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Hong Liao - One of the best experts on this subject based on the ideXlab platform.
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Impact of western Pacific subtropical high on Ozone Pollution over eastern China
Atmospheric Chemistry and Physics, 2021Co-Authors: Zhongjing Jiang, Lin Zhang, Cheng Gong, Hong LiaoAbstract:Abstract. Surface Ozone is a major pollutant in eastern China, especially during the summer season. The formation of surface Ozone Pollution highly depends on meteorological conditions largely controlled by regional circulation patterns which can modulate Ozone concentrations by influencing the emission of the precursors, the chemical production rates, and regional transport. Here we show that summertime Ozone Pollution over eastern China is distinctly modulated by the variability of the western Pacific subtropical high (WPSH), a major synoptic system that controls the summertime weather conditions of East Asia. Composite and regression analyses indicate that a positive WPSH anomaly is associated with higher than normal surface Ozone concentration over northern China but lower Ozone over southern China. Stronger than normal WPSH leads to higher temperatures, stronger solar radiation at the land surface, lower relative humidity, and less precipitation in northern China, favoring the production and accumulation of surface Ozone. In contrast, all meteorological variables show reverse changes in southern China under a stronger WPSH. GEOS-Chem simulations reasonably reproduce the observed Ozone changes associated with the WPSH and support the statistical analyses. We further conduct a budget diagnosis to quantify the detailed contributions of chemistry, transport, mixing, and convection processes. The result shows that chemistry plays a decisive role in leading the Ozone changes among these processes. Results show that the changes in Ozone are primarily attributed to chemical processes. Moreover, the natural emission of precursors from biogenic and soil sources, a major component influencing the chemical production, accounts for ∼ 30 % of the total surface Ozone changes.
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Impact of Western Pacific Subtropical High on Ozone Pollution over Eastern China
2020Co-Authors: Zhongjing Jiang, Lin Zhang, Cheng Gong, Hong LiaoAbstract:Abstract. Surface Ozone is a major pollutant in Eastern China, especially during the summer season. The formation of surface Ozone Pollution highly depends on meteorological conditions as generally controlled regional circulation patterns. Here we show that summertime Ozone Pollution over Eastern China is distinctly modulated by the variability of West Pacific Subtropical High (WPSH), a major synoptic system that controls the summertime weather conditions of East Asia. Composite and regression analyses indicate that positive WPSH anomaly is associated with higher than normal surface Ozone concentration over Northern China but lower Ozone over Southern China. We show that this is mainly driven by changes in meteorological variables with stronger than normal WPSH leading to higher temperatures, stronger solar radiation at the land surface, lower relative humidity, and less precipitation in Northern China, favoring the production and accumulation of surface Ozone. In contrast, all variables show reverse changes in Southern China under stronger WPSH. GEOS-Chem simulations reasonably reproduce the observed Ozone changes associated with the WPSH and support the statistical analyses. Detailed contributions of different processes are quantified through budget diagnosis, which emphasizes the decisive role of chemistry. Natural emission of precursors from biogenic and soil sources accounts for ~30 % of the total surface Ozone changes.
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The impact of synoptic patterns on summertime Ozone Pollution in the North China Plain.
The Science of the total environment, 2020Co-Authors: Yueming Dong, Jianping Guo, Zhongjing Jiang, Yiqi Chu, Liang Chang, Yang Yang, Hong LiaoAbstract:Abstract Surface Ozone Pollution is a challenging environmental issue in most parts of China. In particular, the North China Plain (NCP) region suffers from the severest Ozone Pollution throughout the country. In addition to the emission of precursors, Ozone concentration is closely related to meteorological conditions resulting from regional atmospheric circulation. In this study, we investigate the relationship between synoptic patterns and summertime Ozone Pollution in the NCP using the objective principal component analysis in T-mode (T-PCA) classification method. Four dominant synoptic patterns are identified during the summers of 2014–2018. The heaviest Ozone Pollution is found to be associated with a high pressure anomaly over the Northwest Pacific and a distinct low pressure center in Northeast China. The southwesterly wind surrounding the low pressure center brings dry, warm air from inland South China, resulting in a high temperature, low humidity environment in the NCP, which favors the chemical formation of surface Ozone. Locally, this type is associated with a moderate planetary boundary layer height (PBLH) of ~860 m and a stronger warm anomaly within the boundary layer than the upper level. We also notice a non-linear relationship between surface Ozone concentration and the PBLH, i.e., Ozone concentration first increases with PBLH till ~0.9 km, and then remains stable. This initial increase may relate to enhanced mixing with upper levels where Ozone concentration is typically higher than that near the surface. However, when PBLH further increases, this downward mixing effect is balanced with the stronger upward turbulent mixing so that surface Ozone shows little change. The synoptic patterns identified here, however, is unlikely responsible for the observed increasing trend in Ozone concentration over the NCP region. Our study sheds light on the meteorological contribution to surface Ozone Pollution in North China and provides a reference for the Pollution control and prediction.
