Random Surface Scattering Models of RR Polarization for SoOp-R/GNSS-R Application

摘要: —LR polarization is commonly used for the
corresponding geophysical parameters retrieval in GNSS#2;
R(Global Navigation Satellite System-Reflectometry) or SoOP-R
(Signal of Opportunity-Reflectometry) . However, the other
polarization of the reflected signals has attracted more and more
attention with the development . The popular used equation for
RR polarization demonstrates that it decreases as the soil
moisture content increase and this is in contradiction with the
experiment data. Here, three new models have been developed:
Spec4PolR (Specular reflectivity model for polarization GNSS#2;
R), SPM4Pol (small perturbation model for polarization GNSS#2;
R), and Umich4Pol (Umich model for polarization GNSS-R).
The Mueller matrix of these three models has been presented
and the wave synthesis technique is employed to calculate the
reflectivity at RR polarization. Spec4polR employs only three
elements in the Mueller matrix for the final reflectivity, while
five elements for Umich4polR participate in the calculation and
although all the elements of the SPM4Pol have constructed the
Mueller matrix and only nine elements have been employed for
calculation. Each elements' effects on the soil moisture content
are presented and the final reflectivity at RR polarization has
been illustrated. However, due to the simple formulations of
Spec4Pol, its reflectivity at RR polarization still decreases as the
soil moisture content increase. while the results of SPM4Pol and
Umich4Pol are consistent with the measured data and the
reflectivity at RR polarization increase as the soil moisture
content increase. The accurate forward calculation of RR
polarization is crucial for the subsequent retrieval algorithm of
polarization GNSS-R/SoOP-R.