海洋潮位推算在水深测量中的应用

研究了用于海洋水深测量的天文潮加余潮水位订正方法，在沿岸测量中得到验证，数值精度符合测量标准要求。研究的主要内容包括：利用已有潮波的数值计算结果，分析网格点主要分潮的调和常数；利用相关的长期验潮站资料，分析所有分潮的调和常数，修正测量海域的数值计算结果，确定各网格点内的理论最低潮面；内插计算并扩展任意点主要分潮调和常数，推算该点的瞬时天文潮位，并利用长期验潮站观测数据推算任意点余水位，二者相加得出给定时刻的潮位。     

天津近海潮汐特征分析

对塘沽海洋环境监测站从1950年-2008年,59年的潮汐资料进行调和分析,分析了其分潮调和常数的变化曲线,并利用FFT谱分析方法对其调和常数的变化周期和原因进行了分析;之后应用FFT谱分析方法对去除天文潮后的余水位进行分解,分析了近50多年来年平均余水位的多层次周期分布,进而利用最小二乘法进行线性分析,分析了天津近海...     

天津近海潮汐特征分析

对塘沽海洋环境监测站从1950～2008年,59年的潮汐资料进行调和分析,分析了其分潮调和常数的变化曲线,并利用FFT谱分析方法对其调和常数的变化周期和原因进行了分析;之后应用FFT谱分析方法对去除天文潮后的余水位进行分解,分析了近50多年来年平均余水位的多层次周期分布,进而利用最小二乘法进行线性分析,分析了天津近海平...     

海道测量中几种水位改正方法的比较与分析

针对多波束测深易出现的因水位改正不完善导致的相邻测深条带间的拼接断层,分别采用天文潮预报、基于余水位配置的海洋潮汐推算以及基于日平均海面订正的海洋潮汐推算等方法进行水深测量水位改正。结果表明,后两种方法均适用于多波束水深测量水位改正。     

海道测量中几种水位改正方法的比较与分析

针对多波束测深易出现的因水位改正不完善导致的相邻测深条带间的拼接断层,分别采用天文潮预报、基于余水位配置的海洋潮汐推算以及基于日平均海面订正的海洋潮汐推算等方法进行水深测量水位改正。结果表明,后两种方法均适用于多波束水深测量水位改正。     

潮汐非调和常数的计算方法——Ⅰ.原理

潮汐非调和常数是一组用来描述港口潮汐特征的数据,应当从长期观测的高、低潮时间及高度中统计得出。然而在只有短期记录的情况下,由于潮汐存在着长周期的变化,直接统计得出的结果会出现相当大的误差。因此,在只有短期验潮的港口,人们常常利用潮汐的调和常数间接计算非调和常数;而调和常数则可利用短期记录求得,不会带来严重的误差。各国使用的潮汐非调和常数计算方法不尽相同。在我国,郑交振同志编著的《实用潮汐学》一书中全面地介绍了     

海道测量中跳变水位和缺失水位的补救方法

基于余水位的配置模型,通过潮汐调和分析,利用已知长期验潮站余水位结合临近短期验潮站天文潮位来恢复短期站的实际水位,并对其进行误差分析,证明基于余水位进行推算未知验潮站潮位的可行性与实用性。为了保证验潮仪采集数据的精确度,基于日(月)平均海面在较大的空间尺度内有较强的相关性这一原理,对短期验潮站验潮仪零点漂移进行检测,并对其进行误差分析。     

基于Grey-GMDH的模块化实时潮汐预报

为了提高潮汐水位的实时预测精度,本文提出了一种基于灰色的数据处理群模块化(Grey-GMDH)潮汐水位实时预测模型。模块化将潮汐分解为两部分:由天体引潮力形成的天文潮部分和由各种天气以及环境因素引起非天文潮部分。使用Grey-GMDH模型和调和分析模型分别对潮汐的非天文潮和天文潮部分进行仿真预测,然后将两部分的预测结果综合形成最终的潮汐预测值。并选用San Diego港口的实测潮汐值数据进行实时预报的仿真实验,实验结果验证了该方法的可行性与有效性并取得了良好的仿真结果,验证了模型有着较高的预报精度。     

