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

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

Atmospheric Chemistry and Physics ◽

10.5194/acp-21-2287-2021 ◽

2021 ◽

Vol 21 (3) ◽

pp. 2287-2304

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 ◽

Condensation Growth ◽

The Impact ◽

New Particles

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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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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Atmospheric new particle formation in China

Atmospheric Chemistry and Physics ◽

10.5194/acp-19-115-2019 ◽

2019 ◽

Vol 19 (1) ◽

pp. 115-138 ◽

Cited By ~ 32

Author(s):

Biwu Chu ◽

Veli-Matti Kerminen ◽

Federico Bianchi ◽

Chao Yan ◽

Tuukka Petäjä ◽

...

Keyword(s):

Air Pollution ◽

Growth Rate ◽

Formation Rate ◽

Particle Growth ◽

Particle Formation ◽

New Particle Formation ◽

Growth Mechanisms ◽

Different Types ◽

Different Seasons ◽

Heavy Pollution

Abstract. New particle formation (NPF) studies in China were summarized comprehensively in this paper. NPF frequency, formation rate, and particle growth rate were closely compared among the observations carried out at different types of sites in different regions of China in different seasons, with the aim of exploring the nucleation and particle growth mechanisms. The interactions between air pollution and NPF are discussed, emphasizing the properties of NPF under heavy pollution conditions. The current understanding of NPF cannot fully explain the frequent occurrence of NPF at high aerosol loadings in China, and possible reasons for this phenomenon are proposed. The effects of NPF and some aspects of NPF research requiring further investigation are also summarized in this paper.

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Atmospheric new particle formation in China

10.5194/acp-2018-612 ◽

2018 ◽

Author(s):

Biwu Chu ◽

Veli-Matti Kerminen ◽

Federico Bianchi ◽

Chao Yan ◽

Tuukka Petäjä ◽

...

Keyword(s):

Air Pollution ◽

Growth Rate ◽

Formation Rate ◽

Particle Growth ◽

Particle Formation ◽

New Particle Formation ◽

Growth Mechanisms ◽

Different Types ◽

Different Seasons ◽

Heavy Pollution

Abstract. New particle formation (NPF) studies in China were summarized comprehensively in this paper. NPF frequency, formation rate and particle growth rate were closely compared among the observations carried out at different types of sites in different regions of China in different seasons, with the aim of exploring the nucleation and particle growth mechanisms. The interactions between air pollution and NPF are discussed, emphasizing on the properties of NPF under heavy pollution conditions. The current understanding of NPF cannot not be fully explain the frequent occurrence of NPF at high aerosol loadings in China, and possible reasons for this phenomenon are proposed. The effects of NPF and some aspects of NPF research requiring further investigations are also summarized in this paper.

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Modelling studies of HOMs and their contributions to new particle formation and growth: comparison of boreal forest in Finland and a polluted environment in China

Atmospheric Chemistry and Physics ◽

10.5194/acp-18-11779-2018 ◽

2018 ◽

Vol 18 (16) ◽

pp. 11779-11791 ◽

Cited By ~ 7

Author(s):

Ximeng Qi ◽

Aijun Ding ◽

Pontus Roldin ◽

Zhengning Xu ◽

Putian Zhou ◽

...

Keyword(s):

Sulfuric Acid ◽

Boreal Forest ◽

Environmental Conditions ◽

Eastern China ◽

Particle Growth ◽

Particle Formation ◽

Forest Site ◽

Polluted Environment ◽

New Particle Formation ◽

Multifunctional Compounds

Abstract. Highly oxygenated multifunctional compounds (HOMs) play a key role in new particle formation (NPF), but their quantitative roles in different environments of the globe have not been well studied yet. Frequent NPF events were observed at two “flagship” stations under different environmental conditions, i.e. a remote boreal forest site (SMEAR II) in Finland and a suburban site (SORPES) in polluted eastern China. The averaged formation rate of 6 nm particles and the growth rate of 6–30 nm particles were 0.3 cm−3 s−1 and 4.5 nm h−1 at SMEAR II compared to 2.3 cm−3 s−1 and 8.7 nm h−1 at SORPES, respectively. To explore the differences of NPF at the two stations, the HOM concentrations and NPF events at two sites were simulated with the MALTE-BOX model, and their roles in NPF and particle growth in the two distinctly different environments are discussed. The model provides an acceptable agreement between the simulated and measured concentrations of sulfuric acid and HOMs at SMEAR II. The sulfuric acid and HOM organonitrate concentrations are significantly higher but other HOM monomers and dimers from monoterpene oxidation are lower at SORPES compared to SMEAR II. The model simulates the NPF events at SMEAR II with a good agreement but underestimates the growth of new particles at SORPES, indicating a dominant role of anthropogenic processes in the polluted environment. HOMs from monoterpene oxidation dominate the growth of ultrafine particles at SMEAR II while sulfuric acid and HOMs from aromatics oxidation play a more important role in particle growth. This study highlights the distinct roles of sulfuric acid and HOMs in NPF and particle growth in different environmental conditions and suggests the need for molecular-scale measurements in improving the understanding of NPF mechanisms in polluted areas like eastern China.

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