ERS-ENVISAT Coherence Properties of Land Cover

ERS-ENVISAT coherence is a new SAR interferometric product with interesting properties due to the very short repeat-pass interval between acquisitions. When the requirements set by ERS-ENVISAT interferometry on baseline length and Doppler centroids are fulfilled, the ERS-ENVISAT coherence can present a large span of values. For an ERS- 2/ENVISAT image pair acquired over the region surrounding the city of Paris, bare soils have much higher coherence compared to forests and urban areas. As a consequence the use of the ERS- ENVISAT coherence for detecting forest cover changes and estimation of biophysical properties of regrowing forest / crops seems feasible. An analysis of the decorrelation phenomena for the ERS-ENVISAT coherence shows that (i) decorrelation can increase from near to far range if the common band filtering is not perfect, (ii) volume decorrelation is relevant because of the long baseline, and (iii) temporal decorrelation seems to be relevant for vegetation even at the 30 minutes interval time scale.

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