全水深多波束测深系统Seabeam3012在西太平洋马里亚纳海山区地形测量中的应用

中国科学院海洋研究所在开展西太平洋马里亚纳海山区多学科综合科学考察的过程中,利用"科学"轮船载的全水深多波束测深系统Seabeam3012对多个海山进行了地形测量工作。针对作业过程中遇到的恶劣海况导致采集数据质量差、多波束系统易检测错误海底信息、测线布设难度大等问题,提出了基于船体姿态对数据质量影响分析的多波束测线方向优化、基于地形变化并参考浅地层剖面资料的作业参数优化和基于实时采集情况的多波束采集测线布设优化等一系列措施,有效地提高了海山区多波束数据采集质量,并提高了作业效率。获得的高品质地形数据,为多学科协同研究奠定了基础,为ROV等设备的现场作业提供了安全保障。     

A new bathymetric model for the central Fram Strait

Based on data from R/V Polarstern multibeam sonar surveys between 1984 and 1997 high resolution bathymetry has been generated for the central Fram Strait. The area insonified covers approx. 36,500 km² between 78–80°N and 0–7.5°E allowing the creation of a Digital Terrain Model (DTM) with 100 m grid spacing. The DTM was utilized for contouring and generation of a new series of bathymetric charts (AWI Bathymetric Charts of the Fram Strait, AWI BCFS) at a scale of 1:100,000. The paper starts with a brief introduction to the regional setting of the study area comprising information on the local links between bathymetry, sea ice transport and water mass exchange. The bathymetric feature names used in this article and how they were chosen is outlined. Next, the input data and processing applied are described. Thereafter the newly created grid and contour data are put into context with existing data sets. Finally the main bathymetric features of the area are characterized and the generated data products available for public disposal are specified.     

基于EGM模型的多波束无验潮测深技术应用

多波束水深测量中受潮汐因素的影响,测量垂直基准是变化的,具有瞬时性。传统多波束测量,需在测区内设立一个或多个验潮站进行同步水位观测,最终将水深归算到深度基准面上。针对多波束水深测量中垂直基准转换的复杂性问题,文中基于地球重力场模型,结合测区内实测的GNSS/水准数据,通过插值算法建立了测区范围内似大地水准面精化模型,构建了多波束无验潮水深测量的垂直基准转换模型。通过实例表明,该方法有效地消除了潮汐、动态吃水及涌浪等因素影响,直接获取深度基准面的水深值,提高工作效率,可满足近岸多波束水深测量的工作需求。     

Seafloor acoustic remote sensing with multibeam echo-sounders and bathymetric sidescan sonar systems

This paper examines the potential for remote classification of seafloor terrains using a combination of quantitative acoustic backscatter measurements and high resolution bathymetry derived from two classes of sonar systems currently used by the marine research community: multibeam echo-sounders and bathymetric sidescans sonar systems. The high-resolution bathymetry is important, not only to determine the topography of the area surveyed, but to provide accurate bottom slope corrections needed to convert the arrival angles of the seafloor echoes received by the sonars into true angles of incidence. An angular dependence of seafloor acoustic backscatter can then be derived for each region surveyed, making it possible to construct maps of acoustic backscattering strength in geographic coordinates over the areas of interest. Such maps, when combined with the high-resolution bathymetric maps normally compiled from the data output by the above sonar systems, could be very effective tools to quantify bottom types on a regional basis, and to develop automatic seafloor classification routines.     

Computer simulation of multibeam echo sounding over rough seafloor

A computer code that simulates multibeam echo‐sounding over realistic (three‐dimensional) bathymetry was used to compare available sounding systems. Two‐dimensional modeling dealt with the resolution of seafloor bathymetry and with the effect of postprocessing algorithms for some typical multibeam systems. The 2‐D bathymetric inputs were idealized bottom features. Three‐dimensional modeling dealt with the gross character of the seafloor, as detected by echo‐sounding systems. The 3‐D bathymetric inputs were realizations of terrain generated by a stochastic model of seafloor roughness. Three‐dimensional modeling indicated that the sounding system may slightly shift the location of peaks within the beam footprint. In addition, the simulated measurements were more sensitive to low‐wavenumber features (i.e., large‐scale roughness) than to high‐wavenumber features (i.e., small‐scale roughness). Resolution gradually decreased with increasing distance from centerline, due to the increasing footprint size of beams at increasing angular distance from the vertical. Lineated terrain was also smoothed by simulated echo‐sounding; lineations may indeed remain undetected if sounding system parameters are not properly selected. Inversion of the simulated measurements indicated that echo‐sounding measurements are dependent not only on the characteristics of the sounding system itself, but on other factors such as the character of the roughness and the orientation of the survey relative to the strike of lineations. The modeling technique provides a way to quantify the system response of a multibeam echo‐sounding system. This work resulted in recommendations as to the most appropriate system for an application in an area of rough bathymetry, and it led to the establishment of criteria for comparing multibeam systems in future applications.     

