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Qi H.X.,Zhejiang University of Finance and Economics | Lin W.L.,Chinese Academy of Meteorological Sciences | Lin W.L.,Center for Atmosphere Watch and Services | Xu X.B.,Chinese Academy of Meteorological Sciences | And 2 more authors.
Science China Chemistry | Year: 2012

SO 2 is an important gas in atmosphere with great environmental and climate implications. SO 2 emission in China has been receiving great attention as the economy grows and the amount of coal consumption has increased in the past few decades. SO 2 has been observed from July 2005 to June 2010 at Linan WMO GAW regional station (30.3 °N, 119.73 °E, 138 m a.s.l.) located in the Yangtze Delta region in eastern China. These observation data are analyzed to understand the trend of regional SO 2 background concentration. Strict quality controls are conducted to ensure the temporal comparability of the data. Significant downward trend with -2.4 ppb/yr (P < 0.0001) of surface SO 2 is observed from 2005 to 2010, especially after 2008. The average concentration of SO 2 from July 2005 to June 2008 is 14.2±3.1 ppb, which is slightly higher than the mean values of 13.5±5.1 ppb during 1999-2000 and is two folds of the average value (7.1±3.1 ppb) from July 2008 to June 2010. More than 50% of the SO 2 has been cut down after 2008 in the Yangtze Delta region due to the implementation of stricter emission control measures. The peak SO 2 concentration appears around 10 o'clock in the morning after 2009 while appears at night before 2009. These diurnal variations of SO 2 might indicate that after 2009, more SO 2 is from the vertical exchange process than from the local accumulation. © Science China Press and Springer-Verlag Berlin Heidelberg 2012. Source

Cao N.,Nanjing University of Information Science and Technology | Zhu C.,Nanjing University of Information Science and Technology | Kai Y.,Nanjing University of Information Science and Technology | Yan P.,Center for Atmosphere Watch and Services
Applied Physics B: Lasers and Optics | Year: 2013

This paper applies a theoretical approach to the calculation of background noise levels during the analysis of lidar (light detection and ranging) data. We develop a method for the identification of background noise concealed within lidar signals under clear atmospheric or homogeneous aerosol layer conditions and derive an equation for the calculation of these noise levels from a theoretical consideration of the lidar equation. An increasing range-corrected signal indicates that a large amount of background noise exist in the return signal. We calculate the level of background noise by selecting three equidistant points in the return signal from the homogeneous layer and inputting the range and intensity of these points into the derived equation. Background noise calculations using actual lidar signals were in good agreement with calculations based on a simulated lidar signal. The background noise equation was verified using both observational lidar data and a simulated signal, indicating that it provides a reasonable measure of background noise levels in lidar data. © 2013 Springer-Verlag Berlin Heidelberg. Source

Ge B.Z.,CAS Institute of Atmospheric Physics | Xu X.B.,Chinese Academy of Meteorological Sciences | Lin W.L.,Chinese Academy of Meteorological Sciences | Lin W.L.,Center for Atmosphere Watch and Services | And 2 more authors.
Tellus, Series B: Chemical and Physical Meteorology | Year: 2012

Ambient measurements of SO 2, O 3, NO x, NO y and CO were made at Shangdianzi (SDZ), a rural site in the northeast (NE) of Beijing, and urban Beijing (China Meteorological Administration) from 1 June 2008 to 31 August 2008. The pollutants at SDZ showed very different levels under different wind conditions, with the levels under the southwest (SW) wind being much higher than those under the NE wind. The SW wind facilitates the transport of urban plume to SDZ, whereas the NE wind provides a background condition. At SDZ, theOzone(O 3) concentration in air masses from urban Beijing was found to be 33.490.4 ppbv higher than that from clean regions in summer. The ozone production efficiency (OPE x) for theurban plume and background condition was 4.0 and 5.3, respectively. Based on these OPE x values and the NOz values for the respective conditions, the contribution of in-situ production in the urban plume to the level of O 3 at SDZ is estimated to be 8.6 ppbv, corresponding only to 25.7% of the total impact of urban plume transport. This suggests that direct transport of O 3 rather than in-situ photochemistry contributes mainly to the summer elevation of the level of O 3 at SDZ. © 2012 B. Z. Ge et al. Source

Cao N.,Nanjing University of Information Science and Technology | Shi J.,Nanjing University of Information Science and Technology | Yang F.,Nanjing University of Information Science and Technology | Yan P.,Center for Atmosphere Watch and Services
Applied Physics B: Lasers and Optics | Year: 2012

This paper discusses the relationships among the aerosol extinction coefficient error (AECE), background noise, and distance associated with lidar measurements. The AECE calculation is explained in detail, revealing that the AECE is the product of background noise, range squared, and a relation function. The result of an AECE calculation that uses lidar measurements obtained in Nanjing, China, agrees with a calculation that uses a simulated lidar signal. The AECE equation is verified with lidar measurement data and a simulated lidar signal, indicating the AECE equation is reasonable. © The Author(s) 2012. Source

Ming J.,Chinese Academy of Sciences | Ming J.,National Climate Center | Xiao C.,Chinese Academy of Sciences | Sun J.,Chinese Academy of Sciences | And 4 more authors.
Journal of Environmental Sciences | Year: 2010

A continuous air and precipitation sampling for carbonaceous particles was conducted in a field observatory beside Nam Co, Central Tibetan Plateau during July of 2006 through January of 2007. Organic carbon (OC) was the dominant composition of the carbonaceous particles both in the atmosphere (1660 ng/m3) and precipitation (476 ng/g) in this area, while the average elemental carbon (BC) concentrations in the atmosphere and precipitation were only 82 ng/m3 and 8 ng/g, respectively. Very high OC/BC ratio suggested local secondary organic carbon could be a dominant contribution to OC over the Nam Co region, while BC could be mainly originated from Southern Asia, as indicated by trajectory analysis and aerosol optical depth. Comparison between the BC concentrations measured in Lhasa, those at " Nepal Climate Observatory at Pyramid (NCO-P)" site on the southern slope of the Himalayas, and Nam Co suggested BC in the Nam Co region reflected a background with weak anthropogenic disturbances and the emissions from Lhasa might have little impact on the atmospheric environment here, while the pollutants from the Indo-Gangetic Basin of Southern Asia could be transported to the Nam Co region by both the summer monsoon and the westerly. © 2010 The Research Centre for Eco-Environmental Sciences, Chinese Academy of Sciences. Source

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