Evapotranspiration (ET) is an essential part of the hydrological cycle and accurately estimating it plays a crucial role in water resource management. Surface energy balance (SEB) models are widely used to estimate regional ET with remote sensing. The presence of horizontal advection, however, perturbs the surface energy balance system and contributes to the uncertainty of energy influxes. Thus, it is vital to consider horizontal advection when applying SEB models to estimate ET. This study proposes an innovative and simplified approach, the surface energy balance-advection (SEB-A) method, which is based on the energy balance theory and also takes into account the horizontal advection to determine ET by remote sensing. The SEB-A method considers that the actual ET consists of two parts: the local ET that is regulated by the energy balance system and the exotic ET that arises from horizontal advection. To evaluate the SEB-A method, it was applied to the middle region of the Heihe River in China. Instantaneous ET for three days were acquired and assessed with ET measurements from eddy covariance (EC) systems. The results demonstrated that the ET estimates had a high accuracy, with a correlation coefficient (R 2 ) of 0.713, a mean average error (MAE) of 39.3 W/m 2 and a root mean square error (RMSE) of 54.6 W/m 2 between the estimates and corresponding measurements. Percent error was calculated to more rigorously assess the accuracy of these estimates, and it ranged from 0% to 35%, with over 80% of the locations within a 20% error. To better understand the SEB-A method, the relationship between the ET estimates and land use types was analyzed, and the results indicated that the ET estimates had spatial distributions that correlated with vegetation patterns and could well demonstrate the ET differences caused by different land use types. The sensitivity analysis suggested that the SEB-A method requested accurate estimation of the available energy, R n ? G , but was less constrained with the difference between ground and air temperature, T 0 ? T a – l o c .
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机译：蒸散量（ET）是水文循环的重要组成部分，准确估算它在水资源管理中起着至关重要的作用。表面能平衡（SEB）模型被广泛用于通过遥感估算区域ET。但是，水平对流的存在会扰动地表能量平衡系统，并导致能量涌入的不确定性。因此，在应用SEB模型估算ET时考虑水平对流至关重要。这项研究提出了一种创新且简化的方法，即表面能平衡平流（SEB-A）方法，该方法基于能量平衡理论，并考虑了水平对流以通过遥感确定ET。 SEB-A方法认为实际ET由两部分组成：由能量平衡系统调节的局部ET和由水平对流产生的奇异ET。为了评估SEB-A方法，将其应用于中国黑河中部地区。获取了三天的瞬时ET，并通过涡度协方差（EC）系统的ET测量进行了评估。结果表明，ET估计具有较高的准确性，相关系数（R 2）为0.713，平均平均误差（MAE）为39.3 W / m 2，均方根误差（RMSE）为54.6 W / m 2在估计和相应的度量之间。计算百分比误差以更严格地评估这些估计的准确性，其范围从0％到35％，超过80％的位置误差在20％以内。为了更好地理解SEB-A方法，分析了ET估计值与土地利用类型之间的关系，结果表明ET估计值具有与植被格局相关的空间分布，可以很好地说明不同土地利用方式引起的ET差异。类型。敏感性分析表明，SEB-A方法要求准确估计可用能量R n？。 G，但受地面温度和气温T 0？的限制较小。 T a – l o c。
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