Black carbon （BC） is a component of fine particulate matter （PM2.5）, associated with climate, weather, air quality, and people＇s health. However, studies on temporal variation of atmospheric BC concentration at b...Black carbon （BC） is a component of fine particulate matter （PM2.5）, associated with climate, weather, air quality, and people＇s health. However, studies on temporal variation of atmospheric BC concentration at background stations in China and its source area identification are lacking. In this paper, we use 2-yr BC observations from two background stations, Lin＇an （LAN） and Longfengshan （LFS）, to perform the investigation. The results show that the mean diurnal variation of BC has two significant peaks at LAN while different characteristics are found in the BC vari- ation at LFS, which are probably caused by the difference in emission source contributions. Seasonal variation of monthly BC shows double peaks at LAN but a single peak at LFS. The annual mean concentrations of BC at LAN and LFS decrease by 1.63 and 0.26 μg m 3 from 2009 to 2010, respectively. The annual background concentration of BC at LAN is twice higher than that at LFS. The major source of the LAN BC is industrial emission while the source of the LFS BC is residential emission. Based on transport climatology on a 7-day timescale, LAN and LFS stations are sensitive to surface emissions respectively in belt or approximately circular area, which are dominated by summer monsoon or colder land air flows in Northwest China. In addition, we statistically analyze the BC source regions by using BC observation and FLEXible PARTicle dispersion model （FLEXPART） simulation. In summer, the source regions of BC are distributed in the northwest and south of LAN and the southwest of LFS. Low BC concentration is closely related to air mass from the sea. In winter, the source regions of BC are concentrated in the west and south of LAN and the northeast of the threshold area of stot at LFS. The cold air mass in the northwest plays an important role in the purification of atmospheric BC. On a yearly scale, sources of BC are approximately from five provinces in the northwest/southeast of LAN and the west of LFS. These findings are helpful in reducing BC emission and con- trolling air pollution.展开更多
Lorentz curve fittings are applied to frequency distributions of the concentrations of O3, CO, NOx and SO2 recorded at the Jinsha regional atmospheric background station （JSH） from June 2006 to July 2007, and the pe...Lorentz curve fittings are applied to frequency distributions of the concentrations of O3, CO, NOx and SO2 recorded at the Jinsha regional atmospheric background station （JSH） from June 2006 to July 2007, and the peak concentrations of these species for the different seasons are obtained. The peak concentrations are considered to be representative of different background levels for certain processes. The peak concentrations are compared with the corresponding mean （median） concentrations, and the suitability and limitations of the mean （median） values as the background levels are discussed. The mean （median） values might represent the background concentrations in the region under some circumstances, but in other cases these values often underestimate or overestimate the true background concentrations owing to the transport of pollutants and other factors. The effects of air masses transported from different regions on the pollutant background concentrations are obtained by analyzing the 72-hour backward trajectories of air masses 100m above the ground at JSH, These trajectories are estimated using the HYSPLIT model and then clustered for the measurement period. The spatial distribution and seasonal variations of trajectories and the corresponding mean concentrations of O3, SO〉 NOx and CO for different clusters are analyzed. After filtering the seasonal changes in pollutant concentrations, the relative influences of air masses from different regions are obtained. The results show that JSH can be used to obtain the atmospheric background information of different air masses originating from or passing over the Yangtze River Delta, Central South China and the Jianghan Plain. Air masses from Central China, South China, and the western Yangtze River Delta contribute significantly to O3 at JSH. Air masses from the north and northeast of JSH （i.e., the Jianghan Plain, Huang-Huai Plain and North China Plain） and the south （Central South China） contribute significantly to SO2, CO and NOx concentrations. Air masses originating from the ocean often bring clean air. Air masses originating from high altitudes over northwestern regions often have lower CO and NO3 concentrations, lower relative humidity, and higher concentrations of O3 and SO2.展开更多
