玉米农田空气动力学参数动态及其与影响因子的关系

对锦州玉米农田生态系统生长季内的粗糙度(z₀)和零平面位移(d)动态特征及其与风速、株高(h)和叶面积指数(LAI)的关系分析表明:零平面位移(d)在玉米拔节后10d左右,株高约1.40m时开始出现,在抽雄前为0.80-1.00m,抽雄后为1.00-1.40m;z₀在抽雄前小于0.20m,乳熟前后达到最大,约为0.40m。d/h和z₀/h分别为0.40-0.54和0.10-0.14,在h达到最大值前,分别随LAI增大而减小和增大。d出现前,z₀与风速呈负指数关系,与LAI和h都呈线性关系。d出现后,风速与z₀、d之和的关系比与各自的关系更显著;d与LAI、h都呈显著指数正相关关系,LAI、h对z₀的影响大于d和z₀+d,且h的作用大于LAI。d出现至h达到最大期间,上述各种关系最为显著。研究结果可为建立空气动力学参数的动态参数化方案及改进陆面过程模型提供依据。

Dynamics of aerodynamic parameters over a rainfed maize agroecosystem and their relationships with controlling factors

Based on continuous observation data of 16 m gradient weather observation tower from 2006 to 2008 at Jinzhou agricultural ecosystem research station, dynamic characteristics of aerodynamic parameters roughness (z₀) and zero-plane displacement(d) over a rainfed maize agroecosystem and their relationships with controlling factors during growing seasons are analyzed. The results showed that d appears about 10 days after jointing when plant height (h) is about 1.40 m and increases from 0.80-1.00 m to 1.00-1.40 m after tasseling stage. z₀ is smaller than 0.20 m before tasseling stage and comes to the maximum about 0.4m before and after milk stage. d/h and z₀/h are 0.40-0.54 and 0.10-0.14, and are decreasing and increasing with LAI, respectively, before h comes to the maximum. Before d appears, negative exponent and positive linear relationships between z₀ and wind speed at 2 m (u₂), z₀ and LAI or h are found. Yet, after d appears, relationship between u₂ and z₀+d is more notable than those between u₂ and z₀ or d. At the same time, positive exponent relationships between z₀ or d and LAI or h respectively are found. LAI and h influence more to z₀ than to d and z₀+d with greater role for the latter. Those relationships are more conspicuous from d appearing to h coming to the maximum. These research conclusions will play an important reference role for setting up aerodynamic parameterization and improving land surface process model.