ALOS−PalSAR Pol−InSAR Data Analysis: First Results

This paper presents a first calibration and quality analysis of Pol−InSAR data acquired by the ALOS−PalSAR based on deterministic and extended scatterers. The calibration of Pol−InSAR data requires the estimation and compensation of polarimeteric and interferometric system and propagation (through the ionosphere and atmosphere) induced distortions. Constant phase errors/offsets appear in the polarimetric phase (i.e. phase difference between images acquired at different polarisations) as well as in the interferometric phase (i.e., phase difference between images acquired with a spatial and/or temporal baseline) as a constant offset that has to be compensated. Tougher to deal (and to calibrate) are time varying instrument and or propagation phase errors as they introduce a time varying phase imbalance in the polarimetric measurement and interfere with the topographic phase estimation of the interferometric measurement. The variation can be within a single scene and/or between the two interferometric image pairs. The effect of the individual system and propagation induced phase distortions is discussed and different calibration scenarios/strategies are addressed. A first ALOS/PalSAR Pol−InSAR data quality assessment − with respect to established and new Pol−InSAR applications − will be discussed and first results obtained from the analysis of Pol−InSAR data acquired during the CAL/VAL phase will be shown.