Any accurate simulation of regional air quality by numerical models entails accurate and up-to-date emissions data for that region.The INTEX-B2006 （I06）,one of the newest emission inventories recently popularly used...Any accurate simulation of regional air quality by numerical models entails accurate and up-to-date emissions data for that region.The INTEX-B2006 （I06）,one of the newest emission inventories recently popularly used in China and East Asia,has been assessed using the Community Multiscale Air Quality model and observations from regional atmospheric background stations of China.Comparisons of the model results with the observations for the species SO2,NO 2,O 3 and CO from the three regional atmospheric background stations of Shangdianzi,Longfengshan and Linan show that the model can basically capture the temporal characteristics of observations such as the monthly,seasonal and diurnal variance trends.Compared to the other three species,the simulated CO values were grossly underestimated by about two-third or one-half of the observed values,related to the uncertainty in CO emissions.Compared to the other two stations,Shangdianzi had poorer simulations,especially for SO2 and CO,which partly resulted from the site location close to local emission sources from the Beijing area;and the regional inventory used was not capable of capturing the influencing factors of strong regional sources on stations.Generally,the fact that summer gave poor simulation,especially for SO2 and O 3,might partly relate to poor simulations of meteorological fields such as temperature and wind.展开更多
Ground-basedMulti-AXis Differential Optical Absorption Spectroscopy(MAX-DOAS)measurements were performed at Shangdianzi(SDZ)regional atmospheric background station in northern China from March 2009 to February 2011.Th...Ground-basedMulti-AXis Differential Optical Absorption Spectroscopy(MAX-DOAS)measurements were performed at Shangdianzi(SDZ)regional atmospheric background station in northern China from March 2009 to February 2011.The tropospheric NO_2vertical column densities(VCDs)were retrieved to investigate the background condition of the Beijing–Tianjin–Hebei developed economic circle in China.The seasonal variation of mean NO_2tropospheric VCDs(VCD_(Trop))at SDZ is apparent,with the maximum(1.3×10^(16)molec/cm^2)in February and the minimum(3.5×10^(15)molec/cm^2)in August,much lower than those observed at the Beijing city center.The average daytime diurnal variations of NO_2VCD_(Trop )are rather consistent for all four seasons,presenting the minimum at noon and the higher values in the morning and evening.The largest and lowest amplitudes of NO_2VCD_(Trop)diurnal variation appear in winter and in summer,respectively.The diurnal pattern at SDZ station is similar to those at other less polluted stations,but distinct from the ones at the urban or polluted stations.Tropospheric NO_2VCDs at SDZ are strongly dependent on the wind,with the higher values being associated with the pollution plumes from Beijing city.Tropospheric NO_2VCDs derived from ground-based MAX-DOAS at SDZ show to be well correlated with corresponding OMI(Ozone Monitoring Instrument)satellite products with a correlation coefficient R=0.88.However,the OMI observations are on average higher than MAX-DOAS NO_2VCDs by a factor of 28%,probably due to the OMI grid cell partly covering the south of SDZ which is influenced more by the pollution plumes from the urban areas.展开更多
长江三角洲在经济高速发展的同时,经历了较为严重的大气污染,受到了越来越多的关注.本研究于2009年4月(代表春季)、7月(代表夏季)和10月(代表秋季)在临安区域本底观测站使用低流量大气颗粒物采样器(FRM Omni sampler,BGI Inc.,USA)同步...长江三角洲在经济高速发展的同时,经历了较为严重的大气污染,受到了越来越多的关注.本研究于2009年4月(代表春季)、7月(代表夏季)和10月(代表秋季)在临安区域本底观测站使用低流量大气颗粒物采样器(FRM Omni sampler,BGI Inc.,USA)同步采集了PM_(2.5)和PM_(1.0)样品,并用离子色谱(IC)分析了样品中的水溶性无机离子(阴离子:F^-,Cl^-,NO_3^-,SO_4^(2-);阳离子:Na^+,NH_4^+,K^+,Mg^(2+),Ca^(2+)).结果表明:临安区域本底站PM_(2.5)和PM_(1.0)中水溶性无机离子总浓度夏季最低.NH_4^+、SO_4^(2-)和NO3-是最主要的无机离子,在PM_(2.5)中占水溶性无机离子总浓度的比值分别为78%(春季),85%(夏季)和80%(秋季),在PM_(1.0)中占水溶性无机离子总浓度的比值分别为78%(春季),83%(夏季),79%(秋季).NH_4^+和SO_4^(2-)的摩尔比均>2,表明SO_4^(2-)完全被NH_4^+中和,可能主要以(NH4)_2SO_4的形态存在.PM_(2.5)和PM_(1.0)中NO_3^-/SO_4^(2-)质量比的变化范围分别为0.31~0.84和0.44~0.63,说明临安市以固定源污染为主.展开更多
基金Supported by the International Cooperation Program of Ministry of Science&Technology of China(2015DFG21960)National Natural Science Foundation of China(41505123 and 41275167)+1 种基金Fundamental Research Fund of Chinese Academy of Meteorological Sciences(2015Y002)National(Key)Basic Research and Development(973)Program of China(2014CB441201)
