2-fold increase of the inferred organic hygroscopicity; about 10

  6. 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

  7. Water uptake of clay and desert dust aerosol particles at sub- and supersaturated water vapor conditions.

    PubMed

    Herich, Hanna; Tritscher, Torsten; Wiacek, Aldona; Gysel, Martin; Weingartner, Ernest; Lohmann, Ulrike; Baltensperger, Urs; Cziczo, Daniel J

    2009-09-28

    Airborne mineral dust particles serve as cloud condensation nuclei (CCN), thereby influencing the formation and properties of warm clouds. It is therefore of atmospheric interest how dust aerosols with different mineralogy behave when exposed to high relative humidity (RH) or supersaturation (SS) with respect to liquid water. In this study the subsaturated hygroscopic growth and the supersaturated cloud condensation nucleus activity of pure clays and real desert dust aerosols were determined using a hygroscopicity tandem differential mobility analyzer (HTDMA) and a cloud condensation nuclei counter (CCNC), respectively. Five different illite, montmorillonite and kaolinite clay samples as well as three desert dust samples (Saharan dust (SD), Chinese dust (CD) and Arizona test dust (ATD)) were investigated. Aerosols were generated both with a wet and a dry disperser. The water uptake was parameterized via the hygroscopicity parameter kappa. The hygroscopicity of dry generated dust aerosols was found to be negligible when compared to processed atmospheric aerosols, with CCNC derived kappa values between 0.00 and 0.02 (the latter corresponds to a particle consisting of 96.7% by volume insoluble material and approximately 3.3% ammonium sulfate). Pure clay aerosols were generally found to be less hygroscopic than natural desert dust particles. The illite and montmorillonite samples had kappa approximately 0.003. The kaolinite samples were less hygroscopic and had kappa=0.001. SD (kappa=0.023) was found to be the most hygroscopic dry-generated desert dust followed by CD (kappa=0.007) and ATD (kappa=0.003). Wet-generated dust showed an increased water uptake when compared to dry-generated samples. This is considered to be an artifact introduced by redistribution of soluble material between the particles. Thus, the generation method is critically important when presenting such data. These results indicate any atmospheric processing of a fresh mineral dust particle which

  8. Hygroscopic behavior of atmospherically relevant water-soluble carboxylic salts and their influence on the water uptake of ammonium sulfate

    NASA Astrophysics Data System (ADS)

    Wu, Z. J.; Nowak, A.; Poulain, L.; Herrmann, H.; Wiedensohler, A.

    2011-03-01

    The hygroscopic behavior of atmospherically relevant water-soluble carboxylic salts and their effects on ammonium sulfate was investigated using a hygroscopicity tandem differential mobility analyzer (H-TDMA). No hygroscopic growth is observed for sodium oxalate, while ammonium oxalate shows slight growth (growth factor = 1.05 at 90%). The growth factors at 90% RH for sodium acetate, sodium malonate, sodium succinate, sodium tartrate, ammonium tartrate, sodium pyruvate, sodium maleate, and humic acid sodium salt are 1.79, 1.78, 1.69, 1.54, 1.29, 1.70, 1.78, and 1.19, respectively. The mixtures of organic salts with ammonium sulfate, which are prepared simulating the atmospheric aerosols, are determined. A clear shift in DRH of mixture to lower RH is observed with increasing organic mass fraction. Above RH = 80%, the humidograms of the different mixtures are quite close to that of pure ammonium sulfate. Köhler theory is used to predict the effective hygroscopicity parameter, κ, for mixtures at 90% RH. The results show that Köhler theory underestimated kappa for mixtures without considering the water solubility of ammonium oxalate. However, if the water solubility of ammonium oxalate is taken into account, the results show a much better agreement with those derived from H-TDMA measurements.

  9. Experimental and theoretical investigation of nucleation and growth of atmospheric aerosols

    NASA Astrophysics Data System (ADS)

    Zhao, Jun

    Aerosol particles have profound impacts on human health, atmospheric radiation, and cloud microphysics and these impacts are strongly dependent on particle sizes. However, formation and growth of atmospheric particles are currently not well understood. In this work, laboratory and theoretical studies have been performed to investigate the formation and growth of atmospheric particles. The first two parts of the dissertation are a laboratory investigation of new particle formation and growth, and a theoretical study of atmospheric molecular complexes and clusters. The nucleation rate was considerably enhanced in the presence of cis-pinonic acid and ammonia. The composition of the critical cluster was estimated from the dependence of the nucleation rate on the precursor concentration and the time evolution of the clusters was then simulated using molecular dynamic simulations. Results from quantum chemical calculations and quantum theory of atoms in molecules (QTAIM) reveal that formation of strong hydrogen bonding between an organic acid and sulfuric acid is likely responsible for a reduction of the nucleation barrier by modifying the hydrophobic properties of the organic acid and allowing further addition of hydrophilic species (e.g., H2SO4, H2O, and possibly NH 3) to the hydrophilic side of the clusters. This promotes growth of the nascent cluster to overcome the nucleation barrier and thus enhances the nucleation in the atmosphere. The last part of this dissertation is the laboratory investigation of heterogeneous interactions of atmospheric carbonyls with sulfuric acid. Direct measurement has been performed to investigate the heterogeneous uptake of atmospheric carbonyls on sulfuric acid. Important parameters have been obtained from the time-dependent or time-independent uptake profiles. The results indicated that the acid-catalyzed reactions of larger aldehydes (e.g. octanal and 2, 4-hexadienal) in sulfuric acid solution were attributed to aldol condensation in

  10. Aerosol growth in Titan’s ionosphere

    PubMed Central

    Lavvas, Panayotis; Yelle, Roger V.; Koskinen, Tommi; Bazin, Axel; Vuitton, Véronique; Vigren, Erik; Galand, Marina; Wellbrock, Anne; Coates, Andrew J.; Wahlund, Jan-Erik; Crary, Frank J.; Snowden, Darci

    2013-01-01

    Photochemically produced aerosols are common among the atmospheres of our solar system and beyond. Observations and models have shown that photochemical aerosols have direct consequences on atmospheric properties as well as important astrobiological ramifications, but the mechanisms involved in their formation remain unclear. Here we show that the formation of aerosols in Titan’s upper atmosphere is directly related to ion processes, and we provide a complete interpretation of observed mass spectra by the Cassini instruments from small to large masses. Because all planetary atmospheres possess ionospheres, we anticipate that the mechanisms identified here will be efficient in other environments as well, modulated by the chemical complexity of each atmosphere. PMID:23382231

  11. Cloud Forming Potential of Aminium Carboxylate Aerosols

    NASA Astrophysics Data System (ADS)

    Gomez Hernandez, M. E.; McKeown, M.; Taylor, N.; Collins, D. R.; Lavi, A.; Rudich, Y.; Zhang, R.

    2014-12-01

    Atmospheric aerosols affect visibility, air quality, human health, climate, and in particular the aerosol direct and indirect forcings represent the largest uncertainty in climate projections. In this paper, we present laboratory measurements of the hygroscopic growth factors (HGf) and cloud condensation nuclei (CCN) activity of a series of aminium carboxylate salt aerosols, utilizing a Hygroscopicity Tandem Differential Mobility Analyzer (HTDMA) coupled to a Condensation Particle Counter (CPC) and a CCN counter. HGf measurements were conducted for size-selected aerosols with diameters ranging from 46 nm to 151 nm and at relative humidity (RH%) values ranging from 10 to 90%. In addition, we have calculated the CCN activation diameters for the aminium carboxylate aerosols and derived the hygroscopicity parameter (k or kappa) values for all species using three methods, i.e., the mixing rule approximation, HGf, and CCN results. Our results show that variations in the ratio of acid to base directly affect the activation diameter, HGf, and (k) values of the aminium carboxylate aerosols. Atmospheric implications of the variations in the chemical composition of aminium carboxylate aerosols on their cloud forming potential will be discussed.

  12. Hygroscopicity of mineral dust particles: Roles of chemical mixing state and hygroscopic conversion timescale

    NASA Astrophysics Data System (ADS)

    Sullivan, R. C.; Moore, M. J.; Petters, M. D.; Laskin, A.; Roberts, G. C.; Kreidenweis, S. M.; Prather, K. A.

    2009-05-01

    Our laboratory investigations of mineral dust particle hygroscopicity are motivated by field observations of the atmospheric processing of dust. During ACE-Asia we observed sulphate and nitrate to be strongly segregated from each other in individual aged Asian dust particles. CCN activation curves of pure calcium minerals as proxies for fresh (calcium carbonate) and aged (calcium sulphate, nitrate, chloride) dust indicate that this mixing state would cause a large fraction of aged dust particles to remain poor warm cloud nucleation potential, contrary to previous assumptions. The enrichment of oxalic acid in calcium-rich dust particles could have similar effects due to the formation of insoluble calcium oxalate. Soluble calcium nitrate and chloride reaction products are hygroscopic and will transform mineral dust into excellent CCN. Generating insoluble mineral particles wet by atomization produced particles with much higher hygroscopicity then when resuspended dry. The atomized particles are likely composed of dissolved residuals and do not properly reflect the chemistry of dry mineral powders. Aerosol flow tube experiments were employed to study the conversion of calcium carbonate into calcium nitrate via heterogeneous reaction with nitric acid, with simultaneous measurements of the reacted particles' chemistry and hygroscopicity. The timescale for this hygroscopic conversion was found to occur on the order of a few hours under tropospheric conditions. This implies that the conversion of non-hygroscopic calcite- containing dust into hygroscopic particles will be controlled by the availability of nitric acid, and not by the atmospheric residence time. Results from recent investigations of the effect of secondary coatings on the ice nucleation properties of dust particles will also be presented. The cloud formation potential of aged dust particles depends on both the quantity and form of the secondary species that have reacted or mixed with the dust. These results

  13. Influence of biomass burning on CCN number and hygroscopicity during summertime in the eastern Mediterranean

    NASA Astrophysics Data System (ADS)

    Bougiatioti, A.; Bezantakos, S.; Stavroulas, I.; Kalivitis, N.; Kokkalis, P.; Biskos, G.; Mihalopoulos, N.; Papayannis, A.; Nenes, A.

    2015-08-01

    This study investigates the CCN activity and hygroscopic properties of particles influenced by biomass burning in the eastern Mediterranean. Air masses sampled were subject to a range of atmospheric processing (several hours up to 3 days). Values of the hygroscopicity parameter, κ, were derived from cloud condensation nuclei (CCN) measurements and a Hygroscopic Tandem Differential Mobility Analyzer (HTDMA). An Aerosol Chemical Speciation Monitor (ACSM) was also used to determine the chemical composition and mass concentration of non-refractory components of the submicron aerosol fraction. During fire events, the increased organic content (and lower inorganic fraction) of the aerosol decreases the hygroscopicity parameter, κ, for all particle sizes. The reason, however, for this decrease was not the same for all size modes; smaller particle sizes appeared to be richer in less hygroscopic, less CCN-active components due to coagulation processes while larger particles become less hygroscopic during the biomass burning events due to condensation of less hygroscopic gaseous compounds. In addition, smaller particles exhibited considerable chemical dispersion (where hygroscopicity varied up to 100 % for particles of same size); larger particles, however, exhibited considerably less dispersion owing to the effects of aging and retained high levels of CCN activity. These conclusions are further supported by the observed mixing state determined by the HTDMA measurements. ACSM measurements indicate that the bulk composition reflects the hygroscopicity and chemical nature of the largest particles and a large fraction of the CCN concentrations sampled. Based on Positive Matrix Factorization (PMF) analysis of the organic ACSM spectra, CCN concentrations follow a similar trend with the BBOA component, with enhancements of CCN in biomass burning plumes ranging between 65 and 150 %, for supersaturations ranging between 0.2 and 0.7 %. Using multilinear regression, we determine the

  14. 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.

  15. Caribbean coral growth influenced by anthropogenic aerosol emissions

    NASA Astrophysics Data System (ADS)

    Kwiatkowski, Lester; Cox, Peter M.; Economou, Theo; Halloran, Paul R.; Mumby, Peter J.; Booth, Ben B. B.; Carilli, Jessica; Guzman, Hector M.

    2013-05-01

    Coral growth rates are highly dependent on environmental variables such as sea surface temperature and solar irradiance. Multi-decadal variability in coral growth rates has been documented throughout the Caribbean over the past 150-200 years, and linked to variations in Atlantic sea surface temperatures. Multi-decadal variability in sea surface temperatures in the North Atlantic, in turn, has been linked to volcanic and anthropogenic aerosol forcing. Here, we examine the drivers of changes in coral growth rates in the western Caribbean between 1880 and 2000, using previously published coral growth chronologies from two sites in the region, and a numerical model. Changes in coral growth rates over this period coincided with variations in sea surface temperature and incoming short-wave radiation. Our model simulations show that variations in the concentration of anthropogenic aerosols caused variations in sea surface temperature and incoming radiation in the second half of the twentieth century. Before this, variations in volcanic aerosols may have played a more important role. With the exception of extreme mass bleaching events, we suggest that neither climate change from greenhouse-gas emissions nor ocean acidification is necessarily the driver of multi-decadal variations in growth rates at some Caribbean locations. Rather, the cause may be regional climate change due to volcanic and anthropogenic aerosol emissions.

  16. Hygroscopicity of nanoparticles produced from homogeneous nucleation in the CLOUD experiments

    NASA Astrophysics Data System (ADS)

    Kim, J.; Ahlm, L.; Yli-Juuti, T.; Lawler, M.; Keskinen, H.; Tröstl, J.; Schobesberger, S.; Duplissy, J.; Amorim, A.; Bianchi, F.; Donahue, N. M.; Flagan, R. C.; Hakala, J.; Heinritzi, M.; Jokinen, T.; Kürten, A.; Laaksonen, A.; Lehtipalo, K.; Miettinen, P.; Petäjä, T.; Rissanen, M. P.; Rondo, L.; Sengupta, K.; Simon, M.; Tomé, A.; Williamson, C.; Wimmer, D.; Winkler, P. M.; Ehrhart, S.; Ye, P.; Kirkby, J.; Curtius, J.; Baltensperger, U.; Kulmala, M.; Lehtinen, K. E. J.; Smith, J. N.; Riipinen, I.; Virtanen, A.

    2016-01-01

    Sulfuric acid, amines and oxidized organics have been found to be important compounds in the nucleation and initial growth of atmospheric particles. Because of the challenges involved in determining the chemical composition of objects with very small mass, however, the properties of the freshly nucleated particles and the detailed pathways of their formation processes are still not clear. In this study, we focus on a challenging size range, i.e., particles that have grown to diameters of 10 and 15 nm following nucleation, and measure their water uptake. Water uptake is useful information for indirectly obtaining chemical composition of aerosol particles. We use a nanometer-hygroscopicity tandem differential mobility analyzer (nano-HTDMA) at subsaturated conditions (ca. 90 % relative humidity at 293 K) to measure the hygroscopicity of particles during the seventh Cosmics Leaving OUtdoor Droplets (CLOUD7) campaign performed at CERN in 2012. In CLOUD7, the hygroscopicity of nucleated nanoparticles was measured in the presence of sulfuric acid, sulfuric acid-dimethylamine, and sulfuric acid-organics derived from α-pinene oxidation. The hygroscopicity parameter κ decreased with increasing particle size, indicating decreasing acidity of particles. No clear effect of the sulfuric acid concentration on the hygroscopicity of 10 nm particles produced from sulfuric acid and dimethylamine was observed, whereas the hygroscopicity of 15 nm particles sharply decreased with decreasing sulfuric acid concentrations. In particular, when the concentration of sulfuric acid was 5.1 × 106 molecules cm-3 in the gas phase, and the dimethylamine mixing ratio was 11.8 ppt, the measured κ of 15 nm particles was 0.31 ± 0.01: close to the value reported for dimethylaminium sulfate (DMAS) (κDMAS ˜ 0.28). Furthermore, the difference in κ between sulfuric acid and sulfuric acid-imethylamine experiments increased with increasing particle size. The κ values of particles in the presence of

  17. Contributions of Organic Vapors to Aerosol Aging and Growth

    NASA Astrophysics Data System (ADS)

    Zhang, R.; Wang, L.; Khalizov, A.

    2009-05-01

    Atmospheric aerosols impair visibility and human health, interfere with radiative transfer, and alter cloud formation. The major contributors include sulfate and organic aerosols from anthropogenic and biogenic activities, which are produced through a multitude of complex multiphase atmospheric processes by photochemical oxidation of emitted sulfur dioxide and volatile organic compounds (VOCs) into less volatile forms and gas-to-particle conversion. Condensation of organic vapors onto the pre-existing atmospheric aerosols, followed by chemical reactions within the particles medium, is believed to be one of the major pathways that contribute to particle growth. Recent research has focused on the total mass increase on pre- existing seed particles, but the chemistry that determines the efficiency of organic uptake remains to be elucidated. This talk will focus on the growth of nano- to sub-micron sulfuric acid droplets exposed organic vapors. Experiments performed at different relative humidity and using different organic vapors (i.e., small alpha-dicarbonyls and large aldehydes) will be presented. The chemical mechanisms and size dependence of the particle growth will be demonstrated. Implications of the present results to aging and growth of aerosols under ambient conditions will be discussed.

  18. The optical properties of hygroscopic soot aggregates with water coating

    NASA Astrophysics Data System (ADS)

    Wu, Yu; Cheng, Tianhai; Zheng, Lijuan

    2014-05-01

    Anthropogenic aerosols, such as soot, have modified the Earth's radiation balance by scattering and absorbing solar and long-wave radiative transmission, which have largely influenced the global climate change since the industrial era. Based on transmission electron microscope images (TEM), soot particles are shown as the complex, fractal-like aggregate structures. In humid atmospheric environments, these soot aggregates tend to acquire a water coating, which introduces further complexity to the problem of determining the optical properties of the aggregates. The hygroscopic growth of soot aggregates is important for the aging of these absorbing aerosols, which can significantly influence the optical properties of these kinds of soot particles. In this paper, according to the specific volume fractions of soot core in the water coated soot particle, the monomers of fractal soot aggregates are modeled as semi-external mixtures (physical contact) with constant radius of soot core and variable size of water coating. The single scattering properties of these hygroscopic soot particles, such as scattering matrices, the cross sections of extinction, absorption and scattering, single scattering albedo (SSA), and asymmetry parameter (ASY), are calculated using the numerically exact superposition T-matrix method. The morphological effects are compared with different monomer numbers and fractal dimensions of the soot aggregates, as well as different size of water coating for these concentric spherical monomers. The results have shown that SSA, cross sections of extinction and absorption are increased for soot aggregates with thicker weakly absorbing coating on the monomers. It is found that the SSA of aged soot aggregates with hygroscopic grown are remarkably (~50% for volume fraction of soot aggregates is 0.5, at 0.670μm) larger than fresh soot particles without the consideration of water coating, due to the size of water coating and the morphological features, such as the

  19. 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.

  20. Atmospheric pressure flow reactor / aerosol mass spectrometer studies of tropospheric aerosol nucleat and growth kinetics. Final report, June, 2001

    SciTech Connect

    Worsnop, Douglas R.

    2001-06-01

    The objective of this program was to determine the mechanisms and rates of growth and transformation and growth processes that control secondary aerosol particles in both the clear and polluted troposphere. The experimental plan coupled an aerosol mass spectrometer (AMS) with a chemical ionization mass spectrometer to provide simultaneous measurement of condensed and particle phases. The first task investigated the kinetics of tropospheric particle growth and transformation by measuring vapor accretion to particles (uptake coefficients, including mass accommodation coefficients and heterogeneous reaction rate coefficients). Other work initiated investigation of aerosol nucleation processes by monitoring the appearance of submicron particles with the AMS as a function of precursor gas concentrations. Three projects were investigated during the program: (1) Ozonolysis of oleic acid aerosols as model of chemical reactivity of secondary organic aerosol; (2) Activation of soot particles by measurement deliquescence in the presence of sulfuric acid and water vapor; (3) Controlled nucleation and growth of sulfuric acid aerosols.

  1. CMAQ validation of optical parameters and PM2.5 based on lidar and sky radiometers: a sensitivity study of optical parameters to hygroscopic aerosols

    NASA Astrophysics Data System (ADS)

    Vladutescu, Daniela Viviana; Garofalo, Erika; Gross, Barry; Moshary, Fred; Ahmed, Samir

    2009-08-01

    With the dramatically climate changing we are facing today atmospheric monitoring is of major importance. Several atmospheric monitoring instruments are used for measuring atmospheric composition, optical coefficients, PM2.5, aerosol optical depth, size distribution, PBL height and many other parameters. However an inexpensive method of determining these parameters is by use of models and one model that depicts the aerosol dynamics in the atmosphere is the Community Multi-scale Air Quality (CMAQ) model. Our paper is focused on converting CMAQ retrieval outputs into optical coefficients that can then be comparing the lidar, AERONET and TEOM measurements performed at City College of the City University of New York . Differences between the full approach and parameterized methods such as the MALM formula used in AIR-NOW are observed and comparisons with AERONET show the full modeling is in general superior to the MALM formula.

  2. Hygroscopicity and composition of Alaskan Arctic CCN during April 2008

    NASA Astrophysics Data System (ADS)

    Moore, R. H.; Bahreini, R.; Brock, C. A.; Froyd, K. D.; Cozic, J.; Holloway, J. S.; Middlebrook, A. M.; Murphy, D. M.; Nenes, A.

    2011-08-01

    We present a comprehensive characterization of cloud condensation nuclei (CCN) sampled in the Alaskan Arctic during the 2008 Aerosol, Radiation, and Cloud Processes affecting Arctic Climate (ARCPAC) project, a component of the POLARCAT and International Polar Year (IPY) initiatives. Four distinct air mass types were sampled including relatively pristine Arctic background conditions as well as biomass burning and anthropogenic pollution plumes. Despite differences in chemical composition, inferred aerosol hygroscopicities were fairly invariant and ranged from κ = 0.1-0.3 over the atmospherically-relevant range of water vapor supersaturations studied. Analysis of the individual mass spectral m/z 43 and 44 peaks from an aerosol mass spectrometer show the organic aerosols sampled to be well-oxygenated, consistent with with long-range transport and aerosol aging processes. However, inferred hygroscopicities are less than would be predicted based on previous parameterizations of biogenic oxygenated organic aerosol, suggesting an upper limit on organic aerosol hygroscopicity above which κ is less sensitive to the O:C ratio. Most Arctic aerosol act as CCN above 0.1 % supersaturation, although the data suggest the presence of an externally-mixed, non-CCN-active mode comprising approximately 0-20 % of the aerosol number. CCN closure was assessed using measured size distributions, bulk chemical composition measurements, and assumed aerosol mixing states; CCN predictions tended toward overprediction, with the best agreement (± 0-20 %) obtained by assuming the aerosol to be externally-mixed with soluble organics. Closure also varied with CCN concentration, and the best agreement was found for CCN concentrations above 100 cm-3 with a 1.5- to 3-fold overprediction at lower concentrations.

  3. 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.

  4. Does the long-range transport of African mineral dust across the Atlantic enhance their hygroscopicity?

    NASA Astrophysics Data System (ADS)

    Denjean, Cyrielle; Caquineau, Sandrine; Desboeufs, Karine; Laurent, Benoit; Quiñones Rosado, Mariana; Vallejo, Pamela; Mayol-Bracero, Olga; Formenti, Paola

    2015-04-01

    Influence of mineral dust on radiation balance is largely dependent on their ability to interact with water. While fresh mineral dusts are highly hydrophobic, various transformation processes (coagulation, heterogeneous chemical reaction) can modify the dust physical and chemical properties during long-range transport, which, in turn, can change the dust hygroscopic properties. The model predictions of the radiative effect by mineral dust still suffer of the lack of certainty of dust hygroscopic properties, and their temporal evolution during long-range transport. We present the first direct surface measurements of the hygroscopicity of Saharan dust after long-range transport over the Atlantic Ocean, their relationship with chemical composition, their influence on particle size and shape and implications for optical properties. Particles were collected during the DUST Aging and TransporT from Africa to the Caribbean (Dust-AttaCk) campaign at the Cape San Juan Puerto Rico station in June-July 2012. Environmental scanning electron microscopy (ESEM) was used to analyze the size, shape, chemical composition and hygroscopic properties of individual particles. At different levels of concentrations in summertime, the coarse mode of atmospheric aerosols in Puerto Rico is dominated by Saharan mineral dust. Most of aged dust particles survived atmospheric transport intact with no observed internal mixture with other species and did not show hygroscopic growth up to 94% relative humidity. This is certainly due to the fact that in summertime dust is mostly transported above the marine boundary layer. A minor portion of mineral dust (approximately 19-28% by number) were involved in atmospheric heterogeneous reactions with acidic gases (likely SO2 and HCl) and sea salt aggregation. While sulfate- and chloride-coated dust remained extremely hydrophobic, dust particles in internal mixing with NaCl underwent profound changes in their hygroscopicity, therefore in size and shape. We

  5. Aerosol-induced mechanisms for cumulus congestus growth

    NASA Astrophysics Data System (ADS)

    Sheffield, Amanda M.; Saleeby, Stephen M.; Heever, Susan C.

    2015-09-01

    Tropical convection has been observed to contain three cloud modes, the middle of which is cumulus congestus clouds. Congestus clouds act to moisten the tropical atmosphere, may be mixed-phase, and on occasion surpass the freezing level inversion from where they may develop into deeper convection. This study investigates the impacts of enhanced aerosol concentrations on the growth of congestus clouds produced in idealized cloud-resolving model simulations run under a state of radiative convective equilibrium (RCE). High-resolution, long-duration simulations were completed using the Regional Atmospheric Modeling System (RAMS). Aerosol concentrations between 2 and 4 km above ground level were varied from clean to polluted conditions in order to represent the advection of Saharan dust over the Atlantic Ocean. The congestus populations within each aerosol simulation are statistically analyzed using 10 days of model output after the simulation reaches RCE. Results indicate that congestus in more polluted conditions produce greater amounts of cloud water and ice mass, enhanced updraft strengths, and an increase in the number of congestus cloud tops that extend above the freezing level. Enhanced vapor depositional growth on the populations of more numerous, smaller cloud droplets in the polluted conditions, and the subsequent increase in latent heat release in the warm phase regions of the cloud, is found to be important factors in convective invigoration of these cloud systems. Aerosol feedbacks associated with cold pools and condensate loading also influence the updraft strength and act in opposition to the warm phase invigoration processes.

  6. Hygroscopicity and composition of Alaskan Arctic CCN during April 2008

    NASA Astrophysics Data System (ADS)

    Moore, R. H.; Bahreini, R.; Brock, C. A.; Froyd, K. D.; Cozic, J.; Holloway, J. S.; Middlebrook, A. M.; Murphy, D. M.; Nenes, A.

    2011-11-01

    We present a comprehensive characterization of cloud condensation nuclei (CCN) sampled in the Alaskan Arctic during the 2008 Aerosol, Radiation, and Cloud Processes affecting Arctic Climate (ARCPAC) project, a component of the POLARCAT and International Polar Year (IPY) initiatives. Four distinct air mass types were sampled including a cleaner Arctic background and a relatively pristine sea ice boundary layer as well as biomass burning and anthropogenic pollution plumes. Despite differences in chemical composition, inferred aerosol hygroscopicities were fairly invariant and ranged from κ = 0.1-0.3 over the atmospherically-relevant range of water vapor supersaturations studied. Organic aerosols sampled were found to be well-oxygenated, consistent with long-range transport and aerosol aging processes. However, inferred hygroscopicities are less than would be predicted based on previous parameterizations of biogenic oxygenated organic aerosol, suggesting an upper limit on organic aerosol hygroscopicity above which κ is less sensitive to the O:C ratio. Most Arctic aerosols act as CCN above 0.1 % supersaturation, although the data suggest the presence of an externally-mixed, non-CCN-active mode comprising approximately 0-20% of the aerosol number. CCN closure was assessed using measured size distributions, bulk chemical composition, and assumed aerosol mixing states; CCN predictions tended toward overprediction, with the best agreement (±0-20 %) obtained by assuming the aerosol to be externally-mixed with soluble organics. Closure also varied with CCN concentration, and the best agreement was found for CCN concentrations above 100 cm-3 with a 1.5- to 3-fold overprediction at lower concentrations.

  7. Final Report "Nucleation and Growth of Atmospheric Aerosols" DOE Grant No. DE-FG02-98ER62556

    SciTech Connect

    McMurry, Peter H.; Eisele, Fred L.

    2005-06-02

    Research that was supported by this contract has contributed substantially to progress in our understanding of new particle formation in the atmosphere. Objectives included the development of new measurement methods, the application of those new instrument systems in atmospheric field studies, and the interpretation of results from those studies. We developed the "Nano TDMA" to measure the hygroscopicity and volatility of 4-20 nm particles. We used this instrument system to characterize properties of atmospheric particles in the Atlanta atmosphere in July/August 2002 as well as to study properties of diesel exhaust particles. We also developed the thermal desorption chemical ionization mass spectrometer (TDCIMS) to measure the chemical composition of nanoparticles as small as 7 nm with a time resolution of 10-20 minutes. The TDCIMS is currently the only instrument that can perform such measurements. Atmospheric field measurements were carried out in Atlanta (July/August 2002; we refer to this as the ANARChE study) and in Boulder, CO (2003/04). In the ANARChE study we measured, for the first time, the composition of freshly nucleated particles as small as 7 nm using the TDCIMS. The ANARChE study also included the first nano-TDMA measurements of the volatility and hygroscopicity of freshly nucleated particles as small as 4 nm. Other parameters that were measured included particle size distributions (3 nm-2 µm), and sulfuric acid and ammonia concentrations. Key discoveries from the ANARChE study are: (1) freshly nucleated particles in Atlanta consist primarily of ammonium and sulfate; evidence for significant amounts of other species such as organics and nitrates was not found; (2) new particle formation occurs when rates of cluster loss to preexisting particles are small compared to rates of lost to the next larger cluster size by growth; a dimensionless parameter L describes the ratio of these rates, and measurements showed that new particle formation was always

  8. Characterization of particle hygroscopicity by Raman lidar: Selected case studies from the convective and orographically-induced precipitation study

    NASA Astrophysics Data System (ADS)

    Stelitano, Dario; Di Girolamo, Paolo; Summa, Donato

    2013-05-01

    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. 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 vapor 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). The present analysis is focused on selected case studies characterized by the presence of different aerosol types with different hygroscopic behavior. The observed behavior, dependent upon aerosol composition, may range from hygrophobic to strongly hygroscopic.

  9. Organic Aerosol Nucleation and Growth at the CERN CLOUD chamber

    NASA Astrophysics Data System (ADS)

    Tröstl, Jasmin; Lethipalo, Katrianne; Bianchi, Federico; Sipilä, Mikko; Nieminen, Tuomo; Wagner, Robert; Frege, Carla; Simon, Mario; Weingartner, Ernest; Gysel, Martin; Dommen, Josef; Baltensperger, Urs

    2014-05-01

    It is well known that atmospheric aerosols influence the climate by changing Earth's radiation balance (IPCC 2007 and 2013). Recent models have shown (Merikanto et al. 2009) that aerosol nucleation is one of the biggest sources of low level cloud condensation nuclei. Still, aerosol nucleation and growth are not fully understood. The driving force of nucleation and growth is sulfuric acid. However ambient nucleation and growth rates cannot be explained by solely sulfuric acid as precursor. Recent studies have shown that only traces of precursors like ammonia and dimethylamine enhance the nucleation rates dramatically (Kirkby et al. 2011, Almeida et al., 2013). Thus the role of different aerosol precursor needs to be studied not only in ambient but also in very well controlled chamber experiments. The CLOUD (Cosmics Leaving OUtdoor Droplets) experiment enables conducting experiments very close to atmospheric conditions and with a very low contaminant background. The latest CLOUD experiments focus on the role of organics in aerosol nucleation and growth. For this purpose, numerous experiments with alpha-pinene have been conducted at the CERN CLOUD chamber. Several state-of-the-art instruments were used to cover the whole complexity of the experiment. Chamber conditions were set to 40% relative humidity and 5° C. Atmospheric concentrations of SO2, O3, HONO, H2O and alpha-pinene were injected to the chamber. Different oxidation conditions were used, yielding different levels of oxidized organics: (1) OH radicals, (2) Ozone with the OH scavenger H2 (pure ozonolysis) and (3) both. SO2 was injected to allow for sulfuric acid production. Optical UV fibers were used to enable photochemical reactions. A high field cage (30 kV) can be turned on to remove all charged particles in the chamber to enable completely neutral conditions. Comparing neutral conditions to the beam conditions using CERN's proton synchrotron, the fraction of ion-induced nucleation can be studied. Using

  10. Comparison of Hygroscopicity, Volatility, and Mixing State of Submicrometer Particles between Cruises over the Arctic Ocean and the Pacific Ocean.

