GNSS-R陆面遥感中反射信号的极化特性研究  

GNSS-R Land Remote Sensing about Reflected Signal's Polarization Characteristics

作　　者：吴学睿[1,2,3] 李颖[1] 

机构地区：[1]大连海事大学环境科学与工程学院,辽宁大连116026 [2]内蒙古赤峰学院资源与环境科学学院,内蒙古赤峰024400 [3]遥感科学国家重点实验室,中国科学院遥感应用研究所,北京100875

出　　处：《地球科学进展》2012年第8期895-900,共6页Advances in Earth Science

基　　金：遥感科学国家重点实验室开放基金项目“基于物理模型的GNSS-R土壤水分反演算法研究”(编号:OFSLRSS201010);辽宁省自然科学基金项目“GNSS-R微波遥感海冰监测”(编号:2010010111-401);国家自然科学基金青年科学基金项目“联合车载微波辐射计测量数据和理论模型的农田辐射特征研究”(编号:41101333)资助

摘　　要：GNSS-R是利用导航卫星的反射信号对海面或者陆面进行遥感的一种成本低、功耗小、时空分辨率相对较高的新型遥感手段。从机理上讲GNSS-R为双站雷达,以微波电磁散射模型为研究基础,对于右旋圆极化发射,右旋圆极化(RHCP)、左旋圆极化(LHCP)、H极化和V极化接收时,裸土和植被的散射特性进行了理论模拟。裸土散射特征的模拟采用镜像反射率模型和物理光学模型(PO)。对于植被部分,则采用镜像模型Spec-mimics(Specular-mimics)。在后向散射模型Mimics的基础上,加入散射角度(天顶角和方位角),同时修改由于散射角度加入而导致的相位矩阵、消光矩阵和地表反射矩阵、散射矩阵等,可以得到双站散射模型Bi-mimics。在其基础上,将角度设置为镜像,得到Spec-mimics模型。模拟结果表明,在10°～70°的入射角范围内,接收为LHCP极化时,只有在大的入射角(小接收机仰角)下会有散射值。线极化(H极化和V极化)则在整个角度范围内都有响应。而V极化在此角度范围内动态响应最大。因此如果在小入射角时,采用LHCP天线接收地表反射信号,极化损失较为严重;线极化在该入射角度范围内均可接收到地表反射信号,V极化由于对角度响应较好,因此更有利于地物特征研究。该理论模拟对接收机天线的极性设计提供了一定的理论指导。GNSS-R is a new promising remote sensing technique due to the advantages of low cost, small power and high spatial and time resolutions. GNSS constellation transmits the Right Hand Circular Polarization （RHCP） signals, which bring some useful information of the earth surface properties and reflect from it. They are received by the special designed GNSS-R receiver. Compared with the direct signals, the reflected ones are weaker and their polarizations have been changed, so a suitable receiver should be designed using the corresponding polarizations antenna to reduce polarized loss and increase the strength of received reflected signals. In principal, GNSSR is a kind of bistatic radar. This paper provides some research based on the microwave scattering model. Bare surface and vegetation theoretical simulations were taken as the transmitted signals is RHCP and the received ones are RHCP, LHCP, H and V polarizations. As for bare surface, specular reflectivity model and PO model are used, the Bistatic mimics （Bi-mimics） is developed based on the backscattering model Mimics （Michigan Microwave Canopy Scattering Model） by adding the azimuth and zenith scattering angles. The simulations indicate that there is scattering values only at large incident angles （ small elevation angles） as for the received polarization is LHCP. But linear polarizations exist for all the scattering angles（ 10° -70°）. Scattering response of V polarization is the largest one. Therefore, it is good for surface characteristics research. In theory, our theoretical simulations provide some useful information for receiver＇ s polarization design.

关 键 词：GNSS-R PO Bi—mimics Spec-mimics 极化 

分 类 号：P229[天文地球—大地测量学与测量工程]