西昌市环境空气质量气象影响因素的分析研究

Study on the Effect of Meteorological Factors on Ambient Air Quality in Xichang

利用西昌市2012—2014年气象资料和空气质量资料,采用统计学方法对西昌市气候背景、地面和高空风场特征、污染系数、大气稳定度,风速、风向、稳定度联合频率进行分析,结果表明:全年的大气稳定度均以中性为主,不影响空气团做垂直方向运动,对大气污染物的扩散无明显影响;西昌市全年污染系数均以偏北风(以N和NNW为主)最大,偏南风(以SSW为主)次之,偏西风和偏北风最小,西昌市出现空气质量时好时坏的现象;整个冬季地面静风频率较高,达82%~85.4%,地面主导风向以偏南风和偏北风为主,各高度上风速最大值均出现在SSW方向上,各层风速均随高度增加而增大;地面静风是造成西昌市污染的主要原因,地面静风频率大时污染率越大,空气质量越差;由于污染源的位置关系,地面主导风向为偏南风时也是造成污染的重要原因,并以此为相关部门提出建议。

With the meteorological data and air quality data from 2012 to 2014 in Xichang, we adopt statistical methods to analyze the climatic background, the surface wind field and upper wind field characteristics, the pollution coefficient, the atmospheric stability, the combined frequency of wind direction, speed and stability in Xichang. The results show that the annual atmospheric stability remains neutral mostly, which does not affect the vertical movement of air mass, and has no obvious influence on the diffusion of atmospheric pollutants. The pollution coefficient in Xichang is the highest in the northerly winds (mainly N and NNW), second in the southerly winds (mainly SSW), and lowest in the westerly and easterly winds during the year. So the air quality in Xichang alters between good and poor. The frequency of surface static wind remains high throughout the winter, reaching 82% to 85.4%, and the dominant surface wind direction is mostly southerly and northerly. The maximum wind speeds at all heights occurs in the SSW direction, and the wind speed at each height increases with increasing height. Surface static wind is the major factor contributing to the pollution in Xichang. The greater the surface static wind frequency, the greater the pollution rate, and the worse the air quality. Because of the location of the pollution source, the dominant southerly surface wind is also an important cause for pollution. The results of our study can be recommended to relevant government departments.