    PubMed

    Kim, Gibaek; Cho, Hee-Joo; Seo, Arom; Kim, Dohyung; Gim, Yeontae; Lee, Bang Yong; Yoon, Young Jun; Park, Kihong

    2015-10-20

    Ship-borne measurements of ambient aerosols were conducted during an 11 937 km cruise over the Arctic Ocean (cruise 1) and the Pacific Ocean (cruise 2). A frequent nucleation event was observed during cruise 1 under marine influence, and the abundant organic matter resulting from the strong biological activity in the ocean could contribute to the formation of new particles and their growth to a detectable size. Concentrations of particle mass and black carbon increased with increasing continental influence from polluted areas. During cruise 1, multiple peaks of hygroscopic growth factor (HGF) of 1.1-1.2, 1.4, and 1.6 were found, and higher amounts of volatile organic species existed in the particles compared to that during cruise 2, which is consistent with the greater availability of volatile organic species caused by the strong oceanic biological activity (cruise 1). Internal mixtures of volatile and nonhygroscopic organic species, nonvolatile and less-hygroscopic organic species, and nonvolatile and hygroscopic nss-sulfate with varying fractions can be assumed to constitute the submicrometer particles. On the basis of elemental composition and morphology, the submicrometer particles were classified into C-rich mixture, S-rich mixture, C/S-rich mixture, Na-rich mixture, C/P-rich mixture, and mineral-rich mixture. Consistently, the fraction of biological particles (i.e., P-containing particles) increased when the ship traveled along a strongly biologically active area. PMID:26389581

  11. Organic aerosol effects on fog droplet spectra

    NASA Astrophysics Data System (ADS)

    Ming, Yi; Russell, Lynn M.

    2004-05-01

    Organic aerosol alters cloud and fog properties through surface tension and solubility effects. This study characterizes the role of organic compounds in affecting fog droplet number concentration by initializing and comparing detailed particle microphysical simulations with two field campaigns in the Po Valley. The size distribution and chemical composition of aerosol were based on the measurements made in the Po Valley Fog Experiments in 1989 and 1998-1999. Two types of aerosol with different hygroscopicity were considered: the less hygroscopic particles, composed mainly of organic compounds, and the more hygroscopic particles, composed mainly of inorganic salts. The organic fraction of aerosol mass was explicitly modeled as a mixture of seven soluble compounds [, 2001] by employing a functional group-based thermodynamic model [, 2002]. Condensable gases in the vapor phase included nitric acid, sulfuric acid, and ammonia. The maximum supersaturation in the simulation is 0.030% and is comparable to the calculation by [1992] inferred from measured residual particle fractions. The minimum activation diameters of the less and more hygroscopic particles are 0.49 μm and 0.40 μm, respectively. The predicted residual particle fractions are in agreement with measurements. The organic components of aerosol account for 34% of the droplet residual particle mass and change the average droplet number concentration by -10-6%, depending on the lowering of droplet surface tension and the interactions among dissolving ions. The hygroscopic growth of particles due to the presence of water-soluble organic compounds enhances the condensation of nitric acid and ammonia due to the increased surface area, resulting in a 9% increase in the average droplet number concentration. Assuming ideal behavior of aqueous solutions of water-soluble organic compounds overestimates the hygroscopic growth of particles and increases droplet numbers by 6%. The results are sensitive to microphysical

  12. Nucleation and growth processes of atmospheric aerosols and clouds

    SciTech Connect

    Schwartz, S.E.; McGraw, R.L.

    1995-11-01

    This project seeks to gain enhanced understanding of the rate of formation and growth of new particles and of cloud droplets as a function of pertinent controlling atmospheric variables, thereby permitting accurate representation of these processes in climate models. Aerosol size distributions are shaped by complex nucleation and growth and mixing processes that are difficult to represent in models, due to the need to accurately represent the evaporation/growth kinetics for each of the billions of discrete cluster sizes in the growth sequence, ranging from molecular clusters to particles of radius of several tenths of a micrometer or greater. A potentially very powerful means of solving this problem may be given by the method of moments (MOM), which tracks the time dependence of just the lower-order radial moments of the size distribution without requiring knowledge of the distribution itself.

  13. Hygroscopic properties of newly formed ultrafine particles at an urban site surrounded by deciduous forest (Sapporo, northern Japan) during the summer of 2011

    NASA Astrophysics Data System (ADS)

    Jung, J.; Kawamura, K.

    2014-07-01

    To investigate the hygroscopic properties of ultrafine particles during new particle formation events, the hygroscopic growth factors of size-segregated atmospheric particles were measured at an urban site in Sapporo, northern Japan, during the summer of 2011. The hygroscopic growth factor at 85 % relative humidity [g(85%)] of freshly formed nucleation mode particles was 1.11 to 1.28 (average: 1.16 ± 0.06) at a dry particle diameter (Dp) centered on 20 nm, which is equivalent to 1.17 to 1.35 (1.23 ± 0.06) at a dry Dp centered on 100 nm after considering the Kelvin effect. These values are comparable with those of secondary organic aerosols, suggesting that low-volatility organic vapors are important to the burst of nucleation mode particles. The equivalent g(85%) at a dry Dp of 100 nm for nucleated particles that have grown to Aitken mode sizes (1.24 to 1.34; average: 1.30 ± 0.04) were slightly higher than those of newly formed nucleation mode particles, suggesting that the growth of freshly formed nucleation mode particles to the Aitken mode size can be subjected to condensation of not only low-volatility organic vapors, but also water-soluble inorganic species. Based on this result, and previous measurement of radiocarbon in aerosols, we suggest that the burst of nucleation mode particles and their subsequent growth were highly affected by biogenic organic emissions at this measurement site, which is surrounded by deciduous forest. Gradual increases in mode diameter after the burst of nucleation mode particles were observed under southerly wind conditions, with a dominant contribution of intermediately hygroscopic particles. However, sharp increases in mode diameter were observed when the wind direction shifted to northwesterly or northeasterly, with a sharp increase in the highly hygroscopic particle fraction of the Aitken mode particles, indicating that the hygroscopic growth factor of newly formed particles is perturbed by the local winds that deliver

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

    NASA Astrophysics Data System (ADS)

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

    2001-12-01

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

  15. Temporal Variation of Aerosol Properties at a Rural Continental Site and Study of Aerosol Evolution through Growth Law Analysis

    NASA Technical Reports Server (NTRS)

    Wang, Jian; Collins, Don; Covert, David; Elleman, Robert; Ferrare, Richard A.; Gasparini, Roberto; Jonsson, Haflidi; Ogren, John; Sheridan, Patrick; Tsay, Si-Chee

    2006-01-01

    Aerosol size distributions were measured by a Scanning Mobility Particle Sizer (SMPS) onboard the CIRPAS Twin Otter aircraft during 16 flights at the Southern Great Plains (SGP) site in northern central Oklahoma as part of the Aerosol Intensive Operation period in May, 2003. During the same period a second SMPS was deployed at a surface station and provided continuous measurements. Combined with trace gas measurements at the SGP site and back-trajectory analysis, the aerosol size distributions provided insights into the sources of aerosols observed at the SGP site. High particle concentrations, observed mostly during daytime, were well correlated with the sulfur dioxide (SO2) mixing ratios, suggesting nucleation involving sulfuric acid is likely the main source of newly formed particles at the SGP. Aerosols within plumes originating from wildfires in Central America were measured at the surface site. Vertically compact aerosol layers, which can be traced back to forest fires in East Asia, were intercepted at altitudes over 3000 meters. Analyses of size dependent particle growth rates for four periods during which high cloud coverage was observed indicate growth dominated by volume controlled reactions. Sulfate accounts for 50% to 72% of the increase in aerosol volume concentration; the rest of the volume concentration increase was likely due to secondary organic species. The growth law analyses and meteorological conditions indicate that the sulfate was produced mainly through aqueous oxidation of SO2 in clouds droplets and hydrated aerosol particles.

  16. Temporal variation of aerosol properties at a rural continental site and study of aerosol evolution through growth law analysis

    NASA Astrophysics Data System (ADS)

    Wang, Jian; Collins, Don; Covert, David; Elleman, Robert; Ferrare, Richard A.; Gasparini, Roberto; Jonsson, Haflidi; Ogren, John; Sheridan, Patrick; Tsay, Si-Chee

    2006-09-01

    Aerosol size distributions were measured by a Scanning Mobility Particle Sizer (SMPS) on board the CIRPAS Twin Otter aircraft during 16 flights at the Southern Great Plains (SGP) site in northern central Oklahoma as part of the Aerosol Intensive Operation period in May 2003. During the same period a second SMPS was deployed at a surface station and provided continuous measurements. Combined with trace gas measurements at the SGP site and back trajectory analysis, the aerosol size distributions provided insights into the sources of aerosols observed at the SGP site. High particle concentrations, observed mostly during daytime, were well correlated with the sulfur dioxide (SO2) mixing ratios, suggesting nucleation involving sulfuric acid is likely the main source of newly formed particles at the SGP. Aerosols within plumes originating from wildfires in Central America were measured at the surface site. Vertically compact aerosol layers, which can be traced back to forest fires in East Asia, were intercepted at altitudes over 3000 m. Analyses of size-dependent particle growth rates for four periods during which high cloud coverage was observed indicate growth dominated by volume controlled reactions. Sulfate accounts for 50% to 72% of the increase in aerosol volume concentration; the rest of the volume concentration increase was likely due to secondary organic species. The growth law analyses and meteorological conditions indicate that the sulfate was produced mainly through aqueous oxidation of SO2 in clouds droplets and hydrated aerosol particles.

  17. Measuring Mass-Based Hygroscopicity of Atmospheric Particles through in Situ Imaging.

    PubMed

    Piens, Dominique S; Kelly, Stephen T; Harder, Tristan H; Petters, Markus D; O'Brien, Rachel E; Wang, Bingbing; Teske, Ken; Dowell, Pat; Laskin, Alexander; Gilles, Mary K

    2016-05-17

    Quantifying how atmospheric particles interact with water vapor is critical for understanding the effects of aerosols on climate. We present a novel method to measure the mass-based hygroscopicity of particles while characterizing their elemental and carbon functional group compositions. Since mass-based hygroscopicity is insensitive to particle geometry, it is advantageous for probing the hygroscopic behavior of atmospheric particles, which can have irregular morphologies. Combining scanning electron microscopy with energy dispersive X-ray analysis (SEM/EDX), scanning transmission X-ray microscopy (STXM) analysis, and in situ STXM humidification experiments, this method was validated using laboratory-generated, atmospherically relevant particles. Then, the hygroscopicity and elemental composition of 15 complex atmospheric particles were analyzed by leveraging quantification of C, N, and O from STXM, and complementary elemental quantification from SEM/EDX. We found three types of hygroscopic responses, and correlated high hygroscopicity with Na and Cl content. The mixing state of 158 other particles from the sample broadly agreed with those of the humidified particles, indicating the potential to infer atmospheric hygroscopic behavior from a selected subset of particles. These methods offer unique quantitative capabilities to characterize and correlate the hygroscopicity and chemistry of individual submicrometer atmospheric particles. PMID:27088454

  18. Measuring mass-based hygroscopicity of atmospheric particles through in situ imaging

    DOE PAGESBeta

    Piens, Dominique S.; Kelly, Stephen T.; Harder, Tristan H.; Petters, Markus D.; O’Brien, Rachel E.; Wang, Bingbing; Teske, Ken; Dowell, Pat; Laskin, Alexander; Gilles, Mary K.

    2016-04-18

    Quantifying how atmospheric particles interact with water vapor is critical for understanding the effects of aerosols on climate. We present a novel method to measure the mass-based hygroscopicity of particles while characterizing their elemental and carbon functional group compositions. Since mass-based hygroscopicity is insensitive to particle geometry, it is advantageous for probing the hygroscopic behavior of atmospheric particles, which can have irregular morphologies. Combining scanning electron microscopy with energy dispersive X-ray analysis (SEM/EDX), scanning transmission X-ray microscopy (STXM) analysis, and in situ STXM humidification experiments, this method was validated using laboratory-generated, atmospherically relevant particles. Then, the hygroscopicity and elemental compositionmore » of 15 complex atmospheric particles were analyzed by leveraging quantification of C, N, and O from STXM, and complementary elemental quantification from SEM/EDX. We found three types of hygroscopic responses, and correlated high hygroscopicity with Na and Cl content. The mixing state of 158 other particles from the sample broadly agreed with those of the humidified particles, indicating the potential to infer atmospheric hygroscopic behavior from a selected subset of particles. As a result, these methods offer unique quantitative capabilities to characterize and correlate the hygroscopicity and chemistry of individual submicrometer atmospheric particles.« less

  19. Nonequilibrium atmospheric secondary organic aerosol formation and growth.

    PubMed

    Perraud, Véronique; Bruns, Emily A; Ezell, Michael J; Johnson, Stanley N; Yu, Yong; Alexander, M Lizabeth; Zelenyuk, Alla; Imre, Dan; Chang, Wayne L; Dabdub, Donald; Pankow, James F; Finlayson-Pitts, Barbara J

    2012-02-21

    Airborne particles play critical roles in air quality, health effects, visibility, and climate. Secondary organic aerosols (SOA) formed from oxidation of organic gases such as α-pinene account for a significant portion of total airborne particle mass. Current atmospheric models typically incorporate the assumption that SOA mass is a liquid into which semivolatile organic compounds undergo instantaneous equilibrium partitioning to grow the particles into the size range important for light scattering and cloud condensation nuclei activity. We report studies of particles from the oxidation of α-pinene by ozone and NO(3) radicals at room temperature. SOA is primarily formed from low-volatility ozonolysis products, with a small contribution from higher volatility organic nitrates from the NO(3) reaction. Contrary to expectations, the particulate nitrate concentration is not consistent with equilibrium partitioning between the gas phase and a liquid particle. Rather the fraction of organic nitrates in the particles is only explained by irreversible, kinetically determined uptake of the nitrates on existing particles, with an uptake coefficient that is 1.6% of that for the ozonolysis products. If the nonequilibrium particle formation and growth observed in this atmospherically important system is a general phenomenon in the atmosphere, aerosol models may need to be reformulated. The reformulation of aerosol models could impact the predicted evolution of SOA in the atmosphere both outdoors and indoors, its role in heterogeneous chemistry, its projected impacts on air quality, visibility, and climate, and hence the development of reliable control strategies. PMID:22308444

  20. Nonequilibrium atmospheric secondary organic aerosol formation and growth

    PubMed Central

    Perraud, Véronique; Bruns, Emily A.; Ezell, Michael J.; Johnson, Stanley N.; Yu, Yong; Alexander, M. Lizabeth; Zelenyuk, Alla; Imre, Dan; Chang, Wayne L.; Dabdub, Donald; Pankow, James F.; Finlayson-Pitts, Barbara J.

    2012-01-01

    Airborne particles play critical roles in air quality, health effects, visibility, and climate. Secondary organic aerosols (SOA) formed from oxidation of organic gases such as α-pinene account for a significant portion of total airborne particle mass. Current atmospheric models typically incorporate the assumption that SOA mass is a liquid into which semivolatile organic compounds undergo instantaneous equilibrium partitioning to grow the particles into the size range important for light scattering and cloud condensation nuclei activity. We report studies of particles from the oxidation of α-pinene by ozone and NO3 radicals at room temperature. SOA is primarily formed from low-volatility ozonolysis products, with a small contribution from higher volatility organic nitrates from the NO3 reaction. Contrary to expectations, the particulate nitrate concentration is not consistent with equilibrium partitioning between the gas phase and a liquid particle. Rather the fraction of organic nitrates in the particles is only explained by irreversible, kinetically determined uptake of the nitrates on existing particles, with an uptake coefficient that is 1.6% of that for the ozonolysis products. If the nonequilibrium particle formation and growth observed in this atmospherically important system is a general phenomenon in the atmosphere, aerosol models may need to be reformulated. The reformulation of aerosol models could impact the predicted evolution of SOA in the atmosphere both outdoors and indoors, its role in heterogeneous chemistry, its projected impacts on air quality, visibility, and climate, and hence the development of reliable control strategies. PMID:22308444

  1. Results of the South African Cloud-Seeding Experiments Using Hygroscopic Flares.

    NASA Astrophysics Data System (ADS)

    Mather, G. K.; Terblanche, D. E.; Steffens, F. E.; Fletcher, L.

    1997-11-01

    A new method of seeding convective clouds for the purpose of augmenting rainfall is being developed in South Africa. Flares that produce small salt particles (0.5-m mean diameter) are attached to the trailing edge of the wings of seeding aircraft and ignited in updrafts below the cloud base of convective storms. This method of delivery overcomes most of the difficulties encountered in the handling and the use of hygroscopic materials, difficulties that made seeding with ice nuclei (AgI) a more attractive option.The research that has led to the development of this new technique was prompted by an encounter with a storm with dramatically altered microphysics that was growing over a Kraft paper mill in the research area. Hygroscopic seeding flares were subsequently developed, and seeding trials began in October 1990. Successful seeding trials quickly led to the design and execution of a randomized convective cloud-seeding experiment, the results of which show convincing evidence of increases in the radar-measured rain mass from seeded storms when compared to the control or unseeded storms.Heightened reflectivities aloft seen by the real-time storm-tracking software and observed in the exploratory analysis raises the possibility of developing a radar-measured seeding algorithm that can recognize in almost real time a successful convective seeding event. The implications of such a development would have far-reaching effects on the conduct of future convective cloud-seeding experiments and operations.The authors' seeding hypothesis postulates that the hygroscopic seeding at cloud base accelerates the growth of large hydrometeors in the treated clouds, which harvest more of the available supercooled water before it is expelled into the anvils by the strong updrafts that are a characteristic of the local storms, thereby increasing the efficiency of the rainfall process. The validity of this hypothesis is supported by microphysical measurements made from an instrumented

  2. Contribution of Organic Vapors to the Growth of Secondary Aerosols

    NASA Astrophysics Data System (ADS)

    Wang, L.; Khalizov, A.; Zhang, R.

    2008-12-01

    Processes governing the growth of atmospheric aerosols represent an important aspect of anthropogenic climate forcing but remain poorly understood. Condensation of organic vapors onto the pre-existing atmospheric aerosols, potentially followed by chemical reactions within the particles medium, is believed to be one of the major pathways that contribute to particle growth. Recent research has focused on the total mass increase on pre-existing seed particles, but the chemistry that determines the efficiency of organic uptake remains to be elucidated. In this study, attenuated total reflection- Fourier transform infrared spectroscopy (ATR-FT-IR) was used to study the formation of new chemical bonds in the sub-micron sulfuric acid droplets deposited on ATR crystal and subjected to exposure to organic vapors (2,4-hexadienal and glyoxal). The observation of new functional groups, together with the dependence of the absorption intensity on the relative humidity, indicates that the uptake of 2,4-hexadienal is through an aldol condensation reaction and uptake of glyoxal is an acid-catalyzed hydration followed by self-reaction of hydrated and carbonyl forms to form cyclic acetal structures. The evolvement of infrared absorption features also suggests that the uptake of both compounds is at least partly reversible.

  3. Water uptake of clay and desert dust aerosol particles at sub- and supersaturated water vapor conditions

    SciTech Connect

    Herich, Hanna; Tritscher, Torsten; Wiacek, Aldona; Gysel, Martin; Weingartner, E.; Lohmann, U.; Baltensperger, Urs; Cziczo, Daniel J.

    2009-11-01

    Airborne mineral dust particles serve as cloud condensation nuclei (CCN), thereby influencing the formation and properties of warm clouds. It is therefore of particular interest how dust aerosols with different mineralogy behave when exposed to high relative humidity (RH) or supersaturation with respect to liquid water similar to atmospheric conditions. In this study the sub-saturated hygroscopic growth and the supersaturated cloud condensation nucleus activity of pure clays and real desert dust aerosols was determined using a hygroscopicity tandem differential mobility analyzer (HTDMA) and a cloud condensation nuclei counter (CCNC), respectively. Five different illite, montmorillonite and kaolinite clay samples as well as three desert dust samples (Saharan dust (SD), Chinese dust (CD) and Arizona test dust (ATD)) were used. Aerosols were generated both with a wet and a dry disperser and the water uptake was parameterized via the hygroscopicity parameter, κ. The hygroscopicity of dry generated dust aerosols was found to be negligible when compared to processed atmospheric aerosols, with CCNC derived κ values between 0.00 and 0.02. The latter value can be idealized as a particle consisting of 96.7% (by volume) insoluble material and ~3.3% ammonium sulfate. Pure clay aerosols were found to be generally less hygroscopic than real desert dust particles. All illite and montmorillonite samples had κ~0.003, kaolinites were least hygroscopic and had κ=0.001. SD (κ=0.023) was found to be the most hygroscopic dry-generated desert dust followed by CD (κ=0.007) and ATD (κ=0.003). Wet-generated dust showed an increased water uptake when compared to dry-generated samples. This is considered to be an artifact introduced by redistribution of soluble material between the particles while immersed in an aqueous medium during atomization, thus indicating that specification of the generation method is critically important when presenting such data. Any atmospheric processing of

  4. Measurement of the Hygroscopicity and Wet Removal of Black-Carbon-Containing Particles in the Urban Atmosphere of Tokyo

    NASA Astrophysics Data System (ADS)

    Ohata, Sho; Moteki, Nobuhiro; Mori, Tatsuhiro; Koike, Makoto; Schwarz, Joshua; Takami, Akinori; Kondo, Yutaka

    2015-04-01

    Megacities are very large, concentrated anthropogenic sources of black carbon (BC) aerosols. Freshly emitted BC particles inside megacities affect local air quality and regional and global climate. The microphysical properties (e.g., number size distribution, coating thickness, and hygroscopicity) of atmospheric BC-containing particles are important because their efficiency of wet removal from the atmosphere can be highly dependent on these properties. In this study, we developed a method for independent measurement of the hygroscopicity of BC-free and BC-containing particles, and then applied it to the ambient observation in the urban atmosphere of Tokyo. A single particle soot photometer (SP2) was modified as a humidified-SP2, which quantifies the BC-core mass (BC content within a BC-containing particle) and optical diameter of individual aerosol particles, under controlled relative humidity (RH), by detecting both the laser-induced incandescence emitted and laser light scattered from each particle (Schwarz et al., 2014, Journal of Aerosol Science). Measurements of growth factor (GF) and hygroscopicity parameter κ for BC-free and BC-containing particles can be achieved by combining an aerosol particle mass analyzer with the newly developed humidified-SP2. This method was tested in the laboratory and then employed in ambient observations in summer 2014. The ambient measurements were made while also measuring number size distribution of BC cores in rainwater with a nebulizer-SP2 system. Throughout the observation period, for BC-containing particles with a dry diameter of about 200 nm, the particles with smaller BC fractions tended to represent greater water uptake, and the number fraction of the less hygroscopic (GF < 1.2 at 85% RH) BC-containing particles was more than 70% of the total BC-containing particles. The measured average number size distribution of BC cores in rainwater was larger than that in the surface air before precipitation began, and the

  5. Hygroscopic properties and cloud condensation nuclei activation of limonene-derived organosulfates and their mixtures with ammonium sulfate

    NASA Astrophysics Data System (ADS)

    Hansen, A. M. K.; Hong, J.; Raatikainen, T.; Kristensen, K.; Ylisirniö, A.; Virtanen, A.; Petäjä, T.; Glasius, M.; Prisle, N. L.

    2015-12-01

    Organosulfates have been observed as constituents of atmospheric aerosols in a wide range of environments; however their hygroscopic properties remain uncharacterised. Here, limonene-derived organosulfates with a molecular weight of 250 Da (L-OS 250) were synthesised and used for simultaneous measurements with a hygroscopicity tandem differential mobility analyser (H-TDMA) and a cloud condensation nuclei counter (CCNC) to determine the hygroscopicity parameter, κ, for pure L-OS 250 and mixtures of L-OS 250 with ammonium sulfate (AS) over a wide range of humidity conditions. The κ values derived from measurements with H-TDMA decreased with increasing particle dry diameter for all chemical compositions investigated, indicating that κH-TDMA depends on particle diameter and/or surface effects; however, it is not clear if this trend is statistically significant. For pure L-OS 250, κ was found to increase with increasing relative humidity, indicating dilution/solubility effects to be significant. Discrepancies in κ between the sub- and supersaturated measurements were observed for L-OS 250, whereas κ of AS and mixed L-OS 250/AS were similar. This discrepancy was primarily ascribed to limited dissolution of L-OS 250 at subsaturated conditions. In general, hygroscopic growth factor, critical particle diameter and κ for the mixed L-OS 250/AS particles converged towards the values of pure AS for mixtures with ≥ 20 % w / w AS. Surface tension measurements of bulk aqueous L-OS 250/AS solutions showed that L-OS 250 was indeed surface active, as expected from its molecular structure, decreasing the surface tension of solutions with 24 % from the pure water value at a L-OS 250 concentration of 0.0025 mol L-1. Based on these surface tension measurements, we present the first concentration-dependent parametrisation of surface tension for aqueous L-OS 250, which was implemented to different process-level models of L-OS 250 hygroscopicity and CCN activation. The values of κ

  6. Hygroscopic properties and cloud condensation nuclei activation of limonene-derived organosulfates and their mixtures with ammonium sulfate

    NASA Astrophysics Data System (ADS)

    Hansen, A. M. K.; Hong, J.; Raatikainen, T.; Kristensen, K.; Ylisirniö, A.; Virtanen, A.; Petäjä, T.; Glasius, M.; Prisle, N. L.

    2015-06-01

    Even though organosulfates have been observed as constituents of atmospheric aerosols in a wide range of environments spanning from the subtropics to the high Arctic, their hygroscopic properties have not been investigated prior to this study. Here, limonene-derived organosulfates with a molecular weight of 250 Da (L-OS 250) were synthesized and used for simultaneous measurements with a Hygroscopicity Tandem Differential Mobility Analyzer (H-TDMA) and a Cloud Condensation Nuclei Counter (CCNC) to determine the hygroscopicity parameter, κ, for pure L-OS 250 and mixtures of L-OS 250 with ammonium sulfate (AS) over a wide range of humidity conditions. The κ values derived from measurements with H-TDMA decreased with increasing particle dry size for all chemical compositions investigated, indicating size dependency and/or surface effects. For pure L-OS 250, κ was found to increase with increasing relative humidity, indicating dilution/solubility effects to be significant. Discrepancies in κ between the sub- and supersaturated measurements were observed for L-OS 250, whereas κ of AS and mixed L-OS 250/AS were similar. This discrepancy was primarily ascribed to limited dissolution of L-OS 250 at subsaturated conditions. In general, hygroscopic growth factor, critical activation diameter and κ for the mixed L-OS 250/AS particles converged towards the values of pure AS for mixtures with ≥ 20 % w/w AS. Surface tension measurements of bulk aqueous L-OS 250/AS solutions showed that L-OS 250 was indeed surface active, as expected from its molecular structure, decreasing the surface tension of solutions with 24 % from the pure water-value at a L-OS 250 concentration of 0.0025 mol L-1. Based on these surface tension measurements, we present the first concentration-dependent parametrisation of surface tension for aqueous L-OS 250, which was implemented to different process-level models of L-OS 250 hygroscopicity and CCN activation. The values of κ obtained from the

  7. Aerosol-nutrient-induced picoplankton growth in Lake Tahoe

    NASA Astrophysics Data System (ADS)

    Mackey, Katherine R. M.; Hunter, Deborah; Fischer, Emily V.; Jiang, Yilun; Allen, Brant; Chen, Ying; Liston, Anne; Reuter, John; Schladow, Geoff; Paytan, Adina

    2013-07-01

    Tahoe is an oligotrophic lake appreciated for its transparent waters, yet the Lake's clarity has been declining for several decades due in part to eutrophication. At the same time, a shift from nitrogen (N) toward phosphorus (P) limitation of phytoplankton has occurred that could be due to atmospheric deposition of nutrients with high N:P ratios. Atmospheric particle samples collected during 2005-2006 had a mean soluble N:P ratio of 192:1, well above the Redfield ratio of 16:1 typically required by phytoplankton. Samples collected during the Angora Fire that occurred in 2007 were particularly enriched in N relative to P, with a mean ratio >2800:1. A bioassay incubation experiment was conducted using locally collected atmospheric total suspended particulate (TSP) matter. TSP samples with high ammonium (NH4+) and low P content favored the growth of picoplankton (cells <3 µm) and opportunistic filamentous cyanobacteria, whereas larger nanophytoplankton (cells 3-20 µm) were better competitors when more P was available. Picoplankton growth can increase primary productivity without causing a large increase in chlorophyll (chl a) or biomass. Aerosol-nutrient-induced picoplankton growth (together with shifts in grazing dynamics and stratification trends) may contribute to the uncoupling between primary productivity, chl a, and biomass that has been observed in Lake Tahoe in the last several decades and, in particular, following the Wheeler and Angora Fires. The chemical composition of aerosols has a marked impact on ecosystem dynamics in Lake Tahoe with potential consequences to lake productivity and microbial community dynamics.

  8. Hygroscopic properties of volcanic ash

    NASA Astrophysics Data System (ADS)

    Lathem, T. L.; Kumar, P.; Nenes, A.; Dufek, J.; Sokolik, I. N.; Trail, M.; Russell, A.

    2011-06-01

    Limited observational data exists on the physical interactions between volcanic ash particles and water vapor; yet it is thought that these interactions can strongly impact the microphysical evolution of ash, with implications for its atmospheric lifetime and transport, as well as formation of water and ice clouds. In this study, we investigate for the first time, the hygroscopic properties of ultra-fine volcanic ash (<125 μm diameter) from the eruptions of Mt. St. Helens in 1980, El Chichón in 1982, Tungurahua in 2006, Chaitén in 2008, Mt. Redoubt in 2009, and Eyjafjallajökull in 2010. The hygroscopicity of the ash particles is quantified by their ability to uptake water and nucleate into cloud drops under controlled levels of water vapor supersaturation. Evidence presented strongly suggests that ash uptakes water efficiently via adsorption and a simple parameterization of ash hygroscopicity is developed for use in ash plume and atmospheric models.

  9. Urban and rural aerosol characterization of summer smog events during the PIPAPO field campaign in Milan, Italy

    NASA Astrophysics Data System (ADS)

    Baltensperger, U.; Streit, N.; Weingartner, E.; Nyeki, S.; PréVôT, A. S. H.; van Dingenen, R.; Virkkula, A.; Putaud, J.-P.; Even, A.; ten Brink, H.; Blatter, A.; Neftel, A.; GäGgeler, H. W.

    2002-11-01

    A comprehensive range of aerosol parameters was measured at an urban and a rural site in the Milan, Italy metropolitan region during summer smog events in summer 1998. Measurements were performed as part of the Pianura Padana Produzione di Ozono (PIPAPO) field campaign to determine the sensitivity of O3 production to NOX and volatile organic carbon concentrations at several ground stations. Primary aerosol parameters (i.e., direct emissions) such as aerosol black carbon showed a distinct diurnal variation with maxima at about 0000 and 0800 central European summer time (CEST), in contrast to secondary aerosol parameters such as sulfate and nitrate. Aerosol number size distributions were measured under ambient conditions as well as after conditioning with volatility and hygroscopicity systems. A mode at d = 20-30 nm in the number concentration was found at 0800 CEST and exhibited high volatility at 110°C (˜80% volume lost upon heating) but no hygroscopic behavior. Based on these measurements, small particles (d < 40 nm) are thought to consist mainly of hydrophobic particulate organic matter, rather than soot or H2SO4 aerosols. Two distinct hygroscopic modes with average growth factors d/d0 ˜ 1.02 and 1.21-1.28 were found for particles with dry (relative humidity of <30%) diameters d0 = 50-200 nm. Submicrometer aerosols exhibited lower volatility at the rural than at the urban site, which is attributed to additional particulate mass produced by secondary particle formation.