海平面变化和调和常数不稳定性对一些工程设计参数的影响

对石臼所、连云港和坎门验潮站23 a(1975—1997年)水文观测资料进行了逐年调和分析。结果可以看出,不仅年平均海平面有逐年变化,而且分潮调和常数也存在明显的不稳定性。利用2种方法推算了3个站的23 a天文潮位,一是以某年(例如1975年)的年平均海平面和调和常数,另一是以当年的年平均海平面和调和常数推算3个站的23 a天文潮位。并据实测潮位和2种天文潮位推算值,计算出2种风增(减)水的年极值。由比较发现,3个站的2种年最高(低)天文潮位的最大差值达17~22 cm(-18~14 cm);石臼所和连云港的2种100年一遇风减水的差值均达20~30 cm,坎门的2种100年一遇风增水差值达10 cm。这些差值表明,在人们推算天文潮和计算风增(减)水时,不应该忽视年平均海平面变化和分潮调和常数的不稳定性。由逐年的调和常数计算了每年的海图深度基准面,其23 a的变化幅度在石臼所达11 cm,在连云港达21 cm。拟建沿岸工程点的年最高(最低)天文潮位变化的曲线,年极值风增(减)水变化曲线及海图深度基准面的年变化曲线可以利用工程点两侧长期验潮站的相应曲线经过工程点1 a观测资料推算出的相应值,内插求得。     

基于调和分析法与ANFIS系统的综合潮汐预报模型

港口沿岸地区以及河流入海口等地区的精确潮汐预报对于各种海洋工程作业有着非常重要的意义。潮汐水位的变化受到众多复杂因素的影响,而且这些复杂的因素往往有着较强的实变性和非线性。为了进一步提高沿岸港口码头等水域的潮汐水位的预测精度,本文提出了一种基于调和分析模型与自适应神经模糊推理系统相结合的模块化潮汐水位预测模型;并采用相关分析确定整个预测模型的输入维数;模块化将潮汐分解为两部分：由天体引潮力形成的天文潮部分和由各种天气以及环境因素引起非天文潮部分。其中调和分析法用于天文潮部分的预测,ANFIS用于预测具有较强非线性的非文潮部分。模块化综合了两种方法的优势,即调和分析法能够实现长期、稳定的天文潮预报,ANFIS能够以较高的精度实现潮汐非线性拟合与预测。模型使用ANFIS模型和调和分析模型分别对潮汐的非天文潮和天文潮部分进行仿真预测,然后将两部分的预测结果综合形成最终的潮汐预测值。此外,本文选用三种不同的模糊规则生成方法（grid partition （GP）,fuzzy c-means （FCM） and sub-clustering （SC））生成完整的ANFIS系统,并使用实测数据进行验证用以选取最优的ANFIS预测模型。最后将最优的ANFIS模型与调和分析模型相结合进行潮汐水位的最终预报。仿真实验选用Fort Pulaski潮汐观测站的实测潮汐值数据进行预报的仿真实验,仿真结果验证了该模型的可行性与有效性并取得了良好的效果,具有较高的预报精度。     

BPF法在海图基准面计算中的应用

为了船只航行安全，在海图上所标的水深一般并非指平均海面到海底的距离(平均水深)，而是从低于平均海面的某一个面到海底的距离，这个面叫做海图基准面。基准面的确定并无统一的方法，国际上只有一个原则的规定，即实际海面应当可能但很少可能低于它。这样规定既避免了在海图上给出过分浅的水深数值，又可保证航行的安全。 但世界海洋国家在实际确定基准面深度时方法很不统一，甚至有些并不甚符合上述原则。我国历史上曾采用过国外的许多种方法，十分混乱。五十年代以来曾采用弗拉基米尔斯基方法，但这种方法计算手续相当麻烦，效果有时也不够理想。这里我们将提出一种以 BPF 法为基础的计算海图基准面方法，并将由此得出的面叫做“近最低潮面”。此法计算较简便，用实测资料检验表明，所得结果较为合理。     

An alternative approach to the joint probability method for extreme high sea level computations

The joint surge-tide probability method for estimating the frequency of occurrence of extreme high sea levels is particularly useful when only a few years of sea level observations are available for the location of interest. The standard approach at present involves the convolution of the probability density functions of the tidal and surge elevations to obtain the distribution of total water level. An alternative approach is discussed here which is an adaptation of an existing, but different, method to render it suitable for application in many British and European locations. The two methods are applied to the major port of Portsmouth in Southern England and are critically compared.     

