Impacts of coagulation on the appearance time method for new particle growth rate evaluation and their corrections

Abstract. The growth rate of atmospheric new particles is a key parameter that determines their survival probability of becoming cloud condensation nuclei and hence their impact on the climate. There have been several methods to estimate the new particle growth rate. However, due to the impact of coagulation and measurement uncertainties, it is still challenging to estimate the initial growth rate of new particles, especially in polluted environments with high background aerosol concentrations. In this study, we explore the influences of coagulation on the appearance time method to estimate the growth rate of sub-3 nm particles. The principle of the appearance time method and the impacts of coagulation on the retrieved growth rate are clarified via derivations. New formulae in both discrete and continuous spaces are proposed to correct for the impacts of coagulation. Aerosol dynamic models are used to test the new formulae. New particle formation in urban Beijing is used to illustrate the importance of considering the impacts of coagulation on the sub-3 nm particle growth rate and its calculation. We show that the conventional appearance time method needs to be corrected when the impacts of coagulation sink, coagulation source, and particle coagulation growth are non-negligible compared to the condensation growth. Under the simulation conditions with a constant concentration of non-volatile vapors, the corrected growth rate agrees with the theoretical growth rates. However, the uncorrected parameters, e.g., vapor evaporation and the variation in vapor concentration, may impact the growth rate obtained with the appearance time method. Under the simulation conditions with a varying vapor concentration, the average bias in the corrected 1.5–3 nm particle growth rate ranges from 6 %–44 %, and the maximum bias in the size-dependent growth rate is 150 %. During the test new particle formation event in urban Beijing, the corrected condensation growth rate of sub-3 nm particles was in accordance with the growth rate contributed by sulfuric acid condensation, whereas the conventional appearance time method overestimated the condensation growth rate of 1.5 nm particles by 80 %.

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Impacts of coagulation on the appearance time method for sub-3 nm particle growth rate evaluation and their corrections

10.5194/acp-2020-398 ◽

2020 ◽

Cited By ~ 1

Author(s):

Runlong Cai ◽

Chenxi Li ◽

Xu-Cheng He ◽

Chenjuan Deng ◽

Yiqun Lu ◽

...

Keyword(s):

Growth Rate ◽

Particle Growth ◽

Particle Formation ◽

Vapor Concentration ◽

Initial Growth ◽

New Particle Formation ◽

Appearance Time ◽

High Background ◽

Condensation Growth ◽

The Impact

Abstract. The growth rate of atmospheric new particles is a key parameter that determines their survival probability to become cloud condensation nuclei and hence their impact on the climate. There have been several methods to estimate the new particle growth rate. However, due to the impact of coagulation and measurement uncertainties, it is still challenging to estimate the initial growth rate of sub-3 nm particles, especially in polluted environments with high background aerosol concentrations. In this study, we explore the feasibility of the appearance time method to estimate the growth rate of sub-3 nm particles. The principle of the appearance time method and the impacts of coagulation on the retrieved growth rate are clarified. New formulae in both discrete and continuous spaces are proposed to correct the impacts of coagulation. Aerosol dynamic models are used to test the new formulae. New particle formation in urban Beijing is used to illustrate the importance to consider the impacts of coagulation on sub-3 nm particle growth rate and its calculation. We show that the conventional appearance time method needs to be corrected when the impacts of coagulation sink, coagulation source, and particle coagulation growth are non-negligible compared to the condensation growth. Under the simulation conditions with a constant vapor concentration, the corrected growth rate agrees with the theoretical growth rates. The variation of vapor concentration is found to impact growth rate obtained with the appearance time method. Under the simulation conditions with a varying vapor concentration, the average bias of the corrected 1.5–3 nm particle growth rate range from 6–44 %. During the test new particle formation event in urban Beijing, the corrected condensation growth rate of sub-3 nm particles was in accordance with the growth rate contributed by sulfuric acid condensation, whereas the conventional appearance time method overestimated the condensation growth rate of 1.5 nm particles by 80 %.

