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中文摘要：
提出了以Priestley-Taylor方程为基础,综合利用地面气象观测数据与卫星遥感观测数据的陆面蒸散量估算方法。其基本思路是：基于地表能量平衡原理,利用遥感观测与地面气象观测数据,计算给定气温条件下全植被覆盖与祼土地面在极湿、极干状况下的地表温度,构建每个像元的地表温度（Ts）与植被指数（VI）的理论梯形空间,进而根据该象元Ts-VI坐标点在该梯形中的位置,计算其Priestley-Taylor系数,并利用Priestley-Taylor方程估算像元的蒸散比。利用美国一个半干旱地区的地面观测数据进行了精度验证,结果表明该方法具有较理想的精度,蒸散量估算的平均绝对误差约为35.5%。
英文摘要：
Land surface evapotranspiration（ET） is an important link in the process of regional water cycle.Many methods have been proposed for estimating ET utilizing information from different types of remotely sensed data,often in combination with ancillary surface and atmospheric observations.In particular,Ts-VI（surface temperature/vegetation index） triangle method using optical and thermal infrared satellite data is common for the retrieval of ET.However,Ts-VI triangle method has several major limitations,including the subjectivity of determining the dry and wet edges and the difficulty in defining the ET at the joint of dry edge and wet edge.By modifying the concept of the vegetation index-temperature（VIT） trapezoid proposed by Moran et al.（1994）,Wang et al.（2011） developed a method of constructing the trapezoidal relationship between land surface temperature（Ts） and enhanced vegetation index（EVI） using ground-based meteorological observations and satellite remotely sensed surface temperature and vegetation index data jointly based on the energy balance equation.On the basis of that,a land surface actual ET estimating method was developed in the present study by estimating Priestley-Taylor coefficient,and then ET was calculated using the Priestley-Taylor equation for each pixel.The method is composed of three major steps：1） establish Ts-VI trapezoidal space under extreme conditions,i.e.,full vegetation cover and bare soil with extreme dryness and wetness,for each pixel,based on the principle of land-surface energy balance;2） calculate the Priestley-Taylor coefficient for each pixel according to the position of the observed Ts-VI point in the trapezoid space;3） finally use the Priestley-Taylor equation to estimate actual ET of the pixel.Compared with the method of VIT trapezoid,the Ts-VI trapezoid method has the advantage of taking into account the interaction of different variables and parameters（such as the net radiation Rn,aerodynamic resistance ra,sensible heat flux density H,st
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