Based on data of PM2.5 hourly concentration and HYSPLIT model backward trajectory in coastal cities of Fujian Province during January 25 -26, 2014, a typical regional pollution process affecting Fujian from the north ...Based on data of PM2.5 hourly concentration and HYSPLIT model backward trajectory in coastal cities of Fujian Province during January 25 -26, 2014, a typical regional pollution process affecting Fujian from the north to the south and the east to the west on January 26 was investiga- ted. Taking Fuzhou as an example, based on weather situation on the ground and at high altitudes as well as corresponding meteorological data such as wind direction, wind velocity, and visibility, the changes of meteorological elements before, during and after the pollution were compared. Based on the V-3θ atmospheric vertical structure diagrams, the weather reasons for the generation, maintaining and dissipation of the pollution were discussed. The results indicated that the regional pollution was transported from the northeast to the southwest. The northeasterly air flow in front of the cold ridge strengthened and moved toward the east, so that the pollutant from the north affected Fujian form the north to the south and from the east to the west. As a result, there was a dramatic increase of pollutant concentration, rapid drop of visibility, and deterioration of air quality in the affected areas. The heavy pollution process featured high-speed transport and short-time generation. The air quality changed from good state to heavy pollution in just 3 -4 hours. The maximum of IAQIpM2.5 reached 280. The whole pollution process lasted for 14 hours. Solar radiation had been deeply affected by aerosol clouds, so that atmospheric stratification was extremely stable. Along with the eastward movement of cold high pressure into the sea, the dominant wind direction near the ground changed from the northeast to the east, so that the source of the pollutant was cut off , and air quality quickly turned well. The changes of atmospheric vertical structure indicated that the high inversion layer and clouds near 700 hPa kept lower air clean and blocked upper pollution transport. The later sudden increase of wind speed and strengthening of atmospheric mechanical turbu- lent destroyed inversion layer, so that the upper pollutants invaded air near the ground rapidly. During the period of high pollution, the isothermal layer (aerosol clouds) leaded to decrease of wind speed, and the atmosphere became more stable. The pollution ended until the wind field changed.展开更多
The concentrations of CH4,N2O and CO_(2)at the sea level were observed from November 2007 to August 2008 in order to study the greenhouse gases in the Tianjin offshore area of Bohai Sea.CH4 concentrations varied from ...The concentrations of CH4,N2O and CO_(2)at the sea level were observed from November 2007 to August 2008 in order to study the greenhouse gases in the Tianjin offshore area of Bohai Sea.CH4 concentrations varied from 1.87 to 2.61 ppm with the highest value appearing in summer and the lowest in winter.The concentration range of N2O was 319.3 to 347.7 ppb,with the maximal value appearing in winter.CO_(2)was higher in the heating season than in non-heating season in this area.Concentrations of the three greenhouse gases in the study area exceeded the 2005 global background values.Backward trajectory model was used to analyze the sources.All three gases were influenced evidently by continental sources in the inshore area during the sampling periods.Every gas was compared with each other by correlation analysis,showing that the correlation of CO_(2)and N2O was more significant than to CH4 and their relationship with meteorological factors was consistent.It can be concluded these three greenhouse gases may be influenced by some similar sources,especially for CO2 and N2O.展开更多
文摘Based on data of PM2.5 hourly concentration and HYSPLIT model backward trajectory in coastal cities of Fujian Province during January 25 -26, 2014, a typical regional pollution process affecting Fujian from the north to the south and the east to the west on January 26 was investiga- ted. Taking Fuzhou as an example, based on weather situation on the ground and at high altitudes as well as corresponding meteorological data such as wind direction, wind velocity, and visibility, the changes of meteorological elements before, during and after the pollution were compared. Based on the V-3θ atmospheric vertical structure diagrams, the weather reasons for the generation, maintaining and dissipation of the pollution were discussed. The results indicated that the regional pollution was transported from the northeast to the southwest. The northeasterly air flow in front of the cold ridge strengthened and moved toward the east, so that the pollutant from the north affected Fujian form the north to the south and from the east to the west. As a result, there was a dramatic increase of pollutant concentration, rapid drop of visibility, and deterioration of air quality in the affected areas. The heavy pollution process featured high-speed transport and short-time generation. The air quality changed from good state to heavy pollution in just 3 -4 hours. The maximum of IAQIpM2.5 reached 280. The whole pollution process lasted for 14 hours. Solar radiation had been deeply affected by aerosol clouds, so that atmospheric stratification was extremely stable. Along with the eastward movement of cold high pressure into the sea, the dominant wind direction near the ground changed from the northeast to the east, so that the source of the pollutant was cut off , and air quality quickly turned well. The changes of atmospheric vertical structure indicated that the high inversion layer and clouds near 700 hPa kept lower air clean and blocked upper pollution transport. The later sudden increase of wind speed and strengthening of atmospheric mechanical turbu- lent destroyed inversion layer, so that the upper pollutants invaded air near the ground rapidly. During the period of high pollution, the isothermal layer (aerosol clouds) leaded to decrease of wind speed, and the atmosphere became more stable. The pollution ended until the wind field changed.
基金supported by"Integrative Investigation and Evaluation on Chinese Offshore Sea"set by State Oceanic Administration of People’s Republic of China
文摘The concentrations of CH4,N2O and CO_(2)at the sea level were observed from November 2007 to August 2008 in order to study the greenhouse gases in the Tianjin offshore area of Bohai Sea.CH4 concentrations varied from 1.87 to 2.61 ppm with the highest value appearing in summer and the lowest in winter.The concentration range of N2O was 319.3 to 347.7 ppb,with the maximal value appearing in winter.CO_(2)was higher in the heating season than in non-heating season in this area.Concentrations of the three greenhouse gases in the study area exceeded the 2005 global background values.Backward trajectory model was used to analyze the sources.All three gases were influenced evidently by continental sources in the inshore area during the sampling periods.Every gas was compared with each other by correlation analysis,showing that the correlation of CO_(2)and N2O was more significant than to CH4 and their relationship with meteorological factors was consistent.It can be concluded these three greenhouse gases may be influenced by some similar sources,especially for CO2 and N2O.
