Terrestrial evapotranspiration (ET) is a vital process regulating the terrestrial water balance. However, significant uncertainties persist in global ET estimates. Focusing on the area between 60°, we performed an intercomparison of 90 state-of-the-art ET products from 1980 to 2014. These products were obtained from various sources or methods and were grouped into six categories: remote sensing, reanalysis, land surface models, climate models, machine learning methods, and ensemble estimates. It is shown that global ET magnitudes of categories differ considerably, with averages ranging from 518.4 to 706.3 mm yr⁻¹. Spatial patterns are generally consistent but with significant divergence in tropical rainforests. Global trends are mildly positive or negative (−0.10 to 0.37 mm yr⁻²) depending on categories but with distinct spatial variability. Evaluation against site measurements reveals various performances across land cover types; the ideal point error values range from 0.45 to 0.83, with wetlands performing the worst and open shrublands the best. Using the three-cornered hat method, there are spatial differences in ET uncertainty, with lower uncertainty for ensemble estimates, showing less than 15% relative uncertainty in most areas. The best global ET data set varies depending on the intended use and study region. Distinct spatial patterns of controlling factors across categories have been identified, with precipitation driving arid and semi-arid regions and leaf area index dominating tropical regions. It is suggested to include advancing precipitation inputs, incorporate vegetation dynamics, and employ hybrid modeling in future ET estimates. Constraining estimates using complementary data and robust theoretical frameworks can enhance credibility in ET estimation.

中文翻译：

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通过多产品比对和评估协调全球陆地蒸散量估算


陆地蒸散量（ET）是调节陆地水平衡的重要过程。然而，全球蒸散估计仍然存在重大不确定性。我们以 60° 之间的区域为重点，对 1980 年至 2014 年 90 个最先进的 ET 产品进行了比对。这些产品通过各种来源或方法获得，分为六类：遥感、再分析、土地地表模型、气候模型、机器学习方法和集合估计。结果表明，全球蒸散量的类别差异很大，平均值范围为 518.4 至 706.3 mm yr ^-1 。热带雨林的空间格局总体一致，但存在显着差异。全球趋势略有正向或负向（-0.10 至 0.37 mm yr ^-2 ），具体取决于类别，但具有明显的空间变异性。根据场地测量进行的评估揭示了不同土地覆盖类型的不同表现；理想的点误差值范围为 0.45 至 0.83，湿地表现最差，开阔灌木地表现最好。使用三角帽法，ET不确定性存在空间差异，集合估计的不确定性较低，大部分地区的相对不确定性低于15%。最佳的全球 ET 数据集因预期用途和研究区域而异。已经确定了不同类别控制因素的独特空间模式，降水驱动干旱和半干旱地区，叶面积指数主导热带地区。建议在未来的蒸散估计中纳入提前降水输入、纳入植被动态并采用混合模型。 使用补充数据和稳健的理论框架约束估计可以提高蒸散估计的可信度。