空气动力学阻抗算法在半干旱区的应用比较和遥感反演

Application of Aerodynamic Resistance Arithmetic in Semi-Arid Region of China and Retrival from Remote Sensing

结合2005年中国西北半干旱区定西试验站的观测资料,使用9种空气动力学方法,估算了阻抗和感热通量,并与涡动相关阻抗结果进行了对比,分析了5～9月涡度相关测得阻抗的平均日变化特征,结果表明:(1)由于西北干旱、半干旱区和黄土高原的稀疏植被地区在植物生长季节内存在温度高、降水少、空气干燥等特点,热量和水汽输送具有特殊性;Choudh-1、Verma-R空气动力学阻抗方法对热量和动量传输的粗糙度长度、热量和动量及水汽输送的修正函数描述得较好,空气动力学阻抗估算精度较好,由此获得的感热效果也较好,较适用于该地区。(2)风速对阻抗起主要作用;植被覆盖度增加和植被密度增大的同时也增加了热量和水汽传输的粗糙度,有助于空气动力学阻抗降低。(3)采用Choudh-1方法和遥感资料反演的阻抗效果较好。

Combined with observed data at Dingxi station in semi-arid region of China,9 kinds aerodynamic resistance arithmetic are used for estimating aerodynamics resistance,the sensible heat flux is estimated based on these resistance results,the contrasts of eddy correlation results with other arithmetic results are performed,and the seasonal variable is estimated.The conclusions are：（1） Due to higher temperature,less precipitation and lower air humidity during vegetation growing season in sparse vegetation region in Loess Plateau and semi-arid region of northwest China,heat exchange and water vapor exchange are particular and not neglected,the sensible heat flux and aerodynamic resistance arithmetic Choudh-1,Verma-R are the same with aerodynamic resistance of these region because of perfect describing of heat,momentum and water vapor exchange.（2） Aerodynamic resistance was mainly influenced not only by wind speed but also by vegetation fraction due to increasing roughness length.（3）Aerodynamic resistance is well retrieved from remote sensing by using choudh-1 arithmetic.