Effects of different stagnant meteorological conditions on aerosol chemistry and regional transport changes in Beijing, China

2021 ◽  
pp. 118483
Author(s):  
Jiayun Li ◽  
Wenkang Gao ◽  
Liming Cao ◽  
Lingyan He ◽  
Xinghua Zhang ◽  
...  
Keyword(s):  
Meteorological Conditions ◽  
Aerosol Chemistry ◽  
Regional Transport ◽  
Beijing China

scholarly journals The Occurrence of Heavy Air Pollution during the COVID-19 Outbreak in Beijing, China: Roles of Emission Reduction, Meteorological Conditions, and Regional Transport

2021 ◽  
Vol 13 (21) ◽  
pp. 12312
Author(s):  
Xiao Yan ◽  
Aijun Shi ◽  
Jingyuan Cao ◽  
Tingting Li ◽  
Xuesong Sun ◽  
...  
Keyword(s):  
Air Pollution ◽  
Meteorological Conditions ◽  
Joint Control ◽  
Regional Transport ◽  
Regional Sources ◽  
Higher Temperature ◽  
Beijing China ◽  
Epidemic Risk ◽  
Air Pollution Episodes ◽  
Pollution Episodes

To prevent the spread of coronavirus disease (COVID-19) and mitigate the epidemic risk, strict lockdown measures were implemented in Beijing during the quarantine period, significantly reducing human activities. However, severe air pollution episodes occurred frequently in Beijing. To explore the occurrence of severe air pollution during the quarantine period, the impacts of emission reductions, meteorological conditions, and regional transport on heavy air pollution were individually evaluated using the Community Multiscale Air Quality (CMAQ) model. Observations showed that the more unfavorable meteorological conditions which occurred during the pandemic as compared to the corresponding 2019 levels, including higher temperature, relative humidity, and frequency of strong southerly winds, and lower HPBL, led to an increase in PM2.5 concentrations. The model results also showed that the meteorological conditions in February 2020 favored PM2.5 formation. The PM2.5 concentrations were mainly dominated by regional transport, which became more significant in the quarantine period than in 2019, suggesting the importance of joint control on regional sources for reducing heavy air pollution. This study highlights that, although the emissions in Beijing and surrounding regions were largely reduced during the quarantine period, severe air pollution in Beijing did not reduce due to the unfavorable meteorological conditions.

scholarly journals On the multiday haze in the Asian continental outflow: the important role of synoptic conditions combined with regional and local sources

2017 ◽  
Vol 17 (15) ◽  
pp. 9311-9332 ◽  
Author(s):  
Jihoon Seo ◽  
Jin Young Kim ◽  
Daeok Youn ◽  
Ji Yi Lee ◽  
Hwajin Kim ◽  
...  
Keyword(s):  
Meteorological Factors ◽  
Early Stage ◽  
Meteorological Conditions ◽  
The Yellow Sea ◽  
Regional Transport ◽  
Local Sources ◽  
Haze Episode ◽  
High Concentrations ◽  
Continental Outflow ◽  
Local Emissions

Abstract. The air quality of the megacities in populated and industrialized regions like East Asia is affected by both local and regional emission sources. The combined effect of regional transport and local emissions on multiday haze was investigated through a synthetic analysis of PM2. 5 sampled at both an urban site in Seoul, South Korea and an upwind background site on Deokjeok Island over the Yellow Sea during a severe multiday haze episode in late February 2014. Inorganic components and carbonaceous species of daily PM2. 5 samples were measured, and gaseous pollutants, local meteorological factors, and synoptic meteorological conditions were also determined. A dominance of fine-mode particles (PM2. 5 ∕ PM10  ∼  0.8), a large secondary inorganic fraction (76 %), high OC ∕ EC (> 7), and highly oxidized aerosols (oxygen-to-carbon ratio of  ∼  0.6 and organic-mass-to-carbon ratio of  ∼  1.9) under relatively warm, humid, and stagnant conditions characterize the multiday haze episode in Seoul; however, the early and late stages of the episode show different chemical compositions of PM2. 5. High concentrations of sulfate in both Seoul and the upwind background in the early stage suggest a significant regional influence on the onset of the multiday haze. At the same time, high concentrations of nitrate and organic compounds in Seoul, which are local and highly correlated with meteorological factors, suggest the contribution of local emissions and secondary formation under stagnant meteorological conditions to the haze. A slow eastward-moving high-pressure system from southern China to the East China Sea induces the regional transport of aerosols and potential gaseous precursors for secondary aerosols from the North China Plain in the early stage but provides stagnant conditions conducive to the accumulation and the local formation of aerosols in the late stage. A blocking ridge over Alaska that developed during the episode hinders the zonal propagation of synoptic-scale systems and extends the haze period to several days. This study provides chemical insights into haze development sequentially by regional transport and local sources, and shows that the synoptic condition plays an important role in the dynamical evolution of long-lasting haze in the Asian continental outflow region.

