X波段雷达海面回波谱宽特征研究
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摘要
海面电磁回波频谱宽度与海浪波高密切相关,可应用频谱宽度进行海浪有效波高反演。本文应用线性滤波法仿真出了海表散射面元在雷达视向上的投影速度,建立了回波谱宽模型,分析了雷达空间分辨率、回波时间序列长度及海洋环境参数等因素对频谱宽度的影响,同时还针对如何在实际观测过程中选择回波时间序列长度、观测方位角等参数进行了讨论。最后还将理论结果与CSIR-X波段雷达实测数据谱宽估计结果进行了比较。结果表明,剔除雷达噪声以及频率泄露的影响后,基于高斯分布标准偏差的谱宽估计方法所得结果与理论结果吻合很好,这从而证明了理论结果的可靠性。本文所得结果对海浪有效波高反演具有一定参考价值。
The spectral width of the electromagnetic scattering from sea surface is closely related to the SWH(significant wave height),and thus the spectral width can be used to retrieve the SWH.In this paper,the linear filtering method is employed to simulate the radial velocity of the orbit velocity of the each scattering element on sea surface.Based on the radial velocity,we establish a spectral width model,and analyze the influences of spatial resolution,time sampling length and SWH on spectral width.At the same time,we also discuss how to select the parameters such as time sampling length and the azimuth angle during the actual observation.Here,the theoretical results are compared with the estimated results based on the measured data required by the CSIR-X band radar.The comparisons demonstrate that the spectral width obtained by the estimation method based on Gaussian distribution standard deviation agree well with the theoretical results after eliminating the effects of radar noise and frequency leakage,which proves the reliability of the theoretical results.The results obtained in this paper have certain reference value for the retrieval of the SWH.
The spectral width of the electromagnetic scattering from sea surface is closely related to the SWH(significant wave height),and thus the spectral width can be used to retrieve the SWH.In this paper,the linear filtering method is employed to simulate the radial velocity of the orbit velocity of the each scattering element on sea surface.Based on the radial velocity,we establish a spectral width model,and analyze the influences of spatial resolution,time sampling length and SWH on spectral width.At the same time,we also discuss how to select the parameters such as time sampling length and the azimuth angle during the actual observation.Here,the theoretical results are compared with the estimated results based on the measured data required by the CSIR-X band radar.The comparisons demonstrate that the spectral width obtained by the estimation method based on Gaussian distribution standard deviation agree well with the theoretical results after eliminating the effects of radar noise and frequency leakage,which proves the reliability of the theoretical results.The results obtained in this paper have certain reference value for the retrieval of the SWH.
引文
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[18]Tsang L,Chan C H,Pak K,et al.Monte-Carlo simulations of large-scale problems of random rough surface scattering and applications to grazing incidence with the BMIA/canonical grid method[J].IEEE Transactions on Antennas and Propagation,1995,43(8):851-859.
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[21]葛凤翔,孟华东,彭应宁,等.杂波谱中心和谱宽估计方法[J].清华大学学报:自然科学版,2002,42(7):941-944.Ge Fengxiang,Meng Huadong,Peng Yingning,et al.Clutter central frequency and bandwidth estimation methods[J].Journal of Tsinghua University:Science and Technology,2002,42(7):941-944.
[2]Barrick D.First-order theory and analysis of MF/HF/VHF scatter from the sea[J].IEEE Transactions on Antennas and Propagation,1972,20(1):2-10.
[3]Zavorotny V U,Voronovich A G.Two-scale model and ocean radar Doppler spectra at moderate-and low-grazing angles[J].IEEE Transactions on Antennas and Propagation,1998,46(1):84-92.
[4]Toporkov J V,Brown G S.Numerical simulations of scattering from time-varying,randomly rough surfaces[J].IEEE Transactions on Geoscience and Remote Sensing,2000,38(4):1616-1625.
[5]Toporkov J V,Brown G S.Numerical study of the extended Kirchhoff approach and the lowest order small slope approximation for scattering from ocean-like surfaces:Doppler analysis[J].IEEE Transactions on Antennas and Propagation,2002,50(4):417-425.