  10. Urban and rural aerosol characterization of summer smog events during the PIPAPO field campaign in Milan, Italy

    NASA Astrophysics Data System (ADS)

    Baltensperger, U.; Streit, N.; Weingartner, E.; Nyeki, S.; Prévôt, A. S. H.; Van Dingenen, R.; Virkkula, A.; Putaud, J.-P.; Even, A.; ten Brink, H.; Blatter, A.; Neftel, A.; Gäggeler, H. W.

    2002-10-01

    A comprehensive range of aerosol parameters was measured at an urban and a rural site in the Milan, Italy metropolitan region during summer smog events in summer 1998. Measurements were performed as part of the Pianura Padana Produzione di Ozono (PIPAPO) field campaign to determine the sensitivity of O3 production to NOX and volatile organic carbon concentrations at several ground stations. Primary aerosol parameters (i.e., direct emissions) such as aerosol black carbon showed a distinct diurnal variation with maxima at about 0000 and 0800 central European summer time (CEST), in contrast to secondary aerosol parameters such as sulfate and nitrate. Aerosol number size distributions were measured under ambient conditions as well as after conditioning with volatility and hygroscopicity systems. A mode at d = 20-30 nm in the number concentration was found at 0800 CEST and exhibited high volatility at 110°C (~80% volume lost upon heating) but no hygroscopic behavior. Based on these measurements, small particles (d < 40 nm) are thought to consist mainly of hydrophobic particulate organic matter, rather than soot or H2SO4 aerosols. Two distinct hygroscopic modes with average growth factors d/d0 ~ 1.02 and 1.21-1.28 were found for particles with dry (relative humidity of <30%) diameters d0 = 50-200 nm. Submicrometer aerosols exhibited lower volatility at the rural than at the urban site, which is attributed to additional particulate mass produced by secondary particle formation.

  11. Performance of Combination Drug and Hygroscopic Excipient Submicrometer Particles from a Softmist Inhaler in a Characteristic Model of the Airways

    PubMed Central

    Longest, P. Worth; Tian, Geng; Li, Xiang; Son, Yoen-Ju; Hindle, Michael

    2012-01-01

    Excipient enhanced growth (EEG) of inhaled submicrometer pharmaceutical aerosols is a recently proposed method intended to significantly reduce extrathoracic deposition and improve lung delivery. The objective of this study was to evaluate the size increase of combination drug and hygroscopic excipient particles in a characteristic model of the airways during inhalation using both in vitro experiments and CFD simulations. The airway model included a characteristic mouth-throat (MT) and upper tracheobronchial (TB) region through the third bifurcation (B3) and was enclosed in a chamber geometry used to simulate the thermodynamic conditions of the lungs. Both in vitro results and CFD simulations were in close agreement and indicated that EEG delivery of combination submicrometer particles could nearly eliminate MT deposition for inhaled pharmaceutical aerosols. Compared with current inhalers, the proposed delivery approach represents a 1–2 order of magnitude reduction in MT deposition. Transient inhalation was found to influence the final size of the aerosol based on changes in residence times and relative humidity values. Aerosol sizes following EEG when exiting the chamber (2.75–4.61 μm) for all cases of initial submicrometer combination particles were equivalent to or larger than many conventional pharmaceutical aerosols that frequently have MMADs in the range of 2–3 μm. PMID:22820981

  12. AEROSOL GROWTH IN A STEADY-STATE, CONTINUOUS FLOW CHAMBER: APPLICATION TO STUDIES OF SECONDARY AEROSOL FORMATION

    EPA Science Inventory

    An analytical solution for the steady-state aerosol size distribution achieved in a steady-state, continuous flow chamber is derived, where particle growth is occurring by gas-to-particle conversion and particle loss is occurring by deposition to the walls of the chamber. The s...

  13. Study of the effect of humidity, particle hygroscopicity and size on the mass loading capacity of HEPA filters

    SciTech Connect

    Gupta, A.

    1992-01-01

    The effect of humidity, particle hygroscopicity and size on the mass loading capacity of glass fiber HEPA filters has been studied. At humidifies above the deliquescent point, the pressure drop across the HEPA filter increased non-linearly with the areal loading density (mass collected/filtration area) of NaCl aerosol, thus significantly reducing the mass loading capacity of the filter compared to dry hygroscopic or non-hygroscopic particle mass loadings. The specific cake resistance, K{sub 2}, has been computed for different test conditions and used as a measure of the mass loading capacity. K. was found to decrease with increasing humidity for the non-hygroscopic aluminum oxide particles and the hygroscopic NaCl particles (at humidities below the deliquescent point). It is postulated that an increase in humidity leads to the formation of a more open particulate cake which lowers the pressure drop for a given mass loading. A formula for predicting K{sub 2} for lognormally distributed aerosols (parameters obtained from impactor data) is derived. The resistance factor, R, calculated using this formula was compared to the theoretical R calculated using the Rudnick-Happel expression. For the non-hygroscopic aluminum oxide the agreement was good but for the hygroscopic sodium chloride, due to large variation in the cake porosity estimates, the agreement was poor.

  14. Study of the effect of humidity, particle hygroscopicity and size on the mass loading capacity of HEPA filters

    SciTech Connect

    Gupta, A.

    1992-09-01

    The effect of humidity, particle hygroscopicity and size on the mass loading capacity of glass fiber HEPA filters has been studied. At humidifies above the deliquescent point, the pressure drop across the HEPA filter increased non-linearly with the areal loading density (mass collected/filtration area) of NaCl aerosol, thus significantly reducing the mass loading capacity of the filter compared to dry hygroscopic or non-hygroscopic particle mass loadings. The specific cake resistance, K{sub 2}, has been computed for different test conditions and used as a measure of the mass loading capacity. K. was found to decrease with increasing humidity for the non-hygroscopic aluminum oxide particles and the hygroscopic NaCl particles (at humidities below the deliquescent point). It is postulated that an increase in humidity leads to the formation of a more open particulate cake which lowers the pressure drop for a given mass loading. A formula for predicting K{sub 2} for lognormally distributed aerosols (parameters obtained from impactor data) is derived. The resistance factor, R, calculated using this formula was compared to the theoretical R calculated using the Rudnick-Happel expression. For the non-hygroscopic aluminum oxide the agreement was good but for the hygroscopic sodium chloride, due to large variation in the cake porosity estimates, the agreement was poor.

  15. DEPOSITION OF SULFATE ACID AEROSOLS IN THE DEVELOPING HUMAN LUNG

    EPA Science Inventory

    Computations of aerosol deposition as affected by (i) aerosol hygroscopicity, (ii) human age, and (iii) respiratory intensity are accomplished using a validated mathematical model. he interactive effects are very complicated but systematic. ew general observations can be made; ra...

  16. Nonequilibrium Atmospheric Secondary Organic Aerosol Formation and Growth

    SciTech Connect

    Perraud, Veronique M.; Bruns, Emily A.; Ezell, Michael J.; Johnson, Stanley N.; Yu, Yong; Alexander, M. L.; Zelenyuk, Alla; Imre, D.; Chang, W. L.; Dabdub, Donald; Pankow, James F.; Finlayson-Pitts, Barbara J.

    2012-02-21

    Airborne particles play a critical role in air quality, human health effects, visibility and climate. Secondary organic aerosols (SOA) account for a significant portion of total airborne particles. They are formed in reactions of organic gases that produce low volatility and semi-volatile organic compounds (SVOCs). Current atmospheric models assume that SOA are liquids into which SVOCs undergo equilibrium partitioning and grow the particles. However a large discrepancy between model predictions and field measurements of SOA is commonly observed. We report here laboratory studies of the oxidation of a-pinene by ozone and nitrate radicals and show that particle composition is actually consistent with a kinetically determined growth mechanism, and not with equilibrium partitioning between the gas phase and liquid particles. If this is indeed a general phenomenon in air, the formulation of atmospheric SOA models will have to be revised to reflect this new paradigm. This will have significant impacts on quantifying the role of SOA in air quality, visibility, and climate.

  17. The single scattering properties of hygroscopic soot aggregates with water coated monomers

    NASA Astrophysics Data System (ADS)

    YU, W.; Tianhai, C.; Hao, C.; Lijuan, Z.

    2013-12-01

    Anthropogenic aerosols, such as soot, have modified the Earth's radiation balance by scattering and absorbing solar and long-wave radiative transmission, which have largely influenced the global climate change since the industrial era. Based on transmission electron microscope images (TEM), soot particles are shown as the complex, fractal-like aggregate structures. In humid atmospheric environments, these soot aggregates tend to acquire a water coating, which introduces further complexity to the problem of determining the optical properties of the aggregates. The hygroscopic growth of soot aggregates is important for the aging of these absorbing aerosols, which can significantly influence the optical properties of these kinds of soot particles. In this paper, according to the specific volume fractions of soot core in the water coated soot particle, the monomers of fractal soot aggregates are modeled as semi-external mixtures (physical contact) with constant radius of soot core and variable size of water coating. The single scattering properties of these hygroscopic soot particles, such as phase function, the cross sections of extinction, absorption and scatting, single scattering albedo (SSA), and asymmetry parameter (ASY), are calculated using the numerically exact superposition T-matrix method. The morphological effects are compared with different monomer numbers and fractal dimension of the soot aggregates, as well as different size of water coating for these spherical monomers. The results have shown that the extinction and absorption cross sections are decreased for the soot aggregates with more thick water coating on monomers, but the single scattering albedo is increased for the larger water coating. It is found that the SSA of aged soot aggregates with hygroscopic grown are remarkably (~50% for volume fraction of soot aggregates is 0.5) larger than fresh soot particles without the consideration of water coating, due to the size of water coating and the

  18. Results and recommendations from an intercomparison of six Hygroscopicity-TDMA systems

    NASA Astrophysics Data System (ADS)

    Massling, A.; Niedermaier, N.; Hennig, T.; Fors, E.; Swietlicki, E.; Ehn, M.; Hämeri, K.; Villani, P.; Laj, P.; Good, N.; McFiggans, G.; Wiedensohler, A.

    2010-02-01

    The performance of six custom-built Hygrocopicity-Tandem Differential Mobility Analyzers (H-TDMA) systems was investigated in the frame of an international calibration and intercomparison workshop held in Leipzig, February 2006. The goal of the workshop was to harmonize H-TDMA measurements and develop recommendations for atmospheric measurements and their data evaluation. The H-TDMA systems were compared in terms of the sizing of dry particles, relative humidity (RH) uncertainty and consistency in determination of number fractions of different hygroscopic particle groups. The experiments were performed in an air-conditioned laboratory using ammonium sulfate particles or an external mixture of ammonium sulfate and soot particles. The sizing of dry particles of the six H-TDMA systems was within 0.2 to 4.2% of the selected particle diameter depending on investigated size and individual system. With regard to RH uncertainties, the H-TDMA systems showed deviations up to 4.5% RH from the set point at RH=90% investigating the hygroscopic growth of ammonium sulfate particles and comparing the results with theory. The evaluation of number fractions investigating an externally mixed aerosol delivered differences up to +/-8% in calculated number fraction for one and the same aerosol type. We analysed the datasets of the different H-TDMAs with one fitting routine to investigate differences caused by the different data evaluation procedures. The results showed that the differences were reduced from +12/-13% to +8/-6%. We can conclude here that a common data evaluation procedure to determine the number fraction of externally mixed aerosols will improve the comparability of H-TDMA measurements. We finally recommend, to ensure a good calibration of all flow, temperature and RH sensors in the systems. It is most important to thermally insulate the RH control unit and the second DMA and to monitor those temperatures as accurately as 0.2 °C. For a correct determination of external

  19. Effect of growth media and washing on the spectral signatures of aerosolized biological simulants.

    PubMed

    Laflamme, Christian; Simard, Jean-Robert; Buteau, Sylvie; Lahaie, Pierre; Nadeau, Denis; Déry, Bernard; Houle, Olivier; Mathieu, Pierre; Roy, Gilles; Ho, Jim; Duchaine, Caroline

    2011-02-20

    We have evaluated the influence of growth media and washing on the laser-induced fluorescence spectra of bacteria. Three different bacterial simulants were cultured in three types of growth media. Three kinds of samples were generated from each culture: the culture itself, the growth medium alone, and a triple-washed sample. The materials were injected as aerosols in a lab-sized lidar aerosol chamber to obtain their spectra. Using two different analysis approaches, signature variations were observed between the three kinds of samples for most combinations of growth media/bacteria. This study concludes that the culture media used influences the spectral signatures. PMID:21343956

  20. Secondary Organic Aerosol Formation in the Captive Aerosol Growth and Evolution (CAGE) Chambers during the Southern Oxidant and Aerosol Study (SOAS) in Centreville, AL

    NASA Astrophysics Data System (ADS)

    Leong, Y.; Karakurt Cevik, B.; Hernandez, C.; Griffin, R. J.; Taylor, N.; Matus, J.; Collins, D. R.

    2013-12-01

    Secondary organic aerosol (SOA) represents a large portion of sub-micron particulate matter on a global scale. The composition of SOA and its formation processes are heavily influenced by anthropogenic and biogenic activity. Volatile organic compounds (VOCs) that are emitted naturally from forests or from human activity serve as precursors to SOA formation. Biogenic SOA (BSOA) is formed from biogenic VOCs and is prevalent in forested regions like the Southeastern United States. The formation and enhancement of BSOA under anthropogenic influences such as nitrogen oxides (NOx), sulfur dioxide (SO2), and oxygen radicals are still not well understood. The lack of information on anthropogenic BSOA enhancement and the reversibility of SOA formation could explain the underprediction of SOA in current models. To address some of these gaps in knowledge, this study was conducted as part of the Southern Oxidant and Aerosol Study (SOAS) in Centreville, AL during the summer of 2013. SOA growth experiments were conducted in two Captive Aerosol Growth and Evolution (CAGE) outdoor chambers located at the SEARCH site. Ambient trace gas concentrations were maintained in these chambers using semi-permeable gas-exchange membranes, while studying the growth of injected monodisperse seed aerosol. The control chamber was operated under ambient conditions; the relative humidity and oxidant and NOx levels were perturbed in the second chamber. This design allows experiments to capture the natural BSOA formation processes in the southeastern atmosphere and to study the influence of anthropogenic activity on aerosol chemistry. Chamber experiments were periodically monitored with physical and chemical instrumentation including a scanning mobility particle sizer (SMPS), a cloud condensation nuclei counter (CCNC), a humidified tandem differential mobility analyzer (H-TDMA), and an Aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS). The CAGE experiments focused on SOA

  1. On the Water Uptake and CCN Activation of Tropospheric Organic Aerosols

    NASA Astrophysics Data System (ADS)

    Rastak, Narges; Pajunoja, Aki; Acosta Navarro, Juan-Camilo; Leong, Yu Jun; Cerully, Kate M.; Nenes, Athanasios; Kirkevåg, Alf; Topping, David; Virtanen, Annele; Riipinen, Ilona

    2016-04-01

    Aerosol particles introduce high uncertainties to radiative climate forcing. If exposed to a given relative humidity (RH), aerosol particles containing soluble material can absorb water and grow in size (hygroscopic growth). If RH is increased further beyond supersaturation (RH >100%) the particles can act as cloud condensation nuclei (CCN). Aerosol particles interactions with water vapour determine to a large extent their influence on climate. Organic aerosols (OA) contribute a large fraction (20-90%) of atmospheric submicron particulate mass, on the other hand they often consist of thousands of compounds with different properties. One of these properties is solubility, which affects the hygroscopic growth and cloud condensation nucleus (CCN) activation of the organic particles. We investigate the hygroscopic behaviour of complex organic aerosols accounting for the distribution of solubilities present in these mixtures. We use the SPARC method to estimate the solubility distributions of isoprene (IP) and monoterpene (MT) SOA based on their chemical composition, as predicted by the Master Chemical Mechanism (MCM). Combining these solubility distributions with the adsorption theory along with the non-ideal behaviour of organic mixtures, we predict the expected hygroscopic growth factors (HGFs), CCN activation behaviour and the related hygroscopicity parameters kappa for these mixtures. The predictions are compared to laboratory measurements as well as field data from MT- and IP-dominated measurement sites. The predicted solubility distributions do a good job in explaining the water uptake of these two mixture types at high relative humidities (RH around 90%), as well as their CCN activation - including the potential differences between the kappa values derived from HGF vs. CCN data. At lower relative humidities, however, the observed water uptake is higher than predicted on solubility alone, particularly for the MT-derived SOA. The data from the low RHs are further

  2. Condensational growth and trace species scavenging in stratospheric sulfuric acid/water aerosol droplets

    NASA Technical Reports Server (NTRS)

    Tompson, Robert V., Jr.

    1991-01-01

    Stratospheric aerosols play a significant role in the environment. The composition of aerosols is believed to be a liquid solution of sulfuric acid and water with numerous trace species. Of these trace species, ozone in particular was recognized as being very important in its role of shielding the environment from harmful ultraviolet radiation. Also among the trace species are HCl and ClONO2, the so called chlorine reservoir species and various oxides of nitrogen. The quantity of stratospheric aerosol and its particle size distribution determines, to a large degree, the chemistry present in the stratosphere. Aerosols experience 3 types of growth: nucleation, condensation, and coagulation. The application of condensation investigations to the specific problem of stratospheric aerosols is discussed.

  3. 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

  4. Condensational Growth of Combination Drug-Excipient Submicrometer Particles for Targeted High Efficiency Pulmonary Delivery: Comparison of CFD Predictions with Experimental Results

    PubMed Central

    Hindle, Michael

    2011-01-01

    Purpose The objective of this study was to investigate the hygroscopic growth of combination drug and excipient submicrometer aerosols for respiratory drug delivery using in vitro experiments and a newly developed computational fluid dynamics (CFD) model. Methods Submicrometer combination drug and excipient particles were generated experimentally using both the capillary aerosol generator and the Respimat inhaler. Aerosol hygroscopic growth was evaluated in vitro and with CFD in a coiled tube geometry designed to provide residence times and thermodynamic conditions consistent with the airways. Results The in vitro results and CFD predictions both indicated that the initially submicrometer particles increased in mean size to a range of 1.6–2.5 µm for the 50:50 combination of a non-hygroscopic drug (budesonide) and different hygroscopic excipients. CFD results matched the in vitro predictions to within 10% and highlighted gradual and steady size increase of the droplets, which will be effective for minimizing extrathoracic deposition and producing deposition deep within the respiratory tract. Conclusions Enhanced excipient growth (EEG) appears to provide an effective technique to increase pharmaceutical aerosol size, and the developed CFD model will provide a powerful design tool for optimizing this technique to produce high efficiency pulmonary delivery. PMID:21948458

  5. Variability of CCN Activation Behaviour of Aerosol Particles in the Marine Boundary Layer of the Northern and Southern Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Henning, Silvia; Dieckmann, Katrin; Hartmann, Susan; Schäfer, Michael; Wu, Zhijun; Merkel, Maik; Wiedensohler, Alfred; Stratmann, Frank

    2013-04-01

    The variability of cloud condensation nucleus (CCN) activation behaviour and total CCN number concentrations was investigated during three ship cruises. Measurements were performed in a mobile laboratory on the German research vessel FS Polarstern cruising between Cape Town and Bremerhaven (April / May and October / November 2011) as well as between Punta Arenas and Bremerhaven (April / May 2012). CCN size distributions were measured for supersaturations between 0.1% and 0.4% using a Cloud Condensation Nucleus Counter (DMT, USA). Aerosol particle and CCN total number concentrations as well as the hygroscopicity parameter κ (Petters and Kreidenweis, 2007) were determined. Furthermore, size distribution data were collected. The hygroscopicity parameter κ featured a high variability during the cruises, with a median κ-value of 0.52 ± 0.26. The κ-values are depended on air mass origin; and are as expected mainly dominated by marine influences, but also long range transport of aerosol particles was detected. In the Celtic Sea, κ was found to be lower than that of clean marine aerosol particles (0.72 ± 0.24; Pringle et al., 2010) with κ-values ~0.2, possibly influenced by anthropogenic emissions from Europe. Close to the West African coast particle hygroscopicity was found to be influenced by the Saharan dust plume, resulting in low κ-values ~0.25. Petters, M.D. and S.M. Kreidenweis (2007), A single parameter representation of hygroscopic growth and cloud condensation nucleus activity, Atmos. Chem. and Phys., 7, 1961-1971. Pringle, K.J., H. Tost, A. Pozzer, U. Pöschl, and J. Lelieveld (2010), Global distribution of the effective aerosol hygroscopicity parameter for CCN activation, Atmos. Chem. Phys., 10, 5241-5255.

  6. Hygroscopicity Evaluation of Halide Scintillators

    SciTech Connect

    Zhuravleva, M; Stand, L; Wei, H; Hobbs, C. L.; Boatner, Lynn A; Ramey, Joanne Oxendine; Burger, Arnold; Rowe, E; Bhattacharya, P.; Tupitsyn, E; Melcher, Charles L

    2014-01-01

    A collaborative study of relative hygroscopicity of anhydrous halide scintillators grown at various laboratories is presented. We have developed a technique to evaluate moisture sensitivity of both raw materials and grown crystals, in which the moisture absorption rate is measured using a gravimetric analysis. Degradation of the scintillation performance was investigated by recording gamma-ray spectra and monitoring the photopeak position, count rate and energy resolution. The accompanying physical degradation of the samples exposed to ambient atmosphere was photographically recorded as well. The results were compared with ben

  7. What Can We Learn From Laboratory Studies of Inorganic Sea Spray Aerosol?

    NASA Astrophysics Data System (ADS)

    Salter, M. E.; Zieger, P.; Acosta Navarro, J. C.; Grythe, H.; Kirkevag, A.; Rosati, B.; Riipinen, I.; Nilsson, E. D.

    2015-12-01

    Since 2013 we have been operating a temperature-controlled plunging-jet sea spray aerosol chamber at Stockholm University using inorganic artificial seawater. Using size-resolved measurements of the foam bubbles responsible for the aerosol production we were able to show that it is changes to these foam bubbles which drive the observed changes in aerosol production and size distribution as water temperature changes (Salter et al., 2014). Further, by combining size-resolved measurements of aerosol production as a function of water temperature with measurements of air entrainment by the plunging-jet we have developed a temperature-dependent sea spray source function for deployment in large-scale models (Salter et al., 2015). We have also studied the hygroscopicity, morphology, and chemical composition of the inorganic sea spray aerosol produced in the chamber. The sea spray aerosol generated from artificial seawater exhibited lower hygroscopic growth than both pure NaCl and output from the E-AIM aerosol thermodynamics model when all relevant inorganic ions in the sea salt were included. Results from sensitivity tests using a large-scale earth system model suggest that the lower hygroscopicity observed in our laboratory measurements has important implications for calculations of the radiative balance of the Earth. In addition, size-dependent chemical fractionation of several inorganic ions was observed relative to the artificial seawater with potentially important implications for the chemistry of the marine boundary layer. Each of these studies suggest that there is still much to be learned from rigorous experiments using inorganic seawater proxies. Salter et al., (2014), On the seawater temperature dependence of the sea spray aerosol generated by a continuous plunging jet. J. Geophys. Res. Atmos., 119, 9052-9072, doi: 10.1002/2013JD021376 Salter et al., (2015), An empirically derived inorganic sea spray source function incorporating sea surface temperature. Atmos

  8. GROWTH LAWS FOR THE FORMATION OF SECONDARY AMBIENT AEROSOLS: IMPLICATIONS FOR CHEMICAL CONVERSION MECHANISMS

    EPA Science Inventory

    The evolution of aerosol size distributions growing by gas-to-particle conversion has been observed recently in field and laboratory studies. A technique for extracting particle diameter growth rates from such data is presented. The functional dependence of these growth rates on ...

  9. Tracking sources of severe haze episodes and their physicochemical and hygroscopic properties under Asian continental outflow: Long-range transport pollution, postharvest biomass burning, and Asian dust

    NASA Astrophysics Data System (ADS)

    Jung, Jinsang; Kim, Young J.

    2011-01-01

    Aerosol physicochemical and hygroscopic properties were measured from 12 October to 21 November 2005 at a downwind area of the Asian continental outflow (Gwangju, Korea) to characterize severe haze episodes. Using optically measured elemental carbon (EC) at 660 nm (Opt.EC) and 880 nm (BC) wavelengths and Mie theory, it was estimated that the higher BC/Opt.EC ratio during the cloudy day of the long-range transport (LTP) period was mainly due to EC particle growth from in-cloud processing with secondary aerosols such as sulfate and organic aerosols. Single scattering albedo (SSA) of biomass burning (BB) aerosol increased sharply from 0.89 to 0.94 under a relative humidity >70%, suggesting that organic aerosols emitted from rice straw burning contained high amounts of hydrophilic compounds. The contribution of aerosol water content to the total light extinction coefficient (bext) was determined as 51.4% and 68.4% during the BB and BB + LTP periods, respectively, indicating that the haze episodes were highly enhanced by an increase in aerosol water content. The Asian dust event was characterized by the highest SSA (0.92 ± 0.02), the lowest mass scattering efficiency of fine particles (2.5 ± 1.0 m2 g-1), and the lowest hygroscopic nature (humidity-dependent light scattering enhancement factor, f(80%), which is defined by the ratio of light scattering coefficient at 80% relative humidity to that at dry condition, = ˜1.37). Based on the Ångström exponent (α) values observed at the source region of the Asian continent and the downwind area of South Korea during the BB + LTP period, it was found that the α value of urban aerosols decreased ˜11% for 1-2 days of the transport, probably due to the increase in particle size through water uptake. Increasing rates of surface PM10 mass concentrations at western coastal areas of the South Korean peninsula were in the range 2.4-14.4 μgm-3 h-1 at the beginning of the BB + LTP period (24 October 2005, 0700-2300 LT). Based on

  10. The effects of hygroscopicity of fossil fuel BC on mixed-phase and cirrus ice clouds

    NASA Astrophysics Data System (ADS)

    Yun, Y.; Penner, J. E.

    2010-12-01

    Fossil fuel burning BC aerosols are often emitted together with sulfate, which coats the surface of these BC particles and changes their hygroscopicity. The ice forming capability of the fossil fuel burning BC can differ widely as a result of the amount of soluble coating on their surface. Due to the abundance of fossil fuel burning BC particles, a small change in their activated fraction can produce a large difference in their climate forcing. To better quantify the role of fossil fuel burning BC in climate change, a 3-BC (hydrophobic, hydrophilic and hygroscopic BC) scheme is developed to replace the 1-BC scheme in a coupled climate and aerosol transport model (CAM-IMPACT). The new scheme explicitly calculates the condensation and coagulation of sulfate on BC particles and keeps track of their coating in the 3-BC states. The hygroscopicity of BC is determined by the layers of sulfate coating on their surface according to criteria developed in laboratory observations. The ice formation scheme in mixed-phase and cirrus clouds is also updated to treat the 3 hygroscopicity BC groups separately according to their different ice freezing capabilities. This paper will report the climate forcing associated with the new BC scheme as well as comparison with observations.

  11. 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

  12. Size-resolved aerosol water uptake and cloud condensation nuclei measurements as measured above a Southeast Asian rainforest during OP3

    NASA Astrophysics Data System (ADS)

    Irwin, M.; Robinson, N.; Allan, J. D.; Coe, H.; McFiggans, G.

    2011-11-01

    The influence of the properties of fine particles on the formation of clouds and precipitation in the tropical atmosphere is of primary importance to their impacts on radiative forcing and the hydrological cycle. Measurements of aerosol number size distribution, hygroscopicity in both sub- and supersaturated regimes and composition were taken between March and July 2008 in the tropical rainforest in Borneo, Malaysia, marking the first study of this type in an Asian tropical rainforest. Hygroscopic growth factors (GF) at 90 % relative humidity (RH) for the dry diameter range D0 = 32-258 nm, supersaturated water uptake behaviour for the dry diameter range D0 = 45-300 nm and aerosol chemical composition were simultaneously measured using a Hygroscopicity Tandem Differential Mobility Analyser (HTDMA), a Droplet Measurement Technologies Cloud Condensation Nuclei counter (CCNc) and an Aerodyne Aerosol Mass Spectrometer (AMS) respectively. The hygroscopicity parameter κ was derived from both CCNc and HTDMA measurements, with the resulting values of κ ranging from 0.05-0.37, and 0.17-0.37, respectively. Although the total range of κ values is in good agreement, there are inconsistencies between CCNc and HTDMA derived κ values at different dry diameters. Results from a study with similar methodology performed in the Amazon rainforest report values for κ within a similar range to those reported in this work, indicating that the aerosol as measured from both sites shows similar hygroscopic properties. However, the derived number of cloud condensation nuclei (NCCN) were much higher in the present experiment than the Amazon, resulting in part from the increased total particle number concentrations observed in the Bornean rainforest. This contrast between the two environments may be of substantial importance in describing the impacts of particles in the tropical atmosphere.

  13. Computation of ammonium bisulfate aerosol deposition in conducting airways

    SciTech Connect

    Martonen, T.B.; Patel, M.

    1981-11-01

    Experimental measurements of the growth of monodisperse dry NH/sub 4/HSO/sub 4/ aerosols by H/sub 2/O vapor condensation have been reported in the literature. These data are incorporated into an aerosol deposition model to study the behavior of inhaled NH/sub 4/HSO/sub 4/ particles, which is of concern in relation to human health. The tracheobronchial tree is described by Weibel's model A morphology, and Landahl's formulas are used to compute particle deposition efficiencies. Enhanced losses in the trachea due to the action of the laryngeal jet are accounted for by using an empirical deposition efficiency equation. The effect of NH/sub 4/HSO/sub 4/ aerosol growth is quantitated by comparisons of total and intrabronchial deposition probabilities with those of a nonhygroscopic aerosol of equal aerodynamic size. Computations indicate that hygroscopic growth effects are a function of the size of the particles inhaled. Total deposition efficiencies of NH/sub 4/HSO/sub 4/-H/sub 2/O droplet aerosols are greater than those of nonhygroscopic aerosols only if the former originate from dry NH/sub 4/HSO/sub 4/ particles exceeding a critical geometric diameter of 0.3 ..mu..m. Growth effects are explained in terms of the relative efficiencies of the dominant deposition mechanisms active in the lung.

  14. Influence of functional groups on organic aerosol cloud condensation nucleus activity.

    PubMed

    Suda, Sarah R; Petters, Markus D; Yeh, Geoffrey K; Strollo, Christen; Matsunaga, Aiko; Faulhaber, Annelise; Ziemann, Paul J; Prenni, Anthony J; Carrico, Christian M; Sullivan, Ryan C; Kreidenweis, Sonia M

    2014-09-01

    Organic aerosols in the atmosphere are composed of a wide variety of species, reflecting the multitude of sources and growth processes of these particles. Especially challenging is predicting how these particles act as cloud condensation nuclei (CCN). Previous studies have characterized the CCN efficiency for organic compounds in terms of a hygroscopicity parameter, κ. Here we extend these studies by systematically testing the influence of the number and location of molecular functional groups on the hygroscopicity of organic aerosols. Organic compounds synthesized via gas-phase and liquid-phase reactions were characterized by high-performance liquid chromatography coupled with scanning flow CCN analysis and thermal desorption particle beam mass spectrometry. These experiments quantified changes in κ with the addition of one or more functional groups to otherwise similar molecules. The increase in κ per group decreased in the following order: hydroxyl ≫ carboxyl > hydroperoxide > nitrate ≫ methylene (where nitrate and methylene produced negative effects, and hydroperoxide and nitrate groups produced the smallest absolute effects). Our results contribute to a mechanistic understanding of chemical aging and will help guide input and parametrization choices in models relying on simplified treatments such as the atomic oxygen:carbon ratio to predict the evolution of organic aerosol hygroscopicity. PMID:25118824

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

    SciTech Connect

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

    1994-12-31

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

  16. FUNDAMENTAL STUDY OF SULFATE AEROSOL FORMATION, CONDENSATION, AND GROWTH

    EPA Science Inventory

    The report gives results of a study of the formation and growth of sulfate particles. Existing theoretical models on acid particle formation and growth were reviewed and evaluated. The formation and growth of sulfate particles during slow cooling, rapid cooling, and dilution cool...

  17. Modeling aerosol growth by aqueous chemistry in nonprecipitating stratiform cloud

    SciTech Connect

    Ovchinnikov, Mikhail; Easter, Richard C.

