The Impact of Temporal Decorrelation over Forest Terrain in Polarimetric SAR Interferometry

While polarimetric SAR interferometry (Pol-InSAR) techniques are today well established, a critical issue in the case of repeat-pass spaceborne measurements is temporal decorrelation, caused by changes within the scene occurring in the time between the acquisitions. Indeed, temporal decorrelation has been identified as the most critical factor for a successful implementation of Pol-InSAR parameter inversion techniques in terms of conventional space-borne repeat-pass InSAR scenarios. Similar to any other system induced decorrelation contribution, temporal decorrelation reduces the performance of Pol-InSAR techniques by biasing the volume decorrelation contribution used for parameter inversion. This leads to an increased standard deviation of the InSAR phase for the same number of looks and introduces a bias in the parameter estimates. In this paper first we analyze repeat-pass Pol-InSAR data acquired in the frame of dedicated experiments in order to quantify temporal decorrelation for temporal baselines in the order of days up to 4 and 8 weeks at Lband for two different forest types: temperate and boreal forests.