气候变化领域集成服务门户(CCPortal): Dominant synoptic patterns associated with the decay process of PM2.5 pollution episodes around Beijing

CCPortal

DOI	10.5194/acp-21-2491-2021
	Dominant synoptic patterns associated with the decay process of PM2.5 pollution episodes around Beijing
	Wang X.; Zhang R.; Tan Y.; Yu W.
发表日期	2021
ISSN	1680-7316
起始页码	2491
结束页码	2508
卷号	21 期号:4
英文摘要	The variation in the concentrations of ambient PM2:5 (particles with an aerodynamic diameter less than 2.5 um) generally forms a continuous sawtooth cycle with a recurring smooth increase followed by a sharp decrease. The episode of abrupt decay of pollution is mostly meteorological in origin and is controlled by the passage of synoptic systems. One affordable and effective measure for quickly reducing PM2:5 concentrations in northern China is to wait for a strong wind to arrive. However, it is still unclear how strong the wind needs to be and exactly what kind of synoptic system most effectively results in the rapid decay of air pollution episodes. PM2:5 variations over the 28 pollution channel cities of the Beijing region are investigated to determine the mechanisms by which synoptic patterns affect the decay processes of pollution episodes. This work shows more obvious day-To-day variations in PM2:5 concentration in winter than in summer, which implies that wintertime PM2:5 variations are more sensitive to meteorological factors. There were 365 decay processes from January 2014 to March 2020, and 97 of them were related to the effective wet deposition. In total, 26%-43% of PM2:5 pollutant is removed by the wet deposition in different seasons. Two dominant circulation patterns are identified in summer. All the other three seasons have three circulation types (CTs), respectively. The three CTs in spring show the same patterns as those in autumn and winter. The circulation patterns beneficial to the decay processes all exhibit a higher-Than-normal surface wind speed, a negative relative humidity anomaly and net outflow of PM2:5 from the domain. In addition, CT1 in spring, autumn and winter is controlled by northeasterly wind and features the most significant horizontal net outflow of air pollutants and effective upward spread of air pollutants to the free atmosphere. CT2 is the most frequent CT in autumn and winter, with the highest wind speed from the northwest, highest boundary layer height (BLH) and lowest relative humidity among the three CTs, all of which are favorable for the reduction of PM2:5 concentrations. In CT3, strong vertical wind shear within the boundary layer enhances the mixing of surface air pollutants, which is the extra cleaning mechanism besides dry and clean air mass inflow. PM2:5 concentrations show significant decreases of more than 37 %, 41% and 27% after the passage of CT1, CT2 and CT3, respectively. A dry airflow with a positive BLH anomaly and the effective horizontal outflow of air pollutants are the main reasons for the abrupt decay phase in summer. PM2:5 concentrations after the decay process show a significant decreasing trend from 2014 to 2020, reflecting successful emission mitigation. Emission reductions have led to a 4.3-5.7 ugm-3 yr-1 decrease in PM2:5 concentrations in the 28 pollution channel cities of the Beijing region. © 2021 Association for Computing Machinery. All rights reserved.
语种	英语
scopus关键词	atmospheric pollution; boundary layer; concentration (composition); particulate matter; pollutant; relative humidity; synoptic meteorology; wind velocity; Beijing [China]; China
来源期刊	ATMOSPHERIC CHEMISTRY AND PHYSICS
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/247132
作者单位	Department of Atmospheric and Oceanic Sciences and Institute of Atmospheric Sciences, Fudan University, Shanghai, China; Big Data Institute for Carbon Emission and Environmental Pollution, Fudan University, Shanghai, China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai, China; Shanghai Ecological Forecasting and Remote Sensing Center, Shanghai, China
推荐引用方式 GB/T 7714	Wang X.,Zhang R.,Tan Y.,et al. Dominant synoptic patterns associated with the decay process of PM2.5 pollution episodes around Beijing[J],2021,21(4).
APA	Wang X.,Zhang R.,Tan Y.,&Yu W..(2021).Dominant synoptic patterns associated with the decay process of PM2.5 pollution episodes around Beijing.ATMOSPHERIC CHEMISTRY AND PHYSICS,21(4).
MLA	Wang X.,et al."Dominant synoptic patterns associated with the decay process of PM2.5 pollution episodes around Beijing".ATMOSPHERIC CHEMISTRY AND PHYSICS 21.4(2021).