    2010-07-29

    A new microphysics module based on a two-dimensional (2D) joint size distribution function representing both interstitial and cloud particles is developed and applied to studying aerosol processing in non-precipitating stratocumulus clouds. The module is implemented in a three-dimensional dynamical framework of a large-eddy simulation (LES) model and in a trajectory ensemble model (TEM). Both models are used to study the modification of sulfate aerosol by the activation - aqueous chemistry - resuspension cycle in shallow marine stratocumulus clouds. The effect of particle mixing and different size-distribution representations on modeled aerosol processing are studied in a comparison of the LES and TEM simulations with the identical microphysics treatment exposes and a comparison of TEM simulations with a 2D fixed and moving bin microphysics. Particle mixing which is represented in LES and neglected in the TEM leads to the mean relative per particle dry mass change in the TEM simulations being about 30% lower than in analogous subsample of LES domain. Particles in the final LES spectrum are mixed in from different “parcels”, some of which have experienced longer in-cloud residence times than the TEM parcels, all of which originated in the subcloud layer, have. The mean relative per particle dry mass change differs by 14% between TEM simulations with fixed and moving bin microphysics. Finally, the TEM model with the moving bin microphysics is used to evaluate assumptions about liquid water mass partitioning among activated cloud condensation nuclei (CCN) of different dry sizes. These assumptions are used in large-scale models to map the bulk aqueous chemistry sulfate production, which is largely proportional to the liquid water mass, to the changes in aerosol size distribution. It is shown that the commonly used assumptions that the droplet mass is independent of CCN size or that the droplet mass is proportional to the CCN size to the third power do not perform

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

    NASA Astrophysics Data System (ADS)

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

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

  19. 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.

  20. Measurements of physical and chemical properties of urban aerosols and their CCN activities in Seoul during the KORUS-AQ pre-campaign

    NASA Astrophysics Data System (ADS)

    Kim, N.; Yum, S. S.; Park, M.; Shin, H. J.; Bae, G. N.; Kwak, K. H.; Park, J. S.; Park, S. M.; Ahn, J.

    2015-12-01

    Interest in cloud condensation nuclei (CCN) has been increasing for the last few decades due to their first order effects on radiative and microphysical properties of clouds. Particularly, scientific understanding of CCN from anthropogenic sources becomes important because it is now considered that large uncertainties in climate change predictions stem from insufficient understanding of CCN. CCN activity is influenced by size and chemical component of aerosols. The KORUS-AQ campaign, jointly organized by National Institute of Environmental Research (NIER) of Korea and National Aeronautics and Space Administration (NASA) aims at understanding various aspects of air quality problem in Korea and will be held in spring, 2016. In preparation for this campaign, pre-campaign was held during May 18-June 13, 2015, in Seoul where numerous local anthropogenic sources exist and influence of Chinese continental outflow directly affects. Here we present some of the important results from the pre-campaign. Chemical properties of aerosols were measured with AMS. Aerosol and CCN number concentrations, aerosol size distribution and aerosol hygroscopic growth factor were measured by CPC, CCN counter, SMPS and H-TDMA, respectively. Average diurnal variation of aerosol number concentration showed three dominant peaks at around 0600_UTC and morning and evening rush hours. Each peak seemed to have different characteristics and therefore detailed analyses of physical and chemical properties of aerosols during the peaks as well as during some special events will be made. The hygroscopicity parameter, kappa, will be estimated by examining CCN activity, H-TDMA measured hygroscopic growth factor and mixing rule of aerosol chemical components, and the result will be compared as well.

  1. Estimating aerosol light scattering at the Fresno Supersite

    NASA Astrophysics Data System (ADS)

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

    Aerosol light scattering (Bsp) was estimated from particle size and chemical measurements during the winter intensive period (15 December 2000-3 February 2001) at the Fresno Supersite as part of the California Regional PM 10/PM 2.5 Air Quality Study (CRPAQS). Bsp was underestimated by 41-46% from scanning mobility particle sizer (SMPS) and optical particle counter (OPC) particle size distributions depending on assumptions about refractive index and hygroscopic growth. Bsp was underestimated by 35% using the Interagency Monitoring of PROtected Visual Environments (IMPROVE) light extinction equation and by 25% using chemical size distributions measured with micro orifice uniform deposit impactor (MOUDI) cascade impactors and a Desert Research Institute (DRI) PM 2.5 sequential filter sampler (SFS). Underestimation of Bsp in Fresno was related to differences in the temperature and relative humidity (RH) at which various measurements were made. Evaporation of ammonium nitrate in the heated environment in which the SMPS and OPC instruments were located caused a reduction in particle size and number concentration. The MOUDI was operated outdoors at ambient temperature and RH, while a smart-heater equipped Radiance nephelometer was operated at RH <72%. Comparing estimated and measured Bsp required adjusting the SMPS, OPC, and MOUDI size distributions to the nephelometer RH. A systematic low-bias in estimated scattering suggests that organic aerosols may have contributed to hygroscopic growth. Consistent measurement strategies are needed to properly estimate aerosol light extinction under conditions such as those found in Fresno during winter.

  2. Influence Of Relative Humidity On Light Scattering Measurements Of Aerosols Using A Humidifier-Dryer Nephelometer

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

    Atmospheric aerosols influence the Earth's radiation budget both directly and indirectly. In the direct effect, aerosols scatter and absorb sunlight changing the radiative balance of the Earth-atmosphere system. Aerosols indirectly influence the Earth's radiation budget by modifying the microphysical and radiative properties, as well as the water content and lifetime of clouds. In atmosphere conditions, aerosol particles experience hygroscopic growth due to the relative humidity (RH) influence. Wet aerosols particles are larger than their dry equivalents, therefore they scatter more light. Quantitative knowledge of the RH effect and its influence on the light scattering coefficient on aerosol particles is of substantial importance when comparing ground based observation with other optical aerosol measurements techniques such satellite retrieval and photometry as well as for climate forcing calculations. A humidifier-dryer system for a TSI 3563 Nephelometer was designed and built in order to measure the scattering coefficient σsp(λ) at three different wavelengths (λ=440, 550 and 700nm) in a RH range from 30 to 95%. The system was assembled by combining Nafion tubes to humidify and dry the aerosols and stepping motor valves to control the flow and the amount of humidity entering to the Nephelometer. Regular measurements at UMBC (University Of Maryland, Baltimore County) with ambient and lab-generated aerosols have been taking place to study the hygroscopic properties of the aerosols in the region. The aerosols have been humidified as high as 95.4% and the measured σsp(λ) were on average more than two times greater than those at low RH. Another important parameter used to evaluate the hygroscopic properties of aerosols is the enhancement factor f(λ,RH) which is defined as the σsp(λ,RH) at any specified RH divided by the dry σsp(λ,DRY). Initial results indicates that the enhancement factor for ambient aerosols in the region is f(550,94%) =1.35. Enhancement

  3. Implementation of the Missing Aerosol Physics into LLNL IMPACT

    SciTech Connect

    Chuang, C

    2005-02-09

    In recent assessments of climate forcing, the Intergovernmental Panel on Climate Change lists aerosol as one o f the most important anthropogenic agents that influence climate. Atmospheric aerosols directly affect the radiative fluxes at the surface and top of the Earth's atmosphere by scattering and/or absorbing radiation. Further, aerosols indirectly change cloud microphysical properties (such as cloud drop effective radius) that also affect the radiative fluxes. However, the estimate of the magnitude of aerosol climatic effect varies widely, and aerosol/cloud interactions remain one of the most uncertain aspects of climate models today. The Atmospheric Sciences Division has formulated a plan to enhance and expand our modeling expertise in aerosol/cloud/climate interactions. Under previous LDRD support, we successfully developed a computationally efficient version of IMPACT to simulate aerosol climatology. This new version contains a compact chemical mechanism for the prediction of sulfate and also predicts the distributions of organic carbon (OC), black carbon (BC), dust, and sea salt. Furthermore, we implemented a radiation package into IMPACT to calculate the radiative forcing and heating/cooling rates by aerosols. This accomplishment built the foundation of our currently funded projects under the NASA Global Modeling and Analysis Program as well as the DOE Atmospheric Radiation Program. Despite the fact that our research is being recognized as an important effort to quantify the effects of anthropogenic aerosols on climate, the major shortcoming of our previous simulations on aerosol climatic effects is the over simplification of spatial and temporal variations of aerosol size distributions that are shaped by complicated nucleation, growth, transport and removal processes. Virtually all properties of atmospheric aerosols and clouds depend strongly on aerosol size distribution. Moreover, molecular processing on aerosol surfaces alters the hygroscopic

  4. Aerosol optical depth increase in partly cloudy conditions

    SciTech Connect

    Chand, Duli; Wood, R.; Ghan, Steven J.; Wang, Minghuai; Ovchinnikov, Mikhail; Rasch, Philip J.; Miller, Steven D.; Schichtel, Bret; Moore, Tom

    2012-09-14

    Remote sensing observations of aerosol from surface and satellite instruments are extensively used for atmospheric and climate research. From passive sensors, the apparent cloud-free atmosphere in the vicinity of clouds often appears to be brighter then further away from the clouds, leading to an enhancement in the retrieved aerosol optical depth. Mechanisms contributing to this enhancement, including contamination by undetected clouds, hygroscopic growth of aerosol particles, and meteorological conditions, have been debated in recent literature, but an extent to which each of these factors influence the observed enhancement is poorly known. Here we used 11 years of daily global observations at 10x10 km2 resolution from the MODIS on the NASA Terra satellite to quantify as a function of cloud fraction (CF). Our analysis reveals that, averaged over the globe, the clear sky is enhanced by ? = 0.05 which corresponds to relative enhancements of 25% in cloudy conditions (CF=0.8-0.9) compared with relatively clear conditions (CF=0.1-0.2). Unlike the absolute enhancement ?, the relative increase in ? is rather consistent in all seasons and is 25-35% in the subtropics and 15-25% at mid and higher latitudes. Using a simple Gaussian probability density function model to connect cloud cover and the distribution of relative humidity, we argue that much of the enhancement is consistent with aerosol hygroscopic growth in the humid environment surrounding clouds. Consideration of these cloud-dependent effects will facilitate understanding aerosol-cloud interactions and reduce the uncertainty in estimates of aerosol radiative forcing by global climate models.

  5. Results and recommendations from an intercomparison of six Hygroscopicity-TDMA systems

    NASA Astrophysics Data System (ADS)

    Massling, A.; Niedermeier, N.; Hennig, T.; Fors, E. O.; Swietlicki, E.; Ehn, M.; Hämeri, K.; Villani, P.; Laj, P.; Good, N.; McFiggans, G.; Wiedensohler, A.

    2011-03-01

    The performance of six custom-built Hygrocopicity-Tandem Differential Mobility Analyser (H-TDMA) systems was investigated in the frame of an international calibration and intercomparison workshop held in Leipzig, February 2006. The goal of the workshop was to harmonise H-TDMA measurements and develop recommendations for atmospheric measurements and their data evaluation. The H-TDMA systems were compared in terms of the sizing of dry particles, relative humidity (RH) uncertainty, and consistency in determination of number fractions of different hygroscopic particle groups. The experiments were performed in an air-conditioned laboratory using ammonium sulphate particles or an external mixture of ammonium sulphate and soot particles. The sizing of dry particles of the six H-TDMA systems was within 0.2 to 4.2% of the selected particle diameter depending on investigated size and individual system. Measurements of ammonium sulphate aerosol found deviations equivalent to 4.5% RH from the set point of 90% RH compared to results from previous experiments in the literature. Evaluation of the number fraction of particles within the clearly separated growth factor modes of a laboratory generated externally mixed aerosol was done. The data from the H-TDMAs was analysed with a single fitting routine to investigate differences caused by the different data evaluation procedures used for each H-TDMA. The differences between the H-TDMAs were reduced from +12/-13% to +8/-6% when the same analysis routine was applied. We conclude that a common data evaluation procedure to determine number fractions of externally mixed aerosols will improve the comparability of H-TDMA measurements. It is recommended to ensure proper calibration of all flow, temperature and RH sensors in the systems. It is most important to thermally insulate the aerosol humidification unit and the second DMA and to monitor these temperatures to an accuracy of 0.2 °C. For the correct determination of external mixtures

  6. Hexagonal ice stability and growth in the presence of glyoxal and secondary organic aerosols.

    PubMed

    Daskalakis, Vangelis; Hadjicharalambous, Marios

    2014-09-01

    The presence of ice dominates the microphysics of formation of high altitude cirrus and polar stratospheric clouds, as well as the maturity of thunderstorms. We report on the hexagonal (1h) ice stability and growth in binary as well as multi-compound aerosols in atmospherically relevant conformations. The ubiquitous atmospheric trace gas glyoxal along with secondary organic aerosol (SOA) also in the presence of CO2 interacts with large ice 1h crystals of 1300-2000 water molecules. The crystals are subjected to phase transitions under superheating and supercooling conditions by Molecular Dynamics (MD) simulations. Density Functional Theory (DFT) based geometry optimization and vibrational frequency analysis are also employed for a smaller ice 1h cell of 12 water molecules. The interaction of the latter with each organic molecule reveals the extent of the mechanical stress exerted on the ordered ice structure. Full hydration of glyoxal promotes ice 1h stability and growth in wet aerosols, while partial hydration or full oxidation exerts a destabilizing effect on the ice 1h lattice. This behavior is associated with the ability of each organic phase to match the order of the ice 1h crystal. We propose that aqueous chemistry in wet aerosols may also have a strong effect on the microphysics of cloud formation. PMID:25033409

  7. Aerosol light-scattering enhancement due to water uptake during TCAP campaign

    NASA Astrophysics Data System (ADS)

    Titos, G.; Jefferson, A.; Sheridan, P. J.; Andrews, E.; Lyamani, H.; Alados-Arboledas, L.; Ogren, J. A.

    2014-02-01

    Aerosol optical properties were measured by the DOE/ARM (US Department of Energy Atmospheric Radiation Measurements) Program Mobile Facility in the framework of the Two-Column Aerosol Project (TCAP) deployed at Cape Cod, Massachusetts, for a~one year period (from summer 2012 to summer 2013). Measured optical properties included aerosol light-absorption coefficient (σap) at low relative humidity (RH) and aerosol light-scattering coefficient (σsp) at low and at RH values varying from 30 to 85%, approximately. Calculated variables included the single scattering albedo (SSA), the scattering Ångström exponent (SAE) and the scattering enhancement factor (f(RH)). Over the period of measurement, f(RH = 80%) had a mean value of 1.9 ± 0.3 and 1.8 ± 0.4 in the PM10 and PM1 fractions, respectively. Higher f(RH = 80%) values were observed for wind directions from 0-180° (marine sector) together with high SSA and low SAE values. The wind sector from 225 to 315° was identified as an anthropogenically-influenced sector, and it was characterized by smaller, darker and less hygroscopic aerosols. For the marine sector, f(RH = 80%) was 2.2 compared with a value of 1.8 obtained for the anthropogenically-influenced sector. The air-mass backward trajectory analysis agreed well with the wind sector analysis. It shows low cluster to cluster variability except for air-masses coming from the Atlantic Ocean that showed higher hygroscopicity. Knowledge of the effect of RH on aerosol optical properties is of great importance for climate forcing calculations and for comparison of in-situ measurements with satellite and remote sensing retrievals. In this sense, predictive capability of f(RH) for use in climate models would be enhanced if other aerosol parameters could be used as proxies to estimate hygroscopic growth. Toward this goal, we propose an exponential equation that successfully estimates aerosol hygroscopicity as a function of SSA at Cape Cod. Further work is needed to determine

  8. Aerosol light-scattering enhancement due to water uptake during the TCAP campaign

    NASA Astrophysics Data System (ADS)

    Titos, G.; Jefferson, A.; Sheridan, P. J.; Andrews, E.; Lyamani, H.; Alados-Arboledas, L.; Ogren, J. A.

    2014-07-01

    Aerosol optical properties were measured by the DOE/ARM (US Department of Energy Atmospheric Radiation Measurements) Program Mobile Facility during the Two-Column Aerosol Project (TCAP) campaign deployed at Cape Cod, Massachusetts, for a 1-year period (from summer 2012 to summer 2013). Measured optical properties included aerosol light-absorption coefficient (σap) at low relative humidity (RH) and aerosol light-scattering coefficient (σsp) at low and at RH values varying from 30 to 85%, approximately. Calculated variables included the single scattering albedo (SSA), the scattering Ångström exponent (SAE) and the scattering enhancement factor (f(RH)). Over the period of measurement, f(RH = 80%) had a mean value of 1.9 ± 0.3 and 1.8 ± 0.4 in the PM10 and PM1 fractions, respectively. Higher f(RH = 80%) values were observed for wind directions from 0 to 180° (marine sector) together with high SSA and low SAE values. The wind sector from 225 to 315° was identified as an anthropogenically influenced sector, and it was characterized by smaller, darker and less hygroscopic aerosols. For the marine sector, f(RH = 80%) was 2.2 compared with a value of 1.8 obtained for the anthropogenically influenced sector. The air-mass backward trajectory analysis agreed well with the wind sector analysis. It shows low cluster to cluster variability except for air masses coming from the Atlantic Ocean that showed higher hygroscopicity. Knowledge of the effect of RH on aerosol optical properties is of great importance for climate forcing calculations and for comparison of in situ measurements with satellite and remote sensing retrievals. In this sense, predictive capability of f(RH) for use in climate models would be enhanced if other aerosol parameters could be used as proxies to estimate hygroscopic growth. Toward this goal, we propose an exponential equation that successfully estimates aerosol hygroscopicity as a function of SSA at Cape Cod. Further work is needed to determine if

  9. Speciation of Organic Aerosols in the Tropical Mid-Pacific and Their Relationship to Light Scattering.

    NASA Astrophysics Data System (ADS)

    Crahan, Kathleen K.; Hegg, Dean A.; Covert, David S.; Jonsson, Haflidi; Reid, Jeffrey S.; Khelif, Djamal; Brooks, Barbara J.

    2004-11-01

    Although the importance of the aerosol contribution to the global radiative budget has been recognized, the forcings of aerosols in general, and specifically the role of the organic component in these forcings, still contain large uncertainties. In an attempt to better understand the relationship between the background forcings of aerosols and their chemical speciation, marine air samples were collected off the windward coast of Oahu, Hawaii, during the Rough Evaporation Duct project (RED) using filters mounted on both the Twin Otter aircraft and the Floating Instrument Platform (FLIP) research platform. Laboratory analysis revealed a total of 17 species, including 4 carboxylic acids and 2 carbohydrates that accounted for 74% ± 20% of the mass gain observed on the shipboard filters, suggesting a possible significant unresolved organic component. The results were correlated with in situ measurements of particle light scattering (σsp) at 550 nm and with aerosol hygroscopicities. Principal component analysis revealed a small but ubiquitous pollution component affecting the σsp and aerosol hygroscopicity of the remote marine air. The Princeton Organic-Electrolyte Model (POEM) was used to predict the growth factor of the aerosols based upon the chemical composition. This output, coupled with measured aerosol size distributions, was used to attempt to reproduce the observed σsp. It was found that while the POEM model was able to reproduce the expected trends when the organic component of the aerosol was varied, due to large uncertainties especially in the aerosol sizing measurements, the σsp predicted by the POEM model was consistently higher than observed.


  10. Hygroscopicity of materials internally mixed with black carbon measured in Tokyo

    NASA Astrophysics Data System (ADS)

    Ohata, Sho; Schwarz, Joshua P.; Moteki, Nobuhiro; Koike, Makoto; Takami, Akinori; Kondo, Yutaka

    2016-01-01

    Black carbon (BC) aerosols become internally mixed with non-BC compounds (BC coatings) during aging in the atmosphere. In this study, we measured the hygroscopicity parameter κ on a single-particle basis for both BC-coating materials (κBC-coat) and BC-free particles (κBC-free) in the urban atmosphere of Tokyo, using a single-particle soot photometer (SP2). In our measurement system, dry ambient particles were first mass selected by an aerosol particle mass analyzer, then humidified, and then passed to the SP2 for detection of their refractory BC mass content and optical diameter. A quadrupole aerosol mass spectrometer was also employed to interpret the hygroscopicity data. During the observation period, the measured κBC-coat generally agreed with κBC-free to within ±25% and was usually in typical range for inorganic and organic aerosols. These results indicate that BC-coating materials and BC-free particles in Tokyo usually had similar chemical compositions, internal mixtures of inorganic and organic compounds, even in a source region. However, occasionally κBC-coat was much higher than κBC-free values, when the mass concentrations of BC and organic aerosols were poorly correlated. This indicates external mixing of BC-containing and BC-free particles from different sources. These findings improve our understanding of the cloud condensation nuclei activity of BC-containing particles, which strongly influences their wet removal, and optical properties in the ambient air.

  11. A relative humidity processing method for the sampling of aerosol particles with low growth-ability

    NASA Astrophysics Data System (ADS)

    Martinsson, Bengt G.; Hansson, Hans-Christen; Asking, Lars; Cederfelt, Sven-Inge

    1992-11-01

    A method for the fractionation of aerosol particles with respect to size and ability to grow with an increased relative humidity has been developed. The system consists of cascade impactors, diffusion driers, a humidifier, and a temperature stabilizer. Diffusion driers were designed and the vapor penetration was modeled below 20 percent. A humidifier which can be operated with an output relative humidity above 95 percent was developed. Flow-rates up to 51/min can be used and the relative humidity can be controlled within approximately 1 percent. The ability of the system to fractionate aerosol particles with respect to growth with relative humidity was investigated. The equivalent aerodynamic diameter growth factor for sodium chloride was determined to 2 at a relative humidity of 98 percent, in good agreement with theory.

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

    NASA Astrophysics Data System (ADS)

    Verheggen, B.; Mozurkewich, M.

    2003-04-01

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

  13. Direct radiative effect by multicomponent aerosol over China

    SciTech Connect

    Huang, Xin; Song, Yu; Zhao, Chun; Cai, Xuhui; Zhang, Hongsheng; Zhu, Tong

    2015-05-01

    The direct radiative effect (DRE) of multiple aerosol species (sulfate, nitrate, ammonium, black carbon (BC), organic carbon (OC), and mineral aerosol) and their spatiotemporal variations over China were investigated using a fully coupled meteorology–chemistry model (WRF-Chem) for the entire year of 2006. We made modifications to improve model performance, including updating land surface parameters, improving the calculation of transition metal-catalyzed oxidation of SO2, and adding in heterogeneous reactions between mineral aerosol and acid gases. The modified model well reproduced the magnitude, seasonal pattern, and spatial distribution of the measured meteorological conditions, concentrations of PM10 and its components, and aerosol optical depth (AOD). A diagnostic iteration method was used to estimate the overall DRE of aerosols and contributions from different components. At the land surface, all kinds of aerosol species reduced the incident net radiation flux with a total DRE of 10.2 W m-2 over China. Aerosols significantly warm the atmosphere with the national mean DRE of +10.8 W m-2. BC was the leading radiative-heating component (+8.7 W m-2), followed by mineral aerosol (+1.1 W m-2). At the top of the atmosphere (TOA), BC introduced the largest radiative perturbation (+4.5 W m-2), followed by sulfate (-1.4 W m-2). The overall perturbation of aerosols on radiation transfer is quite small over China, demonstrating the counterbalancing effect between scattering and adsorbing aerosols. Aerosol DRE at the TOA had distinct seasonality, generally with a summer maximum and winter minimum, mainly determined by mass loadings, hygroscopic growth, and incident radiation flux.

  14. 21 CFR 884.4260 - Hygroscopic Laminaria cervical dilator.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Hygroscopic Laminaria cervical dilator. 884.4260 Section 884.4260 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... Devices § 884.4260 Hygroscopic Laminaria cervical dilator. (a) Identification. A hygroscopic...

  15. 21 CFR 884.4260 - Hygroscopic Laminaria cervical dilator.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Hygroscopic Laminaria cervical dilator. 884.4260 Section 884.4260 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... Devices § 884.4260 Hygroscopic Laminaria cervical dilator. (a) Identification. A hygroscopic...

  16. The time dependent growth of H2O-H2SO4 aerosols by heteromolecular condensation

    NASA Technical Reports Server (NTRS)

    Hamill, P.

    1975-01-01

    A theory for the time-dependent growth of solution droplets by heteromolecular condensation is presented. The theory is applied to the growth of H2O-H2SO4 aerosols for relative humidities less than 100 per cent. Growth curves (droplet radius as a function of time) for different values of relative humidity are evaluated.

  17. Morphological characterization of soot aerosol particles during LACIS Experiment in November (LExNo)

    NASA Astrophysics Data System (ADS)

    Kiselev, A.; Wennrich, C.; Stratmann, F.; Wex, H.; Henning, S.; Mentel, T. F.; Kiendler-Scharr, A.; Schneider, J.; Walter, S.; Lieberwirth, I.

    2010-06-01

    Combined mobility and aerodynamic measurements were used to characterize the morphology of soot particles in an experimental campaign on the hygroscopic growth and activation of an artificial biomass burning aerosol. A custom-made, single-stage low-pressure impactor and two aerosol mass spectrometers (AMS) operating in the free molecular regime were used to measure the vacuum aerodynamic diameter of mobility-selected artificial soot particles that were produced in a spark discharge generator and then modified by condensation of ammonium hydrogen sulfate or levoglucosan as a coating to change their hydroscopic activity. Transmission electron microscope images revealed a relationship between the electrical mobility diameter and the diameter of the enveloping sphere, thus enabling evaluation of the effective density of soot agglomerates. A fractal description of the morphology of the soot aggregates allowed for evaluation of the average mass of the hygroscopic material per particle. The average mass of the hygroscopic material per particle was also measured directly with the two AMS instruments, and the agreement between the two methods was found satisfactory. This tandem approach allows detection of small changes in the particle effective density and morphology caused by condensation of organic material.

  18. Growth conditions and environmental factors impact aerosolization but not virulence of Francisella tularensis infection in mice

    PubMed Central

    Faith, Seth A.; Smith, Le'Kneitah P.; Swatland, Angela S.; Reed, Douglas S.

    2012-01-01

    In refining methodology to develop a mouse model for inhalation of Francisella tularensis, it was noted that both relative humidity and growth media impacted the aerosol concentration of the live vaccine strain (LVS) of F. tularensis. A relative humidity of less than 55% had a negative impact on the spray factor, the ratio between the concentration of LVS in the aerosol and the nebulizer. The spray factor was significantly higher for LVS grown in brain heart infusion (BHI) broth than LVS grown in Mueller–Hinton broth (MHb) or Chamberlain's chemically defined medium (CCDM). The variability between aerosol exposures was also considerably less with BHI. LVS grown in BHI survived desiccation far longer than MHb-grown or CCDM-grown LVS (~70% at 20 min for BHI compared to <50% for MHb and CCDM). Removal of the capsule by hypertonic treatment impacted the spray factor for CCDM-grown LVS or MHb-grown LVS but not BHI-grown LVS, suggesting the choice of culture media altered the adherence of the capsule to the cell membrane. The choice of growth media did not impact the LD50 of LVS but the LD99 of BHI-grown LVS was 1 log lower than that for MHb-grown LVS or CCDM-grown LVS. Splenomegaly was prominent in mice that succumbed to MHb- and BHI-grown LVS but not CCDM-grown LVS. Environmental factors and growth conditions should be evaluated when developing new animal models for aerosol infection, particularly for vegetative bacterial pathogens. PMID:23087911

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  20. Formation and growth of organic aerosols downwind of the Deepwater Horizon oil spill

    NASA Astrophysics Data System (ADS)

    Brock, Charles A.; Murphy, Daniel M.; Bahreini, Roya; Middlebrook, Ann M.

    2011-09-01

    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. Previous work has shown that rapid condensation of partially oxidized hydrocarbons was responsible for formation of a plume of secondary organic aerosol downwind of the spill region. Here we examine new particle formation and growth kinetics. New particles were formed upwind of the freshest oil but downwind of oil that surfaced less than about 100 hours previously. Four nm particles formed at a rate of ˜3 cm-3 s-1 and subsequently grew by condensation at a rate 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 irreversible growth with unit accommodation coefficient is estimated to be ˜0.04-0.09 μg m-3 (˜3-8 pptv). Gas-phase concentrations may have been higher if condensation were limited by volatility. The ratio of growth rates for newly formed particles to accumulation mode particles was consistent within error limits with irreversible condensation. The absence of new particle formation away from the <100 hr-old oil slick indicates that the oxidation products of gas-phase hydrocarbon species were directly involved in the formation and growth of new particles.

  1. Size-resolved aerosol water uptake and cloud condensation nuclei measurements as measured above a Southeast Asian rainforest during OP3

    NASA Astrophysics Data System (ADS)

    Irwin, M.; Robinson, N.; Allan, J. D.; Coe, H.; McFiggans, G.

    2011-01-01

    The influence of the properties of fine particles on the formation of clouds and precipitation in the tropical atmosphere is of primary importance to their impacts on radiative forcing and the hydrological cycle. Measurements of aerosol number size distribution, hygroscopicity in both sub- and supersaturated regimes and composition were taken between March and July 2008 in the tropical rainforest in Borneo, Malaysia, marking the first study of this type in an Asian tropical rainforest. Hygroscopic growth factors (GF) at 90% relative humidity (RH) for the dry diameter range D0=32-258 nm, supersaturated water uptake behaviour for the dry diameter range D0=20-300 nm and aerosol chemical composition were simultaneously measured using a Hygroscopicity Tandem Differential Mobility Analyser (HTDMA), a Droplet Measurement Technologies Cloud Condensation Nuclei counter (CCNc) and an Aerodyne Aerosol Mass Spectrometer (AMS), respectively. The derived hygroscopicty parameter κ ranged from between 0.05-0.37 for the supersaturation range 0.11-0.73% compared to those between 0.17-0.37 for measurements performed at a relative humidity of 90%. In contrast, results from a study with similar methodology performed in the Amazon basin report more similar values for κ, indicating that the aerosol as measured from both sites shows similar hygroscopic properties. However, the derived number of cloud condensation nuclei (NCCN) were much higher than those measured in the Amazon, due to the higher particle number concentrations in the rainforests of Borneo. This first contrast between the two environments may be of substantial importance in describing the impacts of particles in the tropical atmosphere.

  2. Measurements of submicron aerosols at the California-Mexico border during the Cal-Mex 2010 field campaign

    NASA Astrophysics Data System (ADS)

    Levy, Misti E.; Zhang, Renyi; Zheng, Jun; Tan, Haobo; Wang, Yuan; Molina, Luisa T.; Takahama, S.; Russell, L. M.; Li, Guohui

    2014-05-01

    We present measurements of submicron aerosols in Tijuana, Mexico during the Cal-Mex 2010 field campaign. A suite of aerosol instrumentations were deployed, including a hygroscopic-volatility tandem differential mobility analyzer (HV-TDMA), aerosol particle mass analyzer (APM), condensation particle counter (CPC), cavity ring-down spectrometer (CRDS), and nephelometer to measure the aerosol size distributions, effective density, hygroscopic growth factors (HGF), volatility growth factors (VGF), and optical properties. The average mass concentration of PM0.6 is 10.39 ± 7.61 μg m-3, and the derived average black carbon (BC) mass concentration is 2.87 ± 2.65 μg m-3. There is little new particle formation or particle growth during the day, and the mass loading is dominated by organic aerosols and BC, which on average are 37% and 27% of PM1.0, respectively. For four particle sizes of 46, 81, 151, and 240 nm, the measured particle effective density, HGFs, and VGFs exhibit distinct diurnal trends and size-dependence. For smaller particles (46 and 81 nm), the effective density distribution is unimodal during the day and night, signifying an internally mixed aerosol composition. In contrast, larger particles (151 and 240 nm) exhibit a bi-modal effective density distribution during the daytime, indicating an external mixture of fresh BC and organic aerosols, but a unimodal distribution during the night, corresponding to an internal mixture of BC and organic aerosols. The smaller particles show a noticeable diurnal trend in the effective density distribution, with the highest effective density (1.70 g cm-3) occurring shortly after midnight and the lowest value (0.90 g cm-3) occurring during the afternoon, corresponding most likely to primary organic aerosols and BC, respectively. Both HGFs and VGFs measured are strongly size-dependent. HGFs increase with increasing particle size, indicating that the largest particles are more hygroscopic. VGFs decrease with increasing

  3. 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.

