Cloud condensation nuclei droplet growth kinetics of ultrafine particles during anthropogenic nucleation events

Abstract. Measurements of cloud condensation nuclei (CCN) concentrations (cm−3) between 0.2 and 1.0% supersaturation, aerosol size distribution and chemical composition were performed at a remote marine site in the eastern Mediterranean, from September to October 2007 during the FAME07 campaign. Most of the particles activate at ~0.6% supersaturation, characteristic of the aged nature of the aerosol sampled. Application of Köhler theory, using measurements of bulk composition, size distribution, and assuming that organics are insoluble resulted in agreement between predicted and measured CCN concentrations within 7±11% for all supersaturations, with a tendency for CCN underprediction (16±6%; r2=0.88) at the lowest supersaturations (0.21%). Including the effects of the water-soluble organic fraction (which represent around 70% of the total organic content) reduces the average underprediction bias at the low supersaturations, resulting in a total closure error of 0.6±6%. Using threshold droplet growth analysis, the growth kinetics of ambient CCN is consistent with NaCl calibration experiments; hence the presence of aged organics does not suppress the rate of water uptake in this environment. The knowledge of the soluble salt fraction is sufficient for the description of the CCN activity in this area.

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Measurements of cloud condensation nuclei activity and droplet activation kinetics of fresh unprocessed regional dust samples and minerals

Atmospheric Chemistry and Physics ◽

10.5194/acp-11-3527-2011 ◽

2011 ◽

Vol 11 (7) ◽

pp. 3527-3541 ◽

Cited By ~ 88

Author(s):

P. Kumar ◽

I. N. Sokolik ◽

A. Nenes

Keyword(s):

Ammonium Sulfate ◽

Mineral Dust ◽

Cloud Condensation Nuclei ◽

Dust Particles ◽

Droplet Growth ◽

Condensation Nuclei ◽

Activation Kinetics ◽

Droplet Activation ◽

Kinetics Of ◽

Ccn Activity

Abstract. This study reports laboratory measurements of cloud condensation nuclei (CCN) activity and droplet activation kinetics of aerosols dry generated from clays, calcite, quartz, and desert soil samples from Northern Africa, East Asia/China, and Northern America. Based on the observed dependence of critical supersaturation, sc, with particle dry diameter, Ddry, we found that FHH (Frenkel, Halsey and Hill) adsorption activation theory is a far more suitable framework for describing fresh dust CCN activity than Köhler theory. One set of FHH parameters (AFHH ∼ 2.25 ± 0.75, BFHH ∼ 1.20 ± 0.10) can adequately reproduce the measured CCN activity for all species considered, and also explains the large range of hygroscopicities reported in the literature. Based on a threshold droplet growth analysis, mineral dust aerosols were found to display retarded activation kinetics compared to ammonium sulfate. Comprehensive simulations of mineral dust activation and growth in the CCN instrument suggest that this retardation is equivalent to a reduction of the water vapor uptake coefficient (relative to that for calibration ammonium sulfate aerosol) by 30–80%. These results suggest that dust particles do not require deliquescent material to act as CCN in the atmosphere.

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Measurements of cloud condensation nuclei activity and droplet activation kinetics of fresh unprocessed regional dust samples and minerals

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-10-31039-2010 ◽

2010 ◽

Vol 10 (12) ◽

pp. 31039-31081 ◽

Cited By ~ 5

Author(s):

P. Kumar ◽

I. N. Sokolik ◽

A. Nenes

Keyword(s):

Ammonium Sulfate ◽

Mineral Dust ◽

Cloud Condensation Nuclei ◽

Dust Particles ◽

Droplet Growth ◽

Condensation Nuclei ◽

Activation Kinetics ◽

Droplet Activation ◽

Kinetics Of ◽

Ccn Activity

Abstract. This study reports laboratory measurements of cloud condensation nuclei (CCN) activity and droplet activation kinetics of aerosols dry-generated from clays, calcite, quartz, and desert soil samples from Northern Africa, East Asia/China, and Northern America. Based on the observed dependence of critical supersaturation, sc, with particle dry diameter, Ddry, we find that FHH adsorption activation theory is a far more suitable framework for describing fresh dust CCN activity than Köhler theory. One set of FHH parameters (AFFH ~ 2.25 ± 0.75, BFFH ~ 1.20 ± 0.10) can adequately reproduce the measured CCN activity for all species considered, and also explains the large range of hygroscopicities reported in the literature. Based on threshold droplet growth analysis, mineral dust aerosols were found to display retarded activation kinetics compared to ammonium sulfate. Comprehensive simulations of mineral dust activation and growth in the CCN instrument suggest that this retardation is equivalent to a reduction of the water vapor uptake coefficient (relative to that for calibration ammonium sulfate aerosol) by 30–80%. These results suggest that dust particles do not require deliquescent material to act as CCN in the atmosphere.