DOT2008A海面地形模型在我国邻近海域的精度评估

文中首先介绍了DOT2008A模型建立的原理和方法,利用我国48个长期验潮站19 a连续观测数据验证DOT2008A模型的精度,其均方差为0.118 m,残差的标准偏差为0.086 m;联合多源测高卫星建立的海面地形模型数据验证DOT2008A的精度,均方差为0.106 m,残差的标准偏差为0.099 5 m,且其残差分布图基本符合正态分布。从实验结果来看,DOT2008A模型在我国周边海域精度较高,其建立方法较为合理,转化应用价值较高;同时与多源测高卫星建立的海面地形比较结果来看,验证了自主建立的海面地形模型的正确性,对建立我国高精度海面地形模型具有重要的借鉴意义。     

A study of environmental constraints in the coastal harbor radiotelephone system

This paper presents a new study of the effects on communications within the coastal harbor system of such environmental factors as nonstationary signal propagation characteristics and nonstationary atmospheric noise. Propagation of signals during daylight hours is predominantly by ground-wave propagation over sea water. During the evening hours, sky-wave and ground-wave propagation takes place. The noise at receiving sites during daylight hours is predominantly set by the level of galactic or man-made noise some 40 to 45 dB above thermal. During the evening hours, the level of atmospheric noise may at times reach some 90 dB above thermal. For daylight hours, it is shown that usable quality will not be achieved for distances greater than 400 mi; while at night, usable quality will be achieved beyond 200 mi with less than 20-percent probability. The conditional distribution of intraarea signal-to-interference ratio at the receiving antenna is shown to be approximately lognormal with a standard deviation of 23 dB during the day and a standard deviation of 16 dB during the night, for an area of high atmospheric noise. It is also shown that channel frequency separations of greater than 9 kHz are necessary if the probability of detecting crosstalk is to be kept below 25 percent during interfering transmissions from the same coverage area under low noise conditions. The probability of detecting intelligible crosstalk from a eochannel interferer transmitting at night from a different coverage area located from 400 to 1200 mi away could be as high as 58 percent.     

Statistical estimates of characteristics of long-wave run-up on a beach

A run-up of irregular long sea waves on a beach with a constant slope is studied within the framework of the nonlinear shallow-water theory. This problem was solved earlier for deterministic waves, both periodic and pulse ones, using the approach based on the Legendre transform. Within this approach, it is possible to get an exact solution for the displacement of a moving shoreline in the case of irregular-wave run-up as well. It is used to determine statistical moments of run-up characteristics. It is shown that nonlinearity in a run-up wave does not affect the velocity moments of the shoreline motion but influences the moments of mobile shoreline displacement. In particular, the randomness of a wave field yields an increase in the average water level on the shore and decrease in standard deviation. The asymmetry calculated through the third moment is positive and increases with the amplitude growth. The kurtosis calculated through the fourth moment turns out to be positive at small amplitudes and negative at large ones. All this points to the advantage of the wave run-up on the shore as compared to a backwash at least for small-amplitude waves, even if an incident wave is a Gaussian stationary process with a zero mean. The probability of wave breaking during run-up and the applicability limits for the derived equations are discussed.     

南海北部海面风速概率分布特征

利用南海北部的浮标、石油平台观测的海面风资料，分析了0~200 km范围内，不同离岸距离站点的风速的概率分布特征。观测结果指出，各站平均风速一般最大值出现在冬季，最小值出现在夏季，具有明显的季节变化特征，并且平均风速随着离岸距离的增大也逐渐增大。对于离岸距离较近的区域（100 km以内），海面风基本符合双参数的Weibull分布，但对于100 km以外的海面风速概率分布与Weibull分布存在明显差异，随着离岸距离的增大，平均风速和风速标准偏差也相应增大。风速平均值与风速标准偏差的比值较小时，Weibull分布的偏斜度基本为正值，当比值较大时偏斜度转为负值。随着离岸距离的增大，出现与Weibull分布不一致的情况越来越多，且与对应的Weibull分布相比，其偏斜度越小，风速概率分布越不能用Weibull分布进行较好拟合。     

