一种声速剖面展开的正交基函数获取方法

A methodology to achieve the basis for the expansion of the sound speed profile

为了评估经验正交函数(Empirical Orthogonal Functions)在声速剖面的声学反演应用中的可靠性和适用性,降低声速剖面基函数的获取对样本数据的依赖性,提出了一种声速剖面展开的正交基函数的获取方法.该方法通过分析引起声速剖面变化的海洋动力学过程,利用动力学方程求解得到的水动力简正波(Hydrodynamic Normal Modes)来给出声速剖面展开的基函数.HNMs方法获得的声速剖面正交基函数与EOFs方法的结果非常吻合,且对样本数据的依赖性小。HNMs方法物理意义清晰,能够给出决定声速剖面正交基函数的物理参数,使评估经验正交函数的准确性和适用性成为可能。

In order to evaluate the reliability and applicability of the Empirical Orthogonal Functions （EOFs） applied in the acoustic inversion of sound speed profile （SSP） and reduce the dependence of SSP＇s basis on sample data, a theoretical methodology was proposed for the achievement of the basis in the expansion of SSP. By analyzing the oceanographic dynamics which was the cause of the SSP＇s change, a theoretical basis named the Hydrodynamic Normal Modes （HNMs） was derived from these dynamics equations. The orthogonal basis for SSP derived from HNMs was as good as that from EOFs, while it had less dependence on sample data. HNMs method had a clear physical meaning, and could tell the physical parameter determined the basis for SSP, which made it possible to analyze and evaluate the veracity and applicability of EOFs.