苏南地区连续霾及重度霾的边界层气候特征

利用无锡国家基本观测站1981~2011年地面观测资料及南京、上海和杭州3个探空站的温度廓线资料，对苏南地区连续霾和重度霾的地面形势和边界层气候特征进行了分析。结果表明：苏南地区霾日地面形势主要为均压区型、高压底部或入海高压后部型、冷锋前部型、低压倒槽型和鞍型场；根据地面形势场的变化，连续9 d以上霾分4种类型，这4种类型具有不同的边界层结构变化：Ⅰ型苏南地区受两次大陆高压系统的南压（冷空气的过境），随后分别处于均压区中，该类型逆温层底较低，中层出现逆湿区；Ⅱ型苏南地区受大陆高压底部影响，随着冷空气的南下消退，大陆高压东移入海，苏南处于均压区中，该类型主要以等温层的形势出现，高湿区主要在底层；Ⅲ型随着长江中上游低压倒槽的发展，大陆高压入海后，苏南地区处于低压倒槽顶部，随着冷空气的南下，苏南地区先后受到均压区、高压底部影响，该类型总体逆温强度较弱，逆温层厚度较薄，低层高湿区贯穿于整个连续霾日过程；Ⅳ型主要受西太平洋暖高压、东北冷涡以及西伯利亚冷空气的共同作用，苏南地区随后处于冷锋前部，待冷空气过境后苏南又位于均压区中，该类型逆温强度较强，逆温层顶有逆湿区，逆温层高度越低，地面能见度越低，逆温层强度越强，地面能见度越低；重度霾出现的地面形势主要为均压区、冷锋前部和低压倒槽，重度霾大部分过程逆温层底在近地面，由于本地污染源的排放和外地污染源的侵入，加上逆温或等温层的存在，不利于污染物的扩散，以及底层大湿区，颗粒物的吸湿增长膨大，从而降低地面能见度，形成重度霾

BOUNDARY LAYER CLIMATE CHARACTERISTIC OF THE CONSECUTIVE HAZE AND THE HEAVY HAZE ON SOUTH OF JIANGSU AREA

The characteristics of the surface situation and the boundary layer climate with consecutive haze and the heavy haze over south Jiangsu were analyzed based on surface observations obtained from Wuxi Meteorological Station and temperature profile obtained from Nanjing, Shanghai and Hangzhou sounding stations during 1981-2011. The main surface situations in haze days were isobaric pressure, back of the high pressure, cold front, inverted trough with low pressure and saddle field. According to the variation of the surface situation, the nine consecutive haze days could be divided into four types which had different boundary layer structures. The high pressure went across the south of Jiangsu which would be controled by isobaric pressure with typeⅠ. In this type, the bottom of the temperature inversion layer was lower and there appeared inverse humidity areas in the middle level. Accompany by the high pressure motion, the south of Jiangsu was controled by the bottom of the high and then the cold front and the isobaric pressure in type Ⅱ. At the same time, the main situation was isothermal layer and the high humility areas was main on the ground. 〖JP2〗In type Ⅲ, there was inverted trough growing in the middle and lower reaches of the Yangtze River, accompaned by the high going to the sea, the south of Jiangsu located in the top of the inverted trough. Then by the cold air flowing to the south, isobaric pressure and the bottom of the high pressure took over the south of Jiangsu area one by one. The intensity and the thickness of the temperature inversion was weaker and thiner, at the same time the high humility on the low layer went through the whole days in type Ⅲ. In type Ⅳ, it was affected by the warm high on the west of the pacific, the cold vortex at the north east of China and the cold air from the Siberia in the south of Jiangsu which was controlled by the cold front and then the isobaric pressure. The intensity of the temperature inversion was stronger with this type meanwhile there was inverted humility at the top of the temperature inversion. The lower and the stronger of the height and the intensity of the temperature inversion layer, the lower ground visibility appeared. The main surface situations when the heavy haze occurred also were isobaric pressure, cold front and inverted trough with low pressure. In most of the heavy haze days, the bottom of the temperature inversion was near the ground. When the temperature inversion or isothermal existed and the high moisture appearred on the ground, the pollutant could not spreaded and the particulate matter expanded by taking in the water vapour. And then the ground visibility was lower and the heavy haze occurred