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CCN production by new particle formation in the free troposphere

Atmospheric Chemistry and Physics ◽

10.5194/acp-17-1529-2017 ◽

2017 ◽

Vol 17 (2) ◽

pp. 1529-1541 ◽

Cited By ~ 17

Author(s):

Clémence Rose ◽

Karine Sellegri ◽

Isabel Moreno ◽

Fernando Velarde ◽

Michel Ramonet ◽

...

Keyword(s):

Particle Number ◽

Particle Growth ◽

Particle Formation ◽

Number Concentration ◽

Particle Number Concentration ◽

Free Troposphere ◽

New Particle Formation ◽

Data Set ◽

Radiative Processes ◽

The Impact

Abstract. Global models predict that new particle formation (NPF) is, in some environments, responsible for a substantial fraction of the total atmospheric particle number concentration and subsequently contributes significantly to cloud condensation nuclei (CCN) concentrations. NPF events were frequently observed at the highest atmospheric observatory in the world, on Chacaltaya (5240 m a.s.l.), Bolivia. The present study focuses on the impact of NPF on CCN population. Neutral cluster and Air Ion Spectrometer and mobility particle size spectrometer measurements were simultaneously used to follow the growth of particles from cluster sizes down to ∼ 2 nm up to CCN threshold sizes set to 50, 80 and 100 nm. Using measurements performed between 1 January and 31 December 2012, we found that 61 % of the 94 analysed events showed a clear particle growth and significant enhancement of the CCN-relevant particle number concentration. We evaluated the contribution of NPF, relative to the transport and growth of pre-existing particles, to CCN size. The averaged production of 50 nm particles during those events was 5072, and 1481 cm−3 for 100 nm particles, with a larger contribution of NPF compared to transport, especially during the wet season. The data set was further segregated into boundary layer (BL) and free troposphere (FT) conditions at the site. The NPF frequency of occurrence was higher in the BL (48 %) compared to the FT (39 %). Particle condensational growth was more frequently observed for events initiated in the FT, but on average faster for those initiated in the BL, when the amount of condensable species was most probably larger. As a result, the potential to form new CCN was higher for events initiated in the BL (67 % against 53 % in the FT). In contrast, higher CCN number concentration increases were found when the NPF process initially occurred in the FT, under less polluted conditions. This work highlights the competition between particle growth and the removal of freshly nucleated particles by coagulation processes. The results support model predictions which suggest that NPF is an effective source of CCN in some environments, and thus may influence regional climate through cloud-related radiative processes.

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New Particle Formation and impact on CCN concentrations in the boundary layer and free troposphere at the high altitude station of Chacaltaya (5240 m a.s.l.), Bolivia

10.5194/acp-2016-696 ◽

2016 ◽

Author(s):

C. Rose ◽

K. Sellegri ◽

I. Moreno ◽

F. Velarde ◽

M. Ramonet ◽

...

Keyword(s):

