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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.

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.

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.

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.

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.

Qu W.,Ocean University of China | Qu W.,Center for Atmosphere Watch and Services | Wang D.,CAS Institute of Earth Environment | Wang Y.,Center for Atmosphere Watch and Services | And 2 more authors.
Environmental Monitoring and Assessment | Year: 2010

Using observations from two remote sites during July 2004 to March 2005, we show that at Akdala (AKD, 47° 06' N, 87° 58' E, 562 m asl) in northern Xinjiang Province, there were high wintertime loadings of organic carbon (OC), elemental carbon (EC), and water-soluble (WS) SO2- 4, NO2- 3, and NH+ 4, which is similar to the general pattern in most areas of China and East Asia. However, at Zhuzhang (ZUZ, 28° 00' N, 99° 43' E, 3,583 m asl) in northwestern Yunnan Province, the aerosol concentrations and compositions showed little seasonal variation except for a decreasing trend of OC from August to autumn-winter. Additionally, the OC variations dominated the seasonal variation of PM 10 (par ticles ≤10 μm diameter) level. Chemical characteristics combined with transport information suggested sea salt origin of ionic Na +, Mg2+, and Cl- at ZUZ. At AKD, ionic Ca 2+, Mg2+, Na+, and Cl- primarily originated from salinized soil. Furthermore, the WS Ca2+ contributions (5.4-6%) to the PM10 mass during autumn, winter, and early spring reflected a constant dust component. The results of this study indicated that both sites were regionally representative. However, the representative regions and scales of these background sites may vary seasonally as the regional atmospheric transport patterns change. Seasonal variations in the background aerosol levels from these two areas need to be considered when evaluating the regional climate effects of the aerosols. © Springer Science + Business Media B.V. 2009.

Tao J.,South China Institute of Environmental Sciences | Gao J.,Chinese Research Academy of Environmental Sciences | Zhang L.,Environment Canada | Zhang R.,CAS Institute of Atmospheric Physics | And 6 more authors.
Atmospheric Chemistry and Physics | Year: 2014

Daily PM2.5(aerosol particles with an aerodynamic diameter of less than 2.5 samples were collected at an urban site in Chengdu, an inland megacity in southwest China, during four 1-month periods in 2011, with each period in a different season. Samples were subject to chemical analysis for various chemical components ranging from major water-soluble ions, organic carbon (OC), element carbon (EC), trace elements to biomass burning tracers, anhydrosugar levoglucosan (LG), and mannosan (MN). Two models, the ISORROPIA II thermodynamic equilibrium model and the positive matrix factorization (PMF) model, were applied to explore the likely chemical forms of ionic constituents and to apportion sources for PM2.5. Distinctive seasonal patterns of PM2.5 and associated main chemical components were identified and could be explained by varying emission sources and meteorological conditions. PM2.5 showed a typical seasonality of waxing in winter and waning in summer, with an annual mean of 119 Î1/4g 3. Mineral soil concentrations increased in spring, whereas biomass burning species elevated in autumn and winter. Six major source factors were identified to have contributed to PM 2.5 using the PMF model. These were secondary inorganic aerosols, coal combustion, biomass burning, iron and steel manufacturing, Mo-related industries, and soil dust, and they contributed 37 ± 18, 20 ± 12, 11 ± 10, 11 ± 9, 11 and plusmn; 9, and 10 ± 12%, respectively, to PM2.5 masses on annual average, while exhibiting large seasonal variability. On annual average, the unknown emission sources that were not identified by the PMF model contributed 1 ± 11% to the measured PM2.5 mass. Various chemical tracers were used for validating PMF performance. Antimony (Sb) was suggested to be a suitable tracer of coal combustion in Chengdu. Results of LG and MN helped constrain the biomass burning sources, with wood burning dominating in winter and agricultural waste burning dominating in autumn. Excessive Fe (Ex-Fe), defined as the excessive portion in measured Fe that cannot be sustained by mineral dust, is corroborated to be a straightforward useful tracer of iron and steel manufacturing pollution. In Chengdu, Mo/Ni mass ratios were persistently higher than unity, and considerably distinct from those usually observed in ambient airs. V/Ni ratios averaged only 0.7. Results revealed that heavy oil fuel combustion should not be a vital anthropogenic source, and additional anthropogenic sources for Mo are yet to be identified. Overall, the emission sources identified in Chengdu could be dominated by local sources located in the vicinity of Sichuan, a result different from those found in Beijing and Shanghai, wherein cross-boundary transport is significant in contributing pronounced PM2.5. These results provided implications for PM2.5 control strategies. © 2014 Author(s).

