Universal Statistics for the Three Normalized Stokes Parameters for Multilook Data— Application to Signals Scattered by Layered Structures With Slightly Rough Interfaces

The polarization state of electromagnetic (EM) waves scattered from a random medium is given within the Poincaré space by the three normalized Stokes parameters. Polarimetric radar data are frequently multilook processed to reduce signal fluctuations by spatially averaging the scattered signals. In this article, a universal probability law is established, applicable to each of the three normalized Stokes parameters for multilook configurations and valid for a multivariate Gaussian model. As an application case, we consider the scattering of a polarized monochromatic plane wave from a stratified ground with an arbitrary number of slightly rough interfaces. Resulting expressions are studied for a snowy ground in L-band and are validated by comparison with Monte Carlo simulations.