scispace - formally typeset
Search or ask a question
Journal ArticleDOI

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

27 Jan 2015-Journal of Geophysical Research (John Wiley & Sons, Ltd)-Vol. 120, Iss: 2, pp 766-783
TL;DR: In this article, the effects of chemical composition (bulk and size resolved) and mixing state (internal and external) on CCN activity of aerosols were investigated during the winter season in Kanpur.
Abstract: 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
Citations
More filters
Journal ArticleDOI
TL;DR: Aerosol and CCN number concentrations, and aerosol size distributions in and around the Korean Peninsula were measured onboard the NASA DC-8 research aircraft during the KORUS-AQ campaign in May and June of 2016 as discussed by the authors.

10 citations

Journal ArticleDOI
TL;DR: In this article, the authors analyzed the significant spatial variability in the aerosol spectrum, cloud condensation nuclei (CCN) activation characteristics, and the cloud droplet spectral properties over a coastal and an inland location.

10 citations

Journal ArticleDOI
TL;DR: In this paper, a positive matrix factorization (PMF) method was used to analyze the aerosol size distribution and cloud condensation nuclei (CCN) number concentrations over the Yellow Sea on board the research vessel Gisang 1.

10 citations

Journal ArticleDOI
TL;DR: A detailed time-resolved chemical characterization and volatility study of winter time ambient non refractory submicron aerosols (NR-PM 1 ) was conducted at Kanpur, a polluted city of India as discussed by the authors.

9 citations


Cites background or methods or result from "CCN closure study: Effects of aeros..."

  • ...%) to the observed NR PM1 loading (143± 40 µg/m3) in line with other studies at this location (Bhattu & Tripathi, 2015; Chakraborty et al., 2015; Kaul, Gupta, Tripathi, Tare, & Collett, 2011; Tare et al., 2006)....

    [...]

  • ...For ambient data set, a CE amb (collection efficiency) value of 0.5 is used in this study, similar to what has been reported in other AMS studies at the same location (Bhattu & Tripathi, 2015; Chakraborty et al., 2015; Shamjad et al., 2015)....

    [...]

  • ...NR PM1 mass concentration is well within the range of previously reported PM1 values (100–530 µg/m3) at this location (Bhattu & Tripathi, 2015; Gupta & Mandariya, 2013; Kaul, Gupta, & Tripathi, 2012, 2011; Tare et al., 2006)....

    [...]

25 Jan 2017
TL;DR: In this paper, the mixing state index (χ) was used to quantify the degree of external and internal mixing of aerosol populations, and combined with particle-resolved model simulations to quantify error in predicted cloud condensation nuclei (CCN) predictions when mixing state information is neglected.
Abstract: Abstract. It is commonly assumed that models are more prone to errors in predicted cloud condensation nuclei (CCN) concentrations when the aerosol populations are externally mixed. In this work we investigate this assumption by using the mixing state index (χ) proposed by Riemer and West (2013) to quantify the degree of external and internal mixing of aerosol populations. We combine this metric with particle-resolved model simulations to quantify error in CCN predictions when mixing state information is neglected, exploring a range of scenarios that cover different conditions of aerosol aging. We show that mixing state information does indeed become unimportant for more internally mixed populations, more precisely for populations with χ larger than 75 %. For more externally mixed populations (χ below 20 %) the relationship of χ and the error in CCN predictions is not unique and ranges from lower than −40 % to about 150 %, depending on the underlying aerosol population and the environmental supersaturation. We explain the reasons for this behavior with detailed process analyses.

9 citations


Cites background from "CCN closure study: Effects of aeros..."

  • ...In this study we focus on CCN activity, and indeed, many CCN closure studies show that the quality of the closure depends crucially on the assumptions about aerosol mixing state (McFiggans et al., 2006; Wang et al., 2010; Bhattu and Tripathi, 2015; Ervens et al., 2010)....

    [...]

