2011年11月苏州一次灰霾天气过程分析

2011年11月10-14日苏州地区发生了一次严重灰霾天气过程，利用气象观测资料、探空资料及大气成分站监测资料对苏州三个站点的受污染情况进行了综合分析。结果表明：灰霾期间地面受弱气压场控制，风力较小，且有接地逆温的持续存在，大气水平和垂直输送都很弱，导致大量污染物在近地面堆积，能见度恶化；三站中昆山站灰霾持续时间最长，共计104时次，影响程度最重，重度灰霾占总数的39 %，中度和重度灰霾超过灰霾总数的一半；灰霾时各粒径颗粒物浓度均维持在较高水平，细粒子在可吸入颗粒物中占有较大比重，说明细粒子对灰霾贡献作用大，14日凌晨昆山及太仓出现大雾天气时细粒子比重甚至超过了灰霾时，而相对湿度峰值只有94 %，因此将该段天气定性为雾霾共存或者湿性霾更妥；秸秆焚烧污染期间，BC浓度明显上升，其绝对浓度要高出正常情况的3倍左右；通过CO/SO₂及PM₁₀/SO₂对比发现昆山站受秸秆焚烧污染程度要严重的多，因此推测昆山本地郊区可能也存在零星秸秆露天焚烧点。

Analysis of a haze weather process in November of 2011 in Suzhou

A serious haze weather process happened in Suzhou from November 10 to 14,2011. The polluted situa- tions at three stations in Suzhou were analyzed based on the meteorological observation data, sounding data and at- mospheric 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 ver- tical atmospheric transport is also weak. Thus, a lot of pollutants pile up near the ground and make visibility weak- ened. 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 se- vere haze excess 50% in Kunshan station. The concentrations of particles at different sizes are high during haze pe- riod. 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 early 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.