Abstract
The purpose of the study is to determine the daily and annual variations in the surface heat budget of the arid and semi-arid regions in China. This paper presents a heat balance model for calculating the evaporation, soil water content, soil temperature of the bare soil surface. In the model the transport of liquid water, diffusion of water vapor and vaporization in the soil pores are described. The snow accumulation and melting processes in winter season are also considered. The albedo of snow surface is considered as a function of the air temperature and the elapsed time after snowfall. Soil parameters of the hydraulic conductivity and of the matric potential are determined experimentally. The other estimated results are as follows. The annual values of the potential evaporation are 800-2700mmy-1. The thermal diffusivity of the ground is about 0.2×10-6m2s-1 for the surface layer, and about 1×10-6m2s-1 for the layer of 1.6-3.2m depth.
