The improvement and validation of the model for retrieving the effective roughness length on TM pixel scale

In the micrometeorolotrical and microclimatic research fields, surface roughness length is one of the very important surface parameters in estimating surface fluxes. With the development of remote sensing models for retrieving surface fluxes, the concept and estimating method for surface roughness length has been developed correspondingly. This paper analyzed researcher's cognition process of the surface roughness length. An experiment was further carried out in 2004 to improve and validate Zhang's model, which was proposed in 2004. In this paper, roughness elements' geometric roughness length was retrieved on TM pixel scale, and aerodynamic surface roughness length under conditions of atmospheric stability was iterated out with field measured data. By choosing eight typical wind directions, we established a relationship between roughness elements' geometric roughness length and effective surface roughness length, which made quite an improvement for Zhang's model. The parameters of the model were optimized and more universal, and the model could be used universally. The result indicates further that effective roughness length of a certain g fetch is related closely to equivalent geometric roughness length of each pixel unit within the fetch area. The model for retrieving surface roughness length would help to improve the surface fluxes retrieval precision greatly