PROJECT TITLE :

Exploiting Polarimetric TerraSAR-X Data for Sea Clutter Characterization

ABSTRACT:

This paper presents a detailed characterization of sea/ocean muddle returns at X-band, imaged by TerraSAR-X (TSX) mission from the radiometric, statistical, and polarimetric standpoints. Totally different TSX data takes, covering the everyday spaceborne incidence angle region (twenty°–45°), are analyzed: twin-polarized (twin-pol) and experimental quad-polarized (quad-pol) knowledge have been used. The thermal noise of the receiver for quad-pol knowledge seems to be an vital limitation in the sea characterization from TSX, particularly at high incidence angles (higher than 36°), where low signal-to-noise ratios (SNRs) will impair the right data distribution fitting and the polarimetric backscattering description. Statistical analysis shows large deviation from Gaussianity, indicating presence of texture, mainly in the tiny incidence region (twenty°–36°), with favorable SNR conditions. The totally different polarimetric features revealed contribution of nonpolarized scattering, related to the presence of breaking waves. This paper conjointly proposes and evaluates an extension of the well-known X-Bragg model, named X2-Bragg (extended-extended Bragg), that properly accounts for the impact of thermal noise and ocean clutter temporal decorrelation, thanks to the dual receive antenna (DRA) acquisition mode. Such further decorrelation sources, if not properly analyzed and accounted for in the physical-based mostly model description, could lead to an incorrect interpretation of the polarimetric properties and therefore the related erroneous geophysical parametric inversion from the real information. In this sense, the X2-Bragg proves its fitting to the experimental data, quantifying accordingly the presence of nonpolarized scattering in terms of the roughness parameter .