近11年兰州空气污染特征及其边界层结构影响的分析

Analysis of the characteristics of air pollution and its boundary layer structural effect in recent 11 years over Lanzhou

利用来自环保部门的空气污染资料,分析了近11年兰州市空气污染特征;结合气象地面和探空观测资料,分析了山谷地形条件下大气边界层结构对兰州空气污染的影响.结果是兰州近11年的空气污染有整体减轻趋势,但污染仍很严重,空气质量大多年份都达不到国家二级水平,污染物主要为可吸入颗粒物.严重污染时期集中在秋末、冬季和春季,秋冬季空气污染较稳定,主要受可高达1000 m的深厚稳定边界层影响,而春季空气污染指数标准偏差较大.11年空气污染指数的月平均次高峰出现在3月,相对以往研究提前了1个月.

The characteristics of air pollution in Lanzhou in the past 11 years were analyzed by using air pollution observations from the environmental protection department concerned.Combined with the meteorological data,such as the surface observations and the sounding data,the effect of the atmospheric boundary layer on air pollution was investigated under the valley terrain conditions.The results show that air pollution has been reduced in recent 11 years but the situation is still severe.The air quality could not meet the nationalⅡlevel in the most years.The main air pollutant is respirable suspended particulate.The heavy air pollution periods are distributed in late autumn,winter and spring.Especially,heavy air pollution in winter,which has appeared to be in a stable condition,is mainly influenced by the highly stable boundary layer which is at a height of nearly 1 000 m.In the spring,the standard deviation of the air pollution index is larger than the other seasons.The second peak of the monthly average of the air pollution index is found in March.Compared with the previous research,this study has found that it has advanced by 1 month.