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利用Terra与Aqua两颗卫星的MODIS地表温度和植被指数数据,分别构建LST-NDVI与LST-EVI共四种不同组合的Ts-VI特征空间,并依据该特征空间提取温度植被干旱指数(TVDI)作为反映土壤干湿状况的指标,探讨一种合适的遥感监测藏北高原土壤湿度的方案,并基于同步的实地土壤表层含水量采样数据进行验证评价。研究表明,四种数据组合方案提取的TVDI分布图均能较好反映藏北土壤湿度,且Terra MODIS LST-EVI构建的特征空间提取TVDI指标效果最佳。在此基础上获得的藏北高原土壤湿度分级图表明,从东南到西北土壤湿度逐渐降低,并呈现明显的空间分异规律。
Based on the MODIS surface temperature and vegetation index data of Terra and Aqua, four Ts-VI feature spaces with different combinations of LST-NDVI and LST-EVI were constructed, and the TVDI was extracted based on the feature space. As an indicator to reflect the status of soil wet and dry conditions, a suitable remote sensing monitoring program of soil moisture in the northern Tibetan Plateau was discussed. The validation and evaluation were based on the simultaneous sampling data of surface soil moisture. The results show that all the TVDI maps extracted from the four data combination schemes can reflect the soil moisture in northern Tibet better and the TVDI index extracted by the feature space constructed by Terra MODIS LST-EVI is the best. On the basis of this, the graded maps of soil moisture in the northern Tibet Plateau show that the soil moisture from the southeast to the northwest gradually decreases, and the spatial variation pattern is obvious.