High-resolution modeling approach is increasingly being considered as a necessary step for improving the monitoring and predictions of regional air quality. This is especially true for highly urbanized region with com...High-resolution modeling approach is increasingly being considered as a necessary step for improving the monitoring and predictions of regional air quality. This is especially true for highly urbanized region with complex terrain and land-use. This study uses Community Multiscale Air Quality （CMAQ） model coupled with MM5 mesoscale model for a comprehensive analysis to assess the suitability of such high-resolution modeling system in predicting ozone air quality in the complex terrains of Osaka, Japan. The 1-km and 3-kin grid domains were nested inside a 9-km domain and the domain with 1-km grid covered the Osaka region. High-resolution Grid Point Value-Mesoscale Model （GPV-MSM） data were used after suitable validation. The simulated ozone concentrations were validated and evaluated using statistical metrics using performance criteria set for ozone. Daily maxima of ozone were found better simulated by the 1-krn grid domain than the coarser 9-km and 3-km domains, with the maximum improvement in the mean absolute gross error about 3 ppbv. In addition, 1-km grid results fared better than other grids at most of the observation stations that showed noticeable differences in gross error as well as correlation. These results amply justify the use of the integrated high-resolution MM5-CMAQ modeling system in the highly urbanized region, such as the Osaka region, which has complex terrain and land-use.展开更多
Energy consumption is a major cause of air pollution in Beijing,and the adjustment of the energy structure is of strategic importance to the reduction of carbon intensity and the improvement of air quality.In this pap...Energy consumption is a major cause of air pollution in Beijing,and the adjustment of the energy structure is of strategic importance to the reduction of carbon intensity and the improvement of air quality.In this paper,we explored the future trend of energy structure adjustment in Beijing till 2020,designed five energy scenarios focusing on the fuel substitution in power plants and heating sectors,established emission inventories,and utilized the Mesoscale Modeling System Generation 5(MM5)and the Models-3/Community Multiscale Air Quality Model(CMAQ)to evaluate the impact of these measures on air quality.By implementing this systematic energy structure adjustment,the emissions of PM_(10),PM_(2.5),SO_(2),NO_(x),and non-methane volatile organic compounds(NMVOCs)will decrease distinctly by 34.0%,53.2%,78.3%,47.0%,and 30.6%respectively in the most coalintensive scenario of 2020 compared with 2005.Correspondingly,MM5-Models-3/CMAQ simulations indicate significant reduction in the concentrations of major pollutants,implying that energy structure adjustment can play an important role in improving Beijing’s air quality.By fuel substitution for power plants and heating boilers,PM_(10),PM_(2.5),SO_(2),NO_(x),and NMVOCs will be reduced further,but slightly by 1.7%,4.5%,11.4%,13.5%,and 8.8%respectively in the least coal-intensive scenario.The air quality impacts of different scenarios in 2020 resemble each other,indicating that the potential of air quality improvement due to structure adjustment in power plants and heating sectors is limited.However,the CO_(2) emission is 10.0%lower in the least coal-intensive scenario than in the most coal-intensive one,contributing to Beijing’s ambition to build a low carbon city.Except for energy structure adjustment,it is necessary to take further measures to ensure the attainment of air quality standards.展开更多
Historical haze episodes（2013–16） in Guangzhou were examined and classified according to synoptic weather systems.Four types of weather systems were found to be unfavorable, among which ＂foreside of a cold front＂...Historical haze episodes（2013–16） in Guangzhou were examined and classified according to synoptic weather systems.Four types of weather systems were found to be unfavorable, among which ＂foreside of a cold front＂（FC） and ＂sea high pressure＂（SP） were the most frequent（〉 75% of the total）. Targeted case studies were conducted based on an FC-affected event and an SP-affected event with the aim of understanding the characteristics of the contributions of source regions to fine particulate matter（PM（2.5）） in Guangzhou. Four kinds of contributions—namely, emissions outside Guangdong Province（super-region）, emissions