摘要
通过改进Prandtl混合长理论,得出近地层风廓线形式u/z为u*/k1z其中k1:(σw/u*)(1-k/2);在中性层结下k1为0.4,风廓线与传统形式完全相同。分析认为Karman常数与垂直湍流强度有关,其量值的弱不确定性是由于“中性”及“近地层常通量假定”不符合实际大气情况所致;所建立的垂直湍流强度与无量纲风廓线关系可以合理地描述在稳定边界层的情况。
A new expression formula of logarithmic wind profile in the form of u k 1z for uz , where k 1 is σ wu *(1-k/2), is derived by improving the Prandtl mixing length theory. The expression is absolutely the same as classical logarithmic wind profiles in a neutral atmosphere, and from which the analysis shows that the Karman constant is related to the vertical turbulence intensity, and implies that the Karman constant is 0.4 in a neutral stratified layer only, and its uncertainty in field experiments may be mainly caused by thermodynamical effects of the surface layer atmosphere even though in a near neutrally stratified atmosphere. Furthermore the expression of the vertical turbulence intensity given in the paper can bring about more reasonable results in a stable stratified surface layer atmosphere.
关键词
近地层
风廓线
湍流
湍流强度
混含长
logarithmic wind profile
Karman constant
vertical turbulence intensity
mixing length
