The eddy covariance method estimates the energy flux of latent heat for evapotranspiration. However, imbalance between the land surface energy output and input is a well‐known fact. Energy balance closure is most commonly not achieved, and therefore the eddy covariance method potentially underestimates actual evapotranspiration. Notwithstanding, the method is one of the most established measurement techniques for estimating evapotranspiration. Here, evapotranspiration from eddy covariance (ET_EC) is cross‐checked with evapotranspiration calculated as the residual of the water balance (ET_wb). The water balance closure using ET_EC is simultaneously validated. Over a 6‐yr period, all major terms of the water balance are measured including precipitation, recharge from percolation lysimeters, and soil moisture content from a cosmic‐ray neutron sensor, a capacitance sensor network, and time domain reflectometry (TDR), respectively. In addition, we estimate their respective uncertainties. The study demonstrates that both monthly and yearly ET_EC and ET_wb compare well and that the water balance is closed when ET_EC is used. Concurrently, incoming available energy (net radiation minus ground heat flux) on average exceeds the turbulent energy fluxes (latent heat flux and sensible heat flux) by 31%, exposing the energy–surface imbalance. Consequently, the imbalance in the energy balance using the eddy covariance method must, to a lesser degree, be caused by errors in the latent heat estimates but can mainly be attributed to errors in the other energy flux components.

中文翻译：

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利用水平衡和涡度协方差方法比较蒸发蒸腾量

涡度协方差法估算了蒸散的潜热能量通量。但是，陆地表面能量输出和输入之间的不平衡是众所周知的事实。能量平衡的关闭通常是无法实现的，因此，涡度协方差方法可能会低估实际的蒸散量。尽管如此，该方法还是用于估计蒸散量的最成熟的测量技术之一。在此，将涡流协方差（ET _EC）的蒸散量与计算为水平衡剩余量（ET _wb）的蒸散量进行交叉检查。使用ET _EC关闭水平衡同时验证。在6年的时间段内，对水平衡的所有主要术语进行了测量，包括降水，渗滤溶渗仪的补给，以及宇宙射线中子传感器，电容传感器网络和时域反射仪（TDR）的土壤水分含量。 。另外，我们估计它们各自的不确定性。研究表明，每月和每年的ET _EC和ET _wb都比较好，并且当ET _EC时水平衡是关闭的用来。同时，进入的可用能量（净辐射减去地面热通量）平均比湍流能量通量（潜热通量和显热通量）高出31％，暴露了能量-表面不平衡。因此，使用涡度协方差方法的能量平衡失衡必须在较小程度上由潜热估算中的误差引起，但主要可以归因于其他能量通量分量中的误差。