Boundary Layer ◽

Particle Number ◽

Particle Growth ◽

Particle Formation ◽

Number Concentration ◽

Particle Number Concentration ◽

Free Troposphere ◽

New Particle Formation ◽

Radiative Processes ◽

The Impact

Abstract. Global models predict that new particle formation (NPF) is, in some environments, responsible for a substantial fraction of the total atmospheric particle number concentration and subsequently contribute significantly to cloud condensation nuclei (CCN) concentrations. NPF events were frequently observed at the highest atmospheric observatory in the world, Chacaltaya (5240 m a.s.l.), Bolivia. The present study focuses on the impact of NPF on CCN population. Neutral cluster and Air Ion Spectrometer and mobility particle size spectrometer measurements were simultaneously used to follow the growth of particles from cluster sizes down to ~ 2 nm up to CCN threshold sizes set to 50, 80 and 100 nm. Using measurements performed between January 1 and December 31 2012, we found that 61% of the 94 analysed events showed a clear particle growth and significant enhancement of the CCN-relevant particle number concentration. We evaluated the contribution of NPF events relative to the transport of pre-existing particles to the site. The averaged production of 50 nm particles during those events was 5072 cm−3, and 1481 cm−3 for 100 nm particles, with a larger contribution of NPF compared to transport, especially during the wet season. The data set was further segregated into boundary layer (BL) and free troposphere (FT) conditions at the site. The NPF frequency of occurrence was higher in the BL (48 %) compared to the FT (39 %). Particle condensational growth was more frequently observed for events initiated in the FT, but on average faster for those initiated in the BL, when the amount of condensable species was most probably larger. As a result, the potential to form new CCN was higher for events initiated in the BL (67 % against 56 % in the FT). In contrast, higher CCN number concentration increases were found when the NPF process initially occurred in the FT, under less polluted conditions. This work highlights the competition between particle growth and the removal of freshly nucleated particles by coagulation processes. The results support model predictions which suggest that NPF is an effective source of CCN in some environments, and thus may influence regional climate through cloud related radiative processes.

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Growth of atmospheric nano-particles by heterogeneous nucleation of organic vapor

Atmospheric Chemistry and Physics ◽

10.5194/acp-13-6523-2013 ◽

2013 ◽

Vol 13 (13) ◽

pp. 6523-6531 ◽

Cited By ~ 14

Author(s):

J. Wang ◽

R. L. McGraw ◽

C. Kuang

Keyword(s):

Atmospheric Aerosols ◽

Heterogeneous Nucleation ◽

Particle Formation ◽

Nano Particles ◽

High Rate ◽

Vapor Concentration ◽

Strong Increase ◽

Initial Growth ◽

New Particle Formation ◽

Cluster Number

Abstract. Atmospheric aerosols play critical roles in air quality, public health, and visibility. In addition, they strongly influence climate by scattering solar radiation and by changing the reflectivity and lifetime of clouds. One major but still poorly understood source of atmospheric aerosols is new particle formation, which consists of the formation of thermodynamically stable clusters from trace gas molecules (homogeneous nucleation) followed by growth of these clusters to a detectable size (~3 nm). Because freshly nucleated clusters are most susceptible to loss due to high rate of coagulation with pre-existing aerosol population, the initial growth rate strongly influences the rate of new particle formation and ambient aerosol population. Whereas many field observations and modeling studies indicate that organics enhance the initial growth of the clusters and therefore new particle formation, thermodynamic considerations would suggest that the strong increase of equilibrium vapor concentration due to cluster surface curvature (Kelvin effect) may prevent ambient organics from condensing on these small clusters. Here, the contribution of organics to the initial cluster growth is described as heterogeneous nucleation of organic molecules onto these clusters. We find that the strong gradient in cluster population with respect to its size leads to positive cluster number flux. This positive flux drives the growth of clusters substantially smaller than the Kelvin diameter, conventionally considered the minimum particle size that can be grown through condensation. The conventional approach neglects the contribution from the cluster concentration gradient, and underestimates the cluster survival probabilities by a factor of up to 60 if early growth of clusters is due to both condensation of sulfuric acid and heterogeneous nucleation of organic vapors.

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Flux induced growth of atmospheric nano-particles by organic vapors

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-12-22813-2012 ◽

2012 ◽

Vol 12 (9) ◽

pp. 22813-22833 ◽

Cited By ~ 2

Author(s):

J. Wang ◽

R. L. McGraw ◽

C. Kuang

Keyword(s):