  4. Growth and characterization of nanostructured aerosol produced by diffusion flame and spray pyrolysis methods

    NASA Astrophysics Data System (ADS)

    Kim, Soo Hyung

    The present research is aimed at developing methods to characterize and study the growth of nano-particles and nano-structured materials. The thesis is divided into two parts. One part deals with the development of the tandem differential mobility analyzer (TDMA), which is the principal method used in this study to characterize the size and electrical charge of particles formed in a high temperature flame. The second part of the thesis deals with the formation of nano-structured materials with zeolite-type structures. The particles are characterized to determine their size, porosity and surface area. It is well known that nano-sized aerosol particles from combustion sources are charged. Even though the basic charging mechanisms are reasonably well understood qualitatively, techniques for characterizing the charge and size distribution of aerosols from combustion sources are not well developed. In the present study, a method is developed to accurately measure the charge and size distribution of nano-sized combustion aerosols by means of a TDMA. From a series of TDMA measurements, the charge fraction of nano-sized soot particles from a flame is obtained as a function of equivalent mobility particle diameter ranging from 50 to 200nm. The method is then used to characterize the size and charge of combustion aerosols. The results are compared to theory, including the new theory developed in this study. To develop a new synthetic method of nano-structured aerosol particles, a thermal tubular reactor is employed. New spray-pyrolytic and aerosol-gel methods are developed to form nanoporous metal oxides, in which thermally stable and easily leached inorganic matrix is employed to extend the porosity of zeolite-typed materials. The characteristics of the nanoporous material, such as surface area and particle morphology are investigated as a function of relative humidity, temperature, and precursor fractions. The physical and chemical properties of materials synthesized are

  5. Modeling of growth and evaporation effects on the extinction of 1.0-micron solar radiation traversing stratospheric sulfuric acid aerosols

    NASA Technical Reports Server (NTRS)

    Yue, G. K.; Deepak, A.

    1981-01-01

    The effects of growth and evaporation of stratospheric sulfuric acid aerosols on the extinction of solar radiation traversing such an aerosol medium are reported for the case of 1.0-micron solar radiation. Modeling results show that aerosol extinction is not very sensitive to the change of ambient water vapor concentration, but is sensitive to ambient temperature changes, especially at low ambient temperatures and high ambient water vapor concentration. A clarification is given of the effects of initial aerosol size distribution and composition on the change of aerosol extinction due to growth and evaporation processes. It is shown that experiments designed to observe solar radiation extinction of aerosols may also be applied to the determination of observed changes in aerosol optical properties, environmental parameters, or the physical and optical characteristics of sulfate aerosols.

  6. RELATIONSHIP BETWEEN MEASURED WATER VAPOR GROWTH AND CHEMISTRY OF ATMOSPHERIC AEROSOL FOR GRAND CANYON, ARIZONA, IN WINTER 1990.

    EPA Science Inventory

    Size-resolved aerosol growth measurements (growth = moist particle diameter/dry particle diameter) and chemical composition monitoring were conducted during a 3 month period in the winter of 1990 at the South Rim of Grand Canyon National Park, AZ as part of the Navajo Generating ...

  7. Importance of relative humidity in the oxidative ageing of organic aerosols: case study of the ozonolysis of maleic acid aerosol

    NASA Astrophysics Data System (ADS)

    Gallimore, P. J.; Achakulwisut, P.; Pope, F. D.; Davies, J. F.; Spring, D. R.; Kalberer, M.

    2011-12-01

    Many important atmospheric aerosol processes depend on the chemical composition of the aerosol, e.g. water uptake and particle cloud interactions. Atmospheric ageing processes, such as oxidation reactions, significantly and continuously change the chemical composition of aerosol particles throughout their lifetime. These ageing processes are often poorly understood. In this study we utilize an aerosol flow tube set up and an ultra-high resolution mass spectrometer to explore the effect of relative humidity (RH) in the range of <5-90% on the ozonolysis of maleic acid aerosol which is employed as model organic aerosol system. Due to the slow reaction kinetics relatively high ozone concentrations of 160-200 ppm were used to achieve an appreciable degree of oxidation of maleic acid. The effect of oxidative ageing on the hygroscopicity of maleic acid particles is also investigated using an electrodynamic balance and thermodynamic modelling. RH has a profound effect on the oxidation of maleic acid particles. Very little oxidation is observed at RH < 50% and the only observed reaction products are glyoxylic acid and formic acid. In comparison, when RH > 50% there are about 15 oxidation products identified. This increased oxidation was observed even when the particles were exposed to high humidities long after a low RH ozonolysis reaction. This result might have negative implications for the use of water as an extraction solvent for the analysis of oxidized organic aerosols. These humidity-dependent differences in the composition of the ozonolyzed aerosol demonstrate that water is both a key reactant in the oxidation scheme and a determinant of particle phase and hence diffusivity. The measured chemical composition of the processed aerosol is used to model the hygroscopic growth, which compares favourably with water uptake results from the electrodynamic balance measurements. A reaction mechanism is presented which takes into account the RH dependent observations. This

  8. An intensive study on aerosol optical properties and affecting factors in Nanjing, China.

    PubMed

    Cui, Fenping; Chen, Mindong; Ma, Yan; Zheng, Jun; Zhou, Yaoyao; Li, Shizheng; Qi, Lu; Wang, Li

    2016-02-01

    The optical properties of aerosol as well as their impacting factors were investigated at a suburb site in Nanjing during autumn from 14 to 28 November 2012. More severe pollution was found together with lower visibility. The average scattering and absorption coefficients (Bsca and Babs) were 375.7 ± 209.5 and 41.6 ± 18.7 Mm(-1), respectively. Higher Ångström absorption and scattering exponents were attributed to the presence of more aged aerosol with smaller particles. Relative humidity (RH) was a key factor affecting aerosol extinction. High RH resulted in the impairment of visibility, with hygroscopic growth being independent of the dry extinction coefficient. The hygroscopic growth factor was 1.8 ± 1.2 with RH from 19% to 85%. Light absorption was enhanced by organic carbon (OC), elemental carbon (EC) and EC coatings, with contributions of 26%, 44% and 75% (532 nm), respectively. The Bsca and Babs increased with increasing N100 (number concentration of PM2.5 with diameter above 100 nm), PM1 surface concentration and PM2.5 mass concentration with good correlation. PMID:26969543

  9. Demonstration of Aerosol Property Profiling by Multi-wavelength Lidar Under Varying Relative Humidity Conditions

    NASA Technical Reports Server (NTRS)

    Whiteman, D.N.; Veselovskii, I.; Kolgotin, A.; Korenskii, M.; Andrews, E.

    2008-01-01

    The feasibility of using a multi-wavelength Mie-Raman lidar based on a tripled Nd:YAG laser for profiling aerosol physical parameters in the planetary boundary layer (PBL) under varying conditions of relative humidity (RH) is studied. The lidar quantifies three aerosol backscattering and two extinction coefficients and from these optical data the particle parameters such as concentration, size and complex refractive index are retrieved through inversion with regularization. The column-integrated, lidar-derived parameters are compared with results from the AERONET sun photometer. The lidar and sun photometer agree well in the characterization of the fine mode parameters, however the lidar shows less sensitivity to coarse mode. The lidar results reveal a strong dependence of particle properties on RH. The height regions with enhanced RH are characterized by an increase of backscattering and extinction coefficient and a decrease in the Angstrom exponent coinciding with an increase in the particle size. We present data selection techniques useful for selecting cases that can support the calculation of hygroscopic growth parameters using lidar. Hygroscopic growth factors calculated using these techniques agree with expectations despite the lack of co-located radiosonde data. Despite this limitation, the results demonstrate the potential of multi-wavelength Raman lidar technique for study of aerosol humidification process.

  10. 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

  11. 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

  12. Study of aerosol optical properties at Kunming in southwest China and long-range transport of biomass burning aerosols from North Burma

    NASA Astrophysics Data System (ADS)

    Zhu, J.; Xia, X.; Che, H.; Wang, J.; Zhang, J.; Duan, Y.

    2016-03-01

    Seasonal variation of aerosol optical properties and dominant aerosol types at Kunming (KM), an urban site in southwest China, is characterized. Substantial influences of the hygroscopic growth and long-range transport of biomass burning (BB) aerosols on aerosol optical properties at KM are revealed. These results are derived from a detailed analysis of (a) aerosol optical properties (e.g. aerosol optical depth (AOD), columnar water vapor (CWV), single scattering albedo (SSA) and size distribution) retrieved from sunphotometer measurements during March 2012-August 2013, (b) satellite AOD and active fire products, (c) the attenuated backscatter profiles from the space-born lidar, and (d) the back-trajectories. The mean AOD440nm and extinction Angstrom exponent (EAE440 - 870) at KM are 0.42 ± 0.32 and 1.25 ± 0.35, respectively. Seasonally, high AOD440nm (0.51 ± 0.34), low EAE440 - 870 (1.06 ± 0.34) and high CWV (4.25 ± 0.97 cm) during the wet season (May - October) contrast with their counterparts 0.17 ± 0.11, 1.40 ± 0.31 and 1.91 ± 0.37 cm during the major dry season (November-February) and 0.53 ± 0.29, 1.39 ± 0.19, and 2.66 ± 0.44 cm in the late dry season (March-April). These contrasts between wet and major dry season, together with the finding that the fine mode radius increases significantly with AOD during the wet season, suggest the importance of the aerosol hygroscopic growth in regulating the seasonal variation of aerosol properties. BB and Urban/Industrial (UI) aerosols are two major aerosol types. Back trajectory analysis shows that airflows on clean days during the major dry season are often from west of KM where the AOD is low. In contrast, air masses on polluted days are from west (in late dry season) and east (in wet season) of KM where the AOD is often large. BB air mass is found mostly originated from North Burma where BB aerosols are lifted upward to 5 km and then subsequently transported to southwest China via prevailing westerly winds.

  13. Impacts of Aminium Sulfates on Atmospheric Aerosol Properties

    NASA Astrophysics Data System (ADS)

    Qiu, C.; Zhang, R.

    2012-12-01

    Atmospheric aerosols influence our environment significantly by interacting with the solar radiation and modifying cloud formation processes. Amines are emitted into the atmosphere from various anthropogenic and biogenic sources. Recent studies have shown that atmospheric amines can enter the particle-phase as salts like aminium sulfates by reacting with aerosol constituents including sulfuric acid and ammonium salts. However, little knowledge is available about the properties of these aminium salts and their impacts on aerosol properties. We have conducted laboratory experiments to measure the hygroscopicity, thermostability, and density of five representative alkylaminium sulfates, using an integrated aerosol analytical system including a tandem differential mobility analyzer and an aerosol particle mass analyzer. When exposed to increasing RH, alkylaminium sulfate aerosols show monotonic growth in size without a well-defined deliquescence point. Aerosols of mixed ammonium-alkylaminium sulfates have deliquescence points lower than that of ammonium sulfate. The measurements of thermostability reveal that dimethylaminium sulfate is the most stable species upon heating. Trimethyl- and triethyl-aminium sulfates volatilize similarly to ammonium sulfate, but exhibit lower volatility than monomethyl- and diethyl-aminium sulfates. The density of alkylaminium sulfates ranges from 1.2 to 1.5 g cm-3, and can be predicted from an empirical model on the basis of the mole ratio of alkyl carbons to total sulfate. Our results suggest that the properties of aerosols may be considerably altered by the incorporation of atmospheric amines through heterogeneous reactions. In particular, these processes may lead to an enhanced water uptake at low RH and considerably change the contribution of aerosols to climate forcing.

  14. Hygroscopic salts and the potential for life on Mars.

    PubMed

    Davila, Alfonso F; Duport, Luis Gago; Melchiorri, Riccardo; Jänchen, Jochen; Valea, Sergio; de Los Rios, Asunción; Fairén, Alberto G; Möhlmann, Diedrich; McKay, Christopher P; Ascaso, Carmen; Wierzchos, Jacek

    2010-01-01

    Hygroscopic salts have been detected in soils in the northern latitudes of Mars, and widespread chloride-bearing evaporitic deposits have been detected in the southern highlands. The deliquescence of hygroscopic minerals such as chloride salts could provide a local and transient source of liquid water that would be available for microorganisms on the surface. This is known to occur in the Atacama Desert, where massive halite evaporites have become a habitat for photosynthetic and heterotrophic microorganisms that take advantage of the deliquescence of the salt at certain relative humidity (RH) levels. We modeled the climate conditions (RH and temperature) in a region on Mars with chloride-bearing evaporites, and modeled the evolution of the water activity (a(w)) of the deliquescence solutions of three possible chloride salts (sodium chloride, calcium chloride, and magnesium chloride) as a function of temperature. We also studied the water absorption properties of the same salts as a function of RH. Our climate model results show that the RH in the region with chloride-bearing deposits on Mars often reaches the deliquescence points of all three salts, and the temperature reaches levels above their eutectic points seasonally, in the course of a martian year. The a(w) of the deliquescence solutions increases with decreasing temperature due mainly to the precipitation of unstable phases, which removes ions from the solution. The deliquescence of sodium chloride results in transient solutions with a(w) compatible with growth of terrestrial microorganisms down to 252 K, whereas for calcium chloride and magnesium chloride it results in solutions with a(w) below the known limits for growth at all temperatures. However, taking the limits of a(w) used to define special regions on Mars, the deliquescence of calcium chloride deposits would allow for the propagation of terrestrial microorganisms at temperatures between 265 and 253 K, and for metabolic activity (no growth) at

  15. Subarctic atmospheric aerosol composition: 3. Measured and modeled properties of cloud condensation nuclei

    SciTech Connect

    Kammermann, Lukas; Gysel, Martin; Weingartner, E.; Herich, Hanna; Holst, Thomas; Cziczo, Daniel J.; Svenningsson, Birgitta; Arneth, Almut; Baltensperger, Urs

    2010-02-19

    Predicting the ability of aerosol particles to act as cloud condensation nuclei (CCN) is still a challenge and not properly incorporated in current climate models. By using field data from measurements at the sub-arctic Stordalen site, approximately 200 km north of the Arctic Circle, a hygroscopicity closure study was performed. Measured CCN number concentrations were compared with predictions that involved size distribution data and hygroscopicity data measured by a HTDMA as a proxy for the chemical composition of the aerosol. The sensitivity of the predictions to simplifying assumptions re-garding mixing state of the particles and the temporal variability of the chemical composition were explored. It was found that involving the full growth factor probability density function (GF-PDF) or the averaged growth factor (GF) or a constant averaged κ-value resulted in reasonable agreement be-tween predicted and measured CCN number concentrations. Probability distribution histograms of the performances of the different closure approaches revealed that involving the full GF-PDF resulted in the narrowest and most symmetric distribution of the predicted-to-measured CCN number concentra-tion ratio around unity. While also involving the averaged GF showed a good agreement, the constant averaged κ-value-approach resulted in most of the cases in an overestimation of CCN number con-centrations by ~15 %. Approaches where a constant estimated hygroscopicity was involved predicted CCN number concentrations in some cases well but largely overestimated (assuming internally mixed ammonium sulphate particles) or underestimated (assuming internally mixed organic aerosol particles with κ = 0.1) CCN number concentrations. It is therefore recommended that at least an averaged measured proxy for the aerosol’s chemical composition be incorporated in future CCN predictions and climate models.

  16. Growth of aerosols in Titan's atmosphere and related time scales - A stochastic approach

    NASA Astrophysics Data System (ADS)

    Rannou, P.; Cabane, M.; Chassefiere, E.

    1993-05-01

    The evolution of Titan's aerosols is studied from their production altitude down to the ground using a stochastic approach. A background aerosol distribution is assumed, obtained from previous Eulerian modelling. and the evolution of a 'tagged' particle, released near the formation altitude, is followed by simulating in a random way its growth through coagulation with particles of the background distribution. The two distinct growth stages proposed by Cabane et al. (1992) to explain the formation of monomers and subsequent aggregates are confirmed. The first stage may be divided into two parts. First, within roughly one terrestrial day, particles grow mainly through collisions with larger particles. They reach the size of monomer through typically one to five such collisions. Second, within a few terrestrial days to roughly one terrestrial month, particles evolve mainly by collisions with continuously created small particles and acquire their compact spherical structure. In the second stage, whose duration is roughly 30 terrestrial years, or one Titan's seasonal cycle, particles grow by cluster-cluster aggregation during their fall through the atmosphere and reach, at low stratospheric levels, a typical radius of 0.4-0.5 micron.

  17. Large differences in aerosol optical properties over the north-west Atlantic Ocean during the TCAP field campaign

    NASA Astrophysics Data System (ADS)

    Chand, D.; Berg, L. K.; Comstock, J. M.; Fast, J. D.; Flynn, C. J.; Hubbe, J. M.; Kassianov, E.; Mei, F.; Pekour, M. S.; Schmid, B.; Sedlacek, A. J., III; Tomlinson, J. M.; Shilling, J. E.; Wilson, J. M.; Zelenyuk, A.; Berkowitz, C. M.

    2014-12-01

    Aerosol radiative forcing is an important parameter in the Earth's radiation budget and can be an important driver of atmospheric circulation and the hydrological cycle. Accurate estimation of aerosol radiative forcing requires measurement of both the extensive and intensive optical properties of aerosols. While the intensive optical properties are independent of aerosol mass or number, they are critical inputs when calculating radiative forcing with applications to climate research, satellite remote sensing and model validations. The key aerosol intensive properties that need to be evaluated include single scattering albedo (SSA), the angstrom exponent, the asymmetry parameter, the radiative forcing efficiency, and the hygroscopic scattering factor. We report here on values of these variables over the Cape Cod and nearby northwest Atlantic Ocean during the Two Column Aerosol Project (TCAP). The average SSA shows a distinct profile having higher SSA values below the top of well-mixed residual layer (RL) and lower SSA above it. Aerosol in the free troposphere (FT) were found to have less spectral dependence in their optical properties, lower back scatter fraction and higher hygroscopic growth relative to aerosols found in the RL. Analysis of individual particle composition suggests that that ratio of aged to fresh aerosol numbers in the FT is 70% higher compared to aerosols measured in the RL, and that smoke from biomass burning contributed ~10% to this number. Single particle analysis also reveals that the fraction and variability of coated black carbon (BC) aerosol is higher in the FT relative to that measured in the residual layer. The daily radiative forcing efficiency of these aerosols in the FT is factor 2 higher than below RL. Seven years (2007-2013) of CALIPSO satellite observations show that the mean altitude of the top of smoke layers (~3.3 km) consistent with these in situ observations from TCAP. Overall, the long term CALIPSO observations characterizes

  18. Size-dependent hygroscopicity parameter (κ) and chemical composition of secondary organic cloud condensation nuclei

    NASA Astrophysics Data System (ADS)

    Zhao, D. F.; Buchholz, A.; Kortner, B.; Schlag, P.; Rubach, F.; Kiendler-Scharr, A.; Tillmann, R.; Wahner, A.; Flores, J. M.; Rudich, Y.; Watne, À. K.; Hallquist, M.; Wildt, J.; Mentel, Th. F.

    2015-12-01

    Secondary organic aerosol components (SOA) contribute significantly to the activation of cloud condensation nuclei (CCN) in the atmosphere. The CCN activity of internally mixed submicron SOA particles is often parameterized assuming a size-independent single-hygroscopicity parameter κ. In the experiments done in a large atmospheric reactor (SAPHIR, Simulation of Atmospheric PHotochemistry In a large Reaction chamber, Jülich), we consistently observed size-dependent κ and particle composition for SOA from different precursors in the size range of 50 nm-200 nm. Smaller particles had higher κ and a higher degree of oxidation, although all particles were formed from the same reaction mixture. Since decreasing volatility and increasing hygroscopicity often covary with the degree of oxidation, the size dependence of composition and hence of CCN activity can be understood by enrichment of higher oxygenated, low-volatility hygroscopic compounds in smaller particles. Neglecting the size dependence of κ can lead to significant bias in the prediction of the activated fraction of particles during cloud formation.

  19. Hygroscopic chemicals and the formation of advection warm fog: A numerical simulation

    NASA Technical Reports Server (NTRS)

    Hung, R. J.; Liaw, G. S.

    1978-01-01

    The formation of advection fog is closely associated with the characteristics of the aerosol particles, including the chemical composition, mass of the nuclei, particle size, and concentration. 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.

  20. 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

  1. Pampre : a new laboratory experiment to better understand the physico-chemical processes of Titan aerosols formation and growth

    NASA Astrophysics Data System (ADS)

    Szopa, C.; Cernogora, G.; Boufendi, L.; Correia, J. J.; Coll, P.

    2003-04-01

    Titan s atmosphere contains aerosols issued from the organic chemistry induced by the photochemistry of N2 and CH4, the major gaseous atmospheric compounds. These organic aerosols are important as they : i) have a significant influence on the properties of the atmosphere, linked to their optical properties; ii) represent the best known example of transition from the gaseous to the solid phase by chemistry; iii) represent the most complex organics produced in Titan s atmosphere, making them particularly interesting from an exo/astrobiological point of view. However, few direct information are available about them, and their processes of formation and growth are not well understood. In order to bring answers to these questions, we developed a new type of laboratory simulation which is dedicated to better understand the physico-chemical processes involved in the formation and growth of the aerosols. The main originality of this experiment (named PAMPRE) comes from its ability to produce aerosols in volume, as they are maintained in levitation thanks to an electric force compensating gravity, whereas the other similar experiments produce tholins on the reactors walls. Thus, one should produce analogs of Titan s aerosols within representative conditions. Moreover, beyond the ex-situ analyses generally led to characterize the aerosols properties with conventional techniques (MEB, GC-MS), the experimental set-up allows to operate in situ studies of the reactive plasma by UV-vis spectroscopy, in order to deduce the electron energy distribution function which have to be compared with the sun spectrum. Beyond the characterization of the aerosols properties and formation, this experiment will also provide information and materials that will be used to operate the calibrations of the Aerosol and Collector Pyrolyser and Gas Chromatograph-Mass Spectrometer experiments of the Cassini-Huygens mission, and to develop the ICAPS-IMPF facility which should be present in the ISS within

  2. Comparison of Asian aerosol's radiative effect in Seoul and Gosan, Korea

    NASA Astrophysics Data System (ADS)

    Yoon, S.; Lee, S.; Choi, I.

    2007-05-01

    Seasonal variations of aerosol optical properties as well as their direct radiative effects were investigated using the ground-based aerosol measurements and an optical model calculation in Seoul, a mega city, and Gosan, a background rural island, Korea. From the yearly AERONET dataset, our analysis of seasonal and monthly cycle of aerosol optical depth (AOD) shows that AODs in Seoul are higher than those in Gosan because of the higher concentrations of water soluble ions in Seoul. Especially, seasonal AOD differences of both sites becomes maximum in Summer due to the synoptic meteorological patterns and hygroscopic growth of anthropogenic aerosols. OPAC (Optical Properties of Aerosol and Clouds) model and Fu-Liou RTM (Radiative Transfer Model) were employed for the evaluation of aerosol direct radiative forcing (ADRF) at surface and top of the atmosphere (TOA). A method of determining the values of aerosol optical properties as input parameters was utilized for the ADRF calculation from the AERONET dataset. In each season, the mean ADRF in Seoul turned out to be larger than that of Gosan. The ADRF in Gosan from RTM calculation was compared with the ground-based radiation measurements during the ACE-Asia IOP in 2001 and the ABC-EAREX2005 IOP in 2005. In addition, ADRF contributions by chemical compositions were compared in this study between Seoul and Gosan.

  3. Evaluation of aerosol indirect radiative effects on climate in the EMAC model

    NASA Astrophysics Data System (ADS)

    Chang, Dong Yeong; Tost, Holger; Steil, Benedikt; Lelieveld, Jos

    2013-04-01

    Anthropogenic aerosol particles directly and indirectly influence cloud properties and the Earth's radiative energy budget. Several studies have estimated the effects on climate using global circulation models (GCMs), indicating large differences between different models and large uncertainty ranges. These are mostly attributed to different cloud microphysical process parameterizations and uncertainties in the representation of aerosols. Without detailed cloud microphysical processes, using empirical relations between aerosol number or mass and cloud droplet number potentially even large discrepancies may arise. In the present study, a mechanistic aerosol activation scheme, based on double moment cloud microphysics, is used to compute aerosol indirect radiative and cloud effects in the EMAC model. Aerosol activation is linked to the cloud droplet nucleation processes in warm clouds, accounting for the number, size, and chemical composition of particles under ambient meteorological conditions. This approach uses a combination of empirical and semi-empirical parameters to represent aerosol water uptake and hygroscopic growth into cloud droplets. To evaluate the performance of our approach satellite datasets are used; for example, total cloud fraction from MODIS data and cloud radiative forcing at the top of atmosphere from CERES EBAF data.

  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. Effects of relative humidity on aerosol light scattering: results from different European sites

    NASA Astrophysics Data System (ADS)

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

    2013-04-01

    The effect of aerosol water uptake on the aerosol particle light scattering coefficient (σsp) is described in this study by comparing measurements from five European sites: the Jungfraujoch, located in the Swiss Alps at 3580 m a.s.l., Ny-Ålesund, located on Spitsbergen in the Arctic, Mace Head, a coastal site in Ireland, Cabauw, a rural site in the Netherlands and Melpitz, a regional background site in Eastern Germany. These sites were selected according to the aerosol type usually encountered at that location. The scattering enhancement factor f(RH,λ) is the key parameter to describe the effect of water uptake on the particle light scattering. It is defined as the σsp(RH) at a certain relative humidity (RH) and wavelength λ divided by its dry value. f(RH) largely varied at the five sites starting from very low values of f(RH = 85%,λ = 550 nm) around 1.28 for mineral dust to 3.41 for Arctic aerosol. Hysteresis behavior was observed at all sites except at the Jungfraujoch due to the absence of sea salt. Closure studies and Mie simulations showed that both size and chemical composition determine the magnitude of f(RH). Both parameters are also needed to successfully predict f(RH). Finally, the measurement results were compared to the widely used aerosol model OPAC (Hess et al., 1998). Significant discrepancies were seen especially at intermediate RH ranges, which were mainly attributed to inappropriate implemented hygroscopic growth within OPAC. Replacement of the hygroscopic growth with recent literature values showed a clear improvement of the OPAC model.

  6. Effects of relative humidity on aerosol light scattering: results from different European sites

    NASA Astrophysics Data System (ADS)

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

    2013-11-01

    The effect of aerosol water uptake on the aerosol particle light scattering coefficient (σsp) is described in this study by comparing measurements from five European sites: the Jungfraujoch, located in the Swiss Alps at 3580 m a.s.l.; Ny-Ålesund, located on Spitsbergen in the Arctic; Mace Head, a coastal site in Ireland; Cabauw, a rural site in the Netherlands; and Melpitz, a regional background site in Eastern Germany. These sites were selected according to the aerosol type usually encountered at that location. The scattering enhancement factor f(RH, λ) is the key parameter to describe the effect of water uptake on the particle light scattering. It is defined as the σsp(RH) at a certain relative humidity (RH) and wavelength λ divided by its dry value. f(RH) at the five sites varied widely, starting at very low values of f(RH = 85%, λ = 550 nm) around 1.28 for mineral dust, and reaching up to 3.41 for Arctic aerosol. Hysteresis behavior was observed at all sites except at the Jungfraujoch (due to the absence of sea salt). Closure studies and Mie simulations showed that both size and chemical composition determine the magnitude of f(RH). Both parameters are also needed to successfully predict f(RH). Finally, the measurement results were compared to the widely used aerosol model, OPAC (Hess et al., 1998). Significant discrepancies were seen, especially at intermediate RH ranges; these were mainly attributed to inappropriate implementation of hygroscopic growth in the OPAC model. Replacement of the hygroscopic growth with values from the recent literature resulted in a clear improvement of the OPAC model.

  7. Phase, composition and growth mechanism for secondary organic aerosol from the ozonolysis of α-cedrene

    NASA Astrophysics Data System (ADS)

    Zhao, Y.; Wingen, L. M.; Perraud, V.; Finlayson-Pitts, B. J.

    2015-12-01

    Sesquiterpenes are an important class of biogenic volatile organic compounds (BVOCs) and have a high secondary organic aerosol (SOA) forming potential. However, SOA formation from sesquiterpene oxidation has received less attention compared to other BVOCs such as monoterpenes, and the underlying mechanisms remain poorly understood. In this work, we present a comprehensive experimental investigation of the ozonolysis of α-cedrene both in a glass flow reactor (27-44 s reaction times) and in static Teflon chambers (30-60 min reaction times). The SOA was collected by impaction or filters, followed by analysis using attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) and electrospray ionization mass spectrometry (ESI-MS), or measured on line using direct analysis in real time (DART-MS) and aerosol mass spectrometry (AMS). The slow evaporation of 2-ethylhexyl nitrate that was incorporated into the SOA during its formation and growth gives an estimated diffusion coefficient of 3 × 10-15 cm2 s-1 and shows that SOA is a highly viscous semi-solid. Possible structures of four newly observed low molecular weight (MW ≤ 300 Da) reaction products with higher oxygen content than those previously reported were identified. High molecular weight (HMW) products formed in the early stages of the oxidation have structures consistent with aldol condensation products, peroxyhemiacetals, and esters. The size-dependent distributions of HMW products in the SOA, as well as the effects of stabilized Criegee intermediate (SCI) scavengers on HMW products and particle formation, confirm that HMW products and reactions of Criegee intermediates play a crucial role in early stages of particle formation. Our studies provide new insights into mechanisms of SOA formation and growth in α-cedrene ozonolysis and the important role of sesquiterpenes in new particle formation as suggested by field measurements.

  8. Phase, composition, and growth mechanism for secondary organic aerosol from the ozonolysis of α-cedrene

    NASA Astrophysics Data System (ADS)

    Zhao, Yue; Wingen, Lisa M.; Perraud, Véronique; Finlayson-Pitts, Barbara J.

    2016-03-01

    Sesquiterpenes are an important class of biogenic volatile organic compounds (BVOCs) and have a high secondary organic aerosol (SOA) forming potential. However, SOA formation from sesquiterpene oxidation has received less attention compared to other BVOCs such as monoterpenes, and the underlying mechanisms remain poorly understood. In this work, we present a comprehensive experimental investigation of the ozonolysis of α-cedrene both in a glass flow reactor (27-44 s reaction times) and in static Teflon chambers (30-60 min reaction times). The SOA was collected by impaction or filters, followed by analysis using attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy and electrospray ionization mass spectrometry (ESI-MS), or measured online using direct analysis in real-time mass spectrometry (DART-MS) and aerosol mass spectrometry (AMS). The slow evaporation of 2-ethylhexyl nitrate that was incorporated into the SOA during its formation and growth gives an estimated diffusion coefficient of 3 × 10-15 cm2 s-1 and shows that SOA is a highly viscous semisolid. Possible structures of four newly observed low molecular weight (MW ≤ 300 Da) reaction products with higher oxygen content than those previously reported were identified. High molecular weight (HMW) products formed in the early stages of the oxidation have structures consistent with aldol condensation products, peroxyhemiacetals, and esters. The size-dependent distributions of HMW products in the SOA, as well as the effects of stabilized Criegee intermediate (SCI) scavengers on HMW products and particle formation, confirm that HMW products and reactions of SCI play a crucial role in early stages of particle formation. Our studies provide new insights into mechanisms of SOA formation and growth in α-cedrene ozonolysis and the important role of sesquiterpenes in new particle formation as suggested by field measurements.

  9. Aerosol-CFD modelling of ultrafine and black carbon particle emission, dilution, and growth near roadways

    NASA Astrophysics Data System (ADS)

    Huang, L.; Gong, S. L.; Gordon, M.; Liggio, J.; Staebler, R. M.; Stroud, C. A.; Lu, G.; Mihele, C.; Brook, J. R.; Jia, C. Q.

