时差法水位改正的精度评估方法研究

为实现对时差法水位改正结果的精度评估,根据协方差传播律,推导了时差法水位改正的误差方程,讨论了评估潮时差确定精度的方法,并通过数据试验对结果进行了验证。试验结果表明,最小二乘拟合法比相关系数法更能满足时差法水位改正精度评估对潮时差的要求;根据《海道测量规范》要求,试验海域潮时差中误差的限差为6.2min,验潮站网潮时差闭合差中误差的限差为1.0min;水位改正方差反映出了水位改正结果的合理性,可用以评估水位改正精度。     

时差对海洋磁力测量地磁日变改正的影响分析

为研究时差对磁测的影响,基于站间同步地磁日变曲线的特征,尝试采用同步比对法和相关分析法计算两站的时差.结论表明:同步比对法和相关分析法能反映站间真实的时差,当测区范围较小时(至少是在本文实例的两个地磁日变站之间),时差对地磁日变改正的影响很小,海洋磁力测量地磁日变改正时可以忽略其影响.     

海洋磁力测量地磁日变改正中的时差计算方法

为了消除或减小地磁日变化对海洋磁力测量的影响,提出采用同步比对法和相关分析法计算两日变站间地磁日变化的时差。分析表明:同步比对法和相关分析法得到的时差更能真实反映两站间的时间变化,建议在海洋磁力测量多站地磁日变改正时差计算中采用。     

热带气旋下海浪对大气向海洋输入的动量和能量的影响

海浪不仅决定着海洋表面的粗糙度,由热带气旋引起的海浪,还通过其发展演化控制着大部分的海气之间的动量和能量传递。本文采用热带气旋观测数据IBTrACS和海浪模式WW III的模拟结果探究了热带气旋下海浪对大气向海洋输入的动量和能量的影响。结果发现,近30 a热带气旋的强度约每10 a增加 1 m/s,但移速没有明显变化。热带气旋的强度越大,从大气输入到海浪和从海浪输入到海流中的动量之差和能量之差也越大。由于热带气旋的风场和海浪场都有较强的不对称性,海气动量差和能量差也表现出非均匀分布:动量差较大的区域在热带气旋移动方向的后方,能量差的最大值则分布在右后象限,且二者均为左前方比较小。逆波龄与动量差和能量差呈高度正相关,相关系数约为0.95,说明波越年轻吸收的动量和能量越多。气旋移速越快逆波龄越大,且热带气旋移动速度与动量差和能量差呈正相关,相关系数在0.8以上。因此,海浪影响着大气向海洋输入的动量和能量的分布和大小,在以后关于海洋边界动力学和热力学的研究中,考虑海浪的演化可能会使结果更加准确。     

Differentiation of coral trout (Plectropomus leopardus) based on an analysis of morphology and complete mitochondrial DNA: Are cryptic species present?

Two morphotypes of Plectropomus leopardus have been identified; morphometric and meristic analyses show that there is no diagnostic difference between them. A difference in color pattern was the most appropriate phenotypic character with which to distinguish between the two morphotypes. Complete mitochondrial DNA sequencing, however, indicated a clear difference between the two morphotypes. Barcoding analysis revealed no significant difference (P>0.05) in CO1 or ND2 divergence among intramorphotypic individuals, even between geographically separated populations, whereas the intermorphotypic CO1 and ND2 divergences were large enough (averaging 0.95% for CO1 and 1.37% for ND2) to clearly discriminate between the two morphotypes. The color pattern difference, geographical distribution, together with the mtDNA and barcode sequencing data, suggest that the two morphotypes should be of two subspecies or even two species.     

沿海水域火／核电厂冷却水水工布置的优化原则和实践

本文结合我国沿海水域电厂冷却水工程的工程特点,着重阐明了差位式工程布置原则,从理论上分析了差位式工程布置原则与常用的布置方法的区别,该工程布置原则在台山电厂的工程实例中得到了验证。     

