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Aerosol pollution in China:Present and future impact on environment

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Particuology 2009年第6期7卷 426-431页

作者： xuexi tie Junji Cao National Center for Atmospheric Research Boulder CO USA SKLLQG Institute of Earth Environment Chinese Academy of Sdences No. 10 Fenghui South Road High-Tech Zone Xi'an 710075. China

With its dense population, rapid economic growth and dramatic rate of urbanization, China is experiencing extreme air pollution problems. This is particularly the case in Central-Eastern China （CEC）, where the two major cities of Beijing and Tianjin are located, in the Yangtze-River Delta （YRD） with the city of Shanghai, and in the Pearl-River Delta （PRD） with the mega-city of Gnangzhou. Space observations show that the atmospheric aerosol load in these three regions is considerably higher than, for example, in the urbanized regions of Europe and North America. The high aerosol concentrations in these regions have raised many environmental problems, such as impact on human health, visibility, and climate changes. In this paper, several crucial issues regarding aerosol pollution in these highly populated regions （CEC, YRD, and PRD） are discussed, including （1） when the aerosol load starts to rapidly increase in these regions; （2） how the high aerosol concentrations affects the environment; and （3） what the potential consequences are under possible low aerosol load in these regions. Discussion on these crucial issues might lead to some insight for better understanding of the characterizations of aerosol pollution due to the rapid economical development in China.

关键词： Aerosols Environment China Present and future effects

Origin,evolution,and distribution of atmospheric aerosol particles in Asia

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Particuology 2015年第3期13卷 1-2页

作者： xuexi tie Key Laboratory of Aerosol Science and Technology SKLLQGInstitute of Earth EnvironmentChinese Academy of Sciences

In recent years, Asia became the region with the highest increase in rate of urbanization and economic development in the world. According to recent estimates from the United Nations, the world population will increase 36% between 2000 and 2030, leading to a doubling of the number of urban dwellers in less developed regions, like Asia. Such rapid economic development has many associated environmental problems, including development of heavy aerosol pollution over Asia.

关键词： Origin evolution and distribution of atmospheric aerosol particles in Asia

Possible effects of climate change of wind on aerosol variation during winter in Shanghai,China

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Particuology 2015年第3期13卷 80-88页

作者： Weidong Zhou xuexi tie Guangqiang Zhou Ping Liang Shanghai Center for Urban Environmental Meteorology Key Laboratory of Aerosol Science and Technology SKLLQGInstitute of Earth EnvironmentChinese Academy of Sciences National Center for Atmospheric Research Shanghai Climate Center

Several data sets were introduced to investigate the possible effects of climate-change-related variation of wind on aerosol concentration during winter in Shanghai, China. These data sets included the daily wind speed, wind direction, visibility, and precipitation from 1956 to 2010, hourly PM10 concentration from 2008 to 2010, and the NCEP/NCAR reanalysis data of global atmospheric circulation from 1956 to 2010. The trend of aerosol concentration and its correlations with wind speed and wind direction in winter were analyzed. Results indicated that there was an increase in the number of haze days in winter of 2.1 days/decade. Aerosol concentration, represented by PMl0 in this study, was highly correlated to both wind speed and direction in winter. The PMl0 concentration increased as wind speed decreased, reaching maximum values under static wind conditions. The PM10 concentration was relatively lower under easterly winds and higher under westerly winds. The analysis showed that weaker East Asia winter monsoons have resulted in a reduction of wind speed, increase in static wind frequency, and decline in the frequency of northerly winds since the 1980s. Moreover, the rapid expansion of urban construction in Shanghai has changed the underlying surface considerably, which has led to a reduction in wind speed. Finally, a wind factor was defined to estimate the combined effects of wind speed and wind direction on aerosol concentrations in Shanghai. The analysis of this factor indicated that changes in atmosphere circulation and urbanization have had important effects on the number of winter haze days in Shanghai.

