中文摘要：

土壤水分是农业干旱监测最重要的指标之一。文章全面回顾了光学遥感和微波遥感土壤水分遥感反演进展，重点讨论了符种反演方法的优点和不足。光学遥感中，热惯量法和作物缺水指数法可分别较好地应用于裸露地和作物覆盖地的土壤水分监测；距平植被指数、植被条件指数采用了植被指数因子实现农业旱情监测，温度植被指数、植被供水指数和条件植被温度指数同时考虑了作物植被指数和地表温度。微波遥感被认为是当前土壤水分监测中最有效的方法。主动微波遥感空间分辨率较高，但对土壤粗糙度和植被敏感；被动微波遥感空间分辨率低，重访周期短，对大尺度农业旱灾监测具有较大潜力。为提高农业旱灾监测巾土壤水分遥感反演的精度和效率，采用光学遥感和微波遥感的结合可能是较为实际的方法。

英文摘要：

Soil moisture is one of the most important indices for agricultural drought monitoring. In this paper we present a comprehensive review for the progress in remote sensing of soil moisture, with focus on discussion of the method details and problems existing in soil moisture estimation from remote sensing data. Thermal inertia and crop water stress index （CWSI） can be used to soil moisture estimation of bare soil and vegetation environments respectively. Anomaly vegetation index （AVI） and vegetation condition index （VCI） are another alternative methods for soil moisture estimation with normalized difference vegetation index （NDVI）. Both NDVI and land surface temperature （LST） are considered in temperature vegetation index （TVI）, vegetation supply water index （VSWI） and vegetation temperature condition index （VTCI）. Microwave remote sensing is the most effective technique for soil moisture estimation. Active microwave can provide high spatial resolution but is sensitive to soil rough and vegetation. Passive microwave has a low resolution and revisit period but it has more potential for large scale agricultural drought monitoring. Integration of optical and microwave remote sensings may be the practical method of drought monitoring in both accuracy and efficiency.