scholarly journals Chemical composition, microstructure, and hygroscopic properties of aerosol particles at the Zotino Tall Tower Observatory (ZOTTO), Siberia, during a summer campaign

2015 ◽  
Vol 15 (15) ◽  
pp. 8847-8869 ◽  
Author(s):  
E. F. Mikhailov ◽  
G. N. Mironov ◽  
C. Pöhlker ◽  
X. Chi ◽  
M. L. Krüger ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Water Uptake ◽  
Aerosol Particles ◽  
Organic Coating ◽  
Water Soluble ◽  
Submicron Particles ◽  
Hygroscopic Growth ◽  
Accumulation Mode ◽  
Hygroscopic Properties ◽  
Coarse Mode

Abstract. In this study we describe the hygroscopic properties of accumulation- and coarse-mode aerosol particles sampled at the Zotino Tall Tower Observatory (ZOTTO) in central Siberia (61° N, 89° E) from 16 to 21 June 2013. The hygroscopic growth measurements were supplemented with chemical analyses of the samples, including inorganic ions and organic/elemental carbon. In addition, the microstructure and chemical compositions of aerosol particles were analyzed by x-ray micro-spectroscopy (STXM-NEXAFS) and transmission electron microscopy (TEM). A mass closure analysis indicates that organic carbon accounted for 61 and 38 % of particulate matter (PM) in the accumulation mode and coarse mode, respectively. The water-soluble fraction of organic matter was estimated to be 52 and 8 % of PM in these modes. Sulfate, predominantly in the form of ammoniated sulfate, was the dominant inorganic component in both size modes: ~ 34 % in the accumulation mode vs. ~ 47 % in the coarse mode. The hygroscopic growth measurements were conducted with a filter-based differential hygroscopicity analyzer (FDHA) over the range of 5–99.4 % RH in the hydration and dehydration operation modes. The FDHA study indicates that both accumulation and coarse modes exhibit pronounced water uptake approximately at the same relative humidity (RH), starting at ~ 70 %, while efflorescence occurred at different humidities, i.e., at ~ 35 % RH for submicron particles vs. ~ 50 % RH for supermicron particles. This ~ 15 % RH difference was attributed to higher content of organic material in the submicron particles, which suppresses water release in the dehydration experiments. The kappa mass interaction model (KIM) was applied to characterize and parameterize non-ideal solution behavior and concentration-dependent water uptake by atmospheric aerosol samples in the 5–99.4 % RH range. Based on KIM, the volume-based hygroscopicity parameter, κv, was calculated. The κv,ws value related to the water-soluble (ws) fraction was estimated to be ~ 0.15 for the accumulation mode and ~ 0.36 for the coarse mode, respectively. The obtained κv,ws for the accumulation mode is in good agreement with earlier data reported for remote sites in the Amazon rain forest (κv ≈ 0.15) and a Colorado mountain forest (κv ≈ 0.16 ). We used the Zdanovskii–Stokes–Robinson (ZSR) mixing rule to predict the chemical composition dependent hygroscopicity, κv,p. The obtained κv,p values overestimate the experimental FDHA-KIM-derived κv,ws by factors of 1.8 and 1.5 for the accumulation and coarse modes, respectively. This divergence can be explained by incomplete dissolution of the hygroscopic inorganic compounds resulting from kinetic limitations due to a sparingly soluble organic coating. The TEM and STXM-NEXAFS results indicate that aged submicron (> 300 nm) and supermicron aerosol particles possess core–shell structures with an inorganic core, and are enriched in organic carbon at the mixed particle surface. The direct FDHA kinetic studies provide a bulk diffusion coefficient of water of ~ 10−12 cm2 s−1 indicating a semi-solid state of the organic-rich phase leading to kinetic limitations of water uptake and release during hydration and dehydration cycles. Overall, the present ZOTTO data set, obtained in the growing season, has revealed a strong influence of organic carbon on the hygroscopic properties of the ambient aerosols. The sparingly soluble organic coating controls hygroscopic growth, phase transitions, and microstructural rearrangement processes. The observed kinetic limitations can strongly influence the outcome of experiments performed on multi-second timescales, such as the commonly applied HTDMA (Hygroscopicity Tandem Differential Mobility Analyzer) and CCNC (Cloud Condensation Nuclei Counter) measurements.

