Study on Absolute Calibration Coefficient Improvement for ALOS PALSAR Data after Initial Calibration Check

The Advanced Land Observing Satellite (ALOS) was launched in 2006, carrying the Phased Array type L-band Synthetic Aperture Radar (PALSAR). Although three years have passed from the start of ALOS PALSAR observation, we know the PALSAR is in operation with greatly stability operation. However, we need to monitor its performance for the future sustainable operation in order to evaluate the temporal sensitivity variations of the PALSAR sensor and keep the calibration coefficient quality and its improvement. To achieve this goal, AIST (National Institute of Advanced Industrial Science and Technology) kicked off the PALSAR calibration and validation campaign in 2007. We especially focus on cross-polarization calibration and aim to propose an improved backscattering coefficient by evaluating the absolute calibration coefficient accuracy is evaluated, which is calculated for each polarization based on the groundtruth. In the calibration observations, we used two triangular trihedral corner reflectors (CRs) of size 2 m and 3 m for the like-polarization and our inbuilt prototype rotatable rectangular dihedral CR was used for the cross-polarization.