南京地区典型大气污染过程分析

文章统计分析了南京市近年来大气污染过程总体特征,选择2009-2011年不同类型的3个典型污染过程,分别讨论了其污染特征和影响因素.结果表明:以API值为污染判断指标,近年来南京市91%的污染过程持续时间在4 d以下,秋冬季节长时间污染过程更多。沙尘型污染受北方沙源地、长距离输送气象条件控制,影响范围广;秸秆燃烧型污染PM_(25)/PM_(10)浓度比例高达70%以上,细粒子(PM_(2.5))污染严重,主要受风向控制影响南京及周边局部地区,在降水冲刷或大风等气象条件下随污染源消失而快速消散;秋冬季的持续污染过程主要受气象条件影响,在均压场控制下,边界层呈局地性环流特征,污染物不断累积。

Analysis on Typical Atmospheric Pollution Process in Nanjing Area

General characteristics of air pollution process in Nanjing area were analyzed.Three different types of typical air pollution processes occurred in 2009-2011 were selected to analyze the characteristics and influence factors respectively.It was found mat 91%pollution process in Nanjing lasted for less than 4 days according to assessment indexes of API,and air pollution occurred in autumn and winter lasted longer.Pollution caused by dust event was mainly controlled by the sand source and long range transport meteorological condition,with wide affected area.The ratio of PM_(205)/PM_(10) reached up to 70% from the pollution of crop residue burning combined with high PM_(2.5) concentration.The wind direction is main factor influencing the pollution area,and the pollution decreased quickly with precipitation or strong wind,as well as disappearance of pollution source.Long duration air pollution in autumn and winter is related to the unfavorable weather condition,such as relative uniform pressure pattern,along with local circulation at the bottom boundary layer,resulting in the pollution accumulation.