Evapotranspiration Retrieval Under Different Aridity Conditions Over North American Grasslands

文献类型： 外文期刊

第一作者： Liao, Qian-Yu

作者： Liao, Qian-Yu;Leng, Pei;Li, Zhao-Liang;Gao, Mao-Fang;Duan, Si-Bo;Liao, Qian-Yu;Ren, Chao;Zhang, Xia;Shang, Guo-Fei

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关键词： Vegetation mapping; Soil moisture; Satellites; Remote sensing; Moisture; Land surface; AmeriFlux; aridity conditions; evapotranspiration (ET); soil-moisture variation; water-stress

期刊名称：IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING （ 影响因子：5.6； 五年影响因子：6.086 ）

ISSN： 0196-2892

年卷期： 2020 年 58 卷 10 期

页码：

收录情况： SCI

摘要： Evapotranspiration (ET) is one of the most critical parameters in water- and energy-related domains. Two basic assumptions with respect to soil-moisture variation have been widely investigated for the retrieval of ET based on the trapezoid methods. Specifically, soil moisture within the surface and root-zone layers was assumed to vary synchronously in most of the earlier analyses. However, several recent investigations assumed that soil moisture within the upper soil layer should be dried up before the root-zone layer is stressed. To this end, the retrieval of ET under different aridity conditions over North American grasslands was investigated with the two assumptions, and the estimated ET was assessed using the flux data collected from eight AmeriFlux sites. Based on the available data from 2002 to 2018, results showed that the asynchronous-assumed method can obtain better ET estimates than the synchronous-assumed method over semiarid and subhumid areas, whereas the synchronous-assumed method can obtain better ET estimates in humid areas. Moreover, because of the different closure techniques used for the ET correction, no consistent conclusions could be found for the arid conditions to determine which trapezoid was better. Specifically, it was found that the cases of surface soil with zero water availability that were defined by the asynchronous-assumed trapezoid method rarely occur, even in arid areas, which indicated that the critical boundary that determines whether the root-zone layer begins to be water-stressed may need to be redefined.

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