scholarly journals Variations of cloud condensation nuclei (CCN) and aerosol activity during fog–haze episode: a case study from Shanghai

2014 ◽  
Vol 14 (22) ◽  
pp. 12499-12512 ◽  
Author(s):  
C. Leng ◽  
Q. Zhang ◽  
D. Zhang ◽  
C. Xu ◽  
T. Cheng ◽  
...  
Keyword(s):  
Cloud Condensation Nuclei ◽  
Great Influence ◽  
Urban Site ◽  
Chemical Compositions ◽  
Condensation Nuclei ◽  
Anthropogenic Pollutants ◽  
Clear Case ◽  
Haze Episode ◽  
Aerosol Fraction ◽  
Clear Cases

Abstract. Measurements of cloud condensation nuclei (CCN), condensation nuclei (CN) and aerosol chemical composition were performed simultaneously at an urban site in Shanghai from 6 to 9 November 2010. The variations of CCN number concentration (NCCN) and aerosol activity (activated aerosol fraction, NCCN/NCN) were examined during a fog–haze co-occurring event. Anthropogenic pollutants emitted from vehicles and unfavorable meteorological conditions such as low planetary boundary layer (PBL) height exerted a great influence on PM2.5 and black carbon (BC) loadings. NCCN at 0.2% supersaturation (SS) mostly fell in the range of 994 to 6268 cm−3, and the corresponding NCCN/NCN varied between 0.09 and 0.57. NCCN and NCCN/NCN usually were usually higher in the hazy case due to increased aerosol concentration in the accumulation mode (100–500 nm), and lower in the foggy–hazy and clear cases. The BC mass concentration posed a strong positive effect on NCCN in the foggy–hazy and hazy cases, whereas it poorly correlated with NCCN in the clear case. NCCN/NCN was weakly related with BC in both foggy–hazy and hazy cases. By using a simplified particle hygroscopicity (κ), the calculated critical dry size (CDS) of activated aerosol did not exceed 130 nm at 0.2% SS in spite of diverse aerosol chemical compositions. The predicted NCCN at 0.2% SS was very successful compared with the observed NCCN in clear case (R2=0.96) and foggy–hazy/hazy cases (R2=0.91). In addition, their corresponding ratios of predicted to observed NCCNwere on average 0.95 and 0.92, respectively. More organic matter is possibly responsible for this closure difference between foggy–hazy/hazy and clear cases. These results reveal that the particulate pollutant burden exerts a significant impact on NCCN, especially NCCN/NCN promotes effectively during the polluted periods.

scholarly journals Variations of Cloud Condensation Nuclei (CCN) and aerosol activity during fog-haze episode: a case study from Shanghai

2014 ◽  
Vol 14 (11) ◽  
pp. 16997-17036 ◽  
Author(s):  
C. Leng ◽  
D. Zhang ◽  
Q. Zhang ◽  
C. Xu ◽  
T. Cheng ◽  
...  
Keyword(s):  
Cloud Condensation Nuclei ◽  
Great Influence ◽  
Urban Site ◽  
Chemical Compositions ◽  
Condensation Nuclei ◽  
Anthropogenic Pollutants ◽  
Haze Episode ◽  
Aerosol Fraction ◽  
Positive Effect

Abstract. Measurements of Cloud condensation nuclei (CCN), condensation nuclei (CN) and aerosol chemical composition were performed simultaneously at an urban site of Shanghai from 6 to 9 November 2010. The variations of CCN number concentration (NCCN) and aerosol activity (activated aerosol fraction, NCCN/NCN) were examined during a fog-haze co-occurring event. Anthropogenic pollutants emitted from vehicles and unfavorable meteorological conditions such as low planetary boundary layer (PBL) height exerted a great influence on CN and black carbon (BC) loadings. NCCN at 0.2% supersaturation (SS) mostly fell in the range of 994 to 6268 cm−3, and the corresponding NCCN/NCN varied between 0.09 and 0.57. NCCN and NCCN/NCN usually were higher in hazy days due to increased aerosol concentration in the accumulation mode (100–500 nm), and lower in foggy-hazy and clear days. BC mass concentration posed a strong positive effect on NCCN in foggy-hazy and hazy days, whereas it poorly correlated with NCCN in clear days. NCCN/NCN was weakly related with BC both in foggy-hazy/hazy and clear days. By using a simplified particle hygroscopicity (κ), the calculated critical dry size (CDS) of activated aerosol did not exceed 130 nm at 0.2% SS in spite of diverse aerosol chemical compositions. The predicted NCCN at 0.2% SS was very successful compared with the observed NCCN in clear days (R2=0.96) and foggy-hazy/hazy days (R2=0.91). In addition, their corresponding ratios of predicted to observed NCCN were on average 0.95 and 0.92, respectively. More organic matter is possibly responsible for this closure difference between foggy-hazy/hazy and clear days. These results reveal that the particulate pollutant burden exerts a significant impact on NCCN, especially NCCN/NCN promotes effectively during the polluted periods.

