scholarly journals Classifying organic materials by oxygen-to-carbon elemental ratio to predict the activation regime of Cloud Condensation Nuclei (CCN)

2013 ◽  
Vol 13 (10) ◽  
pp. 5309-5324 ◽  
Author(s):  
M. Kuwata ◽  
W. Shao ◽  
R. Lebouteiller ◽  
S. T. Martin
Keyword(s):  
Organic Compounds ◽  
Organic Materials ◽  
Cloud Condensation Nuclei ◽  
Life Cycles ◽  
Condensation Nuclei ◽  
Elemental Ratio ◽  
Organic Components ◽  
Activation Data ◽  
The Difference ◽  
Activation Behavior

Abstract. The governing highly soluble, slightly soluble, or insoluble activation regime of organic compounds as cloud condensation nuclei (CCN) was examined as a function of oxygen-to-carbon elemental ratio (O : C). New data were collected for adipic, pimelic, suberic, azelaic, and pinonic acids. Secondary organic materials (SOMs) produced by α-pinene ozonolysis and isoprene photo-oxidation were also included in the analysis. The saturation concentrations C of the organic compounds in aqueous solutions served as the key parameter for delineating regimes of CCN activation, and the values of C were tightly correlated to the O : C ratios. The highly soluble, slightly soluble, and insoluble regimes of CCN activation were found to correspond to ranges of [O : C] > 0.6, 0.2 < [O : C] < 0.6, and [O : C] < 0.2, respectively. These classifications were evaluated against CCN activation data of isoprene-derived SOM (O : C = 0.69–0.72) and α-pinene-derived SOM (O : C = 0.38–0.48). Isoprene-derived SOM had highly soluble activation behavior, consistent with its high O : C ratio. For α-pinene-derived SOM, although CCN activation can be modeled as a highly soluble mechanism, this behavior was not predicted by the O : C ratio, for which a slightly soluble mechanism was anticipated. Complexity in chemical composition, resulting in continuous water uptake and the absence of a deliquescence transition that can thermodynamically limit CCN activation, might explain the difference in the behavior of α-pinene-derived SOM compared to that of pure organic compounds. The present results suggest that atmospheric particles dominated by hydrocarbon-like organic components do not activate (i.e., insoluble regime) whereas those dominated by oxygenated organic components activate (i.e., highly soluble regime) for typical atmospheric cloud life cycles.

scholarly journals Classifying organic materials by oxygen-to-carbon elemental ratio to predict the activation regime of cloud condensation nuclei (CCN)

2012 ◽  
Vol 12 (12) ◽  
pp. 31829-31870 ◽  
Author(s):  
M. Kuwata ◽  
W. Shao ◽  
R. Lebouteiller ◽  
S. T. Martin
Keyword(s):  
Organic Compounds ◽  
Organic Materials ◽  
Cloud Condensation Nuclei ◽  
Condensation Nuclei ◽  
Photo Oxidation ◽  
Elemental Ratio ◽  
Organic Components ◽  
Activation Data ◽  
Activation Behavior ◽  
Key Parameter

Abstract. The governing highly soluble, slightly soluble, or insoluble activation regime of organic compounds as cloud condensation nuclei (CCN) was examined as a function of oxygen-to-carbon elemental ratio (O : C). New data were collected for adipic, pimelic, suberic, azelaic and pinonic acids. Secondary organic materials (SOMs) produced by α-pinene ozonolysis and isoprene photo-oxidation were also included in the analysis. The saturation concentrations C of the organic compounds in aqueous solutions served as the key parameter for delineating regimes of CCN activation, and the values of C were tightly correlated to the O : C ratios. The highly soluble, slightly soluble, and insoluble regimes of CCN activation were found to correspond to ranges of [O : C] > 0.6, 0.2 < [O : C] < 0.6, and [O : C] < 0.2, respectively. These classifications were evaluated against CCN activation data of isoprene-derived SOM (O : C = 0.69–0.72) and α-pinene-derived SOM (O : C = 0.38–0.48). Isoprene-derived SOM had highly soluble activation behavior, consistent with its high O : C ratio. For α-pinene-derived SOM, although CCN activation can be modeled as a highly soluble mechanism, this behavior was not predicted by the O : C ratio, for which a slightly soluble mechanism was anticipated. Complexity in chemical composition, resulting in continuous water uptake and the absence of a deliquescence transition that can thermodynamically limit CCN activation, might explain the differences of α-pinene-derived SOM compared to the behavior of pure organic compounds. The present results suggest that atmospheric particles dominated by hydrocarbon-like organic components do not activate (i.e. insoluble regime) whereas those dominated by oxygenated organic components activate (i.e. highly soluble regime).

