Stability parameters (Monin-Obukhov length L, gradient Richardson number Ri and bulk Rischardson number Ri), which are applicable in urban environment, were discussed for ways of calculating classification standards. ...Stability parameters (Monin-Obukhov length L, gradient Richardson number Ri and bulk Rischardson number Ri), which are applicable in urban environment, were discussed for ways of calculating classification standards. Gradient observations from a 325-m meteorological tower in Beijing are used to categorize Rib based on three different standards of stability proposed by D. Golder, Irwin and Houghton. The results show that it is relatively reasonable for the region of Beijing to apply the classification standard by Irwin.展开更多
The concentrations of polychlorinated biphenyls （PCBs） have been determined in soils collected in Beijing of China. According to Principle Component Analysis （PCA） of PCBs, the possible sources were studied. Relat...The concentrations of polychlorinated biphenyls （PCBs） have been determined in soils collected in Beijing of China. According to Principle Component Analysis （PCA） of PCBs, the possible sources were studied. Relationship between PCBs and soil organic materials revealed that higher chlorinated PCBs are more inclined to be adsorbed by particles rich of organic materials. But the low chlorinated homologues are dominant in Beijing soils, which is very different from the foreign studies. It was concluded that the application of relatively low chlorinated commercial PCBs in China was the main reason leading to this homologue composition character. Besides, the relatively short pollution history is also one of the main reasons. PCA of PCBs data in Beijing soil and atmospheric deposition samples revealed that some other emission sources such as atmospheric deposition, automobile exhaust; chemical and petrochemical industry and steel industry may be the important reasons of elevated PCBs concentrations in Beijing soil展开更多
The atmospheric mercury pollution in Beijing is a serious problem.Atmospheric mercury has three sources:natural emission,anthropogenic emission and previously deposited mercury reemission or recycling,composing elemen...The atmospheric mercury pollution in Beijing is a serious problem.Atmospheric mercury has three sources:natural emission,anthropogenic emission and previously deposited mercury reemission or recycling,composing elemental mercury,divalent mercury and particulate-phase mercury.Many studies showed that mercury in Beijing's air was higher than the general level of mercury concentration in the atmosphere.Mercury emission sources were discussed.Industrial emissions,coal burning,vehicle exhaust emissions and waste incineration were thought to be the main sources of atmospheric mercury pollution in Beijing.And also meteorology has an effect on atmospheric mercury concentration in Beijing.Measures have been taken to control the emission of mercury into the air in recent years.展开更多
China＇s environmental problems have become increasingly serious, which have caused great attention of the relevant departments of the state. Through the survey, we found that in most of the cities in our country, the...China＇s environmental problems have become increasingly serious, which have caused great attention of the relevant departments of the state. Through the survey, we found that in most of the cities in our country, the inhalable particulate matter PM10 is one of the main pollutants, especially in the capital of China -- Beijing, which is the arch-criminal cause of the air pollution. According to the quality control report released in Beijing City Environmental Protection Bureau, as can be learned, in recent years, Beijing＇s air quality goes from bad to worse, and in the overall atmospheric pollutants, the PM10 is up to above nine tenths. There are more reports saying that the air pollution levels in Beijing have been not suitable for the human habitation. With the increasing of the air pollution, the term PM2.5 is also more and more familiar to us. The air more intensified the pollution is, the greater the ratio of PM2.5 in PM10 is. In that case, it not only seriously affects the people＇s health, but also brings the huge economic losses. This paper is aimed to analyze the influence of PM2.5 on the economic situation of Beijing, and puts forward the concrete solutions.展开更多
Several multi-scale numerical simulation experiments were carried out using the mesoscale modeling systems MM5V3.7 and WRFV2.2 for Greater Beijing to estimate the accuracy of WRF and MM5 in simulating the characterist...Several multi-scale numerical simulation experiments were carried out using the mesoscale modeling systems MM5V3.7 and WRFV2.2 for Greater Beijing to estimate the accuracy of WRF and MM5 in simulating the characteristics and variations of mesoscale local circulation in the atmospheric boundary layer of this area. We simulated the horizontal distribution and diurnal variations of temperature and wind fields near the ground and compared them with Automatic Weather System (AWS) data collected from 19 AWS stations in Beijing. Correlation and error analyses were also made. The modeling and statistical results showed that both WRF and MM5 model the temperature field near the ground significantly better than they model the wind field. The temperature field simulated by MM5 is more coincident than that of WRF with the AWS observation records, while WRF does better than MM5 in simulating the wind field, especially under the condition of gusty wind. Neither WRF nor MM5 can capture the fine structure of urban architectural complexity, which is the main error in the wind field simulation. Both models underestimate the land surface temperature at night and overestimate the temperature during the day. All the above results are supported by statistical analysis.展开更多
