Remote sensing has become a data source long ago for estimating evapotranspiration (ET), but often with a dilemma between temporal and spatial resolution. The recent ECOsystem Spaceborne Thermal Radiometer Experiment on Space Station (ECOSTRESS) reaches a satisfactory compromise. It provides 70 m spatial resolution and an average 4-day revisit cycle at different times of a day, making granular analysis of ET in diurnal changes and field-scale a reality. In this study, we assessed one instantaneous ET and two daily ECOSTRESS ET products (ECO3ETPTJPL & ECO3ETALEXI) at site scale, using 31 AmeriFlux towers in six regions spanning the continental US, during the period from July 2018 to September 2021. Assuming that eddy covariance sites within a region share similar climate features, we evaluated the capacity of ECOTSRESS to quantify the ET over heterogeneous landscapes. Generally, DisALEXI-JPL daily ET (R² = 0.45) have stronger correlations with in-situ ET than both PT-JPL instantaneous ET (R² = 0.23) and daily ET (R² = 0.11), while they all tend to overestimate ET in most regions. The diurnal cycles of PT-JPL instantaneous ET and seasonal cycles of two daily ET were visualized site by site; all can show temporal variations of ET. Comparing ECOSTRESS ET across and within the six regions, we found that ECOSTRESS ET accuracy varies by region, regardless of their biomes. Understanding the mechanisms controlling ET and how different data sets are able to capture ET is essential for assessing how land cover changes and human-induced disturbances influence plant water use and stress. In this regard, our study provides a deep evaluation of ECOSTRESS ET, paving the ground for future studies aiming to describe ET across heterogeneous landscapes at a finer scale.

遥感在很久以前就已成为估计蒸散量 (ET) 的数据源，但通常在时间和空间分辨率之间存在两难选择。最近的 ECOsystem 空间站星载热辐射计实验 (ECOSTRESS) 达到了令人满意的折衷方案。它提供 70 m 的空间分辨率和一天中不同时间的平均 4 天重访周期，使对昼夜变化和田间尺度的 ET 进行精细分析成为现实。在这项研究中，我们在 2018 年 7 月至 2021 年 9 月期间使用横跨美国大陆的六个地区的 31 座 AmeriFlux 塔，在场地规模上评估了一个瞬时 ET 和两个每日 ECOSTRESS ET 产品（ECO3ETPTJPL 和 ECO3ETALEXI）。假设涡度协方差一个区域内的地点具有相似的气候特征，我们评估了 ECOTSRESS 在异质景观上量化 ET 的能力。通常，DisALEXI-JPL 每日 ET (R²  = 0.45) 与原位 ET 的相关性强于 PT-JPL 瞬时 ET (R ²  = 0.23) 和每日 ET (R ² = 0.11），而他们都倾向于高估大多数地区的 ET。PT-JPL 瞬时 ET 的昼夜循环和每日两次 ET 的季节循环逐点可视化；都可以显示 ET 的时间变化。比较六个地区和六个地区内的 ECOSTRESS ET，我们发现 ECOSTRESS ET 的准确性因地区而异，无论其生物群落如何。了解控制 ET 的机制以及不同数据集如何捕获 ET 对于评估土地覆盖变化和人为干扰如何影响植物用水和压力至关重要。在这方面，我们的研究对 ECOSTRESS ET 进行了深入评估，为未来的研究奠定了基础，旨在以更精细的规模描述异质景观中的 ET。