海洋水声调查及信号处理方法的研究

水声环境包括海洋中影响声信号传播的各种参数,传统上,这些参数的测量都是由从事水声及其设备研究的专业人员进行,而且需要许多实验室测量仪器,所以,一直被称为水声实验。就如何将海洋水声参数的测量工程化,实现多航次、大面积的高效率水声调查,对信号获取方法、信号分析与处理方法进行了探索性研究,并在专门的数据处理软件研制中,对提出的联合时频分析法进行了验证。     

海洋水声环境调查数据处理系统的设计与实现

针对目前海洋环境调查现状,结合国内现有的技术条件和现有的处理方法、原理,详细论述了海洋水声环境调查处理系统软件主要功能的设计及关键技术,该系统软件满足海洋调查的需求,极大提高了海洋环境数据处理的自动化、数字化和信息化程度。     

海洋声学调查数据处理系统的实现及关键技术

针对目前我国海洋水声环境调查需求,结合国内现有的技术条件和现有的处理方法、原理,详述了海洋声学调查数据处理系统的实现途径及关键技术的解决,该系统软件满足我国目前海洋调查的需求,提高了海洋环境数据处理的自动化、数字化和信息化程度。     

基于压缩传感的OFDM水声信道估计方法研究

简要介绍了两种经典的基于压缩传感(CS)的稀疏信号重构算法:匹配追踪(MP)和正交匹配追踪(OMP)。结合逆矩阵的阶数递归算法,针对OMP算法复杂度高提出了改进型的基于阶数递归的OMP算法,简称为ORMP算法。经研究发现,水声信道的冲击响应是典型的稀疏信号。因此,把基于压缩传感的ORMP算法应用到水声信道估计中,并通过仿真和海试实验验证了算法的可行性及优越性。     

Acoustic characteristics of the north-eastern Atlantic Ocean

The vertical structure of the climatic and seasonal fields of the estimated speed of sound in the north-east Atlantic Ocean is considered. Zonation according to typicalc(z) profiles allowing for seasonal variations was carried out. It is shown that the water areas with a dual-channel vertical hydroacoustic structure vary essentially throughout the year. The features of the structure of the sound speed field in the lenses of the Mediterranean Sea waters are investigated. The effect produced by a lens on the characteristics of the sound propagation is studied.Translated by Mikhail M. Trufanov.     

正交解调及复自相关频率估计在海流测量中的应用

正交解调技术在使用复自相关算法进行频率估计中具有非常重要的作用,简要介绍了正交解调技术和复自相关算法在声学多普勒海流计中的应用.     

单通道低功耗大容量海洋声信号测量仪的设计与实现

海洋环境噪声是海洋声场的背景场,通常被当作干扰项,许多国家纷纷投入力量,开展海洋环境噪声数据获取、分析及噪声场建模工作。针对海洋环境噪声的测量,同时为了满足设备在水下较长时间工作,设计了一种基于ARM芯片的海洋声信号高速数据采集系统,即单通道低功耗大容量海洋声信号测量仪,集成温度传感器、压力传感器和同步模块,具备定时和连续两种工作方式。采用ARM Cortex-M3微控制器LPC7168控制24位AD芯片ADS1271实现声信号采集,最高采样速率可达50 k,采集的AD数据以文件格式存储在SD卡(容量256 Gbyte)中。采用单片机PIC12F509作为值班电路,PIC12F509在控制系统工作时作为看门狗使用。经过实验室试验和湖试,验证系统工作稳定,数据采集存储正常,在消声水槽完成与DSG比测试验,通过对回放数据的分析,验证采集数据一致性较好。试验证明声信号测量仪是获取海洋环境噪声的重要设备。     

Model for the Processing and Estimation of Dual Frequency Echo Sounder Observations in Detailed Bathymetries

The dataset acquired by an echo sounder generally comprises outliers and erroneous measurements which must be automatically processed. The main aim of this research is the development and validation of an algorithm which permits detecting outliers, estimating their real value from data acquired with a multifrequency echo sounder, and verifying the measure according to the desired accuracy. The process considers the nature of the seabed and improves the density and number of lectures without globally compromising the precision, but enhancing it in areas with anomalous measurements. Twenty-nine percent of this type of measurements, which would have been otherwise rejected, have been estimated.     

