基于立体摄影数据的二维海浪方向谱反演技术研究

Two-dimensional Wave Direction Spectrum Inversion Based on Stereo Photography Data

  • 摘要: 立体摄影技术可实现三维海浪的连续观测。然而,目前基于立体摄影海浪观测数据开展二维海浪方向谱估计的研究却相对匮乏,从而束缚了立体摄影技术在海洋观测中的进一步深入应用。鉴于此,本文基于中国海洋大学微波遥感实验室开发的立体摄影海浪观测系统,并结合海浪方向谱阵列测量的扩展本征矢方法,系统性研究了基于立体摄影海浪观测数据反演二维海浪方向谱的可行性,并分析了不同海面采样点阵列排列方式、采样点间距及观测误差等因素对二维海浪方向谱反演结果的影响。立体摄影实测海浪数据反演结果显示:阵列中采样点间距小于1/3波浪的波长,海面采样点阵列排列方式为五边形时可得到较好的海浪方向谱反演结果。通过将立体摄影数据反演所得二维海浪方向谱与Signature1000型声学多普勒波浪流速剖面仪(Acoustic Doppler Wave and Current Profiler, AWAC)测量结果进行比较,结果显示二者具有较高的相关性和良好的一致性。具体而言,立体摄影所得有效波高、平均波向和AWAC测量的有效波高、平均波向的相关系数分别为0.988和0.983,平均偏差分别为0.029 m和0.010°,均方根误差分别为0.089 m和8.844°。

     

    Abstract: Stereo photography enables continuous observation of three-dimensional ocean waves. At present, however, there is a lack of research on two-dimensional wave direction spectrum estimation based on stereo photography wave observation data, which restricts further application of stereoscopic technology in ocean observation. In view of this situation, based on the stereoscopic wave observation system developed by the Microwave Remote Sensing Laboratory of Ocean University of China and combined with the extended eigenvector method of wave direction spectrum array measurement, the feasibility of inversion of two-dimensional wave spectrum based on stereo photography wave observation data is systematically studied, and the influence of factors such as array arrangement, sampling point spacing, and observation errors of different sea surface sampling points on the two-dimensional wave direction spectrum inversion results is analyzed. The inversion results of wave data measured by stereoscopic photography show that better wave direction spectrum inversion results can be obtained when the distance between sampling points in the array is less than 1/3 wave wavelength and the array of sampling points is pentagonal. By comparing the two-dimensional wave direction spectrum obtained from the stereo photography data with the measurements of the Signature1000 Acoustic Doppler Wave and Current Profiler (AWAC), it is evident that the results obtained from the stereo photography are in good alignment with the measurements of AWAC. Specifically, the correlation coefficients for the effective wave height and mean wave direction obtained from stereo photography and those measured by the AWAC are 0.988 and 0.983, respectively, with average bias of 0.029 m and 0.010°, respectively, the root mean square errors are 0.089 m and 8.844°, respectively.

     

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