HR: 0800h
AN: A51B-0346    [Abstracts]
TI: The mechanism of visibility degradation over urban clusters in China
AU: * Zhuang, G
EM: gzhuang@fudan.edu.cn
AF: Center for Atmospheric Chemistry Study, Department of Environmental Science and Engineering, Fudan University, 220 Handan Rd., Shanghai, SH 200433, China
AU: Lin, Y
EM: 061047008@fudan.edu.cn
AF: Center for Atmospheric Chemistry Study, Department of Environmental Science and Engineering, Fudan University, 220 Handan Rd., Shanghai, SH 200433, China
AU: Li, J
EM: juanli0817@163.com
AF: Center for Atmospheric Chemistry Study, Department of Environmental Science and Engineering, Fudan University, 220 Handan Rd., Shanghai, SH 200433, China
AB: In many urban clusters in China there has been a new weather pattern, heavy haze with much lower visibility, occurred for 1/3 to 1/2 of days of the whole year in the past several years. The megacity, Shanghai, located in the center of the urban cluster areas in the Yangtze River Delta, experiencing severe visibility degradation in recent years, is taken as the typical city to investigate the mechanism of visual range degradation over the urban cluster in China. Aerosol samples were collected in Shanghai in four seasons from the spring of 2004 to the winter of 2005. Daily average particle mass, concentration of soluble ions species and black carbon and the time-matched meteorological data were subjected to analysis the visual range degradation contributors by multivariate linear regression. Water soluble ions and relative humidity (RH) were identified as the major contributors to visual range reduction. NH 4+ with RH was identified as the major contributor to visual range reduction in a lower relative humidity (spring and winter), while SO42- with RH was the major contributor in a higher humidity ambient (summer and autumn) . This might attribute to the hygroscopic species in fine particles. The haze days in spring, autumn and winter were generally influenced by air mass from inland emission. In spring, it was mainly due to the long range transport dust from north-northwest China , and in autumn and winter, the air mass generally came from the middle China. In haze days, the concentration of SO2 and NO2 in autumn and winter were all higher than that in spring, indicating that the gas-particle process were more significant in these two seasons, and contributed to the visual range degradation. In summer, air mass originated from ocean passing through south China arrived Shanghai would result in low visibility. The visibility degradation in Shanghai was largely influenced by the secondary aerosol of both local and regional emissions as well as long-range transport.
DE: 0305 Aerosols and particles (0345, 4801, 4906)
DE: 0335 Ion chemistry of the atmosphere (2419, 2427)
DE: 0345 Pollution: urban and regional (0305, 0478, 4251)
DE: 0365 Troposphere: composition and chemistry
SC: Atmospheric Sciences [A]
MN: 2007 Fall Meeting