Impacts of regional transport on black carbon in Huairou, Beijing, China

2017 ◽  
Vol 221 ◽  
pp. 75-84 ◽  
Author(s):  
Yuqin Wang ◽  
Benjamin de Foy ◽  
James J. Schauer ◽  
Michael R. Olson ◽  
Yang Zhang ◽  
...  
Keyword(s):  
Black Carbon ◽  
Regional Transport ◽  
Beijing China

Long-term variation of black carbon and PM2.5 in Beijing, China with respect to meteorological conditions and governmental measures

2016 ◽  
Vol 212 ◽  
pp. 269-278 ◽  
Author(s):  
Yuan Chen ◽  
Nina Schleicher ◽  
Mathieu Fricker ◽  
Kuang Cen ◽  
Xiu-li Liu ◽  
...  
Keyword(s):  
Black Carbon ◽  
Meteorological Conditions ◽  
Term Variation ◽  
Beijing China

scholarly journals Rapid transition in winter aerosol composition in Beijing from 2014 to 2017: response to clean air actions

2019 ◽  
Vol 19 (17) ◽  
pp. 11485-11499 ◽  
Author(s):  
Haiyan Li ◽  
Jing Cheng ◽  
Qiang Zhang ◽  
Bo Zheng ◽  
Yuxuan Zhang ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Coal Combustion ◽  
Transport Model ◽  
Chemical Transport ◽  
Meteorological Conditions ◽  
Chemical Transport Model ◽  
Aerosol Chemistry ◽  
Aerosol Composition ◽  
Clean Air ◽  
Rapid Transition

Abstract. The clean air actions implemented by the Chinese government in 2013 have led to significantly improved air quality in Beijing. In this work, we combined the in situ measurements of the chemical components of submicron particles (PM1) in Beijing during the winters of 2014 and 2017 and a regional chemical transport model to investigate the impact of clean air actions on aerosol chemistry and quantify the relative contributions of anthropogenic emissions, meteorological conditions, and regional transport to the changes in aerosol chemical composition from 2014 to 2017. We found that the average PM1 concentration in winter in Beijing decreased by 49.5 % from 2014 to 2017 (from 66.2 to 33.4 µg m−3). Sulfate exhibited a much larger decline than nitrate and ammonium, which led to a rapid transition from sulfate-driven to nitrate-driven aerosol pollution during the wintertime. Organic aerosol (OA), especially coal combustion OA, and black carbon also showed large decreasing rates, indicating the effective emission control of coal combustion and biomass burning. The decreased sulfate contribution and increased nitrate fraction were highly consistent with the much faster emission reductions in sulfur dioxide (SO2) due to phasing out coal in Beijing compared to reduction in nitrogen oxides emissions estimated by bottom-up inventory. The chemical transport model simulations with these emission estimates reproduced the relative changes in aerosol composition and suggested that the reduced emissions in Beijing and its surrounding regions played a dominant role. The variations in meteorological conditions and regional transport contributed much less to the changes in aerosol concentration and its chemical composition during 2014–2017 compared to the decreasing emissions. Finally, we speculated that changes in precursor emissions possibly altered the aerosol formation mechanisms based on ambient observations. The observed explosive growth of sulfate at a relative humidity (RH) greater than 50 % in 2014 was delayed to a higher RH of 70 % in 2017, which was likely caused by the suppressed sulfate formation through heterogeneous reactions due to the decrease in SO2 emissions. Thermodynamic simulations showed that the decreased sulfate and nitrate concentrations have lowered the aerosol water content, particle acidity, and ammonium particle fraction. The results in this study demonstrate the response of aerosol chemistry to the stringent clean air actions and identify that the anthropogenic emission reductions are a major driver, which could help to further guide air pollution control strategies in China.

scholarly journals Insights into aerosol chemistry during the 2015 China victory day parade: results from simultaneous measurements at ground level and 260 m in Beijing

2016 ◽  
Author(s):  
Jian Zhao ◽  
Wei Du ◽  
Yingjie Zhang ◽  
Qingqing Wang ◽  
Chen Chen ◽  
...  
Keyword(s):  
Control Period ◽  
Ground Level ◽  
Meteorological Conditions ◽  
Formation Mechanisms ◽  
Aerosol Chemistry ◽  
Positive Matrix ◽  
Aerosol Mass Spectrometer ◽  
Inorganic Aerosols ◽  
Aerosol Mass ◽  
Emission Controls

