Agricultural Vegetation Parameter Estimation using Pol-SAR: Retrieval of Soil Moisture

In this paper the focus is given to the soil moisture retrieval under a vegetation cover, exemplarily for two crop types winter wheat and rape. For this Pol-SAR data over a whole vegetation period were used acquired in the frame of the AGRISAR campaign in 2006 at L-band. The potentials and limitations over time are investigated by modifications of the model based Freeman decomposition in order to decompose the scattering contributions and to invert the surface and dihedral scattering component for soil moisture estimation. The applied decomposition approaches for agricultural land surfaces are suitable, but exhibit deficiencies in modeling the volume component, even though some improvements due to the modifications could be presented. In the end the soil moisture estimation does not perform constantly well over the whole acquisition period due to the complexity of the crop vegetation.