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Cloud condensation nuclei activity and droplet activation kinetics of wet processed regional dust samples and minerals

Atmospheric Chemistry and Physics ◽

10.5194/acp-11-8661-2011 ◽

2011 ◽

Vol 11 (16) ◽

pp. 8661-8676 ◽

Cited By ~ 49

Author(s):

P. Kumar ◽

I. N. Sokolik ◽

A. Nenes

Keyword(s):

Cloud Condensation Nuclei ◽

Aqueous Suspension ◽

Droplet Growth ◽

Generation Process ◽

Size Distributions ◽

Condensation Nuclei ◽

Activation Kinetics ◽

Droplet Activation ◽

Kinetics Of ◽

Ccn Activity

Abstract. This study reports laboratory measurements of particle size distributions, cloud condensation nuclei (CCN) activity, and droplet activation kinetics of wet generated aerosols from clays, calcite, quartz, and desert soil samples from Northern Africa, East Asia/China, and Northern America. The dependence of critical supersaturation, sc, on particle dry diameter, Ddry, is used to characterize particle-water interactions and assess the ability of Frenkel-Halsey-Hill adsorption activation theory (FHH-AT) and Köhler theory (KT) to describe the CCN activity of the considered samples. Wet generated regional dust samples produce unimodal size distributions with particle sizes as small as 40 nm, CCN activation consistent with KT, and exhibit hygroscopicity similar to inorganic salts. Wet generated clays and minerals produce a bimodal size distribution; the CCN activity of the smaller mode is consistent with KT, while the larger mode is less hydrophilic, follows activation by FHH-AT, and displays almost identical CCN activity to dry generated dust. Ion Chromatography (IC) analysis performed on regional dust samples indicates a soluble fraction that cannot explain the CCN activity of dry or wet generated dust. A mass balance and hygroscopicity closure suggests that the small amount of ions (from low solubility compounds like calcite) present in the dry dust dissolve in the aqueous suspension during the wet generation process and give rise to the observed small hygroscopic mode. Overall these results identify an artifact that may question the atmospheric relevance of dust CCN activity studies using the wet generation method. Based on the method of threshold droplet growth analysis, wet generated mineral aerosols display similar activation kinetics compared to ammonium sulfate calibration aerosol. Finally, a unified CCN activity framework that accounts for concurrent effects of solute and adsorption is developed to describe the CCN activity of aged or hygroscopic dusts.

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Measurements of cloud condensation nuclei activity and droplet activation kinetics of wet processed regional dust samples and minerals

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-11-12561-2011 ◽

2011 ◽

Vol 11 (4) ◽

pp. 12561-12605 ◽

Cited By ~ 4

Author(s):

P. Kumar ◽

I. N. Sokolik ◽

A. Nenes

Keyword(s):

