以高级合成孔径雷达（ASAR）影像数据和地面实测数据为基础，分析了裸土、低覆盖（覆盖度为0．2左右）冬小麦麦地的后向散射与土壤含水量、地表粗糙度及小麦覆盖度之间的关系，探讨了裸土和冬小麦麦地土壤含水量及小麦覆盖度的反演方法。分析结果表明：①裸土后向散射系数受地表粗糙度和土壤质地的综合影响较大，裸土的后向散射和土壤含水量正相关关系未达显著，反演裸土土壤含水量必须考虑这两个因素的影响。②冬小麦麦地两种极化后向散射对土壤含水量和小麦覆盖度的敏感性差异明显。由于小麦植株与土壤的水平同极化后向散射差异较大，水平极化后向散射系数和小麦覆盖度及土壤含水量相关性达到显著；冬小麦麦地的垂直同极化后向散射对土壤含水量较敏感，垂直极化后向散射系数和土壤含水量的相关性达到显著，但与小麦覆盖度的相关性相对较低。据此，利用冬小麦麦地的两个同极化后向散射系数，建立了后向散射系数与土壤含水量和小麦覆盖度之间的关系模型，实现了小麦覆盖度和冬小麦覆盖下的土壤含水量反演。验证结果表明：土壤含水量和小麦覆盖度反演结果与地面调查和测量结果一致。

This paper focused on retrieving soil water content of bare and winter wheat planted field from ENVISAT ASAR image.The relationship between bare soil's back scattering coefficient and soil water content or land surface roughness was analyzed,and the relationship between winter wheat field's backscattering coefficient and soil water content or wheat coverage was also analyzed.The result have shown:(1) because bare soil's backscattering was greatly affected by land surface roughness and soil texture,the positive correlation existed between bare soil's backscattering and soil water content was not significant,therefore their effects must be considered in the retrieval of soil water content.(2) The difference of sensitivity of two(polarization's) backscattering to soil water content and wheat coverage was obvious.The difference of the horizontal polarization backscattering coefficients of winter wheat and bare soil was great.Therefore,the horizontal polarization backscattering coefficient was significantly correlated to wheat coverage and soil water content.The vertical polarization backscattering coefficient of winter wheat planted field was sensitive to soil water content.Therefore,the vertical polarization backscattering coefficients was significantly correlated to soil water content,but not significantly to wheat coverage.Combining two polarization backscattering coefficients of winter wheat field,the models between backscattering coefficients and soil water content or wheat coverage were built,and winter wheat coverage and soil water content under wheat canopy were obtained from ASAR image.As expected,the retrieved soil water content and wheat coverage are consistent with those of field measurements.