Boundary-layer features and regional transport process of an extreme haze pollution event in Nanjing, China

2018 ◽  
Vol 9 (6) ◽  
pp. 1088-1099 ◽  
Author(s):  
Duanyang Liu ◽  
Wenlian Yan ◽  
Zhiming Kang ◽  
Anning Liu ◽  
Yi Zhu
Keyword(s):  
Boundary Layer ◽  
Transport Process ◽  
Regional Transport ◽  
Haze Pollution ◽  
Pollution Event

Vertical structure of the transport fluxes of aerosol and its precursors on the southwest transport pathway in the Beijing-Tianjin-Hebei region

2020 ◽  
Author(s):  
Qihou Hu ◽  
Cheng Liu ◽  
Xiangguang Ji ◽  
Ting Liu ◽  
Yizhi Zhu
Keyword(s):  
Boundary Layer ◽  
Air Pollutants ◽  
Source Region ◽  
Optical Absorption Spectroscopy ◽  
Vertical Profiles ◽  
Transport Pathway ◽  
Regional Transport ◽  
Surface Observation ◽  
Haze Pollution ◽  
Bth Region

<p>Haze pollution caused by atmospheric aerosols has become one of the most severe environmental problems in China, especially in the Beijing-Tianjin-Hebei (BTH) region. Air pollution is not caused by local emission and secondary formation of air pollutants, but also affected by transport from its surrounding areas. A number of studies with respect to the regional transport of air pollutants in the BTH region have been conducted based on surface observation. However, owing to the inhomogeneous vertical distribution of air pollutants and meteorological conditions, the vertical profiles of transport fluxes should be considered for a comprehensive understanding of regional transport. In this study, the vertical profiles of aerosol and its precursor indicators HCHO, NO<sub>2</sub> and SO<sub>2</sub> were observed by ground-based multi-axis differential optical absorption spectroscopy (MAX-DOAS) at the Nancheng (NC) site in suburban Beijing on the southwest transport pathway. The profiles of the pollutants varied with seasons with more aerosols concentrated at the surface in the winter. Through potential source contribution function (PSCF) analysis, southwest transport pathway was determined as the main transport source region, particularly for air pollutants in the middle and upper boundary layer. The transport fluxes of air pollutants at each vertical layer on the southwest-northeast direction were estimated combining with wind field simulated by WRF-Chem modeling. The average fluxes of the measured pollutants from June 2018 to May 2019 during the southwest transport (from southwest to northeast) were all higher than those during the northeast transport (from northeast to southwest), indicating net input of pollutants to urban Beijing from southwest transport pathway. Except for northwest transport of aerosols, the other maximum transport fluxes occurred at high altitudes instead of at the surface. The proportions of surface flux in the column flux for all the species during southwest transport were higher than those during northeast transport. Surface observation would overestimate the relative contribution from urban Beijing to southwest pathway and underestimate the contribution from southwest pathway to urban Beijing. Southwest transport played an important role on the developing stage of aerosol pollution in urban Beijing in the autumn and winter, and this transport mainly occurred in the middle boundary layer.</p>

scholarly journals Dome effect of black carbon and its key influencing factors: A one-dimensional modelling study

2017 ◽  
Author(s):  
Zilin Wang ◽  
Xin Huang ◽  
Aijun Ding
Keyword(s):  
Boundary Layer ◽  
Air Pollution ◽  
Black Carbon ◽  
Rural Areas ◽  
Land Surface ◽  
Critical Role ◽  
Aerosol Layer ◽  
Near Surface ◽  
Haze Pollution ◽  
The Impact

Abstract. Black carbon (BC) has been identified to play a critical role in aerosol-planet boundary layer (PBL) interaction and further deterioration of near-surface air pollution in megacities, which has been named as its dome effect. However, the impacts of key factors that influence this effect, such as the vertical distribution and aging processes of BC, and also the underlying land surface, have not been quantitatively explored yet. Here, based on available in-situ measurements of meteorology and atmospheric aerosols together with the meteorology-chemistry online coupled model, WRF-Chem, we conduct a set of parallel simulations to quantify the roles of these factors in influencing the BC's dome effect and surface haze pollution, and discuss the main implications of the results to air pollution mitigation in China. We found that the impact of BC on PBL is very sensitive to the altitude of aerosol layer. The upper level BC, especially those near the capping inversion, is more essential in suppressing the PBL height and weakening the turbulence mixing. The dome effect of BC tends to be significantly intensified as BC aerosol mixed with scattering aerosols during winter haze events, resulting in a decrease of PBL height by more than 25 %. In addition, the dome effect is more substantial (up to 15 %) in rural areas than that in the urban areas with the same BC loading, indicating an unexpected regional impact of such kind of effect to air quality in countryside. This study suggests that China's regional air pollution would greatly benefit from BC emission reductions, especially those from the elevated sources from the chimneys and also the domestic combustions in rural areas, through weakening the aerosol-boundary layer interactions that triggered by BC.

