TERENO Data Validation: Polarimetrically Derived vs. Ground Measured Soil Moisture

During the TERENO campaign in May/June 2011 fully polarimetric L-band airborne SAR data was acquired by DLR’s novel F-SAR sensor. The measurements were performed for the TERENO test sites “Ammer Catchment - Fendt” (part of the Bavarian Alps/pre-Alps observatory), “Bode Catchment - Schäfertal” (part of the Harz/Central Lowland Observatory) and the “Rur Catchment - Merzenhausen” (part of the Eifel/Lower Rhine Valley Observatory). Simultaneously in-situ soil moisture measurements were taken from mobile FDR probes. A newly developed hybrid decomposition and inversion approach for the detection of soil moisture under vegetation cover was applied to the fully polarimetric SAR data for validation with the in situ measurements. The validation for the three test sites shows an RMSE of 34 vol.% for Ammer Catchment - Fendt, 4 vol.% for Bode Catchment - Schäfertal and 9 vol.% for Rur Catchment - Merzenhausen. A good performance is obtained under dry (< 25 vol.%) hydrological conditions within the Bode and Rur catchments