Turbulence data(2008–2012) from a 325 m meteorological tower in Beijing, which consisted of three layers(47,140, and 280 m), was used to analyze the vertical distribution characteristics of turbulent transfer over Be...Turbulence data(2008–2012) from a 325 m meteorological tower in Beijing, which consisted of three layers(47,140, and 280 m), was used to analyze the vertical distribution characteristics of turbulent transfer over Beijing city according to similarity theory. The conclusions were as follows.(1) Normalized standard deviations of wind speeds/ui * were plotted as a function only of a local stability parameter. The values under near-neutral conditions were 2.15, 1.61, and 1.19 at 47 m, 2.39, 1.75,and 1.21 at 140 m, and 2.51, 1.77, and 1.30 at 280 m, showing a clear increase with height. The normalized standard deviation of wind components fitted the 1/3 law under unstable stratification conditions and decreased with height under both stable and unstable conditions.(2) The normalized standard deviation of temperature fitted the.1/3 law in the free convection limit, but was quite scattered with different characteristics under near-neutral conditions. The normalized standard deviations of humidity and the CO2 concentration fitted the.1/3 law under unstable conditions, and remained constant under near-neutral and stable stratification. The normalized standard deviation of scalars, i.e., temperature, humidity, and CO2 concentration, all increased with height.(3) Compared with momentum, and the water vapor and CO2 concentrations, the turbulence correlation coefficient for heat was smaller under near-neutral conditions, but larger under both stable and unstable conditions. A dissimilarity between heat, and the water vapor and CO2 concentrations was observed in urban areas. The relative correlation coefficients between heat and each of momentum, humidity, and CO2 concentration(|rwT/ruw|, |rwT/rwc| and |rwT/ruq|) in the lower layers were always larger than in higher layers, except for the relative correlation coefficient between heat and humidity in an unstable stratification. Therefore, the ratio between heat and each of momentum, humidity, and CO2 concentration decreased with height.展开更多
Nitrous acid （HONO）, as a primary precursor of OH radicals, has been considered one of the most important nitrogencontaining species in the atmosphere. Up to 30% of primary OH radical production is attributed to the...Nitrous acid （HONO）, as a primary precursor of OH radicals, has been considered one of the most important nitrogencontaining species in the atmosphere. Up to 30% of primary OH radical production is attributed to the photolysis of HONO. However, the major HONO formation mechanisms are still under discussion. During the Campaigns of Air Quality Research in Beijing and Surrounding Region （CAREBeijing2006） campaign, comprehensive measurements were carried out in the megacity Beijing, where the chemical budget of HONO was fully constrained. The average diurnal HONO concentration varied from 0.33 to 1.2 ppbv. The net OH production rate from HONO, Pon（HONO）net, was on average （from 05：00 to 19：00） 7.1 × 10^6 molecule/（cm^3 s）, 2.7 times higher than from 03 photolysis. This production rate demonstrates the important role of HONO in the atmospheric chemistry of megacity Beijing. An unknown HONO source （Punknown） with an average of 7.3 × 10^6 molecule/（cm^3 s） was derived from the budget analysis during daytime. Punknown provided four times more HONO than the reaction of NO with OH did. The diurnal variation of Punknown showed an apparent photo-enhanced feature with a maximum around 12：00, which was consistent with previous studies at forest and rural sites. Laboratory studies proposed new mechanisms to recruit NO2 and J（NO2） in order to explain a photo-enhancement of of Puknown. In this study, these mechanisms were validated against the observation-constraint Punknown. The reaction of exited NO2 accounted for only 6% of Puknown, and Punk poorly correlated with [NO2] （R = 0.26） and J（NO2）[NO2] （R = 0.35）. These results challenged the role of NO2 as a major precursor of the missing HONO source.展开更多
基金Open Foundation by the Guangzhou Institute of Tropical and Marine Meteorology, CMA
文摘Stability parameters (Monin-Obukhov length L, gradient Richardson number Ri and bulk Rischardson number Ri), which are applicable in urban environment, were discussed for ways of calculating classification standards. Gradient observations from a 325-m meteorological tower in Beijing are used to categorize Rib based on three different standards of stability proposed by D. Golder, Irwin and Houghton. The results show that it is relatively reasonable for the region of Beijing to apply the classification standard by Irwin.