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an evaluation of the ability of the Ozone monitoring instrument omi to observe boundary layer Ozone Pollution across china application to 2005 2017 Ozone trends
Atmospheric Chemistry and Physics, 2019Co-Authors: Lu Shen, Guanyu Huang, Hong Liao, Daniel J Jacob, Ke Li, Tao WangAbstract:Abstract. Nadir-viewing satellite observations of tropospheric Ozone in the UV have been shown to have some sensitivity to boundary layer Ozone Pollution episodes, but so far they have not yet been compared to surface Ozone observations collected by large-scale monitoring networks. Here we use 2013–2017 surface Ozone data from China's new Ministry of Ecology and Environment (MEE) network of ∼ 1000 sites, together with vertical profiles from Ozonesondes and aircraft, to quantify the ability of tropospheric Ozone retrievals from the Ozone Monitoring Instrument (OMI) and to detect boundary layer Ozone Pollution in China. We focus on summer when Ozone Pollution in China is most severe and when OMI has the strongest sensitivity. After subtracting the Pacific background, we find that the 2013–2017 mean OMI Ozone enhancements over eastern China have strong spatial correlation with the corresponding multiyear means in the surface afternoon observations ( R=0.73 ), and that OMI can estimate these multiyear means in summer afternoon surface Ozone with a precision of 8 ppb. The OMI data show significantly higher values on observed surface Ozone episode days ( >82 ppb) than on non-episode days. Day-to-day correlations with surface Ozone are much weaker due to OMI noise and are stronger for sites in southern China ( 34 ∘ N; R=0.3 –0.6) than in northern China ( R=0.1 –0.3) because of weaker retrieval sensitivity and larger upper tropospheric variability in the north. Ozonesonde data show that much of the variability of OMI Ozone over southern China in summer is driven by the boundary layer. Comparison of 2005–2009 and 2013–2017 OMI data indicates that mean summer afternoon surface Ozone in southern China (including urban and rural regions) has increased by 3.5±3.0 ppb over the 8-year period and that the number of episode days per summer has increased by 2.2±0.4 (as diagnosed by an extreme value model), generally consistent with the few long-term surface records. Ozone increases have been particularly large in the Yangtze River Delta and in the Hubei, Guangxi and Hainan provinces.
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spatial distribution and temporal trend of Ozone Pollution inchina observed with the omi satellite instrument 2005 2017
Atmospheric Chemistry and Physics, 2018Co-Authors: Lu Shen, Guanyu Huang, Daniel J Jacob, Ke Li, Hong LiaoAbstract:Abstract. We use data from the new China Ministry of Ecology and Environment (MEE) network to show that OMI satellite observations of tropospheric Ozone can successfully map the distribution of surface Ozone Pollution in China and the frequency of high-Ozone episodes. After subtracting the Pacific background, OMI Ozone enhancements over China can quantify mean summer afternoon surface Ozone with a precision of 10.7 ppb and a spatial correlation coefficient R =0.73. Day-to-day correlations between OMI and the MEE Ozone data are statistically significant but limited by noise in the individual OMI retrievals. OMI shows significantly higher values on surface Ozone episode days (>82 ppb). An extreme value model can successfully predict the probability of surface Ozone episodes from the daily OMI data. The 2005–2017 OMI record shows a 0.67 ppb a −1 increase in mean summer afternoon Ozone in eastern China and an increasing frequency of Ozone Pollution episodes particularly in the north.
