Modeling of Turbulence in Stable Layers and Forecasting of Pollution Episodes

1986 ◽  
pp. 277-289
Author(s):  
Jean-Michel Fage ◽  
Jean-François Soulier
Keyword(s):  
Pollution Episodes

Extreme heat and acute air pollution episodes: A need for joint public health warnings?

2021 ◽  
Vol 249 ◽  
pp. 118249
Author(s):  
Mathilde Pascal ◽  
Vérène Wagner ◽  
Anna Alari ◽  
Magali Corso ◽  
Alain Le Tertre
Keyword(s):  
Public Health ◽  
Air Pollution ◽  
Extreme Heat ◽  
Health Warnings ◽  
Air Pollution Episodes ◽  
Pollution Episodes

scholarly journals Nitrate-dominated PM<sub>2.5</sub> and elevation of particle pH observed in urban Beijing during the winter of 2017

2020 ◽  
Vol 20 (8) ◽  
pp. 5019-5033 ◽  
Author(s):  
Yuning Xie ◽  
Gehui Wang ◽  
Xinpei Wang ◽  
Jianmin Chen ◽  
Yubao Chen ◽  
...  
Keyword(s):  
Atmospheric Aerosols ◽  
Ammonia Concentration ◽  
Historical Record ◽  
Molar Ratio ◽  
Effective Control ◽  
Nitrate Content ◽  
Chinese Government ◽  
Low Level ◽  
The Impact ◽  
Pollution Episodes

Abstract. The Chinese government has exerted strict emission controls to mitigate air pollution since 2013, which has resulted in significant decreases in the concentrations of air pollutants such as SO2. Strict pollution control actions also reduced the average PM2.5 concentration to the low level of 39.7 µg m−3 in urban Beijing during the winter of 2017. To investigate the impact of such changes on the physiochemical properties of atmospheric aerosols in China, we conducted a comprehensive observation focusing on PM2.5 in Beijing during the winter of 2017. Compared with the historical record (2014–2017), SO2 decreased to the low level of 3.2 ppbv in the winter of 2017, but the NO2 level was still high (21.4 ppbv in the winter of 2017). Accordingly, the contribution of nitrate (23.0 µg m−3) to PM2.5 far exceeded that of sulfate (13.1 µg m−3) during the pollution episodes, resulting in a significant increase in the nitrate-to-sulfate molar ratio. The thermodynamic model (ISORROPIA II) calculation results showed that during the PM2.5 pollution episodes particle pH increased from 4.4 (moderate acidic) to 5.4 (more neutralized) when the molar ratio of nitrate to sulfate increased from 1 to 5, indicating that aerosols were more neutralized as the nitrate content elevated. Controlled variable tests showed that the pH elevation should be attributed to nitrate fraction increase other than crustal ion and ammonia concentration increases. Based on the results of sensitivity tests, future prediction for the particle acidity change was discussed. We found that nitrate-rich particles in Beijing at low and moderate humid conditions (RH: 20 %–50 %) can absorb twice the amount of water that sulfate-rich particles can, and the nitrate and ammonia with higher levels have synergetic effects, rapidly elevating particle pH to merely neutral (above 5.6). As moderate haze events might occur more frequently under abundant ammonia and nitrate-dominated PM2.5 conditions, the major chemical processes during haze events and the control target should be re-evaluated to obtain the most effective control strategy.

Evaluation of regional transport of PM2.5 during severe atmospheric pollution episodes in the western Yangtze River Delta, China

2021 ◽  
Vol 293 ◽  
pp. 112827
Author(s):  
Ishaq Dimeji Sulaymon ◽  
Yuanxun Zhang ◽  
Jianlin Hu ◽  
Philip K. Hopke ◽  
Yang Zhang ◽  
...  
Keyword(s):  
Atmospheric Pollution ◽  
Yangtze River ◽  
Yangtze River Delta ◽  
River Delta ◽  
Regional Transport ◽  
Pollution Episodes

Comparisons of two serious air pollution episodes in winter and summer in Beijing

2018 ◽  
Vol 69 ◽  
pp. 141-154 ◽  
Author(s):  
Nianliang Cheng ◽  
Yunting Li ◽  
Bingfen Cheng ◽  
Xin Wang ◽  
Fan Meng ◽  
...  
Keyword(s):  
Air Pollution ◽  
Air Pollution Episodes ◽  
Pollution Episodes

scholarly journals A Further Study of High Air Pollution Episodes in Taiwan Using the Microwave Temperature Profiler (MTP-5HE)

2006 ◽  
Vol 49 (1) ◽  
pp. 60-64 ◽  
Author(s):  
Che-Ming CHANG ◽  
Long-Nan CHANG ◽  
Hui-Chuan HSIAO ◽  
Fang-Chuan LU ◽  
Ping-Fei SHIEH ◽  
...  
Keyword(s):  
Air Pollution ◽  
Temperature Profiler ◽  
Air Pollution Episodes ◽  
Pollution Episodes

Investigating the occurrence, likelihood and regional variability of extreme ozone pollution episodes across the UK

2021 ◽  
Author(s):  
Lily Gouldsbrough ◽  
Ryan Hossaini ◽  
Emma Eastoe ◽  
Paul J. Young
Keyword(s):  
Surface Ozone ◽  
Extreme Value Analysis ◽  
Daily Maximum ◽  
Monitoring Site ◽  
Ozone Pollution ◽  
Threshold Method ◽  
Regional Variability ◽  
Value Analysis ◽  
The Uk ◽  
Pollution Episodes

&lt;p&gt;Warm summer temperatures provide ideal conditions for the occurrence of extreme ground level ozone pollution episodes. Given the well-established negative impacts of ozone on human and plant health, understanding and attributing these extreme events is of importance to the scientific and wider community, particularly as heatwaves may become more frequent due to climate change. Extreme Value Analysis provides a powerful and flexible framework in which to statistically model unusually large observed values of ozone extracted from historical data. Here, a temperature dependent Peaks-Over-Threshold method based upon the Generalised Pareto Distribution is used to carry out a regional comparison of extreme ozone pollution episodes within the UK. Our analysis uses surface ozone observations from the UK&amp;#8217;s extensive Automatic Urban and Rural Network. The statistical model was used to quantify the frequency and magnitude of extreme ozone events, including a probabilistic assessment of exceeding UK public health thresholds, conditional on temperature. Return levels are provided for each monitoring site demonstrating the expected future projections of extreme ozone pollution events across the UK. We find that across UK rural background sites, return periods for a daily maximum 8-hr ozone level of 100 ug/m3 (a 'moderate' level of air pollution in the UK's Air Quality Index) range from 32-147 days, based on analysis of the data in the decade 2010-2019. Similarly, for urban background sites the range is 36-869 days. An analysis of the spatio temporal variability in UK ozone extremes, along with their temperature dependence, will be presented.&lt;/p&gt;

scholarly journals Characteristics of Haze Pollution Episodes and Analysis of a Typical Winter Haze Process in Shanghai

2016 ◽  
Vol 16 (7) ◽  
pp. 1625-1637 ◽  
Author(s):  
Mengfei Zhao ◽  
Guangli Xiu ◽  
Ting Qiao ◽  
Yulan Li ◽  
Jianzhen Yu
Keyword(s):  
Haze Pollution ◽  
Pollution Episodes
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