from the Pearl River Delta region（PRD region）, emissions from Guangzhou–Foshan–Shenzhen（GFS region）, and emissions from Guangzhou（local）—were investigated using the Weather Research and Forecasting–Community Multiscale Air Quality model. The results showed that the source region contribution differed with different weather systems. SP was a stagnant weather condition, and the source region contribution ratio showed that the local region was a major contributor（37%）, while the PRD region, GFS region and the super-region only contributed 8%, 2.8% and 7%, respectively, to PM（2.5） concentrations. By contrast, FC favored regional transport. The super-region became noticeable,contributing 34.8%, while the local region decreased to 12%. A simple method was proposed to quantify the relative impact of meteorology and emissions. Meteorology had a 35% impact, compared with an impact of-18% for emissions, when comparing the FC-affected event with that of the SP. The results from this study can provide guidance to policymakers for the implementation of effective control strategies.展开更多
As an exercise in model sensitivity, the Models-3 Community Multiscale Air Quality (CMAQ) modeling system with meteorological fields from the Regional Atmospheric Modeling System (RAMS) was applied to study the respon...As an exercise in model sensitivity, the Models-3 Community Multiscale Air Quality (CMAQ) modeling system with meteorological fields from the Regional Atmospheric Modeling System (RAMS) was applied to study the response of photochemical oxidants to systematic increases in anthropogenic volatile organic compounds (VOC) and nitrogen oxides (NO x) emissions in January 1997 over East Asia. Three simulations-one base case and two sensitivity simulations were carried out. Two sensitivity simulations were performed by assuming a 35% separate increase in anthropogenic VOC and NO x emissions comparing with the base case. Biogenic VOC emissions were held constant across the sensitivity simulations. To evaluate the model performance, ozone mixing ratios (O 3) from the base case simulation were compared with surface observations at five remote sites in Japan, and it was found that the model reproduces most of the important features in the observations. Monthly average O 3 concentrations in the daytime were examined to gain an understanding of how the increase in anthropogenic emissions affected the overall chemical system for each sensitivity simulation.展开更多
Aerosol ammonium(NH_(4)^(+)),mainly produced from the reactions of ammonia(NH_(3))with acids in the atmosphere,has significant impacts on air pollution,radiative forcing,and human health.Understanding the source and f...Aerosol ammonium(NH_(4)^(+)),mainly produced from the reactions of ammonia(NH_(3))with acids in the atmosphere,has significant impacts on air pollution,radiative forcing,and human health.Understanding the source and formation mechanism of NH_(4)^(+)can provide scientific insights into air quality improvements.However,the sources of NH_(3)in urban areas are not well understood,and few studies focus on NH_(3)/NH_(4)^(+)at different heights within the atmospheric boundary layer,which hinders a comprehensive understanding of aerosol NH_(4)^(+).In this study,we perform both field observation and modeling studies(the Community Multiscale Air Quality,CMAQ)to investigate regional NH_(3)emission sources and vertically resolved NH_(4)^(+)formation mechanisms during the winter in Beijing.Both stable nitrogen isotope analyses and CMAQ model suggest that combustion-related NH_(3)emissions,including fossil fuel sources,NH_(3)slip,and biomass burning,are important sources of aerosol NH_(4)^(+)with more than 60%contribution occurring on heavily polluted days.In contrast,volatilization-related NH_(3)sources(livestock breeding,N-fertilizer application,and human waste)are dominant on clean days.Combustion-related NH_(3)is mostly local from Beijing,and biomass burning is likely an important NH_(3)source(~15%–20%)that was previously overlooked.More effective control strategies such as the two-product(e.g.,reducing both SO_(2)and NH_(3))control policy should be considered to improve air quality.展开更多
