土壤表面蒸发阻力模型与田间测定方法

SOIL SURFACE RESISTANCE MODELS TO EVAPORATION AND FIELD MEASUREMENTS

土壤表面蒸发阻力是计算土壤蒸发率的关键参数。本文讨论土壤表面蒸发阻力的概念，一层、二层理论模型与经验模型，并以在澳大利亚进行的田间测定为例，说明田间测定与计算方法。并以计算沟中的蒸发率为例，介绍其应用方法。

Surface resistance to soil evaporation r s plays an important role in land surface energy models. The order of aerodynamic resistance is 10 1 and the r s is 10 0 to 10 3 and even more as the surface from saturation to air dry. Evaporation model is more sensitive to r s than r a. Onelayer, twolayer theoretical models and an experimental model of soil surface resistance to evaporation are discussed and the field measurements in Western Australia for tillage research are presented to introduce the field measurement method. The onelayer's model considers the resistance resulted from vapor diffusion from water surface to land surface through the gradually increased top dry soil layer and maybe estimted by:r s=z(t)/D vwhere z(t) is the depth of evaporation surface in the soil and D v is vapor diffusivity in dry soil. The two layer's model adds additional resistance from vapor cross waterair interface. It is difficult to model such complex processes and a simple experimental model is used for tillage research:r s=aθ sθ 1 bwhere a is the diffusive resistance across waterair interface and b is the fitted parameter with measured r s data. The r s field measurement method with small lysimeters and calculating methods are introduced and the application of r s to estimate evaporation from ridge and furrows for tillage research are presented in the paper. The model is also used for regional water balance modeling.