The spatial distribution ET in Gannan grassland was simulated with the energy balance equation and series data sets of data (MODIS and meteorological) from 2000 and 2009. At the same time, the utilization of a modified Penman-Monteith Model simulated the region’s average daily potential ET . In accordance with the 55-year temperature changes in the Northwest Arid Region of China, the region’s development tendency of remote sensing ET and potential ET were analyzed. It was concluded that the remote sensing ET ranged from 0.981 6 mm to 8.208 1 mm, with a mean value of 5.514 1 mm in 2000. Remote sensing ET ranged from 1.647 2 mm to 7.653 7 mm with a mean value of 5.565 0 mm and potential ET ranged from 1.678 9 mm to 8.248 7 mm with a mean value of 6.158 1 mm in 2009. Remote sensing ET was lower than the potential ET in general. However, remote sensing ET was higher than the potential ET in the Hezuo County, along the Taohe River and around Tieba Township. It explained that there existed a contradiction in the evaporation phenomenon, which was related to the increasing temperature trend of Northwest China. For example, the temperature of 1965, 1982and 1995 increased 6.70%, 11.69% and 7.70% higher than the average of 1957-1998. In particular, the annual temperature of 2010 increased by 57.56%, and its average temperature was 5.77 higher than the average tem- perature of 1957-1998; that is to say, temperature rapidly increased in recent years.%使用MODIS数据及相关气象数据,采用能量平衡方程,对甘南草原区域2000年、2009年7月份日均遥感ET 进行了反演,同时采用修正的Penman-Monteith模型模拟了该区域的日均潜在ET ,并根据西北干旱区55年的气温变化,分析该区域的遥感E T 和潜在E T 的发展趋势.研究表明：2000年的遥感E T为0.9816∼8.2081 mm,平均5.5141 mm.2009年的遥感E T 为1.6472∼7.6537 mm,平均5.5650 mm；而2009年潜在E T 为1.6789∼8.2487 mm,平均6.1581 mm,总体上遥感E T 比潜在E T 低.然而,在合作、洮河及铁坝乡附近,遥感ET 比潜在ET 高,说明研究区存在“蒸发悖反”现象,这与西北干旱区气温一直呈增长趋势有关.其中,1965年、1982年、1995年的气温比1957-1998年的平均气温分别增加了6.70%,11.69%,7.70%,尤其是2010年比1957-1998年的平均气温增加了57.56%,达到了5.77◦C,表明近期气温迅速升高.
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