湛江近海M2分潮的数值模拟

利用潮汐模型,在高分辨率的自适应曲线网格下,采用潮汐调和常数作为控制模拟精度的方法,模拟了洪江附近海域M2分潮的运动特征。模拟所得的潮汐调和常数同实测值相比,误差较小。根据模拟结果绘制的M2分潮的同潮图,揭示了湛江附近海域M2分潮振幅和迟角的分布特征以及M2分潮的传播和发展规律。模拟得到的M2分潮分别在涨憩、落憩、涨急和落急几个典型时刻的流场,揭示了湛江附近海域M2分潮潮流的分布特征及其运动规律。     

北部湾潮汐潮流的三维数值模拟

基于二阶湍流闭合模型计算涡动粘性系数的POM三维水动力模式,采用细网格,考虑6个岛屿、海底摩擦系数进行划片取值,模拟北部湾潮汐潮流.所得潮汐调和常数与81个实测站比较,绝对平均误差:K₁分潮振幅为46cm,迟角为9°;O₁分潮振幅为56cm,迟角为7°;M₂分潮振幅为62cm,迟角为15°.由模拟结果分析出该海区潮汐、潮流、余水位和潮余流,以及水平速度垂直分布等特征.     

Effect of Sea Level Variation on Tidal Characteristic Values for the East China Sea

1 .IntroductionTheglobalairtemperatureroseabout 0 .5～ 0 .6°Coverthepast 2 0thcentury ,andtheglobalmeansealevelincreasedbyabout2 0cmduringtheperiod .Theregionalmeansealevelriseswiththerisingglobalmeansealevel.Zuoetal.( 1 997)indicatedthatthemeanrisingrateofabsolutemeansealevelalongtheChinacoastontheassumptionofunifiedisostaticdatumis 2mm a .Woodworth( 1 999)analyzedsealevelspanning 1 76 8tothepresentinLiverpool,andobtainedaseculartrendforheperiodupto 1 880of0 .39± 0 .1 7mm a ,andatrendfort…     

长江口外海域三维水动力模拟结果及与观测的比较

Base on ECOMSED model, a theree-dimensional hydrodynamic model is developed in the offshore area near the Changjing Estuary in the East China Sea. This model in driven by tide and wind,as well as inflow and outflowcurrents such as Kuroshio,Changjing runoff. The horizontal resolution is 1/20_°. There have 11 layers on the verticaldirection. The numerical results of 4 main constituents of tide(M²,S²,K¹,O¹)and currents are in good agreement with observation data. Compared with 20 gauge stations,the mean absolute erroe between the caluclated M² tidal amplitude and the observed oned is only 6.72cm; the mean absolute error of phased-lag is 5.23_°.For S²,the mean absolute errors of amplitude and phased-lag are 3.67cm and 7.21_°,respectively. The mean absolute errors of amplitude and phased-lag for K¹ are 3.25cm and 6.63_° For O¹,the mean absolute error of calculation and observation is relatively small, amwith observation data measured during Aug., 2006 in the East China Sea.The correlation coeffiients of current between simulation and observation are greater than 0.75 generally. The three-dimensional hydrodynamic model develiped by this paper can well describe the characters of elevation and current in the offshore near the Changjiang Estuary and can be used as hydrodynamic background to simulate the suspend sediment transport in this sea area.     

西北太平洋的一种潮汐数值同化模型

利用FVCOM海洋数值模式,在球坐标系统下考虑非线性效应和天体引潮力的影响,基于非结构的三角形网格建立了包括中国近海、日本海、鄂霍次科海和部分西北太平洋海域的高分辨率海洋潮汐数值模型,并采用趋近法同化84个沿岸验潮站的观测资料。模拟结果与175个验潮站的实测结果拟合良好,M₂,S₂,K₁,O₁四个主要分潮振幅和迟角的绝对平均误差分别为4.0 cm和5.6°,2.4 cm和7.5°,2.6 cm和6.3°,1.5 cm和5.0°。依据调和分析结果给出了4个主要分潮的同潮图分布,得到8个半日分潮和5个全日分潮的无潮点,证实了宗谷海峡全日潮无潮点的存在,首次模拟得到津轻海峡的全日潮无潮点;还给出了整个计算海域内最大可能潮差和潮汐余水位的分布特征。     

Numerical simulation of fluctuation and undulation of the thermo-cline under tide (tidal current) action in the Bohai Sea

Besides seasonal variation, instantaneous variation of thermal layer will occur under the effects of tide, tidal current and wind disturbance. In this study the numerical simulation has been first carried out on fluctuation and undulation of thermal layer under influence of tide (simultaneous input of 8 tidal components). The study reveals the geographic distribution of thermal layer fluctuation in the entire study region and temporal and spatial variations of the undulation in tidal period superposing on the fluctuation. Especially, the wave with large amplitude simulated is consistent with observation in the channal and the sea areas with a convex coastline and complex variation of depth, internal relations of tide, tidal current, residual current as well as the factors such as geography, and the fluctuation of thermal layer is induced by residual current due to unsymmetry which occurs as a result of the tidal movement in lower layer influenced by friction and geography, meanwhile, analysis indicates     

青岛海湾大桥对胶州湾潮汐、潮流及余环流的影响预测——Ⅰ.胶州湾及邻近海域的潮流

根据崂山头、朝连岛、灵山岛一个月的潮位资料,采用三角形网格的分步杂交方法,建立了胶州湾及邻近海域的二维变边界潮流数值模型。并模拟了大、中、小潮三种潮汛条件下的潮流场,水位场及余流场。得出了胶州湾高潮水域面积、潮间带面积,湾口累积流通量等有关参数。     