The community multiscale air quality (CMAQ) model was used to forecast air quality over the Pearl River Delta region from December 2013 to January 2014.The pollution forecasting performance of CMAQ coupled with two di...The community multiscale air quality (CMAQ) model was used to forecast air quality over the Pearl River Delta region from December 2013 to January 2014.The pollution forecasting performance of CMAQ coupled with two different meteorological models,i.e.,the global/regional assimilation and prediction system (GRAPES) and the fifth-generation mesoscale model (MM5),was assessed by comparison with observational data.The effects of meteorological factors and physicochemical processes on the forecast results were discussed through process analysis.The results showed that both models exhibited good performance but that of GRAPES-CMAQ was better.GRAPES was superior in predicting the overall variation tendencies of meteorological fields,but it showed large deviations in atmospheric pressure and wind speed.This contributed to the higher correlation coefficients of the pollutants with GRAPES-CMAQ but with greater deviations.The underestimations of nitrate and ammonium salt contributed to the underestimations of both particulate matter and extinction coefficients.Source emissions made the only positive contributions to surface layer SO2,CO,and NO.It was found that O3 originated primarily from horizontal and vertical transport and that its consumption was predominantly via chemical processes.Conversely,NO2 was found derived primarily from chemical production.展开更多
Located in the central area of the North China Plain, the Beijing-Tianjin-Hebei region experiences severe air pollution, especially for Hebei province with five cities among the top 10 cities with the worst air qualit...Located in the central area of the North China Plain, the Beijing-Tianjin-Hebei region experiences severe air pollution, especially for Hebei province with five cities among the top 10 cities with the worst air quality nationwide. However, less studies have investigated local and regional contributions to cities in Hebei in comparison to Beijing and Tianjin. In this study, a source-oriented version of the Community Multiscale Air Quality (CMAQ) model is used to quantify inter- and intra-province transport of PM_(2.5) in 11 cities within Hebei in 2017. PM_(2.5) and its components vary seasonally with high levels in winter and low levels in summer. Local contributions to total PM_(2.5) within cities are 23%–61%, while intra-province transport contributes 10%–30%, and inter-province transport contributes 23%–46%, with top contributors of Shandong (4%–22%), Henan (3%–15%) and Shanxi (2%–11%). The primary components in most cities are mainly from local sources (30%–80%), and the secondary components are mainly from inter-province contributions (30%–66%). Local sources have the highest contributions to total PM_(2.5) in Shijiazhuang (∼49%), followed by Shanxi (∼12%) and Xingtai (∼7%). Secondary components from local and intra-province emissions are the major cause of heavy pollution events. These results suggest that both local and regional joint control measures with neighboring cities and provinces are necessary for pollution reduction in Hebei cities.展开更多
文摘High-resolution modeling approach is increasingly being considered as a necessary step for improving the monitoring and predictions of regional air quality. This is especially true for highly urbanized region with complex terrain and land-use. This study uses Community Multiscale Air Quality （CMAQ） model coupled with MM5 mesoscale model for a comprehensive analysis to assess the suitability of such high-resolution modeling system in predicting ozone air quality in the complex terrains of Osaka, Japan. The 1-km and 3-kin grid domains were nested inside a 9-km domain and the domain with 1-km grid covered the Osaka region. High-resolution Grid Point Value-Mesoscale Model （GPV-MSM） data were used after suitable validation. The simulated ozone concentrations were validated and evaluated using statistical metrics using performance criteria set for ozone. Daily maxima of ozone were found better simulated by the 1-krn grid domain than the coarser 9-km and 3-km domains, with the maximum improvement in the mean absolute gross error about 3 ppbv. In addition, 1-km grid results fared better than other grids at most of the observation stations that showed noticeable differences in gross error as well as correlation. These results amply justify the use of the integrated high-resolution MM5-CMAQ modeling system in the highly urbanized region, such as the Osaka region, which has complex terrain and land-use.
基金This study was funded by the National Natural Science Foundation of China(Grant No.20921140095)International Science&Technology Cooperation Program of China(2010DFA21300).
