摘要
冲绳海域地形复杂且冬季存在较强的黑潮海洋锋,利用数值实验研究斜坡地形和海洋锋同时存在时由浅海至深海的声传播特性。海洋模式数值预报环境数据表明,分布于冲绳海槽斜坡上方的海洋锋导致该海域上层水体声速存在水平变化,纬度越高,水平变化越大。利用抛物方程声场模型计算声传播损失,通过简正模态分析存在表面声道的环境中声能量分布,利用声线轨迹图解释海底斜坡和海洋锋对声传播的影响。结果表明:声源频率低于表面声道截止频率时,声传播主要受海底地形影响;声源频率高于表面声道截止频率时,位于表面声道内的声源激发的声能量主要在表面声道传播,部分声能量从表面声道泄漏沿斜坡向深海传播,位于表面声道深度以下的声源激发的声能量主要沿斜坡向深海传播,斜坡地形导致表面声道下方至共轭深度这一深度范围呈现为声影区,海洋锋的存在可导致表面声道传播损失变化明显,影响程度与声源深度有关。
The topography in the Okinawa Sea is usually complex,and there is a strong Kuroshio front in winter.Characteristics of sound field,running from shallow to deep water across slope topography and across the front,are analyzed by numerical experiments.The environmental data provided by the Hybrid Ocean Model show that the Kuroshio front is above the slope of the Okinawa trough.Moreover,sound speed of the upper water varies in the horizontal direction,and the horizontal sound-speed change increases with the latitude increasing.The transmission loss is calculated by the parabolic-equation acoustic model.The distribution of sound energy in the environment with the existence of surface duct is analyzed by normal modes.Effects of the topography and a front on sound propagation are explained using ray diagrams.It shows that the sound propagation is mainly influenced by the topography when the frequency of source is lower than the cut-off frequency of surface duct.When the frequency of source is higher than the cut-off frequency of surface duct,the sound energy excited by the source located in the surface duct mainly propagates around the surface channel,and part of sound energy leaking from the surface duct transmits along the slope to the deep water.The sound energy excited by the source located below the surface duct mainly propagates along the slope to the deep water.The sound field in the depth range from the bottom of the surface duct to the conjugate depth appears as a sound shadow area due to the effect of slope bottom.It is also observed that the existence of a front can lead to significant differences of the transmission loss in surface duct at some depths of sound source.
作者
殷丽君
张林
孙雪海
段嘉希
笪良龙
YIN Lijun;ZHANG Lin;SUN Xuehai;DUAN Jiaxi;DA Lianglong(Navy Submarine Academy,Qingdao 266199;Qingdao National Laboratory for Marine Science and Technology,Qingdao 266237)
出处
《声学学报》
EI
CAS
CSCD
北大核心
2023年第4期802-810,共9页
Acta Acustica
基金
国家重点研发计划项目(2021YFC3100900)资助。
关键词
黑潮海洋锋
表面声道
声传播
海底地形
Kuroshio front
Surface duct
Acoustic propagation
Topography
