Evaluating the contributions of changed meteorological conditions and emission to substantial reductions of PM2.5 concentration from winter 2016 to 2017 in Central and Eastern China

2020 ◽  
Vol 716 ◽  
pp. 136892 ◽  
Author(s):  
Wenjie Zhang ◽  
Hong Wang ◽  
Xiaoye Zhang ◽  
Yue Peng ◽  
Junting Zhong ◽  
...  
Keyword(s):  
Eastern China ◽  
Meteorological Conditions ◽  
Pm2.5 Concentration

scholarly journals Contribution of Meteorological Conditions to the Variation in Winter PM2.5 Concentrations from 2013 to 2019 in Middle-Eastern China

Atmosphere ◽  
2019 ◽  
Vol 10 (10) ◽  
pp. 563 ◽  
Author(s):  
Liu ◽  
Wang ◽  
Shen ◽  
Peng ◽  
Shi ◽  
...  
Keyword(s):  
Middle Eastern ◽  
Eastern China ◽  
Regional Scale ◽  
Winter Season ◽  
Meteorological Conditions ◽  
Pollutant Emissions ◽  
Circulation Index ◽  
Upper Level ◽  
Pollution Events ◽  
Pm2.5 Concentration

Severe air pollution events accompanied by high PM2.5 concentrations have been repeatedly observed in Middle-Eastern China since 2013 and decreased in recent years. The reason for this caused widespread attention. The month of January was selected to represent the winter season annual changes in the winter PM2.5 and meteorological conditions—including the upper-air meridional circulation index (MCI), winds at 700 and 850 hPa levels and surface meteorology—from 2013 to 2019. These conditions were analyzed to study the contribution of meteorology changing to the annual PM2.5 changing on the regional scale. Results show that, based on values of upper-level MCI, the years 2014, 2015, 2017, and 2019 were defined as meteorology-haze years and the years 2016 and 2018 were defined as meteorology-clean years. A change in meteorological conditions may lead to a 26% change in PM2.5 concentration between 2014 and 2013 (two meteorology-haze years) and 16–20% changes in PM2.5 concentration between meteorology-haze years and meteorology-clean years. Changes in pollutant emissions may cause 21–47% changes in PM2.5 concentration between each two meteorology-haze years. A comparison of two meteorology-clean years and pollutant emissions in 2018 may be reduced by 40% compared with 2016. Overall, changes in emissions had a greater influence on changes in PM2.5 compared with meteorological conditions.

scholarly journals Meteorological Variables and Synoptic Patterns Associated with Air Pollutions in Eastern China during 2013–2018

2020 ◽  
Vol 17 (7) ◽  
pp. 2528 ◽  
Author(s):  
Zhujun Dai ◽  
Duanyang Liu ◽  
Kun Yu ◽  
Lu Cao ◽  
Youshan Jiang
Keyword(s):  
Air Pollution ◽  
Eastern China ◽  
Meteorological Condition ◽  
Temperature Inversion ◽  
Meteorological Conditions ◽  
Meteorological Variables ◽  
Synoptic Situation ◽  
Factors Affecting ◽  
Air Pollutions ◽  
Meteorological Elements

Steady meteorological conditions are important external factors affecting air pollution. In order to analyze how adverse meteorological variables affect air pollution, surface synoptic situation patterns and meteorological conditions during heavy pollution episodes are discussed. The results showed that there were 78 RPHPDs (regional PM2.5 pollution days) in Jiangsu, with a decreasing trend year by year. Winter had the most stable meteorological conditions, thus most RPHPDs appeared in winter, followed by autumn and summer, with the least days in spring. RPHPDs were classified into three patterns, respectively, as equalized pressure (EQP), advancing edge of a cold front (ACF) and inverted trough of low pressure (INT) according to the SLP (sea level pressure). RPHPDs under EQP were the most (51%), followed by ACF (37%); INT was the minimum (12%). Using statistical methods and meteorological condition data on RPHPDs from 2013 to 2017 to deduce the thresholds and 2018 as an independent dataset to validate the proposed thresholds, the threshold values of meteorological elements are summarized as follows. The probability of RPHPDs without rain was above 92% with the daily and hourly precipitation of all RPHPDs below 2.1 mm and 0.8 mm. Wind speed, RHs, inversion intensity(ITI), height difference in the temperature inversion(ITK), the lower height of temperature inversion (LHTI) and mixed-layer height (MLH) in terms of 25%–75% high probability range were respectively within 0.5–3.6 m s−1, 55%–92%, 0.7–4.0 °C 100 m −1, 42–576 m, 3–570 m, 200–1200 m. Two conditions should be considered: whether the pattern was EQP, ACF or INT and whether the eight meteorological elements are within the thresholds. If both criteria are met, PM2.5 particles tend to accumulate and air pollution diffusion conditions are poor. Unfavorable meteorological conditions are the necessary, but not sufficient condition for RPHPDs.

