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Liu H.-N.,Nanjing University | Zhu Y.,Suzhou Meteorological Service | Lin H.-J.,Suzhou Meteorological Service | Wang X.-Y.,Nanjing University
Zhongguo Huanjing Kexue/China Environmental Science | Year: 2015

The characteristics of haze weather in Suzhou were analyzed based on the hourly data from 2010 to 2013. The results show that the hourly frequency of haze is 30.7% (mostly slight haze), with the maximum haze frequency of 82.3% which is occurred in December of 2013. The ratio of dry haze to total haze is 85.6%. The hourly haze frequency shows obviously daily variation, the peak at 08:00 a.m. can reach 36.3%, and the minimum at 14:00~16:00 p.m. is approximately 25%. During the haze time, the values of PM10, PM2.5, PM1.0 and scatter coefficient are 1.72, 2.07, 1.88 and 2.58 times of that in no-haze time. The average haze day is in the range of 94 to 243 of one year because of the different standard for haze day. The meteorological conditions have significant influence on the haze frequency. When the relatively humidity is in the range of 70%~80%, the haze frequency is the biggest, but heavy haze are often occurred in the relatively humidity range of 90%~95%. Haze frequency of NW wind direction is the biggest and decrease gradually with the increase of wind speed. Particle scattering extinction is the most part of atmospheric extinction and accounted for about 82%, followed by absorption extinction of black carbon which is 13%. ©, 2015, Chinese Society for Environmental Sciences. All right reserved.

Yang K.,Nanjing University | Liu H.,Nanjing University | Zhu Y.,Suzhou Meteorological Service | Wang X.,Nanjing University | Lin H.,Suzhou Meteorological Service
Research of Environmental Sciences | Year: 2015

Hazy weather is a heavy pollution phenomenon in urban areas of China. The primary cause of the deterioration of visibility and the increase of haze is the enhancement of aerosol extinction caused by the increase of particle pollution in urban areas. Based on hourly observation data (including scattering coefficient, visibility, particle concentration, wind velocity and direction, temperature, pressure and humidity) from January 2010 to December 2013 in Suzhou City, aerosol scattering coefficient, extinction coefficient and their impact factors were analyzed. The results show that the average scattering coefficient in Suzhou City was (301.1±251.3) Mm-1, and there were two peaks in daily variation, one at 07:00-08:00 and the other at 20: 00-21: 00. The seasonal variation of scattering coefficient was also obvious: the highest one was in winter while the lowest one was in summer. The correlation coefficient between scattering coefficient and ρ(PM2.5) was 0.77, higher than those of ρ(PM10) and ρ(PM1). The mass scattering efficiency of PM2.5 was 6.08 m2/g. The relationship between scattering coefficient and some meteorological elements, such as wind direction and velocity, was also significant. When the wind velocity was less than 4 m/s, the scattering coefficient decreased rapidly with increasing wind velocity. When the wind velocity was between 4 and 6 m/s, the scattering coefficient decreased slowly with increasing wind velocity. The average single-scattering albedo and scattering-to-extinction ratios were 0.84 and 0.79, respectively, which showed that the aerosol extinction of Suzhou City was based on scattering of aerosol. The contribution to light extinction of aerosol scattering, aerosol absorbing, air molecules scattering and NO2 absorption were 82.33%, 13.63%, 2.72% and 1.32%, respectively. The most important reason for the deterioration of visibility and the increase of haze in Suzhou City was the nonabsorbable PM2.5, which contributed the most to the aerosol scattering extinction. ©, 2015, Editorial department of Molecular Catalysis. All right reserved.

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