scholarly journals Resolving the mechanisms of hygroscopic growth and cloud condensation nuclei activity for organic particulate matter

2018 ◽  
Vol 9 (1) ◽  
Author(s):  
Pengfei Liu ◽  
Mijung Song ◽  
Tianning Zhao ◽  
Sachin S. Gunthe ◽  
Suhan Ham ◽  
...  
Keyword(s):  
Particulate Matter ◽  
Cloud Condensation Nuclei ◽  
Hygroscopic Growth ◽  
Condensation Nuclei ◽  
Organic Particulate Matter

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

2011 ◽  
Vol 11 (24) ◽  
pp. 12627-12645 ◽  
Author(s):  
J. H. Kim ◽  
S. S. Yum ◽  
S. Shim ◽  
S.-C. Yoon ◽  
J. G. Hudson ◽  
...  
Keyword(s):  
Korean Peninsula ◽  
Total Concentration ◽  
Cloud Condensation Nuclei ◽  
Geometric Mean ◽  
Aerosol Size Distribution ◽  
Monitoring Site ◽  
Hygroscopic Growth ◽  
Condensation Nuclei ◽  
Critical Supersaturation ◽  
Better Than

Abstract. 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-resolved hygroscopicity information from the HTDMA was used, for which the average relative deviations from the measured values were 28 ± 20% for 0.2% S (mostly under-prediction), 25 ± 52% for 0.6% (balanced between over- and under-prediction) and 19 ± 15% for 1.0% S (balanced). Prescribing a constant hygroscopicity parameter suggested in the literature (κ = 0.3) for all sizes and times resulted in average relative deviations of 28–41% where over-prediction was dominant. When constant hygroscopicity was assumed, the relative deviation tended to increase with decreasing NCCN, which was accompanied by an increase of the sub-100 nm fraction. These results suggest that hygroscopicity information for particles of diameters smaller than 100 nm is crucial for more accurate predictions of NCCN. For confirmation when κ = 0.17, the average κ for sub-100 nm particles in this study, was applied for sub-100 nm and κ = 0.3 for all other sizes, the CCN closure became significantly better than that with κ = 0.3 for all sizes.

scholarly journals Physical properties of the sub-micrometer aerosol over the Amazon rain forest during the wet-to-dry season transition - comparison of modeled and measured CCN concentrations

2004 ◽  
Vol 4 (8) ◽  
pp. 2119-2143 ◽  
Author(s):  
J. Rissler ◽  
E. Swietlicki ◽  
J. Zhou ◽  
G. Roberts ◽  
M. O. Andreae ◽  
...  
Keyword(s):  
Size Distribution ◽  
Biomass Burning ◽  
Time Resolution ◽  
Large Scale ◽  
Transition Period ◽  
Cloud Condensation Nuclei ◽  
Particle Diameter ◽  
Hygroscopic Growth ◽  
Condensation Nuclei ◽  
Number Size Distribution

Abstract. Sub-micrometer atmospheric aerosol particles were studied in the Amazon region, 125 km northeast of Manaus, Brazil (-1°55.2'S, 59°28.1'W). The measurements were performed during the wet-to-dry transition period, 4-28 July 2001 as part of the LBA (Large-Scale Biosphere Atmosphere Experiment in Amazonia) CLAIRE-2001 (Cooperative LBA Airborne Regional Experiment) experiment. The number size distribution was measured with two parallel differential mobility analyzers, the hygroscopic growth at 90% RH with a Hygroscopic Tandem Mobility Analyzer (H-TDMA) and the concentrations of cloud condensation nuclei (CCN) with a cloud condensation nuclei counter. A model was developed that uses the H-TDMA data to predict the number of soluble molecules or ions in the individual particles and the corresponding minimum particle diameter for activation into a cloud droplet at a certain supersaturation. Integrating the number size distribution above this diameter, CCN concentrations were predicted with a time resolution of 10 min and compared to the measured concentrations. During the study period, three different air masses were identified and compared: clean background, air influenced by aged biomass burning, and moderately polluted air from recent local biomass burning. For the clean period 2001, similar number size distributions and hygroscopic behavior were observed as during the wet season at the same site in 1998, with mostly internally mixed particles of low diameter growth factor (~1.3 taken from dry to 90% RH). During the periods influenced by biomass burning the hygroscopic growth changed slightly, but the largest difference was seen in the number size distribution. The CCN model was found to be successful in predicting the measured CCN concentrations, typically within 25%. A sensitivity study showed relatively small dependence on the assumption of which model salt that was used to predict CCN concentrations from H-TDMA data. One strength of using H-TDMA data to predict CCN concentrations is that the model can also take into account soluble organic compounds, insofar as they go into solution at 90% RH. Another advantage is the higher time resolution compared to using size-resolved chemical composition data.

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

2011 ◽  
Vol 11 (7) ◽  
pp. 19683-19727 ◽  
Author(s):  
J. H. Kim ◽  
S. S. Yum ◽  
S. Shim ◽  
S.-C. Yoon ◽  
J. G. Hudson ◽  
...  
Keyword(s):  
Size Distribution ◽  
Total Concentration ◽  
Cloud Condensation Nuclei ◽  
Geometric Mean ◽  
Aerosol Size Distribution ◽  
Monitoring Site ◽  
Hygroscopic Growth ◽  
Condensation Nuclei ◽  
Critical Supersaturation ◽  
Aerosol Hygroscopicity

Abstract. 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 HTDMA was used, for which the average relative deviations from the measured values were 19 % for 1.0 % S and 28 % for 0.2 % S. Prescribing a constant hygroscopicity parameter suggested in literature (κ = 0.3) for all sizes and time resulted in the average relative deviations, 25–40 %. When constant hygroscopicity was assumed, the relative deviation tended to increase with decreasing NCCN, which was accompanied by increase of sub-100 nm fraction. These results suggest that hygroscopicity information for aerosols of diameters smaller than 100 nm is crucial for more accurate prediction of NCCN.

