Use of TerraSAR-X data to retrieve soil moisture over bare soils agricultural fields

The retrieval of the bare soil moisture content from TerraSAR-X data is discussed using empirical approaches. Two cases were evaluated: (1) one image at low or high incidence angle, (2) two images, one at low incidence and one at high incidence. This study shows in using three databases collected between 2008 and 2010 over two study sites in France (Orgeval and Villamblain) that TerraSAR-X is a good remote sensing tool for the retrieving of surface soil moisture with accuracy about 3% (RMSE). Moreover, the accuracy of the soil moisture estimate does not improve when two incidence angles (26°-28° or 50°-52°) are used instead of an only one. When compared with the result obtained with a high incidence angle (50°-52°), the use of low incidence angle (26°-28°) does not enable a significant improvement in estimating soil moisture (about 1%).