冠层内动量和物质吸收特征的数值研究

本文设计了一冠层(CL)和大气边界层(ABL)之间物质和动量交换的耦合模式,并对CL内风速、物质随高度分布和日变化作了数值模拟.结果表明,由大尺度扩散引起冠层低层的第二个风速极大和多极值的浓度分布,CL内湍流通量和物质浓度随高度减小而迅速降低,以及CL动量减小对浓度分布的重要影响,模式都能很好地描述,模拟结果与观测事实有好的一致性.利用浓度和温度廓线相似假设,导出了质量汇的经验关系.

Numerical Study on Absorptive Characteristics both Mass and Momentum in Canopy Layer

A coupling model both mass and momentum exchange between canopy layer (CL) and atmospheric boundary layer (ABL) is developed in the paper. Diurnal variations and vertical distributions both mass and wind speed in CL are simulated with the model. The results show that the model can well describe the secondary maximum wind and multiple limits of the concentration distribution in the low CL due to the additional larger- scale diffusion, the rapid decrease of both turbulent flux and mass concentration with the decrease of height in CL, and the obvious effects of the CL momentum decrease on the concentration distribution. The simulating results are consistent with experimental data. Based on the similarity hypothesis of concentration to temperature profiles, the empirical relationship of mass sink height is derived.