文摘Energy consumption is a major cause of air pollution in Beijing,and the adjustment of the energy structure is of strategic importance to the reduction of carbon intensity and the improvement of air quality.In this paper,we explored the future trend of energy structure adjustment in Beijing till 2020,designed five energy scenarios focusing on the fuel substitution in power plants and heating sectors,established emission inventories,and utilized the Mesoscale Modeling System Generation 5(MM5)and the Models-3/Community Multiscale Air Quality Model(CMAQ)to evaluate the impact of these measures on air quality.By implementing this systematic energy structure adjustment,the emissions of PM_(10),PM_(2.5),SO_(2),NO_(x),and non-methane volatile organic compounds(NMVOCs)will decrease distinctly by 34.0%,53.2%,78.3%,47.0%,and 30.6%respectively in the most coalintensive scenario of 2020 compared with 2005.Correspondingly,MM5-Models-3/CMAQ simulations indicate significant reduction in the concentrations of major pollutants,implying that energy structure adjustment can play an important role in improving Beijing’s air quality.By fuel substitution for power plants and heating boilers,PM_(10),PM_(2.5),SO_(2),NO_(x),and NMVOCs will be reduced further,but slightly by 1.7%,4.5%,11.4%,13.5%,and 8.8%respectively in the least coal-intensive scenario.The air quality impacts of different scenarios in 2020 resemble each other,indicating that the potential of air quality improvement due to structure adjustment in power plants and heating sectors is limited.However,the CO_(2) emission is 10.0%lower in the least coal-intensive scenario than in the most coal-intensive one,contributing to Beijing’s ambition to build a low carbon city.Except for energy structure adjustment,it is necessary to take further measures to ensure the attainment of air quality standards.
基金supported by the National Key R&D Program of China:Task 3(Grant No.2016 YFC0202000)Guangzhou Science and Technology Plan(Grant No.201604020028)+3 种基金National Natural Science Foundation of China(Grant No.41775037 and 41475105)Science and Technology Innovative Research Team Plan of Guangdong Meteorological Bureau(Grant No.201704)Guangdong Natural Science FoundationMajor Research Training Project(2015A030308014)a science and technology study project of Guangdong Meteorological Bureau(Grant No.2015Q03)
文摘Historical haze episodes（2013–16） in Guangzhou were examined and classified according to synoptic weather systems.Four types of weather systems were found to be unfavorable, among which ＂foreside of a cold front＂（FC） and ＂sea high pressure＂（SP） were the most frequent（〉 75% of the total）. Targeted case studies were conducted based on an FC-affected event and an SP-affected event with the aim of understanding the characteristics of the contributions of source regions to fine particulate matter（PM（2.5）） in Guangzhou. Four kinds of contributions—namely, emissions outside Guangdong Province（super-region）, emissions from the Pearl River Delta region（PRD region）, emissions from Guangzhou–Foshan–Shenzhen（GFS region）, and emissions from Guangzhou（local）—were investigated using the Weather Research and Forecasting–Community Multiscale Air Quality model. The results showed that the source region contribution differed with different weather systems. SP was a stagnant weather condition, and the source region contribution ratio showed that the local region was a major contributor（37%）, while the PRD region, GFS region and the super-region only contributed 8%, 2.8% and 7%, respectively, to PM（2.5） concentrations. By contrast, FC favored regional transport. The super-region became noticeable,contributing 34.8%, while the local region decreased to 12%. A simple method was proposed to quantify the relative impact of meteorology and emissions. Meteorology had a 35% impact, compared with an impact of-18% for emissions, when comparing the FC-affected event with that of the SP. The results from this study can provide guidance to policymakers for the implementation of effective control strategies.
文摘As an exercise in model sensitivity, the Models-3 Community Multiscale Air Quality (CMAQ) modeling system with meteorological fields from the Regional Atmospheric Modeling System (RAMS) was applied to study the response of photochemical oxidants to systematic increases in anthropogenic volatile organic compounds (VOC) and nitrogen oxides (NO x) emissions in January 1997 over East Asia. Three simulations-one base case and two sensitivity simulations were carried out. Two sensitivity simulations were performed by assuming a 35% separate increase in anthropogenic VOC and NO x emissions comparing with the base case. Biogenic VOC emissions were held constant across the sensitivity simulations. To evaluate the model performance, ozone mixing ratios (O 3) from the base case simulation were compared with surface observations at five remote sites in Japan, and it was found that the model reproduces most of the important features in the observations. Monthly average O 3 concentrations in the daytime were examined to gain an understanding of how the increase in anthropogenic emissions affected the overall chemical system for each sensitivity simulation.