    2014-05-01

    Many studies have shown that on-road vehicle emissions are the dominant source of ultrafine particles (UFP; diameter < 100 nm) in urban areas and near-roadway environments. In order to advance our knowledge on the complex interactions and competition among atmospheric dilution, dispersion and dynamics of UFPs, an aerosol dynamics-CFD coupled model is developed and validated against field measurements. A unique approach of applying periodic boundary conditions is proposed to model pollutant dispersion and dynamics in one unified domain from the tailpipe level to the ambient near-road environment. This approach significantly reduces the size of the computational domain, and therefore, allows fast simulation of multiple scenarios. The model is validated against measured turbulent kinetic energy (TKE) and pollution gradients near a major highway. Through a model sensitivity analysis, the relative importance of individual aerosol dynamical processes on the total particle number concentration (N) and particle number-size distribution (PSD) near a highway is investigated. The results demonstrate that (1) coagulation has a negligible effect on N and particle growth, (2) binary homogeneous nucleation (BHN) of H2SO4-H2O is likely responsible for elevated N closest to the road, (3) N and particle growth are very sensitive to the condensation of semi-volatile organics (SVOCs), particle dry deposition, and the interaction between these processes. The results also indicate that, without the proper treatment of atmospheric boundary layer (i.e. its wind profile and turbulence quantities), the nucleation rate would be underestimated by a factor of 5 in the vehicle wake region due to overestimated mixing. Therefore, introducing ABL conditions to activity-based emission models may potentially improve their performance in estimating UFP traffic emissions.

  10. Characterization of marine boundary layer aerosol from North Atlantic and European sources: Physical and chemical properties and climate forcing parameters

    NASA Astrophysics Data System (ADS)

    Dusek, Ulrike

    This thesis focuses on aerosol properties measured in Southwestern Portugal during the second Aerosol Characterization Experiment. Fundamental aerosol physical properties such as particle size distribution and hygroscopic properties are related to possible sources and aerosol transformation processes. From these fundamental properties we derive aerosol properties that are important for aerosol forcing of climate. First, a new method for calculating CCN spectra is proposed in this work and tested using sensitivity studies and comparisons to direct measurements. The measured and calculated CCN spectra differ on average by 30%, which at small supersaturations is similar to the measurement uncertainties. Second, aerosol number to volume ratios (R) are calculated and the fact that values of R are relatively constrained is explained based on observed correlations between size distribution parameters. Third, a simple parameterization of the humidity dependence of the submicron aerosol scattering coefficient has been derived, depending only on a volume weighted average diameter growth factor and the volume mean diameter of the dry size distribution. One set of empirical parameters can be used to parameterize all aerosol types characterized during the ACE-2 measurement period. Aerosol physical properties and climate forcing parameters in the North-East Atlantic Ocean were clearly affected by pollution outbreaks from Europe. The submicron particle volume increased by a factor of 5 in polluted conditions, the light scattering coefficient of dry particles increased on average by a factor of up to 10, CCN concentrations at supersaturations of 0.2% increased by a factor of 3--5. The aerosol fundamental properties vary often strongly with air mass history, but also show short-term variability that often has a characteristic diurnal scale. The number concentration of fine particles below 50nm and the particle hygroscopic growth factors are mostly dominated by diurnal processes

  11. The effect of water on gas-particle partitioning of secondary organic aerosol. Part I: α-pinene/ozone system

    NASA Astrophysics Data System (ADS)

    Cocker, David R., III; Clegg, Simon L.; Flagan, Richard C.; Seinfeld, John H.

    The effect of relative humidity (RH) on aerosol formation by the semi-volatile oxidation products of the α-pinene/O 3 system has been comprehensively studied. Experiments were performed in the presence of ammonium sulfate (aqueous, dry), ammonium bisulfate seed (aqueous, dry), and aqueous calcium chloride seed aerosols to ascertain their effect on the partitioning of the oxidation products. The yield of organic aerosol varies little with RH, and is not affected by the presence of dry inorganic salt aerosols. Aqueous salt aerosols reduce the yield of organic aerosol compared to that under seed-free or dry seed conditions. The degree of reduction is electrolyte dependent, with aqueous ammonium sulfate leading to the largest reduction and aqueous calcium chloride the smallest. Hygroscopic growth of the organic aerosol from <2% to 85% RH was also monitored, and could be satisfactorily represented as the sum of the individual contributions of the organic and inorganic fractions. The implications of the growth factor measurements for concentration/activity relationships of the condensed phase organic material (assuming a liquid solution) was explored. The formation of the organic aerosol was investigated using a simple two component model, and also one including the 12 product compounds identified in a previous study. The experimental results for <2% and 50% RH (without salt seed aerosols) could be satisfactorily predicted. However, the aqueous salt seed aerosols are predicted to increase the overall yield due to the dissolution of the organic compounds into the water associated with the seed aerosol—the opposite effect to that observed. The implications of two distinct phases existing the aerosol phase were investigated.

  12. DEVELOPMENT OF SURROGATE LUNG SYSTEMS WITH CONTROLLED THERMODYNAMIC ENVIRONMENTS TO STUDY HYGROSCOPIC PARTICLES, AIR POLLUTANTS AND PHARMACOLOGIC DRUGS

    EPA Science Inventory

    The objective of this text is to demonstrate advantages of interdisciplinary efforts,specifically, applications of engineering technology to health effects issues. he work describes the development of surrogate systems of the human lung for use in studies of hygroscopic growth ki...

  13. Hygroscopicity of nanoparticles produced from homogeneous nucleation in the CLOUD experiments

    NASA Astrophysics Data System (ADS)

    Kim, J.; Ahlm, L.; Yli-Juuti, T.; Lawler, M.; Keskinen, H.; Tröstl, J.; Schobesberger, S.; Duplissy, J.; Amorim, A.; Bianchi, F.; Donahue, N. M.; Flagan, R. C.; Hakala, J.; Heinritzi, M.; Jokinen, T.; Kürten, A.; Laaksonen, A.; Lehtipalo, K.; Miettinen, P.; Petäjä, T.; Rissanen, M. P.; Rondo, L.; Sengupta, K.; Simon, M.; Tomé, A.; Williamson, C.; Wimmer, D.; Winkler, P. M.; Ehrhart, S.; Ye, P.; Kirkby, J.; Curtius, J.; Kulmala, M.; Lehtinen, K. E. J.; Smith, J. N.; Riipinen, I.; Virtanen, A.

    2015-07-01

    Sulfuric acid, amines and oxidized organics have been found to be important compounds in the nucleation and initial growth of atmospheric particles. Because of the challenges involved in determining the chemical composition of objects with very small mass, however, the properties of the freshly nucleated particles and the detailed pathways of their formation processes are still not clear. In this study, we focus on a challenging size range, i.e. particles that have grown to diameters of 10 and 15 nm following nucleation, and measure their water uptake. Water uptake constrains their chemical composition. We use a nanometer-hygroscopicity tandem differential mobility analyzer (nano-HTDMA) at subsaturated conditions (ca. 90 % relative humidity at 293 K) to measure the hygroscopicity of particles during the seventh Cosmics Leaving OUtdoor Droplets (CLOUD7) experiments performed at CERN in 2012. In CLOUD7, the hygroscopicity of nucleated nanoparticles was measured in the presence of sulfuric acid, sulfuric acid-dimethylamine, and sulfuric acid-organics derived from α-pinene oxidation. The hygroscopicity parameter κ decreased with increasing particle size indicating decreasing acidity of particles. No clear effect of the sulfuric acid monomer concentrations on the hygroscopicities of 10 nm particles produced from sulfuric acid and dimethylamine was observed, whereas the hygroscopicity of 15 nm particles sharply decreased with decreasing sulfuric acid monomer concentrations. In particular, when the concentrations of sulfuric acid was 5.1 × 106 molecules cm-3 in the gas phase, and the dimethylamine mixing ratio was 11.8 ppt, the measured κ of 15 nm particles was 0.31 ± 0.01 close to the value reported for dimethylamine sulfate (DMAS) (κDMAS ~ 0.28). Furthermore, the difference in κ between sulfuric acid and sulfuric acid-dimethylamine experiments increased with increasing particle size. The κ values of particles in the presence of sulfuric acid and organics were

  14. A multi-model evaluation of aerosols over South Asia: common problems and possible causes

    NASA Astrophysics Data System (ADS)

    Pan, X.; Chin, M.; Gautam, R.; Bian, H.; Kim, D.; Colarco, P. R.; Diehl, T. L.; Takemura, T.; Pozzoli, L.; Tsigaridis, K.; Bauer, S.; Bellouin, N.

    2015-05-01

    Atmospheric pollution over South Asia attracts special attention due to its effects on regional climate, water cycle and human health. These effects are potentially growing owing to rising trends of anthropogenic aerosol emissions. In this study, the spatio-temporal aerosol distributions over South Asia from seven global aerosol models are evaluated against aerosol retrievals from NASA satellite sensors and ground-based measurements for the period of 2000-2007. Overall, substantial underestimations of aerosol loading over South Asia are found systematically in most model simulations. Averaged over the entire South Asia, the annual mean aerosol optical depth (AOD) is underestimated by a range 15 to 44% across models compared to MISR (Multi-angle Imaging SpectroRadiometer), which is the lowest bound among various satellite AOD retrievals (from MISR, SeaWiFS (Sea-Viewing Wide Field-of-View Sensor), MODIS (Moderate Resolution Imaging Spectroradiometer) Aqua and Terra). In particular during the post-monsoon and wintertime periods (i.e., October-January), when agricultural waste burning and anthropogenic emissions dominate, models fail to capture AOD and aerosol absorption optical depth (AAOD) over the Indo-Gangetic Plain (IGP) compared to ground-based Aerosol Robotic Network (AERONET) sunphotometer measurements. The underestimations of aerosol loading in models generally occur in the lower troposphere (below 2 km) based on the comparisons of aerosol extinction profiles calculated by the models with those from Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) data. Furthermore, surface concentrations of all aerosol components (sulfate, nitrate, organic aerosol (OA) and black carbon (BC)) from the models are found much lower than in situ measurements in winter. Several possible causes for these common problems of underestimating aerosols in models during the post-monsoon and wintertime periods are identified: the aerosol hygroscopic growth and formation of

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

    NASA Astrophysics Data System (ADS)

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

    2016-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-08-01

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

  17. 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.

  18. Study of Hygroscopic Properties of Aminium Sulfate Particles Using Micro-Raman Spectroscopy

    NASA Astrophysics Data System (ADS)

    Chu, Y.; Sauerwein, M.; Chan, C. K.

    2014-12-01

    As one of the organic nitrogen species, amines are alkaline compounds ubiquitously detected in the atmosphere. Amines have been found to have the potential to enhance atmospheric new particle formation via forming aminium sulfate salts as much as 1000-fold when compared with ammonia, albeit at relatively low atmospheric contents (Almeida et al., 2013). Hygroscopicity of aminium sulfate particles can affect their cloud condensation nuclei (CCN) activity, light scattering or absorption and reactivity in the atmosphere. However, aerosol thermodynamic models such as Extended Aerosol Thermodynamics Model (E-AIM) assume that aminium ions behave similarly to ammonium ions, thus resulting in inaccuracy in predictinghygroscopicity of such compounds. In this study, Micro-Raman spectroscopy was applied to investigate the hygroscopicity of mono-methylaminium sulfate (MMAS), di-methylaminium sulfate (DMAS), tri-methylaminium sulfate (TMAS) and mono-ethylaminium sulfate (MEAS) particles. Since amine can evaporate from stock solutions, Ion Chromatography was used to determine aminium-to-sulfate ion molar ratio (A/S) of studied particles. Results were compared with literature data (Clegg et al., 2013). Due to amine evaporation upon mixing, A/S of stock solutions for particle generation can be below 2.0. In fact, initial A/S were 1.59, 1.91, 1.33 and 2.00 of MMAS, DMAS, TMAS and MEAS particles respectively. Ultimately A/S decreased to 1.5 and 1.0 for DMAS and TMAS, suggesting di-methylamine (DMA) and tri-methylamine (TMA) evaporated from corresponding particles. A/S of MMAS and MEAS kept relatively constant during the relative humidity (RH) cycle in hygroscopic measurements. Unlike (NH4)2SO4, all studied aminium sulfate particles can take up water at low RH. MMAS and MEAS particles underwent phase transition at around 45% and 20% RH respectively, while particles of other aminium sulfates showed continuous hygroscopic trends. References: Almeida, J. et al., 2013. Nature 502, 359

  19. Simulation studies on shape and growth kinetics for fractal aggregates in aerosol and colloidal systems

    NASA Astrophysics Data System (ADS)

    Heinson, William Raymond

    The aim of this work is to explore, using computational techniques that simulate the motion and subsequent aggregation of particles in aerosol and colloidal systems, many common but not well studied systems that form fractal clusters. Primarily the focus is on cluster shape and growth kinetics. The structure of clusters made under diffusion limited cluster-cluster aggregation (DLCA) is looked at. More specifically, the shape anisotropy is found to have an inverse relationship on the scaling prefactor k0 and have no effect on the fractal dimension Df . An analytical model that predicts the shape and fractal dimension of diffusion limited cluster-cluster aggregates is tested and successfully predicts cluster shape and dimensionality. Growth kinetics of cluster-cluster aggregation in the free molecular regime where the system starts with ballistic motion and then transitions to diffusive motion as the aggregates grow in size is studied. It is shown that the kinetic exponent will crossover from the ballistic to the diffusional values and the onset of this crossover is predicted by when the nearest neighbor Knudsen number reaches unity. Simulations were carried out for a system in which molten particles coalesce into spheres, then cool till coalescing stops and finally the polydispersed monomers stick at point contacts to form fractal clusters. The kinetic exponent and overall cluster structure for these aggregates was found to be in agreement with DLCA that started with monodispersed monomers. Colloidal aggregation in the presence of shear was studied in detail. Study of a colloidal system characterized a by short-range attractive potential showed that weak shear enhanced the aggregation process. Strong shear led to fragmentation and subsequent nucleation as cluster growth rebounded after an induction time.

  20. Inorganic aerosol formation and growth in the Earth's lower and upper atmosphere

    NASA Astrophysics Data System (ADS)

    Saunders, R. W.; Plane, J. M. C.

    2006-12-01

    This chapter describes the photo-chemical production of aerosol particles in two very different regions of the atmosphere: iodine oxide particles in the marine boundary layer (MBL), and meteoric smoke particles that form in the upper mesosphere from the ablation of interplanetary dust. These two systems are surprisingly analogous the source of the condensable inorganic vapours is external to the atmosphere, being injected into the atmosphere from the ocean or from space and the particles are formed by homogeneous nucleation. The purpose of the chapter is to describe a laboratory and modelling study to understand at a fundamental level how the nucleation and growth of the particles occurs. Iodine oxide particles were produced from the photo-oxidation of gaseous I{2} with O{3}, which is most likely the primary photo-chemical route to produce the bursts of new particles observed in the MBL at seaweed-rich coastal locations. The captured particles were observed to be fractal-like (i.e., with open or non-compact structures), and to be composed of the stable oxide I{2}O{5}. Meteoric smoke analogues of iron oxide, silicon oxide, and iron silicate composition were similarly formed from the photo-oxidation of iron- and silicon-containing gas-phase precursors in the presence of O{3}. Imaging of the iron-containing particles showed them to be extended, fractal aggregates. For each system, models were developed to elucidate the growth kinetics of the particles and to characterise them in terms of standard fractal parameters. I{2}O{5} particles were found to have a fractal dimension (Df) value of 2.5 at long growth times, consistent with a particle-cluster diffusion-limited aggregation (DLA) mechanism, whereas smoke analogues had lower Df values (1.75) which appear to result from a magnetic aggregation process.

  1. Radiative impact of atmospheric aerosols and clouds

    NASA Astrophysics Data System (ADS)

    Wong, Jeff

    1998-11-01

    The effect of aerosols and clouds on Earth's shortwave radiation budget is studied in this thesis. An expression for the global annual mean radiative forcing due to sulfate aerosols is extended for absorbing aerosols using a two-stream approximation. This expression depends on the backscattering fraction of the aerosol which varies with the effective radius of the aerosol size distribution. This variation leads to a factor of 2.0 variation in the radiative forcing of slightly absorbing aerosols. Water vapor condenses onto hygroscopic aerosols which results in a change in size and a change in the concentration of the chemical components of the aerosol. The original Köhler equation accurately describes the equilibrium size of a hygroscopic aerosol. Use of the modified Köhler equation leads to errors due to its thermodynamically inconsistent nature. On a global annual average, the direct radiative forcing of hygroscopic sulfate aerosol is -0.69 W m-2. Over highly polluted regions, the local radiative forcing can be as high as -7 W m-2 which is comparable to the forcing due to increased greenhouse gas concentrations. Using a plane-parallel model, an analytical expression is derived for the cloud radiative forcing ratio which is used as a measure of enhanced shortwave radiation absorption of clouds. With this model, high values of this ratio can be achieved by thick clouds with absorptances of approximately 0.3. High values of the ratio can also be obtained with low level clouds if the transmittance of the atmosphere above the cloud is reduced to approximately 0.8. This can be achieved by a high concentration of strongly absorbing aerosols.

  2. Characterizing the Vertical Distribution of Aerosols Over the ARM SGP Site

    SciTech Connect

    Richard Ferrare, Connor Flynn, David Turner

    2009-05-05

    This project focused on: 1) evaluating the performance of the DOE ARM SGP Raman lidar system in measuring profiles of water vapor and aerosols, and 2) the use of the Raman lidar measurements of aerosol and water vapor profiles for assessing the vertical distribution of aerosols and water vapor simulated by global transport models and examining diurnal variability of aerosols and water vapor. The highest aerosol extinction was generally observed close to the surface during the nighttime just prior to sunrise. The high values of aerosol extinction are most likely associated with increased scattering by hygroscopic aerosols, since the corresponding average relative humidity values were above 70%. After sunrise, relative humidity and aerosol extinction below 500 m decreased with the growth in the daytime convective boundary layer. The largest aerosol extinction for altitudes above 1 km occurred during the early afternoon most likely as a result of the increase in relative humidity. The water vapor mixing ratio profiles generally showed smaller variations with altitude between day and night. We also compared simultaneous measurements of relative humidity, aerosol extinction, and aerosol optical thickness derived from the ARM SGP Raman lidar and in situ instruments on board a small aircraft flown routinely over the ARM SGP site. In contrast, the differences between the CARL and IAP aerosol extinction measurements are considerably larger. Aerosol extinction derived from the IAP measurements is, on average, about 30-40% less than values derived from the Raman lidar. The reasons for this difference are not clear, but may be related to the corrections for supermicron scattering and relative humidity that were applied to the IAP data. The investigators on this project helped to set up a major field mission (2003 Aerosol IOP) over the DOE ARM SGP site. One of the goals of the mission was to further evaluate the aerosol and water vapor retrievals from this lidar system

  3. Aircraft- and ground-based assessment of the CCN-AOD relationship and implications on model analysis of ACI and underlying aerosol processes

    NASA Astrophysics Data System (ADS)

    Shinozuka, Y.; Clarke, A. D.; Nenes, A.; Lathem, T. L.; Redemann, J.; Jefferson, A.; Wood, R.

    2014-12-01

    Contrary to common assumptions in satellite-based modeling of aerosol-cloud interactions, ∂logCCN/∂logAOD is less than unity, i.e., the number concentration of cloud condensation nuclei (CCN) less than doubles as aerosol optical depth (AOD) doubles. This can be explained by omnipresent aerosol processes. Condensation, coagulation and cloud processing, for example, generally make particles scatter more light while hardly increasing their number. This paper reports on the relationship in local air masses between CCN concentration, aerosol size distribution and light extinction observed from aircraft and the ground at diverse locations. The CCN-to-local-extinction relationship, when averaged over ~1 km distance and sorted by the wavelength dependence of extinction, varies approximately by a factor of 2, reflecting the variability in aerosol intensive properties. This, together with retrieval uncertainties and the variability in aerosol spatio-temporal distribution and hygroscopic growth, challenges satellite-based CCN estimates. However, the large differences in estimated CCN may correspond to a considerably lower uncertainty in cloud drop number concentration (CDNC), given the sublinear response of CDNC to CCN. Overall, our findings from airborne and ground-based observations call for model-based reexamination of aerosol-cloud interactions and underlying aerosol processes.

  4. Aerosol characteristics in Phimai, Thailand determined by continuous observation with a polarization sensitive Mie-Raman lidar and a sky radiometer

    NASA Astrophysics Data System (ADS)

    Sugimoto, Nobuo; Shimizu, Atsushi; Nishizawa, Tomoaki; Matsui, Ichiro; Jin, Yoshitaka; Khatri, Pradeep; Irie, Hitoshi; Takamura, Tamio; Aoki, Kazuma; Thana, Boossarasiri

    2015-06-01

    Distributions and optical characteristics of aerosols were continuously observed with a polarization-sensitive (532 nm), Mie-scattering (532 and 1064 nm) and Raman-scattering (607 nm) lidar and a sky radiometer in Phimai, Thailand. Polarization lidar measurements indicated that high concentration plumes of spherical aerosols considered as biomass burning smoke were often observed in the dry season. Plumes of non-spherical aerosols considered as long-range transported soil dust from Africa, the Middle East, or Northeast Asia were occasionally observed. Furthermore, low-concentration non-spherical aerosols were almost always observed in the atmospheric mixing layer. Extinction coefficient profiles of spherical aerosols and non-spherical dust exhibited different diurnal variations, and spherical aerosols including smoke were distributed in higher altitudes in the mixing layer and residual layer. The difference can be explained by hygroscopic growth of smoke particles and buoyancy of the smoke. Analysis of seasonal variations of optical properties derived from the Raman lidar and the sky radiometer confirmed that the lidar ratio, aerosol optical depth, and Angstrom exponent were higher in the dry season (October-May) and lower in the wet season (June-September). The single scattering albedo was lower in the dry season. These seasonal variations are explained by frequent biomass burning in the dry season consistent with previous studies in Southeast Asian region. At the same time, the present work confirmed that soil dust was a major aerosol component in Phimai, Thailand.

  5. 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).

  6. Production, growth and properties of ultrafine atmospheric aerosol particles in an urban environment

    NASA Astrophysics Data System (ADS)

    Salma, I.; Borsós, T.; Weidinger, T.; Aalto, P.; Hussein, T.; Dal Maso, M.; Kulmala, M.

    2010-06-01

    Number concentrations of atmospheric aerosol particles were measured by a flow-switching type differential mobility particle sizer in an electrical mobility diameter range of 6-1000 nm in 30 channels near central Budapest with a time resolution of 10 min continuously from 3 November 2008 to 2 November 2009. Daily median number concentrations of particles varied from 3.8×103 to 29×103 cm-3 with a yearly median of 11.8×103 cm-3. Contribution of ultrafine particles to the total particle number ranged from 58 to 92% with a mean ratio and standard deviation of (79±6)%. Daily average number concentrations in various size fractions and contribution of ultrafine particles to the total particle number showed no seasonal dependency. Monthly mean number size distributions were similar to each other. Overall mean for the number median mobility diameter of the Aitken and accumulation modes were 26 and 93 nm, respectively, which are substantially smaller than for rural or background environments. The Aitken and accumulation modes contributed similarly to the total particle number concentrations at the actual measurement location. Median diameters of the Aitken and accumulation modes were shifted to larger values before nucleation started and over the growth process, which can be related to the presence of aged aerosol under the conditions that favour nucleation and growth. Particle concentrations were usually increased substantially after nucleations. Overall mean and standard deviation of the nucleation mode number concentrations were (10.4±2.8)×103 cm-3. Mean ratio and standard deviation of the nucleation mode number concentration to the total particle number concentration that was averaged for two hours just before the formation was detected was 2.3±1.1. Nucleation unambiguously occurred on 83 days, which represent 27% of all relevant days. Its frequency showed a remarkable seasonal variation with a minimum of 7.3% in winter and a maximum of 44% in spring. Formation

  7. Instrument calibration and aerosol optical depth validation of the China Aerosol Remote Sensing Network

    NASA Astrophysics Data System (ADS)

    Che, Huizheng; Zhang, Xiaoye; Chen, Hongbin; Damiri, Bahaiddin; Goloub, Philippe; Li, Zhengqiang; Zhang, Xiaochun; Wei, Yao; Zhou, Huaigang; Dong, Fan; Li, Deping; Zhou, Tianming

    2009-02-01

    This paper introduced the calibration of the CE-318 sunphotometer of the China Aerosol Remote Sensing Network (CARSNET) and the validation of aerosol optical depth (AOD) by AOD module of ASTPWin software compared with the simultaneous measurements of the Aerosol Robotic Network (AERONET)/Photométrie pour le Traitement Opérationnel de Normalization Satellitaire (PHOTONS) and PREDE skyradiometer. The results show that the CARSNET AOD measurements have the same accuracy as the AERONET/PHOTONS. On the basis of a comparison between CARSNET and AERONET, the AODs from CARSNET at 1020, 870, 670, and 440 nm are about 0.03, 0.01, 0.01, and 0.01 larger than those from AERONET, respectively. The aerosol optical properties over Beijing acquired through the CE-318 sunphotometers of one AERONET/PHOTONS site and two CARSNET sites were analyzed on the basis of 4-year measurements. It was obvious that the AOD of the Shangdianzi site (rural site) was lower than that of the two urban sites (the Institute of Atmospheric Physics (IAP) site (north urban site) and the Beijing Meteorological Observatory (BJO) site (south urban site)). The AOD of BJO was about 0.05, 0.04, 0.05, and 0.06 larger than that of IAP at 1020, 870, 670, and 440 nm, respectively, indicating that there is more local pollution in the south part of Beijing. The highest AOD was found in summer because of the stagnation planetary boundary layer and transport of pollutants from large pollution centers south of Beijing. The high temperature and relative humidity in summer also favor the production of aerosol precursor and the hygroscopic growth of the existing particles locally, which results in high AOD. In contrast, the lowest AOD at the two urban sites and one rural site in Beijing occurred in winter as the frequent cold air masses help pollutants diffuse easily.

  8. Insulin-like growth factor-I aerosol formulations for pulmonary delivery.

    PubMed

    Germershaus, Oliver; Schultz, Isabel; Lühmann, Tessa; Beck-Broichsitter, Moritz; Högger, Petra; Meinel, Lorenz

    2013-09-01

    Injectable insulin-like growth factor-1 (IGF-I) is therapeutically deployed for severe IGF-I deficiency and clinically explored for various other indications such as muscle wasting disease. In the present study, liquid IGF-I formulations for pulmonal application were screened with regard to buffer type (acetate, citrate, histidine, and succinate), sodium chloride concentration (50-150 mM), and pH value (4.5-6.5). Methionine 59 oxidation (Met(o)) was observed in acetate buffer along with reducible dimer and trimer formation at low pH. Oxidation correlated with formation of covalent, reducible aggregates, and complete loss of potency was observed for severely aggregated samples. Bioactivity was partly retained in cases where complete oxidation but limited aggregation was found. In contrast, IGF-I integrity was preserved in histidine buffer during accelerated stability. After delivery from air-jet or vibrating-mesh nebulizers, limited Met(o) formation and no aggregation was observed. Nebulization performance regarding aerosol output rate, mass median aerodynamic diameter, and fine particle fraction for liquid IGF-I formulation was comparable to 0.9% sodium chloride reference, confirming the suitability for pulmonal application. In conclusion, different IGF-I liquid formulations were studied and compositions were identified maintaining bioactivity and chemical stability throughout storage at accelerated conditions for up to 4 months as well as compatibility with air-jet and vibrating-mesh nebulizers. PMID:23958318

  9. Ambient measurements of chemical and physical properties of organic aerosols: Insights into formation, growth, and heterogeneous chemistry

    NASA Astrophysics Data System (ADS)

    Ziemba, Luke D.

    Organic aerosols are a ubiquitous component of the troposphere, from heavily polluted cities to the remote Arctic. In Chapters II, III, and V of this dissertation, the formation of organic aerosol through observations of ambient size distributions is addressed. Chapter IV presents a new pathway for the formation of nitrous acid (HONO) in the urban atmosphere. In Chapter II, the size-resolved chemical composition of sub-micron aerosol was measured at a suburban forested site in North Carolina. Two events were identified in which particle growth, presumably by gas-to-particle conversion, was dominated by accumulation of organic aerosol mass. Growth rates between 1.2 nm hr-1 and 4.9 nm hr-1 were observed. Using a mass-spectral deconvolution method coupled with linear regression analysis, the sub-micron organic aerosol mass observed during the campaign, and during events, was determined to have been influenced by both local and regional secondary processes with only a minor influence from combustion sources. In Chapter III, the chemical characteristics of sub-10-micron aerosol were explored as a function of ambient particle size at a coastal and inland site in New England. Average organic carbon (OC) concentrations of 4.9 microg C m-3 and 3.4 microg C m-3 were observed at the coastal site at the Isles of Shoals (IOS) and at the slightly inland site at Thompson Farm (TF), respectively. An average of 84 and 72% of OC was found to be water-soluble at IOS and TF, respectively. Size distributions indicate that the formation of dicarboxylic acids, especially oxalic acid, is driven by aqueous-phase reactions. A chemical fingerprint analysis suggests that all water-soluble OC at IOS resembles secondary organic aerosol (SOA), while WSOC at TF appears to result from mixed sources. In Chapter IV, a newly identified formation pathway for nitrous acid (HONO) is presented. HONO is an important precursor to hydroxyl radicals in the troposphere and thus contributes to the oxidative

  10. Parameterization of the Cloud Nucleating Activity of Fresh, Aged, and Internally-Mixed Organic Aerosols

    NASA Astrophysics Data System (ADS)

    Kreidenweis, S.; Petters, M.; Demott, P.; Prenni, A.; Ziemann, P.

    2006-12-01

    Carbonaceous particle types affect global climate, visibility, and human health, but their primary and secondary sources, sinks, and tropospheric lifetimes are highly uncertain. The size and hygroscopicity of particles, and in particular their activity as cloud condensation nuclei (CCN), plays a large role in determining their atmospheric impacts and lifetimes. However, hygroscopicity is difficult to parameterize for many organic species for which no thermodynamic data exist, and for complex, multicomponent aerosols of undefined composition. We propose a simple method to describe the relationship between dry particle diameter and CCN activity using a single hygroscopicity parameter, κ. We derive values of κ from fitting of experimental CCN-activity data from the literature and from recent experiments, including oxidation-aged organic particles and secondary organic aerosols. Values of κ are between 0.5 and 2 for highly-CCN- active salts such as sodium chloride, between 0.01 and 0.5 for slightly to very hygroscopic organic aerosols such as those produced in biomass burning and as secondary organic aerosols, and 0 for nonhygroscopic components. The hygroscopicity of internal mixtures can be calculated as a volume fraction weighted average of the hygroscopicity parameters of the individual species comprising the mixture. Aging of aerosol, understood as changes in hygroscopicity due to condensation of hydrophilic species, coagulation of aerosol populations, or heterogeneous chemical reactions, are described conveniently by changes in κ. Our studies show that oxidative aging that proceeds by addition of functional groups to the CHx carbon backbone leads to only small changes in κ, and thus the process alone is inefficient at rendering small, initially- hydrophobic primary organic particles capable of being scavenged by cloud-drop nucleation. Other processes, such as coagulation and condensation, control the rate of hydrophobic-to-hydrophilic conversion of primary

  11. A multi-model evaluation of aerosols over South Asia: Common problems and possible causes

    NASA Astrophysics Data System (ADS)

    Pan, X.; Chin, M.; Gautam, R.; Bian, H.; Kim, D.; Colarco, P. R.; Diehl, T. L.; Takemura, T.; Pozzoli, L.; Tsigaridis, K.; Bauer, S.; Bellouin, N.

    2014-07-01

    not considered in 4 out of 7 models or significantly lower than observations in other 2 models. Surprisingly, the near-surface relative humidity in these models is found significantly lower than observations in the winter, resulting in suppression of the hygroscopic growth of soluble aerosols and formations of sulfate and nitrate, and thereby underestimation of AOD. During the post-monsoon season, the deficiency of agricultural waste burning emissions in GFED2 biomass burning emission inventory, used by the models, partly contributes to the model underestimation of aerosol loading over South Asia in burning seasons.

  12. Impact of Particle Generation Method on the Apparent Hygroscopicity of Insoluble Mineral Particles

    SciTech Connect

    Sullivan, Ryan; Moore, Meagan J.; Petters, Markus D.; Kreidenweis, Sonia M.; Qafoku, Odeta; Laskin, Alexander; Roberts, Greg C.; Prather, Kimberly A.