Evaluation of wastewater characterization methods

2005 ◽  
Vol 52 (10-11) ◽  
pp. 61-68 ◽  
Author(s):  
E.-H. Choi ◽  
B. Klapwijk ◽  
A. Mels ◽  
H. Brouwer
Keyword(s):  
Organic Matter ◽  
Organic Compounds ◽  
Nitrate Concentration ◽  
Characterization Methods ◽  
Biochemical Characteristics ◽  
Organic Components ◽  
N Removal ◽  
Curve Fit ◽  
The Difference

Wastewater contains various organic components with different physical and biochemical characteristics. ASM No. 1 distinguishes two categories of biodegradable organic matter in wastewater, rapidly and slowly biodegradable. In general there are two methods for wastewater characterization: based on filtration in combination with a long-term BOD test or based on a respirogram. By comparing both approaches, we showed that in wastewater three categories of organic compounds with different biodegradation rates can be distinguished. These categories are referred to as readily biodegradable, rapidly hydrolysable and slowly hydrolysable organic matter. The total biodegradable COD can be found from a long-term BOD-test combined with a curve-fit and the readily biodegradable and rapidly hydrolysable from a respirogram. The slowly hydrolysable is the difference between total biodegradable COD and the sum of readily biodegradable and rapidly hydrolysable COD. Simulation with characterization based on filtration for a pre-anoxic reactor with a certain N-removal compared with the N-removal of the same plant with wastewater according to the modified characterization shows different results of each wastewater, especially with regard to the effluent nitrate concentration.

scholarly journals Comment on Kokkola et al. (2008) – Comparisons with analytical solutions from Khvorostyanov and Curry (2007) on the critical droplet radii and supersaturations of CCN with insoluble fractions

2009 ◽  
Vol 9 (2) ◽  
pp. 9537-9550
Author(s):  
V. I. Khvorostyanov ◽  
J. A. Curry
Keyword(s):  
Analytical Solutions ◽  
Cloud Condensation Nuclei ◽  
Dilute Solution ◽  
Condensation Nuclei ◽  
Critical Droplet ◽  
Critical Supersaturation ◽  
Diluted Solution ◽  
Major Discrepancy ◽  
The Difference ◽  
Similar Solutions

Abstract. Analytical solutions for the critical radii rcr and supersaturations scr of the cloud condensation nuclei with insoluble fractions were derived by Khvorostyanov and Curry (2007, hereafter KC07). Similar solutions were found later by Kokkola et al. (2008, hereafter Kok08); however, Kok08 used the approximation of an ideal dilute solution, while KC07 used more accurate assumptions that account for nonideality of solutions. Kok08 found a large discrepancy with KC07 in the critical supersaturations. Various possible reasons of this are analyzed. It is shown that the major discrepancy was caused by a simple mistake in Kok08 in the equation for the critical supersaturation: erroneous ''plus'' sign between the Kelvin and Raoult terms instead of correct ''minus'' sign. If this mistake is corrected, the equations from Kok08 mostly repeat the equations from KC07, except that Kok08 use the dilute solution approximation. If the mistake in Kok08 is corrected, then the differences in the critical radii and supersaturations do not exceed 16–18%, which characterizes the possible errors of an ideal diluted solution approximation. If the Kok08 scheme is corrected and applied to a nonideal solution, then the difference with KC07 does not exceed 0.4–1%.

scholarly journals The Cloud Condensation Nuclei (CCN) properties of 2-methyltetrols and C3-C6 polyols from osmolality and surface tension measurements

