基于S波段多普勒雷达的海浪谱及海浪参数反演算法研究

There are two important scientific problems in the field of radio ocean remote sensing: the interaction mechanism of electromagnetic wave and rough ocean surface, wave and current estimation algorithms. With the shore-based multi-beam S-band Doppler radar, the program studies the interaction of microwave and ocean surface, and builds the multi-scale ocean wave scattering model based on the double scale wave model for microwave, which uses the methods including theoretical research, numerical simulation and analysis of experimental data from radars. Both seaside measuring and comparison-validation experiments are planned to collect measured echo data of different sites, seasons, range resolutions, incidence angles and directions of illumination, which is used to analyze the features of Doppler spectra in time-domain, frequency-domain and space-domain. e.g. time Doppler spectra, intensity and bandwidth of Doppler spectra, Doppler shift etc.. Then further analyze the relationship of radar's operating conditions and its measurement accuracy, improve the inversion theories of ocean wave spectra and current. For phenomena like wave breaking, offshore oil spillage and moving targets which cause changes in Doppler spectra, methods such as characteristic identification, classification, separation, and correction are applied. It is significant to put forward universal controlling means and evaluation criterion of data-quality, and design algorithms for distinguishing and processing exceptional radar echoes in order to diminish their adverse effects on the inversion accuracy of wave spectra and current. It can provide more accurate data for the marine scientific research.

电磁波与海洋粗糙面的相互作用机理、海浪参数反演算法是无线电海洋环境监测领域的2个重要科学问题。本项目以自主研制的岸基多波束S波段多普勒雷达为观测平台，采用理论研究、模拟仿真以及国内外雷达实测数据分析相结合的方法，研究微波与海洋表面相互作用机理，建立多尺度海浪电磁散射模型。开展海边观测和对比验证试验，采集不同地点、不同季节、不同距离分辨率、不同入射角、不同照射方向的海洋回波数据，根据其多普勒谱的时域、频域及空域特征，分析雷达工作条件与探测精度的关系，完善S波段多普勒雷达的海浪谱和海流反演理论和算法，提高雷达的海浪反演精度；针对波浪破碎、海面溢油、移动目标等现象在回波多普勒谱中引起的特征变化，采取特征识别、分类、分离或修正等措施，提出普适的数据质量控制方法和评价依据，减小其对海浪谱和海流反演精度的不利影响，为海洋科学研究提供更准确的数据资料。

本课题围绕提高S波段多普勒测波雷达的海浪反演精度进行了深入研究，开展了多次现场比测实验，研究实现了基于频移迭代的多普勒谱中心频率估计算法和基于超射特征的风涌浪分离算法，并完成了对于非线性海洋表面的建模与回波多普勒谱仿真，改善S波段多普勒雷达的测量性能并丰富测量结果。同时在目标与破碎波检测、风涌浪分离、非线性散射机理研究与船载S波段雷达走航观测方面形成了重要研究成果。在目标检测方面，通过频域滑窗的方式有效检测了回波多普勒谱中的目标信号并加以剔除；在破碎波检测与分离方面，提出了基于经验模态分解的破碎波检测与抑制算法。对目标信号和破碎波的抑制处理进一步提高了S波段多普勒雷达的海浪参数测量精度。另外，对走航观测条件下的回波多普勒谱进行了仿真研究并提出了基于空间采样的海浪参数反演算法，岸基平台实验和船载走航观测实验都证实了空间算法的有效性，拓展了S波段多普勒雷达系统的应用范围，为海洋科学研究提供更准确的数据资料。