The effectiveness of coagulation sink of 3–10 nm atmospheric particles

Cai, Runlong; Häkkinen, Ella; Yan, Chao; Jiang, Jingkun; Kulmala, Markku; Kangasluoma, Juha

doi:10.5194/acp-2022-262

Cited by 2 publications

(1 citation statement)

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“…This occurs due to enhanced coagulational growth as low CoagS leads to high particle number concentrations and promotes particle coagulation. Compared to SA, DMA and OOMs, the CoagS has a lower measurement uncertainty of 10% (Cai et al, 2021b); however, in the calculation of the CoagS, including collision enhancement effect by long range interactions (e.g., van der Waals forces) can increase the CoagS 305 by 30-40% percent (Chan and Mozurkewich, 2001;Cai et al, 2022a). In this work we have used the Fuchs equation to calculate CoagS (Kulmala et al, 2001), which is in line with most of the previous works but does not consider the effect of collision enhancement.…”

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Comprehensive simulations of new particle formation events in Beijing with a cluster dynamics-multicomponent sectional model

et al. 2023

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Abstract. New particle formation (NPF) and growth is a major source of atmospheric fine particles. In polluted urban environments, NPF events are frequently observed with characteristics distinct from those in clean environments. Here we simulate NPF events in urban Beijing with a discrete-sectional model that couples cluster dynamics and multicomponent particle growth. In the model, new particles are formed by sulfuric acid-dimethylamine nucleation, while particle growth is driven by particle coagulation and the condensation of sulfuric acid, its clusters, and oxygenated organic molecules (OOMs). A variable simulation domain in the particle size space is applied to isolate newly formed particles from preexisting ones, which allows us to focus on new particle formation and growth rather than the evolution of particles of non-NPF origin. The simulation yields a rich set of information including the time dependent NPF rates, the cluster concentrations, the particle size distributions, and the time- and size-specific particle chemical compositions. These can be compared with the field observations to comprehensively assess the simulation-observation agreement. Sensitivity analysis with the model further quantifies how metrics of NPF events (e.g., particle survival probability) respond to model input variations and serves as a diagnostic tool to pinpoint the key parameter that leads to simulation-observation discrepancies. Seven typical NPF events in urban Beijing were analyzed. We found that with the observed gaseous precursor concentrations and coagulation sink as model inputs, the simulations roughly captured the evolution of the observed particle size distributions; however, the simulated particle growth rate was insufficient to yield the observed particle number concentrations, survival probability, and mode diameter. With the aid of sensitivity analysis, we identified underdetected OOMs as a likely cause for the discrepancy, and the agreement between the simulation and the observation was improved after we modulated particle growth rates in the simulation by adjusting the abundance of OOMs.

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confidence: 99%

Comprehensive simulations of new particle formation events in Beijing with a cluster dynamics-multicomponent sectional model

et al. 2023

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The effectiveness of the coagulation sink of 3–10 nm atmospheric particles

et al. 2022

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Abstract. As a major source of ultrafine particles, new particle formation (NPF) occurs frequently in various environments. However, the survival of new particles and the frequent occurrence of NPF events in polluted environments have long been perplexing, since new particles are expected to be scavenged by high coagulation sinks. Towards solving these problems, we establish an experimental method and directly measure the effectiveness of the size-dependent coagulation sink of monodisperse 3–10 nm particles in well-controlled chamber experiments. Based on the chamber experiments and long-term atmospheric measurements from Beijing, we then discuss the survival of new particles in polluted environments. In the chamber experiments, the measured coagulation sink of 3–10 nm particles increases significantly with a decreasing particle size, whereas it is not sensitive to the compositions of test particles. Comparison between the measured coagulation coefficient with theoretical predictions shows that almost every coagulation leads to the scavenging of one particle, and the coagulation sink exceeds the hard-sphere kinetic limit due to van der Waals attractive force. For urban Beijing, the effectiveness of the coagulation sink and a moderate or high (e.g., > 3 nm h−1) growth rate of new particles can explain the occurrence of measured NPF events; the moderate growth rate further implies that, in addition to gaseous sulfuric acid, other gaseous precursors also contribute to the growth of new particles.

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The effectiveness of coagulation sink of 3–10 nm atmospheric particles

Cited by 2 publications

References 50 publications

Comprehensive simulations of new particle formation events in Beijing with a cluster dynamics-multicomponent sectional model

Comprehensive simulations of new particle formation events in Beijing with a cluster dynamics-multicomponent sectional model

The effectiveness of the coagulation sink of 3–10 nm atmospheric particles

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