上海市一次重霾污染过程的特征及成因分析  

Characteristics and formation mechanism of a serious haze episode in December 2013 in Shanghai

作　　者：张欣[1] 许建明[2] 王体健[3] 朱佳雷[3] 

机构地区：[1]上海中心气象台,上海200030 [2]上海市城市环境气象中心,上海200135 [3]南京大学大气科学学院,南京210023

出　　处：《南京大学学报（自然科学版）》2015年第3期463-472,共10页Journal of Nanjing University（Natural Science）

基　　金：中国气象局预报员专项(CMAYBY2014-022);上海市科研计划项目(14DZ1202904);公益性(气象)行业专项(GYHY201206011)

摘　　要：利用PM2.5、PM10、O3、NO2、CO 5种大气成分浓度数据、常规气象观测数据和NCEP再分析资料,结合HYSPLIT4后向轨迹模式,对2013年12月1—9日发生在上海市的一次大面积、长时间重霾污染天气过程,从大气成分浓度变化、天气形势特征及成因机制等方面进行了综合分析.研究表明,此次重霾污染期间的日空气质量指数(air quality indexs,AQI)均超过150的中度污染限值,水平能见度最低降至100m以下,首要污染物PM2.5最高小时浓度达到602.3μg·m-3,创造了上海市有PM2.5监测记录以来的历史峰值.本次过程具有较强的区域性,是一次大范围的重霾天气过程,受气象条件这一扩散大背景影响很大.相比于近十年的气象场平均态而言,此次污染时段内的高空场更不利于上升运动的发展,更加静稳的地面高压场分布为重霾污染天气的发生、发展提供了有利的气象条件,近地面稳定的大气层结和静小风,非常不利于污染物的扩散.研究还表明该污染事件与大范围秸秆集中燃烧,造成大量污染物排放有一定关系.通过后向轨迹计算分析,发现颗粒物长距离输送对区域污染产生重要影响.A heavy haze episode from 1^st to 9^th in December 2013 in Shanghai was analyzed.In this paper we reported a research of exploring the pollution characteristic and the mechanism of the haze event with emphasizing the concentrations variation of polluting components,the synoptic condition and the source of the heavy haze event.The AQIs（air quality indexs）during this haze period were all above 150 and the highest hourly PM2.5concentration was 602.3μg·m^-3,creating a new record in Shanghai,and the visibility was less than 100 mduring this period.Shanghai Cen-tral Meteorological Observatory issued a haze orange waining signal on 7：22of the December 2nd,and this is the first time in Shanghai issued a haze orange signal warning.The results show that the formation of heavy haze event was directly related to the atmospheric condition.Steady circumfluence of the atmosphere made the haze event last a long time in a large region.On the other hand,there was a weak high pressure at the surface in the area of Shanghai,therefore the atmospheric current flowed downward the area to make the upward diffusion of pollutants and turbulence was restrained.We also analysis the mean height at 500 hPa,mean sea level pressure field and sea level wind field of 1st to 9th of 1994—2013.The result shows that comparing with the 10 years average state,the pressure field during the haze episold is obviously weaker,the air pressure is lower,the pressure gradient is smaller and all these lead to a smaller ground wind speed.is not conducive to the level of pollutant diffusion.Therefore,the pollutants could not diffuse horizontally quickly.In addition,the Hysplit4 trajectory model indicated that the source of the pollutants in Shanghai was from Hubei,Jiangsu and Anhui provinces,and at the same time,the MODIS instrument aboard the Terra and Aqua satellites observed many fire dots in these areas before the haze.Therefore,and the burning of straw in east China could be one reason for the heavy haze episode.

关 键 词：大气污染 霾 气象条件 轨迹分析 

分 类 号：X511[环境科学与工程—环境工程] TP79[自动化与计算机技术—检测技术与自动化装置]