浅地层剖面仪垂直测量性能分析

针对海道测量中浅地层剖面仪垂直测量指标模糊问题,根据声纳方程,讨论了浅地层剖面仪探测水底沉积层厚度的预报方法。分析了浅剖仪垂直地层分辨率的影响因素,并给出了垂直地层探测误差的改正方法。其结论对浅地层剖面仪实际测量作业具有指导价值。     

浅地层剖面仪的测量模拟

为获取声传播环境数据,实验中开展了水文调查和浅地层剖面仪的观测.由于声传播实验发射信号频率与接收船上的浅地层剖面仪信号频率接近,因此声传播实验信号在浅地层剖面仪测量图中产生了斜条纹.利用实验中水听器测量的信号模拟浅地层剖面仪的测量,解释了浅地层剖面仪测量图像中斜条纹的形成,并通过控制声传播实验信号的发射周期和时间模拟条...     

基于希尔伯特变换的Chirp信号浅地层剖面数据分析及转换

浅地层剖面系统在海洋工程勘察、海洋矿产资源探测等方面发挥着重要的作用。美国EdgeTech公司生产的3200系列是一种应用较为广泛的Chirp信号浅地层剖面系统,该仪器原始记录的JSF格式数据与传统的SEGY地震数据格式存在很多不同的地方,具体体现在文件头和道头部分,特别是数据记录方式上它同时记录了包络信号和振幅信号两种类型的数据。因此,编写适用的C程序代码将JSF原始数据转换为包络信号和振幅信号两种类型的SEG-Y标准地震数据,并运用该程序读取并转换了南海北部某区域的实测浅剖数据,并分析了浅剖资料解释中采用包络信号数据的原因,为利用振幅信号数据反演海底反射系数等后续工作奠定了基础。     

浅地层剖面仪GeoChirp Ⅱ图像中风浪变形效应的校正方法初探

当海面风浪较大时,测量船的摇摆会引起浅地层剖面图像的畸变,因此有必要研究风浪对浅地层剖面图像的影响及图像中风浪效应的校正方法,其中的关键问题是区分风浪效应和真实的沙波等海底床面形态。本文利用浅地层剖面仪GeoChirpⅡ在长江口所获得的浅剖图像对校正方法进行了研究。在所研究的实例中,海底周期性起伏的地形不是沙波,而是风浪效应引起的,用带阻滤波的方法可有效消除浅剖图像中的风浪效应,从而恢复真实的海底地形和地层形态。     

参量阵浅剖及电火花震源浅剖互补性分析

参量阵浅剖和电火花震源浅剖均具有分辨率高的特性,通过对比探测原理以及分析实测剖面,发现电火花震源浅剖和参量阵浅剖频带范围互不干扰,电火花震源浅剖的鬼波效应造成海底以下10m范围内地层判读困难,而参量阵浅剖则在10m以浅地层内具有极高的分辨率,基于二者良好的互补性,提出在海洋区域地质调查中同步应用参量阵浅剖和电火花震源浅剖两种技术手段的设想,进而提高区域地质调查精度,丰富区域地质调查成果。     

浅地层剖面仪在港池探测中的应用

介绍了3200XS型浅地层剖面仪工作原理及其数据处理过程,在港池开挖前进行浅地层剖面测量可以详细了解港池内各地层单元的分布和埋深,并对区内的灾害地质体或者障碍物进行有效识别,以保障施工安全和节约工程支出;结合海南某港池的浅剖探测实例,分析了该港池的地层单元划分及地层内物质识别,针对浅地层剖面测量前发射参数的选择和测量中的多次回波、调头区变形等问题等进行了探讨。     

浅地层剖面仪在大亚湾海底管道检测中的应用

浅地层剖面探测是海洋工程勘察的主要手段之一。阐述了浅地层剖面仪的工作原理，通过浅地层剖面仪在广州华德石化海底输油管道检测中的实际应用情况，分析浅地层剖面仪在工程区域内使用的优缺点，以期为今后该区域内工程勘察及管线检测工作起到一点参考作用。     

全海洋浅地层剖面仪及其应用

全海洋浅地层剖面仪(Topographic Parametric Sonar,TOPAS)PS 018系统是目前世界上最先进的浅地层剖面仪之一。该系统是全海洋宽带非线性差频浅地层剖面仪,可对海底地层进行全方位测量,同时还兼有测量水深的功能,最大地层穿透深度为150 m,最小分辨率为0.3 m。系统多种发射信号(Ricker波、Burst波和Chirp波)的选取方便了操作者使用,从理论上实现了全海洋测量功能。从实测剖面分析,该系统是中、深水地层测量的理想测量系统。     