scholarly journals Method to retrieve cloud condensation nuclei number concentrations using lidar measurements

2019 ◽  
Vol 12 (7) ◽  
pp. 3825-3839 ◽  
Author(s):  
Wangshu Tan ◽  
Gang Zhao ◽  
Yingli Yu ◽  
Chengcai Li ◽  
Jian Li ◽  
...  
Keyword(s):  
Cloud Condensation Nuclei ◽  
Number Concentration ◽  
New Method ◽  
Cloud Base ◽  
Chemical Compositions ◽  
Condensation Nuclei ◽  
Aerosol Cloud ◽  
Lidar Measurements ◽  
Kohler Theory ◽  
Aerosol Cloud Interactions

Abstract. Determination of cloud condensation nuclei (CCN) number concentrations at cloud base is important to constrain aerosol–cloud interactions. A new method to retrieve CCN number concentrations using backscatter and extinction profiles from multiwavelength Raman lidars is proposed. The method implements hygroscopic enhancements of backscatter and extinction with relative humidity to derive dry backscatter and extinction and humidogram parameters. Humidogram parameters, Ångström exponents, and lidar extinction-to-backscatter ratios are then linked to the ratio of CCN number concentration to dry backscatter and extinction coefficient (ARξ). This linkage is established based on the datasets simulated by Mie theory and κ-Köhler theory with in-situ-measured particle size distributions and chemical compositions. CCN number concentration can thus be calculated with ARξ and dry backscatter and extinction. An independent theoretical simulated dataset is used to validate this new method and results show that the retrieved CCN number concentrations at supersaturations of 0.07 %, 0.10 %, and 0.20 % are in good agreement with theoretical calculated values. Sensitivity tests indicate that retrieval error in CCN arises mostly from uncertainties in extinction coefficients and RH profiles. The proposed method improves CCN retrieval from lidar measurements and has great potential in deriving scarce long-term CCN data at cloud base, which benefits aerosol–cloud interaction studies.

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

2015 ◽  
Vol 15 (24) ◽  
pp. 14071-14089 ◽  
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 ◽  
Particle Diameter ◽  
Droplet Surface ◽  
Chemical Compositions ◽  
Condensation Nuclei ◽  
Hygroscopic Properties ◽  
Wide Range

Abstract. Organosulfates have been observed as constituents of atmospheric aerosols in a wide range of environments; however their hygroscopic properties remain uncharacterised. Here, limonene-derived organosulfates with a molecular weight of 250 Da (L-OS 250) were synthesised and used for simultaneous measurements with a hygroscopicity tandem differential mobility analyser (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 diameter for all chemical compositions investigated, indicating that κH-TDMA depends on particle diameter and/or surface effects; however, it is not clear if this trend is statistically significant. 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 particle 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.

scholarly journals Method to retrieve cloud condensation nuclei number concentrations using lidar measurements

2019 ◽  
Author(s):  
Wangshu Tan ◽  
Gang Zhao ◽  
Yingli Yu ◽  
Chengcai Li ◽  
Jian Li ◽  
...  
Keyword(s):  
Cloud Condensation Nuclei ◽  
Number Concentration ◽  
New Method ◽  
Cloud Base ◽  
Chemical Compositions ◽  
Condensation Nuclei ◽  
Aerosol Cloud ◽  
Lidar Measurements ◽  
Kohler Theory ◽  
Aerosol Cloud Interactions