Atmospheric Aerosols ◽

Particle Formation ◽

Nano Particles ◽

High Rate ◽

Vapor Concentration ◽

Strong Increase ◽

Initial Growth ◽

New Particle Formation ◽

Cluster Number ◽

Condensational Growth

Abstract. Atmospheric aerosols play critical roles in air quality, public health, and visibility. In addition, they strongly influence climate by scattering solar radiation and by changing the reflectivity and lifetime of clouds. One major but still poorly understood source of atmospheric aerosol is new particle formation, which consists of the formation of thermodynamically stable clusters from trace gas molecules (homogeneous nucleation) followed by growth of these clusters to a detectable size (~3 nm). Because freshly nucleated clusters are most susceptible to loss due to high rate of coagulation with pre-existing aerosol population, the initial growth rate strongly influences the rate of new particle formation and ambient aerosol population. Whereas many field observations and modeling studies indicate that organics enhance the initial growth of the clusters and therefore new particle formation, thermodynamic considerations would suggest that the strong increase of equilibrium vapor concentration due to cluster surface curvature (Kelvin effect) may prevent ambient organics from condensing on these small clusters. Here the initial condensational growth of freshly nucleated clusters is described as heterogeneous nucleation of organic molecules onto these clusters. We find that the strong gradient in cluster population with respect to its size lead to positive cluster number flux, and therefore driving the growth of clusters substantially smaller than the Kelvin diameter, conventionally considered as the minimum particle size that can be grown through condensation. The conventional approach neglects this contribution from the cluster concentration gradient, and underestimates the rate of new particle formation by a factor of up to 60.

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Particle hygroscopicity during atmospheric new particle formation events: implications for the chemical species contributing to particle growth

Atmospheric Chemistry and Physics ◽

10.5194/acp-13-6637-2013 ◽

2013 ◽

Vol 13 (13) ◽

pp. 6637-6646 ◽

Cited By ~ 18

Author(s):

Z. Wu ◽

W. Birmili ◽

L. Poulain ◽

Z. Wang ◽

M. Merkel ◽

...

Keyword(s):

Growth Rate ◽

Sulfuric Acid ◽

Chemical Species ◽

Particle Growth ◽

Particle Formation ◽

Water Soluble ◽

Alternative Methods ◽

Normal Distribution Function ◽

Particle Fraction ◽

New Particle Formation

Abstract. This study examines the hygroscopicity of newly formed particles (diameters range 25–45 nm) during two atmospheric new particle formation (NPF) events in the German mid-level mountains during the Hill Cap Cloud Thuringia 2010 (HCCT-2010) field experiment. At the end of the NPF event involving clear particle growth, we measured an unusually high soluble particle fraction of 58.5% at 45 nm particle size. The particle growth rate contributed through sulfuric acid condensation only accounts for around 6.5% of the observed growth rate. Estimations showed that sulfuric acid condensation explained, however, only around 10% of that soluble particle fraction. Therefore, the formation of additional water-soluble matter appears imperative to explain the missing soluble fraction. Although direct evidence is missing, we consider water-soluble organics as candidates for this mechanism. For the case with clear growth process, the particle growth rate was determined by two alternative methods based on tracking the mode diameter of the nucleation mode. The mean particle growth rate obtained from the inter-site data comparison using Lagrangian consideration is 3.8 (± 2.6) nm h−1. During the same period, the growth rate calculated based on one site data is 5.0 nm h−1 using log-normal distribution function method. In light of the fact that considerable uncertainties could be involved in both methods, we consider both estimated growth rates consistent.

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New Particle Formation and Sub-10 nm Size Distribution Measurements during the A-LIFE field experiment in Paphos, Cyprus

10.5194/acp-2019-1123 ◽

2019 ◽

Author(s):

Sophia Brilke ◽

Nikolaus Fölker ◽

Thomas Müller ◽

Konrad Kandler ◽

Xianda Gong ◽

...

