Preprints
https://doi.org/10.5194/acp-2020-1273
https://doi.org/10.5194/acp-2020-1273

  08 Jan 2021

08 Jan 2021

Review status: a revised version of this preprint was accepted for the journal ACP and is expected to appear here in due course.

Lidar vertical observation network and data assimilation reveal key processes driving the 3-D dynamic evolution of PM2.5 concentrations over the North China Plain

Yan Xiang1, Tianshu Zhang2,1, Chaoqun Ma3, Lihui Lv1, Jianguo Liu2, Wenqing Liu2,1, and Yafang Cheng3 Yan Xiang et al.
  • 1Institutes of Physical Science and Information Technology, Anhui University, Hefei 230601, China
  • 2Key Laboratory of Environmental Optics and Technology, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei 230031, China
  • 3Minerva Research Group, Max Planck Institute for Chemistry, Mainz, Germany

Abstract. China has made great efforts to monitor and control air pollution in the past decade. Comprehensive characterization and understanding of pollutants in three-dimension (3-D) are, however, still lacking. Here, we used data from an observation network consisting of 13 aerosol lidars and more than 1000 ground observation stations, combined with a data assimilation technique, to conduct a comprehensive analysis of an extreme heavy aerosol pollution (HAP) over the North China Plain (NCP) from November–December 2017. During the studied period, the maximum hourly mass concentration of surface PM2.5 reached ~390 μg m−3. After assimilation, the correlation between model results and the independent observation sub-dataset was ~50 % higher than the that without the assimilation, and the root mean square error was reduced by ~40 %. From pollution development to dissipation, we divided the HAP in the NCP (especially in Beijing) into four phases – an early phase (EP), a transport phase (TP), an accumulation phase (AP), and a removal phase (RP). We then analyzed the evolutionary characteristics of PM2.5 concentration during different phases on the surface and in 3-D space. We found that the particles were mainly transported from south to north at a height of 1–2 km (during EP and RP) and near the surface (during TP and AP). The amounts of PM2.5 advected into Beijing with the maximum transport flux intensity (TFI) were through the pathways in the relative order of the southwest > southeast > east pathways. The dissipation of PM2.5 in the RP stage (with negative TFI) was mainly from north to south, with an average transport height of ~1 km above the surface. Our results quantified the multi-dimensional distribution and evolution of PM2.5 concentration over the NCP, which may help policymakers develop efficient air pollution control strategies.

Yan Xiang et al.

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on acp-2020-1273', Anonymous Referee #1, 19 Jan 2021
  • RC2: 'Comment on acp-2020-1273', Anonymous Referee #2, 14 Feb 2021

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on acp-2020-1273', Anonymous Referee #1, 19 Jan 2021
  • RC2: 'Comment on acp-2020-1273', Anonymous Referee #2, 14 Feb 2021

Yan Xiang et al.

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Short summary
For the first time, a vertical observation network consisting of 13 aerosol lidars and more than 1000 ground observation stations, combined with a data assimilation technique, to reveal key processes driving the 3-D dynamic evolution of PM2.5 concentrations during an extreme heavy aerosol pollution on the North China Plain.
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