Processing and analysis of Simrad multibeam sonar data

The common approach to analysing data collected with multibeam and sidescan sonars is to visually interpret charts of contoured bathymetry and mosaics of seabed images. However, some of the information content is lost by processing the data into charts because this involves some averaging; the analysis might uncover more information if done on the data at an earlier stage in the processing. Motivated by this potential, I have created a software system which can be used to analyse data collected with Simrad EM1000 (shallow water) and EM12 (deep water) multibeam sonars, as well as to generate bathymetry contour charts and backscatter mosaics. The system includes data preprocessing, such as navigation filtering, depth filtering (removal of outlying values), and amplitude mapping using the multibeam bathymetry to correctly position image pixels across the swath. The data attributes that can be analysed include the orientation and slope of the seafloor, and the mean signal strength for each sounding. To determine bathymetry attributes such as slope, the soundings across a number of beams and across a series of pings are grouped and a least-squares plane fitted to them. Bathymetric curvature is obtained by detrending the grouped data using the least-squares plane and fitting a paraboloid to the residuals. The magnitudes and signs of the paraboloid's coefficients reveal depressions and hills and their orientations. Furthermore, the seafloor geology can be classified using a simple combination of these attributes. For example, flat-lying sediments can be classified where the backscatter, slope and curvature fall below specified values.     

基于CUBE算法的多波束测深数据自动处理研究

对CUBE算法自动处理多波束测深数据的模型建立、格网节点的多重估计和最优估值选取准则进行了详细介绍,深入分析了多重估计的实用性,并通过实测数据对该算法进行实现.利用了抗差Kalman滤波改进CUBE算法.通过模拟数据对改进的CUBE算法进行实验,验证了算法改进的必要性.     

利用MB-System软件进行多波束测深数据处理的研究

MB-System软件包是一套运行于L inux系统下的针对多波束测深数据处理的软件工具,它可以对原始数据和波束数据进行灵活编辑,并利用强大的绘图功能对结果进行显示。利用MB-System软件包对国外典型的多波束测深数据进行了处理与结果显示,结果体现了此软件相较于其他同类软件兼容性强、应用灵活的特点;然后,文中对国产首台便携式多波束测深仪湖试数据进行了格式转换,并对转换后的数据使用MB-System进行处理,结果验证了数据的有效性与正确性。     

在疏浚工程检测中的多波束数据后处理方法研究

在对多波束测深系统实际测量数据进行数据后处理时,由于采用不同的网格化处理方法,可能会使测量结果产生较大差异。通过对不同的网格化处理方法测量结果的影响分析,介绍了一种全新的网格化处理思路,在疏浚工程检测中,面对大量、密集的多波束测深数据,能更好地满足检测目的,使其能有效的指导疏浚工程施工或为工程竣工验收提供有力依据。     

基于单景高分辨率光学卫星遥感影像的浅海水下地形提取

本文基于海浪波折射现象和浅水波理论,提出了一种基于单景高分辨率光学遥感影像的浅海地形提取方法。首先,基于浅水波理论推导出适用于浅海区域的水深与海浪波长、频率的定量关系,针对近岸光学遥感图像复杂的海浪特征,讨论了两种海浪波长提取方法,即FFT方法和剖面线法。然后提出了基于长距离波长波动分析的海浪频率计算方法,解决了单景遥感影像的波浪频率计算难题。最后,利用单景QuickBird高分辨率光学遥感影像,以海南岛三亚湾为研究区域进行了应用实验,结果表明,对12m以浅的浅海区域,在不需要任何辅助参数的情况下,反演获得了浅海地形(DEM),经与1:25000比例尺海图的水深对比验证,地形趋势吻合良好,反演水深的均方根误差为1.07m,相对水深误差为16.2%,表明该方法适合于浅海水下地形的提取,且具有无需实测水深数据和环境参数的支持的优点。     

适用于U型阵多波束系统的高分辨底检测算法

在多波束回声声纳系统中,高分辨处理算法例如MUSIC、ESPRIT,被广泛应用于海底地形的测绘。在应用高分辨算法时,一条均匀线阵是必要条件。然而,由于系统覆盖范围/分辨率的需求以及安装空间的限制,在多波束系统中经常会采用特殊形状的接收阵列,这使得高分辨算法无法直接应用。同时回波信号的短时平稳特性使得难以估计出协方差矩阵,这也增加了高分辨算法在多波束系统中的应用难度。本文首先介绍一种基于多角度子阵波束形成的ESPRIT算法,该算法能降低高分辨算法对信噪比、样本点数和计算能力的要求。仿真表明此算法能提供更好的分辨力。接着提出一种将基于多角度子阵波束形成的ESPRIT算法与虚拟阵列变换相结合的高分辨底检测算法,并针对高分辨底检测算法在U型阵上的应用进行了探讨。计算机仿真和试验数据处理结果验证了文章所提高分辨底检测算法的有效性。     