浅地层剖面探测技术及应用

浅地层剖面技术是应用声学原理高效获取海底面之下浅部地质地球物理信息的探测技术,主要应用于海底浅地层信息探测和海底特殊目标调查等方面。以往研究者主要集中在浅地层剖面的具体应用,未对不同类型的浅剖应用效果进行综合对比分析,本文比较4种不同类型浅地层剖面系统的组成、工作方式和探测技术参数,认为不同尺度的探测目标需要应用不同类型的浅地层剖面系统。分析和对比不同震源类型浅剖的应用案例,发现电火花震源穿透能力最强,分辨率随工作频率的增大而提高;电磁式震源穿透深度与分辨率适中;压电换能器震源分辨率较高,穿透能力弱;参量阵震源利用差频原理,信号中包含高频与低频两部分,能够同时得到较高的分辨率与较大的穿透深度。未来浅地层剖面探测技术向深穿透、高分辨率、高效率、二维向三维甚至高维探测方面发展。     

脉冲压缩式浅地层剖面仪（PCSBP）

我所研制成功了具有当今国际先进水平的脉冲压缩式浅地层剖面仪（ＰＣＳＢＰ），又称Ｃｈｒｉｐ浅地层剖面仪。又称Ｃｈｉｒｐ浅地层剖面仪。它能同时提高地层穿透深度和地层分辨率，其定量化测量特性特别适合于定量研究海底介质的各种特性。本文介绍该仪器的工作原理、结构、性能、特点和使用结果。     

基于声学方法的南黄海浮游动物垂直迁移季节变化研究

为研究南黄海浮游动物垂直迁移的季节变化, 分析了2006 年至2007 年4 个季节布放潜标中声学测流仪的观测数据。结果是: 声学测流仪测量的后向散射强度呈现显著的日变化特征, 这是由浮游动物垂直迁移造成的; 在4 个季节中都出现这一凌晨向下、黄昏向上的垂直迁移, 但是垂直迁移发生的时间有季节变化。利用南黄海辐射通量的直接观测数据, 讨论了垂直迁移发生时间与光照的关系,结果表明垂直迁移的季节变化主要受光照的影响。这对于研究浮游动物垂直迁移机制有一定意义。     

Characterizing Observed Environmental Variability With HF Doppler Radar Surface Current Mappers and Acoustic Doppler Current Profilers: Environmental Variability in the Coastal Ocean

A network of high-frequency (HF) radars is deployed along the New Jersey coast providing synoptic current maps across the entire shelf. These data serve a variety of user groups from scientific research to Coast Guard search and rescue. In addition, model forecasts have been shown to improve with surface current assimilation. In all applications, there is a need for better definitions and assessment of the measurement uncertainty. During a summer coastal predictive skill experiment in 2001, an array of in situ current profilers was deployed near two HF radar sites, one long-range and one standard-range system. Comparison statistics were calculated between different vertical bins on the same current profiler, between different current profilers, and between the current profilers and the different HF radars. The velocity difference in the vertical and horizontal directions were then characterized using the observed root-mean-square (rms) differences. We further focused on two cases, one with relatively high vertical variability, and the second with relatively low vertical variability. Observed differences between the top bin of the current profiler and the HF radar were influenced by both system accuracy and the environment. Using the in situ current profilers, the environmental variability over scales based on the HF radar sampling was quantified. HF radar comparisons with the current profilers were on the same order as the observed environmental difference over the same scales, indicating that the environment has a significant influence on the observed differences. Velocity variability in the vertical and horizontal directions both contribute to these differences. When the potential effects of the vertical variability could be minimized, the remaining difference between the current profiler and the HF radar was similar to the measured horizontal velocity difference (~2.5 cm/s) and below the resolution of the raw radial data at the time of the deployment     

The Autonomous Ocean Profiler: a current-driven oceanographicsensor platform

The development and initial field test results of the Autonomous Ocean Profiler (AOP) are described. The profiler uses a hydrodynamic lift device to fly the instrument package up and down the water column along a taut vertical cable. Because the local currents drive the platform's vertical motion, power requirements are low, and therefore long, unattached deployments are possible. By using ARGOS or GOES satellite retrieval networks, the system can supply near-real-time data. The system provides profile data at very high vertical resolution in contrast to conventional buoys, which gather data only at fixed sensor depths. Because only a single set of sensors is required to cover the vertical range desired, the system is low cost and, for many applications, expendable. The initial deployment configuration is as an Arctic drifting buoy     

Development of acoustic suspended sediment monitor

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Motion compensation system for ocean profiling

The vertical profiles of ocean temperature and salinity measured with instruments lowered by cable from surface ships can be seriously affected by the nonuniform drop rate caused by ship motion. This paper describes a motion compensation system developed for conductivity, temperature, and depth profilers that significantly reduces the effect of ship motion on profiler drop rates, thereby enhancing the measurement capabilities of vertical profilers.     

