农田植被层上方湍流通量输送特征分析

ANALYSIS OF TRANSFER CHARACTERISTICS OF TURBULENT FLUX OVER CANOPY OF FIELD CROPS

根据农田植被层上方的温湿风梯度观测资料，采用基于莫宁－奥布霍夫相似理论的廓线梯度法计算了农田植被层上方的湍流通量，进而确定出拖曳系数、斯坦顿数和道尔顿数。文中检验了用于农田植被层上方湍流通量计算的普适函数的适用性，讨论了湍流通量以及拖曳系数等随稳定度参数、粗糙高度、平均风速等因子的变化规律。结果表明，农田植被层上方的湍流通量随层结稳定度的变化而变化；拖曳系数、斯坦顿数和道尔顿数也不是常数，而是层结稳定度、粗糙高度和平均风速的函数。

In this paper,turbulent flux over canopy of field crops was calculated using Profile Gradient Method derived from Monin Obhov Similarity Theory and drag coefficient,Stanton number and Dalton number were also further defined.The applicability of universal function which was used for turbulent flux calculation was examined and whether or not the flux and drag coefficient varied with atmospheric stratification stability,roughness length and average wind speed was discussed.Results of the study indicate that the flux depends on the stability and the drag coefficient,the Stanton number or the Dolton number is pertain to the stability,roughness length and average wind speed respectively.