Lin Zhang - One of the best experts on this subject based on the ideXlab platform.
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Impact of western Pacific subtropical high on Ozone Pollution over eastern China
Atmospheric Chemistry and Physics, 2021Co-Authors: Zhongjing Jiang, Lin Zhang, Cheng Gong, Hong LiaoAbstract:Abstract. Surface Ozone is a major pollutant in eastern China, especially during the summer season. The formation of surface Ozone Pollution highly depends on meteorological conditions largely controlled by regional circulation patterns which can modulate Ozone concentrations by influencing the emission of the precursors, the chemical production rates, and regional transport. Here we show that summertime Ozone Pollution over eastern China is distinctly modulated by the variability of the western Pacific subtropical high (WPSH), a major synoptic system that controls the summertime weather conditions of East Asia. Composite and regression analyses indicate that a positive WPSH anomaly is associated with higher than normal surface Ozone concentration over northern China but lower Ozone over southern China. Stronger than normal WPSH leads to higher temperatures, stronger solar radiation at the land surface, lower relative humidity, and less precipitation in northern China, favoring the production and accumulation of surface Ozone. In contrast, all meteorological variables show reverse changes in southern China under a stronger WPSH. GEOS-Chem simulations reasonably reproduce the observed Ozone changes associated with the WPSH and support the statistical analyses. We further conduct a budget diagnosis to quantify the detailed contributions of chemistry, transport, mixing, and convection processes. The result shows that chemistry plays a decisive role in leading the Ozone changes among these processes. Results show that the changes in Ozone are primarily attributed to chemical processes. Moreover, the natural emission of precursors from biogenic and soil sources, a major component influencing the chemical production, accounts for ∼ 30 % of the total surface Ozone changes.
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Impact of Western Pacific Subtropical High on Ozone Pollution over Eastern China
2020Co-Authors: Zhongjing Jiang, Lin Zhang, Cheng Gong, Hong LiaoAbstract:Abstract. Surface Ozone is a major pollutant in Eastern China, especially during the summer season. The formation of surface Ozone Pollution highly depends on meteorological conditions as generally controlled regional circulation patterns. Here we show that summertime Ozone Pollution over Eastern China is distinctly modulated by the variability of West Pacific Subtropical High (WPSH), a major synoptic system that controls the summertime weather conditions of East Asia. Composite and regression analyses indicate that positive WPSH anomaly is associated with higher than normal surface Ozone concentration over Northern China but lower Ozone over Southern China. We show that this is mainly driven by changes in meteorological variables with stronger than normal WPSH leading to higher temperatures, stronger solar radiation at the land surface, lower relative humidity, and less precipitation in Northern China, favoring the production and accumulation of surface Ozone. In contrast, all variables show reverse changes in Southern China under stronger WPSH. GEOS-Chem simulations reasonably reproduce the observed Ozone changes associated with the WPSH and support the statistical analyses. Detailed contributions of different processes are quantified through budget diagnosis, which emphasizes the decisive role of chemistry. Natural emission of precursors from biogenic and soil sources accounts for ~30 % of the total surface Ozone changes.
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severe surface Ozone Pollution in china a global perspective
Environmental Science and Technology Letters, 2018Co-Authors: Jiayun Hong, Tao Wang, Lin Zhang, O R Cooper, Martin G Schultz, Meng Gao, Yuanhong Zhao, Yuanhang ZhangAbstract:The nationwide extent of surface Ozone Pollution in China and its comparison to the global Ozone distribution have not been recognized because of the scarcity of Chinese monitoring sites before 2012. Here we address this issue by using the latest 5 year (2013–2017) surface Ozone measurements from the Chinese monitoring network, combined with the recent Tropospheric Ozone Assessment Report (TOAR) database for other industrialized regions such as Japan, South Korea, Europe, and the United States (JKEU). We use various human health and vegetation exposure metrics. We find that although the median Ozone values are comparable between Chinese and JKEU cities, the magnitude and frequency of high-Ozone events are much larger in China. The national warm-season (April–September) fourth highest daily maximum 8 h average (4MDA8) Ozone level (86.0 ppb) and the number of days with MDA8 values of >70 ppb (NDGT70, 29.7 days) in China are 6.3–30% (range of regional mean differences) and 93–575% higher, respectively, than ...