Tian P.,Beijing Normal University | Wang G.,Beijing Normal University | Zhang R.,Nanjing University of Information Science and Technology | Zhang R.,CAS Institute of Atmospheric Physics | And 2 more authors.
Particuology | Year: 2015

The optical properties of aerosols and their chemical composition, including water-soluble ions, organic carbon (OC), and elemental carbon (EC) in PM2.5 and PM10, were measured from 26 May to 30 June of 2012 at an urban site in Beijing. The daily average concentrations of PM2.5 and PM10 were 103.2 and 159.6 μg/m3, respectively. On average, the OC and EC contributed 20.1% and 4.3%, respectively, to PM2.5 and 16.3% and 3.9%, respectively, to PM10. Secondary ions (SO42-, NO3-, and NH4+) dominated the water-soluble ions and accounted for 57.9% and 62.6% of PM2.5 and PM10, respectively. The wind dependence of PM2.5, OC, SO42-, and NO3- implied that the pollution sources mainly came from south and southeast of Beijing during the summer. The monthly mean values of the scattering coefficient (σsc) and absorption coefficient (σab) at 525 nm were 312.9 and 28.7 Mm-1, respectively, and the mean single-scattering albedo (ω) was 0.85. The wind dependence of σsc revealed that this value was mainly influenced by regional transport during the summer, and the relationship between σab and wind indicated that a high σab resulted from the joint effects of local emissions and regional transport. The reconstructed σsc that was derived from the revised IMPROVE equation agreed well with the observations. The contribution of different chemical species to σsc was investigated under different pollution levels, and it was found that secondary inorganic aerosols accounted for a large part of σsc during pollution episodes (35.7%), while organic matter was the main contributor to σsc under clean conditions (33.6%). © 2014 Chinese Society of Particuology and Institute of Process Engineering, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.

Li Y.,Chinese Academy of Meteorological Sciences | Tang J.,Center for Atmosphere Watch and Services | Yu X.,Chinese Academy of Meteorological Sciences | Xu X.,Chinese Academy of Meteorological Sciences | And 2 more authors.
Environmental Science and Pollution Research | Year: 2012

Introduction: Trends in precipitation pH and conductivity during 1992-2009, and in ionic compositions from January 2007 to June 2009, are reported from Lushan Mountain, one of the highest mountains in mid-east China. Annual mean pH was in the range of 4.35-5.01 and showed a statistically very significant (P < 0.01) decreasing trend with time. Annual mean conductivity showed a statistically significant (P < 0.05) increasing trend, although this was not the case for non-H conductivity. Increasing rainwater acidity was mainly caused by increasing amounts of acid substances entering the rain. The trends in precipitation pH and conductivity were directly associated with energy consumption. Results and discussions: Over the period of study, Lushan Mountain received more rainfall in spring and summer. The pH values varied seasonally with winter minima. The winter multiyear seasonal mean pH was 4.35. The corresponding summer value was 4.88. SO4 2- and NO3 - were the main anions, and NH4 + and Ca2+ the main cations. The anion to cation ratio was 0.8-1.0, and that of [SO4 2-] to [NO3 -] was 2.4-3.0, much lower than that of the 1980s. However, sulfuric acid was still the main acid present. The ratio of [NH4 +] to [Ca2+] was about 1.0, suggesting that these two alkaline substances provided close acid neutralizing capacity. The ratio of [Cl-] to [Na+] was about 0.67, somewhat lower than that of natural precipitation. Conclusions: Ionic composition varied seasonally and was closely correlated to the amounts of rainfall and pollution. Trajectory analyses showed that the trajectories to Lushan Mountain could be classified in six clusters and trajectories originating from the South Sea and the areas surrounding Lushan Mountain had the greatest impacts on precipitation chemistry. © 2012 Springer-Verlag.

Ma J.,Chinese Academy of Meteorological Sciences | Ma J.,Hong Kong University of Science and Technology | Lin W.L.,Chinese Academy of Meteorological Sciences | Lin W.L.,Center for Atmosphere Watch and Services | And 4 more authors.
Atmospheric Chemistry and Physics | Year: 2014

In situ measurements of ozone (O3), carbon monoxide (CO) and meteorological parameters were made from December 2007 to November 2009 at the Xianggelila Regional Atmosphere Background Station (28.006° N, 99.726° E; 3580 m a.s.l.), southwest China. It was found that both O3 and CO peaked in spring while the minima of O3 and CO occurred in summer and winter, respectively. A normalized indicator (marked as "Y") on the basis of the monthly normalized O3, CO and water vapor, is proposed to evaluate the occurrence of O3 downward transport from the upper, O3-rich atmosphere. This composite indicator has the advantage of being less influenced by the seasonal or occasional variations of individual factors. It is shown that the most frequent and effective transport occurred in winter (accounting for 39% of the cases on the basis of a threshold of the Y value larger than 4) and they can make a significant contribution to surface O3 at Xianggelila. A 9.6 ppb increase (21.0%) of surface ozone is estimated based on the impact of deep downward transport events in winter. A case of strong O3 downward transport event under the synoptic condition of a deep westerly trough is studied by the combination of the Y indicator, potential vorticity, total column ozone and trajectory analysis. Asian monsoon plays an important role in suppressing O3 accumulation in summer and fall. The seasonal variation of O3 downward transport, as suggested by the Y indicator at Xianggelila, is consistent with the seasonality of stratosphere-to-troposphere transport and the subtropical jet stream over the Tibetan Plateau.

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