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

Aerodynamic roughness length z0m is the basic parameter in research for land surface processes. In this paper, the values of aerodynamic roughness length z0m were estimated with different surface types in experiment field of Heihe river basin. It could be found that the values of z0m 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.