利用角度分集SAR反演海洋流场与风场

The sea surface current vector and the wind vector are the most basic and important ocean dynamical parameters in the ocean and atmosphere research field. These parameters are of extremely vital significance in their research on ocean and climate change, sea transportation safety, marine engineering, military activities and so on. Although technologies for satellite remote sensing of sea surface wind field are relatively mature, there still exist some difficulties in offshore high-resolution wind field remote sensing. Besides, up to now, remote sensing of sea surface current field has not been solved well. In view of the aforementioned points, it is necessary to carry out research on the technologies for high-resolution remote sensing of the sea surface current vector and the wind vector. In this research, we will first propose a novel radar system, named angle-diversity SAR, aimed at the retrieval of sea surface current field and sea surface wind field. From the point of view of radar system design and practical applications (e.g., sea surface wind vector and current vector retrievals, etc.), radar system parameters, including the number of beam pointing angles, the optimal angles between different beams, the radar transmission power, and the suitable PRF, will be determined. The imaging theory and method of the angle-diversity SAR will be investigated in detail. The basic principles of sea surface current vector and wind vector retrieval associated with the angle-diversity SAR will be studied using numerical simulations. Afterwards, the algorithms for retrieving the sea surface current field, the sea wind field, as well as the joint current and wind fields, will be developed respectively. The factors that influence the inversion accuracy of the marine dynamic parameters will be studied. The relations between the inversion accuracy and the angle between SAR beams will be established.

海表面流矢量和海面风矢量是海洋和气象领域中诸多过程中最基本、最重要的要素，它们对海洋和气候变化研究、海上交通运输安全、海洋工程开发、军事活动等都有着十分重要的意义。尽管卫星遥感海面风场技术较为成熟，但对于近岸高分辨率的风场遥感还存在一定的困难，另外海表流场遥测一直未能很好地解决，因此有必要开展高分辨率获取海面流矢量和风矢量遥测方法研究。本研究将首次提出角度分集SAR系统，试图从雷达系统设计和应用需求（风场反演、流场反演等）的角度出发，确定波束指向角度的个数以及波束间夹角大小的最优值、系统的发射功率以及适合的PRF等雷达系统参数，系统研究角度分集SAR成像理论和方法；利用数值仿真技术开展角度分集SAR海面流场与风场反演的基本原理与方法研究，建立海面流场、风场反演算法及流场与风场联合反演算法；分析和研究影响海洋动力参数反演精度的因素，建立其反演精度与SAR波束之间夹角大小的关系。

海表面流矢量和海面风矢量是海洋和气象领域中诸多过程中最基本、最重要的要素，尽管卫星遥感海面风场技术较为成熟，但对于近岸高分辨率的风场遥感还存在一定的困难，另外海表流场遥测一直未能很好地解决，因此有必要开展高分辨率获取海面流矢量和风矢量遥测方法研究。本课题主要开展了新体制测流合成孔径雷达的基础理论和数值模拟研究，提出了基于角度分集的星载SAR系统为一全新的星载SAR体制，在海洋环境探测领域将具有非常好的应用前景。相比于传统的海面流场反演手段，本发明提出的基于角度分集的海洋流场星载SAR系统能够反演全球范围的海洋流场，全面了解海流的时空变化。顺轨干涉SAR方法以及单天线SAR多普勒中心偏移方法只能得到海流的径向速度而无法得到完整的二维速度矢量，本课题提出的基于角度分集的星载SAR系统很好地解决了这一难点问题，能够同时得到海流的径向速度信息与方位向速度信息。同时，本课题提出了基于逆Omega-K算法的海面要素SAR原始数据仿真方法，仿真得到的海面要素SAR原始数据中同时包含了各种海面调制（倾斜调制、水动力调制、波浪轨道径向速度调制以及像素单元内速度随机分布调制）以及海流速度信息，简单易行且运算量较小。另外多普勒中心估计精度的估算不仅对评价已有SAR的海流测量精度有重要意义，而且对新体制雷达的研制以及系统参数设计具有不可替代的作用，提出了新的多普勒中心估计方法。海面风矢量是海洋气象学中的重要物理参数，是海洋和气象领域中诸多过程中最基本、最重要的要素，本课题提出了风场-流场联合反演的新思路，能够同时获取海面流场和海面风场，对后续研究具有指导意义。本项目成果对海洋和气候变化研究、海上交通运输安全、海洋工程开发、军事活动等都有着十分重要的意义。