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

Cai, Runlong; Li, Chenxi; He, Xu‐Cheng; Deng, Chao; Lu, Yiqun; Yin, Rujing; Yan, Chao; Wang, Lin; Jiang, Jingkun; Kulmala, Markku; Kangasluoma, Juha

doi:10.5194/acp-2020-398

Cited by 3 publications

(3 citation statements)

References 39 publications

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“…For instance, the observed GR in the sub-3 nm size range is influenced by the estimation method and, thus, has an impact on the ratios of the calculated GR 1−3 over the observed GR 1−3 . As shown in Figure S6b, a recently corrected appearance time method 21 gave higher values of the observed GR 1−3 than the log-normal distribution function method and, thus, lower ratios. Nevertheless, results from both methods support that the condensation of H 2 SO 4 and its clusters contributes significantly to the growth of particles in the sub-3 nm size range.…”

Section: Methodsmentioning

confidence: 87%

“…Also, due to the underestimation of the coagulation effect, new particle formation rates from the Cosmics Leaving OUtdoor Droplets (CLOUD) chamber studies on sulfuric acid-dimethylamine nucleation were later corrected to be a factor of 10 faster than previously published results. 20 In addition, Cai et al 21 showed that neglecting coagulation scavenging can result in overestimation when evaluating the particle growth rate from the measured data.…”

Section: Introductionmentioning

confidence: 99%

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Seasonal Characteristics of New Particle Formation and Growth in Urban Beijing

Deng

Dada

et al. 2020

Environ. Sci. Technol.

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Understanding the atmospheric new particle formation (NPF) process within the global range is important for revealing the budget of atmospheric aerosols and their impacts. We investigated the seasonal characteristics of NPF in the urban environment of Beijing. Aerosol size distributions down to ∼1∼1 nm and H 2 SO 4 concentration were measured during 2018-2019.2018-2019. The observed formation rate of 1.5 nm particles (J 1.5 ) is significantly higher than those in the clean environment, e.g., Hyytiala;Hyytiala, whereas the growth rate is relatively lower. Both J 1.5 and NPF frequency in urban Beijing showed a clear seasonal variation with maxima in winter and minima in summer, while the observed growth rates were generally within the same range around the year. We show that ambient temperature is a governing factor driving the seasonal variation of J 1.5 . In contrast, the condensation sink showed no significant seasonal variation during the NPF periods and the daily maximum H 2 SO 4 concentration was slightly higher in summer than that in winter. In all four seasons, condensation of H 2 SO 4 and (H 2 SO 4 ) nn (amine) nn clusters contributes significantly to the growth rates in the sub-3 nm size range, whereas it is less important for the observed growth rates of particles above 3 nm. Therefore, other species are always needed for the growth of larger particles.

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Section: Methodsmentioning

confidence: 87%

Section: Introductionmentioning

confidence: 99%

Seasonal Characteristics of New Particle Formation and Growth in Urban Beijing

Deng

Dada

et al. 2020

Environ. Sci. Technol.

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103

114

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“…The measured data for Fig. 8 are available at https://doi.org/10.5281/zenodo.4506345 (Cai, 2021). The simulation results shown in Figs.…”

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confidence: 99%

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

Cai

et al. 2021

Atmos. Chem. Phys.

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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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