Evaluation of the predicted error of the soil moisture retrieval from C-band SAR by comparison against modelled soil moisture estimates over Australia

► The error of the existing ENVISAT ASAR GM soil moisture product was assessed. ► Independent top soil moisture estimates produced by the AWRA model were used. ► A high quality of the ASAR GM error estimate was demonstrated. ► The identical error model was proposed for the potential Sentinel-1 product.