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Intercontinental source attribution of Ozone Pollution at western U.S. sites using an adjoint method
Geophysical Research Letters, 2009Co-Authors: Lin Zhang, Daniel J Jacob, Monika Kopacz, Daven K. Henze, Kumaresh Singh, Daniel A. JaffeAbstract:[1] We use the GEOS-Chem chemical transport model and its adjoint to quantify source contributions to Ozone Pollution at two adjacent sites on the U.S. west coast in spring 2006: Mt. Bachelor Observatory (MBO) at 2.7 km altitude and Trinidad Head (TH) at sea level. The adjoint computes the sensitivity of Ozone concentrations at the receptor sites to Ozone production rates at 2° x 2.5° resolution over the history of air parcels reaching the site. MBO experiences distinct Asian Ozone Pollution episodes; most of the Ozone production in these episodes takes place over East Asia with maxima over northeast China and southern Japan, adding to a diffuse background production distributed over the extratropical northern hemisphere. TH shows the same Asian origins for Ozone as MBO but no distinct Asian Pollution episodes. We find that transpacific Pollution plumes transported in the free troposphere are diluted by a factor of 3 when entrained into the boundary layer, explaining why these plumes are undetectable in U.S. surface air.
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transpacific transport of Ozone Pollution and the effect of recent asian emission increases on air quality in north america an integrated analysis using satellite aircraft Ozonesonde and surface observations
Atmospheric Chemistry and Physics, 2008Co-Authors: Lin Zhang, Daniel J Jacob, Daniel A. Jaffe, Anne M. Thompson, K F Boersma, J R Olson, Kevin W Bowman, J Worden, Melody A AveryAbstract:We use an ensemble of aircraft, satellite, sonde, and surface observations for April–May 2006 (NASA/INTEX-B aircraft campaign) to better understand the mechanisms for transpacific Ozone Pollution and its implications for North American air quality. The observations are interpreted with a global 3-D chemical transport model (GEOS-Chem). OMI NO 2 satellite observations constrain Asian anthropogenic NO x emissions and indicate a factor of 2 increase from 2000 to 2006 in China. Satellite observations of CO from AIRS and TES indicate two major events of Asian transpacific Pollution during INTEX-B. Correlation between TES CO and Ozone observations shows evidence for transpacific Ozone Pollution. The semi-permanent Pacific High and Aleutian Low cause splitting of transpacific Pollution plumes over the Northeast Pacific. The northern branch circulates around the Aleutian Low and has little impact on North America. The southern branch circulates around the Pacific High and some of that air impacts western North America. Both aircraft measurements and model results show sustained Ozone production driven by peroxyacetylnitrate (PAN) decomposition in the southern branch, roughly doubling the transpacific influence from Ozone produced in the Asian boundary layer. Model simulation of Ozone observations at Mt. Bachelor Observatory in Oregon (2.7 km altitude) indicates a mean Asian Ozone Pollution contribution of 9±3 ppbv to the mean observed concentration of 54 ppbv, reflecting mostly an enhancement in background Ozone rather than episodic Asian plumes. Asian Pollution enhanced surface Ozone concentrations by 5–7 ppbv over western North America in spring 2006. The 2000–2006 rise in Asian anthropogenic emissions increased this influence by 1–2 ppbv.
Zhongjing Jiang - One of the best experts on this subject based on the ideXlab platform.