文摘Black carbon （BC） is a component of fine particulate matter （PM2.5）, associated with climate, weather, air quality, and people＇s health. However, studies on temporal variation of atmospheric BC concentration at background stations in China and its source area identification are lacking. In this paper, we use 2-yr BC observations from two background stations, Lin＇an （LAN） and Longfengshan （LFS）, to perform the investigation. The results show that the mean diurnal variation of BC has two significant peaks at LAN while different characteristics are found in the BC vari- ation at LFS, which are probably caused by the difference in emission source contributions. Seasonal variation of monthly BC shows double peaks at LAN but a single peak at LFS. The annual mean concentrations of BC at LAN and LFS decrease by 1.63 and 0.26 μg m 3 from 2009 to 2010, respectively. The annual background concentration of BC at LAN is twice higher than that at LFS. The major source of the LAN BC is industrial emission while the source of the LFS BC is residential emission. Based on transport climatology on a 7-day timescale, LAN and LFS stations are sensitive to surface emissions respectively in belt or approximately circular area, which are dominated by summer monsoon or colder land air flows in Northwest China. In addition, we statistically analyze the BC source regions by using BC observation and FLEXible PARTicle dispersion model （FLEXPART） simulation. In summer, the source regions of BC are distributed in the northwest and south of LAN and the southwest of LFS. Low BC concentration is closely related to air mass from the sea. In winter, the source regions of BC are concentrated in the west and south of LAN and the northeast of the threshold area of stot at LFS. The cold air mass in the northwest plays an important role in the purification of atmospheric BC. On a yearly scale, sources of BC are approximately from five provinces in the northwest/southeast of LAN and the west of LFS. These findings are helpful in reducing BC emission and con- trolling air pollution.
基金supported by National Basic Research Program of China (Grant No. 2005CB4222002)Project of China Meteorological Administration (Grant No. GYHY[QX]200706005)National Natural Science Foundation of China (Grant No. 40705042)
文摘Lorentz curve fittings are applied to frequency distributions of the concentrations of O3, CO, NOx and SO2 recorded at the Jinsha regional atmospheric background station （JSH） from June 2006 to July 2007, and the peak concentrations of these species for the different seasons are obtained. The peak concentrations are considered to be representative of different background levels for certain processes. The peak concentrations are compared with the corresponding mean （median） concentrations, and the suitability and limitations of the mean （median） values as the background levels are discussed. The mean （median） values might represent the background concentrations in the region under some circumstances, but in other cases these values often underestimate or overestimate the true background concentrations owing to the transport of pollutants and other factors. The effects of air masses transported from different regions on the pollutant background concentrations are obtained by analyzing the 72-hour backward trajectories of air masses 100m above the ground at JSH, These trajectories are estimated using the HYSPLIT model and then clustered for the measurement period. The spatial distribution and seasonal variations of trajectories and the corresponding mean concentrations of O3, SO〉 NOx and CO for different clusters are analyzed. After filtering the seasonal changes in pollutant concentrations, the relative influences of air masses from different regions are obtained. The results show that JSH can be used to obtain the atmospheric background information of different air masses originating from or passing over the Yangtze River Delta, Central South China and the Jianghan Plain. Air masses from Central China, South China, and the western Yangtze River Delta contribute significantly to O3 at JSH. Air masses from the north and northeast of JSH （i.e., the Jianghan Plain, Huang-Huai Plain and North China Plain） and the south （Central South China） contribute significantly to SO2, CO and NOx concentrations. Air masses originating from the ocean often bring clean air. Air masses originating from high altitudes over northwestern regions often have lower CO and NO3 concentrations, lower relative humidity, and higher concentrations of O3 and SO2.