scholarly journals Chemical composition, microstructure, and hygroscopic properties of aerosol particles at the Zotino Tall Tower Observatory (ZOTTO), Siberia, during a summer campaign

2015 ◽  
Vol 15 (6) ◽  
pp. 7837-7893
Author(s):  
E. F. Mikhailov ◽  
G. N. Mironov ◽  
C. Pöhlker ◽  
X. Chi ◽  
M. L. Krüger ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Organic Carbon ◽  
Water Uptake ◽  
Aerosol Particles ◽  
Water Soluble ◽  
Submicron Particles ◽  
Hygroscopic Growth ◽  
Accumulation Mode ◽  
Hygroscopic Properties ◽  
Coarse Mode

Abstract. In this study we describe the hygroscopic properties of accumulation- and coarse-mode aerosol particles sampled at the Zotino Tall Tower Observatory (ZOTTO) in Central Siberia (61° N; 89° E) from 16 to 21 June 2013. The hygroscopic growth measurements were supplemented with chemical analyses of the samples, including inorganic ions and organic/elemental carbon. In addition, the microstructure and chemical composition of aerosol particles were analyzed by X-ray micro-spectroscopy (STXM-NEXAFS) and transmission electron microscopy (TEM). A mass closure analysis indicates that organic carbon accounted for 61 and 38% of PM in the accumulation mode and coarse mode, respectively. The water soluble fraction of organic matter was estimated to be 52 and 8% of PM in these modes. Sulfate, predominantly in the form of ammoniated sulfate, was the dominant inorganic component in both size modes: ∼34% in the accumulation vs. ∼47% in the coarse mode. The hygroscopic growth measurements were conducted with a filter-based differential hygroscopicity analyzer (FDHA) over the range of 5–99.4% RH in the hydration and dehydration operation modes. The FDHA study indicates that both accumulation and coarse modes exhibit pronounced water uptake approximately at the same RH, starting at ∼70%, while efflorescence occurred at different humidities, i.e., at ∼35% RH for submicron particles vs. ∼50% RH for supermicron particles. This ∼15% RH difference was attributed to higher content of organic material in the submicron particles, which suppresses water release in the dehydration experiments. The kappa mass interaction model (KIM) was applied to characterize and parameterize non-ideal solution behavior and concentration-dependent water uptake by atmospheric aerosol samples in the 5–99.4% RH range. Based on KIM, the volume-based hygroscopicity parameter, κv, was calculated. The κv, ws value related to the water soluble (ws) fraction was estimated to be ∼0.15 for the accumulation mode and ∼0.36 for the coarse mode, respectively. The obtained κv, ws for the accumulation mode is in good agreement with earlier data reported for remote sites in the Amazon rain forest (κv ≈ 0.15) and a Colorado boreal forest (κv ≈ 0.16). We used the Zdanovskii–Stokes–Robinson (ZSR) mixing rule to predict the chemical composition dependent hygroscopicity, κv, p. The obtained κv, p values overestimate the experimental FDHA-KIM-derived κv, ws by factors of 1.8 and 1.5 for the accumulation and coarse modes, respectively. This divergence can be partly explained by incomplete dissolution of the hygroscopic inorganic compounds resulting from kinetic limitations due to a sparingly soluble organic coating. The TEM and STXM-NEXAFS results indicate that aged submicron (>300 nm) and supermicron aerosol particles possess core-shell structures with an inorganic core, and are enriched in organic carbon at the mixed particle surface. The direct FDHA kinetic studies provide a bulk diffusion coefficient of water of ∼10−12 cm2 s−1 indicating a semi-solid state of the organic-rich phase leading to kinetic limitations of water uptake and release during hydration and dehydration cycles. Overall the present ZOTTO data set, obtained in the growing season, has revealed a strong influence of organic carbon on the hygroscopic properties of the ambient aerosols. The sparingly soluble organic coating controls hygroscopic growth, phase transitions, and microstructural rearrangement processes. The observed kinetic limitations can strongly influence the outcome of experiments performed on multi-second time scales, such as the commonly applied HTDMA (Hygroscopicity Tandem Differential Mobility Analyzer) and CCNC (Cloud Condensation Nuclei Counter) measurements.

scholarly journals Tandem configuration of differential mobility and centrifugal particle mass analysers for investigating aerosol hygroscopic properties