Cloud Condensation Nuclei ◽

Aqueous Suspension ◽

Droplet Growth ◽

Generation Process ◽

Size Distributions ◽

Condensation Nuclei ◽

Activation Kinetics ◽

Droplet Activation ◽

Kinetics Of ◽

Ccn Activity

Abstract. This study reports laboratory measurements of particle size distributions, cloud condensation nuclei (CCN) activity, and droplet activation kinetics of wet generated aerosols from clays, calcite, quartz, and desert soil samples from Northern Africa, East Asia/China, and Northern America. The dependence of critical supersaturation, sc, on particle dry diameter, Ddry, is used to characterize particle-water interactions and assess the ability of Frenkel-Halsey-Hill adsorption activation theory (FHH-AT) and Köhler theory (KT) to describe the CCN activity of the considered samples. Regional dust samples produce unimodal size distributions with particle sizes as small as 40 nm, CCN activation consistent with KT, and exhibit hygroscopicity similar to inorganic salts. Clays and minerals produce a bimodal size distribution; the CCN activity of the smaller mode is consistent with KT, while the larger mode is less hydrophilic, follows activation by FHH-AT, and displays almost identical CCN activity to dry generated dust. Ion Chromatography (IC) analysis performed on regional dust samples indicates a soluble fraction that cannot explain the CCN activity of dry or wet generated dust. A mass balance and hygroscopicity closure suggests that the small amount of ions (of low solubility compounds like calcite) present in the dry dust dissolve in the aqueous suspension during the wet generation process and give rise to the observed small hygroscopic mode. Overall these results identify an artifact that may question the atmospheric relevance of dust CCN activity studies using the wet generation method. Based on a threshold droplet growth analysis, wet generated mineral aerosols display similar activation kinetics compared to ammonium sulfate calibration aerosol. Finally, a unified CCN activity framework that accounts for concurrent effects of solute and adsorption is developed to describe the CCN activity of aged or hygroscopic dusts.

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Cloud condensation nuclei measurements in the eastern Mediterranean marine boundary layer: CCN closure and droplet growth kinetics

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-9-10303-2009 ◽

2009 ◽

Vol 9 (2) ◽

pp. 10303-10336 ◽

Cited By ~ 5

Author(s):

A. Bougiatioti ◽

C. Fountoukis ◽

N. Kalivitis ◽

S. N. Pandis ◽

A. Nenes ◽

...

Keyword(s):

Size Distribution ◽

Growth Kinetics ◽

Eastern Mediterranean ◽

Cloud Condensation Nuclei ◽

Bulk Composition ◽

Organic Content ◽

Water Soluble ◽

Aerosol Size Distribution ◽

Droplet Growth ◽

Condensation Nuclei

Abstract. Measurements of cloud condensation nuclei (CCN) concentrations (cm−3) between 0.2 and 1.0% supersaturation, aerosol size distribution and chemical composition were performed at a remote marine site in the eastern Mediterranean, from September to October 2007 during the FAME-07 campaign. Virtually all the particles activate at 0.8% supersaturation, consistent with the very aged nature of the aerosol sampled. Application of Köhler theory, using measurements of bulk composition and size distribution, and assuming that organics are insoluble resulted in agreement between predicted and measured CCN concentrations within 3.4±11% for all supersaturations, with a tendency for CCN underprediction (15±8%; r2=0.92) at lower supersaturations (0.2-0.4%). Including the effects of the water-soluble organic fraction (which represents around 70% of the total organic content) reduces the underprediction bias at low supersaturations, but introduces a slight overprediction (around 5±15%) bias at higher supersaturations (0.6–0.8%), likely from size-dependent variations of the sulfate to organic ratio. Using threshold droplet growth analysis, the growth kinetics of ambient CCN is consistent with NaCl calibration experiments; hence the presence of aged organics does not suppress the rate of water uptake in this environment. The knowledge of the soluble fraction is sufficient for the description of the CCN activity in this area.

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Cloud condensation nuclei activity, droplet growth kinetics, and hygroscopicity of biogenic and anthropogenic secondary organic aerosol (SOA)

Atmospheric Chemistry and Physics ◽

10.5194/acp-16-1105-2016 ◽

2016 ◽

Vol 16 (2) ◽

pp. 1105-1121 ◽

Cited By ~ 19

Author(s):

D. F. Zhao ◽

A. Buchholz ◽

B. Kortner ◽

P. Schlag ◽

F. Rubach ◽

...

Keyword(s):