2009 ◽  
Vol 9 (3) ◽  
pp. 973-980 ◽  
Author(s):  
S. Ekström ◽  
B. Nozière ◽  
H.-C. Hansson
Keyword(s):  
Surface Tension ◽  
Organic Acids ◽  
Organic Compounds ◽  
Organic Material ◽  
Cloud Condensation Nuclei ◽  
Global Scale ◽  
Significant Fraction ◽  
Cloud Formation ◽  
Condensation Nuclei ◽  
High Solubility

Abstract. A significant fraction of the organic material in aerosols is made of highly soluble compounds such as sugars (mono- and polysaccharides) and polyols such as the 2-methyltetrols, methylerythritol and methyltreitol. Because of their high solubility these compounds are considered as potentially efficient CCN material. For the 2-methyltetrols, this would have important implications for cloud formation at global scale because they are thought to be produced by the atmospheric oxidation of isoprene. To investigate this question, the complete Köhler curves for C3-C6 polyols and the 2-methyltetrols have been determined experimentally from osmolality and surface tension measurements. Contrary to what was expected, none of these compounds displayed a higher CCN efficiency than organic acids. Their Raoult terms show that this limited CCN efficiency is due to their absence of dissociation in water, this in spite of slight surface-tension effects for the 2-methyltetrols. Thus, compounds such as saccharides and polyols would not contribute more to cloud formation than other organic compounds studied so far. In particular, the presence of 2-methyltetrols in aerosols would not particularly enhance cloud formation in the atmosphere, in contrary to recently suggested.

Effect of organic compounds on cloud condensation nuclei (CCN) activity of sea spray aerosol produced by bubble bursting

2011 ◽  
Vol 45 (39) ◽  
pp. 7462-7469 ◽  
Author(s):  
Meagan J.K. Moore ◽  
Hiroshi Furutani ◽  
Gregory C. Roberts ◽  
Ryan C. Moffet ◽  
Mary K. Gilles ◽  
...  
Keyword(s):  
Organic Compounds ◽  
Cloud Condensation Nuclei ◽  
Sea Spray ◽  
Condensation Nuclei ◽  
Bubble Bursting ◽  
Sea Spray Aerosol ◽  
Ccn Activity

scholarly journals Size-resolved cloud condensation nuclei concentration measurements in the Arctic: two case studies from the summer of 2008

2015 ◽  
Vol 15 (23) ◽  
pp. 13803-13817 ◽  
Author(s):  
J. Zábori ◽  
N. Rastak ◽  
Y. J. Yoon ◽  
I. Riipinen ◽  
J. Ström
Keyword(s):  
Cloud Condensation Nuclei ◽  
Measurement Data ◽  
Particle Diameter ◽  
Cloud Formation ◽  
The Arctic ◽  
Research Station ◽  
Condensation Nuclei ◽  
Air Masses ◽  
The Difference ◽  
Measurement Period

Abstract. The Arctic is one of the most vulnerable regions affected by climate change. Extensive measurement data are needed to understand the atmospheric processes governing this vulnerability. Among these, data describing cloud formation potential are of particular interest, since the indirect effect of aerosols on the climate system is still poorly understood. In this paper we present, for the first time, size-resolved cloud condensation nuclei (CCN) data obtained in the Arctic. The measurements were conducted during two periods in the summer of 2008: one in June and one in August, at the Zeppelin research station (78°54´ N, 11°53´ E) in Svalbard. Trajectory analysis indicates that during the measurement period in June 2008, air masses predominantly originated from the Arctic, whereas the measurements from August 2008 were influenced by mid-latitude air masses. CCN supersaturation (SS) spectra obtained on the 27 June, before size-resolved measurements were begun, and spectra from the 21 and 24 August, conducted before and after the measurement period, revealed similarities between the 2 months. From the ratio between CCN concentration and the total particle number concentration (CN) as a function of dry particle diameter (Dp) at a SS of 0.4 %, the activation diameter (D50), corresponding to CCN / CN = 0.50, was estimated. D50 was found to be 60 and 67 nm for the examined periods in June and August 2008, respectively. Corresponding D50 hygroscopicity parameter (κ) values were estimated to be 0.4 and 0.3 for June and August 2008, respectively. These values can be compared to hygroscopicity values estimated from bulk chemical composition, where κ was calculated to be 0.5 for both June and August 2008. While the agreement between the 2 months is reasonable, the difference in κ between the different methods indicates a size dependence in the particle composition, which is likely explained by a higher fraction of inorganics in the bulk aerosol samples.