Track Parameter Estimation from Multipath Delay Information

It is desired to track the location of an underwater acoustic source with range difference measurements from a stationary passive array. Many times, the array has only one or two sensors, and the multipath and intersensor range difference measurements are insufficient to localize and track a source moving along an arbitrary path [1]. Here, we propose to track sources with one- or two-sensur stationary passive arrays by making the simplifying assumption that the source's path can be described by a small set of so-called track parameters. Range difference information can then be used to estimate the track parameter set rather than the source location as a function of time. In this paper, we choose the track parameters to specify a straight-line constant-velocity constant-depth path. Cramer-Rao bounds are presented for estimating these track parameters from the time history of multipath and intersensor range difference measurements. It is shown that this track parameter set cannot be accurately estimated from the time history of a single multipath range difference without side information (an independent velocity estimate, for instance), although multipath and intersensor range difference measurements from a two-sensor array are generally sufficient to estimate the track parameter set. Computationally efficient techniques are presented which estimate track parameters from range difference measurements taken from one- and two-sensor arrays. Monte-Carlo simulations are presented which show that these techniques have sample mean-square error approximately equal to the Cramer-Rao bound when a single multipath range difference and an independent velocity estimate are available. The sample mean-square error is shown to be in the range of two to ten times the corresponding Cramer-Rao bounds when these techniques are applied to two-sensor range difference data.     

一种基于偏度平衡的LiDAR点云滤波方法

在地形起伏区域,针对免阈值的偏度平衡滤波方法存在利用高程难以满足算法假设条件、利用强度信息面临异物同强度等问题,提出基于高差的偏度平衡方法。该方法是在点云与初始地面TIN间高差计算的基础上,采用偏度平衡方法进行LiDAR点云滤波。利用ISPRS提供的测试数据对该方法进行实验,结果表明:在地形起伏区域,点云高差能够满足偏度平衡方法的假设条件,并且基于高差的偏度平衡方法滤波有效。     

Why does the Sea Level Difference between Kushimoto and Uragami Show Periods of Large Meander and Non-Large Meander Paths of the Kuroshio South of Japan?

The sea level difference between Kushimoto and Uragami, located to the west and east of the southern tip of the Kii Peninsula, is relatively large in periods of non-large meander path (nLMP) of the Kuroshio south of Japan in comparison with periods of large meander path (LMP). Based on this clear relationship, the sea level difference between Kushimoto and Uragami has been used as an index showing the periods of nLMP and those of LMP of the Kuroshio south of Japan. It has been pointed out that warm and saline Kuroshio water, separated from the main path of the Kuroshio, has a tendency to approach the western area off Kii Peninsula to off Muroto Peninsula in periods of nLMP, while it approaches the eastern area off Kii Peninsula to Omae-zaki in periods of LMP. On the basis of this observational evidences, the dynamic background underlaying the well-known relationship between the Kuroshio path and the sea level difference between Kushimoto and Uragami is examined in the present study, using the temperature and salinity data observed by Wakayama Prefectural Fisheries Experimental Station and Fisheries Research Institute of Mie. It is shown that deviations in vertically integrated specific volume off Kushimoto and Uragami almost equal deviations in observed sea level at Kushimoto and Uragami, respectively. It is also shown that the difference in vertically integrated specific volume between off Kushimoto and off Uragami almost equals the difference in observed sea level between Kushimoto and Uragami. As for the Kuroshio water, the high-temperature contribution is predominant for its specific volume rather than that of high salinity, which yields thermal expansion in comparison with coastal water. Because the difference in vertically integrated specific volume between off Kushimoto and off Uragami almost equals the difference in observed sea level between Kushimoto and Uragami, it is concluded that the relationship between the Kuroshio path and sea level difference between Kushimoto and Uragami is caused by the different approaching of the warm Kuroshio water between in nLMP periods and in LMP periods.     

采用改进的盐度场数值格式模拟珠江口盐度分层现象

采用基于Backhaus的三维斜压模式计算珠江口水动力特性，重点模拟了夏季丰水期盐度分层现象；改进了原模式的盐度差分格式和方程，采用二阶精度差分格式并引入了物理扩散项。结果表明，改进后的盐度差分方程能较好地反映珠江口盐度成层现象。     

Seasonal variability of the barotropic and baroclinic motion in the Tsushima-Korea Strait

The aim of this study is to elucidate the seasonal variation in the volume transport through the Tsushima-Korea Strait using the sea level difference across the Strait. The sea level difference associated with the baroclinic motion is estimated from the geostrophic current profile, which is calculated as its vertical integrated transport is zero, using the CTD data from 1988 to 1990. The sea level difference associated with the barotropic motion is estimated by subtracting the sea level difference associated with the baroclinic motion from the observed one. The range (maximum-minimum) of the seasonal variation in the volume transport is evaluated about 0.7 Sv on the average, using the sea level difference associated with the barotropic motion. It is one third of the seasonal variation in the volume transport which is estimated from observed sea level difference on the assumption that no baroclinic component exists. Such analyses also indicate that the volume transport was at a maximum in early winter and at a minimum in early spring from 1988 to 1990. The negative correlation is also found between the volume transport through the eastern channel and that through the western channel. Moreover, it is noticed that the seasonal variation in the surface current velocity in the Strait largely contains baroclinic motions which are locally caused in the Tsushima-Korea Strait.     

