Quantification and compensation of temporal decorrelation effects in polarimetric SAR interferometry

Abstract

Several studies showed that Pol-InSAR data especially at lower frequencies such as L- and P-band, are sensitive to the vertical distribution of scatterer along forest height. A model-based inversion of forest height and structural parameters was introduced and demonstrated. However, in repeat-pass airborne/spaceborne SAR system, temporal decorrelation is one of the most critical parameter for a successful Pol-InSAR forest parameter inversion. Temporal decorrelation is caused by the dynamic changes of the scatterers and/or the variation of the dielectric properties of the scatterers within the scene occurring in the time between the two SAR acquisitions. Due to its random character it is difficult to estimate and compensate temporal decorrelation contributions from the complex interferometric coherence. Temporal decorrelation lowers the estimated coherence and therefore also the estimated volume decorrelation which is directly related to the vertical distribution of scatterers. A biased (lowered) volume coherence leads to a biased forest parameter estimation in Pol-InSAR inversion. In this study, we assess the quantitative analysis of temporal decorrelation as a function of time using experimental data acquired by DLR’s E-SAR system. Then we evaluate the implementation of multi-baseline inversion technique for compensating temporal decorrelation. The behavior and compensation of temporal decorrelation will be demonstrated by means of three campaign data sets: BioSAR 2007 and TempoSAR 2008/2009.