scholarly journals Correlation between cloud condensation nuclei concentration and aerosol optical thickness in remote and polluted regions

2009 ◽  
Vol 9 (2) ◽  
pp. 543-556 ◽  
Author(s):  
M. O. Andreae
Keyword(s):  
Optical Thickness ◽  
Cloud Condensation Nuclei ◽  
Anthropogenic Pollution ◽  
Aerosol Optical Thickness ◽  
Condensation Nuclei ◽  
Desert Dust ◽  
Order Of Magnitude ◽  
The Mean ◽  
The Difference ◽  
Remote Sensing Techniques

Abstract. A large number of published and unpublished measurements of cloud condensation nuclei (CCN) concentrations and aerosol optical thickness (AOT) measurements have been analyzed. AOT measurements were obtained mostly from the AERONET network, and selected to be collocated as closely as possible to the CCN investigations. In remote marine regions, CCN0.4 (CCN at a supersaturation of 0.4%) are around 110 cm−3 and the mean AOT500 (AOT at 500 nm) is 0.057. Over remote continental areas, CCN are almost twice as abundant, while the mean AOT500 is ca. 0.075. (Sites dominated by desert dust plumes were excluded from this analysis.) Some, or maybe even most of this difference must be because even remote continental sites are in closer proximity to pollution sources than remote marine sites. This suggests that the difference between marine and continental levels must have been smaller before the advent of anthropogenic pollution. Over polluted marine and continental regions, the CCN concentrations are about one order of magnitude higher than over their remote counterparts, while AOT is about five times higher over polluted than over clean regions. The average CCN concentrations from all studies show a remarkable correlation to the corresponding AOT values, which can be expressed as a power law. This can be very useful for the parameterization of CCN concentrations in modeling studies, as it provides an easily measured proxy for this variable, which is difficult to measure directly. It also implies that, at least at large scales, the radiative and microphysical effects of aerosols on cloud physics are correlated and not free to vary fully independently. While the observed strong empirical correlation is remarkable, it must still be noted that there is about a factor-of-four range of CCN concentrations at a given AOT, and that there remains considerable room for improvement in remote sensing techniques for CCN abundance.

scholarly journals Prediction of cloud condensation nuclei activity for organic compounds using functional group contribution methods

2016 ◽  
Vol 9 (1) ◽  
pp. 111-124 ◽  
Author(s):  
M. D. Petters ◽  
S. M. Kreidenweis ◽  
P. J. Ziemann
Keyword(s):  
Organic Compounds ◽  
Field Experiments ◽  
Functional Group ◽  
Cloud Condensation Nuclei ◽  
Organic Aerosol ◽  
Group Contribution ◽  
Condensation Nuclei ◽  
Aerosol Composition ◽  
Group Contribution Methods ◽  
Ccn Activity

Abstract. A wealth of recent laboratory and field experiments demonstrate that organic aerosol composition evolves with time in the atmosphere, leading to changes in the influence of the organic fraction to cloud condensation nuclei (CCN) spectra. There is a need for tools that can realistically represent the evolution of CCN activity to better predict indirect effects of organic aerosol on clouds and climate. This work describes a model to predict the CCN activity of organic compounds from functional group composition. Following previous methods in the literature, we test the ability of semi-empirical group contribution methods in Köhler theory to predict the effective hygroscopicity parameter, kappa. However, in our approach we also account for liquid–liquid phase boundaries to simulate phase-limited activation behavior. Model evaluation against a selected database of published laboratory measurements demonstrates that kappa can be predicted within a factor of 2. Simulation of homologous series is used to identify the relative effectiveness of different functional groups in increasing the CCN activity of weakly functionalized organic compounds. Hydroxyl, carboxyl, aldehyde, hydroperoxide, carbonyl, and ether moieties promote CCN activity while methylene and nitrate moieties inhibit CCN activity. The model can be incorporated into scale-bridging test beds such as the Generator of Explicit Chemistry and Kinetics of Organics in the Atmosphere (GECKO-A) to evaluate the evolution of kappa for a complex mix of organic compounds and to develop suitable parameterizations of CCN evolution for larger-scale models.

