Cloud condensation nuclei closure during the International Consortium for Atmospheric Research on Transport and Transformation 2004 campaign: Effects of size‐resolved composition

Medina, Jeessy; Nenes, Athanasios; Sotiropoulou, Rafaella–Eleni P.; Cottrell, L.; Ziemba, L. D.; Beckman, P.; Griffin, Robert J.

doi:10.1029/2006jd007588

Cited by 127 publications

(168 citation statements)

References 45 publications

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“…This difference may identify a separation between fresh and aged aerosols in terms of diversity. This result and the experimental method could be useful for climate models, allowing an experimental mixing state and size-resolved particle composition to be used rather than assumed to improve model performance [78][79][80]. Even though this type of individual particle microscopy study is time-consuming, regions that are important to global climate models (such as the Amazon) may benefit from the improved accuracy of an experimentally determined mixing state.…”

Section: Discussionmentioning

confidence: 99%

Elemental Mixing State of Aerosol Particles Collected in Central Amazonia during GoAmazon2014/15

et al. 2017

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Two complementary techniques, Scanning Transmission X-ray Microscopy/Near Edge Fine Structure spectroscopy (STXM/NEXAFS) and Scanning Electron Microscopy/Energy Dispersive X-ray spectroscopy (SEM/EDX), have been quantitatively combined to characterize individual atmospheric particles. This pair of techniques was applied to particle samples at three sampling sites (ATTO, ZF2, and T3) in the Amazon basin as part of the Observations and Modeling of the Green Ocean Amazon (GoAmazon2014/5) field campaign during the dry season of 2014. The combined data was subjected to k-means clustering using mass fractions of the following elements: C, N, O, Na, Mg, P, S, Cl, K, Ca, Mn, Fe, Ni, and Zn. Cluster analysis identified 12 particle types across different sampling sites and particle sizes. Samples from the remote Amazon Tall Tower Observatory (ATTO, also T0a) exhibited less cluster variety and fewer anthropogenic clusters than samples collected at the sites nearer to the Manaus metropolitan region, ZF2 (also T0t) or T3. Samples from the ZF2 site contained aged/anthropogenic clusters not readily explained by transport from ATTO or Manaus, possibly suggesting the effects of long range atmospheric transport or other local aerosol sources present during sampling. In addition, this data set allowed for recently established diversity parameters to be calculated. All sample periods had high mixing state indices (χ) that were >0.8. Two individual particle diversity (D i ) populations were observed, with particles <0.5 µm having a D i of~2.4 and >0.5 µm particles having a D i of~3.6, which likely correspond to fresh and aged aerosols, respectively. The diversity parameters determined by the quantitative method presented here will serve to aid in the accurate representation of aerosol mixing state, source apportionment, and aging in both less polluted and more developed environments in the Amazon Basin.

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Section: Discussionmentioning

confidence: 99%

Elemental Mixing State of Aerosol Particles Collected in Central Amazonia during GoAmazon2014/15

et al. 2017

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“…Therefore, coupled measurements of an AMS and the Hygroscopicity Tandem Differential Mobility Analyzer (H-TDMA) are able to capture highly variable changes in chemical particle composition and hygroscopicity in real time. Some studies have highlighted the advantage of using size-selected AMS information over size-averaged information from offline chemical characterization (Medina et al, 2007;Gunthe et al, 2009;Cerully et al, 2011;Wu et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2016

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Abstract. 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 PM 1 . 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 PM 2.5 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 PM 2.5 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 hightime-resolution size-resolved chemical composition derived from aerosol mass spectrometer (AMS) measurements using the Zdanovskii-Stokes-Robinson (ZSR) mixing rule. The organic hygroscopicity parameter (κ org ) 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.

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“…In addition, the identification and characterization of submicron organic aerosol sources has been performed in this study. Previous CCN-based closure studies have been limited by assumptions regarding the solubility of organics, i.e., organics are assumed to be completely soluble, completely insoluble or to have defined fractions of soluble and insoluble components, which may not be applicable for urban locations [Medina et al, 2007;Broekhuizen et al, 2006;Chang et al, 2007;Srivastava et al, 2013]. WSOCs affect the CCN concentration by decreasing the critical diameter obtained from the Köhler theory.…”

Section: Introductionmentioning

confidence: 99%

CCN closure study: Effects of aerosol chemical composition and mixing state

Bhattu

Tripathi

2015

JGR Atmospheres

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This study presents a detailed cloud condensation nuclei (CCN) closure study that investigates the effects of chemical composition (bulk and size resolved) and mixing state (internal and external) on CCN activity of aerosols. Measurements of the chemical composition, aerosol size distribution, total number concentration, and CCN concentration at supersaturation (SS = 0.2–1.0%) were performed during the winter season in Kanpur, India. Among the two cases considered here, better closure results are obtained for case 1 (low total aerosol loading, 49.54 ± 26.42 μg m−3, and high O:C ratio, 0.61 ±0.07) compared to case 2 (high total aerosol loading, 101.05 ± 18.73 μg m−3, and low O:C ratio, 0.42 ±0.06), with a maximum reduction of 3–81% in CCN overprediction for all depleted SS values (0.18–0.60%). Including the assumption that less volatile oxidized organic aerosols represent the soluble organic fraction reduced the overprediction to at most 40% and 129% in the internal and external mixing scenarios, respectively. At higher depleted SS values (0.34–0.60%), size‐resolved chemical composition with an internal mixing state performed well in CCN closure among all organic solubility scenarios. However, at a lower depleted SS value (0.18%), closure is found to be more sensitive to both the chemical composition and mixing state of aerosols. At higher SS values, information on the solubility of organics and size‐resolved chemical composition is required for accurate CCN predictions, whereas at lower SS values, information on the mixing state in addition to the solubility of organics and size‐resolved chemical composition is required. Overall, κtotal values are observed to be independent of the O:C ratio [κtotal= (0.36 ±0.01) × O:C − (0.03 ± 0.01)] in the range of 0.2

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Cloud condensation nuclei closure during the International Consortium for Atmospheric Research on Transport and Transformation 2004 campaign: Effects of size‐resolved composition

Cited by 127 publications

References 45 publications

Elemental Mixing State of Aerosol Particles Collected in Central Amazonia during GoAmazon2014/15

Elemental Mixing State of Aerosol Particles Collected in Central Amazonia during GoAmazon2014/15

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

CCN closure study: Effects of aerosol chemical composition and mixing state

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