scholarly journals Impacts of meteorology and emissions on surface ozone increases over Central Eastern China between 2003 and 2015

2018 ◽  
Author(s):  
Lei Sun ◽  
Likun Xue ◽  
Yuhang Wang ◽  
Longlei Li ◽  
Jintai Lin ◽  
...  
Keyword(s):  
Urban Areas ◽  
Control Strategies ◽  
Process Analysis ◽  
Surface Ozone ◽  
Eastern China ◽  
Meteorological Conditions ◽  
Transboundary Transport ◽  
Anthropogenic Nitrogen ◽  
Central Eastern ◽  
Emission Changes

Abstract. Recent studies have shown that surface ozone (O3) concentrations over Central Eastern China (CEC) have increased significantly during the past decade. We quantified the effects of changes in meteorological conditions and O3 precursor emissions on surface O3 levels over CEC between July 2003 and July 2015 using the GEOS-Chem model. The simulated monthly mean maximum daily 8-h average O3 concentration (MDA8 O3) in July increased by approximately 13.6 %, from 65.5 ± 7.9 ppbv (2003) to 74.4 ± 8.7 ppbv (2015), comparable to the observed results. The change in meteorology led to an increase of MDA8 O3 of 5.8 ± 3.9 ppbv over the central part of CEC, in contrast to a decrease of about −0.8 ± 3.5 ppbv over the eastern part of the region. In comparison, the MDA8 O3 over the central and eastern parts of CEC increased by 3.5 ± 1.4 ppbv and 5.6 ± 1.8 ppbv due to the increased emissions. The increase in regional averaged O3 resulting from the emission increase (4.0 ± 1.9 ppbv) was higher than that caused by meteorological changes (3.1 ± 4.9 ppbv) relative to the 2003 standard simulation, while the regions with larger O3 increases showed a higher sensitivity to meteorological conditions than to emission changes. Sensitivity tests indicate that increased levels of anthropogenic non-methane volatile organic compounds (NMVOCs) dominate the O3 increase over the eastern part of CEC, and anthropogenic nitrogen oxides (NOx) mainly increase O3 concentrations over the central and western parts, while decrease O3 in a few urban areas in the eastern part. Process analysis showed that net photochemical production and meteorological conditions (transport in particular) are two important factors that influence O3 levels over the CEC. The results of this study suggest a need to further assess the effectiveness of control strategies for O3 pollution in the context of regional meteorology, transboundary transport, and anthropogenic emission changes.

scholarly journals The Role of Meteorological Conditions and Pollution Control Strategies in Reducing Air Pollution in Beijing during APEC 2014 and Parade 2015

2017 ◽  
Author(s):  
Pengfei Liang ◽  
Tong Zhu ◽  
Yanhua Fang ◽  
Yingruo Li ◽  
Yiqun Han ◽  
...  
Keyword(s):  
Air Pollution ◽  
Pollution Control ◽  
Meteorological Parameters ◽  
Control Strategies ◽  
Meteorological Conditions ◽  
Air Pollutant ◽  
Pollutant Concentrations ◽  
Air Pollutant Concentrations ◽  
Pm2.5 Concentration