Investigation of the atmospheric boundary layer during an unexpected summertime persistent severe haze pollution period in Beijing

2019 ◽  
Vol 132 (1) ◽  
pp. 71-84
Author(s):  
Tingting Xu ◽  
Yu Song ◽  
Minsi Zhang ◽  
Mingxu Liu ◽  
Xuhui Cai ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Atmospheric Boundary Layer ◽  
Haze Pollution

scholarly journals Multiple technical observations of the atmospheric boundary layer structure of a red warning haze episode in Beijing

2019 ◽  
Author(s):  
Yu Shi ◽  
Fei Hu ◽  
Guangqiang Fan ◽  
Zhe Zhang
Keyword(s):  
Boundary Layer ◽  
Air Pollution ◽  
Atmospheric Boundary Layer ◽  
Extinction Coefficient ◽  
Layer Structure ◽  
Low Frequency ◽  
Inverse Correlation ◽  
Hygroscopic Growth ◽  
Boundary Layer Structure ◽  
Haze Pollution

Abstract. The study and control of air pollution need to detect the structure of atmospheric boundary layer (ABL) in order to understand the mechanism of interaction between atmospheric boundary layer and air pollution. However, when extreme pollution occurs, the detection of atmospheric boundary layer structure is very scarce. Beijing, the capital of China, has experienced a severe haze pollution in December 2016. The city issued its first red air pollution warning of this year (the highest PM2.5 concentration was later monitored to exceed 450 μg m−3). In this paper, the vertical profiles of wind, temperature, humidity and extinction coefficient (reflecting aerosol concentration), as well as ABL heights and turbulence quantities under heavy haze pollution are analyzed, with collected data from Lidar, wind profile radar (WPR), radiosonde, 325-meter meteorological tower (equipped with 7-layer supersonic anemometer and 15-layer low frequency wind, temperature and humidity sensors) and some other ground observations. ABL heights obtained by three different methods based on Lidar extinction coefficient data (Hc) are compared with the heights calculated from radiosonde temperature data (Hθ) and from WPR wind speed data (Hu). The results show that increase of water vapor has greatly promoted the hygroscopic growth of aerosols, the corresponding extinction coefficients also increased significantly. The PBL heights Hθ and Hu of heavy haze pollution day were generally lower than those of clean day, but Hc increased. Turbulent activities were great inhibited during haze pollution, time changes of both friction velocity (u*) and turbulent kinetic energy (TKE) have obvious inverse correlation with that of PM2.5. The results of this paper could provide some reference for the parameterization of the boundary layer height and turbulent diffusion process in the numerical model of severe air pollution.

scholarly journals Development of WRF/CUACE v1.0 model and its preliminary application in simulating air quality in China

2020 ◽  
Author(s):  
Lei Zhang ◽  
Sunling Gong ◽  
Tianliang Zhao ◽  
Chunhong Zhou ◽  
Yuesi Wang ◽  
...  
Keyword(s):  
Air Quality ◽  
Chemical Reactions ◽  
Atmospheric Chemistry ◽  
Eastern China ◽  
Weather Research And Forecasting ◽  
Deep Basin ◽  
China Meteorological Administration ◽  
The North ◽  
Haze Pollution ◽  
Pollution Event

Abstract. The development of chemical transport models with advanced physics and chemical schemes could improve air-quality forecasts. In this study, the China Meteorological Administration Unified Atmospheric Chemistry Environment (CUACE) model, a comprehensive chemistry module incorporating gaseous chemistry and a size-segregated multicomponent aerosol algorithm, was coupled to the Weather Research and Forecasting (WRF)-Chem framework using an interface procedure to build the WRF/CUACE v1.0 model. The latest version of CUACE includes an updated aerosol dry deposition scheme and the introduction of heterogeneous chemical reactions on aerosol surfaces. We evaluated the WRF/CUACE v1.0 model by simulating PM2.5, O3, and NO2 concentrations for January, April, July, and October (representing winter, spring, summer, and autumn, respectively) in 2013, 2015, and 2017 and comparing them with ground-based observations. Secondary inorganic aerosol simulations were also evaluated through a simulation of a heavy haze pollution event during 9–15 January 2019 in the North China Plain. The model well captured the variations of PM2.5, O3, and NO2 concentrations in all seasons in eastern China. However, it is difficult to accurately reproduce the variations of air pollutants over Sichuan Basin, due to its deep basin terrain. The sulfate and nitrate simulations are substantially improved by introducing heterogenous chemical reactions into the CUACE model (change in bias from −95.0 % to 4.1 % for sulfate and from 124.1 % to 96.0 % for nitrate). The development of the WRF/CUACE v1.0 model represents an important step towards improving air-quality modelling and forecasts in China.

scholarly journals Impacts of atmospheric vertical structures on transboundary aerosol transport from China to South Korea

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Hyo-Jung Lee ◽  
Hyun-Young Jo ◽  
Sang-Woo Kim ◽  
Moon-Soo Park ◽  
Cheol-Hee Kim
Keyword(s):  
Boundary Layer ◽  
Air Quality ◽  
South Korea ◽  
Long Range ◽  
Korean Peninsula ◽  
Ground Level ◽  
The Yellow Sea ◽  
Observation Data ◽  
Haze Pollution ◽  
High Concentrations

Abstract To forecast haze pollution episodes caused by high concentrations of long-range transported pollutants emitted in the areas upstream of South Korea, it is crucial to study and identify their behaviour. We analysed the three-dimensional air quality structure in Seoul using ground observation data and aerosol lidar measurements to identify vertical aerosol intrusion into the Korean Peninsula during the spring of 2016. The intrusions were particularly affected by the development of the atmospheric boundary layer (ABL) in the leeward regions. The nocturnal pollutant intrusion into the Korean peninsula via the Yellow Sea was examined using measured data. The pollutants first reached the area above the nocturnal boundary layer (548 ± 180 m) and approached ground level on the following day due to convective mixing depending on the convective ABL growth (1182 ± 540 m) in daytime. These intrusion mechanisms were mostly attributed to extremely high concentrations (i.e. >100 μg m−3) of fine particulate matter in the leeward regions, accounting for four of the total of six cases for which the warnings and alerts were issued in Seoul Metropolitan Area over a year-long period (2016). The horizontal and vertical pathways of the long-range transported pollutants and the atmospheric vertical structure were identified as key factors affecting the surface air quality concentration in the leeward regions.

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