Exchanging latent heat flux (LE) through evapotranspiration impacts the atmospheric thermodynamics and water cycle. The Earth System Models (ESMs) in the Coupled Model Intercomparison Project Phase6 (CMIP6) are vital to reproduce improved LE variations globally, albeit with significant uncertainties. Meanwhile, the rational attribution to regions of LE simulations is essential for informed water resources administration and climate control. This paper presents the first comprehensive evaluation of the ability of 49 ESMs to model global terrestrial LE during the 2000–2014 period based on 205 eddy covariance (EC) observations. Utilizing the Bayesian Model Averaging (BMA) method, we analyzed the spatial-temporal variation and attribution to regions of global LE during 1980–2014 by combining the top six models with EC observations. The results showed that most ESMs overestimated LE, with an average BIAS of 7.57 W‧m−2, covering −7–17 W‧m−2. Among them, the MIROC6 model evinced the highest predictive skill at various land cover types. Moreover, the BMA-based global average terrestrial LE showed low LE values in dry and cold regions of temperate and cold zones of middle and high latitudes but evidenced high LE values in hot and humid regions of low-latitude tropical zones. The inter-annual variations of the BMA-based global annual LE exhibited a significant linear increasing trend with a 0.027 W‧m−2 slope (P-value <0.05). Further attribution to regions analyses were concluded, considering that LE trends were the same as the temperature trends in the Northern Hemisphere, especially in the middle and high latitudes. These conditions are comparable to radiation in the equatorial regions, correlating substantially with precipitation in dry and semi-dry regions across Asia, Europe, and Africa. In addition, the advantages of CMIP6 ESMs on LE simulations mainly including bias, and interannual variability characteristics were also concluded compared with CMIP5 ESMs.

中文翻译：

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全球地面潜热通量的评估和模拟：利用 CMIP6 气候模型和涡流相关观测的合作工作


通过蒸散交换潜热通量 （LE） 会影响大气热力学和水循环。耦合模式比较项目第 6 阶段 （CMIP6） 中的地球系统模型 （ESM） 对于在全球范围内再现改进的 LE 变化至关重要，尽管存在很大的不确定性。同时，LE 模拟对区域的合理归因对于明智的水资源管理和气候控制至关重要。本文首次根据 205 个涡流相关 （EC） 观测数据，对 2000-2014 年期间 49 个 ESM 模拟全球地面 LE 的能力进行了全面评估。利用贝叶斯模型平均 （BMA） 方法，我们通过将前六个模型与 EC 观测相结合，分析了 1980-2014 年期间全球 LE 区域的时空变化和归因。结果表明，大多数 ESM 高估了 LE，平均偏差为 7.57 W‧m−2，覆盖 −7–17 W‧m−2。其中，MIROC6 模型在各种土地覆盖类型中表现出最高的预测能力。此外，基于 BMA 的全球平均陆地 LE 在中高纬度温带和寒冷地区的干燥和寒冷地区显示低 LE 值，但在低纬度热带地区的炎热和潮湿地区表现出较高的 LE 值。基于 BMA 的全球年低排放的年际变化呈显著线性增加趋势，斜率为 0.027 W‧m−2 （P 值 <0.05）。考虑到 LE 趋势与北半球的温度趋势相同，尤其是在中高纬度地区，进一步归因于区域分析。 这些条件与赤道地区的辐射相当，与亚洲、欧洲和非洲的干旱和半干旱地区的降水密切相关。此外，与 CMIP5 ESM 相比，CMIP6 ESM 在 LE 模拟中的优势主要包括偏差和年际变率特征。