Numerical Modeling of Subsurface Layer Resonance-Based Interferometric SAR (InSAR) Correlation Fluctuations

We numerically explore the magnitude of the interferometric coherence (correlation) between two co-polarized SAR observations of natural scenes, examining specifically the "volumetric" correlation associated with electromagnetic ground penetration. Our scattering model quantifies the effects, on InSAR coherence, of subsurface layers guiding the incident wave via a succession of internal, specular reflections ("multi-bounce"). As the paper's first contribution, we reveal that multi-bounce engenders "interferometric" resonances that induce deep, periodic degradation (versus InSAR baseline length) of correlation. Second, the correlation's periodic variation versus InSAR spatial baseline, with period length invariant to variations in subsurface properties, allows robust multi-baseline extraction of subsurface topography.