基于Landsat影像的ALEXI模型小流域验证

基于静止卫星数据开发的陆气相互作用模型(ALEXI模型)为地表能量平衡过程分析提供了大尺度空间拓展,为认识大尺度的陆气相互作用提供了新途径,已被应用于干旱监测、流域水文分析以及气候变化研究。使用高精度卫星分辨率获得的通量结果对ALEXI进行初步的验证与评估,选择下垫面类型复杂的小流域为研究区,以比较成熟的基于Landsat流域分析的SEBAL模型结果为验证源,对比分析同时期ALEXI模型的地表通量结果,研究发现ALEXI模型与SEBAL模型能够反映较一致的地表能量交换信息格局,统计分析能够得到较一致的结果。此外,由于模型自身的限制因素以及地表观测误差的影响,还需进一步开展定量对比验证方面的工作。

Evaluation of Atmosphere Land Exchange Inversion Model in Regional Scale based on Landsat Imagery

It is promising way to analyze large scale surface energy balance from two source model,which widely used to map local evapotranspiration pattern,detect regional drought and climate change study.Based on thermal infrared remote sensing image and field meteorological parameters,the Atmosphere-land Exchange Inversion Model (ALEXI) can examine land surface process in continental scale,further the hourly datasets from geostationary platform make possible integrate field measurements and model results.However,such great capacities of ALEXI model have weakness in its validation results that involved in the inappropriate spatial scale between satellite images and field measurements,even Large Aperture Scintillometer (LAS) measurements can’t meet the heterogeneous area comparison requirements in 6 km×6 km area.In this study,we assumed that the surface energy balance algorithm for land model (SEBAL) from high resolution image could catch more reasonable regional surface energy balance pattern,which was verified by many studies in local scale.The land surface balance results from SEBAL model based on Landsat images were considered as the data source for ALEXI model (MTSAT satellite platform) validation in the same period.The study showed that ALEXI model and SEBAL model can get a more consistent surface energy exchange patterns,and statistical analysis of the ALXEI model also provided well distribution among different land cover.Combined with geostationary satellite data,ALEXI model can be a promising method for monitoring land-atmospheric interaction.In addition,this study was executed in small watershed over northern China,and the quantitative validation of ALEXI model also need further work to improve the model accuracy in more heterogeneous study area.