References
More filters
Journal ArticleDOI
24 Jan 1992-Science
TL;DR: The aerosol forcing has likely offset global greenhouse warming to a substantial degree, however, differences in geographical and seasonal distributions of these forcings preclude any simple compensation.
Abstract: Although long considered to be of marginal importance to global climate change, tropospheric aerosol contributes substantially to radiative forcing, and anthropogenic sulfate aerosol in particular has imposed a major perturbation to this forcing. Both the direct scattering of shortwavelength solar radiation and the modification of the shortwave reflective properties of clouds by sulfate aerosol particles increase planetary albedo, thereby exerting a cooling influence on the planet. Current climate forcing due to anthropogenic sulfate is estimated to be –1 to –2 watts per square meter, globally averaged. This perturbation is comparable in magnitude to current anthropogenic greenhouse gas forcing but opposite in sign. Thus, the aerosol forcing has likely offset global greenhouse warming to a substantial degree. However, differences in geographical and seasonal distributions of these forcings preclude any simple compensation. Aerosol effects must be taken into account in evaluating anthropogenic influences on past, current, and projected future climate and in formulating policy regarding controls on emission of greenhouse gases and sulfur dioxide. Resolution of such policy issues requires integrated research on the magnitude and geographical distribution of aerosol climate forcing and on the controlling chemical and physical processes.

3,413 citations


"CCN closure study: Effects of aeros..." refers background in this paper

  • ...Atmospheric aerosols indirectly affect the global energy budget by acting as cloud condensation nuclei (CCN) [Charlson et al., 1992]....

    [...]

Journal ArticleDOI
TL;DR: In this article, an overview of the atmospheric degradation mechanisms for SOA precursors, gas-particle partitioning theory and analytical techniques used to determine the chemical composition of SOA is presented.
Abstract: Secondary organic aerosol (SOA) accounts for a significant fraction of ambient tropospheric aerosol and a detailed knowledge of the formation, properties and transformation of SOA is therefore required to evaluate its impact on atmospheric processes, climate and human health. The chemical and physical processes associated with SOA formation are complex and varied, and, despite considerable progress in recent years, a quantitative and predictive understanding of SOA formation does not exist and therefore represents a major research challenge in atmospheric science. This review begins with an update on the current state of knowledge on the global SOA budget and is followed by an overview of the atmospheric degradation mechanisms for SOA precursors, gas-particle partitioning theory and the analytical techniques used to determine the chemical composition of SOA. A survey of recent laboratory, field and modeling studies is also presented. The following topical and emerging issues are highlighted and discussed in detail: molecular characterization of biogenic SOA constituents, condensed phase reactions and oligomerization, the interaction of atmospheric organic components with sulfuric acid, the chemical and photochemical processing of organics in the atmospheric aqueous phase, aerosol formation from real plant emissions, interaction of atmospheric organic components with water, thermodynamics and mixtures in atmospheric models. Finally, the major challenges ahead in laboratory, field and modeling studies of SOA are discussed and recommendations for future research directions are proposed.

3,324 citations


"CCN closure study: Effects of aeros..." refers background in this paper

  • ...…of aerosols (10–70% of the submicron mass of the ambient aerosols), their formation mechanisms, detailed speciation, and roles in influencing the Earth’s radiation budget are still not well understood [Saxena and Hildemann, 1996; Turpin et al., 2000; Hallquist et al., 2009; Kanakidou et al., 2005]....

    [...]

Journal ArticleDOI
11 Dec 2009-Science
TL;DR: 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 is presented, which can serve as a basis for improving parameterizations in regional and global models.
Abstract: 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.

3,104 citations


"CCN closure study: Effects of aeros..." refers background or methods in this paper

  • ...…better closure results obtained are unexpected because atmospheric processes, such as coagulation, gas condensation, and photochemical transformation, will shift these aerosols to an internally mixed state [Moore et al., 2011; De Gouw and Jimenez, 2009; Jimenez et al., 2009; Shamjad et al., 2012]....

