A harmonized global land evaporation dataset from model-based products covering 1980–2017

[摘要] Land evaporation (ET) plays a crucial role in the hydrological and energy cycle. However, the widely used model-basedproducts, even though helpful, are still subject to great uncertaintiesdue to imperfect model parameterizations and forcing data. The lack ofavailable observed data has further complicated estimation. Hence, thereis an urgency to define the global proxy land ET with lower uncertaintiesfor climate-induced hydrology and energy change. This study has combinedthree existing model-based products – the fifth-generation ECMWF reanalysis(ERA5), Global Land Data Assimilation System Version 2 (GLDAS2), and thesecond Modern-Era Retrospective analysis for Research and Applications(MERRA-2) – to obtain a single framework of a long-term (1980–2017) daily ETproduct at a spatial resolution of 0.25 ∘ . Here, we use thereliability ensemble averaging (REA) method, which minimizes errors usingreference data, to combine the three products over regions with highconsistencies between the products using the coefficient of variation (CV).The Global Land Evaporation Amsterdam Model Version 3.2a (GLEAM3.2a) and fluxtower observation data were selected as the data for reference andevaluation, respectively. The results showed that the merged productperformed well over a range of vegetation cover scenarios. The mergedproduct also captured the trend of land evaporation over different areaswell, showing the significant decreasing trend in the Amazon Plain in SouthAmerica and Congo Basin in central Africa and the increasing trend in theeast of North America, west of Europe, south of Asia and north of Oceania.In addition to demonstrating a good performance, the REA method alsosuccessfully converged the models based on the reliability of the inputs.The resulting REA data can be accessed at https://doi.org/10.5281/zenodo.4595941 (Lu et al., 2021).

[学科分类] 眼科学