Atmospheric carbon dioxide is an important kind of greenhouse gas which influences global temperature.Its concentration variation could indicate the distribution of human and natural activities in various regions.Thro...Atmospheric carbon dioxide is an important kind of greenhouse gas which influences global temperature.Its concentration variation could indicate the distribution of human and natural activities in various regions.Through the non-dispersive infrared method,flask sampling of atmospheric CO_(2)concen-tration was measured weekly at four national background stations including Waliguan,Shangdianzi,Lin’an,and Longfengshan.Based on the data collected from September 2006 to August 2007,along with the Waliguan station’s experience on in situ observational data processing,the selection methods for sampling data through the atmospheric background CO_(2)concentration analysis were preliminarily discussed.On the basis of this result,the variation features of the four typical regions’atmospheric background CO_(2)concentration was analyzed for the first time.The results show that the atmospheric CO_(2)concentration at Waliguan,Shangdianzi,Lin’an,and Longfengshan is 383.5,385.9,387.8,and 384.3 ppm,respectively.During the research period,CO_(2)concentration at the Waliguan station changed slightly.However,the CO_(2)concentration changed sharply at the Shangdianzi and the Lin’an stations due to the great influence of human activities in the Jingjinji and the Changjiang Delta economic zones,and changed regularly with seasons at Longfengshan station under dual influences of human activities and plant photosynthesis.The results from this study can lay the foundation for more profound studies on atmospheric CO_(2)concentration level of different areas in China,and could be used to improve the understanding of carbon source and sink distribution.展开更多
Based on daily visibility data obtained from 1980-2002 and air pollution index data from 2001-2004 in Xi＇an, long-term variations and relationships for daily horizontal extinction coefficient and mass concentration o...Based on daily visibility data obtained from 1980-2002 and air pollution index data from 2001-2004 in Xi＇an, long-term variations and relationships for daily horizontal extinction coefficient and mass concentration of PM10 have been evaluated. A decreasing trend was found in horizontal extinction coefficient during the past 23 years, with higher values observed in 1980s relative to 1990s, and the highest and lowest values in winter and summer, respectively. Significant correlation and similar seasonal variations existed between horizontal extinction coefficient and PM10 concentration, suggesting the high influence of PM10 to the visibility drop at a site in the Guanzhong Plain of central China during the past two decades.展开更多
Based on 481-year records of historical dust storm （DS） and Dryness-Wetness Index （DWI） at 120 sites, spatial distribution characteristics of dryness-wetness （DW） in typical dust storm years （DS years） and in ...Based on 481-year records of historical dust storm （DS） and Dryness-Wetness Index （DWI） at 120 sites, spatial distribution characteristics of dryness-wetness （DW） in typical dust storm years （DS years） and in non-dust storm years （non-DS years） were derived for continental China. In DS years, most of the sites were drier than in normal years while in non-DS years wetter than normal, and the variation of DWI in DS years was larger than that in non-DS years. The relative instability and increased regional difference of atmospheric circulation in DS years might have induced more frequent DS events and dry-wet abnormality in continental China. In DS years the latitudinal （north-south） dry-wet difference was larger than that in non-DS years, that is, north China was even much drier than south China. This might be attributed to increased latitudinal differences of thermal and pressure gradients in DS years, resulting in the southward withdrawal of precipitation and increase of DS events.展开更多
基金Supported by National Natural Science Foundation of China(Grant No.40775078)National Non-profit Research Project to Serve the Public Interest(Grant No.GYHY200806026)International S&T Cooperation Program of MOST(Grant No.2007DFA20650)
文摘Atmospheric carbon dioxide is an important kind of greenhouse gas which influences global temperature.Its concentration variation could indicate the distribution of human and natural activities in various regions.Through the non-dispersive infrared method,flask sampling of atmospheric CO_(2)concen-tration was measured weekly at four national background stations including Waliguan,Shangdianzi,Lin’an,and Longfengshan.Based on the data collected from September 2006 to August 2007,along with the Waliguan station’s experience on in situ observational data processing,the selection methods for sampling data through the atmospheric background CO_(2)concentration analysis were preliminarily discussed.On the basis of this result,the variation features of the four typical regions’atmospheric background CO_(2)concentration was analyzed for the first time.The results show that the atmospheric CO_(2)concentration at Waliguan,Shangdianzi,Lin’an,and Longfengshan is 383.5,385.9,387.8,and 384.3 ppm,respectively.During the research period,CO_(2)concentration at the Waliguan station changed slightly.However,the CO_(2)concentration changed sharply at the Shangdianzi and the Lin’an stations due to the great influence of human activities in the Jingjinji and the Changjiang Delta economic zones,and changed regularly with seasons at Longfengshan station under dual influences of human activities and plant photosynthesis.The results from this study can lay the foundation for more profound studies on atmospheric CO_(2)concentration level of different areas in China,and could be used to improve the understanding of carbon source and sink distribution.
文摘Based on daily visibility data obtained from 1980-2002 and air pollution index data from 2001-2004 in Xi＇an, long-term variations and relationships for daily horizontal extinction coefficient and mass concentration of PM10 have been evaluated. A decreasing trend was found in horizontal extinction coefficient during the past 23 years, with higher values observed in 1980s relative to 1990s, and the highest and lowest values in winter and summer, respectively. Significant correlation and similar seasonal variations existed between horizontal extinction coefficient and PM10 concentration, suggesting the high influence of PM10 to the visibility drop at a site in the Guanzhong Plain of central China during the past two decades.
文摘Based on 481-year records of historical dust storm （DS） and Dryness-Wetness Index （DWI） at 120 sites, spatial distribution characteristics of dryness-wetness （DW） in typical dust storm years （DS years） and in non-dust storm years （non-DS years） were derived for continental China. In DS years, most of the sites were drier than in normal years while in non-DS years wetter than normal, and the variation of DWI in DS years was larger than that in non-DS years. The relative instability and increased regional difference of atmospheric circulation in DS years might have induced more frequent DS events and dry-wet abnormality in continental China. In DS years the latitudinal （north-south） dry-wet difference was larger than that in non-DS years, that is, north China was even much drier than south China. This might be attributed to increased latitudinal differences of thermal and pressure gradients in DS years, resulting in the southward withdrawal of precipitation and increase of DS events.
