【摘要】 主动微波遥感监测土壤水分具有全天时、全天候并对地物有一定的穿透能力等特点,突破了传统测量方法和光学遥感获取土壤水分的局限。文中在分析植被对微波信号影响的基础上,总结了当前国内外基于主动微波遥感监测植被覆盖地表土壤水分的原理和方法,指出利用"水-云模型"从总的极化雷达后向散射中去除植被影响后,能够改进后向散射系数和土壤含水量之间的关系。最后利用ENVISAT ASAR数据,结合实地采样获得的土壤含水量数据拟合两者之间的关系,结果表明农作物覆盖地表土壤水分变化的估算算法还需要进一步发展和改进以提高反演精度。更多还原

【Abstract】 As an important factor in the energy exchange processes between land and atmosphere,soil moisture has strong effect on the land surface evapotranspiration,runoff and C-circulation.Measurements of soil moisture in a large area have great application potential in the fields of hydrology,meteorology and agriculture.Compared with optical and thermal-infrared sensors,satellite system with sensors of active microwave remote sensing has more advantages to monitoring soil moisture because of its working all day and all weather and powerful penetration ability,namely,its signals is independent of cloud cover or illumination conditions,which is particularly the case with tropical areas where cloud and rain occur with high frequency in a year.By analyzing the vegetation impact on the signals of the microwave,the principle and methods of soil moisture monitoring based on active microwave remote sensing at home and abroad are reviewed.It is pointed out that the correlation between the backscattering coefficients and soil moisture can be improved after the vegetation effects on the estimation of soil moisture content are eliminated from the total polarization radar backscattering by using "water-cloud" model.The curve between the backscattering coefficient and ground measured soil moisture after eliminating vegetation effect is simulated by using the ENVISAT ASAR data.The results show that the estimation method of soil moisture content should be further improved in the areas covered by vegetation.更多还原