基于理论参数空间的遥感蒸散模型构建及验证

遥感数据提供了估算区域蒸散的重要数据源,基于VFC/LST参数空间构建了改进的遥感蒸散模型(EML)。在EML中,每个像元构建其专属的理论参数空间,并基于水分亏缺指数(WDI)实现目标像元的蒸散估算。使用SMACEX实验观测数据对模型进行评估,区域尺度的模型评估使用来自于Landsat 7ETM+的遥感参数。评估结果表明EML可以实现可靠的区域通量估算。潜热通量估算的平均绝对误差(MAD)和均方根误差(RMSD)分别为62.20和74.17 W/m~2,感热通量估算的MAD和RMSD分别为43.37和49.02 W/m~2。使用传统的梯形参数空间模型(TIM)与EML进行对比,结果表明EML模型克服了TIM模型的主观性和不确定性。研究结果表明:EML模型能够实现可靠的蒸散估算,且优于传统的梯形参数空间模型TIM,并适用于非均匀下垫面的蒸散估算。

A Remote Sensing Evapotranspiration Model for Land based on the Theoretical Trapezoid Space

Satellite remote sensing provides a promising ways to estimate regional evapotranspiration (ET) in a spatially distributed manner.In this study,an improved Evapotranspiration Model for Land (EML) is proposed based on the trapezoid framework of VFC/LST space.In EML,a VFC/LST trapezoid space is theoretically defined for every pixel and then ET is estimated based on the Water Deficit Index (WDI).The proposed model was applied to the Soil Moisture\|Atmosphere Coupling Experiment (SMACEX) site.Regional scale evaluation with remotely sensed data set from Landsat 7 ETM+ was carried out to assess the performance of ETEML.The evaluation shows that EML is capable of estimating reliable surface heat fluxes.In this study,the Mean Absolute Difference (MAD) and root mean square deviation (RMSD) of Latent heat Flux (LE) estimates based on EML are 62.20 and 74.17 W/m²,respectively.The MAD and RMSD of sensible heat flux (H) estimates from ETEML are 43.37 W/m² and 49.02W/m²,respectively.A further inter\|comparison between the Trapezoid Interpolation Model (TIM) and EML is undertaken and the results indicate EML eliminated the subjectivity and uncertainties related with TIM.Overall,results suggest the EML is capable of estimating reliable surface heat fluxes and greatly promote the application of the trapezoid framework\|based ET modeling approaches to heterogeneous surfaces.