Radio Wave Scattering from Rough Surfaces -- Theory and Application to Ocean Remote Sensing with HF and Marine Radar

在过去的40年里，各种雷达在新型海洋遥感应用中变得重要。在这方面，已成功地使用了在3至30兆赫频带（波长10至100米）工作的高频表面波雷达，最近，也同样使用了频率约为8至12千兆赫（波长约为4至10厘米）的X波段航海雷达。 对于高频信号，海洋表面充当良导体，并且所传输的辐射远超出视线地平线，从海洋波浪和物体（例如，在表面上和表面附近的船舶、冰和冰山以及低空飞行的飞机）散射。自20世纪80年代初以来，纪念大学（MUN）的研究人员在NSERC，海上石油工业和各种政府机构的支持下，一直在解决与模拟这种多方面散射过程相关的挑战。继续开发这些模型对于加强从接收信号中提取信息的技术至关重要，这些信息包括波高、表面流和目标速度。 自2000年以来，雷达小组继续将其分析从单基地情况（发射机和接收机共置）扩展到包括双基地模式，在双基地模式中，雷达发射机和接收机可能相距很远。此外，正在进行的工作包括在移动平台上安装雷达天线和检查电离层信号污染，这些工作有可能以较低的成本扩大覆盖范围，同时提高提取算法的稳健性。 目前，高频地波雷达的研究正在通过改进X波段雷达测量海洋表面流、风和波浪的技术而得到加强。在X波段，表面波分量并不显著，雷达作用距离基本上限于测线。然而，所提供的数据的分辨率比高频高得多，可用于提供高频系统通常提供几平方公里平均数的区域的海洋表面的精细尺度特征（平方米量级）。 就高频地波雷达而言，由于国家空间环境研究中心和其他有关方面的支持，加拿大已成为雷达遥感理论和应用方面的世界领先者。在过去的三十年里，模拟联合国的工作大大增加了这一领域的知识体系，同时导致了国际技术的出口。与政府、工业界和科学界合作，很有可能扩大这些系统的遥感能力，并支持涉及海洋雷达的较新倡议。预计在这一建议范围内开展的工作将继续吸引科学界和工业界以及海事安全方面的关注。

Over the last 40 years, radars of various kinds have become important in novel ocean remote sensing applications. In this context, high frequency surface wave radars (HFSWRs), operating in the 3 to 30 MHz frequency band (wavelengths of 10 to 100 metres), have been successfully employed, and, more recently, X-band nautical radars, ranging in frequency from about 8 to 12 GHz (wavelengths of about 4 to 10 centimetres), have been similarly used. For HF signals, the ocean surface acts as a good conductor, and the transmitted radiation travels well beyond the line-of-sight horizon, scattering from ocean waves and objects, such as ships, ice and icebergs, and low-flying aircraft, on and near the surface. Since the early 1980s, Memorial University (MUN) researchers, supported by NSERC, the offshore oil industry and various government agencies, have been addressing the challenges associated with modelling this many-faceted scattering process. The continued development of these models is critical to enhancing techniques used to extract information, such as waveheights, surface currents and target velocities, from the received signals. Since 2000, the radar team continues to extend its analysis from the monostatic case (co-location of transmitter and receiver), to include the bistatic mode, in which the radar transmitters and receivers may be widely separated. Also, ongoing work, involving mounting the radar antennas on moving platforms and the examination of ionospheric signal contamination, has the potential of increasing coverage at a reduced cost while improving the robustness of extraction algorithms. Currently, the HFSWR research is being augmented by the development of improved techniques for measuring ocean surface currents, winds and waves with X-band radar. At X-band, the surface wave component is not significant and the radar range is essentially limited to line-of-site. However, the data provided is of a much higher resolution than at HF and may be used to provide fine-scale features (on the order of square metres) of the ocean surface in regions where HF systems typically provide averages over several square kilometres. In the case, of HFSWR, due to support from NSERC and other interested parties, Canada has become a world leader in both theoretical and applied aspects of radar remote sensing. Over the last three decades, the MUN work has added significantly to the body of knowledge in this field, while leading to the export of the technology internationally. In collaboration with government, industry and the scientific community, there is very good potential to extend the remote sensing capabilities of these systems as well as to support the newer initiatives involving marine radar. It is expected that the work undertaken under the umbrella of this proposal will continue to attract interest from the scientific and industrial communities as well as those involved in maritime security.