卫星微波遥感结合可见光遥感估算黄河源区土壤湿度研究

利用欧洲环境卫星(ENVISAT)搭载的高级合成孔径雷达ASAR(Advanced Synthesis Aperture Radar)交叉极化模式(APP)2009年8月9日和10月6日的数据对青藏高原东北部玛曲地区土壤湿度进行了估算。对于裸土区域采用表层微波后向散射几何光学模型GOM(Geometry Optics Model),对于植被覆盖度大的区域利用“水—云”模型处理植被层对后向散射系数的影响,取得了较好的结果:遥感估算的土壤湿度值和地面实测值之间的均方根误差RMSE<0.05,决定系数R²>0.82,表明该方法适合反演玛曲地区的土壤水分。从遥感估算的总体结果可以看出:山谷和陡峭山坡的反演结果相对较差,而在相对平坦的地区反演结果较好,估算的土壤湿度值在0.20~0.50 m³/m³之间。

A Study on Estimating Soil Moisture Using Microwave Remote Sensing Combined with Optical over the Source Region of the Yellow River

The estimation of soil moisture in Maqu in northeast Tibet Plateau on August 9 and October 6 2009 is carried out using the European environment satellite (ENVISAT) Advanced Synthesis Aperture Radar(ASAR) APP mode of HH and VV polarization active microwave data.Surface microwave backscatter geometrical optics model (GOM) is used in the bare soil,the effect of the vegetation layer can be eliminated from the backscatter coefficients by a semi-empirical “water-cloud” model,which have achieved good results.The RMS error R between estimated soil moisture using remote sensing and ground measurements is less than 0.05,while the coefficient of determination R² is greater than 0.82,which indicates that this method is suitable for the inversion of the soil moisture in Maqu area.The inversion results of remote sensing show that shadow valley and the steep sides of mountains are relatively poor,and the inversion results in relatively flat area are good,and the value of the estimated soil moisture are mostly between 0.20 and 0.50 m³/m³.