内蒙古奈曼流动沙丘下垫面湍流输送特征初步研究

分析了2000年7月21日～8月10日在内蒙古奈曼流动沙丘下垫面取得的近地面层湍流及辐射观测资料,讨论了无量纲湍流方差与稳定度参数z/L的关系,发现无量纲速度分量方差及无量纲温度、湿度脉动方差在不稳定层结下,均满足莫宁-奥布霍夫相似理论;同时还讨论近地面层能量的收支.发现流动沙丘下垫面感热通量与地表热通量最大值分别为170 W m-2及100 W m-2;潜热通量通常小于50 W m-2;流动沙丘净辐射最大值为400 W m-2左右.(Hs+Hl),与(Rn-G)的比值在晴天白天平均值为0.78左右,流动沙丘下垫面近地面层能量不平衡现象存在,其原因有待进一步研究.

The Turbulent Characteristics in the Surface Layer over Dune at Naiman in Inner Mongolia

The turbulent and radiation data obtained over dune in Naiman from July 21 to August 10, 2000 have been analyzed. It has been discussed the relation between the non-dimensional turbulent variances and the stability parameter z/L. The result shows that the changes of the non-dimensional velocity components, temperature, and humidity variances with the stability in the surface layer under unstable stratification satisfy the Monin-Obukhov similarity theory. The energy budget in the surface layer over the movable dune has been studied also. The maximum sensible heat flux is 170 W m -2. The maximum soil heat flux in the surface layer is 100 W m -2. The maximum net radiation flux is 400 W m -2. The latent heat flux is always smaller than 50 W m -2. The average ratio between (H s+H l) and (R n-G) is 0.78 in the daytime during clear day. The energy imbalance has been found in the surface over the movable dune. The reason why the energy imbalance appears over heterogeneous surface needs to be studied more carefully in the next.