西北地区典型下垫面空气动力学阻抗估算方法改进及其验证

利用2010年古浪近地层野外观测试验取得的干旱区典型下垫面（荒滩、沙漠和农田）的观测资料，对常用的3种空气动力学阻抗算法——Verma—R算法、Liu算法、Thom算法进行了适用性检验，并通过分离Thom算法中的动量和热量粗糙度对其进行改进（下称Thom-2算法）。对比不同下垫面空气动力学阻抗估算结果发现：在沙漠和荒滩下垫面，动力因素较热力因素影响大，空气动力学阻抗与风速的指数关系较农田下垫面明显；与其他3种算法相比，考虑了热量粗糙度的Thom-2算法在各种典型下垫面上的估算结果与观测值相比偏差最小，且在较为均匀的荒滩和沙漠下垫面上估算的空气动力学阻抗精度较农田高；通过比较4种算法估算干旱区不同典型下垫面空气动力学阻抗结果，说明干旱区空气动力学阻抗的估算应考虑热力粗糙度的影响。

Improvement and Validation of Aerodynamic Resistance About the Typical Underlying Surface in Northwest of China

Based on the observed data of typical underlying surface （named as wasteland, desert and cropland, respectively） of the Gu- lang Heterogeneous Underlying Surface Layer Experiment （GHUSLE） in 2010, the applicability of three aerodynamic resistance algo, rithms （Verma - R algorithm, Liu algorithm and Thorn algorithm, respectively） that used commonly was verified, and a modified algo- rithm was developed （named as Thom- 2 algorithm in this paper）, in which the momentum and heat roughness were separated by fur- ther thinking about the influence of the heat and momentum roughness in the Thom algorithm. Compared the estimated aerodynamic re- sistance of the different underlying surfaces by using the four algorithms, the dynamic factor was more important on wasteland and des- ert than thermodynamic factor about influence of aerodynamic resistance, and the exponentially relationship between aerodynamic resist- ance and wind speed was obviously better on wasteland and desert than that of cropland underlying surface. Compared with the observed data, the modified algorithm was the best one among the four algorithms for aerodynamic resistance estimating on the all typical underly- ing surfaces, and the result of modified algorithm had higher accuracy on the wasteland and desert underlying surfaces where were more uniform than that of cropland underlying surfaces. By comparing the result of the four algorithms on the three typical underlying sur- faces, the influence of heat roughness should be considered for the aerodynamic resistance estimating in arid areas.