Analysis of the Reconstruction Accuracy of Compact Polarized SAR Pseudo Quad-Pol Data for Use in Ocean Surface Observations

This paper assesses the capability of Compact Polarized (CP) Synthetic Aperture Radar (SAR) to explore ocean surface backscattering by reconstructing the pseudo quad-pol data. Besides using Souyris or Nord algorithms, 8 scenes of Radarsat-2 quad-polarized images are used to develop an empirical model for estimating the initial value of N in Collins's algorithm. The robustness the three published algorithms are discussed together with the reconstruction error of polarization scattering matrix [S]. The comparisons show that Collins's algorithm is superior to the other two algorithms in terms of reconstruction errors for the HH, VV, especially, the HV channels. In addition, the influence of each algorithm on polarimetric parameters is investigated. Based on the retrieval of the polarimetric parameters, it is concluded that Souyris, Nord and Collins algorithms all have similar (high) accuracies for copolarization backscattering coefficient σ
⁰
HH
, σ
⁰
vv
, co-polarization correlation coefficient
$p$
and first eigenvalue l
1
, while for cross-polarization backscattering coefficient σ
⁰
vv
and scattering angle α, the accuracy of Collins's algorithm performs better than that of Souyris or Nord. Although all three algorithms produced low accuracies for second eigenvalue
$l$
2
, third eigenvalue l
3
, scattering entropy
$H$
and scattering anisotropy A, the results obtained using Collins algorithm were better than those produced by the other two algorithms.