Interferometric Coherence Characteristics with High Resolution Satellite Syntheric Aperture Radar

Recently high-resolution space-borne synthetic aperture radar (SAR) systems with various polarizations have been launched and operated successfully. Data acquired by these systems have shown good results for various geodetic interferometric SAR (InSAR) applications [1-5]. In this study we evaluate the coherences characteristics of high-resolution data acquired by TerraSAR-X (X-band), ALOS (L-band), Radarsat-2 (C-band) and low-resolution data acquired by Radarsat-1, ERS, Envisat (C-band), Jers-1 (L-band) over southern Florida, U.S.A. Our coherence analysis reveals that the high-resolution X-band (3.1 cm wavelength) TerraSAR-X (TSX) data has a high coherence level, similar to that of the L-band (24 cm) ALOS data, even in wetland areas (> 0.35). Furthermore, the TSX coherence values in both urban and wetland areas are significantly higher than that of the C-band (5.6 cm) Radarsat data. The high TSX coherence is a surprising result, because according to common vegetation scattering theories, the shorter wavelength radar pulse interacts mostly with upper sections of the vegetation and, hence, does not provide good stable scatterers over time. We suggest that the higher coherence values of the TSX data reflect the data's high-resolution, in which stable and coherent scatterers are better maintained. The contribution of pixel resolution to the coherence is also detected in Radarsat-1 data showing that fine-beam data (7 m pixel resolution) is significantly higher than that of the standard beam (20 m pixels) coherence. We will continue this preliminary study by conducting