关键词： AerosolWindClimate changeWinter monsoonShanghai

Analysis of the causes of heavy aerosol pollution in Beijing,China:A case study with the WRF-Chem model

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Particuology 2015年第3期13卷 32-40页

作者： Hui He xuexi tie Qiang Zhang Xiange Liu Qian Gao Xia Li Yang Gao Beijing Weather Modification Office Key Laboratory of Aerosol Science and Technology SKLLQGInstitute of Earth EnvironmentChinese Academy of Sciences National Center for Atmospheric Research

The causes and variability of a heavy haze episode in the Beijing region was analyzed. During the episode, the PM2.5 concentration reached a peak value of 450 μg/kg on January 18, 2013 and rapidly decreased to 100μg/kg on January 19, 2013, characterizing a large variability in a very short period. This strong vari- ability provides a good opportunity to study the causes of the haze formation. The in situ measurements （including surface meteorological data and vertical structures of the winds, temperature, humidity, and planetary boundary layer （PBL）） together with a chemical/dynamical regional model （WRF-Chem） were used for the analysis. In order to understand the rapid variability of the PM2.5 concentration in the episode, the correlation between the measured meteorological data （including wind speed, PBL height, relative humidity, etc.） and the measured particle concentration （PM2.5 concentration） was studied. In addition, two sensitive model experiments were performed to study the effect of individual contribution from local emissions and regional surrounding emissions to the heavy haze formation. The results suggest that there were two major meteorological factors in controlling the variability of the PM2.5 concentration, namely, surface wind speed and PBL height. During high wind periods, the horizontal transport of aerosol particles played an important role, and the heavy haze was formed when the wind speeds were very weak （less than 1 m/s）. Under weak wind conditions, the horizontal transport of aerosol particles was also weak, and the vertical mixing of aerosol particles played an important role. As a result, the PBL height was a major factor in controlling the variability of the PM2.5 concentration. Under the shallow PBL height, aerosol particles were strongly confined near the surface, producing a high surface PM2.5 concentration. The sensitivity model study suggests that the local emissions （emissions from the Beijing region only） were the major cause for

关键词： PM2.5 in BeijingCauses of heavy hazePlanetary boundary layer (PBL)WRF-Chem model

Attenuation of ultraviolet radiation reaching the surface due to atmospheric aerosols in Guangzhou

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Chinese Science Bulletin 2012年第21期57卷 2759-2766页

作者： DENG XueJiao ZHOU XiuJi tie xuexi WU Dui LI Fei TAN HaoBo DENG Tao Institute of Tropical and Marine Meteorology China Meteorological AdministrationGuangzhou 510080China Chinese Academy of Meteorological Sciences China Meteorological AdministrationBeijing 100081China National Center for Atmospheric Research BoulderCO 80307USA

The UV attenuation due to atmospheric aerosols in Guangzhou was quantitatively assessed using surface ultraviolet radiation (UV,295-385 nm) observation,sun photometer and radiation *** showed that the annual average value of aerosol optical depth (AOD) was 1.19 in UV spectral region of 340 nm,the annual average occurrence frequency of aerosol optical depth AOD 340 nm >1.0 was 55%,and the annual average attenuation rate of surface UV direct radiation of 340 nm was 68%.It was proven in the observation of surface UV radiation and model evaluation that annual average attenuation of UV due to atmosphere was 75%,and that reached 72% in the dry season (October,November,December and January);while average attenuation of UV due to atmospheric aerosols reached 62% in the dry *** was indicated that very significant UV attenuations due to atmospheric aerosols existed in Guangzhou urban agglomeration,and at least half of UV radiation was attenuated due to atmospheric *** large-amplitude attenuation will have a significant impact on urban ecosystem and species chemical cycles,especially photochemical reaction processes.

