Abstract:

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