2017 ◽  
Vol 10 (3) ◽  
pp. 1269-1280 ◽  
Author(s):  
Sergey S. Vlasenko ◽  
Hang Su ◽  
Ulrich Pöschl ◽  
Meinrat O. Andreae ◽  
Eugene F. Mikhailov
Keyword(s):  
Water Uptake ◽  
Aerosol Particles ◽  
Interaction Model ◽  
Growth Curves ◽  
Particle Mass ◽  
Submicron Particles ◽  
Hygroscopic Growth ◽  
Differential Mobility ◽  
Hygroscopic Properties ◽  
Modal Mass

Abstract. A tandem arrangement of Differential Mobility Analyser and Humidified Centrifugal Particle Mass Analyser (DMA-HCPMA) was developed to measure the deliquescence and efflorescence thresholds and the water uptake of submicron particles over the relative humidity (RH) range from 10 to 95 %. The hygroscopic growth curves obtained for ammonium sulfate and sodium chloride test aerosols are consistent with thermodynamic model predictions and literature data. The DMA-HCPMA system was applied to measure the hygroscopic properties of urban aerosol particles, and the kappa mass interaction model (KIM) was used to characterize and parameterize the concentration-dependent water uptake observed in the 50–95 % RH range. For DMA-selected 160 nm dry particles (modal mass of 3.5 fg), we obtained a volume-based hygroscopicity parameter, κv ≈  0.2, which is consistent with literature data for freshly emitted urban aerosols.Overall, our results show that the DMA-HCPMA system can be used to measure size-resolved mass growth factors of atmospheric aerosol particles upon hydration and dehydration up to 95 % RH. Direct measurements of particle mass avoid the typical complications associated with the commonly used mobility-diameter-based HTDMA technique (mainly due to poorly defined or unknown morphology and density).

scholarly journals Tandem configuration of differential mobility and centrifugal particle mass analyzers for investigating aerosol hygroscopic properties

2016 ◽  
Author(s):  
Sergey S. Vlasenko ◽  
Hang Su ◽  
Ulrich Pöschl ◽  
Meinrat O. Andreae ◽  
Eugene F. Mikhailov
Keyword(s):  
Water Uptake ◽  
Aerosol Particles ◽  
Interaction Model ◽  
Particle Morphology ◽  
Particle Mass ◽  
Submicron Particles ◽  
Mass Analyzer ◽  
Hygroscopic Growth ◽  
Differential Mobility ◽  
Hygroscopic Properties

Abstract. A tandem arrangement of Differential Mobility Analyzer and Humidified Centrifugal Particle Mass Analyzer (DMA-HCPMA) was developed to measure the deliquescence and efflorescence thresholds and the water uptake of submicron particles over the relative humidity (RH) range from 10 % to 95 %. The hygroscopic growth curves obtained for Ammonium sulfate and sodium chloride test aerosols are consistent with thermodynamic model predictions and literature data. The DMA-HCPMA system was applied to measure the hygroscopic properties of urban aerosol particles, and the kappa mass interaction model (KIM) was used to characterize and parameterize the concentration-dependent water uptake observed in the 50–95 % RH range. For DMA-selected 160 nm dry particles (mass of 3.5 fg), we obtained a volume-based hygroscopicity parameter κv ≈ 0.2, which is consistent with literature data for freshly emitted urban aerosols. Overall, our results show that the DMA-HCPMA system can be used to measure size-resolved mass growth factors of atmospheric aerosol particles upon hydration and dehydration up to 95 % RH. The direct measurements of humidified particle mass allow avoiding complications that occur in the commonly used mobility-diameter-based HTDMA technique due to poorly defined particle morphology and density.

scholarly journals Secondary aerosol formation promotes water uptake by organic-rich wildfire haze particles in Equatorial Asia

2017 ◽  
Author(s):  
Jing Chen ◽  
Sri Hapsari Budisulistiorini ◽  
Takuma Miyakawa ◽  
Yuichi Komazaki ◽  
Mikinori Kuwata
Keyword(s):  
Water Uptake ◽  
Mass Fraction ◽  
Water Soluble ◽  
Submicron Particles ◽  
Chemical Information ◽  
Hygroscopic Growth ◽  
Aerosol Formation ◽  
Secondary Formation ◽  
Soluble Organic Fraction ◽  
Haze Episode

