2019年昆明市一次臭氧污染过程特征及成因分析

Characteristics and reason analysis of ozone pollution process in Kunming in 2019

针对2019年4月22-26日昆明出现的臭氧污染过程,利用昆明空气质量数据、气象观测数据、NCEP及ERA5再分析资料,综合气象条件、天气形势、外源输送条件,分析本次污染过程的特征及其成因.结果表明:①本次臭氧污染过程O_(3)浓度呈“单峰型”变化,7:00-8:00出现每日的谷值,13:00-15:00出现每日的峰值.②高温低湿条件利于O_(3)的形成,温度为24~29℃,相对湿度为15%~35%,风向为东南风和西南风时O_(3)浓度易超标.③此次污染过程中存在O_(3)的水平和垂直外源输送,在天气系统的作用下,近地层静稳天气导致污染物的积累和生成,并利于将云南以西区域高浓度O_(3)向昆明上空水平输送;平流层下层-对流层上层的垂直入侵使高层含高浓度O_(3)的空气向对流层及近地层输送.④HYSPLIT后向轨迹进一步验证,污染过程外源输送的气团来源于云南以西的中低纬度地区,污染物浓度与气团移动路径及天气系统相吻合.

Based on the ozone pollution process in Kunming during 22-26 April 2019,the characteristics and reason analysis of ozone pollution was analyzed,from the aspects of meteorological conditions,weather situation,external transportation,using Kunming air quality data,meteorological observation data,NCEP and ERA5 reanalysis data.The results were follows:①The concentration of O_(3) showed a“single peak”,with a daily valley at 7:00-8:00 and a daily peak at 13:00-15:00.②High temperature and low humidity were favorable for the formation of O_(3),when the temperature was between 24℃and 29℃,the relative humidity was between 15%and 35%and the wind direction were southeast and southwest,the concentration of O_(3) would exceed standard easily.③There were horizontal and vertical external transport of O_(3),under the effect of weather systems,the stable weather near the ground was conducive to the accumulation and generation of pollutants.It was conducive to the horizontal transportation of high concentration O_(3) in the west of Yunnan to Kunming.The vertical invasion of the lower stratosphere and upper troposphere was conducive to the transport of high concentration O_(3) air to the troposphere and near the ground.④HYSPLIT backward trajectory was further verified that,the air mass transported by external sources in this pollution process came from the middle and low latitudes to the west of Yunnan,the pollutant concentration was consistent with the air mass movement path and weather system.