浅海平均混响强度的数值模拟

Numerical simulation of average reverberation intensity in shallow water

海中混响是回声探测的严重干扰。利用本文给出的混响模型可较快地计算分层海洋中平均混响强度的衰减规律及深度结构。 对于近程混响,由于海水非均匀性的影响较小,使用均匀层的射线方法计算。对于远程混响,使用简正波方法计算,它保持了平滑平均后的深度结构。在中等距离上两者能很好地衔接起来,由于考虑了复本征值对简正波入射场的影响,提高了计算精度,通过比较不同散射模型对混响强度计算的影响,提出以分离型二元散射模型作为混响数值模拟的基础,使能由界面反向散射系数估算二元后向散射系数,并大大简化混响强度的数值计算。

A reverberation model for estimating the average reverberation intensity in layered shallow water is presented. The reverbration intensify is calculated in terms of the ray method for short range and the normal-mode method for long range. The calculation accuracy has been improved by taking into account the effect of complex eigenvalue on the incident mormal-mode field. From the comparason between different scattering models it has been shown that the separable bi-static-backscattering model is acceptable. This makes it possible to calculate reverbration by using only the monostatic-backscattering coefficient and to save greatly the computing time.