Abstract. Determination of cloud condensation nuclei (CCN) number concentrations at cloud base is important to constrain aerosol-cloud interactions. A new method to retrieve CCN number concentrations using backscatter and extinction profiles from multiwavelength Raman lidars is proposed. The method implements hygroscopic enhancements of backscatter/extinction with relative humidity to derive dry backscatter/extinction and humidogram parameters. Humidogram parameters, Ångström exponents, and lidar extinction-to-backscatter ratios are then linked to the ratio of CCN number concentration to dry backscatter/extinction coefficient (ARξ). This linkage is established based on the datasets simulated by Mie theory and κ-Köhler theory with in situ measured particle size distributions and chemical compositions. CCN number concentration can thus be calculated with ARξ and dry backscatter/extinction. An independent theoretical simulated datasets is used to validate this new method and results show that the retrieved CCN number concentrations at supersaturations of 0.07 %, 0.10 %, and 0.20 % are in good agreement with theoretical calculated values. Sensitivity tests indicate that retrieval error in CCN arise mostly from uncertainties in extinction coefficients and RH profiles. The proposed method improves CCN retrieval from lidar measurements and has great potential in deriving scarce long-term CCN data at cloud base which benefits aerosol-cloud interaction studies.

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.

scholarly journals A broad supersaturation scanning (BS2) approach for rapid measurement of aerosol particle hygroscopicity and cloud condensation nuclei activity

2015 ◽  
Vol 8 (9) ◽  
pp. 9713-9730
Author(s):  
H. Su ◽  
Y. Cheng ◽  
N. Ma ◽  
Z. Wang ◽  
X. Wang ◽  
...  
Keyword(s):  
Cloud Condensation Nuclei ◽  
Aerosol Particles ◽  
Fast Response ◽  
Climate Impact ◽  
Time Interval ◽  
Chemical Compositions ◽  
Condensation Nuclei ◽  
Technical Simplicity ◽  
And Performance ◽  
Aerosol Cloud Interactions

Abstract. The activation and hygroscopicity of cloud condensation nuclei (CCN) are key to understand aerosol–cloud interactions and their climate impact. It can be measured by scanning the particle size and supersaturation in CCN measurements. The scanning of supersaturation is often time-consuming and limits the temporal resolution and performance of CCN measurements. Here we present a new approach, termed broad supersaturation scanning (BS2) method, in which a range of supersaturation is simultaneously scanned reducing the time interval between different supersaturation scans. The practical applicability of the BS2 approach is demonstrated with nano-CCN measurements of laboratory-generated aerosol particles. Model simulations show that the BS2 approach is also applicable for measuring CCN activation of ambient mixed particles. Due to its fast response and technical simplicity, the BS2 approach may be well suited for long-term measurements. Since hygroscopicity is closely related to the fraction of organics/inorganics in aerosol particles, a BS2-CCN counter can also serve as a complementary sensor for fast detection/estimation of aerosol chemical compositions.

scholarly journals Cloud condensation nuclei activity at Jeju Island, Korea in spring 2005

2008 ◽  
Vol 8 (11) ◽  
pp. 2933-2948 ◽  
Author(s):  
M. Kuwata ◽  
Y. Kondo ◽  
Y. Miyazaki ◽  
Y. Komazaki ◽  
J. H. Kim ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Temporal Variation ◽  
Cloud Condensation Nuclei ◽  
Particle Diameter ◽  
Inorganic Ions ◽  
Water Soluble ◽  
Jeju Island ◽  
Chemical Compositions ◽  
Condensation Nuclei ◽  
Soluble Components

Abstract. We measured the number concentrations of cloud condensation nuclei (CCN) and the size distributions of CCN/CN (CN: condensation nuclei) ratios at supersaturations (SSs) of 0.097, 0.27, 0.58, and 0.97% at Jeju Island, Korea during March-April 2005. We made simultaneous measurements of aerosol inorganic ions, water-soluble organic carbon (WSOC), organic carbon (OC), and elemental carbon (EC) in PM2.5. The CCN/CN ratios increased with increasing particle diameter, and the diameter at CCN/CN=0.5 was defined as D50. D50 represents the activation dry diameter of atmospheric particles. The average D50 at SS=0.097% and 0.97% was 136±17 nm and 31±3 nm, respectively. The temporal variation of D50 at SS=0.097% was correlated with the mass fraction of water-soluble components (inorganic ions + WSOC), indicating that the temporal variation of CCN activity was mainly controlled by changes in the water-soluble components fraction. The critical dry diameter (Dcrit), which is the threshold dry diameter for CCN activation, was calculated from the observed aerosol chemical compositions by Köhler theory for comparison with D50. The D50 at SS=0.097% was correlated (r2=0.48) with calculated Dcrit, although Dcrit was larger than D50 by 20–29% on average. The systematic difference between D50 and Dcrit could be caused by the size dependence of the aerosol chemical compositions or surface tension lowering caused by the mixing of water-soluble organic compounds. This difference corresponds to a 27±14% uncertainty in the CCN number concentration estimated from the observed particle number size distribution.

