浅海远程混响与海底散射强度
LONG-RANGE REVERBERATION AND BOTTOM SCATTERING STRENGTH IN SHALLOW WATER
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摘要: 利用浅海平均声场角度谱分析法,在海底散射的任意角度关系和浅海均匀层远程混响的距离关系之间建立了变换关系。与国外沿用的深海近程界面混响理论相比,多了多途传播修正因子K(公式18)。利用该变换关系式,由黄海、渤海、东海等5个海区的浅海远程混响资料,推得频率为0.8—4kHz,掠射角为2—10°的低频、小掠角海底散射强度。所得结果与国外深海直接测量的大掠角数据衔接较好。结果同时表明,大陆架高声速海底散射常数(μ)和角度指数(2n)不仅与海区、频率有关,而且与角度范围有关。在掠角很小时,海底散射强度随掠角减小比中等掠角时衰减更快。Abstract: According to the method of angular power spectrum for average sound field in shallow water, the transformation relation between arbitrary angle dependence of bottom scattering and the range dependence of long-range reverberation in shallow water homogeneous layer is established. As compared with the conventional model of boundary reverberation at short-range in deep sea, a multipath factor will be added. By using the transformation relation, the bottom baekscattering strength for the frequency band of 0.8-4.0 kHz and grazing angle range of 2-10 has been derived from shallow-water reverberation data at five locations in the Yellow Sea, the Bohai Sea and the East China Sea. It is shown that the bottom scattering constant (u) and angle index (2n) for high speed sediment of continental shelf depend not only on sea area and frequency, but also on angle range. For very low grazing angle the decay of bottom baekscattering strength with decreasing grazing angle is. more rapid than that for mediate grazing angle.