基于优化理论的高频地波雷达海浪参数反演
Optimization metho d for extracting o cean wave parameters from HFSWR
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摘要: 针对从高频地波雷达海洋回波多普勒谱反演海浪参数的非线性积分方程,采用线性化近似可以转化为线性积分方程,类似于第一类Fredholm积分方程。文中采用数值方法将线性积分方程转化为二次型最优化问题,并采用共轭梯度法来求解。针对海浪参数的非负先验特性,在迭代过程中,加入非负约束项对共轭梯度法进行了改进。在单部雷达和双部雷达情况下进行正演数值模拟,然后用模拟数据添加不同信噪比的随机噪声进行海浪参数反演,无论是单峰海浪谱还是有两个传播方向的双峰谱反演结果均表明了本文提出的算法在不同信噪比下的有效性。Abstract: The principle of Doppler spectra detected by HFSWR (high-frequency-surface-wave radar) is given by a nonlinear integral equation from which can be extracted ocean wave parameters. By linearization, the equation can be transferred into a first kind of Fredholm integral equation approximately and can be displayed in a quadratic form. Conjunction gradient (CG) method is proposed to solve the optimization problem. Non-negative restriction is introduced to improve the involved CG algorithm and fit to the priori knowledge so that the ocean wave parameter is non-negative. Validity and accuracy of the proposed method are demonstrated by numerical simulation with different noise levels at one site and two sites.
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