高频声学流速层析研究

海陆界面是人类海洋开发活动最为集中的区域,流速在线监测对于其物质通量和生态系统演变极其重要.本文研究了小尺度海陆界面的高频声学流量层析,基于声互易传输原理构建河流平均流速和流量的声学反演算法,并在漳州九龙江海陆界面开展验证实验.应用高频换能器(中心频率为60 kHz,带宽为40–80 kHz)进行互易收发.根据声速剖面和水下地形测量,开展射线声学数值模拟,揭示高频声传播规律.实验测量表明,声信号具有较高的信号幅度和互相关峰值,能够反演河流的平均流速和流量,并对台风“海贝思”期间河流平均流速和流量实现动态监测.研究表明,高频声层析可应用于海陆界面水动力研究、水文测量、洪峰和强降雨等极端事件的监测与预报等.

Study of high-frequency acoustic current tomography

The sea-land interface is the most concentrated region of human marine development activities,and online monitoring of river current is very important for material flux and ecosystem evolution.In this study,the high-frequency acoustic current tomography of sea-land interface was studied.Based on the principle of acoustic reciprocity,the acoustic inversion algorithm of current was investigated.The experiment was carried out on the Jiulongjiang sea-land interface in Zhangzhou.The high-frequency transducer,with a center frequency of 60 kHz and bandwidth of 40–80 kHz,was used.According to the sound speed profile and underwater topographic survey,ray acoustic simulation was performed to reveal high-frequency sound propagation.The experimental results showed that the acoustic signal has high-signal amplitude and peak value of cross-correlation,which can be used to reconstruct the current of the river.Real-time monitoring of the river current during the typhoon“haibeisi”was achieved.The results showed that high-frequency acoustic tomography can be applied to the study of hydrodynamics of sea-land interface,hydrological measurement,and monitoring of extreme events,such as flood peak and heavy rainfall.