Abstract. To control severe air pollution in China, comprehensive pollution control strategies have been implemented throughout the country in recent years. To evaluate the effectiveness of these strategies, the influence of meteorological conditions on levels of air pollution needs to be determined. We therefore developed a generalized linear regression model (GLM) to establish the relationship between the concentrations of air pollutants and meteorological parameters. Using the intensive air pollution control strategies implemented during the Asia-Pacific Economic Cooperation Forum in 2014 (APEC 2014) and the Victory Parade for the Commemoration of the 70th Anniversary of the Chinese Anti-Japanese War and the World Anti-Fascist War in 2015 (Parade 2015) as examples, we estimated the role of meteorological conditions and pollution control strategies in reducing air pollution levels in Beijing. During the APEC (1 October to 31 December 2014) and Parade (1 August to 31 December 2015) sampling periods, atmospheric particulate matter of aerodynamic diameter ≤ 2.5 μm (PM2.5) samples were collected and gaseous pollutants (SO2, NO, NOx, and O3) were measured online at a site in Peking University (PKU). The concentrations of all pollutants except ozone decreased dramatically (by more than 20 %) during both events, compared with the levels during non-control periods. To determine the influence of meteorological conditions on the levels of air pollution, we first compared the air pollutant concentrations during days with stable meteorological conditions (i.e. when the daily average wind speed (WS) was less than 2.50 m s−1 and planetary boundary layer (PBL) height was lower than 290 m). We found that the average PM2.5 concentration during APEC decreased by 45.7 % compared with the period before APEC and by 44.4 % compared with the period after APEC. This difference was attributed to emission reduction efforts during APEC. However, there were few days with stable meteorological conditions during Parade. As such, we were unable to estimate the level of emission reduction efforts during this period. Finally, GLMs based only on meteorological parameters were built to predict air pollutant concentrations, which could explain more than 70 % of the variation in air pollutant concentration levels, after incorporating the nonlinear relationships between certain meteorological parameters and the concentrations of air pollutants. Evaluation of the GLM performance revealed that the GLM, even based only on meteorological parameters, could be satisfactory to estimate the contribution of meteorological conditions in reducing air pollution, and hence the contribution of control strategies in reducing air pollution. Using the GLM, we found that the meteorological conditions and pollution control strategies contributed 30 % and 28 % to the reduction of the PM2.5 concentration during APEC 2014, and 38 % and 25 % during Parade 2015. We also estimated the contribution of meteorological conditions and control strategies implemented during the two events in reducing the concentrations of gaseous pollutants and PM2.5 components with the GLMs, revealing the effective control of anthropogenic emissions.

scholarly journals Difference in PM2.5 Variations between Urban and Rural Areas over Eastern China from 2001 to 2015

Atmosphere ◽  
2018 ◽  
Vol 9 (8) ◽  
pp. 312 ◽  
Author(s):  
Changqing Lin ◽  
Alexis Lau ◽  
Ying Li ◽  
Jimmy Fung ◽  
Chengcai Li ◽  
...  
Keyword(s):  
Rural Areas ◽  
Urban Areas ◽  
Eastern China ◽  
Population Exposure ◽  
Spatial Difference ◽  
The Past ◽  
The Difference ◽  
Urban And Rural Areas ◽  
Pm2.5 Concentration

To more effectively reduce population exposure to PM2.5, control efforts should target densely populated urban areas. In this study, we took advantage of satellite-derived PM2.5 data to assess the difference in PM2.5 variations between urban and rural areas over eastern China during the past three Five-Year Plan (FYP) periods (2001–2015). The results show that urban areas experienced less of a decline in PM2.5 concentration than rural areas did in more than half of the provinces during the 11th FYP period (2006–2010). In contrast, most provinces experienced a greater reduction of PM2.5 concentration in urban areas than in rural areas during the 10th and 12th FYP periods (2001–2005 and 2011–2015, respectively). During the recent 12th FYP period, the rates of decline in PM2.5 concentration in urban areas were more substantial than in rural areas by as much as 1.5 μg·m−3·year−1 in Beijing and 2.0 μg·m−3·year−1 in Tianjin. These results suggest that the spatial difference in PM2.5 change was conducive to a reduction in the population exposure to PM2.5 in most provinces during recent years.

scholarly journals The Impact of the Lockdown Caused by the COVID-19 Pandemic on the Fine Particulate Matter (PM2.5) Air Pollution: The Greek Paradigm

