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Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
Atmos. Chem. Phys., 17, 3891-3903, 2017
https://doi.org/10.5194/acp-17-3891-2017
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
21 Mar 2017
Lower tropospheric distributions of O3 and aerosol over Raoyang, a rural site in the North China Plain
Rui Wang1, Xiaobin Xu1, Shihui Jia1,a, Ruisheng Ma2, Liang Ran3, Zhaoze Deng3, Weili Lin4, Ying Wang1, and Zhiqiang Ma5 1State Key Laboratory of Severe Weather & Key Laboratory for Atmospheric Chemistry of China Meteorological Administration, Chinese Academy of Meteorological Sciences, Beijing, China
2Guangxi Meteorological Disaster Mitigation Institute, Nanning, Guangxi, China
3Key Laboratory of Middle Atmosphere and Global Environment Observation, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, China
4Meteorological Observation Center, China Meteorological Administration, Beijing, China
5Institute of Urban Meteorology, China Meteorological Administration, Beijing, China
anow at: School of Environment and Energy, South China University of Technology, Guangzhou, Guangdong, China
Abstract. The North China Plain (NCP) has become one of the most polluted regions in China, with the rapidly increasing economic growth in the past decades. High concentrations of ambient O3 and aerosol have been observed at urban as well as rural sites in the NCP. Most of the in situ observations of air pollutants have been conducted near the ground so that current knowledge about the vertical distributions of tropospheric O3 and aerosol over the NCP region is still limited. In this study, vertical profiles of O3 and size-resolved aerosol concentrations below 2.5 km were measured in summer 2014 over a rural site in the NCP, using an unmanned aerial vehicle (UAV) equipped with miniature analyzers. In addition, vertical profiles of aerosol scattering property in the lower troposphere and vertical profiles of O3 below 1 km were also observed at the site using a lidar and tethered balloon, respectively. The depths of the mixed layer and residual layer were determined according to the vertical gradients of lidar particle extinction and aerosol number concentration. Average O3 and size-resolved aerosol number concentration in both the mixed and residual layer were obtained from the data observed in seven UAV flights. The results show that during most of the flights the O3 levels above the top of mixed layer were higher than those below. Such a positive gradient in the vertical distribution of O3 makes the residual layer an important source of O3 in the mixed layer, particularly during the morning when the top of mixed layer is rapidly elevated. In contrast to O3, aerosol number concentration was normally higher in the mixed layer than in the residual layer, particularly in the early morning. Aerosol particles were overwhelmingly distributed in the size range  <  1 µm, showing slight differences between the mixed and residual layers. Our measurements confirm that the lower troposphere over the rural area of the NCP is largely impacted by anthropogenic pollutants locally emitted or transported from urban areas. Compared with the historic O3 vertical profiles over Beijing from the Measurement of Ozone and Water Vapor by Airbus In-Service Aircraft (MOZAIC), a strong increase in O3 can be found at all heights below 2.5 km in the decade from 2004 to 2014, with the largest enhancement of about 41.6 ppb. This indicates that the lower troposphere over the northern part of the NCP has experienced rapidly worsening photochemical pollution. This worsening trend in photochemical pollution deserves more attention in the future.
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Citation: Wang, R., Xu, X., Jia, S., Ma, R., Ran, L., Deng, Z., Lin, W., Wang, Y., and Ma, Z.: Lower tropospheric distributions of O3 and aerosol over Raoyang, a rural site in the North China Plain, Atmos. Chem. Phys., 17, 3891-3903, https://doi.org/10.5194/acp-17-3891-2017, 2017.
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Short summary
Knowledge about the vertical distributions of air pollutants is limited. We present first unmanned aerial vehicle (UAV) observations of vertical profiles of O3 and size-resolved aerosol number concentrations over a rural site in the North China Plain. We show the determination of mixed and residual layer depth and characterization of diurnal O3 and aerosol number concentrations in the mixed and residual layer. We confirm a rapid increase of O3 in the lower troposphere during the recent decade.
Knowledge about the vertical distributions of air pollutants is limited. We present first...
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