Subjects: Astronomy >> Astrophysical processes Subjects: Geosciences >> Geodestics submitted time 2024-02-05
Abstract： —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.
Subjects: Geosciences >> Geodestics submitted time 2019-04-10
Abstract： " GNSS-R is a new promising remote sensing technique, which utilizes the reflected signals of GNSS constellation to remotely sense the ocean or land surface. At present, most of the existing research are based on the experimental observations, few theoretical studies have been carried out. This paper has developed a fully polarization GNSS-R delay Doppler map for land geophysical parameters study. This theoretical model was based on the ocean surface GPS scattering model, after the modifications, it has been used for the land surface. As for the calculations of land geophysical parameters (bare soil and vegetation), random surface scattering model and the first order radiation transfer equation model were used. Effects of bare soil and vegetation parameters on the delay Doppler maps were simulated. In order to use the polarization information for backward inversion, our developed theoretical model has the ability of fully polarizations calculations, i.e. RR, LR, HR and VR pol. This theoretical model is a mechanism tool for the data explanation of space borne mission, experimental campaign design, data simulations and the backward inversion algorithm development. "
Peer Review Status:
Awaiting Review
Subjects: Geosciences >> Geodestics submitted time 2019-04-10
Abstract： " GNSS-R has been emerged as a new and promising remote sensing technique in recent years. Due the strong penitration properties of L band microwave length, it is suitable to monitor soil moisture using this technique. According to different remote sening platforms, progresses of soil moisture monitoring using GNSS-R technique with ground-based, tower-based, airborne and space borne platforms are presented in this paper, while a detail review of GNSS-R joint with microwave radiometer is also given in this paper. "
Peer Review Status:Awaiting Review
Subjects: Geosciences >> Geodestics submitted time 2019-04-04
Abstract： " In order to extend the applications GNSS-R/IR（GNSS-Reflectometry /Interferometric Reflectometry ) remote sensing technique to soil freeze/thaw process detection, soil(frozen/thawn) mixing permittivity models are employed to calculate the soil permittivity. Bistatic full-polarizationcoherentscattering model and random roughness surface scattering model are used to calculate the coherent and non-coherent scattering, which result in the variations of GPS multipath observables and DDM（Delay Doppler Map） waveforms, respectively. When the soil freeze/thaw process occurs, theoretical simulations indicate that soil freeze/thaw process induce the abrupt permittivity changes and affect the obvious variations of GNSS-R/IR signals.In this way, theoreticalfundamentals for soil freeze/thaw process detections are presented.
Peer Review Status:Awaiting Review
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