Intercomparison of cloud condensation nuclei and hygroscopic fraction measurements: Coated soot particles investigated during the LACIS Experiment in November (LExNo)

Snider, Jefferson R.; Wex, Heike; Rose, D.; Kristensson, Adam; Stratmann, Frank; Hennig, T.; Henning, S.; Kiselev, Alexei; Bilde, Merete; Burkhart, Matthew; Dusek, U.; Frank, Göran; Kiendler‐Scharr, Astrid; Mentel, Thomas F.; Petters, M. D.; Pöschl, Ulrich

doi:10.1029/2009jd012618

Cited by 39 publications

(43 citation statements)

References 85 publications

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“…It has long been established that the freshly emitted or less mixed soot particles are of low hygroscopicity, and will not readily act as cloud condensation nuclei (CCN) (Lammel and Novakov, 1995;Weingartner et al, 1997;Dusek et al, 2006;Koehler et al, 2009;Snider et al, 2010). A variety of laboratory studies have been conducted to investigate how coatings or chemical reactions occurring on the soot particle could modify its initial low hygroscopicity to the point where eventually the soot particle could exhibit CCN activity.…”

Section: Introductionmentioning

confidence: 99%

“…A variety of laboratory studies have been conducted to investigate how coatings or chemical reactions occurring on the soot particle could modify its initial low hygroscopicity to the point where eventually the soot particle could exhibit CCN activity. These experiments include investigations on soot from diesel engines (Weingartner et al, 1997;Gysel et al, 2003;Petzold et al, 2005;Tritscher et al, 2011), wood burning Snider et al, 2010) and a variety of flame generators using different chemical fuels (Zuberi et al, 2005;Zhang et al, 2008;Koehler et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

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Ambient black carbon particle hygroscopic properties controlled by mixing state and composition

et al. 2013

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The wet removal of black carbon aerosol (BC) in the atmosphere is a crucial factor in determining its atmospheric lifetime and thereby the vertical and horizontal distributions, dispersion on local and regional scales, and the direct, semi-direct and indirect radiative forcing effects. The in-cloud scavenging and wet deposition rate of freshly emitted hydrophobic BC will be increased on acquisition of more-hydrophilic components by coagulation or coating processes. The lifetime of BC is still subject to considerable uncertainty for most of the model inputs, which is largely due to the insufficient constraints on the BC hydrophobic-to-hydrophilic conversion process from observational field data. This study was conducted at a site along UK North Norfolk coastline, where the BC particles were transported from different regions within Western Europe. A hygroscopicity tandem differential mobility analyser (HTDMA) was coupled with a single particle soot photometer (SP2) to measure the hygroscopic properties of BC particles and associated mixing state in real time. In addition, a Soot Particle AMS (SP-AMS) measured the chemical compositions of additional material associated with BC particles. The ensemble of BC particles persistently contained a less-hygroscopic mode at a growth factor (gf) of around 1.05 at 90% RH (dry diameter 163 nm). Importantly, a more-hygroscopic mode of BC particles was observed throughout the experiment, the gf of these BC particles extended up to ~1.4–1.6 with the minimum between this and the less hygroscopic mode at a gf ~1.25, or equivalent effective hygroscopicity parameter κ ~0.1. The gf of BC particles (gfBC) was highly influenced by the composition of associated soluble material: increases of gfBC were associated with secondary inorganic components, and these increases were more pronounced when ammonium nitrate was in the BC particles; however the presence of secondary organic matter suppressed the gfBC below that of pure inorganics. The Zdanovskii-Stokes-Robinson (ZSR) mixing rule captures the hygroscopicity contributions from different compositions within ±30% compared to the measured results, however is subject to uncertainty due to the complex morphology of BC component and potential artefacts associated with semivolatile particles measured with the HTDMA. This study provides detailed insights on BC hygroscopicity associated with its mixing state, and the results will importantly constrain the microphysical mixing schemes of BC as used by a variety of high level models. In particular, this provides direct evidence to highlight the need to consider ammonium nitrate ageing of BC particles because this will result in particles becoming hydrophilic on much shorter timescales than for sulphate formation, which is often the only mechanism considered

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Ambient black carbon particle hygroscopic properties controlled by mixing state and composition

et al. 2013

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“…This is considerably warmer than the average CCN instrument chamber temperature but is consistent with the standard values for σ s/a given in . Snider et al (2010) show that the particle SS c can be sensitive to the temperature-dependence of σ s/a and recommend using the standard values (as done here) where the temperature-dependence is not accounted for. Size distribution data for N ccn prediction are given by the PCASP but since composition measurements were not taken in flight, a reasonable estimate for the average κ must be used instead.…”

Section: Ccn Closure Attemptmentioning

confidence: 99%

“…Three SS nom settings were used during ISPA-III and correspond to average values for SS eff of 0.22 %, 0.46 % and 0.96 %. The SS eff :SS nom ratio and associated uncertainty are estimated during a chamber calibration in which the activation behavior of size-selected ammonium sulfate particles is tested (Snider et al, 2010). The true chamber SS can be determined from the activation behavior of the ammonium sulfate and a Köhler theory model (Snider et al, 2006).…”

Section: Instruments and Calibrationmentioning

confidence: 99%

Cold and transition season cloud condensation nuclei measurements in western Colorado

Ward

Cotton

2011

Atmos. Chem. Phys.

