Abstract:

Based on the hourly ground conventional observation data, hourly PM2.5 concentration, aerosol optical depth (AOD) from MODIS products, CALIPSO data in Nanjing and nearby areas and NCEP reanalysis data, the characteristics of a continuous fog and haze weather pollution episode from 4 to 9 December 2016 in Nanjing of Jiangsu Province were analyzed. The results showed that the continuous fog and haze weather had obvious regional features, the aerosols in Nanjing and nearby areas were mainly made from dust, polluted dust and continental pollutant, and the pollutants were mainly transported from Northwest China and discharged by the local people. The circulation background with uniform weak high pressure field on the ground and steady synoptic systems at high levels caused the fog and haze weather episode. Meanwhile, the divergence downdraft airflow controlled over Nanjing area, which was beneficial to maintenance of inversion layer, and then made the fog and haze weather to develop. With the invasion of cold air from the northerly wind, the positive vorticity advection controlled over Nanjing, which was beneficial to the weakening and disappearing of fog and haze. Moreover, the temperature advection affected the condensation of water vapor and relative humidity, thus led to the change of visibility.

Key words: fog and haze, concentration of PM_2.5, weather pattern, HYSPLIT model

摘要：

利用南京及其附近地区地面常规气象要素、颗粒物PM_2.5质量浓度逐时观测资料，以及CALIPSO资料、NCEP再分析资料、MODIS气溶胶光学厚度、南京站探空廓线等资料，结合天气学诊断分析和HYSPLIT后向轨迹模拟等方法，对2016年12月4—9日南京地区的一次雾霾天气进行分析。结果表明：此次雾霾天气过程具有区域性特征，南京上空气溶胶以沙尘型、污染沙尘型和污染大陆型为主，污染物主要来自西北方向的输送和本地的人为污染。地面弱高压均压场与高空稳定的天气形势叠加是此次雾霾天气过程的环流背景，同时南京上空盛行辐散下沉气流，下沉增温有利于逆温层的维持，使雾霾天气得以发展；偏北风携带的冷空气南下，正涡度平流控制南京上空，有利于雾霾的减弱消散，同时温度平流也影响了水汽凝结和相对湿度状况，进而使能见度发生相应变化。

关键词: 雾霾, 颗粒物PM_2.5质量浓度, 天气形势, HYSPLIT模式