冷泉羽状流多波束水体声学探测技术与应用

海底冷泉作为地球水圈与下伏岩石圈之间物质和能量交换的重要场所,其广泛发育于主动大陆和被动大陆边缘、深海扩张中心、汇聚板块边界、弧前盆地、断层以及泥火山发育区等区域。研究海底冷泉对于海洋工程安全、天然气水合物开发、海洋油气勘探、全球气候变化、碳循环和极端生物群落等方面具有重要意义。本文在系统总结海底冷泉探测技术方法的基础上,重点阐述了多波束水体声学探测技术及海底冷泉羽状流特征反演方法,对海底冷泉系统探测技术方法完善和应用具有重要意义。     

多波束声呐图像条带中央和边缘残差处理方法

多波束声呐图像是进行海底底质分类的主要数据源之一,由于受海洋噪声、声波散射和混响、仪器设备等因素影响,其经各项常规改正后仍存在明显残差,突出表现在中央波束区和条带重叠区,难以形成高质量的声呐图像。文中分析了多波束声呐图像残差的成因及影响,提出了一种基于多条带最小二乘拟合的多波束声呐图像残差处理方法。首先,得到相邻声脉冲(ping)信号中央区域、重叠区域以及整体趋势的拟合函数;然后,通过拟合函数计算得到中央和重叠区域的残差改正系数;最后,通过改正系数进行残差改正。实验分析表明,该方法在保留原始细节的基础上,有效削弱了残差对声呐图像的影响,对多波束声呐图像处理具有参考和应用价值。     

两种多波束反向散射强度数据归一化方法的建立与分析

多波束反向散射强度数据应用广泛,但由于受到角度响应的影响,导致生成的多波束声呐图像质量偏低,且现有角度响应改正方法在复杂海底底质环境下适应性较差。为此本文对散射强度进行分析,给出了两种多波束反向散射强度数据归一化方法,分别为基于高斯拟合以及角度响应的散射强度改正方法,前者主要是基于散射强度的变化规律进行改正,而后者则是基于声波的散射机理进行改正。实验结果表明两种方法较传统改正方法精度均有约30%的提升,并且角度响应方法较高斯拟合方法改正精度更高,但计算效率有所下降。以上实验验证了两种方法的有效性,实现了散射强度数据的归一化,提升了多波束声呐图像的质量。     

高分辨率测深侧扫声纳

文中介绍了由中国科学院声学研究所和美国亚迪技术开发（上海）有限公司联合设计和制造的高分辨率测深侧扫声纳,它能够同时获得高分辨率的海底地形和地貌。该声纳由电子分机和分别安装在载体左右两侧的两条声纳阵组成,最大工作水深6000m。声纳阵由一条发射线阵和10条间距为λ／2的接收线阵组成,λ为声波波长,其中8条线阵接收声信号,两边的两条为哑元。声纳的多子阵海底自动检测-子空间拟合信号处理方法能克服水声信道多途和复杂海底的影响,正确检测到海底的直达回波。2003年11月和2004年7月,声纳在中国浙江千岛湖进行两次长时间的湖试,获得了高分辨率湖底等深线图和地貌图,正确检测出湖底边长为0．5m立方体目标的高度。     

多波束反向散射强度数据处理研究

在探讨多波束测深系统反向散射强度与海底底质类型的关系基础上,研究影响反向散射强度的各种因素,主要分析了海底地形起伏、中央波束区反射信号对反向散射强度的影响,并给出了消除这些影响的方法;将处理后的“纯”反向散射强度数据镶嵌生成海底声像图,为海底底质类型划分以及地貌解译提供了基础数据和辅助判读依据.     

GeoSwath相干多波束系统原始数据的解析

通过分析GeoAcoustics公司的GeoSwath相干多波束系统的二进制原始文件结构,使用VC 6.0设计出各传感器字段的数据结构,并编程实现相干多波束数据的提取和图形可视化。该技术方法对于GeoSwath系统多波束数据的提取和分析处理有参考意义。     

Trend analysis and its tectonic implications using digital bathymetric data

Abstract

Quantitative and objective trend analysis of bottom topography in order to detect the tectonic structures has become available by use of the processed Seabeam data. The following two procedures of trend analysis are introduced.

(1) Edge detection procedures in digital image processing are applicable to the analysis of topography for extraction of the lineament of tectonic structures and prediction of the existence of faults based on the digital bathymetric data.

(2) Automatic calculation of water flow using the topographic grid data is used for estimation of not only water flow pattern and volume but also the construction of the ridge or trough axis by calculating the accumulated water volume. This method was also applied to the Seabeam bathymetric data. This is quite useful for detection of offset structures and hidden faults.

These two methods are applied to the topographic data obtained in the North Fiji Basin, which is characterized by active spreading ridges. The regional tectonic structure of the North Fiji Basin was found to be expressed by the topographic trend of the central axis.