海洋内波对多波束测深的影响与改正

发布时间：2018-09-09 12:09

【摘要】：我国拥有辽阔的海域面积,纵贯南北的漫长海岸线以及丰富的海洋资源。现代海洋高新技术的发展,高科技海洋仪器设备的开发运用,虽为开发海洋资源提供了前提与保障,但目前我国对海洋资源的开发利用仍着重于沿海开发,且我国海洋科学创新能力和支撑能力不足,不利于开展大规模的海洋资源开发。多波束测深技术是目前进行水下地形地貌测量的主要技术手段,水体中声波传播速度的变化将会引起其传播方向的变化,导致声线弯曲,是影响多波束测深精度的重要误差来源。海洋内波是一种广泛存在于我国沿海,发生在海水内部稳定层结处的重力波,其振幅可达数米到数十米,常见波长为几十米至几十千米,频率介于浮性频率和惯性频率之间。海洋内波发生时,其携带的巨大能量会导致海水较高的流速,不仅会对海洋石油钻井平台和水下潜艇会造成严重威胁,且变化剧烈的等密度面会对经过的声线传播方向和声速大小发生改变。因此,研究分析海洋内波对多波束测深精度影响机理,探索误差改正方法,对于提高多波束测深精度和效率,反演海洋内波波长、传播方向等基本特征是迫切且必要的。本文用数值仿真的方法,模拟了在海洋内波经过测区时造成声速跃层发生垂直位移和倾斜情况,进而分析了内波对多波束声线传播路径的影响机理,并在此基础上,构建了测区的海底DEM,通过分析DEM特征与海底地形起伏规律,提出并验证了从海底DEM反演海洋内波的传播方向、波长和振幅等其近似值信息的方法,并跟据反演得到的海洋内波近似参数构建了内波函数,对声线重新进行三维声线跟踪,获取更精确的海底DEM以用于反演精确的海洋内波参数,通过如此若干次迭代计算,既反演了海洋内波参数也削弱了海洋内波对多波束测深的影响。
[Abstract]:China has a vast sea area, a long coastline and rich marine resources. The development of modern marine high and new technology and the development and application of high-tech marine instruments and equipments have provided a prerequisite and guarantee for the development of marine resources, but at present, the exploitation and utilization of marine resources in China is still focused on coastal development. And our country marine science innovation ability and the support ability is insufficient, unfavorable to carry on the large-scale marine resources development. Multi-beam bathymetry is the main technique for underwater topographic and geomorphologic survey. The change of acoustic wave velocity in water will cause the change of its propagation direction and lead to the sound line bending. It is an important error source that affects the precision of multi-beam sounding. Ocean internal wave is a kind of gravity wave which widely exists in the coastal area of our country and occurs in the stable layer of sea water. Its amplitude can reach several meters to tens meters, the common wavelength is tens to tens of kilometers, and the frequency is between floating frequency and inertial frequency. When the ocean internal wave occurs, the huge energy it carries will lead to the higher velocity of the sea water, which will not only pose a serious threat to offshore oil drilling platforms and underwater submarines. The direction of sound propagation and the magnitude of sound velocity will be changed when the isodensity surface changes sharply. Therefore, it is urgent and necessary to study and analyze the influence mechanism of ocean internal wave on the accuracy of multi-beam sounding, and to explore the error correction method for improving the accuracy and efficiency of multi-beam sounding, retrieving the wave length and propagation direction. In this paper, the vertical displacement and tilt of the acoustic cline caused by the ocean internal wave passing through the measured area are simulated by numerical simulation, and the influence mechanism of the internal wave on the propagation path of the multi-beam acoustic line is analyzed. By analyzing the characteristics of DEM and the regularity of seabed topography fluctuation, the method of retrieving the approximate information of ocean wave propagation direction, wavelength and amplitude from seabed DEM is proposed and verified. And the internal wave function is constructed with the approximate parameters of ocean internal wave obtained from inversion, and the sound line is tracked again in three dimensions to obtain more accurate seabed DEM for retrieving accurate ocean internal wave parameters, which are calculated through several iterations. The inversion of ocean internal wave parameters also weakens the influence of ocean internal wave on multi-beam sounding.
【学位授予单位】：山东科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P229

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