基于全球导航卫星系统(GNSS)反射信号的海冰检测模型的研究

It has been proved that bistatic scatteting of navigation reflection signal can be used to perform sea wind speed and wave height measurements, and can also be used to perform land soil moisture detection. However, there is no study on reflection signal off sea ice in the current domestic related research. In addition, it also requires more thorough verification to prove effective of navigation signal bistatic scatteting model on sea ice. Data from Global Navigation Satellite System Reflection (GNSS-R) signal off sea ice, which includes sea ice and ocean surface roughness and other useful information, can achieve sea ice area and thickness measurements. Advanced studies demonstrate the parametric ratio has an apparent evolution with the complex dielectric constant，the different normalized ratio of the reflected signal is closely linked with the sea ice formation and ablation procedure. This research is planned to analysis data from GNSS-R off sea ice, to prove that effective dielectric constant of ice and ice surface roughness are useful in sea ice detection. Because sea ice roughness has a distinctly different character than that of waves on a wind driven ocean surface, and salt of sea ice is also very different than that of ocean, bistatic scatteting from sea ice should differ from ocean bistatic scatteting, we can detect the difference between reflected signal characteristics on sea ice and ocean, to determine boundary between sea ice and ocean to estimate sea ice area. Because GNSS signal can penetrate the thin ice, reflection coefficient for thin ice might be affected by the underlying sea ice, establishing sea ice reflection-refraction model can estimate sea ice thickness. Because Young ice surface topography is different significantly from Old ice, establishing effective Young sea ice surface probability density function model (PDF) can decide sea ice age. That understanding the theory of GNSS-R off sea ice can provide theoretical basis to further realize the use of GNSS-R remote sensing off sea ice and arctic ice research.

基于导航反射信号的双基表面反射原理可以实现海风海浪和陆地土壤湿度的检测，但是基于导航反射信号的海冰检测，目前国内还没有相关的研究。此外，目前也需要验证反射信号的海冰双基反射模型的有效性。前期的研究显示双极化反射信号的幅度极化比和海冰表面的介电常数变化之间的联系,证明了幅度极化比值与海冰的形成和消融过程中海冰密集度有明显的关系。本项目拟通过分析GNSS 海冰反射信号的数据，证明冰块的有效介电常数和表面粗糙度是海冰检测中的有用信息。在已有的海面反射信号分析理论的基础上，确定冰面反射信号分析和阈值。调查海冰与海水的不同盐度的反射信号的特征， 确定海冰的临界线。建立海冰的反射-折射模型，确定海冰的厚度。建立初冰表面概率密度函数模型（PDF），确定海冰的冰龄。理解基于GNSS-R 的海冰反射的原理，为进一步利用GNSS-R 实现海冰遥感和极地海冰研究提供理论基础。

项目背景：.导航遥感理论作为一种新兴的遥感研究理论，目前在世界范围内进行着深入的研究，2012年美国NASA已把GPS反射信号的研究计划列入了最有发展前途的新技术项目之一。我国在这方面的研究还刚刚起步，与国际相关研究的技术差距很大。本项目针对上述迫切需要解决的GNSS反射信号的海冰监测问题，提出了一系列相关的新理论、新方法和新技术，在国内首先完成了基于GNSS反射的海冰监测理论研究，并且完成了国内首次GNSS反射信号的海冰监测实验，解决了GNSS的高精度组合定位，以及基于北斗反射信号的海冰监测，海面高度监测等理论难题，取得一系列理论研究和关键技术创新。..主要研究内容和关键数据：.1、导航卫星的厘米级精密定轨。提出了多卫星导航系统统一的时空基准、物理模型参数的估计等理论和方法，在国际上首次实现了四大卫星导航系统（北斗/GPS/GLONASS/Galileo）联合精密定位。.2、北斗/GPS系统反射信号海冰监测。以我国自主开发的北斗系统和美国GPS为多源微波信号发射源，突破了基于极化比的海冰GNSS-R监测技术，实现低成本、高时空分辨率，高密度连续观测的极地、渤海海冰遥感监测。.3、北斗/GPS反射信号海平面高度变化与风暴潮监测。突破了基于C/A码和载波相位测高的海平面高度反演技术，实现了GNSS-R在风暴潮监测的应用。.4、研制了我国首个具有自主知识产权的GNSS-R处理软件系统，改变了我国大规模、高精度GNSS 数据处理必须依赖于国外软件系统的被动局面。..科学意义：.1、成功应用“中欧伽利略科技合作计划”等国家级重大项目，解决了其核心和关键问题。.2、成功应用于极地、渤海海冰监测中，并推广到国内多家生产和研究单位。在海洋监测及地球科学研究等领域得到广泛应用，取得巨大的社会经济效益。.3、研发了GNSS-R处理系统；发表高水平研究论文20 余篇，为我国卫星导航领域培养大批高素质科技人才。