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1. chinaXiv:201904.00084 [pdf]

A simulation study of GNSS-R polarimetric scattering from the bare soil surface based on the AIEM model

吴学睿
Subjects: Geosciences >> Geochemistry

In the past two decades, Global Navigation Satellite System-Reflectometry (GNSS-R) has emerged as a new remote sensing technique for soil moisture monitoring. Some experiments showed that the antenna of V polarization is more favorable to receive the reflected signals, and the interference pattern technique (IPT) was used for soil moisture and other geophysical parameters retrieval. Meanwhile, the lower satellite elevation angles are most impacted by the multipath. However, electromagnetic theoretical properties are not clear for GNSS-R soil moisture retrieval. In this paper, the Advanced Integral Equation Model (AIEM) is employed using the wave synthesis technique to simulate different polarimetric scattering at the specular directions. Results show when the incidence angles are larger than 70º, scattering at RR polarization (The transmitted signal is Right Hand Circular Polarization (RHCP), while the received one is also RHCP) is larger than that one at LR polarization (The transmitted signal is RHCP, while the received one is Left Hand Circular Polarization (LHCP)), while scattering at LR polarization is larger than that at RR polarization for the other incident angles(1º~70º). There is an apparent dip for VV and VR scattering due to the Brewster angle, which will result in the notch in the final receiving power and this phenomenon can be used for soil moisture retrieval or vegetation corrections. The volumetric soil moisture (vms) effects on their scattering are also presented. The larger soil moisture will result in lower scattering at RR polarization, and this is very different from the scattering of the other polarizations. It is interesting to note that the surface correlation function only affects the amplitudes of the scattering coefficients at much less level, but it has no effects on the angular trends of RR and LR polarizations.

submitted time 2019-04-10 Hits6053Downloads325 Comment 0

2. chinaXiv:201904.00085 [pdf]

全极化GNSS-R陆面参数延迟多普勒图模型

吴学睿; 金双根
Subjects: Geosciences >> Geodestics

目前,针对GNSS-R的研究多从观测角度出发,对其散射机理研究相对较少。本文针对GNSS-R(GNSS-Reflectometry)反射信号陆面参数的延迟多普勒图理论模型展开研究,对于陆面参数(裸土、植被)的双站散射特性的计算采用修改后的随机粗糙面散射模型和零阶/一阶辐射传输方程模型。通过该模型模拟分析了裸土、植被参数变化时,相应的延迟多普勒图的变化。同时为利用极化信息进行相应地物参数的后向反演,模型中增加全极化计算功能。全极化GNSS+R陆面参数延迟多普勒图理论模型的研究有助于星载数据的解释、地表实验设计、数据仿真和后向反演算法的开发。

submitted time 2019-04-10 Hits5767Downloads865 Comment 0

3. chinaXiv:201904.00086 [pdf]

GNSS-R/IR 土壤水分遥感研究现状

吴学睿; 金双根; 王峰
Subjects: Geosciences >> Geodestics

GNSS-R/IR是利用导航卫星反射信号对地观测的新方式,是国内外研究的热点技术。由于GNSS卫星群主要工作在穿透性比较强的L波段,因此适宜进行地表土壤水分监测。本文根据不同的遥感平台,详细叙述了地基、塔基、机载和星载GNSS-R技术土壤水分监测的发展现状,同时综述了辐射计联合GNSS-R技术进行土壤水分监测的发展状态以及GNSS-R地基和星载接收机的发展现状并探讨了GNSS-R/IR进行土壤水分反演的中的重点和难点内容。

submitted time 2019-04-10 Hits2973Downloads270 Comment 0

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