The eddy covariance (EC) technique-based observation system allows for researchers to determine latent and sensible heat fluxes, which are key components of the surface energy balance. The number of water and energy flux studies in Asia has increased as the number of flux measurement sites and the length of the observation periods have grown. To retrace the footprints of the AsiaFlux network and predict future research directions, we reviewed the progress in water and energy flux studies in Asia from the 1990s to the present day. This included studies on continuous evapotranspiration (ET) and surface energy balance measurements in various ecosystems, from the tropics to the polar regions. We also reviewed comparative experiments between the EC technique and other observation techniques including the use of a lysimeter or scintillometer, data processing techniques, connections between carbon and water fluxes, and multi-site syntheses. This paper discusses three remaining challenges that are hindering the derivation of scientific knowledge for ET and the surface energy balance, namely: the non-closure of the surface energy budget, imperfect compatibility between open- and closed-path gas analyzers, and difficulty in partitioning ET into evaporation and transpiration. If we leverage the advantages of the EC technique (i.e., high sampling rates of ≥ 10 Hz and continuous measurement capabilities), standardized methods for correcting and partitioning can be developed in the near future.

中文翻译：

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亚洲水和能量通量研究的进展：以涡流协方差测量为重点的综述

基于涡旋协方差（EC）技术的观测系统使研究人员能够确定潜热通量和显热通量，这是表面能平衡的关键组成部分。随着流量测量站点的数量和观测期的增加，亚洲对水和能量通量的研究数量也有所增加。为了追溯AsiaFlux网络的足迹并预测未来的研究方向，我们回顾了1990年代至今的亚洲水和能量通量研究的进展。这包括从热带到极地地区各种生态系统中持续蒸散量（ET）和表面能平衡测量的研究。我们还回顾了EC技术与其他观察技术之间的对比实验，包括使用溶渗仪或闪烁仪，数据处理技术，碳和水通量之间的联系以及多位合成。本文讨论了三个尚存的挑战，这些挑战阻碍了ET的科学知识的推导和地表能量平衡，即：未关闭地表能量收支，开放式和封闭式气体分析仪之间的兼容性不完善以及分配困难ET转化为蒸发和蒸腾作用。如果我们利用EC技术的优势（即，≥10 Hz的高采样率和连续测量功能），则可以在不久的将来开发出用于校正和划分的标准化方法。本文讨论了三个尚存的挑战，这些挑战阻碍了ET的科学知识的推导和地表能量平衡，即：未关闭地表能量收支，开放式和封闭式气体分析仪之间的兼容性不完善以及分配困难ET转化为蒸发和蒸腾作用。如果我们利用EC技术的优势（即，≥10 Hz的高采样率和连续测量功能），则可以在不久的将来开发出用于校正和划分的标准化方法。本文讨论了三个尚存的挑战，这些挑战阻碍了ET的科学知识的推导和地表能量平衡，即：未关闭地表能量收支，开放式和封闭式气体分析仪之间的兼容性不完善以及分配困难ET转化为蒸发和蒸腾作用。如果我们利用EC技术的优势（即，≥10 Hz的高采样率和连续测量功能），则可以在不久的将来开发出用于校正和划分的标准化方法。