绿洲-沙漠复合地表条件下的局地和有效粗糙度

地表空气动力学粗糙度是研究水平非均匀条件下陆面过程的基础，文中对黑河试验区各不同下垫面上地表空气动力学粗糙度进行了估算和分析，分别得到了地表空气动力学粗糙度ｚ０ｍ的有效值和局地值，发现各不同典型下垫面的局地ｚ０ｍ值明显不同，尤其在有作物存在时，绿洲的局地ｚ０ｍ值比沙漠、戈壁的值明显要大；而对同一测站，有效空气动力学粗糙度比局地空气动力学粗糙度值明显要大，运用应力分解理论对这种差异进行了解释，认为有效空气动力学粗糙度与复合表面的总应力有关，其代表了较大水平尺度内的表面和较高障碍物的综合作用，当涉及对陆表通量参数化问题时，必须首先确定水平尺度及相应的地表粗糙度参数

THE LOCAL AND EFFECTIVE AERODYNAMIC ROUGHNESS LENGTH OF A COMPLEX LANDSCAPE OF OASIS AND DESERT

Aerodynamic roughness length z 0m is the basic parameter in research for land surface processes. In this paper, the values of aerodynamic roughness length z 0m were estimated with different surface types in experiment field of Heihe river basin. It could be found that the values of z 0m were rather different between different surfaces, ones in oasis were larger than in desert, especially during canopy growing. With measurements at different height, local and effective roughness length were obtained at same site. Effective roughness length were realistically larger than local ones due to the relationship between the horizontal extent of landscape elements and aerodynamic roughness parameters of total stress at increasing heights. It could be drawn that the horizontal scale thereby aerodynamic roughness length related to had to be determined when one concerned to the research on the parameterization on land surface processes.