Analysis of the abnormality of the ocean ambient noise vertical directionality caused by solitary waves

According to the two-dimension ambient noise model which combines wave number integral method (near field) and normal mode method (far field), the theoretical studies on the variation of the vertical array response to ambient noise in the region where the solitary waves exist are oriented. The reasons are analyzed theoretically for the "abnormal" phenomenon that notch in the horizontal direction of the vertical directionality of ambient noise becomes deeper when some solitary waves exist: when the solitary waves are close to the vertical array, the noise sources far from the solitary waves increase, the energy are converted from the lower order modes into the higher order modes, the contribution of higher order modes increases at the vertical array for ambient noise, the notch become deeper. When the vast-scale and multi-packets solitary waves exist, their region is relatively large. The influence of the changes of local eigenvalues and eigenfunctions in this region are remarkable. The attenuations of the lower order modes become faster, however, the higher ones become slower. The energy of higher order modes increases at the vertical array, so the noise notch become deeper no matter where the solitary waves are.