关键词：紫外线辐射大气气溶胶辐射衰减表面广州气溶胶光学厚度城市生态系统化学反应过程

Variability of SO_2 in an intensive fog in North China Plain:Evidence of high solubility of SO_2

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Particuology 2013年第1期11卷 41-47页

作者： Qiang Zhang xuexi tie Weili Lin Junji Cao Jiannong Quan Liang Ran Wanyun Xu Beijing Weather Modification Office Key Laboratory of Aerosol SKLLQGInstitute of Earth EnvironmentChinese Academy of Sciences Center for Atmospheric Research BoulderCOUSA Chinese Academy of Meteorological Science Department of Atmospheric and Oceanic Sciences School of PhysicsPeking University

A field experiment was conducted in an intensive fog event between November 5 and November 8, 2009, in a heavily SO2-polluted area in North China Plain （NCP）, to measure SO2 and other air pollutants, liquid water content （LWC） of fog droplets, and other basic meteorological parameters. During the fog period, the concentrations of SO2 showed large variability, which was closely related to the LWC in the fog droplets. The averaged concentration of SO2 during non-fog periods was about 25 ppbv, while during the fog period, it rapidly reduced to about 4-7 ppbv. Such large reduction of SO2 suggested that a majority of SO2 （about 70%-80%） had reverted from gas to aqueous phase on account of the high solubility of SO2 in water in the fog droplets. However, the calculated gas to aqueous phase conversion was largely underestimated by merely using the Henry＇s Law constant of SO2, thus suggesting that aqueous reaction of SO2 in fog droplets might play some important role in enhancing the solubility of SO2. To simplify the phenomenon, an ＂effective solubility coefficient＂ is proposed in this study. This variability of SO2 measurement during the extensive fog event provides direct evidence of oxidation of SO2 in fog droplets, thus providing important implications for better understanding of the acidity in clouds, precipitation, and fogs in NCP, now a central environmental focus in China due to its rapid economic development.

关键词： Solubility of SO2 Fogs in the North China Plain Aqueous phase reactions

Effect of atmospheric aerosol on surface ozone variation over the Pearl River Delta region

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Science China Earth Sciences 2011年第5期54卷 744-752页

作者： DENG XueJiao ZHOU XiuJi WU Dui tie xuexi TAN HaoBo LI Fei BI XueYan DENG Tao JIANG DeHai Institute of Tropical and Marine Meteorology Key Open Laboratory for Tropical Monsoon China MeteorologicalAdministration Guangzhou 510080 China Chinese Academy of Meteorological Sciences CMA Beijing 100081 China National Center for Atmospheric Research Boulder CO USA

Our analysis of the surface aerosol and ultraviolet （UV） measurements in Pearl River Delta （PRD） region shows that the surface UV radiation is reduced by more than 50% due to high aerosol concentrations. This has important impacts on urban ecosystem and photochemistry, especially on ozone photochemical production over the region. The quantitative effect of aerosols on surface ozone is evaluated by analyzing surface observations （including ozone, ultraviolet radiation, aerosol radiative parameters） and by using radiative and chemical models. A case study shows that the aerosol concentrations and UV radiation are significantly correlated with ozone concentrations. The correlation coefficient between the aerosol optical depth （AOD） and the PM10 mass concentration is very high, with a maximum of 0.98, and the AOD and UV radiation/ozone is anti- correlated, with a correlation coefficient of-0.90. The analysis suggests that ozone productivity is significantly decreased due to the reduction of UV radiation. The noon-time ozone maximum is considerably depressed when AOD is 0.6, and is further decreased when AOD is up to 1.2 due to the reduction of ozone photochemical productivity. Because the occurring probability of aerosol optical depth for AOD550m≥0.6 and AOD340mm ≥1.0 is 47, and 55% respectively during the dry season （October, November, December, January）, this heavy aerosol condition explains the low ozone maximum that often occurs in the dry season over the Guangzhou region. The analysis also suggests that the value of single scattering albedo （SSA） is very sensitive to the aerosol radiative effect when the radiative and chemical models are applied, implying that the value of SSA needs to be carefully studied when the models are used in calculating ozone production.

