Siderius Martin, Li Jie, Gerstoft Peter
Department of Electrical and Computer Engineering, Portland State University, Portland, Oregon 97201, USA.
Noiselab, Scripps Institute of Oceanography, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093, USA.
J Acoust Soc Am. 2018 Feb;143(2):1182. doi: 10.1121/1.5024332.
Seismic interferometry recovers the Green's function between two receivers by cross-correlating the field measured from sources that surround the receivers. In the seismic literature, it has been widely reported that this processing can produce artifacts in the Green's function estimate called "spurious multiples" or the "virtual refracted wave." The spurious multiples are attributed to the head wave and its multiples and travels in the seabed. The head wave phenomenon is shown to be observable from both controlled active sources and from ocean ambient noise and for both vertical and horizontal arrays. The processing used is a generalization of the passive fathometer to produce cross-beam correlations. This passive fathometer is equivalent to the seismic interferometry techniques for delay and sum beamforming but not for adaptive beamforming. Modeling and experimental data show the head wave is observed in ocean noise and can be used to estimate the seabed sound speed.
地震干涉测量法通过对从围绕接收器的源测量的场进行互相关来恢复两个接收器之间的格林函数。在地震文献中，已广泛报道这种处理会在格林函数估计中产生被称为“虚假多次波”或“虚拟折射波”的伪像。虚假多次波归因于首波及其多次波，并在海床中传播。首波现象在受控有源源和海洋环境噪声中均可观测到，并且对于垂直和水平阵列都能观测到。所使用的处理方法是对被动测深仪的一种推广，以产生交叉波束相关性。这种被动测深仪在延迟和求和波束形成方面等同于地震干涉测量技术，但在自适应波束形成方面则不然。建模和实验数据表明，在海洋噪声中可以观测到首波，并且可用于估计海床声速。
