Institute of Tibetan Plateau Research, Chinese Academy of Sciences
因为基于卫星遥感和地面观测开发出的不同时空分辨率蒸散发(ET)产品在青藏高原(TP)仍存在不确定性,从而限制了这些产品在水文气象和气候评估方面的应用。本文基于涡动观测的ET对六种ET (PML、EB-ET_V2、GLEAM、GLDAS、ERA5_Land和MOD16)产品进行评估并比较各产品之间的差异,对TP区域ET产品不确定性做了分析。结果表明: (1)观测值与对应像元ET值之间存在较好的相关性、一致性,并能捕捉到季节性变化,GLEAM与观测值吻合度较高并拥有适用性,MOD16在大部分站点性能较差；(2) 在空间上,GLEAM与EB-ET_V2和GLDAS存在更高的相关性(相关系数R>0.88)和一致性(一致性指数IOA>0.89),各产品季节时空分布有较大的差异,尤其是春季,相对其他产品,MOD16在大部分区域夏季低估且冬季高估。(3) 除MOD16外的各产品年平均ET大小相差较大,多年平均的高原ET大小排序为ERA5_Land(401.46mm/年)>PML(334.37mm/年)>GLEAM(298.46mm/年)>EB-ET_V2(271.39mm/年) >GLDAS(249.67mm/年), 六套产品估算的青藏高原的总体年蒸发量为330.59mm/年。青藏高原不同蒸发产品的比较有助于对高原蒸发的动态变化有更深入的了解, 可以为青藏高原水资源评估和区域水管理提供参考。
The uncertainties of evapotranspiration (ET) products developed based on satellite remote sensing and observations with different spatial and temporal resolutions still exist in the Tibetan Plateau (TP), limiting the application in hydrometeorological and climate assessment. Six ET (PML, EB-ET_V2, GLEAM, GLDAS, ERA5 and MOD16) products were evaluated based on eddy observations and the differences between the products were compared, and the uncertainty of ET products in the TP region was analyzed. The results show that: (1) There is a good correlation and consistency between the flux towers and the ET products of the corresponding pixel, and the seasonal changes can be captured. GLEAM has a high degree of agreement with the measurements and has applicability. MOD16 has poor performance at most sites. (2) Spatially, GLEAM has higher correlation (the correlation coefficient, R>0.88) and consistency (Index of agreement, IOA>0.89) with EB-ET_V2 and GLDAS. There are big differences in the temporal and spatial distribution of various products in the seasons, especially in spring. Compared with other products, MOD16 is underestimated in summer and overestimated in winter in most regions. (3) The annual average ET of each product except MOD16 is quite different. The ranking of the average ET for many years is ERA5 (401.46mm/year)>PML (334.37mm/year)>GLEAM (298.46mm/year)>EB-ET_V2 (271.39mm/year)>GLDAS (249.67mm/year). The total annual evaporation in the effective area is 330.59mm/year. The assessment results table helps to have a deeper understanding of the quality and dynamics of ET products on the TP, which can provide a reference for water resources assessment and regional water management on the TP.