PolSAR Target Decomposition Technique to Estimate Ocean Surface Temperature and Salinity

Abstract

A novel method is proposed to estimate the seawater surface salinity and temperature from the data collected by synthetic aperture radar (SAR) systems of quad-polarimetry (quad-PolSAR). The proposed method requires the knowledge of the curves that characterize the dependence of the complex dielectric constant of the seawater surface on the salinity and temperature at the operating frequency of the PolSAR system. Simulated quad-PolSAR datasets are used to test the proposed method at 1.27 GHz, where the simulation process is described in the paper. The proposed method depends on the theory of SAR target decomposition (TD) with multiple component scattering model (MCSM), where the single-bounce covariance matrix is deduced from the covariance matrix of the quad-PolSAR data representing the backscattering from the seawater surface. The proposed method is applied to the simulated datasets resulting in good accuracy of the estimated values of the seawater permittivity and the corresponding salinity and temperature when compared with the ground-truth values. The effects of the environmental and operational conditions of the PolSAR system on the collected backscattering data are modeled as additive white Gaussian noise (AWGN). The dependence of the accuracy of the estimated seawater parameters on the signal-to-noise ratio (SNR) is investigated and quantitatively assessed.