耦合土壤水分的土壤蒸发和植被蒸腾遥感估算与验证研究

土壤水分关联着地表植被蒸腾和土壤蒸发，但利用经验和半经验的参数化方法难以准确模拟土壤水分亏缺下生态系统中土壤和植被水分耗散过程。本研究以土壤水分与双层能量平衡方程耦合为核心，利用涡动相关仪、自动气象站等地面观测数据以及遥感数据，通过考虑田间持水量和最大土壤含水量以及植被冠层导度模型，实现土壤水分亏缺条件下土壤蒸发和植被蒸腾过程精准模拟；准确地从地表温度中分解出土壤和植被组分温度，构建耦合土壤水分的地表蒸散发双层遥感模型。最后利用涡动相关通量观测数据，空间尺度扩展后的树干液流计和小型蒸渗仪观测数据，对模型估算结果进行真实性检验，探究土壤水分在基于能量平衡的地表蒸散发遥感估算模型中的应用前景、优势与不足。

Soil moisture is a critical nexus of the soil evaporation and plant transpiration over land surface. However, the processes of the water loss from soil and canopy in the ecosystem have not been adequately simulated due to a dearth of reliable models when the land surface is under soil moisture deficit. This program aims to couple soil moisture data to the two source energy balance model (TSEB-SM) by integrating multi-source data from the ground observations of eddy covariance systems, automatic weather stations, sap flows, microlysimeters and satellites. The evaporation efficiency can be estimated incombination with the field capacity and maximum water content, while the transpiration efficiency is constrained by a stomatal conductance model at canopy scale for soil water stressed ecosystem. The soil and canopy component temperature can be derived from the land surface temperature using a modified Priestly-Taylor equation where the soil limited evaporation and transpiration can be adjusted by a factor related to soil wetness. The TSEB-SM model will be adequately evaluated under a wide range of soil moisture content and environment conditions using ground measurements from flux towers, sap flow and microlysimeters. The project will significantly contribute to refinements in the TSEB model algorithms for estimating land surface evaporation and transpiration under unsaturated conditions. It is also expected to provide improved methods for assessing modeled transpirations at flux tower footprint scale.