    [...]

  • ...The rapidly evolving and transforming nature of organics in polluted urban and semiurban regions around the globe demand temporally resolved and size-resolved chemical composition measurements to account for the role of organic aerosols in CCN activity [Jimenez et al., 2009; Ng et al., 2011]....

    [...]

  • ...The O:C ratio is the best representation of the degree of oxygenation [Jimenez et al., 2009; Aiken et al., 2008]....

    [...]

  • ...Even after considerable efforts, the dependence of aerosol hygroscopicity on the degree of oxygenation under subsaturated and supersaturated conditions is not well understood [Jimenez et al., 2009; Chang et al., 2010; Juranyi et al., 2009]....

    [...]

Journal ArticleDOI
TL;DR: In this article, the authors reviewed existing knowledge with regard to organic aerosol (OA) of importance for global climate modelling and defined critical gaps needed to reduce the involved uncertainties, and synthesized the information to provide a continuous analysis of the flow from the emitted material to the atmosphere up to the point of the climate impact of the produced organic aerosols.
Abstract: The present paper reviews existing knowledge with regard to Organic Aerosol (OA) of importance for global climate modelling and defines critical gaps needed to reduce the involved uncertainties. All pieces required for the representation of OA in a global climate model are sketched out with special attention to Secondary Organic Aerosol (SOA): The emission estimates of primary carbonaceous particles and SOA precursor gases are summarized. The up-to-date understanding of the chemical formation and transformation of condensable organic material is outlined. Knowledge on the hygroscopicity of OA and measurements of optical properties of the organic aerosol constituents are summarized. The mechanisms of interactions of OA with clouds and dry and wet removal processes parameterisations in global models are outlined. This information is synthesized to provide a continuous analysis of the flow from the emitted material to the atmosphere up to the point of the climate impact of the produced organic aerosol. The sources of uncertainties at each step of this process are highlighted as areas that require further studies.

2,863 citations

Journal ArticleDOI
TL;DR: In this paper, a method to describe the relationship between particle dry diameter and cloud condensation activity using a single hygroscopicity parameter is presented. But this method is limited to single and multi-component particles with varying amounts of inorganic, organic and surface active compounds.
Abstract: We present a method to describe the relationship between particle dry diameter and cloud condensation nu- clei (CCN) activity using a single hygroscopicity parameter . Values of the hygroscopicity parameter are between 0.5 and 1.4 for highly-CCN-active salts such as sodium chlo- ride, between 0.01 and 0.5 for slightly to very hygroscopic organic species, and 0 for nonhygroscopic components. Ob- servations indicate that atmospheric particulate matter is typ- ically characterized by 0.1<< 0.9. If compositional data are available and if the hygroscopicity parameter of each com- ponent is known, a multicomponent hygroscopicity parame- ter can be computed by weighting component hygroscopic- ity parameters by their volume fractions in the mixture. In the absence of information on chemical composition, exper- imental data for complex, multicomponent particles can be fitted to obtain the hygroscopicity parameter. The hygroscop- icity parameter can thus also be used to conveniently model the CCN activity of atmospheric particles, including those containing insoluble components. We confirm the applica- bility of the hygroscopicity parameter and its mixing rule by applying it to published hygroscopic diameter growth fac- tor and CCN-activation data for single- and multi-component particles containing varying amounts of inorganic, organic and surface active compounds. We suggest that may be fit to CCN data assuming s/a=0.072 J m 2 and present a table of derived for this value and T=298.15 K. The predicted hygroscopicities for mixtures that contain the surfactant ful- vic acid agree within uncertainties with the measured values. It thus appears that this approach is adequate for predict- ing CCN activity of mixed particles containing surface ac- tive materials, but the generality of this assumption requires further verification.

2,011 citations

Related Papers (5)