scholarly journals Size-resolved cloud condensation nuclei concentration measurements in the Arctic: two case studies from the summer of 2008

2015 ◽  
Vol 15 (4) ◽  
pp. 5079-5128 ◽  
Author(s):  
J. Zábori ◽  
N. Rastak ◽  
Y. J. Yoon ◽  
I. Riipinen ◽  
J. Ström
Keyword(s):  
Cloud Condensation Nuclei ◽  
Measurement Data ◽  
Particle Diameter ◽  
Cloud Formation ◽  
The Arctic ◽  
Research Station ◽  
Condensation Nuclei ◽  
Air Masses ◽  
The Difference ◽  
Measurement Period

Abstract. The Arctic is one of the most vulnerable regions affected by climate change. Extensive measurement data are needed to understand the atmospheric processes governing this vulnerability. Among these, data describing cloud formation potential are of particular interest, since the indirect effect of aerosols on the climate system is still poorly understood. In this paper we present, for the first time, size-resolved cloud condensation nuclei (CCN) data obtained in the Arctic. The measurements were conducted during two periods in the summer of 2008: one in June, and one in August, at the Zeppelin research station (78°54' N, 11°53' E) in Svalbard. Trajectory analysis indicates that during the measurement period in June 2008, air masses predominantly originated from the Arctic, whereas the measurements from August 2008 were characteristic of mid-latitude air masses. CCN supersaturation (SS) spectra obtained on the 27 June, before size-resolved measurements were begun, and spectra from the 21 and 24 August, conducted before and after the measurement period, revealed similarities between the two months. From the ratio between CCN concentration and the total particle number concentration (CN) as a function of dry particle diameter (Dp) at a SS of 0.4%, the activation diameter (D50), corresponding to CCN / CN = 0.50, was estimated. D50 was found to be 60 and 67 nm for the examined periods in June and August 2008, respectively. Corresponding D50 hygroscopicity parameter (κ) values were estimated to be 0.4 and 0.3 for June and August 2008, respectively. These values can be compared to hygroscopicity values estimated from bulk chemical composition, where κ was calculated to be 0.5 for both June and August 2008. While the agreement between the two months is reasonable, the difference in κ between the different methods indicates a size-dependence in the particle composition, which is likely explained by a higher fraction of sea salt in the bulk aerosol samples.

scholarly journals Prediction of cloud condensation nuclei activity for organic compounds using functional group contribution methods

2015 ◽  
Vol 8 (9) ◽  
pp. 7445-7475 ◽  
Author(s):  
M. D. Petters ◽  
S. M. Kreidenweis ◽  
P. J. Ziemann
Keyword(s):  
Organic Compounds ◽  
Field Experiments ◽  
Functional Group ◽  
Cloud Condensation Nuclei ◽  
Organic Aerosol ◽  
Group Contribution ◽  
Condensation Nuclei ◽  
Aerosol Composition ◽  
Group Contribution Methods ◽  
Ccn Activity

Abstract. A wealth of recent laboratory and field experiments demonstrate that organic aerosol composition evolves with time in the atmosphere, leading to changes in the influence of the organic fraction to cloud condensation nuclei (CCN) spectra. There is a need for tools that can realistically represent the evolution of CCN activity to better predict indirect effects of organic aerosol on clouds and climate. This work describes a model to predict the CCN activity of organic compounds from functional group composition. The model combines Köhler theory with semi-empirical group contribution methods to estimate molar volumes, activity coefficients and liquid-liquid phase boundaries to predict the effective hygroscopicity parameter, kappa. Model evaluation against a selected database of published laboratory measurements demonstrates that kappa can be predicted within a factor of two. Simulation of homologous series is used to identify the relative effectiveness of different functional groups in increasing the CCN activity of weakly functionalized organic compounds. Hydroxyl, carboxyl, aldehyde, hydroperoxide, carbonyl, and ether moieties promote CCN activity while methylene and nitrate moieties inhibit CCN activity. The model can be incorporated into scale-bridging testbeds such as the Generator of Explicit Chemistry and Kinetics of Organics in the Atmosphere to evaluate the evolution of kappa for a complex mix of organic compounds and to develop suitable parameterizations of CCN evolution for larger scale models.

Sign in / Sign up

Export Citation Format

Share Document