Abstract: A serious haze weather process happened in Suzhou from November 11 to 14, 2011. The polluted situations at three stations in Suzhou were analyzed based on the meteorological observation data, sounding data and atmospheric composition monitoring data. The results show that it is controlled by weak air pressure on the ground during haze period with light wind; inversion temperature near the ground exists continually; the horizontal and vertical atmospheric transport is also weak. Thus, a lot of pollutants pile up near the ground and make visibility weakened. Among three stations, the duration of haze is longest in Kunshan station; it sums up to 104 times; the effect of haze is the most serious. The ratio of severe haze accounts for 39 % of the total, and those of the medium and severe haze excess 50 % in Kunshan station. The concentrations of particles at different sizes are high during haze period. The fine particles account for larger proportion among inhable particles, and it suggests that its contribution is obvious. The proportion of fine particles is larger in serious fog weather in the morning on November 14 at Kunshan and Taicang than in haze weather, while the peak value of relative humidity is only 94 %, so this weather process should be called as coexisted fog haze weather or wet haze weather. The concentrations of black carbon (BC) increase obviously during straw burning period and its absolute concentrations are three times higher than that in the normal situation. The comparison between CO/SO₂ and PM₁₀/SO₂ shows that the pollution from straw burning at Kunshan station is more serious, so it could be speculated that there exists other straw burning points in local suburbs.

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