中文摘要：

本研究利用NOAH陆面过程模型模拟了1986年-1996年,2000年-2008年两个时间段内的中国大陆地区地表水热过程参数的变化。按中国大陆的六大分区（东北、华北、华东、中南、西北和西南）,分析了1986年以来这六大区域的地表蒸散的时空变化特征,并利用1980年,1995年,2000年和2005年四期土地利用/覆盖变化数据、地表反照率数据、降雨数据及地表温度和土壤水分的模拟结果,分析了近20年来中国地表蒸散的时空变化特征及其原因。结果表明：华北地区年蒸散有下降趋势外,其余5个地区的年蒸散量都有所增加。增加幅度最大的地区依次为中南,西南,华东,东北和西北。地表温度与地表蒸散间有较好的响应关系,华北地区中部和山东半岛蒸散量下降趋势较明显,地表温度呈明显增加趋势;西南地区南部蒸散量增加趋势十分明显,地表温度呈现的下降趋势也十分明显。降雨的变化趋势与表层土壤水分的变化趋势有较好的一致性,说明降雨还是影响表层土壤水分的关键因子。除东北地区外,年降雨量与年蒸散的趋势也很一致,说明这些地区降雨量仍是决定蒸散的最主要因素。

英文摘要：

In this study, water balance components and surface energy balance components during the period of 1986 and 1996, and 2000 and 2008 were estimated using NOAH land surface model. NCEP （National Centers for Environment Prediction） reanalysis forcing data, land/sea mask data from UMD （University of Maryland ）, soil properties from FAO （Food and Agriculture Organization）, vegetation properties from GSWP-2 （Global Soil Wetness Project-2） and land cover data from Data Sharing Infrastructure of Earth System Science were used to drive the NOAH model. Besides, the spatial-temporal variations of evapotranspiration in the six regions of Chinese mainland were analyzed Evapotranspiration estimates using evapotranspiration measurements from eddy covariance system in 3 stations of Yucheng, Xilinhaote and Changbaishan are validated. The correlation coefficients of 0.68, 0.91 and 0.91 are obtained for the three stations, respectively, which means that evapotranspiration estimates from NOAH model are reliable. The effects of land cover/change, surface albedo, precipitation, surface temperature and soil moisture on surface evapotranspiration were also studied. The results show that： 1） A decrease of total annual evapotranspiration over the northern China was found and an increased in of it over the central south China, the southwestern China and, the eastern China was found, respectively. No obvious changes of evapotranspiration were found in the northeastern and the northwestern China; 2） For the precipitation of the northeastern and northern China a decrease was found, while an increases is found in the central south China, the southwestern China, the eastern China and the northwestern China; 3） In the regions where evapotranspiration significantly decreases, such as in the central part of northern China and Shandong Peninsula, surface temperature has obvious increase. Similarly, there is large decrease in surface temperature and large increase in evapotranspiration in southwestern China; 4） There is goo