Gravity Anomaly and Tectonics in the Northern Part of the North Fiji Basin - Preliminary Result of the 1994 NOFI Cruise under the NEW STARMER Programme

A surface ship gravity survey was carried out in the northern part of the North Fiji Basin during the NOFI cruise by the R/V l'Atalante in August-September, 1994. The two ridges inside the study area, the South Pandora Ridge and the Tripartite Ridge, present different structures and states of isostatic equilibrium in terms of gravity anomaly and its tectonic implications. The former is supported by a restoring force of an imaginary elastic plate in the crust and the latter by the Airy type isostasy. These characteristics can be derived from the difference in magmatic activity, as influenced by the difference in lithospheric structure. The latter is characterised by greater active magmatism and hydrothermalism underneath the ridge than the former. Such a difference in the magmatic activity and the horizontal scale of the shallow subsurface structure is derived from the difference in the stiffness or viscosity of the lithosphere beneath the two ridges.     

微孔管增氧和气石增氧对凡纳滨对虾室内养殖影响的比较研究

在凡纳滨对虾室内养殖池底部分别铺设微孔管和安装气石,在供氧功率相同的情况下比较微孔管增氧与气石增氧对凡纳滨对虾室内养殖产生的影响.研究表明:在养殖中后期微孔管增氧组的水温低于气石增氧组;从养殖60 d左右到养殖结束微孔管增氧效果明显优于气石增氧;亚硝酸氮、氨氮、非离子氨氮、无机磷与COD含量在2种增氧条件下没有显著性差异(P＞0.05);凡纳滨对虾体重变化、最终产量与成活率在2种增氧条件下没有显著性差异(P＞0.05);凡纳滨对虾血清溶菌酶活力、过氧化物酶相对活力、抗菌酶活力在微孔管增氧条件下较高并达到了显著性差异(P＜0.05);超氧化物歧化酶活力则在气石增氧条件下较高且达到显著性差异(P＜0.05);酚氧化酶活力在2种增氧条件下不存在显著性差异(P＞0.05).     

海洋磁力数据地磁日变时差校正的局部极值比对法

为了对海洋磁力数据进行更精确合理的地磁日变校正,参考多台站地磁观测数据时差计算的方法,总结出一种适合于海洋磁力数据地磁日变时差校正的方法——局部极值比对法。利用局部极值比对法对南海北部两条海洋磁力测线进行地磁日变时差校正后,海洋磁力数据与陆地地磁日变数据的相关系数分别提高到0.98和0.92。通过与经度差法的比较,证明局部极值比对法可以提高地磁日变时差计算的精确度和海洋磁力数据处理的效率。该方法为今后的海洋磁力调查工作提供了一种精确有效的工具。     

高频雷达OSMAR流速探测精度的对比验证

高频雷达探测海洋表面流与常规海流计测量海流是两种不同的测量方式。本文根据 2种观测方法所获取资料的不同特点 ,对引起 2种测量方法流速测量差异的主要误差进行了分析 ,并采用合适的方法对这些主要误差进行了量化估计。研究发现 ,2种测量方法取样的空间差异、时间差异以及仪器的观测误差等是构成高频雷达与常规海流计测量结果差异的主要因素。充分考虑这些因素对流速测量的影响能较大的提高高频雷达流速对比验证的精度     

海道测量声剖密度的确定方法研究

基于声剖选取引起的深度误差模型,利用实测数据,分析比较了不同选取方法对测深结果的影响。通过仿真计算,对相邻时刻声剖点的平均声速差值与深度、波束角、断层差值的关系进行了阐述,提出了通过确定相邻声剖点平均声速差值来确定声剖密度的方法,对实际工作有一定的参考价值。     

Measurement of Ocean Surface Currents by the CRL HF Ocean Surface Radar of FMCW Type. Part 2. Current Vector