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Impact of western Pacific subtropical high on Ozone Pollution over eastern China
Atmospheric Chemistry and Physics, 2021Co-Authors: Zhongjing Jiang, Lin Zhang, Cheng Gong, Hong LiaoAbstract:Abstract. Surface Ozone is a major pollutant in eastern China, especially during the summer season. The formation of surface Ozone Pollution highly depends on meteorological conditions largely controlled by regional circulation patterns which can modulate Ozone concentrations by influencing the emission of the precursors, the chemical production rates, and regional transport. Here we show that summertime Ozone Pollution over eastern China is distinctly modulated by the variability of the western Pacific subtropical high (WPSH), a major synoptic system that controls the summertime weather conditions of East Asia. Composite and regression analyses indicate that a positive WPSH anomaly is associated with higher than normal surface Ozone concentration over northern China but lower Ozone over southern China. Stronger than normal WPSH leads to higher temperatures, stronger solar radiation at the land surface, lower relative humidity, and less precipitation in northern China, favoring the production and accumulation of surface Ozone. In contrast, all meteorological variables show reverse changes in southern China under a stronger WPSH. GEOS-Chem simulations reasonably reproduce the observed Ozone changes associated with the WPSH and support the statistical analyses. We further conduct a budget diagnosis to quantify the detailed contributions of chemistry, transport, mixing, and convection processes. The result shows that chemistry plays a decisive role in leading the Ozone changes among these processes. Results show that the changes in Ozone are primarily attributed to chemical processes. Moreover, the natural emission of precursors from biogenic and soil sources, a major component influencing the chemical production, accounts for ∼ 30 % of the total surface Ozone changes.
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Impact of Western Pacific Subtropical High on Ozone Pollution over Eastern China
2020Co-Authors: Zhongjing Jiang, Lin Zhang, Cheng Gong, Hong LiaoAbstract:Abstract. Surface Ozone is a major pollutant in Eastern China, especially during the summer season. The formation of surface Ozone Pollution highly depends on meteorological conditions as generally controlled regional circulation patterns. Here we show that summertime Ozone Pollution over Eastern China is distinctly modulated by the variability of West Pacific Subtropical High (WPSH), a major synoptic system that controls the summertime weather conditions of East Asia. Composite and regression analyses indicate that positive WPSH anomaly is associated with higher than normal surface Ozone concentration over Northern China but lower Ozone over Southern China. We show that this is mainly driven by changes in meteorological variables with stronger than normal WPSH leading to higher temperatures, stronger solar radiation at the land surface, lower relative humidity, and less precipitation in Northern China, favoring the production and accumulation of surface Ozone. In contrast, all variables show reverse changes in Southern China under stronger WPSH. GEOS-Chem simulations reasonably reproduce the observed Ozone changes associated with the WPSH and support the statistical analyses. Detailed contributions of different processes are quantified through budget diagnosis, which emphasizes the decisive role of chemistry. Natural emission of precursors from biogenic and soil sources accounts for ~30 % of the total surface Ozone changes.
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The impact of synoptic patterns on summertime Ozone Pollution in the North China Plain.
The Science of the total environment, 2020Co-Authors: Yueming Dong, Jianping Guo, Zhongjing Jiang, Yiqi Chu, Liang Chang, Yang Yang, Hong LiaoAbstract:Abstract Surface Ozone Pollution is a challenging environmental issue in most parts of China. In particular, the North China Plain (NCP) region suffers from the severest Ozone Pollution throughout the country. In addition to the emission of precursors, Ozone concentration is closely related to meteorological conditions resulting from regional atmospheric circulation. In this study, we investigate the relationship between synoptic patterns and summertime Ozone Pollution in the NCP using the objective principal component analysis in T-mode (T-PCA) classification method. Four dominant synoptic patterns are identified during the summers of 2014–2018. The heaviest Ozone Pollution is found to be associated with a high pressure anomaly over the Northwest Pacific and a distinct low pressure center in Northeast China. The southwesterly wind surrounding the low pressure center brings dry, warm air from inland South China, resulting in a high temperature, low humidity environment in the NCP, which favors the chemical formation of surface Ozone. Locally, this type is associated with a moderate planetary boundary layer height (PBLH) of ~860 m and a stronger warm anomaly within the boundary layer than the upper level. We also notice a non-linear relationship between surface Ozone concentration and the PBLH, i.e., Ozone concentration first increases with PBLH till ~0.9 km, and then remains stable. This initial increase may relate to enhanced mixing with upper levels where Ozone concentration is typically higher than that near the surface. However, when PBLH further increases, this downward mixing effect is balanced with the stronger upward turbulent mixing so that surface Ozone shows little change. The synoptic patterns identified here, however, is unlikely responsible for the observed increasing trend in Ozone concentration over the NCP region. Our study sheds light on the meteorological contribution to surface Ozone Pollution in North China and provides a reference for the Pollution control and prediction.