    2010-07-28

    Atmospheric mineral dust particles represent a major component of tropospheric aerosol mass and provide a reactive surface for heterogeneous reactions with trace atmospheric gases (Dentener et al. 1996).Heterogeneous processes alter the chemical balance of the atmosphere and also modify the physicochemical properties of mineral dust particles (Bauer et al. 2004). Organic and inorganic vapors can react with or partition to dust particles and alter their chemical composition (Al-Hosney et al. 2005; Laskin et al. 2005a, 2005b; Liu et al. 2008; Sullivan et al. 2007, 2009a; Sullivan and Prather 2007; Usher et al. 2003). Calcite (CaCO3) is one of the most reactive components of mineral dust, readily reacting with acidic gases. The fraction of CaCO3 in total dust mineralogy displays large variations between desert regions and other regions of the world as well as between individual mineral particles (Claquin et al. 1999; Jeong 2008; Laskin et al. 2005b; Sullivan et al. 2007). Through reactions with acidic gases CaCO3 can be converted to soluble hygroscopic products including CaCl2 and Ca(NO3)2, and sparingly soluble, non-hygroscopic products including CaSO4 and CaC2O4 (Krueger et al. 2004; Liu et al. 2008; Sullivan et al. 2009a, 2009b).

  13. Hygroscopic Properties of Internally Mixed Particles Composed of NaCl and Water-Soluble Organic Acids

    SciTech Connect

    Ghorai, Suman; Wang, Bingbing; Tivanski, Alexei V.; Laskin, Alexander

    2014-02-18

    Atmospheric aging of naturally emitted marine aerosol often leads to formation of internally mixed particles composed of sea salts and water soluble organic compounds of anthropogenic origin. Mixing of sea salt and organic components has profound effects on the evolving chemical composition and hygroscopic properties of the resulted particles, which are poorly understood. Here, we have studied chemical composition and hygroscopic properties of laboratory generated NaCl particles mixed with malonic acid (MA) and glutaric acid (GA) at different molar ratios using micro-FTIR spectroscopy and X-ray elemental microanalysis.Hygroscopic properties of inte rnally mixed NaCl and organic acid particles were distinctly different from pure components and varied significantly with the type and amount of organic compound present. Experimental results were in a good agreement with the AIM modeling calculations of gas/liquid/solid partitioning in studied systems. X-ray elemental microanalysis of particles showed that Cl/Na ratio decreased with increasing organic acid component in the particles with MA yielding lower ratios relative to GA. We attribute the depletion of chloride to the formation of Na-malonate and Na-glutarate salts resulted by HCl evaporation from dehydrating particles.

  14. Hygroscopic properties of internally mixed particles composed of NaCl and water-soluble organic acids.

    PubMed

    Ghorai, Suman; Wang, Bingbing; Tivanski, Alexei; Laskin, Alexander

    2014-02-18

    Atmospheric aging of naturally emitted marine aerosol often leads to formation of internally mixed particles composed of sea salts and water-soluble organic compounds of anthropogenic origin. Mixing of sea salt and organic components has profound effects on the evolving chemical composition and hygroscopic properties of the resulted particles, which are poorly understood. Here, we have studied chemical composition and hygroscopic properties of laboratory generated NaCl particles mixed with malonic acid (MA) and glutaric acid (GA) at different molar ratios using micro-FTIR spectroscopy, atomic force microscopy, and X-ray elemental microanalysis. Hygroscopic properties of internally mixed NaCl and organic acid particles were distinctly different from pure components and varied significantly with the type and amount of organic compound present. Experimental results were in a good agreement with the AIM modeling calculations of gas/liquid/solid partitioning in studied systems. X-ray elemental microanalysis of particles showed that Cl/Na ratio decreased with increasing organic acid component in the particles with MA yielding lower ratios relative to GA. We attribute the depletion of chloride to the formation of sodium malonate and sodium glutarate salts resulted by HCl evaporation from dehydrating particles. PMID:24437520

  15. Chemical characterization of submicron aerosol and particle growth events at a national background site (3295 m a.s.l.) on the Tibetan Plateau

    NASA Astrophysics Data System (ADS)

    Du, W.; Sun, Y. L.; Xu, Y. S.; Jiang, Q.; Wang, Q. Q.; Yang, W.; Wang, F.; Bai, Z. P.; Zhao, X. D.; Yang, Y. C.

    2015-09-01

    Atmospheric aerosols exert highly uncertain impacts on radiative forcing and also have detrimental effects on human health. While aerosol particles are widely characterized in megacities in China, aerosol composition, sources and particle growth in rural areas in the Tibetan Plateau remain less understood. Here we present the results from an autumn study that was conducted from 5 September to 15 October 2013 at a national background monitoring station (3295 m a.s.l.) in the Tibetan Plateau. The submicron aerosol composition and particle number size distributions were measured in situ with an Aerodyne Aerosol Chemical Speciation Monitor (ACSM) and a Scanning Mobility Particle Sizer (SMPS). The average mass concentration of submicron aerosol (PM1) is 11.4 μg m-3 (range: 1.0-78.4 μg m-3) for the entire study, which is much lower than observed at urban and rural sites in eastern China. Organics dominated PM1, accounting for 43 % on average, followed by sulfate (28 %) and ammonium (11 %). Positive Matrix Factorization analysis of ACSM organic aerosol (OA) mass spectra identified an oxygenated OA (OOA) and a biomass burning OA (BBOA). The OOA dominated OA composition, accounting for 85 % on average, 17 % of which was inferred from aged BBOA. The BBOA contributed a considerable fraction of OA (15 %) due to the burning of cow dung and straw in September. New particle formation and growth events were frequently observed (80 % of time) throughout the study. The average particle growth rate is 2.0 nm h-1 (range: 0.8-3.2 nm h-1). By linking the evolution of particle number size distribution to aerosol composition, we found an elevated contribution of organics during particle growth periods and also a positive relationship between the growth rate and the fraction of OOA in OA, which potentially indicates an important role of organics in particle growth in the Tibetan Plateau.

  16. Production, growth and properties of ultrafine atmospheric aerosol particles in an urban environment

    NASA Astrophysics Data System (ADS)

    Salma, I.; Borsós, T.; Weidinger, T.; Aalto, P.; Hussein, T.; Dal Maso, M.; Kulmala, M.

    2011-02-01

    Number concentrations of atmospheric aerosol particles were measured by a flow-switching type differential mobility particle sizer in an electrical mobility diameter range of 6-1000 nm in 30 channels near central Budapest with a time resolution of 10 min continuously from 3 November 2008 to 2 November 2009. Daily median number concentrations of particles varied from 3.8 × 103 to 29 ×103 cm-3 with a yearly median of 11.8 × 103 cm-3. Contribution of ultrafine particles to the total particle number ranged from 58 to 92% with a mean ratio and standard deviation of (79 ± 6)%. Typical diurnal variation of the particle number concentration was related to the major emission patterns in cities, new particle formation, sinks of particles and meteorology. Shapes of the monthly mean number size distributions were similar to each other. Overall mean for the number median mobility diameter of the Aitken and accumulation modes were 26 and 93 nm, respectively, which are substantially smaller than for rural or background environments. The Aitken and accumulation modes contributed similarly to the total particle number concentrations at the actual measurement location. New particle formation and growth unambiguously occurred on 83 days, which represent 27% of all relevant days. Hence, new particle formation and growth are not rare phenomena in Budapest. Their frequency showed an apparent seasonal variation with a minimum of 7.3% in winter and a maximum of 44% in spring. New particle formation events were linked to increased gas-phase H2SO4 concentrations. In the studied area, new particle formation is mainly affected by condensation sink and solar radiation. The formation process seems to be not sensitive to SO2, which was present in a yearly median concentration of 6.7 μg m-3. This suggests that the precursor gas was always available in excess. Formation rate of particles with a diameter of 6 nm varied between 1.65 and 12.5 cm-3 s-1 with a mean and standard deviation of (4.2

  17. Final Report: "Collaborative Project. Understanding the Chemical Processes That Affect Growth Rates of Freshly Nucleated Particles"

    SciTech Connect

    Smith, James N.; McMurry, Peter H.

    2015-11-12

    This final technical report describes our research activities that have, as the ultimate goal, the development of a model that explains growth rates of freshly nucleated particles. The research activities, which combine field observations with laboratory experiments, explore the relationship between concentrations of gas-phase species that contribute to growth and the rates at which those species are taken up. We also describe measurements of the chemical composition of freshly nucleated particles in a variety of locales, as well as properties (especially hygroscopicity) that influence their effects on climate. Our measurements include a self-organized, DOE-ARM funded project at the Southern Great Plains site, the New Particle Formation Study (NPFS), which took place during spring 2013. NPFS data are available to the research community on the ARM data archive, providing a unique suite observations of trace gas and aerosols that are associated with the formation and growth of atmospheric aerosol particles.

  18. Water uptake by organic aerosol and its influence on gas/particle partitioning of secondary organic aerosol in the United States

    NASA Astrophysics Data System (ADS)

    Jathar, Shantanu H.; Mahmud, Abdullah; Barsanti, Kelley C.; Asher, William E.; Pankow, James F.; Kleeman, Michael J.

    2016-03-01

    Organic aerosol (OA) is at least partly hygroscopic, i.e., water partitions into the organic phase to a degree determined by the relative humidity (RH), the organic chemical composition, and the particle size. This organic-phase water increases the aerosol mass and provides a larger absorbing matrix while decreasing its mean molecular weight, which can encourage additional condensation of semi-volatile organic compounds. Most regional and global atmospheric models account for water uptake by inorganic salts but do not explicitly account for organic-phase water and its subsequent impact on gas/particle partitioning of semi-volatile OA. In this work, we incorporated the organic-phase water model described by Pankow et al. (2015) into the UCD/CIT air quality model to simulate water uptake by OA and assessed its influence on total OA mass concentrations. The model was run for one summer month over two distinct regions: South Coast Air Basin (SoCAB) surrounding Los Angeles, California and the eastern United States (US). In SoCAB where the OA was dominated by non-hygroscopic primary OA (POA), there was very little organic-phase water uptake (0.1-0.2 μg m-3) and consequently very little enhancement (or growth) in total OA concentrations (OA + organic-phase water): a 3% increase in total OA mass was predicted for a 0.1 increase in relative humidity. In contrast, in the eastern US where secondary OA (SOA) from biogenic sources dominated the OA, substantial organic-phase water uptake and enhancement in total OA concentrations was predicted, even in urban locations. On average, the model predicted a 20% growth in total OA mass for a 0.1 increase in relative humidity; the growth was equivalent to a 250 nm particle with a hygroscopicity parameter (κ) of 0.15. Further, for the same relative humidity, the exact extent of organic-phase water uptake and total OA enhancement was found to be dependent on the particle mixing state. When the source-oriented mixing state of aerosols

  19. The dependence of aerosol light-scattering on RH over the Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Hegg, D. A.; Covert, D. S.; Crahan, K.; Jonssen, H.

    2002-04-01

    Measurements of the relative humidity dependence of aerosol light scattering are reported from three experimental venues over the Pacific Ocean. The measurement platform utilized was the CIRPAS Twin Otter aircraft. Results are compared with previous measurements at other locales and with theoretical models. The relatively low values of hygroscopicity obtained in marine air are consistent with a substantial organic component to the aerosol.

  20. Carbonaceous Aerosols and Radiative Effects Study (CARES), g1-aircraft, sedlacek sp2

    DOE Data Explorer

    Sedlacek, Art

    2011-08-30

    The primary objective of the Carbonaceous Aerosol and Radiative Effects Study (CARES) in 2010 was to investigate the evolution of carbonaceous aerosols of different types and their optical and hygroscopic properties in central California, with a focus on the Sacramento urban plume.

  1. Evolution of Organic Aerosols in the Atmosphere

    NASA Astrophysics Data System (ADS)

    Jimenez, J. L.; Canagaratna, M. R.; Donahue, N. M.; Prevot, A. S. H.; Zhang, Q.; Kroll, J. H.; DeCarlo, P. F.; Allan, J. D.; Coe, H.; Ng, N. L.; Aiken, A. C.; Docherty, K. S.; Ulbrich, I. M.; Grieshop, A. P.; Robinson, A. L.; Duplissy, J.; Smith, J. D.; Wilson, K. R.; Lanz, V. A.; Hueglin, C.; Sun, Y. L.; Tian, J.; Laaksonen, A.; Raatikainen, T.; Rautiainen, J.; Vaattovaara, P.; Ehn, M.; Kulmala, M.; Tomlinson, J. M.; Collins, D. R.; Cubison, M. J.; Dunlea, J.; Huffman, J. A.; Onasch, T. B.; Alfarra, M. R.; Williams, P. I.; Bower, K.; Kondo, Y.; Schneider, J.; Drewnick, F.; Borrmann, S.; Weimer, S.; Demerjian, K.; Salcedo, D.; Cottrell, L.; Griffin, R.; Takami, A.; Miyoshi, T.; Hatakeyama, S.; Shimono, A.; Sun, J. Y.; Zhang, Y. M.; Dzepina, K.; Kimmel, J. R.; Sueper, D.; Jayne, J. T.; Herndon, S. C.; Trimborn, A. M.; Williams, L. R.; Wood, E. C.; Middlebrook, A. M.; Kolb, C. E.; Baltensperger, U.; Worsnop, D. R.

    2009-12-01

    Organic aerosol (OA) particles affect climate forcing and human health, but their sources and evolution remain poorly characterized. We present a unifying model framework describing the atmospheric evolution of OA that is constrained by high-time-resolution measurements of its composition, volatility, and oxidation state. OA and OA precursor gases evolve by becoming increasingly oxidized, less volatile, and more hygroscopic, leading to the formation of oxygenated organic aerosol (OOA), with concentrations comparable to those of sulfate aerosol throughout the Northern Hemisphere. Our model framework captures the dynamic aging behavior observed in both the atmosphere and laboratory: It can serve as a basis for improving parameterizations in regional and global models.

  2. [Aerosol optical properties during different air-pollution episodes over Beijing].

    PubMed

    Shi, Chan-Zhen; Yu, Xing-Na; Zhou, Bin; Xiang, Lei; Nie, Hao-Hao

    2013-11-01

    Based on the 2005-2011 data from Aerosol Robotic Network (AERONET), this study conducted analysis on aerosol optical properties over Beijing during different air-pollution episodes (biomass burning, CNY firework, dust storm). The aerosol optical depth (AOD) showed notable increases in the air-pollution episodes while the AOD (at 440 nm) during dust storm was 4. 91, 4. 07 and 2.65 times higher as background, biomass burning and firework aerosols. AOD along with Angstrom exponent (alpha) can be used to determine the aerosol types. The dust aerosol had the highest AOD and the lowest alpha. The alpha value of firework (1.09) was smaller than biomass burning (1.21) and background (1.27), indicating that coarse particles were dominant in the former type. Higher AOD of burnings (than background) can be attributed to the optical extinction capability of black carbon aerosol. The single scattering albedo (SSA) was insensitive to wavelength. The SSA value of dust (0.934) was higher than background (0.878), biomass burning (0.921) and firework (0.905). Additionally, the extremely large SSA of burnings here maybe was caused by the aging smoke, hygroscopic growth and so on. The peak radius of aerosol volume size distributions were 0.1-0.2 microm and 2.24 -3.85 microm in clear and polluted conditions. The value of volume concentration ratio between coarse and fine particles was in the order of clear background (1.04), biomass burning (1.10), CNY firework (1.91) and dust storm (4.96) episode. PMID:24455916

  3. Efficient Nose-to-Lung (N2L) Aerosol Delivery with a Dry Powder Inhaler

    PubMed Central

    Golshahi, Laleh; Behara, Srinivas R.B.; Tian, Geng; Farkas, Dale R.; Hindle, Michael

    2015-01-01

    Abstract Purpose: Delivering aerosols to the lungs through the nasal route has a number of advantages, but its use has been limited by high depositional loss in the extrathoracic airways. The objective of this study was to evaluate the nose-to-lung (N2L) delivery of excipient enhanced growth (EEG) formulation aerosols generated with a new inline dry powder inhaler (DPI). The device was also adapted to enable aerosol delivery to a patient simultaneously receiving respiratory support from high flow nasal cannula (HFNC) therapy. Methods: The inhaler delivered the antibiotic ciprofloxacin, which was formulated as submicrometer combination particles containing a hygroscopic excipient prepared by spray-drying. Nose-to-lung delivery was assessed using in vitro and computational fluid dynamics (CFD) methods in an airway model that continued through the upper tracheobronchial region. Results: The best performing device contained a 2.3 mm flow control orifice and a 3D rod array with a 3-4-3 rod pattern. Based on in vitro experiments, the emitted dose from the streamlined nasal cannula had a fine particle fraction <5 μm of 95.9% and mass median aerodynamic diameter of 1.4 μm, which was considered ideal for nose-to-lung EEG delivery. With the 2.3-343 device, condensational growth in the airways increased the aerosol size to 2.5–2.7 μm and extrathoracic deposition was <10%. CFD results closely matched the in vitro experiments and predicted that nasal deposition was <2%. Conclusions: The developed DPI produced high efficiency aerosolization with significant size increase of the aerosol within the airways that can be used to enable nose-to-lung delivery and aerosol administration during HFNC therapy. PMID:25192072

  4. Effects of aerosol organics on cloud condensation nucleus (CCN) concentration and first indirect aerosol effect

    SciTech Connect

    Wang, J. X.; Lee, Y.- N.; Daum, Peter H.; Jayne, John T.; Alexander, M. L.

    2008-11-03

    Abstract. Aerosol microphysics, chemical composition, and CCN properties were measured on the Department of Energy Gulfstream-1 aircraft during the Marine Stratus/ Stratocumulus Experiment (MASE) conducted over the coastal waters between Point Reyes National Seashore and Monterey Bay, California, in July 2005. Aerosols measured during MASE included free tropospheric aerosols, marine boundary layer aerosols, and aerosols with high organic concentration within a thin layer above the cloud. Closure analysis was carried out for all three types of aerosols by comparing the measured CCN concentrations at 0.2% supersaturation to those predicted based on size distribution and chemical composition using K¨ohler theory. The effect of aerosol organic species on predicted CCN concentration was examined using a single hygroscopicity parameterization.

  5. Aerosol water parameterisation: a single parameter framework

    NASA Astrophysics Data System (ADS)

    Metzger, Swen; Steil, Benedikt; Abdelkader, Mohamed; Klingmüller, Klaus; Xu, Li; Penner, Joyce E.; Fountoukis, Christos; Nenes, Athanasios; Lelieveld, Jos

    2016-06-01

    We introduce a framework to efficiently parameterise the aerosol water uptake for mixtures of semi-volatile and non-volatile compounds, based on the coefficient, νi. This solute-specific coefficient was introduced in Metzger et al. (2012) to accurately parameterise the single solution hygroscopic growth, considering the Kelvin effect - accounting for the water uptake of concentrated nanometer-sized particles up to dilute solutions, i.e. from the compounds relative humidity of deliquescence (RHD) up to supersaturation (Köhler theory). Here we extend the νi parameterisation from single to mixed solutions. We evaluate our framework at various levels of complexity, by considering the full gas-liquid-solid partitioning for a comprehensive comparison with reference calculations using the E-AIM, EQUISOLV II and ISORROPIA II models as well as textbook examples. We apply our parameterisation in the EQuilibrium Simplified Aerosol Model V4 (EQSAM4clim) for climate simulations, implemented in a box model and in the global chemistry-climate model EMAC. Our results show (i) that the νi approach enables one to analytically solve the entire gas-liquid-solid partitioning and the mixed solution water uptake with sufficient accuracy, (ii) that ammonium sulfate mixtures can be solved with a simple method, e.g. pure ammonium nitrate and mixed ammonium nitrate and (iii) that the aerosol optical depth (AOD) simulations are in close agreement with remote sensing observations for the year 2005. Long-term evaluation of the EMAC results based on EQSAM4clim and ISORROPIA II will be presented separately.

  6. Aerosol water parameterization: a single parameter framework

    NASA Astrophysics Data System (ADS)

    Metzger, S.; Steil, B.; Abdelkader, M.; Klingmüller, K.; Xu, L.; Penner, J. E.; Fountoukis, C.; Nenes, A.; Lelieveld, J.

    2015-11-01

    We introduce a framework to efficiently parameterize the aerosol water uptake for mixtures of semi-volatile and non-volatile compounds, based on the coefficient, νi. This solute specific coefficient was introduced in Metzger et al. (2012) to accurately parameterize the single solution hygroscopic growth, considering the Kelvin effect - accounting for the water uptake of concentrated nanometer sized particles up to dilute solutions, i.e., from the compounds relative humidity of deliquescence (RHD) up to supersaturation (Köhler-theory). Here we extend the νi-parameterization from single to mixed solutions. We evaluate our framework at various levels of complexity, by considering the full gas-liquid-solid partitioning for a comprehensive comparison with reference calculations using the E-AIM, EQUISOLV II, ISORROPIA II models as well as textbook examples. We apply our parameterization in EQSAM4clim, the EQuilibrium Simplified Aerosol Model V4 for climate simulations, implemented in a box model and in the global chemistry-climate model EMAC. Our results show: (i) that the νi-approach enables to analytically solve the entire gas-liquid-solid partitioning and the mixed solution water uptake with sufficient accuracy, (ii) that, e.g., pure ammonium nitrate and mixed ammonium nitrate - ammonium sulfate mixtures can be solved with a simple method, and (iii) that the aerosol optical depth (AOD) simulations are in close agreement with remote sensing observations for the year 2005. Long-term evaluation of the EMAC results based on EQSAM4clim and ISORROPIA II will be presented separately.

  7. Aircraft Measurements of Aerosol Partitioning and Aging during EUCAARI-LONGREX

    NASA Astrophysics Data System (ADS)

    Morgan, W. T.; Allan, J. D.; Bower, K. N.; Coe, H.; Highwood, E. J.; McMeeking, G. R.; Northway, M. J.; Osborne, S. R.; Trembath, J.; Williams, P. I.

    2009-04-01

    mixed inorganic-organic system. This is exacerbated in areas exhibiting high relative humidity, such as the top of the boundary layer. Consequently, wet growth of the particulate matter substantially increases the AOD. Furthermore, chemical aging of the aerosol burden potentially alters the hygroscopic nature of the aerosol. Also, clouds forming at the top of the boundary layer entrain air from beneath them into the cloud. Enhanced aerosol concentrations in such air will lead to a modification of the microphysical properties of the cloud. Such modifications are known to modify the amount, lifetime and radiative impact of clouds, the so-called indirect effect of aerosols. The impacts of such phenomena upon the AOD will be further investigated via comparison with the European surface-based AErosol RObotic NETwork (AERONET). The sub-saturated and super-saturated properties of the aerosol will also be investigated based upon in-situ measurements from the aircraft.

  8. [Surgical hygroscopic bandages for amputations, secreting wounds and diabetes foot].

    PubMed

    Topolav, J; Kirov, G; Markov, G; Girov, K; Nedkov, P; Georgieva, A

    2010-01-01

    The authors adopt in clinical practice using of sterile hygroscopic wound dressings 'pampers type'. They use these dressings in 113 patients. The appropriate patients are these with limbs amputations, diabetic foot, suppurative and plenty secreting deep wounds, atonite and decubital wounds. The dressings are sterilised using paraformaldehyde sterilization which do not injure the synthetic materials. The hygroscopic dressings are non- allergic and are well tolerated by the patients. Using these dressings facilitate the medical team work and help to reduce the contamination of the hospital linen and the patients coverlet. They help for accelerating the wound healing process. They are also economic effective by reducing the amount of used dressing material. PMID:21972719

  9. 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

  10. Light scattering from sea-salt aerosols at Interagency Monitoring of Protected Visual Environments (IMPROVE) sites.

    PubMed

    Lowenthal, Douglas; Kumar, Naresh

    2006-05-01

    A method is described to estimate light scattering (Bsp) by sea-salt aerosols at coastal locations in the Interagency Monitoring of Protected Visual Environments (IMPROVE) network. Dry mass scattering efficiencies for fine and coarse sea-salt particles were based on previously measured dry sea-salt size distributions. Enhancement of sea-salt particle scattering by hygroscopic growth was based on NaCl water activity data. Sea-salt aerosol mass at the IMPROVE site in the Virgin Islands (VIIS) was estimated from strontium (Sr) concentrations in IMPROVE aerosol samples. Estimated Bsp, including contributions from sea-salt mass based on Sr, agreed well with measured Bsp at the VIIS IMPROVE site. On average, sea salt accounted for 52% of estimated Bsp at this site. Sea-salt aerosol mass cannot be reliably estimated from Sr unless its crustal enrichment factor exceeds 10. Sodium (Na) concentrations are not accurately determined by X-ray fluorescence analysis in IMPROVE samples. It is recommended that Na be measured in the fine and coarse modes by a more appropriate method, such as atomic absorption spectroscopy or ion chromatography, to account for scattering by sea-salt particles at IMPROVE sites where such contributions may be significant. PMID:16739800

  11. Growth of BaTiO3-PVDF composite thick films by using aerosol deposition

    NASA Astrophysics Data System (ADS)

    Cho, Sung Hwan; Yoon, Young Joon

    2016-01-01

    Barium titanate (BaTiO3)-polyvinylidene fluoride (PVDF) composite thick films were grown by using aerosol deposition at room temperature with BaTiO3 and PVDF powders. To produce a uniform composition in ceramic and polymer composite films, which show a substantial difference in specific gravity, we used PVDF-coated BaTiO3 powders as the starting materials. An examination of the microstructure confirmed that the BaTiO3 were well distributed in the PVDF matrix in the form of a 0 - 3 compound. The crystallite size in the BaTiO3-PVDF composite thick films was 5 ˜ 50 times higher than that in pure BaTiO3 thick films. PVDF plays a role in suppressing the fragmentation of BaTiO3 powder during the aerosol deposition process and in controlling the relative permittivity.

  12. Long-range transport across the Atlantic in summertime does not enhance the hygroscopicity of African mineral dust

    NASA Astrophysics Data System (ADS)

    Denjean, C.; Caquineau, S.; Desboeufs, K.; Laurent, B.; Maille, M.; Quiñones Rosado, M.; Vallejo, P.; Mayol-Bracero, O. L.; Formenti, P.

    2015-09-01

    We present the first direct evidence that the hygroscopic properties of super micron (>1 µm) African dust particles did not change despite undergoing long-range transport across the Atlantic toward the Caribbean. Concurrent measurements of chemical composition show that most of mineral dust was chemically unprocessed and externally mixed. A minor portion of mineral dust was internally mixed with sulfate and chloride (~13-24% by number) or aggregated with sea-salt particles (~3-6%). Only dust particles aggregated with sea salt showed significant hygroscopic growth above 75% relative humidity (RH), resulting in a decrease in extinction mass efficiency by up to a factor 2.2. All other dust particles did not take up significant amounts of water when exposed to up to 94% RH. These results demonstrate that the direct radiative effect of African dust in this region remained independent of RH and an external mixing state could be considered for evaluating the climate effects of dust.

  13. The evolution of the physicochemical properties of aerosols in the atmosphere

    NASA Astrophysics Data System (ADS)

    Tomlinson, Jason Michael

    A Differential Mobility Analyzer/Tandem Differential Mobility Analyzer (DMA/TDMA) system was used to measure simultaneously the size distribution and hygroscopicity of the ambient aerosol population. The system was operated aboard the National Center for Atmospheric Research/National Science Foundation (NCAR/NSF) C-130 during the 2006 Megacity Initiative: Local and Global Research Observations (MILAGRO) field campaign followed by the 2006 Intercontinental Chemical Transport Experiment -- Phase B (INTEX-B) field campaign. The research flights for the MILAGRO campaign were conducted within the Mexico City basin and the region to the northeast within the pollution plume. The aerosol within the basin is dominated by organics with an average measured kappa value of 0.21 +/- 0.18, 0.13 +/- 0.09, 0.09 +/- 0.06, 0.14 +/- 0.07, and 0.17 +/- 0.04 for dry particle diameters of 0.025, 0.050, 0.100, 0.200, and 0.300 mum, respectively. As the aerosols are transported away from the Mexico City Basin, secondary organic aerosol formation through oxidation and condensation of sulfate on the aerosols surface rapidly increases the solubility of the aerosol. The most pronounced change occurs for a 0.100 mum diameter aerosol where, after 6 hours of transport, the average kappa value increased by a factor of 3 to a kappa of 0.29 +/- 0.13. The rapid increase in solubility increases the fraction of the aerosol size distribution that could be activated within a cloud. The research flights for the INTEX-B field campaign investigated the evolution of the physicochemical properties of the Asian aerosol plume after 3 to 7 days of transport. The Asian aerosol within the free troposphere exhibited a bimodal growth distribution roughly 50% of the time. The more soluble mode of the growth distribution contributed between 67-80% of the overall growth distribution and had an average kappa between 0.40 and 0.53 for dry particle diameters of 0.025, 0.050, 0.100, and 0.300 mum. The secondary mode was

  14. Size distribution, chemical composition, and hygroscopicity of fine particles emitted from an oil-fired heating plant.

    PubMed

    Happonen, Matti; Mylläri, Fanni; Karjalainen, Panu; Frey, Anna; Saarikoski, Sanna; Carbone, Samara; Hillamo, Risto; Pirjola, Liisa; Häyrinen, Anna; Kytömäki, Jorma; Niemi, Jarkko V; Keskinen, Jorma; Rönkkö, Topi

    2013-12-17

    Heavy fuel oil (HFO) is a commonly used fuel in industrial heating and power generation and for large marine vessels. In this study, the fine particle emissions of a 47 MW oil-fired boiler were studied at 30 MW power and with three different fuels. The studied fuels were HFO, water emulsion of HFO, and water emulsion of HFO mixed with light fuel oil (LFO). With all the fuels, the boiler emitted considerable amounts of particles smaller than 200 nm in diameter. Further, these small particles were quite hygroscopic even as fresh and, in the case of HFO+LFO emulsion, the hygroscopic growth of the particles was dependent on particle size. The use of emulsions and the addition of LFO to the fuel had a reducing effect on the hygroscopic growth of particles. The use of emulsions lowered the sulfate content of the smallest particles but did not affect significantly the sulfate content of particles larger than 42 nm and, further, the addition of LFO considerably increased the black carbon content of particulate matter. The results indicate that even the fine particles emitted from HFO based combustion can have a significant effect on cloud formation, visibility, and air quality. PMID:24245691

  15. 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.

  16. Particle hygroscopicity and its link to chemical composition in the urban atmosphere of Beijing, China during summertime

    NASA Astrophysics Data System (ADS)

    Wu, Z. J.; Zheng, J.; Shang, D. J.; Du, Z. F.; Wu, Y. S.; Zeng, L. M.; Wiedensohler, A.; Hu, M.

    2015-04-01

    Simultaneous measurements of particle number size distribution, particle hygroscopic properties, and size-resolved chemical composition were made during the summer of 2014 in Beijing, China. During the measurement period, the median hygroscopicity parameters (κ) of 50, 100, 150, 200, and 250 nm particles are respectively 0.15, 0.19, 0.22, 0.27, and 0.29, showing an increasing trend with increasing particle size. When PM2.5 mass concentration is greater than 50 μg m-3, the fractions of the hydrophilic mode for 150, 250, 350 nm particles increased towards 1 as PM2.5 mass concentration increased. This indicates that aged particles dominated during severe pollution periods in the atmosphere of Beijing. Particle hygroscopic growth can be well predicted using high time-resolution size-resolved chemical composition derived from AMS measurement on a basis of ZSR mixing rule. An empirical relationship between κ of organic fraction (κorg) and oxygen to carbon ratio (O : C) (κorg= 0.08·O : C+0.02) is obtained. During new particle formation event associating with strongly active photochemistry, the hygroscopic growth factor or κ of newly formed particles is greater than for particle with the same sizes during non-NPF periods. A quick transformation from external mixture to internal mixture for pre-existing particles (for example 250 nm particle) was observed. Such transformations can modify the state of mixture of pre-exiting particles and thus modify properties such as the light absorption coefficient and cloud condensation nuclei activation.

