干旱及半干旱区土壤水热传输模式研究

本文发展了一个干旱地区土壤中水分及热量传输模式。首先从土壤孔隙内水汽运动研究入手，阐明了在土壤深层孔隙中水汽压与液面饱和值之间处在平衡态，而土壤表层则处在非平衡态，因而必要在计算表层蒸发的公式中引入必要的土壤表层阻力，才可使模式简单实用。在此基础上建立了考虑液态水及汽态水运动耦合的多层模式，并用HEIFE沙漠站的资料对模式进行了验证，结果表明此模式较好地再现土壤内及地气界面上的水热交换过程，并且也表明干旱地区土壤中水蒸汽输送对水分平衡及蒸发的计算是重要的。这种模式很易推广到气候研究的干旱土壤下垫面的模式中去。

A Water and Heat Transport Model in Arid and Semiarid Region

This paper describes a simplified model for studying transport of moisture and heat in dry soil First, it is justified that the model can be constructed based on the local equilibrium assumption for most part of the soil body In order to take into account the failure of the assumption at the ground surface, an additional soil surface resistance is introduced to calculate the evaporation from the surface Based on the above reasons, a multi layer model accounted for the coupling liquid water and vapor movement in soil is constructed The HEIFE observation data on a desert are used to evaluate the model performance A good agreement with the model prediction is obtained The numerical results indicate that the inclusion of the vapor phase transport in the drier soil is very important to water budget and evaporation estimation for arid and semiarid region The model developed here can be easily adjusted to the application of climate studies