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Research Getting Close to Understanding Beijing Haze
 Date: 2013-10-31  Page Views:

Severe haze pollution occurred in most of China's eastern regions in January 2013. The coverage was more than 1,300,000 km2.The population directly affected was about 850 million, while the population affected by serious pollution was about 250 million. However, due to the complexity of the atmospheric haze itself, the current knowledge on haze formation, development and dissipation is still insufficient, that severely limits the scientific decision making on haze pollution management and control.

Dr. LI Zhengqiang and his team in the Institute of Remote Sensing and Digital Earth (RADI), Chinese Academy of Sciences, published their new research results on remotely sensing of atmospheric haze EGU’s top journal Atmospheric chemistry and physics recently. Their study gave the new observation results of aerosol optical, physical, and chemical properties during winter heavy haze pollution in Beijing.

In this study, in view of the urgent requirements on mechanism and applications of real time, high accuracy, large coverage of haze remote sensing, they established the parameterized scheme to identify heavy haze pollution from remote sensing observations. Meanwhile, two winter heavy haze pollution periods in Beijing that occurred in 2011 and 2012 were selected and investigated by using ground-based remote sensing measurements. They developed models to derive aerosol optical, physical, and chemical parameters under heavy haze conditions. All those provided important references for haze monitoring and study. They also developed an advanced five-component (black carbon, brown carbon, mineral dust, ammonium sulfate-like component and aerosol water content) model to retrieve aerosol chemical composition fractions.

The study found that, Beijing winter haze dominated by small particles, with peak diameter of about 0.4 micron. A fine-mode particle fraction of 93% in optics proved that small particles dominate these polluted haze events, which are the main reason for visibility reduction. In addition, the radiation absorption of aerosol particles is relatively strong during heavy haze events, accounted for about 10% of total aerosol’s light extinction. That is obviously stronger than the radiation absorption in unpolluted days and lead to significant climate cooling, and to further suppress the atmospheric convection and diffusion of air pollution. Another feature of Beijing winter haze was the coexisting of dust and fly ash particles, with peak diameter of about 6 micron. Meanwhile, aerosol water content can reach up to about one-third in the total volume. This suggests that the air humidity played an important role in heavy haze formation.

The Chinese scientists of RADI led this study, while scientists from the United States and France participated in. This cooperation is established based on Chinese research conditions and aims at solving the serious air environmental problems in China. This study was joint supported by the National Natural Science Foundation of China (41222007) and the National Basic Research Program of China (973 program) under grant 2010CB950800 (2010CB950801). Focusing on the Beijing heavy haze pollution in January 2013, the team has published "haze remote sensing" special issue on the Journal of Remote Sensing ( recently. It provides a systematical introduction and report on the advanced approaches for monitoring of haze aerosols.

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