Extreme Statistics of Storm Surges in the Baltic Sea

Statistical analysis of the extreme values of the Baltic Sea level has been performed for a series of observations for 15–125 years at 13 tide gauge stations. It is shown that the empirical relation between value of extreme sea level rises or ebbs (caused by storm events) and its return period in the Baltic Sea can be well approximated by the Gumbel probability distribution. The maximum values of extreme floods/ebbs of the 100-year recurrence were observed in the Gulf of Finland and the Gulf of Riga. The two longest data series, observed in Stockholm and Vyborg over 125 years, have shown a significant deviation from the Gumbel distribution for the rarest events. Statistical analysis of the hourly sea level data series reveals some asymmetry in the variability of the Baltic Sea level. The probability of rises proved higher than that of ebbs. As for the magnitude of the 100-year recurrence surge, it considerably exceeded the magnitude of ebbs almost everywhere. This asymmetry effect can be attributed to the influence of low atmospheric pressure during storms. A statistical study of extreme values has also been applied to sea level series for Narva over the period of 1994–2000, which were simulated by the ROMS numerical model. Comparisons of the “simulated” and “observed” extreme sea level distributions show that the model reproduces quite satisfactorily extreme floods of “moderate” magnitude; however, it underestimates sea level changes for the most powerful storm surges.     

HY-2C卫星海面高度数据的质量分析

卫星海面高度数据对于监测全球海面高度具有重要的意义,所以卫星高度数据的定标和检验变得至关重要。海洋二号C（HY-2C）卫星是继海洋二号B卫星后的第二颗业务卫星,于2020年成功发射升空。然而,目前对HY-2C卫星高度计的数据质量了解甚少,所以对HY-2C卫星的海面高度数据进行质量分析具有重要的意义。本文以同期观测的HY-2B卫星和Jason-3卫星的地球物理数据（GDR）为参考,对HY-2C卫星遥感地球物理数据（SGDR）中的海面高度数据进行质量分析。结果显示,在星星交叉定标中使用3种常见的交叉定标插值方法对HY-2C卫星的海面高度异常数据进行自交叉点分析时,HY-2C卫星海面高度异常数据质量分析的结果不同。其中使用三次样条插值方法进行质量分析的结果最优,得到海平面高度异常差的平均值为0.03 cm,标准差为6.17 cm。此外,对HY-2C卫星和HY-2B卫星互交叉点海面高度异常差异的平均值为?0.47 cm,标准差为5.32 cm;HY-2C卫星SGDR与Jason-3卫星GDR的海面高度异常数据进行互交叉点分析,得到海平面高度异常差的平均值为?0.3 cm,标准差为5.32 cm,这些数据表明HY-2C卫星的测高精度与HY-2B卫星、Jason-3卫星一致。因此HY-2C高度计产品数据质量稳定,能满足海洋应用和科学研究的需要。     

风暴潮数值模拟中风应力拖曳系数的伴随法反演研究

借助伴随同化方法,利用实测水位资料,对空间分布的风应力拖曳系数做了反演研究.假定风应力拖曳系数具有空间分布特征,即在模拟海区中均匀选取一些独立点,利用这些独立点的风应力拖曳系数线性插值得到全场的风应力拖曳系数.同化实验结果表明,采用空间分布的风应力拖曳系数得到的模拟结果,明显优于将风应力拖曳系数取为常数和依照经验公式计...     

The statistics of HF sea-echo Doppler spectra

Several important statistical properties of the HF sea echo and its Doppler power spectrum, which are useful in optimizing the design of radar oceanographic experiments, are established. First- and second-order theories show that the echo signal (e.g., the voltage) should be Gaussian; this is confirmed with experimental surface-wave data i) by comparison of the normalized standard deviation of the power spectrum at a given frequency with its predicted value of unity, and ii) by cumulative distribution plots of measured spectral amplitudes on Rayleigh probability charts. The normalized standard deviation of the dominant absolute peak amplitudes of the power spectrum (which wander slightly in frequency) are shown from experimental data to besim 0.7for the first-order peaks andsim 0.5for the second-order peaks. The autocorrelation coefficient of the power spectra is derived from measured data and interpreted in terms of the spectral peak widths; from this information, the correlation time (or time between independent power spectrum samples) iS shown to besim 25-50s for radar frequencies above 7 MHz. All of these statistical quantities are observed to be independent of sea state, scattering cell size, and relatively independent of radar operating frequency. These quantities are then used to establish the statistical error (and confidence interval) for radar remote sensing of sea state, and it is shown, for example, that 14 power spectral samples result in a sample average whose rms error about the true mean is 1.0 dB.