地表温度-植被覆盖度特征空间蒸散发遥感反演的空间尺度效应及干湿边确定方法研究

Evapotranspiration (ET) is one of the key components in the surface water and heat budget, and influences directly the transfer of water and heat in the soil-vegetation-atmosphere system. In light of the limitations in the estimation of regional evapotranspiration from the existing surface temperature-fractional vegetation cover characteristic space model, the spatial-scale effect of the sizes of both the area of interest and satellite pixel on the characteristic space will be firstly investigated through theoretical analysis, mathematical deduction, and by model application to satellite data (MODIS/TERRA and ASTER/TERRA) at different spatial resolutions. A soil-vegetation-atmosphere transfer (SVAT) model will be used to explore the physics of the ET estimation, especially the physics of the variation of the dry and wet edges in the characteristic space. A physical method of the determination of the dry and wet edges, together with a new surface temperature variation-fractional vegetation cover characteristic space, will be developed by applying the explored physics of the temporal variation of the dry and wet edges with satellite-retrieved surface net radiation, surface temperature, fractional vegetation cover/surface albedo. Ground-based LAS measurements will be used to validate the ET estimated by the newly developed characteristic space. The implementation of this project will improve the determination of the dry and wet edges, making it unaffected by the sizes of the area of interest and satellite pixel, and improve the accuracy in the estimation of regional ET from the commonly used contextual information-based ET method.

陆面蒸散发（ET）是地表水量平衡和能量平衡的重要组成部分，直接影响土壤-植被-大气系统中的水、热传输。本项目针对地表温度-植被覆盖度特征空间ET估算方法存在的不足，根据理论分析、数学推导和不同空间尺度遥感（MODIS/TERRA和ASTER/TERRA）数据的应用，首先研究特征空间法估算ET受研究区大小和像元分辨率影响的空间尺度效应，然后基于土壤-植被-大气水热传输模型探索特征空间ET估算方法中干湿边随地表特征参数时间变化的物理机理，通过卫星遥感（FY-2C）反演的净辐射、地表温度、植被覆盖度或地表反照率的应用和地面大孔径闪烁仪（LAS）观测数据的验证，发展出具有物理机理的特征空间干湿边确定方法，建立新的地表温度变化速率（或温差等）-植被覆盖度特征空间模型，改进目前利用遥感数据二维空间背景信息进行ET估算时干湿边确定随研究区大小及像元分辨率不同而变化的不足，提高特征空间估算陆面ET的精度。

陆面蒸散发（ET）是地表水量平衡和能量平衡的重要组成部分，直接影响土壤-植被-大气系统中的水、热传输。本项目针对地表温度-植被覆盖度特征空间ET估算方法存在的不足，基于理论推导及模型在卫星像元尺度的应用，分析了代表性空间变化信息模型(SEBAL与Ts-VI特征空间)在蒸散发估算方面的本质联系与异同点及模型估算ET差异的主要控制因子；根据理论分析、数学推导和不同空间尺度遥感（MODIS/TERRA和ASTER/TERRA）数据的应用，研究了空间变化信息模型SEBAL估算ET受研究区大小和像元分辨率影响的空间尺度效应；根据地表能量平衡原理，提出了特征空间理论干湿边的确定方法，发展了优于其他干旱指数的TRRVDI土壤水分干旱指数；提出了基于归一化Ts-VI特征空间的土壤水分遥感反演方法，解决了前人研究中土壤水分反演在不同大气强迫条件下不可比的问题。本项目的研究成果改进了目前利用遥感数据二维空间信息进行ET估算时干湿边确定随研究区大小及像元分辨率不同而变化的不足，提高了特征空间估算陆面ET的精度。共发表科技论文17篇，其中SCI论文13篇，EI 论文4篇。