Abstract. Diameter growth factors (GF) of 100 nm haze particles at 85 % relative humidity and chemical characteristics were simultaneously monitored at Singapore in October 2015 during a pervasive wildfire haze episode, which was caused by peatland burning in Indonesia. Non-refractory submicron particles (NR-PM1) were dominated by organics (approximating 77.1 % in total mass), whereas sulfate was the most abundant inorganic constituent (11.7 % on average). A statistical analysis of the organic mass spectra showed that most of organics (36.0 % of NR-PM1 mass) were highly oxygenated. Diurnal variations of GF, number fraction of highly hygroscopic mode particles, mass fraction of sulfate, and mass fraction of oxygenated organics (OOA) synchronized well, peaking during daytime. The mean hygroscopicity parameter (κ) of haze particles was 0.189 ± 0.087, and mean κ values of organics were 0.157 ± 0.108 (κorg, bulk organics) and 0.287 ± 0.193 (κOOA, OOA), demonstrating the important roles of both sulfate and highly oxygenated organics in hygroscopic growth of wildfire haze particles. κorg was also affected by the water-soluble organic fraction to some extent. These results show the importance of secondary formation processes in promoting water uptake properties of wildfire haze particles, including both inorganic and organic species. Further detailed size-resolved as well as molecular level chemical information of organics will be necessary for more profound exploration of water uptake by wildfire haze particles in Equatorial Asia.

scholarly journals Secondary aerosol formation promotes water uptake by organic-rich wildfire haze particles in equatorial Asia

2018 ◽  
Vol 18 (11) ◽  
pp. 7781-7798 ◽  
Author(s):  
Jing Chen ◽  
Sri Hapsari Budisulistiorini ◽  
Takuma Miyakawa ◽  
Yuichi Komazaki ◽  
Mikinori Kuwata
Keyword(s):  
Water Uptake ◽  
Water Soluble ◽  
Submicron Particles ◽  
Chemical Information ◽  
Hygroscopic Growth ◽  
Aerosol Formation ◽  
Mass Fractions ◽  
Soluble Organic Fraction ◽  
Haze Episode ◽  
The Mean

Abstract. The diameter growth factor (GF) of 100 nm haze particles at 85 % relative humidity (RH) and their chemical characteristics were simultaneously monitored at Singapore in October 2015 during a pervasive wildfire haze episode that was caused by peatland burning in Indonesia. Non-refractory submicron particles (NR-PM1) were dominated by organics (OA; approximating 77.1 % in total mass), whereas sulfate was the most abundant inorganic constituent (11.7 % on average). A statistical analysis of the organic mass spectra showed that most organics (36.0 % of NR-PM1 mass) were highly oxygenated. Diurnal variations of GF, number fractions of more hygroscopic mode particles, mass fractions of sulfate, and mass fractions of oxygenated organics (OOA) synchronized well, peaking during the day. The mean hygroscopicity parameter (κ) of the haze particles was 0.189 ± 0.087, and the mean κ values of organics were 0.157 ± 0.108 (κorg, bulk organics) and 0.266 ± 0.184 (κOOA, OOA), demonstrating the important roles of both sulfate and highly oxygenated organics in the hygroscopic growth of organics-dominated wildfire haze particles. κorg correlated with the water-soluble organic fraction insignificantly, but it positively correlated with f44 (fraction of the ion fragment at m∕z 44 in total organics) (R = 0.70), implying the oxygenation degree of organics could be more critical for the water uptake of organic compounds. These results further suggest the importance of sulfate and secondary organic aerosol formation in promoting the hygroscopic growth of wildfire haze particles. Further detailed size-resolved as well as molecular-level chemical information about organics is necessary for the profound exploration of water uptake by wildfire haze particles in equatorial Asia.

scholarly journals Hygroscopic properties of ultrafine aerosol particles in the boreal forest: diurnal variation, solubility and the influence of sulfuric acid

2007 ◽  
Vol 7 (1) ◽  
pp. 211-222 ◽  
Author(s):  
M. Ehn ◽  
T. Petäjä ◽  
H. Aufmhoff ◽  
P. Aalto ◽  
K. Hämeri ◽  
...  
Keyword(s):  
Sulfuric Acid ◽  
Boreal Forest ◽  
Diurnal Variation ◽  
Gas Phase ◽  
Aerosol Particles ◽  
Particle Formation ◽  
Time Of Day ◽  
New Particle Formation ◽  
Hygroscopic Growth ◽  
Hygroscopic Properties

