Vegetation effects on L-band soil moisture retrieval - Lessons learned from 5 years of ALOS PALSAR observations

Apart from surface roughness effects the major impediment to accurate quantitative estimations of surface soil moisture content from SAR data is probably the presence of a vegetation cover attenuating the radar backscatter. In this paper, we report observations of vegetation effects on ALOS soil moisture products. A multi-temporal set of (quad/dual) polarimetric PALSAR images is used to investigate the effects of different agricultural crops on the L-band soil moisture retrieval. The vegetation effects on co-(HH) and cross-polarized (HV) backscattering coefficients, total power, as well as on the scattering entropy and alpha angle were analyzed based on correlation analysis between PALSAR observables and geophysical parameters. The impact on the soil moisture retrieval is investigated using the IEM and an empirical approach.