  17. Shipboard Sunphotometer Measurements of Aerosol Optical Depth Spectra and Columnar Water Vapor During ACE-2 and Comparison with Selected Land, Ship, Aircraft, and Satellite Measurements

    NASA Technical Reports Server (NTRS)

    Livingston, John M.; Kapustin, Vladimir N.; Schmid, Beat; Russell, Philip B.; Quinn, Patricia K.; Bates, Timothy S.; Durkee, Philip A.; Smith, Peter J.; Freudenthaler, Volker; Wiegner, Matthias; Covert, Dave S.; Gasso, Santiago; Hegg, Dean; Collins, Donald R.; Flagan, Richard C.; Seinfeld, John H.; Vitale, Vito; Tomasi, Claudio

    2000-01-01

    Analyses of aerosol optical depth (AOD) and colurnmn water vapor (CWV) measurements acquired with NASA Ames Research Center's 6-channel Airborne Tracking Sunphotometer (AATS-6) operated aboard the R/V Professor Vodyanitskiy during the 2nd Aerosol Characterization Experiment (ACE-2) are discussed. Data are compared with various in situ and remote measurements for selected cases. The focus is on 10 July, when the Pelican airplane flew within 70 km of the ship near the time of a NOAA-14/AVHRR satellite overpass and AOD measurements with the 14-channel Ames Airborne Tracking Sunphotometer (AATS-14) above the marine boundary layer (MBL) permitted calculation of AOD within the MBL from the AATS-6 measurements. A detailed column closure test is performed for MBL AOD on 10 July by comparing the AATS-6 MBL AODs with corresponding values calculated by combining shipboard particle size distribution measurements with models of hygroscopic growth and radiosonde humidity profiles (plus assumptions on the vertical profile of the dry particle size distribution and composition). Large differences (30-80% in the mid-visible) between measured and reconstructed AODs are obtained, in large part because of the high sensitivity of the closure methodology to hygroscopic growth models, which vary considerably and have not been validated over the necessary range of particle size/composition distributions. The wavelength dependence of AATS-6 AODs is compared with the corresponding dependence of aerosol extinction calculated from shipboard measurements of aerosol size distribution and of total scattering mearured by a shipboard integrating nephelometer for several days. Results are highly variable, illustrating further the great difficulty of deriving column values from point measurements. AATS-6 CWV values are shown to agree well with corresponding values derived from radiosonde measurements during 8 soundings on 7 days and also with values calculated from measurements taken on 10 July with

  18. Experimentally measured morphology of biomass burning aerosol and its impacts on CCN ability

    NASA Astrophysics Data System (ADS)

    Giordano, M.; Espinoza, C.; Asa-Awuku, A.

    2015-02-01

    This study examines the morphological properties of freshly emitted and atmospherically aged aerosols from biomass burning. The impacts of particle morphology assumptions on hygroscopic predictions are examined. Chamber experiments were conducted at the University of California, Riverside, Center for Environmental Research and Technology (CE-CERT) atmospheric processes lab using two biomass fuel sources: manzanita and chamise. Morphological data was obtained through the use of an aerosol particle mass analyzer (APM), scanning mobility particle sizer (SMPS) system and transmission electron microscope (TEM). Data from these instruments was used to calculate both a dynamic shape factor and a fractal-like dimension for the biomass burning emissions. This data was then used with κ-Köhler theory to adjust the calculated hygroscopicity for experimentally determined morphological characteristics of the aerosol. Laboratory measurement of biomass burning aerosol from two chaparral fuels show that particles are nonspherical with dynamic shape factors greater than 1.15 for aerosol sizes relevant to cloud condensation nuclei (CCN) activation. Accounting for particle morphology can shift the hygroscopicity parameter by 0.15 or more. To our knowledge, this work provides the first laboratory chamber measurements of morphological characteristics for biomass burning cloud condensation nuclei and provides experimental particle shape evidence to support the variation in reported hygroscopicities of the complex aerosol.

  19. 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

  20. Size dependence of phase transitions in aerosol nanoparticles

    PubMed Central

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

    2015-01-01

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

  1. Aerosol-computational fluid dynamics modeling of ultrafine and black carbon particle emission, dilution, and growth near roadways

    NASA Astrophysics Data System (ADS)

    Huang, L.; Gong, S. L.; Gordon, M.; Liggio, J.; Staebler, R.; Stroud, C. A.; Lu, G.; Mihele, C.; Brook, J. R.; Jia, C. Q.

    2014-12-01

    Many studies have shown that on-road vehicle emissions are the dominant source of ultrafine particles (UFPs; diameter < 100 nm) in urban areas and near-roadway environments. In order to advance our knowledge on the complex interactions and competition among atmospheric dilution, dispersion, and dynamics of UFPs, an aerosol dynamics-computational fluid dynamics (CFD) coupled model is developed and validated against field measurements. A unique approach of applying periodic boundary conditions is proposed to model pollutant dispersion and dynamics in one unified domain from the tailpipe level to the ambient near-road environment. This approach significantly reduces the size of the computational domain, and therefore allows fast simulation of multiple scenarios. The model is validated against measured turbulent kinetic energy (TKE) and horizontal gradient of pollution concentrations perpendicular to a major highway. Through a model sensitivity analysis, the relative importance of individual aerosol dynamical processes on the total particle number concentration (N) and particle number-size distribution (PSD) near a highway is investigated. The results demonstrate that (1) coagulation has a negligible effect on N and particle growth, (2) binary homogeneous nucleation (BHN) of H2SO4-H2O is likely responsible for elevated N closest to the road, and (3) N and particle growth are very sensitive to the condensation of semi-volatile organics (SVOCs), particle dry deposition, and the interaction between these processes. The results also indicate that, without the proper treatment of the atmospheric boundary layer (i.e., its wind profile and turbulence quantities), the nucleation rate would be underestimated by a factor of 5 in the vehicle wake region due to overestimated dilution. Therefore, introducing atmospheric boundary layer (ABL) conditions to activity-based emission models may potentially improve their performance in estimating UFP traffic emissions.

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

    NASA Astrophysics Data System (ADS)

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

    2014-06-01

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

  3. Organic Nitrate Contribution to New Particle Formation and Growth in Secondary Organic Aerosols from α-Pinene Ozonolysis.

    PubMed

    Berkemeier, Thomas; Ammann, Markus; Mentel, Thomas F; Pöschl, Ulrich; Shiraiwa, Manabu

    2016-06-21

    The chemical kinetics of organic nitrate production during new particle formation and growth of secondary organic aerosols (SOA) were investigated using the short-lived radioactive tracer (13)N in flow-reactor studies of α-pinene oxidation with ozone. Direct and quantitative measurements of the nitrogen content indicate that organic nitrates accounted for ∼40% of SOA mass during initial particle formation, decreasing to ∼15% upon particle growth to the accumulation-mode size range (>100 nm). Experiments with OH scavengers and kinetic model results suggest that organic peroxy radicals formed by α-pinene reacting with secondary OH from ozonolysis are key intermediates in the organic nitrate formation process. The direct reaction of α-pinene with NO3 was found to be less important for particle-phase organic nitrate formation. The nitrogen content of SOA particles decreased slightly upon increase of relative humidity up to 80%. The experiments show a tight correlation between organic nitrate content and SOA particle-number concentrations, implying that the condensing organic nitrates are among the extremely low volatility organic compounds (ELVOC) that may play an important role in the nucleation and growth of atmospheric nanoparticles. PMID:27219077

  4. The Influence of topography on formation characteristics of hygroscopic and condensate water in Shapotou

    NASA Astrophysics Data System (ADS)

    Pan, Yanxia; Li, Xinrong; Hui, Rong; Zhao, Yang

    2016-04-01

    The formation characteristics of hygroscopic and condensate water for different topographic positions were observed using the PVC pipes manual weighing and CPM method in the typical mobile dunes fixed by straw checkerboard barriers in Shapotou. The results indicated that the formation amounts and duration of hygroscopic and condensate water show moderate spatial heterogeneity at the influence of topography. The formation amounts of hygroscopic and condensate water at different aspects conform to the classical convection model, in which the hygroscopic and condensate water amounts are highest at hollow, and windward aspect gets more water than leeward aspect, the hygroscopic and condensate water amounts at different aspects are expressed as: hollow>Western-faced aspect>Northern-faced aspect>hilltop>Southern-faced aspect>Eastern-faced aspect. The hygroscopic and condensate water amounts at different slope positions for every aspect are as follows: the foot of slope>middle slope>hilltop. A negatively linear correlation is got between slope angles and hygroscopic and condensate water amounts, hygroscopic and condensate water amounts decrease gradually along with the increase of slope angles, the amounts of hygroscopic and condensate water at the vertical aspect are only half of horizontal aspect, which indicated topography were important influence factors for the formation of the hygroscopic and condensate water in arid area.

  5. Contrasting the Evaporation and Condensation of Water from Glassy and Amorphous Aerosol Particles

    NASA Astrophysics Data System (ADS)

    Reid, J. P.; Bones, D. L.; Power, R.; Lienhard, D.; Krieger, U. K.

    2012-04-01

    The partitioning of water between the condensed and gas phases in atmospheric aerosol is usually assumed to occur instantaneously and to be regulated by solution thermodynamics. However, the persistence of high viscosity, glassy and amorphous aerosol to low relative humidity without crystallisation occurring is now widely recognised, suggesting that the timescale for water transport to or from the particle during condensation or evaporation may be significant. A kinetic limitation on water transport could have important implications for understanding hygroscopic growth measurements made on ambient particles, the ability of particles to act as ice nuclei or cloud condensation nuclei, the kinetics of chemical aging/heterogeneous chemistry, and the rate or condensation/evaporation of semi-volatile organic components. In this study we will report on measurements of the timescale of water transport to and from glassy aerosol and ultra-high viscosity solution droplets using aerosol optical tweezers to investigate the time-response of single particles to changes in relative humidity. As a benchmark system, mixed component aerosol particles containing sucrose and sodium chloride have been used; varying the mole fractions of the two solutes allows a wide range of solution viscosities to be studied. We will show that coarse particles can take many thousands of seconds to equilibrate in size and that the timescale correlates with the estimated bulk viscosity of the particle. We will also confirm that significant inhomogeneities in particle composition can be established during evaporation or condensation. Using the experimental data to benchmark a model for equilibration time, predictions can be made of the timescale for the equilibration of accumulation mode particles during water condensation or evaporation and these predictions will be described and their significance explored. Finally, the coalescence dynamics of highly viscous aerosol particles will be reported

  6. Characterization of Ambient Black Carbon Aerosols

    NASA Astrophysics Data System (ADS)

    Zhang, R.; Levy, M. E.; Zheng, J.; Molina, L. T.

    2013-12-01

    Because of the strong absorption over a broad range of the electromagnetic spectra, black carbon (BC) is a key short-lived climate forcer, which contributes significantly to climate change by direct radiative forcing and is the second most important component causing global warming after carbon dioxide. The impact of BC on the radiative forcing of the Earth-Atmosphere system is highly dependent of the particle properties. In this presentation, emphasis will be placed on characterizing BC containing aerosols in at the California-Mexico border to obtain a greater understanding of the atmospheric aging and properties of ambient BC aerosols. A comprehensive set of directly measured aerosol properties, including the particle size distribution, effective density, hygroscopicity, volatility, and several optical properties, will be discussed to quantify the mixing state and composition of ambient particles. In Tijuana, Mexico, submicron aerosols are strongly influenced by vehicle emissions; subsequently, the BC concentration in Tijuana is considerably higher than most US cities with an average BC concentration of 2.71 × 2.65 g cm-3. BC accounts for 24.75 % × 9.44 of the total submicron concentration on average, but periodically accounts for over 50%. This high concentration of BC strongly influences many observed aerosol properties such as single scattering albedo, hygroscopicity, effective density, and volatility.

  7. Atmospheric Chemistry: Nature's plasticized aerosols

    NASA Astrophysics Data System (ADS)

    Ziemann, Paul J.

    2016-01-01

    The structure of atmospheric aerosol particles affects their reactivity and growth rates. Measurements of aerosol properties over the Amazon rainforest indicate that organic particles above tropical rainforests are simple liquid drops.

  8. A case study of Asian dust storm particles: chemical composition, reactivity to SO2 and hygroscopic properties.

    PubMed

    Ma, Qingxin; Liu, Yongchun; Liu, Chang; Ma, Jinzhu; He, Hong

    2012-01-01

    Mineral dust comprises a great fraction of the global aerosol loading, but remains the largest uncertainty in predictions of the future climate due to its complexity in composition and physico-chemical properties. In this work, a case study characterizing Asian dust storm particles was conducted by multiple analysis methods, including SEM-EDS, XPS, FT-IR, BET, TPD/mass and Knudsen cell/mass. The morphology, elemental fraction, source distribution, true uptake coefficient for SO2, and hygroscopic behavior were studied. The major components of Asian dust storm particles are aluminosilicate, SiO2 and CaCO3, with organic compounds and inorganic nitrate coated on the surface. It has a low reactivity towards SO2 with a true uptake coefficient, 5.767 x 10(-6), which limits the conversion of SO2 to sulfate during dust storm periods. The low reactivity also means that the heterogeneous reactions of SO2 in both dry and humid air conditions have little effect on the hygroscopic behavior of the dust particles. PMID:22783615

  9. The impacts of aerosol loading, composition, and water uptake on aerosol extinction variability in the Baltimore-Washington, D.C. region

    NASA Astrophysics Data System (ADS)

    Beyersdorf, A. J.; Ziemba, L. D.; Chen, G.; Corr, C. A.; Crawford, J. H.; Diskin, G. S.; Moore, R. H.; Thornhill, K. L.; Winstead, E. L.; Anderson, B. E.

    2016-01-01

    In order to utilize satellite-based aerosol measurements for the determination of air quality, the relationship between aerosol optical properties (wavelength-dependent, column-integrated extinction measured by satellites) and mass measurements of aerosol loading (PM2.5 used for air quality monitoring) must be understood. This connection varies with many factors including those specific to the aerosol type - such as composition, size, and hygroscopicity - and to the surrounding atmosphere, such as temperature, relative humidity (RH), and altitude, all of which can vary spatially and temporally. During the DISCOVER-AQ (Deriving Information on Surface conditions from Column and Vertically Resolved Observations Relevant to Air Quality) project, extensive in situ atmospheric profiling in the Baltimore, MD-Washington, D.C. region was performed during 14 flights in July 2011. Identical flight plans and profile locations throughout the project provide meaningful statistics for determining the variability in and correlations between aerosol loading, composition, optical properties, and meteorological conditions. Measured water-soluble aerosol mass was composed primarily of ammonium sulfate (campaign average of 32 %) and organics (57 %). A distinct difference in composition was observed, with high-loading days having a proportionally larger percentage of sulfate due to transport from the Ohio River Valley. This composition shift caused a change in the aerosol water-uptake potential (hygroscopicity) such that higher relative contributions of inorganics increased the bulk aerosol hygroscopicity. These days also tended to have higher relative humidity, causing an increase in the water content of the aerosol. Conversely, low-aerosol-loading days had lower sulfate and higher black carbon contributions, causing lower single-scattering albedos (SSAs). The average black carbon concentrations were 240 ng m-3 in the lowest 1 km, decreasing to 35 ng m-3 in the free troposphere (above

  10. Dependence of the drizzle growth process on the cloud top height and its relevance to the aerosol vertical profile

    NASA Astrophysics Data System (ADS)

    Kawamoto, K.; Suzuki, K.

    2013-12-01

    Transitional processes among cloud droplets, drizzle and raindrops are still uncertain and more efforts are required for the better understanding. In this situation, difference in the drizzle growth process was examined according to the cloud top height using the CloudSat and MODIS synergetic datasets. From the CloudSat products such as 2B-GEOPROF, 2B-TAU, ECMWF-AUX, only one-layered water clouds whose top temperatures were warmer than 273K were extracted over China (a circular area having a diameter of 1800km of the center at 35°N and 120°E) and over ocean (a circular area having a diameter of 1500km of the center at 35°N and 150°E). Then a threshold of 3km of the cloud top height was adopted to divide the extracted clouds into upper and lower cases. First, the probability distribution functions (PDF) of the cloud droplet number density (Nc) and the effective particle radius (Re) were calculated for these four cases (land/ocean/upper/lower). Nc was obtained assuming the adiabatic liquid water content from MODIS-derived cloud optical depth and Re. Oceanic clouds had fewer Nc than land clouds, and almost the same for upper and lower cases. Land clouds had more Nc for the lower case than for the higher case. On the other hand, oceanic clouds had larger Re than land clouds, and almost the same for upper and lower cases. Land clouds had smaller Re for the lower case than for the higher case. These results quite agreed with our existing knowledge on the vertical profile of the aerosol number concentration over ocean (pristine) and land (polluted). Although the number of aerosol particles is fewer and almost the same regardless of the height over the ocean, it is more near the surface and it rapidly decreases according to the height over the land. Next, examining PDF of the radar reflectivity (Ze), we found that although PDFs of Ze were almost the same for oceanic clouds regardless of the cloud top height, PDF of land lower clouds were less frequent at around from

  11. UManSysProp: an online facility for molecular property prediction and atmospheric aerosol calculations

    NASA Astrophysics Data System (ADS)

    Topping, D.; Barley, M. H.; Bane, M.; Higham, N.; Aumont, B.; McFiggans, G.

    2015-11-01

    In this paper we describe the development and application of a new web based facility, UManSysProp (http://umansysprop.seaes.manchester.ac.uk), for automating predictions of molecular and atmospheric aerosol properties. Current facilities include: pure component vapour pressures, critical properties and sub-cooled densities of organic molecules; activity coefficient predictions for mixed inorganic-organic liquid systems; hygroscopic growth factors and CCN activation potential of mixed inorganic/organic aerosol particles; absorptive partitioning calculations with/without a treatment of non-ideality. The aim of this new facility is to provide a single point of reference for all properties relevant to atmospheric aerosol that have been checked for applicability to atmospheric compounds where possible. The group contribution approach allows users to upload molecular information in the form of SMILES strings and UManSysProp will automatically extract the relevant information for calculations. Built using open source chemical informatics, and hosted at the University of Manchester, the facilities are provided via a browser and device-friendly web-interface, or can be accessed using the user's own code via a JSON API. In this paper we demonstrate its use with specific examples that can be simulated using the web-browser interface.

  12. Characteristics and composition of atmospheric aerosols in Phimai, central Thailand during BASE-ASIA

    NASA Astrophysics Data System (ADS)

    Li, Can; Tsay, Si-Chee; Hsu, N. Christina; Kim, Jin Young; Howell, Steven G.; Huebert, Barry J.; Ji, Qiang; Jeong, Myeong-Jae; Wang, Sheng-Hsiang; Hansell, Richard A.; Bell, Shaun W.

    2013-10-01

    Comprehensive measurements of atmospheric aerosols were made in Phimai, central Thailand (15.183°N, 102.565°E, elevation: 206 m) during the BASE-ASIA field experiment from late February to early May in 2006. The observed aerosol loading was sizable for this rural site (mean aerosol scattering: 108 ± 64 Mm-1; absorption: 15 ± 8 Mm-1; PM10 concentration: 33 ± 17 μg m-3), and dominated by submicron particles. Major aerosol compounds included carbonaceous (OC: 9.5 ± 3.6 μg m-3; EC: 2.0 ± 2.3 μg m-3) and secondary species (SO42-: 6.4 ± 3.7 μg m-3, NH4+: 2.2 ± 1.3 μg m-3). While the site was seldom under the direct influence of large forest fires to its north, agricultural fires were ubiquitous during the experiment, as suggested by the substantial concentration of K+ (0.56 ± 0.33 μg m-3). Besides biomass burning, aerosols in Phimai during the experiment were also strongly influenced by industrial and vehicular emissions from the Bangkok metropolitan region and long-range transport from southern China. High humidity played an important role in determining the aerosol composition and properties in the region. Sulfate was primarily formed via aqueous phase reactions, and hygroscopic growth could enhance the aerosol light scattering by up to 60%, at the typical morning RH level of 85%. The aerosol single scattering albedo demonstrated distinct diurnal variation, ranging from 0.86 ± 0.04 in the evening to 0.92 ± 0.02 in the morning. This experiment marks the first time such comprehensive characterization of aerosols was made for rural central Thailand. Our results indicate that aerosol pollution has developed into a regional problem for northern Indochina, and may become more severe as the region's population and economy continue to grow.

  13. Volatility and oxidative aging of aqueous maleic acid aerosol droplets and the dependence on relative humidity.

    PubMed

    Dennis-Smither, Benjamin J; Marshall, Frances H; Miles, Rachael E H; Preston, Thomas C; Reid, Jonathan P

    2014-07-31

    The microphysical structure and heterogeneous oxidation by ozone of single aerosol particles containing maleic acid (MA) has been studied using aerosol optical tweezers and cavity enhanced Raman spectroscopy. The evaporation rate of MA from aqueous droplets has been measured over a range of relative humidities and the pure component vapor pressure determined to be (1.7 ± 0.2) × 10(-3) Pa. Variation in the refractive index (RI) of an aqueous MA droplet with relative humidity (RH) allowed the subcooled liquid RI of MA to be estimated as 1.481 ± 0.001. Measurements of the hygroscopic growth are shown to be consistent with equilibrium model predictions from previous studies. Simultaneous measurements of the droplet composition, size, and refractive index have been made during ozonolysis at RHs in the range 50-80%, providing insight into the volatility of organic products, changes in the droplet hygroscopicity, and optical properties. Exposure of the aqueous droplets to ozone leads to the formation of products with a wide range of volatilities spanning from involatile to volatile. Reactive uptake coefficients show a weak dependence on ozone concentration, but no dependence on RH or salt concentration. The time evolving RI depends significantly on the RH at which the oxidation proceeds and can even show opposing trends; while the RI increases with ozone exposure at low relative humidity, the RI decreases when the oxidation proceeds at high relative humidity. The variations in RI are broadly consistent with a framework for predicting RIs for organic components published by Cappa et al. ( J. Geophys. Res. 2011 , 116 , D15204 ). Once oxidized, particles are shown to form amorphous phases on drying rather than crystallization, with slow evaporation kinetics of residual water. PMID:25003240

  14. The Effect Of Organic Surfactants On The Properties Of Common Hygroscopic Particles: Effective Densities, Reactivity And Water Evaporation Of Surfactant Coated Particles

    NASA Astrophysics Data System (ADS)

    Cuadrarodriguez, L.; Zelenyuk, A.; Imre, D.; Ellison, B.

    2006-12-01

    Measurements of atmospheric aerosol compositions routinely show that organic compounds account for a very large fraction of the particle mass. The organic compounds that make up this aerosol mass represent a wide range of molecules with a variety of properties. Many of the particles are composed of hygroscopic salts like sulfates, nitrates and sea-salt internally mixed with organics. While the properties of the hygroscopic salts are known, the effect of the organic compounds on the microphysical and chemical properties which include CCN activity is not clear. .One particularly interesting class of internally mixed particles is composed of aqueous salts solutions that are coated with organic surfactants which are molecules with long aliphatic chain and a water soluble end. Because these molecules tend to coat the particles' surfaces, a monolayer might be sufficient to drastically alter their hygroscopic properties, their CCN activity, and reactivity. The aliphatic chains, being exposed to the oxidizing atmosphere are expected to be transformed through heterogeneous chemistry, yielding complex products with mixed properties. We will report the results from a series of observations on ammonium sulfate, sodium chloride and sea salt particles coated with three types of surfactant molecules: sodium lauryl sulfate, sodium oleate and laurtrimonium chloride. We have been able to measure the effective densities of internally mixed particles with a range of surfactant concentration that start below a monolayer and extend all the way to particles composed of pure surfactant. For many of the measurements the data reveal a rather complex picture that cannot be simply interpreted in terms of the known pure-compound densities. For unsaturated hydrocarbons we observed and quantified the effect of oxidation by ozone on particle size, effective density and individual particle mass spectral signatures. One of the more important properties of these surfactants is that they can form a

  15. Characteristics and Composition of Atmospheric Aerosols in Phimai, Central Thailand During BASE-ASIA

    NASA Technical Reports Server (NTRS)

    Li, Can; Tsay, Si-Chee; Hsu, N. Christina; Kim, Jin Young; Howell, Steven G.; Huebert, Barry J.; Ji, Qiang; Jeong, Myeong-Jae; Wang, Sheng-Hsiang; Hansell, Richard A.; Bell, Shaun W.

    2012-01-01

    +/- 8 Mm(exp -1); PM(sub 10) concentration: 33 +/- 17 miro-g/ cubic m and dominated by submicron particles. Major aerosol compounds included carbonaceous (OC: 9.5 +/- 3.6miro-g/ cubic m; EC: 2.0 2.3 miro-g/ cubic m and secondary species (SO4(2-): 6.4 +/- 3.7 miro-g/ cubic m, NH4(+): 2.2 +/- 1.3 miro-g/ cubic m). While the site was seldom under the direct influence of large forest fires to its north, agricultural fires were ubiquitous during the experiment, as suggested by the substantial concentration of K+ (0.56 +/- 0.33 micro-g/ cubic m). Besides biomass burning, aerosols in Phimai during the experiment were also strongly influenced by industrial and vehicular emissions from the Bangkok metropolitan region and long-range transport from southern China. High humidity played an important role in determining the aerosol composition and properties in the region. Sulfate was primarily formed via aqueous phase reactions, and hygroscopic growth could enhance the aerosol light scattering by up to 60%, at the typical morning RH level of 85%. The aerosol single scattering albedo demonstrated distinct diurnal variation, ranging from 0.86 +/- 0.04 in the evening to 0.92 +/- 0.02 in the morning. This experiment marks the first time such comprehensive characterization of aerosols was made for rural central Thailand. Our results indicate that aerosol pollution has developed into a regional problem for northern Indochina, and may become more severe as the region's population and economy continue to grow.

  16. Droplet Growth Kinetics in Various Environments

    NASA Astrophysics Data System (ADS)

    Raatikainen, T. E.; Lathem, T. L.; Moore, R.; Lin, J. J.; Cerully, K. M.; Padro, L.; Lance, S.; Cozic, J.; Anderson, B. E.; Nenes, A.

    2012-12-01

    for various instrument settings and also in the case of high CCN concentrations when water vapor depletion decreases supersaturation and droplet size (Lathem and Nenes, Aerosol Sci. Tech., 45, 604-615, 2011). The model also accounts for aerosol hygroscopicity and size distribution variations, which can have significant effects on the droplet size. We have examined cloud droplet activation and growth kinetics by analyzing several DMT CCN counter data sets collected from various environments including boreal forests, arctic areas, fresh and aged biomass burning plumes, and polluted and biogenically influenced urban areas (Raatikainen et al., In preparation, 2012). Model simulations show that the variations in observed droplet size are caused by water vapor depletion effects, changes in dry particle size distributions and hygroscopicity, and changes in instrument supersaturation profiles. This means that fast droplet growth kinetics with water uptake coefficient close to 0.2 is prevalent at least for the studied environments.

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

    SciTech Connect

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

    2013-12-09

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

  18. Pathophysiological and disease constraints on aerosol delivery

    SciTech Connect

    Gerrity, T.R.

    1989-01-01

    The dose of inhaled particles to the respiratory tract depends upon many factors. These factors include the size of the particles, the pattern of breathing (flow and tidal volume), the physical properties of the articles (hygroscopic or non-hygroscopic), anatomy of the respiratory tract, and the pathophysiologic status of the respiratory tract. In addition to these factors, which are primarily related to the deposition of particles, the rate of particle clearance from the respiratory tract also influences the dose of particles. The paper is a review of the various factors influencing dose of inhaled particles to the respiratory tract. The emphasis of the paper is on therapeutic aerosol particles, though the principals discussed also apply to toxic particles as well. An important area of consideration is the influence of disease on the delivery of particle dose. From the point of view of toxic particles this is important when considering potential susceptible populations.

  19. Characteristics of Submicron Aerosols in 2013 summer of Beijing

    NASA Astrophysics Data System (ADS)

    Guo, Song; Hu, Min; Shang, Dongjie; Zheng, Jing; Du, Zhuofei; Wu, Yusheng; Lu, Sihua; Zeng, Limin; Zhang, Renyi

    2016-04-01

    To characterize the air pollution of North China Plain of China, CAREBEIJING-2013 field campaign (Campaigns of Air quality REsearch in BEIJING and surrounding region) was conducted in summer of 2013. Submicron aerosols were measured at an urban site PKU (Peking University, 39° 59'21"N, 116° 18'25"E) from July 28th to September 31st 2013. A suite of integrated instruments was used to measure the size distribution, effective density and hygroscopicity of ambient particles. The chemical composition of submicron particles were measured by using an Aerodyne High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) (Billerica, MA, USA). The average PM2.5 concentration was 73.0±70.7 μg m‑3 during the measurement. The particulate pollution showed distinct 4-7 days cycles controlled by the meteorological conditions. Each cycle started with low PM2.5 mass concentrations (<20 μg m‑3), since the air mass was from relatively clean mountainous area. The particle number concentrations were high, but and the sizes were small (<30 nm) at this stage, which can be explained by the new particle formation. In the succeeding days, both the particle mass and size continuously increased. The PM2.5concentration increased rapidly by >60 μg day‑1, and the particle mean diameter grew to >100 nm. It is interesting to note that the mean diameters showed similar trend to PM2.5 mass concentrations, indicating the particle pollution attributed to the growth of the newly formed small particles. During the measurement, the average particle densities are between 1.3-1.5 g cm‑3, indicating organics and sulfate were dominant in the particles. The densities of smaller particles, i.e. 46 nm, 81nm, showed single peak at 1.3-1.5 g cm‑3, indicating the particles are internal mixed sulfate and organics. While the 150nm and 240 nm particle densities exhibited bimodal distribution with an additional small peak at ˜1.1 g cm‑3, which is considered as external mixed organic

  20. Aerosol Properties over the Eastern North Pacific based on Measurements from the MAGIC Field Campaign

    NASA Astrophysics Data System (ADS)

    Lewis, E. R.; Senum, G.; Springston, S. R.; Kuang, C.

    2015-12-01

    The MAGIC field campaign, funded and operated by the ARM (Atmospheric Radiation Measurement) Climate Research Facility of the US Department of Energy, occurred between September 2012 and October, 2013 aboard the Horizon Lines cargo container ship Spirit making regular trips between Los Angeles, CA and Honolulu, HI. Along this route, which lies very near the GPCI (GCSS Pacific Cross-section Intercomparison) transect, the predominant cloud regime changes from stratocumulus near the California coast to trade-wind cumulus near Hawaii. The transition between these two regimes is poorly understood and not accurately represented in models. The goal of MAGIC was to acquire statistic of this transition and thus improve its representation in models by making repeated transects through this region and measuring properties of clouds and precipitation, aerosols, radiation, and atmospheric structure. To achieve these goals, the Second ARM Mobile Facility (AMF2) was deployed on the Horizon Spirit as it ran its regular route between Los Angeles and Honolulu. AMF2 consists of three 20-foot SeaTainers and includes three radars and other instruments to measure properties of clouds and precipitation; the Aerosol Observing System (AOS), which has a suite of instruments to measure properties of aerosols; and other instruments to measure radiation, meteorological quantities, and sea surface temperature. Two technicians accompanied the AMF2, and scientists rode the ship as observers. MAGIC made nearly 20 round trips between Los Angeles and Honolulu (and thus nearly 40 excursions through the stratocumulus-to-cumulus transition) and spent 200 days at sea, collecting an unprecedented data set. Aerosol properties measured with the AOS include number concentration and size distribution, CCN activity, hygroscopic growth, and light-scattering and absorption. Additionally, more than one hundred filter samples were collected. Aerosol properties and their spatial and temporal behavior are discussed

  1. Aerosol physicochemical properties and implications for visibility during an intense haze episode during winter in Beijing

    NASA Astrophysics Data System (ADS)

    Wang, Y. H.; Liu, Z. R.; Zhang, J. K.; Hu, B.; Ji, D. S.; Yu, Y. C.; Wang, Y. S.

    2015-03-01

    The evolution of physical, chemical and optical properties of urban aerosol particles was characterized during an extreme haze episode in Beijing, PRC, from 24 through 31 January 2013 based on in situ measurements. The average mass concentrations of PM1, PM2.5 and PM10 were 99 ± 67 μg m-3 (average ± SD), 188 ± 128 μg m-3 and 265 ± 157 μg m-3, respectively. A significant increase in PM1-2.5 fraction was observed during the most heavily polluted period. The average scattering coefficient at 550 nm was 877 ± 624 Mm-1. An increasing relative amount of coarse particles can be deduced from the variations of backscattering ratios, asymmetry parameter and scattering Ångström exponent. Particle number-size distributions between 14 and 2500 nm diameter showed high number concentrations, particularly in the nucleation mode and accumulation mode. Size-resolved chemical composition of submicron aerosol from a high-resolution time-of-flight aerosol mass spectrometer showed that the mass concentrations of organic, sulfate, nitrate, ammonium and chlorine mainly resided on particles between 500 and 800 nm (vacu