柴达木盆地土壤湿度的遥感反演及对蒸散发的影响
Soil Moisture Retrieval from Remote Sensing and Its Impact on Evapotranspiration in Qaidam Basin

摘要： 土壤水分是地下水-土壤水-大气水循环系统的核心与纽带，蒸散是该系统的重要驱动力。从区域尺度上研究土壤含水量的分布特征及土壤含水量对蒸散的影响对干旱区的生态环境保护具有重要意义。基于MODIS数据和GLDAS数据，应用表观热惯量法对GLDAS地表0~10 cm土壤湿度数据降尺度处理，估算柴达木盆地平原区2014年间6—9月的月均土壤湿度，并结合归一化植被指数(NDVI)和实测土壤湿度数据对反演结果进行验证；利用地表能量平衡系统(SEBS)模型对平原区9个子流域的日均蒸散量进行计算，分析了土壤湿度与日均蒸散量之间的关系。结果表明：反演得到的表观热惯量(ATI)与GLDAS地表0~10 cm土壤含水量数据相关性较好，决定系数R2整体在07以上；利用ATI对GLDAS数据降尺度处理，得到的土壤含水量与NDVI和实测土壤湿度的决定系数R2分别为0954和0791，因此使用ATI法对GLDAS土壤含水量数据降尺度反演柴达木盆地平原区土壤湿度是可靠的。平原区日蒸散量与土壤湿度呈明显的正相关关系，决定系数R2整体在096以上，在影响蒸散的各考虑因素中，土壤湿度对蒸散的影响远大于其他因素。
Abstract: Soil moisture is the core content and link of the groundwatersoil wateratmospheric water circulation system. Evapotranspiration(ET) is the important driving force of this system. The study of distribution of soil moisture and its effect on ET from regional scale has great significance on ecoenvironmental protection in arid areas. Based on MODIS and GLDAS data, the monthly soil moisture from June to September in 2014 was estimated in plain area in Qaidam Basin after downscale treatment of 0-10 cm GLDAS surface soil moisture data using Apparent Thermal Inertia(ATI) method. The retrieval results were validated by combination of field measurement and NDVI. Furthermore, the mean daily ET was estimated in 9 drainage basins of plain using the Surface Energy Balance System(SEBS), and the relationship between soil moisture and ET was also analyzed in this study. The result indicated that the correlation between ATI soil moisture and 0-10 cm downscaling GLDAS data was good and the determination coefficient R2 is more than 07. The determination coefficient R2 between retrieval result of soil water content and field measurement is 0791, and the R2 between soil water content and NDVI is 0954. Therefore, it is reliable to retrieve soil moisture in Qaidam Basin based on downscale treatment of GLDAS data using ATI method. The daily ET is positively correlated with soil moisture and the determination coefficient R2 is more than 096. The impact of soil moisture on ET is much more than other impact factors