烟羽在夜间雾天状况下的扩散数值研究

用夜间雾的数值模式研究了高架源在雾形成前后的扩散特征。模拟结果表明，雾的出现影响了大气近地层结，使原来很稳定的大气变成不稳定大气，但雾顶以上仍是逆温状态，这样导致雾顶附近的高浓度污染物向地面输送加剧，造成地面污染。这种情况非常类似于日出后出现的地面熏烟。研究结果从大气扩散方面解释了近年来在雾天临测中发现的地面高浓度污染现象，说明雾天是造成地面严重污染的重要天气之一。

NUMERICAL MODELING OF PLUME DISPERSION ON FOG CONDITIONS

An one-dimensional fog model together with a pollutant diffusion model to investigatethe effects of fog cover on dispersion of pollutants has been performed.The output results ofthe fog model are utilized as field input field of diffusion model,and dispersion of an elevatedstack plume is calculated on such field.The simulation indicates that the variation in stabilitystructure and diffusion field during fog event is responsible for the rising of concentration ofpollutans at the surface. The effects of mixing layer within fog cover are similar to those de-veloped during sun rise and may also result in fumigation or severe air pollution episode.