Abstract. The hygroscopic growth of aerosol particles present in a boreal forest was measured at a relative humidity of 88%. Simultaneously the gas phase concentration of sulfuric acid, a very hygroscopic compound, was monitored. The focus was mainly on days with new particle formation by nucleation. The measured hygroscopic growth factors (GF) correlated positively with the gaseous phase sulfuric acid concentrations. The smaller the particles, the stronger the correlation, with r=0.20 for 50 nm and r=0.50 for 10 nm particles. The increase in GF due to condensing sulfuric acid is expected to be larger for particles with initially smaller masses. During new particle formation, the changes in solubility of the new particles were calculated during their growth to Aitken mode sizes. As the modal diameter increased, the solubility of the particles decreased. This indicated that the initial particle growth was due to more hygroscopic compounds, whereas the later growth during the evening and night was mainly caused by less hygroscopic or even hydrophobic compounds. For all the measured sizes, a diurnal variation in GF was observed both during days with and without particle formation. The GF was lowest at around midnight, with a mean value of 1.12–1.24 depending on particle size and if new particle formation occurred during the day, and increased to 1.25–1.34 around noon. This can be tentatively explained by day- and nighttime gas-phase chemistry; different vapors will be present depending on the time of day, and through condensation these compounds will alter the hygroscopic properties of the particles in different ways.

scholarly journals On the implications of aerosol liquid water and phase separation for organic aerosol mass

2017 ◽  
Vol 17 (1) ◽  
pp. 343-369 ◽  
Author(s):  
Havala O. T. Pye ◽  
Benjamin N. Murphy ◽  
Lu Xu ◽  
Nga L. Ng ◽  
Annmarie G. Carlton ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Organic Compounds ◽  
Water Uptake ◽  
Liquid Water ◽  
Transport Model ◽  
Organic Aerosol ◽  
Water Soluble ◽  
Organic Nitrates ◽  
Monitoring Networks ◽  
Chemical Transport Model

Abstract. Organic compounds and liquid water are major aerosol constituents in the southeast United States (SE US). Water associated with inorganic constituents (inorganic water) can contribute to the partitioning medium for organic aerosol when relative humidities or organic matter to organic carbon (OM ∕ OC) ratios are high such that separation relative humidities (SRH) are below the ambient relative humidity (RH). As OM ∕ OC ratios in the SE US are often between 1.8 and 2.2, organic aerosol experiences both mixing with inorganic water and separation from it. Regional chemical transport model simulations including inorganic water (but excluding water uptake by organic compounds) in the partitioning medium for secondary organic aerosol (SOA) when RH  >  SRH led to increased SOA concentrations, particularly at night. Water uptake to the organic phase resulted in even greater SOA concentrations as a result of a positive feedback in which water uptake increased SOA, which further increased aerosol water and organic aerosol. Aerosol properties, such as the OM ∕ OC and hygroscopicity parameter (κorg), were captured well by the model compared with measurements during the Southern Oxidant and Aerosol Study (SOAS) 2013. Organic nitrates from monoterpene oxidation were predicted to be the least water-soluble semivolatile species in the model, but most biogenically derived semivolatile species in the Community Multiscale Air Quality (CMAQ) model were highly water soluble and expected to contribute to water-soluble organic carbon (WSOC). Organic aerosol and SOA precursors were abundant at night, but additional improvements in daytime organic aerosol are needed to close the model–measurement gap. When taking into account deviations from ideality, including both inorganic (when RH  >  SRH) and organic water in the organic partitioning medium reduced the mean bias in SOA for routine monitoring networks and improved model performance compared to observations from SOAS. Property updates from this work will be released in CMAQ v5.2.

scholarly journals Synergistic effect of water-soluble species and relative humidity on morphological changes of aerosol particles in Beijing mega-city during severe pollution episodes

2018 ◽  
Author(s):  
Xiaole Pan ◽  
Baozhu Ge ◽  
Zhe Wang ◽  
Yu Tian ◽  
Hang Liu ◽  
...  
Keyword(s):  
Relative Humidity ◽  
Synergistic Effect ◽  
Mass Fraction ◽  
Mass Concentration ◽  
Morphological Changes ◽  
Aerosol Particles ◽  
Water Soluble ◽  
Coarse Mode ◽  
Heavy Pollution ◽  
Soluble Species

