南海北部内波作用下声散射层垂直迁移特征研究  

Study on the vertical migration characteristics of the acoustic scattering layer under the influence of internal waves in the northern South China Sea

作　　者：毕伟传 梁楚进 蔺飞龙 崔子健 汤俊辉 Bi Weichuan;Liang Chujin;Lin Feilong;Cui Zijian;Tang Junhui(State Key Laboratory of Satellite Ocean Environment Dynamics,Second Institute of Oceanography,Ministry of Natural Resources,Hangzhou 310012,China;School of Ocean Science,Nanjing University of Information and Technology,Nanjing 210044,China;School of Ocean Science,Zhejiang University,Hangzhou 310058,China)

机构地区：[1]自然资源部第二海洋研究所卫星海洋环境动力学国家重点实验室,浙江杭州310012 [2]南京信息工程大学海洋科学学院,江苏南京210044 [3]浙江大学海洋学院,浙江杭州310058

出　　处：《海洋学报》2024年第8期37-49,共13页

摘　　要：利用深海潜标搭载的声学多普勒流速剖面仪得到的后向散射强度,研究了南海北部声散射层的昼夜垂直迁移和内孤立波对其的影响。观测结果表明:受浮游动物影响,声散射层主要表现为“昼沉夜浮”,日出前约1 h至日出期间向下移动,日落至日落后约1 h期间向上移动,平均迁移速度为4.7 cm/s(上移)和5.8 cm/s(下移)。此外,经过观测海域的内孤立波引起一对先向下后向上的垂向流,最大垂向流速超过50 cm/s,导致声散射层发生数十至上百米的起伏,海洋上层的声学后向散射强度在内孤立波波谷处达到极大值。进一步的研究显示日间出现内孤立波垂向流速与深度平均后向散射强度变化幅度相关性比夜间的内孤立波高。在两种类型波动引起的垂向流速相当时,日间的深度平均后向散射强度变化幅度通常大于夜间。Based on the Acoustic Doppler Current Profiler carried by deep-sea moorings,we investigated the diel vertical migration of the acoustic scattering layer and the impact of internal solitary waves on it in the northern South China Sea.The observational results reveal that the acoustic scattering layer,influenced by zooplankton,ascends to shallower depth within approximately an hour after sunset,remains there throughout the night,then migrates to the deeper depth within about an hour before sunrise.The average migration velocities are 4.7 cm/s(upward)and 5.8 cm/s(downward).Additionally,internal solitary waves observed in the region induce a pair of downward and upward currents,with maximum vertical velocities exceeding 50 cm/s,leading to fluctuations of tens to hundreds of meters in the acoustic scattering layer.The acoustic backscattering strength of the ocean’s upper layer reaches its maximum value at the troughs of internal solitary waves.Further research indicates that the daytime internal solitary waves exhibit a stronger correlation between the vertical velocity and the depth-averaged backscattering strength variation compared to the nighttime internal solitary waves.When the vertical velocities induced by both types of waves are equal,the depth-averaged backscattering strength variations during the day are typically greater than those at night.

关 键 词：声学多普勒流速剖面仪 内孤立波 声散射层 昼夜垂直迁移 南海 

分 类 号：P733.2[天文地球—物理海洋学]