基金Acknowledgements： The research was supported by Beijing Natural and Science Foundation.
文摘The concentrations of polychlorinated biphenyls （PCBs） have been determined in soils collected in Beijing of China. According to Principle Component Analysis （PCA） of PCBs, the possible sources were studied. Relationship between PCBs and soil organic materials revealed that higher chlorinated PCBs are more inclined to be adsorbed by particles rich of organic materials. But the low chlorinated homologues are dominant in Beijing soils, which is very different from the foreign studies. It was concluded that the application of relatively low chlorinated commercial PCBs in China was the main reason leading to this homologue composition character. Besides, the relatively short pollution history is also one of the main reasons. PCA of PCBs data in Beijing soil and atmospheric deposition samples revealed that some other emission sources such as atmospheric deposition, automobile exhaust; chemical and petrochemical industry and steel industry may be the important reasons of elevated PCBs concentrations in Beijing soil
文摘The atmospheric mercury pollution in Beijing is a serious problem.Atmospheric mercury has three sources:natural emission,anthropogenic emission and previously deposited mercury reemission or recycling,composing elemental mercury,divalent mercury and particulate-phase mercury.Many studies showed that mercury in Beijing's air was higher than the general level of mercury concentration in the atmosphere.Mercury emission sources were discussed.Industrial emissions,coal burning,vehicle exhaust emissions and waste incineration were thought to be the main sources of atmospheric mercury pollution in Beijing.And also meteorology has an effect on atmospheric mercury concentration in Beijing.Measures have been taken to control the emission of mercury into the air in recent years.
文摘China＇s environmental problems have become increasingly serious, which have caused great attention of the relevant departments of the state. Through the survey, we found that in most of the cities in our country, the inhalable particulate matter PM10 is one of the main pollutants, especially in the capital of China -- Beijing, which is the arch-criminal cause of the air pollution. According to the quality control report released in Beijing City Environmental Protection Bureau, as can be learned, in recent years, Beijing＇s air quality goes from bad to worse, and in the overall atmospheric pollutants, the PM10 is up to above nine tenths. There are more reports saying that the air pollution levels in Beijing have been not suitable for the human habitation. With the increasing of the air pollution, the term PM2.5 is also more and more familiar to us. The air more intensified the pollution is, the greater the ratio of PM2.5 in PM10 is. In that case, it not only seriously affects the people＇s health, but also brings the huge economic losses. This paper is aimed to analyze the influence of PM2.5 on the economic situation of Beijing, and puts forward the concrete solutions.
基金supported by National Natural Science Foundation of China (Grant No. 40875004)Urban Meteorology Scientific Research Fund Program of the Institute of Beijing Urban Meteorology, China Meteorological Administration (Grant No. UMRF200702)+2 种基金Public Welfare Special Fund Program (Meteorology) of China Scientific and Technological Ministry (Grant No. GYHY200806020)National Science and Technology Sustain Program (Grant No. 2008BAC37B00)Central Public Welfare Special Fund Program for the Institute and Higher Education (Grant No. IUMKY200701)
文摘Several multi-scale numerical simulation experiments were carried out using the mesoscale modeling systems MM5V3.7 and WRFV2.2 for Greater Beijing to estimate the accuracy of WRF and MM5 in simulating the characteristics and variations of mesoscale local circulation in the atmospheric boundary layer of this area. We simulated the horizontal distribution and diurnal variations of temperature and wind fields near the ground and compared them with Automatic Weather System (AWS) data collected from 19 AWS stations in Beijing. Correlation and error analyses were also made. The modeling and statistical results showed that both WRF and MM5 model the temperature field near the ground significantly better than they model the wind field. The temperature field simulated by MM5 is more coincident than that of WRF with the AWS observation records, while WRF does better than MM5 in simulating the wind field, especially under the condition of gusty wind. Neither WRF nor MM5 can capture the fine structure of urban architectural complexity, which is the main error in the wind field simulation. Both models underestimate the land surface temperature at night and overestimate the temperature during the day. All the above results are supported by statistical analysis.
