基于拟线性变换的海浪方向谱反演方法研究

海浪谱反演的交叉谱方法能有效降低斑点噪声并确定海浪传播方向,但从海浪谱到SAR交叉谱的非线性变换非常复杂,给海浪谱反演带来了分析和计算上的困难。依据从海浪谱到SAR交叉谱的非线性变换,给出了从海浪谱到交叉谱的拟线性变换,并利用海浪谱非负的约束条件,建立了一种基于该拟线性变换的反演方法。在引入海浪谱非负约束条件的情况下,反演过程中可以用拟线性变换代替非线性变换确定每次迭代的方向,不但能简化计算,并且能在反演精度不受影响的情况下,使反演过程更快、更稳定地收敛到最优海浪谱。

On the ocean wave spectrum inversion based on the quasi-linear transform

Although the ocean wave spectrum retrieval from SAR cross spectrum can avoid the speckle noise and the wave propagation direction ambiguity in image spectrum, the nonlinear transform from wave spectrum to SAR cross spectrum is too complex for the wave spectrum inversion in respect of analysis and computation. A quasi-linear transform is formulated based on the nonlinear one, and an inversion method applying the nonnegativity constraint of wave spectrum is derived. It is demonstrated that the quasi-linear transform could induce a very quick and stable inversion combined with the nonnegativity constraint.