Abstract. Strict emission controls were implemented in Beijing and adjacent provinces to ensure good air quality during the 2015 China victory day parade. Here we conducted synchronous measurements of submicron aerosols (PM1) at ground level and 260 m on a meteorological tower by using a High-Resolution Aerosol Mass Spectrometer and an Aerosol Chemical Speciation Monitor, respectively, in Beijing from 22 August to 30 September. Our results showed that the average PM1 concentrations are 19.3 and 14.8 µg m−3 at ground level and 260 m, respectively, during the control period (20 August–3 September), which are 57 % and 50 % lower than those after the control period (4–30 September). Organic aerosols (OA) dominated PM1 during the control period at both ground level and 260 m (55 % and 53 %, respectively), while its contribution showed substantial decreases (~ 40 %) associated with an increase in secondary inorganic aerosols (SIA) after the parade indicating a larger impact of emission controls on SIA than OA. Positive matrix factorization of OA further illustrated that primary OA (POA) showed similar decreases as secondary OA (SOA) at both ground level (40 % vs. 42 %) and 260 m (35 % vs. 36 %). However, we also observed significant changes in SOA composition. While the more oxidized SOA showed a large decrease by 75 %, the less oxidized SOA was comparable during (5.6 µg m−3) and after the control periods (6.5 µg m−3). Our results demonstrated that the changes in meteorological conditions and PM loadings have affected SOA formation mechanisms, and the photochemical production of fresh SOA was more important during the control period. By isolating the influences of meteorological conditions and footprint regions in polluted episodes, we found that regional emission controls on average reduced PM levels by 44–45 %, and the reductions were close among SIA, SOA and POA at 260 m, whereas primary species showed relatively more reductions (55–67 %) than secondary aerosol species (33 %–44 %) at ground level.

scholarly journals Influences of characteristic meteorological conditions on atmospheric carbonyls in Beijing, China

2009 ◽  
Vol 93 (4) ◽  
pp. 913-919 ◽  
Author(s):  
Xiaobing Pang ◽  
Yujing Mu ◽  
Xinqing Lee ◽  
Yujie Zhang ◽  
Zhu Xu
Keyword(s):  
Meteorological Conditions ◽  
Beijing China

scholarly journals Assessing the formation and evolution mechanisms of severe haze pollution in the Beijing–Tianjin–Hebei region using process analysis

2019 ◽  
Vol 19 (16) ◽  
pp. 10845-10864 ◽  
Author(s):  
Lei Chen ◽  
Jia Zhu ◽  
Hong Liao ◽  
Yi Gao ◽  
Yulu Qiu ◽  
...  
Keyword(s):  
Process Analysis ◽  
Vertical Mixing ◽  
Aerosol Chemistry ◽  
Regional Transport ◽  
Near Surface ◽  
Stage 1 ◽  
Local Emissions ◽  
Bth Region ◽  
Aerosol Radiative ◽  
Pm2.5 Concentration

Abstract. Fine-particle pollution associated with haze threatens human health, especially in the North China Plain region, where extremely high PM2.5 concentrations are frequently observed during winter. In this study, the Weather Research and Forecasting with Chemistry (WRF-Chem) model coupled with an improved integrated process analysis scheme was used to investigate the formation and evolution mechanisms of a haze event over the Beijing–Tianjin–Hebei (BTH) region in December 2015; this included an examination of the contributions of local emissions and regional transport to the PM2.5 concentration in the BTH area, and the contributions of each detailed physical or chemical process to the variations in the PM2.5 concentration. The mechanisms influencing aerosol radiative forcing (including aerosol direct and indirect effects) were also examined by using process analysis. During the aerosol accumulation stage (16–22 December, Stage 1), the near-surface PM2.5 concentration in the BTH region increased from 24.2 to 289.8 µg m−3, with the contributions of regional transport increasing from 12 % to 40 %, while the contribution of local emissions decreased from 59 % to 38 %. During the aerosol dispersion stage (23–27 December, Stage 2), the average concentration of PM2.5 was 107.9 µg m−3, which was contributed by local emissions (51 %) and regional transport (24 %). The 24 h change (23:00 minus 00:00 LST) in the near-surface PM2.5 concentration was +43.9 µg m−3 during Stage 1 and −41.5 µg m−3 during Stage 2. The contributions of aerosol chemistry, advection, and vertical mixing to the 24 h change were +29.6 (+17.9) µg m−3, −71.8 (−103.6) µg m−3, and −177.3 (−221.6) µg m−3 during Stage 1 (Stage 2), respectively. Small differences in the contributions of other processes were found between Stage 1 and Stage 2. Therefore, the PM2.5 increase over the BTH region during the haze formation stage was mainly attributed to strong production by the aerosol chemistry process and weak removal by the advection and vertical mixing processes. When aerosol radiative feedback was considered, the 24 h PM2.5 increase was enhanced by 4.8 µg m−3 during Stage 1, which could be mainly attributed to the contributions of the vertical mixing process (+22.5 µg m−3), the advection process (−19.6 µg m−3), and the aerosol chemistry process (+1.2 µg m−3). The restrained vertical mixing was the primary reason for the enhancement in the near-surface PM2.5 increase when aerosol radiative forcing was considered.

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