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• 基金项目：

• 俎铁林
• 国家气象局气象科学研究院

• 摘要：本文主要介绍昆明附近某地的一次扩散试验.结果表明,水平扩散参数对不同稳定度分辨得较好.导出的垂直扩散参数能反映出地面不同粗糙度的差别,所得最大落地点浓度点距离及稀释因子比采用P-G参数提级办法算出的结果更符合实测值,并指明平均气流的上升或下沉对落地浓度的影响不可忽视.在有风条件下,导出了扩散参数随取样时间变化的指数q值.在小风条件下,对稀释效果起主要作用的是水平风方位变化的范围及垂直气流的方向和强弱,而垂直稳定度所起的作用往往是间接的.在模式选用上,小风和静风应加以区别.静风时可忽略模式中各速度分量,小风和静风的界线约在0.6m/s左右.

• Abstract：A series of diffusion experiments was made in a mountainous region near kunming. SF8 was used as tracer, and released at 70 or 80m above ground and sampled along several points from 150m to 6km downwind. Each experimental lasted 1-2h and successive sampling was made with at an interval of 5-10min. In addition, experiments of neutral balloon were made for comparison.The results show that the diffusion parameters σy and σz depend on stability and terrain. According to the experiments and some others, sigma curves were given to correct the Pasquill-Gifford's equation for a mountainous region.Under low speed wind, the primary factor affecting the horizontal diffusion is wind velocity rather than the stability. Distribution of ground level concentration is different between calm (uless than about 0.6m/s) and low-speed winds, with only the calm wind vector vanishing in the modeling.It is also found that in the mountainous region vertical current is more important than diffusion, especially under neutral conditions.

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