Acoustic correlation current profiler

An acoustic correlation current profiler (ACCP) system is being developed to obtain vertical profiles of current velocities to ranges of approximately 1500 m. A single transmitter and a spatial array of eight receivers arranged in a novel geometry are employed to measure water mass displacement from receiver array cross-correlation functions. Test data from a shallow water ACCP operating at 76.8 kHz are presented and compared to model predictions as well as to velocity profiles obtained simultaneously during the tests from an adjacent acoustic Doppler current profiler. Additionally, predicted performance data for a lower frequency deep-water unit are presented     

南海北部中深层细结构混合研究

基于2007年8月获得的ADCP（声学多普勒流速剖面仪）海流资料和CTD（温盐深剖面仪）水文资料，应用Gregg模型对南海中深层内波尺度的混合进行估计，同时应用Thorpe尺度对中深层存在的垂向翻转及由此引起的混合进一步分析。两种方法均显示，吕宋海峡附近上层400m的耗散率及混合率均强于18°N断面，中深层两个区域的混合率并没有显著区别。这表明吕宋海峡上层400m，可能存在更活跃的内波活动，从而产生更强的内波混合和垂向水团翻转。Gregg模型估计的耗散率和混合率量级分别为10^-9W·kg^-1和10^-6m^2·s^-1。大部分CTD站位在中深层均存在垂向翻转，而且保持较高的发生率，翻转所对应的混合率并不随深度增加而减小。以上南海北部的细结构混合特征增强对南海中深层混合的认识。     

Vertical structure of the M<Subscript>2</Subscript> tidal current in the Yellow Sea

The vertical structure of the M₂ tidal current in the Yellow Sea is analyzed from data acquired using an acoustic Doppler current profiler. The observed vertical profiles of the M₂ tidal current are decomposed into two rotating components of counter-clockwise and clockwise, and restructured using a simple one-point model with a constant vertical eddy viscosity. The analyzed results show that the internal fictional effect dominates the vertical structure of the tidal current in the bottom boundary layer. In the Yellow Sea, the effect of the bottom friction reduces the current speed by about 20–40% and induces the bottom phase advance by about 15–50 minutes. In the shallower coastal regions, the effects of bottom topography are more prominent on the vertical structure of tidal currents. The vertical profile of the tidal current in summer, when the water column is strongly stratified, is disturbed near the pycnocline layer. The stratification significantly influences the vertical shear and distinct seasonal variation of the tidal current.     

Vertical structure of currents in the upper part of the continental slope of the Black Sea in the Region of Gelendzhik

The results of a joint analysis of the synchronous-profile ensemble of density and current velocity measured using the autonomous moored Aqualog profiler at the Gelendzhik experimental site of the Shirshov Institute of Oceanology in 2013–2015 are presented. The distribution of probability density of current velocity by directions reveals the presence of two well-pronounced maxima in the southeastern and northwestern sectors at all depths of measurements, which confirms the bimodal direction of the currents in the study site. We consider in detail the vertical structure of the density stratification and the current velocity corresponding to the modes determined from the maximum of the probability density distribution of the current velocity by directions. The averaged profiles of the kinetic, potential, and total energies are given. The results of isopycnic averaging over the entire ensemble of profiles indicate that possible self-similarity exists in the dependence of the vertical distribution of density and kinetic energy.     

Observations of turbulence under weakly and highly stratified conditions in the Ariake Sea

Observations of turbulence, stratification, and mean current were made using a microstructure profiler and an acoustic Doppler current profiler (ADCP) during four cruises at a central location in the Ariake Sea, under weakly and strongly stratified conditions. Continuous measurements of the dissipation rate of turbulent kinetic energy (TKE), ε, were made. These revealed that frictional bed turbulence with quarterdiurnal variation in the bottom boundary layer (BBL) was one of the most energetic sources of vertical mixing in the sea. Thickness of the BBL was strongly confined by the stable stratification. We investigate a relationship between the BBL height h and the Ozmidov scale. We present a systematic argument that describes the vertical structure and characteristic scales of velocity and turbulence inside the frictional BBL, where the stratification persisted. Considerable deviation of observed vertical shear from the law of the wall indicated a modification of turbulent scales by the stratification. Shear stress calculated from the velocity data using vertical integration of the equation of motion was found to decrease approximately linearly with height. The TKE production rate P, estimated using the shear stress, was highly correlated with the dissipation rate. The buoyancy contribution to TKE balance in the BBL was quantified in terms of the flux Richardson number R _f as R _f?=?0.12.