海洋声层析研究的两个热点问题

综述了目前海洋声层析研究的两个热点问题 ,归纳了用声学方法监测气候变化和反演内波两个领域所取得的研究进展 ,总结了研究过程中存在的问题     

Precise Positioning of Ocean Bottom Seismometer by Using Acoustic Transponder and CTD

We have obtained precise estimates of the position of Ocean Bottom Seismometers (OBS) on the sea bottom. Such estimates are usually uncertain due to their free falling deployment. This uncertainty is small enough, or is correctable, with OBS spacing of more than 10 km usually employed in crustal studies. But, for example, if the spacing is only 200 m for OBS reflection studies, estimates of the position with an accuracy of the order of 10 m or more is required.The determination was carried out with the slant range data, ship position data and a 1D acoustic velocity structure calculated from Conductivity–Temperature–Depth (CTD) data, if they are available. The slant range data were obtained by an acoustic transponder system designed for the sinker releasing of the OBS or travel time data of direct water wave arrivals by airgun shooting. The ship position data was obtained by a single GPS or DGPS. The method of calculation was similar to those used for earthquake hypocenter determination.The results indicate that the accuracy of determined OBS positions is enough for present OBS experiments, which becomes order of 1 m by using the DGPS and of less than 10 m by using the single GPS, if we measure the distance from several positions at the sea surface by using a transponder system which is not designed for the precise ranging. The geometry of calling positions is most important to determine the OBS position, even if we use the data with larger error, such as the direct water wave arrival data. The 1D acoustic velocity structure should be required for the correct depth of the OBS. Although it is rare that we use a CTD, even an empirical velocity structure works well.     

海洋声层析的基本原理和应用

从射线声学和简正波声学的角度，概述了海洋声层析的基本理论，包括射线走时反演、简正波走时反演、简正波相位反演和简正波水平折射层析。海洋声层析以反演海水温度和流速为基础。还总结了声层析在海洋学研究中的应用。     

Estimation of Wind Wave Frequency Spectra by Use of the Arcsine Law

In the present study,the surface elevation of wind waves oberved in laboratory and in the Bohai Sea are adopted for the estimation of the wind wave frequency spectrum by use of the method of the arcsine law(MAL).The traditional method uses the surface elevation to calculate the correlation and then estimate the frequency spectrum while the MAL,presented by Yu and Lan(1979),uses the time sequence of zero-crossing points of surface elevation rather than directly the surface elevation to calculate the correlation.66 sets of wind wave data obtained in laboratory and 420 sets of data observed in the Bohai Sea are adopted for the examination of the method introduced by Yu and Lan.Results show that the MAL can give reliable estimation of wind wave spectra.Correlation and form of spectra estimated by the MAL are similar to those estimated by the traditional method.The peak frequency and the spectral density in peak frequency by the MAL are close to those obtained by the traditional method.     

State Estimation of the North Pacific Ocean by a Four-Dimensional Variational Data Assimilation Experiment

A four-dimensional variational data assimilation system has been applied to an experiment to describe the dynamic state of the North Pacific Ocean. A synthesis of available observational records and a sophisticated ocean general circulation model produces a dynamically consistent dataset, which, in contrast to the nudging approach, provides realistic features of the seasonally-varying ocean circulation with no artificial sources/sinks for temperature and salinity fields. This new dataset enables us to estimate heat and water mass transports in addition to the qualification of water mass formation and movement processes. A sensitivity experiment on our assimilation system reveals that the origin of the North Pacific Intermediate Water can be traced back to the Sea of Okhotsk and the Bering Sea in the subarctic region and to the subtropical Kuroshio region further south. These results demonstrate that our data assimilation system is a very powerful tool for the identification and characterization of ocean variabilities and for our understanding of the dynamic state of ocean circulation. This revised version was published online in July 2006 with corrections to the Cover Date.     

Estimation of insolation over the Pacific Ocean off the Sanriku coast

Surface solar radiation over the Pacific Ocean off the Sanriku coast has been estimated using Visible and Infrared Spin Scan Radiometer data supplied by the Geostationary Meteorological Satellite 5 for September, 1996 to June, 1997, when the Ocean Color and Temperature Scanner was functioning. The hourly and daily insolation is estimated with a spatial resolution of 0.01-degree grid. Thein situ surface short wave radiation obtained by the research vessel,Kofu-Maru belonging to the Japan Meteorological Agency is used for validation of the estimated insolation. It is shown that the estimated hourly and daily insolation has an rms (root mean square) error of 17.05% and 8.13%, respectively, which are the ratios between the rms error (W/m²) and the mean insolation (W/m²).     

