光闪烁方法测算区域蒸散研究进展

蒸散是土壤-植物-大气连续体(SPAC)水热运移的一个重要环节,是全球水量平衡的重要组成,一直是气象学、水文学、地理学及生态学等相关学科重要的研究主题。区域尺度地表蒸散的时空变化过程十分复杂。迄今为止,在像元尺度水平上,特别在非均匀下垫面和地形起伏条件下,有代表性的进行地表蒸散的观测仍然十分困难。虽然遥感方法可获得区域尺度水平蒸散,但其主要根据经验或半经验模型对区域蒸散进行估算,模型选用的参数以及结果还需地面实测数据进行改进、优化,如何获得与遥感尺度相应的地面蒸散实测数据成为模型验证的重点和难点,光闪烁方法的出现为上述问题的解决带来了希望。光闪烁方法能够适应复杂下垫面,测量结果准确且具有时空平均等优点,成为测量区域蒸散的有效方法、验证遥感模型结果的最佳手段。从理论原理、计算方法、主要应用情况等方面,概述了光闪烁方法观测区域蒸散研究进展,指出了影响测算精度的不确定性因素,并提出了研究展望,旨在进一步推动该方法在区域蒸散观测研究中的应用,促进相关学科的发展。

Advances in the study of regional-averaged evapotranspiration using the scintillation method

Evapotranspiration is key to hydrological and heat transfer in the soil-plant-atmosphere continuum (SPAC). It is also an important component of water and energy balances, and now it is becoming an important research subject in meteorology, hydrology, ecology and other related areas. The temporal and spatial variations in surface evapotranspiration at the regional scale are very complicated, which means that it is still difficult to measure surface evapotranspiration at the kilometer scale above a heterogeneous underlying terrain. Remote sensing methods can provide regional evapotranspiration results by using an empirical or semi-empirical model, but the parameters in the models and the outputs need to be improved and optimized according to the real-time measurement results. The difficulty with model verification is how to obtain surface evapotranspiration at the kilometer scale. However, the development of the scintillometry method may be able to solve this problem. The scintillometry method can adapt to complex surfaces, and produces accurate results when both time and space are averaged. This method has become an effective way to measure regional evapotranspiration and may be the best way to verify the outputs of remote sensing models. This study discusses the background theory to the scintillometry method, summarizes the potential applications of the method, and analyzes the uncertainties in the hardware equipment, the environmental factors, and key parameters in the calculation. Finally, we put forward research prospects based on theoretical principle, the calculation method, and potential applications. Our summary and analysis can be used to promote the application of the scintillometry method in regional evapotranspiration measurements and relevant disciplines.