Aijun Ding - One of the best experts on this subject based on the ideXlab platform.
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Understanding Ozone Pollution in the Yangtze River Delta of eastern China from the perspective of diurnal cycles
The Science of the total environment, 2020Co-Authors: Xin Huang, Nan Wang, Aijun DingAbstract:Abstract Ozone (O3) Pollution has aroused increasing attention in China in past years, especially in the Yangtze River Delta (YRD), eastern China. Ozone and its precursors generally feature different diurnal patterns, which is closely related to atmospheric physical and chemical processes. This work aims to shed more light on the causes of Ozone Pollution from the perspective of the diurnal patterns. Hundreds of Ozone Pollution days (with maximum hourly O3 concentration over 100 ppb) during 2013–2017 were identified and then clustered into 4 typical types according to the diurnal variation patterns. We found that Ozone Pollution in Shanghai was particularly severe when anthropogenic pollutant mixed with biogenic volatile organic compounds (BVOCs) under the prevailing southwesterly wind in summer. The reason could be attributed to the spatial disparities of Ozone sensitivity regime in YRD: VOC-limited regime around in the urban area and NOx-limited regime in the rural forest regions in the southern and southwest. The transition of sensitivity regimes along south/southwest wind tended to promote the photochemical production of Ozone, making daily O3 Pollution time exceeding 6 h of the day. In addition, Ozone peak concentration in Shanghai was highly dependent on the evolution of sea-land breezes (SLBs). Earlier sea breeze associated with approaching typhoon in the West Pacific caused less cloud (−25%) and more solar radiation (11%) in YRD, which subsequently led to a rapid increase of O3 concentration in the morning and a deteriorated Ozone Pollution during noon and the afternoon. This study highlights the importance of observation-based processes understanding in air quality studies.
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The impacts of surface Ozone Pollution on winter wheat productivity in China--An econometric approach.
Environmental pollution (Barking Essex : 1987), 2015Co-Authors: Fei Jiang, Funing Zhong, Xun Zhou, Aijun DingAbstract:The impact of surface Ozone Pollution on winter wheat yield is empirically estimated by considering socio-economic and weather determinants. This research is the first to use an economic framework to estimate the Ozone impact, and a unique county-level panel is employed to examine the impact of the increasing surface Ozone concentration on the productivity of winter wheat in China. In general, the increment of surface Ozone concentration during the Ozone-sensitive period of winter wheat is determined to be harmful to its yield, and a conservative reduction of Ozone Pollution could significantly increase China's wheat supply.
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Impacts of Surface Ozone Pollution on Crop Productivity: Evidence from Winter Wheat in China
2015Co-Authors: Fei Jiang, Funing Zhong, Aijun Ding, Xun ZhouAbstract:The impact of surface Ozone Pollution on the yield of winter wheat is empirically estimated by considering socio-economic and climatic determinants. This research is the first to use an economic framework to estimate the Ozone impact, and a unique county-level panel is employed to examine the impact of the increase of surface Ozone concentration on the productivity of winter wheat. In general, the increment of surface Ozone concentration during the Ozone-sensitive period of winter wheat is found harmful to its yield, and the damage to China’s grain supply and economic values are non-negligible. This study also confirms that other stress conditions, such as drought and air particles, can potentially mitigate the adverse effect of surface Ozone exposure on the yield of winter wheat.
Zhicong Yin - One of the best experts on this subject based on the ideXlab platform.
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Future atmospheric circulations benefit Ozone Pollution control in Beijing-Tianjin-Hebei with global warming.
