【摘要】 着眼于城市冬季气溶胶扩散特征问题,针对地形复杂的兰州市及周边地区,开发了WRF模式,使之与包含了大气气溶胶辐射效应和气溶胶粒子扩散的综合大气边界层数值模式嵌套,以模拟城市冬季边界层气溶胶的扩散和分布规律。通过一个个例的模拟结果分析,揭示了兰州冬季气溶胶的扩散分布的如下特征;市区盆地内100 m以下存在东、西两个浓度高值中心,中心值为0.6~3.0 mg.m-3,往上浓度递减,1000 m高度处仅为0.02 mg.m-3。受排放源强、源高、气象场等因素的共同影响,白天盆地内气溶胶浓度随高度和时间的变化强烈,白天浓度随时间最大变化幅度为1.0 mg.m-3。气溶胶输送扩散高度可达到600~800 m,此高度以上浓度值很小。代表性测点上模拟的气溶胶浓度廓线表明,中午浓度达到最高,垂直扩散最强。这些结果与以往的烟雾层高度观测和气溶胶光学厚度观测结果吻合。夜间,盆地内气溶胶浓度随高度和时间的变化减弱,气溶胶输送扩散高度在400~500m,夜间浓度随时间变化平均幅度为0.05 mg.m-3。更多还原

【Abstract】 Focused on the diffusion properties of urban aerosol in winter,the paper develops and applies the WRF model,simulates the aerosol diffusion and distribution over urban atmospheric boundary layer in winter,through a case analysis,discusses the characters of aerosol diffusion and distribution on boundary layer structure of Lanzhou area over a complex terrain domain in winter.The model system is integrated the WRF model with the comprehensive ABL model in which the radiative effect and the diffusion of urban aerosol particles are considered.The primary character is that the aerosol has two high value centers which are under 100 m,center concentration is about 0.6～3.0 mg·m-3.The center concentration decreases upwards and only has 0.02 mg·m-3 at 1000 m.Under the joint influence of the emission source strength,source height and meteorology field,aerosol concentration varies greatly according to height and time in day time and its variation is 1.0 mg·m-3.Aerosol transmission diffusion height can reach 600～800 m in day time.The simulated aerosol concentration profiles on the representative spots demonstrate the highest concentration and the most extensive vertical diffusion range at noon.These results correspond with the former observation of the smog layer height and the turbidity.At night,aerosol concentration varies weaken according to height and time,aerosol transmission diffusion height is 400～500 m and its variation is 0.05 mg·m-3.更多还原