scholarly journals A broad supersaturation scanning (BS2) approach for rapid measurement of aerosol particle hygroscopicity and cloud condensation nuclei activity

2016 ◽  
Vol 9 (10) ◽  
pp. 5183-5192
Author(s):  
Hang Su ◽  
Yafang Cheng ◽  
Nan Ma ◽  
Zhibin Wang ◽  
Xiaoxiang Wang ◽  
...  
Keyword(s):  
Cloud Condensation Nuclei ◽  
Aerosol Particles ◽  
Fast Response ◽  
Time Interval ◽  
Chemical Compositions ◽  
Condensation Nuclei ◽  
Fast Detection ◽  
Technical Simplicity ◽  
And Performance ◽  
Aerosol Cloud Interactions

Abstract. The activation and hygroscopicity of cloud condensation nuclei (CCN) are key to the understanding of aerosol–cloud interactions and their impact on climate. They can be measured by scanning the particle size and supersaturation in CCN measurements. The scanning of supersaturation is often time-consuming and limits the temporal resolution and performance of CCN measurements. Here we present a new approach, termed the broad supersaturation scanning (BS2) method, in which a range of supersaturation is simultaneously scanned, reducing the time interval between different supersaturation scans. The practical applicability of the BS2 approach is demonstrated with nano-CCN measurements of laboratory-generated aerosol particles. Model simulations show that the BS2 approach may also be applicable for measuring CCN activation of ambient mixed particles. Due to its fast response and technical simplicity, the BS2 approach may be well suited for aircraft and long-term measurements. Since hygroscopicity is closely related to the fraction of organics/inorganics in aerosol particles, a BS2-CCN counter can also serve as a complementary sensor for fast detection/estimation of aerosol chemical compositions.

scholarly journals Cloud condensation nuclei activity at Jeju Island, Korea in spring 2005

2007 ◽  
Vol 7 (6) ◽  
pp. 15805-15851 ◽  
Author(s):  
M. Kuwata ◽  
Y. Kondo ◽  
Y. Miyazaki ◽  
Y. Komazaki ◽  
J. H. Kim ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Temporal Variation ◽  
Cloud Condensation Nuclei ◽  
Particle Diameter ◽  
Inorganic Ions ◽  
Water Soluble ◽  
Jeju Island ◽  
Chemical Compositions ◽  
Condensation Nuclei ◽  
Soluble Components

Abstract. We measured the number concentrations of cloud condensation nuclei (CCN) and the size distributions of CCN/CN (CN: condensation nuclei) ratios at supersaturations (SSs) of 0.097, 0.27, 0.58, and 0.97% at Jeju-Island, Korea during March-April 2005. Measurements of aerosol inorganic ions, water-soluble organic carbon (WSOC), organic carbon (OC), and elemental carbon (EC) in PM2.5 were simultaneously made. The CCN/CN ratios increased with increasing particle diameter, and the diameter at CCN/CN=0.5 was defined as D50. D50 represents the activation dry diameter of atmospheric particles. The average D50 at SS=0.097% and 0.97% was 136 nm and 31 nm, respectively. The temporal variation of D50 at SS=0.097% was correlated with the mass fraction of water-soluble components (inorganic ions + WSOC), indicating that the temporal variation of CCN activity was mainly controlled by changes in the water-soluble components fraction. The critical dry diameter (Dcrit), which is the threshold dry diameter for CCN activation, was calculated from the observed aerosol chemical compositions by Köhler theory for comparison with D50. The D50 at SS=0.097% was correlated (r2=0.48) with calculated Dcrit, although Dcrit were larger than D50 by 20–29% on average. The systematic difference between D50 and Dcrit could be caused by the size dependence of the aerosol chemical compositions or surface tension lowering caused by the mixing of water-soluble organic compounds. This difference corresponds to a 27±14% uncertainty in the CCN number concentration estimated from the observed particle number size distribution.

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