[6]Wang Yunhua,Zhang Yanmin.Investigation on Doppler shift and bandwidth of backscattered echoes from a composite sea surface[J].IEEE Transactions on Geoscience and Remote Sensing,2011,49(3):1071-1081.
[7]Wang Yunhua,Zhang Yanmin,He Mingxia,et al.Doppler spectra of microwave scattering fields from nonlinear oceanic surface at moderate-and low-grazing angles[J].IEEE Transactions on Geoscience and Remote Sensing,2012,50(4):1104-1116.
[8]Wang Yunhua,Zhang Yanmin,Guo Lixin.Microwave Doppler spectra of sea echoes at high incidence angles:influences of large-scale waves[J].Progress in Electromagnetics Research B,2013,48:99-113.
[9]Walker D.Experimentally motivated model for low grazing angle radar Doppler spectra of the sea surface[J].IEEE Proceedings-Radar,Sonar and Navigation,2000,147(3):114-120.
[10]Rozenberg A D,Quigley D C,Melville W K.Laboratory study of polarized microwave scattering by surface waves at grazing incidence:the influence of long waves[J].IEEE Transactions on Geoscience and Remote Sensing,1996,34(6):1331-1342.
[11]Rozenberg A D,Quigley D C,Melville W K.Laboratory study of polarized scattering by surface waves at grazing incidence.I.Wind waves[J].IEEE Transactions on Geoscience and Remote Sensing,2002,33(4):1037-1046.
[12]Corretja V,Meslot V,Kemkemian S,et al.Statistical analysis on sea clutter Doppler properties in X-band for low grazing angles[C]//2017 IEEE Radar Conference(RadarConf).Seattle,WA,USA:IEEE,2017.
[13]张金鹏,张玉石,李清亮,等.基于不同散射机制特征的海杂波时变多普勒谱模型[J].物理学报,2018,67(3):106-116.Zhang Jinpeng,Zhang Yushi,Li Qingliang,et al.A time-varying Doppler spectrum model of radar sea clutter based on different scattering mechanisms[J].Acta Physica Sinica,2018,67(3):106-116.
[14]Fiche A,Angelliaume S,Rosenberg L,et al.Statistical analysis of low grazing angle high resolution X-band SAR sea clutter[C]//2014 International Radar Conference.Lille,France:IEEE,2014.
[15]Watts S,Rosenberg L,Bocquet S,et al.Doppler spectra of medium grazing angle sea clutter;part 1:characterisation[J].IET Radar,Sonar&Navigation,2016,10(1):24-31.
[16]Wang Yunhua,Li Huimin,Zhang Yanmin,et al.The measurement of sea surface profile with X-band coherent marine radar[J].Acta Oceanologica Sinica,2015,34(9):65-70.
[17]Wang Yunhua,Li Qun,Zhang Yanmin.A statistical distribution of quad-pol X-band sea clutter time series acquired at a grazing angle[J].Acta Oceanologica Sinica,2018,37(3):94-102.
[18]Tsang L,Chan C H,Pak K,et al.Monte-Carlo simulations of large-scale problems of random rough surface scattering and applications to grazing incidence with the BMIA/canonical grid method[J].IEEE Transactions on Antennas and Propagation,1995,43(8):851-859.
[19]Elfouhaily T,Chapron B,Katsaros K,et al.A unified directional spectrum for long and short wind-driven waves[J].Journal of Geophysical Research:Oceans,1997,102(C7):15781-15796.
[20]Keller W C,Plant W J,Petitt R A Jr,et al.Microwave backscatter from the sea:Modulation of received power and Doppler bandwidth by long waves[J].Journal of Geophysical Research:Oceans,1994,99(C5):9751-9766.
[21]葛凤翔,孟华东,彭应宁,等.杂波谱中心和谱宽估计方法[J].清华大学学报:自然科学版,2002,42(7):941-944.Ge Fengxiang,Meng Huadong,Peng Yingning,et al.Clutter central frequency and bandwidth estimation methods[J].Journal of Tsinghua University:Science and Technology,2002,42(7):941-944.