Abstract. Depolarization ratio (δ) of backscattered light from aerosol particle is an applicable parameter for real-time distinguishing spherical and non-spherical particles, which has been widely adopted by ground-based Lidar observation and satellite remote sensing. From November 2016 to February of 2017, it consecutively suffered from numbers of severe air pollution at Beijing with daily averaged mass concentration of PM2.5 (aerodynamic diameter less than 2.5 μm) larger than 150 μg/m3. We preformed concurrent measurements of water-soluble chemical species and depolarization properties of aerosol particles on the basis of a continuous dichotomous Aerosol Chemical Speciation Analyzer (ACSA-14) and a bench-top optical particle counter with a polarization detection module (POPC). We found that δ value of ambient particles generally decrease as mass concentration of PM2.5 increased at unfavorable meteorological condition. Ratio of mass concentration of nitrate (NO3−) to that of sulfate (SO42−) in PM2.5 was 1.5 ± 0.6, indicating of great importance of NOx in the formation of heavy pollution. Mass concentration of NO3− in PM2.5 (fNO3) was generally an order of magnitude higher than that in coarse mode (cNO3) with a mean fNO3 / cNO3 ratio of 14 ± 10. Relatively high allocation (fNO3/cNO3 = 5) of NO3− in coarse mode could be partially attributed to hygroscopic growth/coagulation of nitrate-rich fine mode particles under higher relative humidity condition. As a result, δ values of particles with Dp = 2 μm (δDp = 2) and 5 μm (δDp = 5) decreased evidently as the mass fraction of water-soluble species (NO3− and SO42−) increase in both PM2.5 and PM2.5–10, respectively. In particular, due to synergistic effect of RH, δDp = 5 value could decrease by 50 % as mass fraction of NO3− in PM2.5–10 increased from 8 % to 23 %. It suggested that alteration of non-sphericity of mineral dust particles was evident owing to coating with pollutants and heterogeneous reactions on the surface of the particle during heavy pollution period. This study brings the attention to great variability of morphological changes of aerosol particles along the transport, which have great complex effects in evaluating their climate and health effect.

scholarly journals Size-dependent activation of aerosols into cloud droplets at a subarctic background site during the second Pallas Cloud Experiment (2nd PaCE): method development and data evaluation

2009 ◽  
Vol 9 (14) ◽  
pp. 4841-4854 ◽  
Author(s):  
T. Anttila ◽  
P. Vaattovaara ◽  
M. Komppula ◽  
A.-P. Hyvärinen ◽  
H. Lihavainen ◽  
...  
Keyword(s):  
Growth Factors ◽  
Water Uptake ◽  
Method Development ◽  
Water Soluble ◽  
Hygroscopic Growth ◽  
Mixing State ◽  
Cloud Droplets ◽  
Important Conclusion ◽  
Size Dependent ◽  
Background Site

Abstract. In situ measurements of aerosol water uptake and activation of aerosols into cloud droplets provide information on how aerosols influence the microphysical properties of clouds. Here we present a computational scheme that can be used in connection with such measurements to assess the influence of the particle hygroscopicity and mixing state (in terms of the water uptake) on the cloud nucleating ability of particles. Additionally, it provides an estimate for the peak supersaturation of water vapour reached during the formation of the observed cloud(s). The method was applied in interpreting results of a measurement campaign that focused on aerosol-cloud interactions taking place at a subarctic background site located in Northern Finland (second Pallas Cloud Experiment, 2nd PaCE). A set of case studies was conducted, and the observed activation behavior could be successfully explained by a maximum supersaturation that varied between 0.18 and 0.26% depending on the case. In these cases, the diameter corresponding to the activated fraction of 50% was in the range of 110–140 nm, and the particles were only moderately water soluble with hygroscopic growth factors varying between 1.1 and 1.4. The conducted analysis showed that the activated fractions and the total number of particles acting as CCN are expected to be highly sensitive to the particle hygroscopic growth properties. For example, the latter quantity varied over a factor between 1.8 and 3.1, depending on the case, when the mean hygroscopic growth factors were varied by 10%. Another important conclusion is that size-dependent activation profiles carries information on the mixing state of particles.

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