2021 ◽  
Vol 18 (13) ◽  
pp. 6748
Author(s):  
Ourania S. Kotsiou ◽  
Georgios K. D. Saharidis ◽  
Georgios Kalantzis ◽  
Evangelos C. Fradelos ◽  
Konstantinos I. Gourgoulianis
Keyword(s):  
Air Pollution ◽  
Wireless Sensors ◽  
Fine Particulate Matter ◽  
Meteorological Conditions ◽  
Significant Drop ◽  
Fine Particulate ◽  
Guideline Value ◽  
The Mean ◽  
The Impact ◽  
Pm2.5 Concentration

Introduction: Responding to the coronavirus pandemic, Greece implemented the largest quarantine in its history. No data exist regarding its impact on PM2.5 pollution. We aimed to assess PM2.5 levels before, during, and after lockdown (7 March 2020–16 May 2020) in Volos, one of Greece’s most polluted industrialized cities, and compare PM2.5 levels with those obtained during the same period last year. Meteorological conditions were examined as confounders. Methods: The study period was discriminated into three phases (pre-lockdown: 7 March–9 March, lockdown: 10 March–4 May, and post-lockdown period: 5 May–16 May). A wireless sensors network was used to collect PM2.5, temperature, relative humidity, rainfall, and wind speed data every 2 s. Results: The lockdown resulted in a significant drop of PM2.5 by 37.4% in 2020, compared to 2019 levels. The mean daily concentrations of PM2.5 exceeded the WHO’s guideline value for 24-h mean levels of PM2.5 35% of the study period. During the strictest lockdown (23 March to 4 May), the mean daily PM2.5 levels exceeded the standard 41% of the time. The transition from the pre-lockdown period into lockdown or post-lockdown periods was associated with lower PM2.5 concentrations. Conclusions: A reduction in the mean daily PM2.5 concentration was found compared to 2019. Lockdown was not enough to avoid severe exceedances of air pollution in Volos.

scholarly journals Separating emission and meteorological contributions to long-term PM<sub>2.5</sub> trends over eastern China during 2000–2018

2021 ◽  
Vol 21 (12) ◽  
pp. 9475-9496
Author(s):  
Qingyang Xiao ◽  
Yixuan Zheng ◽  
Guannan Geng ◽  
Cuihong Chen ◽  
Xiaomeng Huang ◽  
...  
Keyword(s):  
Machine Learning ◽  
Yangtze River ◽  
Eastern China ◽  
Yangtze River Delta ◽  
Meteorological Conditions ◽  
River Delta ◽  
The Yangtze River ◽  
The Yangtze River Delta ◽  
Meteorological Effects

Abstract. The contribution of meteorology and emissions to long-term PM2.5 trends is critical for air quality management but has not yet been fully analyzed. Here, we used the combination of a machine learning model, statistical method, and chemical transport model to quantify the meteorological impacts on PM2.5 pollution during 2000–2018. Specifically, we first developed a two-stage machine learning PM2.5 prediction model with a synthetic minority oversampling technique to improve the satellite-based PM2.5 estimates over highly polluted days, thus allowing us to better characterize the meteorological effects on haze events. Then we used two methods to examine the meteorological contribution to PM2.5: a generalized additive model (GAM) driven by the satellite-based full-coverage daily PM2.5 retrievals and the Weather Research and Forecasting/Community Multiscale Air Quality (WRF/CMAQ) modeling system. We found good agreements between GAM estimations and the CMAQ model estimations of the meteorological contribution to PM2.5 on a monthly scale (correlation coefficient between 0.53–0.72). Both methods revealed the dominant role of emission changes in the long-term trend of PM2.5 concentration in China during 2000–2018, with notable influence from the meteorological condition. The interannual variabilities in meteorology-associated PM2.5 were dominated by the fall and winter meteorological conditions, when regional stagnant and stable conditions were more likely to happen and when haze events frequently occurred. From 2000 to 2018, the meteorological contribution became more unfavorable to PM2.5 pollution across the North China Plain and central China but were more beneficial to pollution control across the southern part, e.g., the Yangtze River Delta. The meteorology-adjusted PM2.5 over eastern China (denoted East China in figures) peaked in 2006 and 2011, mainly driven by the emission peaks in primary PM2.5 and gas precursors in these years. Although emissions dominated the long-term PM2.5 trends, the meteorology-driven anomalies also contributed −3.9 % to 2.8 % of the annual mean PM2.5 concentrations in eastern China estimated from the GAM. The meteorological contributions were even higher regionally, e.g., −6.3 % to 4.9 % of the annual mean PM2.5 concentrations in the Beijing-Tianjin-Hebei region, −5.1 % to 4.3 % in the Fenwei Plain, −4.8 % to 4.3 % in the Yangtze River Delta, and −25.6 % to 12.3 % in the Pearl River Delta. Considering the remarkable meteorological effects on PM2.5 and the possible worsening trend of meteorological conditions in the northern part of China where air pollution is severe and population is clustered, stricter clean air actions are needed to avoid haze events in the future.

