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Description
This work introduces the Ground--Latent Interferometric Model (GLIM), a physics-based representation of the interferometric response to soil moisture variations building upon the formulation in [2]. GLIM represents the observed response as the superposition of two physically distinct scattering mechanisms: a temporally stable Ground contribution, providing a common interferometric phase reference, and a moisture-dependent Latent contribution associated with subsurface dielectric variations. Their separation is achieved through a Temporal Sum of Kronecker Products (T-SKP) decomposition, extending the SKP formulation [1] to the multi-temporal PolInSAR domain. The Ground contribution is used for phase calibration, while the isolated Latent response is inverted to retrieve Soil Moisture Anomalies (SMA) without requiring in-situ calibration or site-specific tuning.
GLIM and its inversion are experimentally assessed using the HydroSoil campaign [3], comprising more than 31,000 C-band acquisitions collected every 10 minutes over complete Barley and Corn phenological cycles. The inversion is assessed throughout the crop cycles, showing that retrieval performance is primarily controlled by the observability of the Latent contribution as vegetation develops. The evolution of the Latent-to-Ground Ratio (LGR) further provides a physical interpretation of the transition from soil- to vegetation-dominated scattering and of the recovery of soil observability during senescence.