Size-resolved and bulk activation properties of aerosols in the North China Plain
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 co...
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2011-04-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | http://www.atmos-chem-phys.net/11/3835/2011/acp-11-3835-2011.pdf |
| _version_ | 1811317690979057664 |
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| author | Z. Z. Deng C. S. Zhao N. Ma P. F. Liu L. Ran W. Y. Xu J. Chen Z. Liang S. Liang M. Y. Huang X. C. Ma Q. Zhang J. N. Quan P. Yan S. Henning K. Mildenberger E. Sommerhage M. Schäfer F. Stratmann A. Wiedensohler |
| author_facet | Z. Z. Deng C. S. Zhao N. Ma P. F. Liu L. Ran W. Y. Xu J. Chen Z. Liang S. Liang M. Y. Huang X. C. Ma Q. Zhang J. N. Quan P. Yan S. Henning K. Mildenberger E. Sommerhage M. Schäfer F. Stratmann A. Wiedensohler |
| author_sort | Z. Z. Deng |
| collection | DOAJ |
| description | 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 (<i>N</i><sub>CCN</sub>) and calculated CCN number concentration based on the aerosol number size distribution and size-resolved activation properties. <br><br> The observed CCN number concentration (<i>N</i><sub>CCN-obs</sub>) are higher than those observed in other locations than China, with average <i>N</i><sub>CCN-obs</sub> of roughly 2000, 3000, 6000, 10 000 and 13 000 cm<sup>−3</sup> at supersaturations of 0.056, 0.083, 0.17, 0.35 and 0.70%, respectively. An inferred critical dry diameter (<i>D</i><sub>m</sub>) is calculated based on the <i>N</i><sub>CCN-obs</sub> 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. <br><br> 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. <br><br> The calculated CCN number concentrations (<i>N</i><sub>CCN-calc</sub>) based on the size-resolved activation ratio and aerosol number size distribution correlate well with the <i>N</i><sub>CCN-obs</sub>, and show an average overestimation of 19%. Sensitivity studies of the CCN closure show that the <i>N</i><sub>CCN</sub> 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. |
| first_indexed | 2024-04-13T12:12:43Z |
| format | Article |
| id | doaj.art-60d65831e4f34773b9de09a7a9fd5ecd |
| institution | Directory Open Access Journal |
| issn | 1680-7316 1680-7324 |
| language | English |
| last_indexed | 2024-04-13T12:12:43Z |
| publishDate | 2011-04-01 |
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| series | Atmospheric Chemistry and Physics |
| spelling | doaj.art-60d65831e4f34773b9de09a7a9fd5ecd2022-12-22T02:47:26ZengCopernicus PublicationsAtmospheric Chemistry and Physics1680-73161680-73242011-04-011183835384610.5194/acp-11-3835-2011Size-resolved and bulk activation properties of aerosols in the North China PlainZ. Z. DengC. S. ZhaoN. MaP. F. LiuL. RanW. Y. XuJ. ChenZ. LiangS. LiangM. Y. HuangX. C. MaQ. ZhangJ. N. QuanP. YanS. HenningK. MildenbergerE. SommerhageM. SchäferF. StratmannA. WiedensohlerSize-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 (<i>N</i><sub>CCN</sub>) and calculated CCN number concentration based on the aerosol number size distribution and size-resolved activation properties. <br><br> The observed CCN number concentration (<i>N</i><sub>CCN-obs</sub>) are higher than those observed in other locations than China, with average <i>N</i><sub>CCN-obs</sub> of roughly 2000, 3000, 6000, 10 000 and 13 000 cm<sup>−3</sup> at supersaturations of 0.056, 0.083, 0.17, 0.35 and 0.70%, respectively. An inferred critical dry diameter (<i>D</i><sub>m</sub>) is calculated based on the <i>N</i><sub>CCN-obs</sub> 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. <br><br> 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. <br><br> The calculated CCN number concentrations (<i>N</i><sub>CCN-calc</sub>) based on the size-resolved activation ratio and aerosol number size distribution correlate well with the <i>N</i><sub>CCN-obs</sub>, and show an average overestimation of 19%. Sensitivity studies of the CCN closure show that the <i>N</i><sub>CCN</sub> 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.http://www.atmos-chem-phys.net/11/3835/2011/acp-11-3835-2011.pdf |
| spellingShingle | Z. Z. Deng C. S. Zhao N. Ma P. F. Liu L. Ran W. Y. Xu J. Chen Z. Liang S. Liang M. Y. Huang X. C. Ma Q. Zhang J. N. Quan P. Yan S. Henning K. Mildenberger E. Sommerhage M. Schäfer F. Stratmann A. Wiedensohler Size-resolved and bulk activation properties of aerosols in the North China Plain Atmospheric Chemistry and Physics |
| title | Size-resolved and bulk activation properties of aerosols in the North China Plain |
| title_full | Size-resolved and bulk activation properties of aerosols in the North China Plain |
| title_fullStr | Size-resolved and bulk activation properties of aerosols in the North China Plain |
| title_full_unstemmed | Size-resolved and bulk activation properties of aerosols in the North China Plain |
| title_short | Size-resolved and bulk activation properties of aerosols in the North China Plain |
| title_sort | size resolved and bulk activation properties of aerosols in the north china plain |
| url | http://www.atmos-chem-phys.net/11/3835/2011/acp-11-3835-2011.pdf |
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