scholarly journals Multi-dimensional satellite observations of aerosol properties and aerosol types over three major urban clusters in eastern China

2021 ◽  
Author(s):  
Yuqin Liu ◽  
Tao Lin ◽  
Juan Hong ◽  
Yonghong Wang ◽  
Lamei Shi ◽  
...  
Keyword(s):  
Vertical Distribution ◽  
Eastern China ◽  
Peak Frequency ◽  
Meteorological Conditions ◽  
River Delta ◽  
Smoke Aerosol ◽  
The Yrd ◽  
The Vertical Distribution ◽  
Aerosol Types ◽  
Aerosol Properties

Abstract. Using nine years (2007–2015) of data from passive (MODIS/Aqua) and active (CALIOP/CALIPSO) satellite measurements over China, we investigate (1) the temporal and spatial variation of aerosol properties over the Beijing-Tianjin-Hebei (BTH) region, the Yangtze River Delta (YRD) and the Pearl River Delta (PRD) and (2) the vertical distribution of aerosol types and extinction coefficients for different aerosol optical depth (AOD) and meteorological conditions. The results show the different spatial patterns and seasonal variations of the AOD over the three regions. Annual time series reveal the occurrence of AOD maxima in 2011 over the YRD and in 2012 over the BTH and PRD; thereafter the AOD decreases steadily. Using the CALIOP vertical feature mask, the contributions of different aerosol types to the AOD were analysed: contributions of dust and polluted dust decrease from north to south, contributions of clean ocean, polluted continental, clean continental and smoke aerosol increase from south to north. In the vertical, the peak frequency of occurrence (FO) for each aerosol type depends on region and season and varies with AOD and meteorological conditions. In general, three distinct layers are observed with the peak FO at the surface (clean continental and clean marine aerosol), at ~1 km (polluted dust and polluted continental aerosol) and at ~3 km (smoke aerosol), whereas dust aerosol may occur all over the altitude range considered in this study (from the surface up to 8 km). In this study nighttime CALIOP profiles were used. The comparison with daytime profiles shows substantial differences in the FO profiles with altitude which suggest effects of boundary layer dynamics and aerosol transport on the vertical distribution of aerosol types.

scholarly journals Impact of modified turbulent diffusion of PM<sub>2.5</sub> aerosol in WRF-Chem simulations in Eastern China

2021 ◽  
Author(s):  
Wenxing Jia ◽  
Xiaoye Zhang
Keyword(s):  
Diffusion Process ◽  
Turbulent Diffusion ◽  
Turbulent Transport ◽  
Eastern China ◽  
Mixing Process ◽  
Heavy Pollution ◽  
Mixing Length Theory ◽  
Relationship Of ◽  
Pm2.5 Concentration

Abstract. Correct description of the boundary layer mixing process of particle is an important prerequisite to understanding the mechanism of heavy pollution episodes. Turbulent mixing process of particles is usually denoted by the turbulent diffusion relationship of heat, meaning that the turbulent transport of particles and heat are similar. This similarity has, however, never been verified. Here we investigate the dissimilarity between particles and heat, indicating that the unified treatment of all scalars in the model is questionable. Using mixing-length theory, the turbulent diffusion relationship of particle is established, embedded in the model and verified on a long-term scale. Simulated results of PM2.5 concentration were improved by 8.3 % (2013), 17 % (2014), 11 % (2015) and 11.7 % (2017) in Eastern China, respectively. However, under the influence of complex topography, the turbulent diffusion process is insensitive to the simulation of the pollutant concentration. In addition to the PM2.5 concentration, the simulation of the CO concentration has also been improved, which shows that the turbulent diffusion process is extremely critical to the change in the concentration of pollutants.

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