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

2013 ◽  
Vol 13 (1) ◽  
pp. 2035-2075 ◽  
Author(s):  
Z. Jurányi ◽  
T. Tritscher ◽  
M. Gysel ◽  
M. Laborde ◽  
L. Gomes ◽  
...  
Keyword(s):  
Water Uptake ◽  
Cloud Condensation Nuclei ◽  
Pure Water ◽  
Particle Diameter ◽  
Complex Mixture ◽  
Average Particle ◽  
Hygroscopic Growth ◽  
Condensation Nuclei ◽  
Mixing State ◽  
Ambient Aerosols

Abstract. 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 the 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.%. 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 coupled with the HTDMA and closure was achieved over the whole range of probed dry diameters, growth factors and supersaturations using the κ-parameterisation 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. Very good agreement was found at all supersaturations which shows that monodisperse CCN measurements are a reliable alternative to determine the hygroscopic mixing state of ambient aerosols.

scholarly journals Water uptake of subpollen aerosol particles: hygroscopic growth, cloud condensation nuclei activation, and liquid–liquid phase separation

2021 ◽  
Vol 21 (9) ◽  
pp. 6999-7022
Author(s):  
Eugene F. Mikhailov ◽  
Mira L. Pöhlker ◽  
Kathrin Reinmuth-Selzle ◽  
Sergey S. Vlasenko ◽  
Ovid O. Krüger ◽  
...  
Keyword(s):  
Phase Separation ◽  
Liquid Phase ◽  
Water Uptake ◽  
Cloud Condensation Nuclei ◽  
Liquid Phase Separation ◽  
Hygroscopic Growth ◽  
Differential Mobility Analyzer ◽  
Condensation Nuclei ◽  
Differential Mobility ◽  
Liquid Liquid Phase Separation

Abstract. Pollen grains emitted from vegetation can release subpollen particles (SPPs) that contribute to the fine fraction of atmospheric aerosols and may act as cloud condensation nuclei (CCN), ice nuclei (IN), or aeroallergens. Here, we investigate and characterize the hygroscopic growth and CCN activation of birch, pine, and rapeseed SPPs. A high-humidity tandem differential mobility analyzer (HHTDMA) was used to measure particle restructuring and water uptake over a wide range of relative humidity (RH) from 2 % to 99.5 %, and a continuous flow CCN counter was used for size-resolved measurements of CCN activation at supersaturations (S) in the range of 0.2 % to 1.2 %. For both subsaturated and supersaturated conditions, effective hygroscopicity parameters, κ, were obtained by Köhler model calculations. Gravimetric and chemical analyses, electron microscopy, and dynamic light scattering measurements were performed to characterize further properties of SPPs from aqueous pollen extracts such as chemical composition (starch, proteins, DNA, and inorganic ions) and the hydrodynamic size distribution of water-insoluble material. All investigated SPP samples exhibited a sharp increase of water uptake and κ above ∼95 % RH, suggesting a liquid–liquid phase separation (LLPS). The HHTDMA measurements at RH >95 % enable closure between the CCN activation at water vapor supersaturation and hygroscopic growth at subsaturated conditions, which is often not achieved when hygroscopicity tandem differential mobility analyzer (HTDMA) measurements are performed at lower RH where the water uptake and effective hygroscopicity may be limited by the effects of LLPS. Such effects may be important not only for closure between hygroscopic growth and CCN activation but also for the chemical reactivity, allergenic potential, and related health effects of SPPs.

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

2012 ◽  
Vol 12 (18) ◽  
pp. 8575-8587 ◽  
Author(s):  
B. J. Murray ◽  
A. E. Haddrell ◽  
S. Peppe ◽  
J. F. Davies ◽  
J. P. Reid ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Acid Solution ◽  
Marine Boundary Layer ◽  
Fine Particles ◽  
Cloud Condensation Nuclei ◽  
Amorphous Material ◽  
Amorphous State ◽  
Hygroscopic Growth ◽  
Condensation Nuclei ◽  
Iodic Acid

Abstract. 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 factors observed in previous experiments.

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

2015 ◽  
Vol 15 (12) ◽  
pp. 17317-17365 ◽  
Author(s):  
A. M. K. Hansen ◽  
J. Hong ◽  
T. Raatikainen ◽  
K. Kristensen ◽  
A. Ylisirniö ◽  
...  
Keyword(s):  
Surface Tension ◽  
Ammonium Sulfate ◽  
Cloud Condensation Nuclei ◽  
Pure Water ◽  
Droplet Surface ◽  
Chemical Compositions ◽  
Hygroscopic Growth ◽  
Condensation Nuclei ◽  
Hygroscopic Properties ◽  
Wide Range

Abstract. 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 measurements were compared with κ calculated applying the volume additive Zdanovskii–Stokes–Robinson mixing rule, as well as κ modelled from equilibrium Köhler theory with different assumptions regarding L-OS 250 bulk-to-surface partitioning and aqueous droplet surface tension. This study is to our knowledge the first to investigate the hygroscopic properties and surface activity of L-OS 250; hence it is an important first step towards understanding the atmospheric impact of organosulfates.

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