Consistency and applicability of parameterization schemes for the size-resolved aerosol activation ratio based on field measurements in the North China Plain

Abstract. Size-resolved and bulk activation properties of aerosols were measured at a regional/suburban site in the North China Plain (NCP), which is occasionally heavily polluted by anthropogenic aerosol particles and gases. A Cloud Condensation Nuclei (CCN) closure study is conducted with bulk CCN number concentration (NCCN) and calculated CCN number concentration based on the aerosol number size distribution and size-resolved activation properties. The observed CCN number concentration (NCCN-obs) are higher than those observed in other locations than China, with average NCCN-obs of roughly 2000, 3000, 6000, 10 000 and 13 000 cm−3 at supersaturations of 0.056, 0.083, 0.17, 0.35 and 0.70%, respectively. An inferred critical dry diameter (Dm) is calculated based on the NCCN-obs and aerosol number size distribution assuming homogeneous chemical composition. The inferred cut-off diameters are in the ranges of 190–280, 160–260, 95–180, 65–120 and 50–100 nm at supersaturations of 0.056, 0.083, 0.17, 0.35 and 0.7%, with their mean values 230.1, 198.4, 128.4, 86.4 and 69.2 nm, respectively. Size-resolved activation measurements show that most of the 300 nm particles are activated at the investigated supersaturations, while almost no particles of 30 nm are activated even at the highest supersaturation of 0.72%. The activation ratio increases with increasing supersaturation and particle size. The slopes of the activation curves for ambient aerosols are not as steep as those observed in calibrations with ammonium sulfate suggesting that the observed aerosols is an external mixture of more hygroscopic and hydrophobic particles. The calculated CCN number concentrations (NCCN-calc) based on the size-resolved activation ratio and aerosol number size distribution correlate well with the NCCN-obs, and show an average overestimation of 19%. Sensitivity studies of the CCN closure show that the NCCN at each supersaturation is well predicted with the campaign average of size-resolved activation curves. These results indicate that the aerosol number size distribution is critical in the prediction of possible CCN. The CCN number concentration can be reliably estimated using time-averaged, size-resolved activation efficiencies without accounting for the temporal variations.

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NH<sub>3</sub>-promoted hydrolysis of NO<sub>2</sub> induces explosive growth in HONO

10.5194/acp-2018-996 ◽

2018 ◽

Author(s):

Wanyun Xu ◽

Ye Kuang ◽

Chunsheng Zhao ◽

Jiangchuan Tao ◽

Gang Zhao ◽

...

Keyword(s):

North China Plain ◽

North China ◽

Ph Value ◽

Primary Source ◽

Field Measurements ◽

Oh Radicals ◽

The North ◽

The North China Plain ◽

First Time ◽

Hydrolysis Of

Abstract. The study of atmospheric nitrous acid (HONO), which is the primary source of OH radicals, is crucial to atmospheric photochemistry and heterogeneous chemical processes. The heterogeneous NO2 chemistry under haze conditions was pointed out to be one of the missing sources of HONO on the North China Plain, producing sulfate and nitrate in the process. However, controversy exists between various proposed mechanisms, mainly debating on whether SO2 directly takes part in the HONO production process and what roles NH3 and the pH value play in it. In this paper, never before seen explosive HONO production (maximum rate: 16 ppb/hour) was reported and evidence was found for the first time in field measurements during fog episodes (usually with pH > 5) and haze episodes under high relative humidity (usually with pH

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Variation of CCN activity during new particle formation events in the North China Plain

10.5194/acp-2016-23 ◽

2016 ◽

Author(s):

N. Ma ◽

C. S. Zhao ◽

J. C. Tao ◽

Z. J. Wu ◽

S. Kecorius ◽

...

Keyword(s):

North China Plain ◽

North China ◽

Critical Diameter ◽

Particle Formation ◽

New Particle Formation ◽

The North ◽

The North China Plain ◽

Ratio Curve ◽

Activation Ratio ◽

Ccn Activity

Abstract. The aim of this investigation was to obtain a better understanding of the variability of the cloud condensation nuclei (CCN) activity during new particle formation (NPF) events in an anthropogenically polluted atmosphere of the North China Plain (NCP). We investigated the size-resolved activation ratio as well as particle number size distribution, hygroscopicity and chemical composition during an intensive field experiment at a regional atmospheric observatory at Xianghe. Interestingly, two types of NPF events were found, in which the growth of the newly formed particles is dominated by either sulfate or organic matters. The particle CCN activity therefore significantly differs in those NPF events, indicating that it might be difficult to find a simple parameterization of particle CCN activity during NPF events over the NCP. For an accurate estimation of the potential CCN number concentration (NCCN) during NPF events, the variation of CCN activity has to be taken into account. Considering that a fixed activation ratio curve or critical diameter are usually used to calculate NCCN, the influence of the variation of particle CCN activity on the calculation of NCCN during NPF events was evaluated based on these two parameterizations. It was found that NCCN might be underestimated by up to 30 % if a fix activation ratio curve (representative of the region and season) is used in the calculation; and might be underestimated by up to 50 % if a fix critical diameter (representative of the region and season) is used. Therefore, we suggest not using a fixed critical diameter in the prediction of NCCN in NPF seasons. If real-time CCN activity data is not available, using a proper fixed activation ratio curve can be a compromising choice.