Growth Kinetics ◽

Secondary Organic Aerosol ◽

Cloud Condensation Nuclei ◽

Cloud Droplet ◽

Organic Aerosol ◽

Droplet Growth ◽

Biogenic Voc ◽

Degree Of Oxidation ◽

Kinetics Of ◽

Ccn Activity

Abstract. Interaction of biogenic volatile organic compounds (VOCs) with Anthropogenic VOC (AVOC) affects the physicochemical properties of secondary organic aerosol (SOA). We investigated cloud droplet activation (CCN activity), droplet growth kinetics, and hygroscopicity of mixed anthropogenic and biogenic SOA (ABSOA) compared to pure biogenic SOA (BSOA) and pure anthropogenic SOA (ASOA). Selected monoterpenes and aromatics were used as representative precursors of BSOA and ASOA, respectively.We found that BSOA, ASOA, and ABSOA had similar CCN activity despite the higher oxygen to carbon ratio (O/C) of ASOA compared to BSOA and ABSOA. For individual reaction systems, CCN activity increased with the degree of oxidation. Yet, when considering all different types of SOA together, the hygroscopicity parameter, κCCN, did not correlate with O/C. Droplet growth kinetics of BSOA, ASOA, and ABSOA were comparable to that of (NH4)2SO4, which indicates that there was no delay in the water uptake for these SOA in supersaturated conditions.In contrast to CCN activity, the hygroscopicity parameter from a hygroscopic tandem differential mobility analyzer (HTDMA) measurement, κHTDMA, of ASOA was distinctively higher (0.09–0.10) than that of BSOA (0.03–0.06), which was attributed to the higher degree of oxidation of ASOA. The ASOA components in mixed ABSOA enhanced aerosol hygroscopicity. Changing the ASOA fraction by adding biogenic VOC (BVOC) to ASOA or vice versa (AVOC to BSOA) changed the hygroscopicity of aerosol, in line with the change in the degree of oxidation of aerosol. However, the hygroscopicity of ABSOA cannot be described by a simple linear combination of pure BSOA and ASOA systems. This indicates that additional processes, possibly oligomerization, affected the hygroscopicity.Closure analysis of CCN and HTDMA data showed κHTDMA was lower than κCCN by 30–70 %. Better closure was achieved for ASOA compared to BSOA. This discrepancy can be attributed to several reasons. ASOA seemed to have higher solubility in subsaturated conditions and/or higher surface tension at the activation point than that of BSOA.

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Cloud condensation nuclei activity, droplet growth kinetics and hygroscopicity of biogenic and anthropogenic Secondary Organic Aerosol (SOA)

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-15-19903-2015 ◽

2015 ◽

Vol 15 (14) ◽

pp. 19903-19945 ◽

Cited By ~ 5

Author(s):

D. F. Zhao ◽

A. Buchholz ◽

B. Kortner ◽

P. Schlag ◽

F. Rubach ◽

...

Keyword(s):

Growth Kinetics ◽

Secondary Organic Aerosol ◽

Cloud Condensation Nuclei ◽

Cloud Droplet ◽

Organic Aerosol ◽

Droplet Growth ◽

Degree Of Oxidation ◽

Kinetics Of ◽

Aerosol Hygroscopicity ◽

Ccn Activity

Abstract. Interaction of biogenic volatile organic compounds (VOC) with anthropogenic VOC affects the physicochemical properties of secondary organic aerosol (SOA). We investigated cloud droplet activation (CCN activity), droplet growth kinetics, and hygroscopicity of mixed anthropogenic and biogenic SOA (ABSOA) compared to pure biogenic SOA (BSOA) and pure anthropogenic SOA (ASOA). Selected monoterpenes and aromatics were used as representative precursors of BSOA and ASOA, respectively. We found that BSOA, ASOA, and ABSOA had similar CCN activity despite the higher oxygen to carbon ratio (O/C) of ASOA compared to BSOA and ABSOA. For individual reaction systems, CCN activity increased with the degree of oxidation. Yet, when considering all different types of SOA together, the hygroscopicity parameter, κCCN, did not correlate with O/C. Droplet growth kinetics of BSOA, ASOA, and ABSOA was comparable to that of (NH4)2SO4, which indicates that there was no delay in the water uptake for these SOA in supersaturated conditions. In contrast to CCN activity, the hygroscopicity parameter from hygroscopic tandem differential mobility analyzer (HTDMA) measurement, κHTDMA, of ASOA was distinctively higher (0.09–0.10) than that of BSOA (0.03–0.06), which was attributed to the higher degree of oxidation of ASOA. The ASOA components in mixed ABSOA enhanced aerosol hygroscopicity. Changing the ASOA fraction by adding BVOC to ASOA or vice versa AVOC to BSOA changed the hygroscopicity of aerosol, in line with the change in the degree of oxidation of aerosol. However, the hygroscopicity of ABSOA cannot be described by a simple linear combination of pure BSOA and ASOA systems. This indicates that additional processes, possibly oligomerization, affected the hygroscopicity. Closure analysis of CCN and HTDMA data showed κHTDMA was lower than κCCN by 30–70 %. Better closure was achieved for ASOA compared to BSOA. This discrepancy can be attributed to several reasons. ASOA seemed to have higher solubility in subsaturated conditions and/or higher surface tension at the activation point than that of BSOA.

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