Keyword(s):

Growth Rate ◽

Particle Size ◽

Field Experiment ◽

Size Distribution ◽

Particle Formation ◽

Atmospheric Environment ◽

Aerosol Size Distribution ◽

Initial Growth ◽

New Particle Formation ◽

Nucleation Mode

Abstract. Atmospheric particle size distributions were measured in Paphos, Cyprus, during the A-LIFE (Absorbing aerosol layers in a changing climate: aging, lifetime and dynamics) field experiment from April 3–30, 2017. The newly developed DMA-train is deployed for the first time in an atmospheric environment for the direct measurement of the nucleation mode size range between 1.8–10 nm diameter. The DMA-train setup consists of seven size channels, of which five are set to fixed particle mobility diameters and two additional diameters are obtained by alternating voltage settings in one DMA every 10 s. In combination with a conventional Mobility Particle Size Spectrometer (MPSS) and an Aerodynamic Particle Sizer (APS) the complete atmospheric aerosol size distribution from 1.8 nm–10 µm is covered. The focus of the A-LIFE study is to characterize new particle formation (NPF) in the Eastern Mediterranean region at a measurement site with strong local pollution sources. The nearby Paphos airport was found to be a large emission source for nucleation mode particles and we analysed the size distribution of the airport emission plumes at approximately 500 m from the main runway. The analysis yielded 9 NPF events in 27 measurement days from the combined analysis of the DMA-train, MPSS and trace gas monitors. Growth rate calculations were performed and a size-dependency of the initial growth rate (

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Changes in the production rate of secondary aerosol particles in Central Europe in view of decreasing SO<sub>2</sub> emissions between 1996 and 2006

Atmospheric Chemistry and Physics ◽

10.5194/acp-10-1071-2010 ◽

2010 ◽

Vol 10 (3) ◽

pp. 1071-1091 ◽

Cited By ~ 61

Author(s):

A. Hamed ◽

W. Birmili ◽

J. Joutsensaari ◽

S. Mikkonen ◽

A. Asmi ◽

...

Keyword(s):

Growth Rate ◽

Cloud Condensation Nuclei ◽

Formation Rate ◽

Global Radiation ◽

Particle Diameter ◽

Particle Formation ◽

Research Station ◽

Particle Nucleation ◽

New Particle Formation ◽

New Particles

Abstract. In anthropogenically influenced atmospheres, sulphur dioxide (SO2) is the main precursor of gaseous sulphuric acid (H2SO4), which in turn is a main precursor for atmospheric particle nucleation. As a result of socio-economic changes, East Germany has seen a dramatic decrease in anthropogenic SO2 emissions between 1989 and present, as documented by routine air quality measurements in many locations. We have attempted to evaluate the influence of changing SO2 concentrations on the frequency and intensity of new particle formation (NPF) using two different data sets (1996–1997; 2003–2006) of experimental particle number size distributions (diameter range 3–750 nm) from the atmospheric research station Melpitz near Leipzig, Germany. Between the two periods SO2 concentrations decreased by 65% on average, while the frequency of NPF events dropped by 45%. Meanwhile, the average formation rate of 3 nm particles decreased by 68% on average. The trends were statistically significant and therefore suggest a connection between the availability of anthropogenic SO2 and freshly formed new particles. In contrast to the decrease in new particle formation, we found an increase in the mean growth rate of freshly nucleated particles (+22%), suggesting that particle nucleation and subsequent growth into larger sizes are delineated with respect to their precursor species. Using three basic parameters, the condensation sink for H2SO4, the SO2 concentration, and the global radiation intensity, we were able to define the characteristic range of atmospheric conditions under which particle formation events take place at the Melpitz site. While the decrease in the concentrations and formation rates of the new particles was rather evident, no similar decrease was found with respect to the generation of cloud condensation nuclei (CCN; particle diameter >100 nm) as a result of atmospheric nucleation events. On the contrary, the production of CCN following nucleation events appears to have increased by tens of percents. Our aerosol dynamics model simulations suggest that such an increase can be caused by the increased particle growth rate.

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The role of low-volatility organic compounds in initial particle growth in the atmosphere

Nature ◽

10.1038/nature18271 ◽

2016 ◽

Vol 533 (7604) ◽

pp. 527-531 ◽

Cited By ~ 267

Author(s):

Jasmin Tröstl ◽

Wayne K. Chuang ◽

Hamish Gordon ◽

Martin Heinritzi ◽

Chao Yan ◽

...