The Communications Research Laboratory (CRL) has been developing high-frequency ocean surface radars (HFOSRs). The CRL dual-site HFOSR system can clarify the distribution of surface currents with a nominal range of 50 km. This paper presents a theoretical and experimental analysis of the measurement error of the current vector obtained by the CRL HFOSR system, using a comparison of instantaneous current vectors acquired by the HFOSR system and current meters moored at a depth of 2 m, taking account of the vertical current shear. The theoretical analysis shows that the probability distribution of the measurement error of the current vector forms concentric ellipses at a spatial scale that depends on the RMS measurement error of radial current velocity and with an aspect ratio that depends only on the azimuthal difference of the radar beams. When the azimuthal difference is a right angle, the measurement error of the current vector is at a minimum. A comparison between instantaneous current vectors measured by the CRL HFOSR system and moored current meters shows that the distribution of the difference vector between the radar current and the meter current agrees well with the theoretical measurement error of the current vector and that the RMS of difference vector length is about 10 cm s^–1 while the azimuthal difference between two radar beams is between 45 and 135 degrees. The accuracy of current measurement by the dual-site HFOSR system is therefore considered to be less than 10 cm s^–1 in this range of azimuthal difference. The theoretical analysis will be applicable for a wider range of the azimuthal difference of the radar beams.     

地磁日变数据时间同步相关系数分析

通过对两站地磁日变数据的分析,提出了利用相关系数法解算地磁日变观测站间测量时差的方法,导出了地磁日变观测站间观测数据的相关系数计算公式.并通过实例分析,验证了地磁日变数据利用相关系数法进行时间同步分析的正确性.在进行实例分析时注意到,短距离站间时差与一直使用的经度差时差法得到的时差出入很大,通过对相关系数时差法正确性的进一步验证后,对传统经度差时差改正方法的合理性提出质疑.     

沿海验潮站GNSS观测网BDS与GPS基线处理精度分析

为了评估北斗卫星导航系统（BDS）用于验潮站沉降监测的可靠性和精度,该文利用北海区沿海8个验潮站2022年全年的GPS和BDS观测数据,从基线解标准均方根误差、基线重复性和GPS与BDS基线互差等方面对GPS和BDS解算结果进行对比分析。结果表明,BDS基线解的NRMS值在0.17～0.25之间,GPS基线解的NRMS值在0.18～0.23之间,二者基线解的NRMS值基本相当;GPS基线解的长度和各分量基线重复率平均值要小于BDS,从GNSS网固定误差和比例误差看,GPS和BDS的基线长度重复性精度达到10-9～10-8量级,基线东西和南北分量重复性达到10-9量级,基线垂直分量重复性精度达到10-7～10-8量级。在GPS和BDS基线结果互差方面,GPS解算得到的基线长度均要大于BDS,二者平均差值为10.7 mm;东西分量差值最小,其次是南北分量,垂直分量差异最大,南北分量、东西分量和垂直分量差值平均值分别为-8.5 mm、-3.7 mm和10.6 mm。南北分量、东西分量、垂直分量和基线长度差值平均值最大值分别为23.6 mm、20.9 mm、30.4 mm和22.1 mm。总体...     

浙江近海潮汐潮流的数值模拟

用三维陆架海模式(HAMSOM)对浙江近海的潮汐、潮流进行了数值模拟,并采用网格嵌套和动边界技术对原模式作了改进,以提高计算的精度,改进后的模式在浙江近海的应用中被证明是成功的.沿岸50个潮位站计算与实测值的比较表明,加入动边界以后的小区域细网格计算较之粗网格以及未加动边界以前精度普遍提高,比较的均方差结果为:M₂分潮振幅差4.6cm,相角差7.14°;S₂分潮振幅差5.0cm,相角差5.4°;K₁分潮振幅差2.25cm,相角差5.76°;O₁分潮振幅差1.56cm,相角差5.5°,可见计算与实测符合良好.另外,选取了105个实测潮流点,比较了表层M₂和K₁分潮流调和常数分量Ucosξ,Usinξ,Vcosη,Vsinη的实测值与计算值的偏差,结果表明计算与实测的符合程度较好.在此基础上,给出了各主要分潮的潮位同潮图、潮流同潮图、潮汐性质、潮流性质、潮流椭圆和潮流的运动形式等,发现4个主要分潮M₂,S₂,K₁,O₁在本区内均未出现无潮点;M₂分潮流在29°18'N,122°46'E处有一个圆流点.此外还得到了一些有意义的结论,都与实测情况符合良好,从而对整个浙江沿海区域的潮汐潮流特性有了一个全面认识.