The Science of the total environment, 2020Co-Authors: Bufan Cao, Zhicong YinAbstract:Abstract Surface Ozone Pollution has become increasingly serious in recent years. Ozone Pollution will damage human health and reducing social productivity in China. Basing on an Ozone weather index (OWI) that captured the effects of climate on the ground-level Ozone, large ensemble simulations by the Community Earth System Model were introduced to project future impacts of atmospheric circulation on Ozone Pollution in Beijing-Tianjin-Hebei in late-21st century. In the future, atmospheric circulations will favour the control of Ozone Pollution in Beijing-Tianjin-Hebei region. The OWI decreased overall during the 21st century, which was nearly ignored by other studies on Ozone projections. The OWI decrease was mainly due to the increase in regional precipitation and partly due to the changes of wind and the temperature difference between 200 hPa and lower-troposphere. The increased total precipitation in the 21st century, mainly due to the increase in convectional precipitation, weakened the production of surface Ozone by its shading effect (related to more cloud cover) and wet deposition impact. During 2061–2100, the South Asia High will move southward, and the west Pacific subtropical high will shift eastward; thus, the convergence of water vapour will mainly occur in South China. Consequently, the large-scale precipitation will decrease over northern China. However, because of climate warming, the increase in specific humidity in Beijing-Tianjin-Hebei region (BTH) will enhance convectional precipitation, which will be more than 4 times the decrease in large-scale precipitation.
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Dominant Patterns of Summer Ozone Pollution in Eastern China and Associated Atmospheric Circulations
Atmospheric Chemistry and Physics, 2019Co-Authors: Zhicong Yin, Bufan Cao, Huijun WangAbstract:Abstract. Surface Ozone has been severe during summers in the eastern parts of China, damaging human health and flora and fauna. During 2015–2018, ground-level Ozone Pollution increased and intensified from south to north. In North China and the Huanghuai region, the O3 concentrations were highest. Two dominant patterns of summer Ozone Pollution were determined, i.e., a south–north covariant pattern and a south–north differential pattern. The anomalous atmospheric circulations composited for the first pattern manifested as a zonally enhanced East Asian deep trough and as a western Pacific subtropical high, whose western ridge point shifted northward. The local hot, dry air and intense solar radiation enhanced the photochemical reactions to elevate the O3 Pollution levels in North China and the Huanghuai region; however, the removal of pollutants was decreased. For the second pattern, the broad positive geopotential height anomalies at high latitudes significantly weakened cold air advection from the north, and those extending to North China resulted in locally high temperatures near the surface. In a different manner, the western Pacific subtropical high transported sufficient water vapor to the Yangtze River Delta and resulted in a locally adverse environment for the formation of surface Ozone. In addition, the most dominant pattern in 2017 and 2018 was different from that in previous years, which is investigated as a new feature.
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Dominant Patterns of Summer Ozone Pollution in Eastern China and Associated Atmospheric Circulations
2019Co-Authors: Zhicong Yin, Bufan Cao, Huijun WangAbstract:Abstract. Surface Ozone, a man-made air pollutant, has been severe during summers in the eastern parts of China, damaging human’s health and flora and fauna. During 2015–2018, ground-level Ozone Pollution increased year by year and intensified from south to north. In North China and Huanghuai region, the O3 concentrations were highest. Two dominant patterns of summer Ozone Pollution were determined, i.e., a south-north covariant pattern and a south-north differential pattern. The anomalous atmospheric circulations composited for the first pattern manifested as a zonally enhanced East Asia deep trough and as a west Pacific subtropical high whose western ridge point shifted northward. The local hot, dry air and intense solar radiation enhanced the photochemical reactions to elevate the O3 Pollution levels in North China and Huanghuai region. For the second pattern, the broad positive geopotential height anomalies at high latitudes significantly weakened cold air activity, and those extending to North China resulted in locally high temperature near the surface. In a different manner, the west Pacific subtropical high transported sufficient water vapor to the Yangtze River Delta and resulted in locally adverse environment for the formation of surface Ozone. Furthermore, the implications for the interannual differences in summer O3 Pollution have also proven to be meaningful.