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Abstract.Recent studies have shown that orographic precipitation and the water resources that depend on it in the Colorado Rocky Mountains are sensitive to the variability of the region's aerosols, whether emitted locally or from distant sources. However, observations of cloud droplet nucleating aerosols in western Colorado, climatologically upwind of the Colorado Rocky Mountains, have been limited to a few studies at a single, northern site. To address this knowledge gap, atmospheric aerosols were sampled at a ground site in southwestern Colorado and in low-level north to south transects of the Colorado Western Slope as part of the Inhibition of Snowfall by Pollution Aerosols (ISPA-III) field campaign. Total particle and cloud condensation nuclei (CCN) number concentrations were measured for a 24-day period in Mesa Verde National Park, in September and October 2009. Regression analysis showed a positive relationship between mid-troposphere atmospheric pressure to the west of the site and the total particle count at the ground site, but no similar statistically significant relationship was found for the observed CCN. These data were supplemented with particle and CCN number concentration, as well as particle size distribution measurements collected aboard the King Air platform during December 2009. A CCN closure attempt was performed and suggested that the sampled aerosol may have had a low hygroscopicity that changed little with the largescale wind direction. Together, the sampled aerosols from these field programs were characteristic of a rural continental environment with CCN number concentrations that varied slowly in time, and little in space along the Western Slope.

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“…Here, BC is quantified by the ability of a material to absorb energy at a 670 nm wavelength. BC aerosol is often considered water-insoluble when freshly emitted but can add water-soluble materials in surface oxidation and condensation reactions during its atmospheric lifetime (Cooke and Wilson 1996;Koehler et al 2009;Snider et al 2010;McMeeking et al 2011). Hence, as a BC particle ages, the particle can modify its overall water-insoluble fraction, hygroscopic properties, and reduce the critical watervapor saturation required to initiate heterogeneous nucleation (Zhang et al 2008).…”

Section: Introductionmentioning

confidence: 99%

A Unique Online Method to Infer Water-Insoluble Particle Contributions

Short

Giordano

Zhu

et al. 2014

Aerosol Science and Technology

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Particle number, size, and composition information is important for constraining aerosol effects on air quality, climate, and health. The composition of particles, especially from vehicular sources, may contain insoluble black carbon (BC) materials that modify particle nucleating properties. In this study, we develop a method to provide quantitative and real-time information on the water-insoluble components found in nearroad aerosol sources. A water-based condensation particle counter (W-CPC) and a butanol-based CPC (B-CPC) were used to measure the particle number concentration. Both instruments were coupled with a scanning mobility particle sizer (SMPS) to record the particle number and size data. Real time waterinsoluble particle mass was estimated from the difference in particle number concentration between the two CPCs; theoretical water-insoluble mass was calculated from the ideal hygroscopicity single parameter k-values. This online method was calibrated with test compounds and then applied to data collected from a field study. Ambient aerosol was sampled from a monitoring station located 15 m from the I-710 freeway in Long Beach, California. The results show that near-roadway emissions contain water-insoluble (BC and non-BC) components. Particle number and BC concentrations increase after changes in wind direction near the freeway on both weekday and weekend measurements. Particles were less hygroscopic (k 0.2) before changes in wind direction from downwind to upwind of the freeway (k > 0.6). Rapid changes in water-solubility can be captured with this technique. By assuming a two-component mixture, the water-insoluble mass fractions were inferred. BC shows a positive correlation with the water-insoluble mass however its presence may not account for the entire waterinsoluble mass from the near-roadway source.

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Intercomparison of cloud condensation nuclei and hygroscopic fraction measurements: Coated soot particles investigated during the LACIS Experiment in November (LExNo)

Cited by 39 publications

References 85 publications

Ambient black carbon particle hygroscopic properties controlled by mixing state and composition

Ambient black carbon particle hygroscopic properties controlled by mixing state and composition

Cold and transition season cloud condensation nuclei measurements in western Colorado

A Unique Online Method to Infer Water-Insoluble Particle Contributions

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