Abstract: By using the one dimensional soil-vegetation-atmosphere coupled numerical model the processes of land surface evapotranspiration for the difference vegetation cover factor in the arid and semi-arid region of Northwest China (around 38N, 105E) are studied. The evapotranspiration process and the soil moisture content in the soil-vegetation-atmosphere system is simulated and compared between simulated and observed the soil moisture content for different vegetation shielding factor. The results indicate that the evapotranspiration can be divided into three stages in accordance with the variations of the soil moisture near the surface, and brought to light the each other transition processes of the heat balance components at the underlying surface. The preliminary results of the numerical simulation indicate that the soil properties and vegetation shielding factor are the most important influence factor in this process, and the land surface process model is capable of predicting the thermal and evapotranspiration processes and siutable to climate study.

Key words: the soil-vegetation-atmosphere continuum, the evapotranspiration process, the land surface process model

摘要： 利用-维土壤-植被-大气耦合数值模式，研究了我国西北(37.5N, 105E)干旱半干旱地区夏季不同植被覆盖度近地面层的水分蒸散过程。模式较好地再现了蒸散过程三阶段的变化趋势特征。模式还揭示了蒸散过程中，下垫面热量平衡分量间的相互转换过程，并由实测资料对模拟结果进行了检验。

关键词: 土壤-植被-大气连续体, 蒸散过程, 陆面过程模式