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A comparison of the parameterization schemes of fog visibility using the in-situ measurements in the North China Plain

Atmospheric Environment ◽

10.1016/j.atmosenv.2014.03.068 ◽

2014 ◽

Vol 92 ◽

pp. 44-50 ◽

Cited By ~ 2

Author(s):

J. Zhang ◽

H. Xue ◽

Z. Deng ◽

N. Ma ◽

C. Zhao ◽

...

Keyword(s):

North China Plain ◽

North China ◽

In Situ Measurements ◽

Parameterization Schemes ◽

The North ◽

The North China Plain

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Size-resolved and bulk activation properties of aerosols in the North China plain: the importance of aerosol size distribution in the prediction of CCN number concentration

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-11-1333-2011 ◽

2011 ◽

Vol 11 (1) ◽

pp. 1333-1366 ◽

Cited By ~ 6

Author(s):

Z. Z. Deng ◽

C. S. Zhao ◽

N. Ma ◽

P. F. Liu ◽

L. Ran ◽

...

Keyword(s):

Size Distribution ◽

North China Plain ◽

North China ◽

Number Concentration ◽

Aerosol Size Distribution ◽

Number Size Distribution ◽

The North ◽

The North China Plain ◽

Wide Range ◽

Activation Ratio

Abstract. Size-resolved and bulk activation properties of aerosols were measured at a regional/suburban site in the North China Plain (NCP), which is occasionally heavily polluted by anthropogenic aerosol particles and gases. A CCN (Cloud Condensation Nuclei) closure study is conducted with bulk CCN number concentration (NCCN) and calculated NCCN based on the aerosol number size distribution and size-resolved activation properties. The observed NCCN are higher than those observed in other locations than China, with average NCCN of roughly 2000, 3000, 6000, 10 000 and 13 000 cm−3 at supersaturations of 0.056, 0.083, 0.17, 0.35 and 0.70%, respectively. An inferred critical dry diameter (Dm) is calculated based on the measured NCCN and aerosol number size distribution assuming homogeneous chemical composition. This inferred cut off diameter varies in a wide range, indicating that it is impossible to predict NCCN with a fixed critical diameter. Size-resolved activation measurements show that most of the 300 nm particles are activated at the investigated supersaturations, while almost no particles of 30 nm are activated even at the highest supersaturation of 0.72%. The activation ratio increases with increasing supersaturation and particle size. The slopes of the activation curves for ambient aerosols are not as steep as those observed in calibrations with ammonium sulfate suggesting that the observed aerosols is an external mixture of more hygroscopic and hydrophobic particles. This conclusion is confirmed by hygroscopicity measurements performed during two intensive field studies in 2009. The calculated NCCN based on the size-resolved activation ratio and aerosol number size distribution correlate well with the measured NCCN, and show an average overestimation of 19%. Sensitivity studies of the CCN closure show that the NCCN for each supersaturation is well predicted with the campaign average of size-resolved activation curves. These results indicate that the aerosol number size distribution is critical in the prediction of possible CCN. The NCCN can be estimated with average activation curve, along with a well described aerosol number size distribution.

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Variation of CCN activity during new particle formation events in the North China Plain

Atmospheric Chemistry and Physics ◽

10.5194/acp-16-8593-2016 ◽

2016 ◽

Vol 16 (13) ◽

pp. 8593-8607 ◽

Cited By ~ 30

Author(s):

Nan Ma ◽

Chunsheng Zhao ◽

Jiangchuan Tao ◽

Zhijun Wu ◽

Simonas Kecorius ◽

...

Keyword(s):

North China Plain ◽

North China ◽

Critical Diameter ◽

Particle Formation ◽

New Particle Formation ◽

The North ◽

The North China Plain ◽

Ratio Curve ◽

Activation Ratio ◽

Ccn Activity

Abstract. The aim of this investigation was to obtain a better understanding of the variability of the cloud condensation nuclei (CCN) activity during new particle formation (NPF) events in an anthropogenically polluted atmosphere of the North China Plain (NCP). We investigated the size-resolved activation ratio as well as particle number size distribution, hygroscopicity, and volatility during a 4-week intensive field experiment in summertime at a regional atmospheric observatory in Xianghe. Interestingly, based on a case study, two types of NPF events were found, in which the newly formed particles exhibited either a higher or a lower hygroscopicity. Therefore, the CCN activity of newly formed particles in different NPF events was largely different, indicating that a simple parameterization of particle CCN activity during NPF events over the NCP might lead to poor estimates of CCN number concentration (NCCN). For a more accurate estimation of the potential NCCN during NPF events, the variation of CCN activity has to be taken into account. Considering that a fixed activation ratio curve or critical diameter are usually used to calculate NCCN, the influence of the variation of particle CCN activity on the calculation of NCCN during NPF events was evaluated based on the two parameterizations. It was found that NCCN might be underestimated by up to 30 % if a single activation ratio curve (representative of the region and season) were to be used in the calculation; and might be underestimated by up to 50 % if a fixed critical diameter (representative of the region and season) were used. Therefore, we suggest not using a fixed critical diameter in the prediction of NCCN in NPF. If real-time CCN activity data are not available, using a proper fixed activation ratio curve can be an alternative but compromised choice.

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