Predicting Method for Transformation of Infragravity Waves with Interferometric Green's Functions

本文提出了一个估算短重力表面波激发的亚重力波高度的随机强迫模式。该模型包括一个波动方程的亚重力波的外力项，由于短重力波的压力扰动。得到了波动方程的解析解，并估算了亚重力波的地表高程均方根值。均方根值正比于重力短波的-2阶谱矩m_1的平方根<-2>，也正比于重力短波的波高与峰值波周期或有效波周期的乘积。本文将地震干涉测量中的绿色函数方法应用于亚重力波的波形估计。结果表明，当外力为不相关噪声源时，可通过记录的互相关反演两点间的绿色函数。用绿色函数估计了亚重力波的波形，并与实测数据进行了比较。他们之间的协议显示相当不错。

A stochastic forcing model has been developed to estimate the heights of infragravity waves excited by short gravity surface waves. The model includes a wave equation for infragravity waves with the external force term due to pressure disturbances by short gravity waves. The analytical solution of the wave equation was obtained, and the root-mean-square value of the surface elevation of infragravity waves was estimated.. The rms value is proportional to the square root of the spectral moment of -2 order, m_<-2>, of short gravity waves, which is also proportional to the product of the wave height and the peak wave period or the significant wave period of short gravity waves.The propagation of infragravity waves in intermediate water depths near and in a port is investigated with field observations. A Green function method which is used for seismic interferometry is applied to estimate wave profiles of infragravity waves. It is shown that when external forces are uncorrelated noise source, Green functions between two points can be retrieved by taking cross-correlation of records. The wave profiles of infragravity waves are estimated with the Green function and compared with the measured data. The agreement between them shows fairly good.