Keyword(s):

Growth Rate ◽

Sulfuric Acid ◽

Cloud Condensation Nuclei ◽

Particle Growth ◽

Initial Growth ◽

Atmospheric Conditions ◽

Condensation Nuclei ◽

Subsequent Growth ◽

New Particles

Abstract About half of present-day cloud condensation nuclei originate from atmospheric nucleation, frequently appearing as a burst of new particles near midday1. Atmospheric observations show that the growth rate of new particles often accelerates when the diameter of the particles is between one and ten nanometres2,3. In this critical size range, new particles are most likely to be lost by coagulation with pre-existing particles4, thereby failing to form new cloud condensation nuclei that are typically 50 to 100 nanometres across. Sulfuric acid vapour is often involved in nucleation but is too scarce to explain most subsequent growth5,6, leaving organic vapours as the most plausible alternative, at least in the planetary boundary layer7,8,9,10. Although recent studies11,12,13 predict that low-volatility organic vapours contribute during initial growth, direct evidence has been lacking. The accelerating growth may result from increased photolytic production of condensable organic species in the afternoon2, and the presence of a possible Kelvin (curvature) effect, which inhibits organic vapour condensation on the smallest particles (the nano-Köhler theory)2,14, has so far remained ambiguous. Here we present experiments performed in a large chamber under atmospheric conditions that investigate the role of organic vapours in the initial growth of nucleated organic particles in the absence of inorganic acids and bases such as sulfuric acid or ammonia and amines, respectively. Using data from the same set of experiments, it has been shown15 that organic vapours alone can drive nucleation. We focus on the growth of nucleated particles and find that the organic vapours that drive initial growth have extremely low volatilities (saturation concentration less than 10−4.5 micrograms per cubic metre). As the particles increase in size and the Kelvin barrier falls, subsequent growth is primarily due to more abundant organic vapours of slightly higher volatility (saturation concentrations of 10−4.5 to 10−0.5 micrograms per cubic metre). We present a particle growth model that quantitatively reproduces our measurements. Furthermore, we implement a parameterization of the first steps of growth in a global aerosol model and find that concentrations of atmospheric cloud concentration nuclei can change substantially in response, that is, by up to 50 per cent in comparison with previously assumed growth rate parameterizations.

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Atmospheric new particle formation from sulfuric acid and amines in a Chinese megacity

Science ◽

10.1126/science.aao4839 ◽

2018 ◽

Vol 361 (6399) ◽

pp. 278-281 ◽

Cited By ~ 130

Author(s):

Lei Yao ◽

Olga Garmash ◽

Federico Bianchi ◽

Jun Zheng ◽

Chao Yan ◽

...

Keyword(s):

Sulfuric Acid ◽

Secondary Particle ◽

Particle Growth ◽

Particle Formation ◽

New Particle Formation ◽

Ambient Conditions ◽

Organic Species ◽

Kinetics Simulation ◽

Very High ◽

New Particles

Atmospheric new particle formation (NPF) is an important global phenomenon that is nevertheless sensitive to ambient conditions. According to both observation and theoretical arguments, NPF usually requires a relatively high sulfuric acid (H2SO4) concentration to promote the formation of new particles and a low preexisting aerosol loading to minimize the sink of new particles. We investigated NPF in Shanghai and were able to observe both precursor vapors (H2SO4) and initial clusters at a molecular level in a megacity. High NPF rates were observed to coincide with several familiar markers suggestive of H2SO4–dimethylamine (DMA)–water (H2O) nucleation, including sulfuric acid dimers and H2SO4-DMA clusters. In a cluster kinetics simulation, the observed concentration of sulfuric acid was high enough to explain the particle growth to ~3 nanometers under the very high condensation sink, whereas the subsequent higher growth rate beyond this size is believed to result from the added contribution of condensing organic species. These findings will help in understanding urban NPF and its air quality and climate effects, as well as in formulating policies to mitigate secondary particle formation in China.

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