二阶闭合模式在污染气象学中的某些应用

本文采用二阶闭合的湍流边界层模式,进行一系列数值试验以模拟边界层中连续线源的扩散状况。试验表明:无论在稳定的或不稳定的边界层中,高源的扩散能力都低于低源;在稳定层中,粗糙地表上的大气扩散能力高于光滑表面;在相同风速和地表净辐射情况下,粗糙表面上的大气扩散能力反而低于光滑表面;对流边界层中存在反梯度输送,因而K理论的应用受到限制。试验还表明,修正的Kazanski-Monin参数可能比Monin-Obukhov长度更能反映大气的扩散能力。

APPLICATIONS OF SECOND-ORDER CLOSURE MODEL TO AIR-POLLUTION METEOROLOGY

The second order closure model in the turbulent boundary layer is used to carry out a series of numerical experiments to simulate the behaviour of a continuous line source under different conditions such as atmospheric stability, surface roughness and height of source etc. The results of these experiments are as follows: whatever it is in either stable or unstable boundary layer the atmospheric diffusion ability from a higher source is lower than that from a lower source; in stable boundary layer the atmospheric diffusion ability over a rough surface is higher than that over a smooth one; while under the conditions of the same wind speed and the same surface net radiation the atmospheric diffusion ability over the rough surface is lower than that over smooth surface. Since the counter-gradient transfer may occur in the convective boundary layer K-theory is inadequate there. The experiments also show that the modified Kazanski-Monin parameter probably is a better index for the atmospheric diffusion ability than Monin-Obukhov length.