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Analysis of influential factors for the relationship between PM_(2.5) and AOD in Beijing

Zheng, Caiwang and Zhao, Chuanfeng and Zhu, Yannian and Wang, Yang and Shi, Xiaoqin and Wu, Xiaolin and Chen, Tianmeng and Wu, Fang and Qiu, Yanmei (2017) Analysis of influential factors for the relationship between PM_(2.5) and AOD in Beijing. Atmospheric Chemistry and Physics, 17 (21). pp. 13473-13489. ISSN 1680-7324. doi:10.5194/acp-17-13473-2017.

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The relationship between aerosol optical depth (AOD) and PM_(2.5) is often investigated in order to obtain surface PM_(2.5) from satellite observation of AOD with a broad area coverage. However, various factors could affect the AOD–PM_(2.5) regressions. Using both ground and satellite observations in Beijing from 2011 to 2015, this study analyzes the influential factors including the aerosol type, relative humidity (RH), planetary boundary layer height (PBLH), wind speed and direction, and the vertical structure of aerosol distribution. The ratio of PM_(2.5) to AOD, which is defined as η, and the square of their correlation coefficient (R^2) have been examined. It shows that η varies from 54.32 to 183.14, 87.32 to 104.79, 95.13 to 163.52, and 1.23 to 235.08 µg m^(−3) with aerosol type in spring, summer, fall, and winter, respectively. η is smaller for scattering-dominant aerosols than for absorbing-dominant aerosols, and smaller for coarse-mode aerosols than for fine-mode aerosols. Both RH and PBLH affect the η value significantly. The higher the RH, the smaller the η, and the higher the PBLH, the smaller the η. For AOD and PM2.5 data with the correction of RH and PBLH compared to those without, R^2 of monthly averaged PM_(2.5) and AOD at 14:00 LT increases from 0.63 to 0.76, and R^2 of multi-year averaged PM_(2.5) and AOD by time of day increases from 0.01 to 0.93, 0.24 to 0.84, 0.85 to 0.91, and 0.84 to 0.93 in four seasons respectively. Wind direction is a key factor for the transport and spatial–temporal distribution of aerosols originated from different sources with distinctive physicochemical characteristics. Similar to the variation in AOD and PM_(2.5), η also decreases with the increasing surface wind speed, indicating that the contribution of surface PM_(2.5) concentrations to AOD decreases with surface wind speed. The vertical structure of aerosol exhibits a remarkable change with seasons, with most particles concentrated within about 500 m in summer and within 150 m in winter. Compared to the AOD of the whole atmosphere, AOD below 500 m has a better correlation with PM_(2.5), for which R^2 is 0.77. This study suggests that all the above influential factors should be considered when we investigate the AOD–PM_(2.5) relationships.

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URLURL TypeDescription
Zhao, Chuanfeng0000-0002-5196-3996
Zhu, Yannian0000-0002-8371-1830
Wang, Yang0000-0003-4492-2974
Additional Information:© 2017 Author(s). This work is distributed under the Creative Commons Attribution 3.0 License. Published by Copernicus Publications on behalf of the European Geosciences Union. Received: 27 Dec 2016 – Discussion started: 17 Feb 2017. Revised: 14 Sep 2017 – Accepted: 01 Oct 2017 – Published: 13 Nov 2017. This work was supported by the National Natural Science Foundation of China (NSFC: grant 41575143), the Ministry of Science and Technology of China (grants 2013CB955802), the China “1000 Plan” young scholar program, the Fundamental Research Funds for the Central Universities (2017EYT18, 312231103), and the Chinese Program for New Century Excellent Talents in University (NCET). We extend sincerest thanks to the AERONET, MODIS, and CALIPSO teams for their datasets. The CALIPSO data were obtained from the NASA Langley Research Center Atmospheric Science Data Center. We also extend special thanks to the US Embassy and CMA for providing the PM_(2.5) data and meteorological data, respectively. We also thank the five anonymous referees for their valuable comments. The authors declare that they have no conflict of interest.
Funding AgencyGrant Number
National Natural Science Foundation of China41575143
Ministry of Science and Technology (China)2013CB955802
China “1000 Plan” Young Scholar ProgramUNSPECIFIED
Fundamental Research Funds for the Central Universities2017EYT18
Fundamental Research Funds for the Central Universities312231103
Chinese Program for New Century Excellent Talents in University (NCET)UNSPECIFIED
Issue or Number:21
Record Number:CaltechAUTHORS:20171130-102533758
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Official Citation:Zheng, C., Zhao, C., Zhu, Y., Wang, Y., Shi, X., Wu, X., Chen, T., Wu, F., and Qiu, Y.: Analysis of influential factors for the relationship between PM2.5 and AOD in Beijing, Atmos. Chem. Phys., 17, 13473-13489,, 2017
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:83595
Deposited By: Tony Diaz
Deposited On:30 Nov 2017 18:39
Last Modified:15 Nov 2021 20:12

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