基金supported by the Chinese Ministry of Science and Technology(No.2011CB403404)the CAMS Basic Research Funds-regular(No.2010Y005)+1 种基金the Specific Team Fund of CAMS(No.2010Z002)the National Natural Science Foundation of China(No.40875086)
文摘Any accurate simulation of regional air quality by numerical models entails accurate and up-to-date emissions data for that region.The INTEX-B2006 （I06）,one of the newest emission inventories recently popularly used in China and East Asia,has been assessed using the Community Multiscale Air Quality model and observations from regional atmospheric background stations of China.Comparisons of the model results with the observations for the species SO2,NO 2,O 3 and CO from the three regional atmospheric background stations of Shangdianzi,Longfengshan and Linan show that the model can basically capture the temporal characteristics of observations such as the monthly,seasonal and diurnal variance trends.Compared to the other three species,the simulated CO values were grossly underestimated by about two-third or one-half of the observed values,related to the uncertainty in CO emissions.Compared to the other two stations,Shangdianzi had poorer simulations,especially for SO2 and CO,which partly resulted from the site location close to local emission sources from the Beijing area;and the regional inventory used was not capable of capturing the influencing factors of strong regional sources on stations.Generally,the fact that summer gave poor simulation,especially for SO2 and O 3,might partly relate to poor simulations of meteorological fields such as temperature and wind.
基金supported by the National Natural Science Foundation of China (Nos. 41505123, 41330422, 41075095)the CAMS Development Funds of Science and Technology (Nos. 2018KJ001, 2018KJ002)
文摘Ground-basedMulti-AXis Differential Optical Absorption Spectroscopy(MAX-DOAS)measurements were performed at Shangdianzi(SDZ)regional atmospheric background station in northern China from March 2009 to February 2011.The tropospheric NO_2vertical column densities(VCDs)were retrieved to investigate the background condition of the Beijing–Tianjin–Hebei developed economic circle in China.The seasonal variation of mean NO_2tropospheric VCDs(VCD_(Trop))at SDZ is apparent,with the maximum(1.3×10^(16)molec/cm^2)in February and the minimum(3.5×10^(15)molec/cm^2)in August,much lower than those observed at the Beijing city center.The average daytime diurnal variations of NO_2VCD_(Trop )are rather consistent for all four seasons,presenting the minimum at noon and the higher values in the morning and evening.The largest and lowest amplitudes of NO_2VCD_(Trop)diurnal variation appear in winter and in summer,respectively.The diurnal pattern at SDZ station is similar to those at other less polluted stations,but distinct from the ones at the urban or polluted stations.Tropospheric NO_2VCDs at SDZ are strongly dependent on the wind,with the higher values being associated with the pollution plumes from Beijing city.Tropospheric NO_2VCDs derived from ground-based MAX-DOAS at SDZ show to be well correlated with corresponding OMI(Ozone Monitoring Instrument)satellite products with a correlation coefficient R=0.88.However,the OMI observations are on average higher than MAX-DOAS NO_2VCDs by a factor of 28%,probably due to the OMI grid cell partly covering the south of SDZ which is influenced more by the pollution plumes from the urban areas.
文摘长江三角洲在经济高速发展的同时,经历了较为严重的大气污染,受到了越来越多的关注.本研究于2009年4月(代表春季)、7月(代表夏季)和10月(代表秋季)在临安区域本底观测站使用低流量大气颗粒物采样器(FRM Omni sampler,BGI Inc.,USA)同步采集了PM_(2.5)和PM_(1.0)样品,并用离子色谱(IC)分析了样品中的水溶性无机离子(阴离子:F^-,Cl^-,NO_3^-,SO_4^(2-);阳离子:Na^+,NH_4^+,K^+,Mg^(2+),Ca^(2+)).结果表明:临安区域本底站PM_(2.5)和PM_(1.0)中水溶性无机离子总浓度夏季最低.NH_4^+、SO_4^(2-)和NO3-是最主要的无机离子,在PM_(2.5)中占水溶性无机离子总浓度的比值分别为78%(春季),85%(夏季)和80%(秋季),在PM_(1.0)中占水溶性无机离子总浓度的比值分别为78%(春季),83%(夏季),79%(秋季).NH_4^+和SO_4^(2-)的摩尔比均>2,表明SO_4^(2-)完全被NH_4^+中和,可能主要以(NH4)_2SO_4的形态存在.PM_(2.5)和PM_(1.0)中NO_3^-/SO_4^(2-)质量比的变化范围分别为0.31~0.84和0.44~0.63,说明临安市以固定源污染为主.
