摘要
使用高分辨监测资料对2013年12月18-25日西安严重污染天气气象条件及影响因素进行分析。结果表明:严重污染期间,亚洲大陆中高纬度500 hPa呈一槽一脊经向环流型,陕西处于地面冷高压南部均压场控制下。空气质量转好时,高空锋区明显增强,地面冷锋快速东移、南压,边界层高度增大,近地层集聚污染物显著抬升。严重污染与非污染时段气象条件差异明显。除接地逆温外,近地层不同高度存在悬浮逆温,相对湿度呈湿-干-湿垂直分布,温湿条件有利于污染加强。严重污染属于以湿霾为主的重度霾天气,日平均能见度小于1.5 km,边界层高度小于0.7 km,郊区湿霾每日持续时间平均比市区长约5 h。严重污染期间,细颗粒物浓度远高于粗颗粒物,随时间增加趋势明显。颗粒物平均浓度在午后出现峰值,可能与边界层高度偏低、关中盆地地形因素密切相关,本地地面风场日变化对污染有加重效应。
As one of the most famous historical and cultural cities, Xi＇an is located at the central part of the Guanzhong Basin, its northern and southern areas are the Loess Plateau and the Qinling Mountains, re- spectively. Increasing trend of air pollution weather disturbs Xi＇an in recent years. Based on high resolu tion observations from air quality monitor, laser radar and automatic weather stations, meteorological con ditions and impact factors of heavy air pollution process from 18 Dec to 25 Dec in 2013 are analyzed. Re sults show that during heavy air pollution process, the circulation at 500 hPa is meridional circulation pat tern including a trough and a ridge in high latitude area. Shaanxi Province is located at the front of warm ridge with weak wind, and south to the Mongolia cold high on ground. When air quality improves, the front and wind at 500 hPa increase, and ground cold front move southeast quickly. Laser radar monitoring indicates the aerosol conglomerations below 0.5 km are uplift and the boundary layer height increases sig nificantly. Heavy air pollution process leads to severe haze and its daily average visibility is less than 1.5 km. The boundary layer height is less than 0.7 km and its peak appears at about 1500 BT. Tempera ture and humidity conditions are conducive to strengthen pollution, significantly different from common periods. An inversion of temperature exists at 2～3.2 km or 0.7～1.5 km height and relative vertical hu- midity distribution is wet-dry-wet below 3.5 km. Severe haze is mainly wet haze and its daily average dura- tion in suburban is 5 hours longer than urban. Concentration of fine particle PM2.5 is much higher than that of coarse particulate defined by PM10 minus PM2.5 during heavy air pollution process. The former has obvi ous increasing trend and the latter doesn＇t change obviously with time. Concentrations of PM2.5 and PM2.5, reach peaks at 1300 BT and 2200 BT, and maintain low values from 0500 BT to 1000 BT every day. Pollu- tant concentration rises fast from 1000
出处
《应用气象学报》
CSCD
北大核心
2016年第1期35-46,共12页
Journal of Applied Meteorological Science
基金
陕西省气象局博士基金项目(2015B-2)
国家自然科学基金项目(41305121)
江苏省自然科学基金项目(BK20141481)
关键词
空气质量
气象条件
影响因素
air quality
meteorological conditions
impact factors