关键词： atmospheric aerosol ozone photochemical process attenuation

Evolution of planetary boundary layer under different weather conditions,and its impact on aerosol concentrations

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Particuology 2013年第1期11卷 34-40页

作者： Jiannong Quan Yang Gao Qiang Zhang xuexi tie Junji Cao Suqin Han Junwang Meng Pengfei Chen Delong Zhao Beijing Weather Modification Office Institude of Urban Meteorology CMA Key Laboratory of Aerosol SKLLQGInstitute of Earth EnvironmentChinese Academy of Sciences National Center for Atmospheric Research BoulderUSA Key Laboratory of Aerosol SKLLQGInstitute of Earth Environment.Chinese Academy of Sciences Tianjin Institute of Meteorological Sciences

A field experiment was conducted in Tianjin, China from September 9-30, 2010, focused on the evolution of Planetary Boundary Layer （PBL） and its impact on surface air pollutants. The experiment used three remote sensing instruments, wind profile radar （WPR）, microwave radiometer （MWR） and micro-pulse lidar （MPL）, to detect the vertical profiles of winds, temperature, and aerosol backscattering coefficient and to measure the vertical profiles of surface pollutants （aerosol, CO, SO2, NOx）, and also collected sonic anemometers data from a 255-m meteorological tower. Based on these measurements, the evolution of the PBL was estimated. The averaged PBL height was about 1000-1300 m during noon/afternoon-time, and 200-300 m during night-time. The PBL height and the aerosol concentrations were anti-correlated during clear and haze conditions. The averaged maximum PBL heights were 1.08 and 1.70 km while the averaged aerosol concentrations were 52 and 17 μg/m＆3 under haze and clear sky conditions, respectively, The influence of aerosols and clouds on solar radiation was observed based on sonic anemometers data collected from the 255-m meteorological tower. The heat flux was found significantly decreased by haze （heavy pollution） or cloud, which tended to depress the development of PBL, while the repressed structure of PBL further weakened the diffusion of pollutants, leading to heavy pollution. This possible positive feedback cycle （more aerosols→lower PBL height → more aerosols） would induce an acceleration process for heavy ground pollution in megacities.

关键词： Planetary boundary layer (PBL) Interaction between the PBL and aerosols

1st UMN-CAS Bilateral Seminar on PM_(2.5) science,health effects and control technology Xi'an,China,May 27-28,2014

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Particuology 2014年第5期12卷 227-229页

作者： Cao, Junji Pui, David Y. H. Kuehn, Thomas T. tie, xuexi Ramachandran, G. Zhu, Tong Wang, Jing Tao, Wenquan Chinese Acad Sci Inst Earth Environm Xian Peoples R China Univ Minnesota Minneapolis MN 55455 USA Peking Univ Beijing 100871 Peoples R China ETH CH-8093 Zurich Switzerland Empa CH-8600 Dubendorf Switzerland Xi An Jiao Tong Univ Xian 710049 Peoples R China

The First UMN-CAS Bilateral Seminar was successfully con- cluded with all the goals met. The meeting in Xi＇an was informative, stimulating and enjoyable, thanks to the local host, Prof. Junji Cao, and his capable staff. The Bilateral Seminar was organized by Prof. David Y.H. Pui of the University of Minnesota and Prof. Junji Cao of the Institute of Earth Environment, Chinese Academy of Sci- ences. It was attended by approximately 100 delegates from the University of Minnesota （UMN）, the Center for Filtration Research （CFR）, the Chinese Academy of Sciences （CAS） and other famous Chinese universities. We are grateful for the opening remarks given by UMN President Eric hai Li on behalf of President Kaler and CAS Vice President Jing- Chunli Bai.

关键词： PM UMN-CAS Bilateral Seminar on PM science,health effects and control technology Xi’an,China,May 27-28,2014 CAS