基金supported by the National Natural Science Foundation of China(42130513,41905110,and 41961130384)the Royal Society Newton Advanced Fellowship,United Kingdom(NAFR1191220)the Research Grants Council of the Hong Kong Special Administrative Region,China(T24/504/17 and A-Poly U502/16)。
文摘Aerosol ammonium(NH_(4)^(+)),mainly produced from the reactions of ammonia(NH_(3))with acids in the atmosphere,has significant impacts on air pollution,radiative forcing,and human health.Understanding the source and formation mechanism of NH_(4)^(+)can provide scientific insights into air quality improvements.However,the sources of NH_(3)in urban areas are not well understood,and few studies focus on NH_(3)/NH_(4)^(+)at different heights within the atmospheric boundary layer,which hinders a comprehensive understanding of aerosol NH_(4)^(+).In this study,we perform both field observation and modeling studies(the Community Multiscale Air Quality,CMAQ)to investigate regional NH_(3)emission sources and vertically resolved NH_(4)^(+)formation mechanisms during the winter in Beijing.Both stable nitrogen isotope analyses and CMAQ model suggest that combustion-related NH_(3)emissions,including fossil fuel sources,NH_(3)slip,and biomass burning,are important sources of aerosol NH_(4)^(+)with more than 60%contribution occurring on heavily polluted days.In contrast,volatilization-related NH_(3)sources(livestock breeding,N-fertilizer application,and human waste)are dominant on clean days.Combustion-related NH_(3)is mostly local from Beijing,and biomass burning is likely an important NH_(3)source(~15%–20%)that was previously overlooked.More effective control strategies such as the two-product(e.g.,reducing both SO_(2)and NH_(3))control policy should be considered to improve air quality.
基金the National Key R&D Program of China (No.2016YFC0203305)Natural Science Foundation of China (41775037).
文摘The community multiscale air quality (CMAQ) model was used to forecast air quality over the Pearl River Delta region from December 2013 to January 2014.The pollution forecasting performance of CMAQ coupled with two different meteorological models,i.e.,the global/regional assimilation and prediction system (GRAPES) and the fifth-generation mesoscale model (MM5),was assessed by comparison with observational data.The effects of meteorological factors and physicochemical processes on the forecast results were discussed through process analysis.The results showed that both models exhibited good performance but that of GRAPES-CMAQ was better.GRAPES was superior in predicting the overall variation tendencies of meteorological fields,but it showed large deviations in atmospheric pressure and wind speed.This contributed to the higher correlation coefficients of the pollutants with GRAPES-CMAQ but with greater deviations.The underestimations of nitrate and ammonium salt contributed to the underestimations of both particulate matter and extinction coefficients.Source emissions made the only positive contributions to surface layer SO2,CO,and NO.It was found that O3 originated primarily from horizontal and vertical transport and that its consumption was predominantly via chemical processes.Conversely,NO2 was found derived primarily from chemical production.
基金supported by the co-fund DFG-NSFC Sino-German AirChanges project(No.448720203)National Natural Science Foundation of China(No.42077194 and No.42061134008)Shanghai International Science and Technology Partnership Project(No.21230780200).
文摘Located in the central area of the North China Plain, the Beijing-Tianjin-Hebei region experiences severe air pollution, especially for Hebei province with five cities among the top 10 cities with the worst air quality nationwide. However, less studies have investigated local and regional contributions to cities in Hebei in comparison to Beijing and Tianjin. In this study, a source-oriented version of the Community Multiscale Air Quality (CMAQ) model is used to quantify inter- and intra-province transport of PM_(2.5) in 11 cities within Hebei in 2017. PM_(2.5) and its components vary seasonally with high levels in winter and low levels in summer. Local contributions to total PM_(2.5) within cities are 23%–61%, while intra-province transport contributes 10%–30%, and inter-province transport contributes 23%–46%, with top contributors of Shandong (4%–22%), Henan (3%–15%) and Shanxi (2%–11%). The primary components in most cities are mainly from local sources (30%–80%), and the secondary components are mainly from inter-province contributions (30%–66%). Local sources have the highest contributions to total PM_(2.5) in Shijiazhuang (∼49%), followed by Shanxi (∼12%) and Xingtai (∼7%). Secondary components from local and intra-province emissions are the major cause of heavy pollution events. These results suggest that both local and regional joint control measures with neighboring cities and provinces are necessary for pollution reduction in Hebei cities.