Application of Linear Mean-Square Estimation in Ocean Engineering

The attempt to obtain long-term observed data around some sea areas we concern is usually very hard or even impossible in practical offshore and ocean engineering situations. In this paper, by means of linear mean-square estimation method, a new way to extend short-term data to long-term ones is developed. The long-term data about concerning sea areas can be constructed via a series of long-term data obtained from neighbor oceanographic stations, through relevance analysis of different data series. It is effective to cover the insufficiency of time series prediction method’s overdependence upon the length of data series, as well as the limitation of variable numbers adopted in multiple linear regression model. The storm surge data collected from three oceanographic stations located in Shandong Peninsula are taken as examples to analyze the number-selection effect of reference oceanographic stations (adjacent to the concerning sea area) and the correlation coefficients between sea sites which are selected for reference and for engineering projects construction respectively. By comparing the N-year return-period values which are calculated from observed raw data and processed data which are extended from finite data series by means of the linear mean-square estimation method, one can draw a conclusion that this method can give considerably good estimation in practical ocean engineering, in spite of different extreme value distributions about raw and processed data.     

River-like erosion within the Bounty Submarine Channel,Southwest Pacific Ocean

A multibeam bathymetric crossing of Bounty Channel, east of South Island New Zealand fortuitously imaged a large recent slump that partially dammed the channel. Together with a later, adjacent multibeam crossing, these bathymetric data show the average gradient for this section of the channel to be 15 m per km, steeper than the general average for the whole channel (∼3 m per km). In the immediate vicinity of the slump, there is a negative gradient followed downstream by a maximum gradient of 1450 m/km for a 70 m section of the channel. Typical riverine erosional features are seen in this section of the channel including an over-deepened basin at the bottom of the greatest slope as well as additional major slump features.     

频率编码水声遥控指令的抗多途对策

浅海信道中,多途干扰是水声遥控指令可靠检测的首要障碍,本文探讨频率编码遥控指令的抗多途对策,即通过阻塞多途来削落多途干扰。     

海洋综合测量声学系统间信号干扰的分析

针对海洋综合测量多种声学测量系统间的窄带相干声学干扰现象进行了理论分析，并针对克服窄带干扰提出了一些具有实用价值的建议。     

潮汐基准的量级分析与精度估算

海洋基准是大地测量基准在海洋及其他水域的扩展,是大地测量基准的重要组成部分,其中既包含大地测量类的基准,又有潮汐类的基准。潮汐类基准包括平均水位、深度基准和净高基准,它们都具有潮汐基准的特征,在不同国家、海区甚至不同时期的选择往往都不同,因此,这类基准存在着离散、跳变、不连续等诸多问题,且缺乏精度信息。海洋无缝垂直基准体系的建立与完善需要了解各种基准及其特点,本文在定义和数据来源的基础上对各类潮汐基准的量级进行分析并估算其精度。     

Acoustic imaging,visualization, and quantification of buoyant hydrothermal plumes in the Ocean

We develop and apply visualization and quantification methods to reconstruct hydrothermal plumes in 3D from acoustic images and to make the first direct measurements from the reconstructions of scalar properties that describe the behavior of two buoyant plumes discharging from adjacent black smoker chimneys. The actual behavior is then compared to that predicted by a classic simple buoyant plume model. The images are reconstructed as isointensity surfaces of backscatter from particulate matter suspended in the plumes. The measurements pertinent to the role of the plumes as agents of dispersal of heat and mass into the ocean include change with height of diameter, particle distribution, dilution, centerline attitude, surface protrusions, and connectivity. The protrusions are the surface expression of eddies and appear to follow a bifurcating helical flow pattern that resemble simulation of the naturally forced flow of coherent vortex rings as the eddies rise with the buoyant plume. These direct measurements and the derived entrainment coefficient are generally consistent with behavior predicted by the simple buoyant plume model and support engulfment by vortex shedding as a primary mechanism for entrainment of surrounding seawater. Deviations from predicted buoyant plume behavior are diagnostic of particle dynamics.