河口海岸区域的高频声层析研究

发布时间：2018-10-04 23:20

【摘要】：声学技术在海洋环境观测中具有重要的作用。河口海岸区域的高频声层析技术为观测河口海岸区域的温、盐、流等环境参数提供了有效声学手段。近年来,亚太地区的沿海、河口及边缘海的沿岸声层析观测成为研究热点。然而,以往的沿岸声层析研究主要关注10km尺度的中频海洋声层析观测,以及边缘海区域的中低频声层析研究。而关于河口海岸区域的高频声层析工作开展较少。本文主要围绕河口海岸区域的高频声层析问题,进行了理论探讨、数值模拟、设备研发和实验观测等多方面的研究。首先,本文介绍和整理了河口海岸区域温流反演的互易传输模型。其次,基于互易传输模型,进行了河口海岸区域的高空间分辨率声层析理论研究,提出了网格化的高空间分辨率反演方法。并以厦门嵩屿电厂海域的卫星遥感海面温度数据和区域海洋模型的流场数据,对厦门嵩屿电厂海域这一温度变化显著,流场分布较为复杂的典型河口海岸区域的二维高空间分辨率温度、流场声层析反演进行了理论研究。讨论了声站数、测量误差与反演精度的关系,并在高分辨率、高阶情况下对广泛使用的傅里叶级数模型进行了数值研究。结果表明,声层析理论研究精确重建了40m高空间分辨率的声速、温度分布和流场。在理论研究的工作上更进一步,研发了河口海岸区域的15kHz高频声层析观测设备。基于NI数据采集卡和LabVIEW编程,利用GPS的硬件定时实现了微秒精度的时间同步,实现了传播时间的准确测量。最后,在厦门鹭江海峡进行了高频声层析观测实验。实验精确测量了鹭江海峡的声互易传播时间,获得了鹭江海峡的声速变化和流速变化。对鹭江海峡潮流的测量较为准确,符合以前的观测与模型数据。在实验中,对调制伪随机码长度,接收信号信噪比以及流速测量误差进行了比较研究。本文通过理论与实验研究表明,河口海岸区域的高频声层析技术为本区域的高分辨率温度、声速分布和海流测量提供了有价值的声学方法。
[Abstract]:Acoustic technology plays an important role in marine environmental observation. The technique of high frequency acoustic tomography in estuarine and coastal areas provides an effective acoustic means for observing the environmental parameters such as temperature, salt and current in estuarine and coastal areas. In recent years, coastal acoustic tomography observations of coastal, estuarine and marginal seas in the Asia-Pacific region have become a hot topic. However, previous studies of coastal acoustic tomography mainly focus on the 10km scale of mid-frequency ocean acoustic tomography observation, and the marginal sea area of mid-low frequency acoustic tomography research. However, there is less work on high frequency acoustic tomography in estuarine and coastal areas. This paper focuses on the problems of high frequency acoustic tomography in estuarine and coastal areas, including theoretical research, numerical simulation, equipment development and experimental observation. Firstly, this paper introduces and arranges the reciprocal transmission model for the inversion of the temperature current in the estuarine and coastal regions. Secondly, based on the reciprocal transmission model, the high spatial resolution acoustic tomography theory of estuarine and coastal area is studied, and a high spatial resolution inversion method based on grid is proposed. Based on the satellite remote sensing sea surface temperature data of Songyu Power Plant in Xiamen and the current field data of the regional ocean model, the temperature variation in the sea area of Songyu Power Plant in Xiamen is significant. Two dimensional high spatial resolution temperature and acoustic tomography inversion of flow field in typical estuarine and coastal regions with complex flow field distribution are studied theoretically. The relationship between the number of acoustic stations, measurement errors and inversion accuracy is discussed, and the widely used Fourier series model is numerically studied in the case of high resolution and high order. The results show that the sound velocity, temperature distribution and flow field at a high spatial resolution of 40 m are accurately reconstructed by acoustic tomography theory. Furthermore, the 15kHz high frequency acoustic tomography observation equipment in estuarine and coastal areas has been developed. Based on NI data acquisition card and LabVIEW programming, the time synchronization of microsecond precision is realized by using the hardware of GPS, and the accurate measurement of propagation time is realized. Finally, a high frequency acoustic tomography observation experiment was carried out in the Lujiang Strait of Xiamen. The sound velocity and velocity variation of the Lujiang Strait were obtained by measuring the sound reciprocal propagation time. The measurement of the tidal current in the Lujiang Strait is accurate and consistent with the previous observation and model data. In the experiment, the length of modulation pseudorandom code, the SNR of received signal and the error of velocity measurement are compared. Theoretical and experimental studies show that high frequency acoustic tomography in estuarine and coastal areas provides a valuable acoustic method for high resolution temperature, velocity distribution and current measurement.
【学位授予单位】：厦门大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：P733.2

【参考文献】