基金supported by the National Nature Science Foundation of China (Grant Nos. 41275023, 91537212 & 410210040)
文摘Turbulence data(2008–2012) from a 325 m meteorological tower in Beijing, which consisted of three layers(47,140, and 280 m), was used to analyze the vertical distribution characteristics of turbulent transfer over Beijing city according to similarity theory. The conclusions were as follows.(1) Normalized standard deviations of wind speeds/ui * were plotted as a function only of a local stability parameter. The values under near-neutral conditions were 2.15, 1.61, and 1.19 at 47 m, 2.39, 1.75,and 1.21 at 140 m, and 2.51, 1.77, and 1.30 at 280 m, showing a clear increase with height. The normalized standard deviation of wind components fitted the 1/3 law under unstable stratification conditions and decreased with height under both stable and unstable conditions.(2) The normalized standard deviation of temperature fitted the.1/3 law in the free convection limit, but was quite scattered with different characteristics under near-neutral conditions. The normalized standard deviations of humidity and the CO2 concentration fitted the.1/3 law under unstable conditions, and remained constant under near-neutral and stable stratification. The normalized standard deviation of scalars, i.e., temperature, humidity, and CO2 concentration, all increased with height.(3) Compared with momentum, and the water vapor and CO2 concentrations, the turbulence correlation coefficient for heat was smaller under near-neutral conditions, but larger under both stable and unstable conditions. A dissimilarity between heat, and the water vapor and CO2 concentrations was observed in urban areas. The relative correlation coefficients between heat and each of momentum, humidity, and CO2 concentration(|rwT/ruw|, |rwT/rwc| and |rwT/ruq|) in the lower layers were always larger than in higher layers, except for the relative correlation coefficient between heat and humidity in an unstable stratification. Therefore, the ratio between heat and each of momentum, humidity, and CO2 concentration decreased with height.
基金supported by the National Natural Science Foundation of China(21190052,40675072,41121004)the Ministry of Science and Technology of China(2002CB410801)the Beijing Council of Science and Technology(HB200504-6,HB200504-2)
文摘Nitrous acid （HONO）, as a primary precursor of OH radicals, has been considered one of the most important nitrogencontaining species in the atmosphere. Up to 30% of primary OH radical production is attributed to the photolysis of HONO. However, the major HONO formation mechanisms are still under discussion. During the Campaigns of Air Quality Research in Beijing and Surrounding Region （CAREBeijing2006） campaign, comprehensive measurements were carried out in the megacity Beijing, where the chemical budget of HONO was fully constrained. The average diurnal HONO concentration varied from 0.33 to 1.2 ppbv. The net OH production rate from HONO, Pon（HONO）net, was on average （from 05：00 to 19：00） 7.1 × 10^6 molecule/（cm^3 s）, 2.7 times higher than from 03 photolysis. This production rate demonstrates the important role of HONO in the atmospheric chemistry of megacity Beijing. An unknown HONO source （Punknown） with an average of 7.3 × 10^6 molecule/（cm^3 s） was derived from the budget analysis during daytime. Punknown provided four times more HONO than the reaction of NO with OH did. The diurnal variation of Punknown showed an apparent photo-enhanced feature with a maximum around 12：00, which was consistent with previous studies at forest and rural sites. Laboratory studies proposed new mechanisms to recruit NO2 and J（NO2） in order to explain a photo-enhancement of of Puknown. In this study, these mechanisms were validated against the observation-constraint Punknown. The reaction of exited NO2 accounted for only 6% of Puknown, and Punk poorly correlated with [NO2] （R = 0.26） and J（NO2）[NO2] （R = 0.35）. These results challenged the role of NO2 as a major precursor of the missing HONO source.