东海M2分潮模拟中开边界条件的探讨

基于POM模式，采用第一类水位、流速和Flather（1976）3种开边界条件，模拟了东海的M2分潮．结果表明，在这3种开边界条件下，均能成功地模拟M2分潮的传播特征，以及在该海区内的三个半无潮点．计算结果与实测的较吻合，并且在Flather开边界条件下，模拟的振幅和迟角与实测资料的偏差分别为5．62cm和7．90°，效果最好．这也说明Flather开边界条件是潮汐模拟当中较可取的一种开边界条件．     

基于z坐标海洋模式的全球正压潮波数值模拟研究

The performance of a z-level ocean model, the Modular Ocean Model Version 4(MOM4), is evaluated in terms of simulating the global tide with different horizontal resolutions commonly used by climate models. The performance using various sets of model topography is evaluated. The results show that the optimum filter radius can improve the simulated co-tidal phase and that better topography quality can lead to smaller rootmean square(RMS) error in simulated tides. Sensitivity experiments are conducted to test the impact of spatial resolutions. It is shown that the model results are sensitive to horizontal resolutions. The calculated absolute mean errors of the co-tidal phase show that simulations with horizontal resolutions of 0.5° and 0.25° have about 35.5% higher performance compared that with 1° model resolution. An internal tide drag parameterization is adopted to reduce large system errors in the tidal amplitude. The RMS error of the best tuned 0.25° model compared with the satellite-altimetry-constrained model TPXO7.2 is 8.5 cm for M_2. The tidal energy fluxes of M_2 and K_1 are calculated and their patterns are in good agreement with those from the TPXO7.2. The correlation coefficients of the tidal energy fluxes can be used as an important index to evaluate a model skill.     

基于长期观测的辽东湾口东部海域水动力特征研究

辽东湾口东部海域是辽东湾与渤海中部进行物质和能量交换的主要通道之一。本文利用坐底式海床基平台获取的近8个月的水动力连续观测资料,通过谱分析和调和分析方法对该海域的潮汐、潮流特征进行分析,并讨论了余流及底层温度的季节变化规律。研究结果表明:该海域潮汐属于不规则半日潮,平均潮差为0.95 m,最大可能潮差为2.27 m。潮流属于不规则半日潮流,M₂分潮流为其优势分潮流。主要分潮流运动形式为往复流,最大流速方向为西南-东北向。余流的季节性特征较为明显:秋季,余流流速在中层达到最大,流向以西南向为主;冬季,余流流速垂向变化较小,并呈西南偏西向流动;春季,流速随深度增加而减小,流向从表层至底层呈现逆时针旋转的特征。受底层潮流、水平温度梯度及海面温度日变化的影响,底层温度表现出短期的高频变化特征:秋季,短期振荡以半日周期信号为主;冬季,全日周期信号较为显著;春季,短期振荡的现象较弱。     

全球大洋潮汐模式在北印度洋潮汐预报准确性的评估

为评估DTU10、TPXO8、GOT00.2和NAO.99b 4个全球大洋潮汐模式对北印度洋潮汐的预报能力,采用英国海洋资料中心提供的海区中部和沿岸站潮汐调和常数资料,检验了这些模式4个主要分潮(M_2、S_2、K_1、O_1)的准确度。它们的各分潮调和常数资料准确度都比较高,振幅绝均差的最大值仅5.61 cm,迟角绝均差的最大值仅9.13°。这些模式的调和常数给出潮波传播特征差别不大。基于这些模式提供的调和常数,分别建立了北印度洋4、8和16分潮潮汐预报模型,将预报结果与中国海事服务网提供的沿岸24个站潮汐表资料进行对比。各模式的8分潮(M_2、S_2、N_2、K_2、K_1、O_1、P_1、Q_1)潮汐预报模型均优于4分潮(M_2、S_2、K_1、O_1)潮汐预报模型,NAO.99b模式可以提供16分潮(M_2、S_2、N_2、K_2、K_1、O_1、P_1、Q_1、MU_2、NU_2、T_2、L_2、2N_2、J_1、M1、OO_1)潮汐预报模型,但是对预报结果改善不明显;在各模式中,GOT00.2模式的8分潮潮汐预报模型对北印度洋沿岸的预报效果最好,平均绝均差为14.97 cm。     

环台湾岛海域全日分潮的特征和潮汐、潮流的综合性质

用97版POC海洋模式，对环台湾岛海域的全日分潮和整个潮汐，潮流综合特征进行三维数值研究。研究海域全日分潮是由太平洋传入的，且来自台湾岛北部海区传入的潮波穿越海峡。由吕宋海峡传入的全日分潮对维持南海的潮运动起着重要作用。全日分潮最大流同时线分布表层有5个圆流点，其中4个本文首次得到。台湾海峡及其以北海区和台湾东部洋区为不规则半日潮区，台湾东南为全日分潮为主的混合潮区。台湾岛北部为气旋式余流涡旋区，环绕台浅滩为反气旋余流涡旋区，澎湖水道开始的转向流预示着海峡及其邻近海区的涨潮流或落潮流的来临。     

永暑礁海区潮汐海流特征分析

将永暑礁水域1992年逐时潮位和1993年5月-2002年5月各航次的海流及2002年海面逐时风等观测资料进行统计和分析,讨论该岛礁水域潮汐和海流变化特征并对综合极值海流进行初步估算。结果表明,该岛礁水域全日分潮大于半日分潮,潮汐性质属不正规日潮,最大可能潮差较大。春季该岛礁水域实测海流变化较大;最大流速75cm／s。潮流性质为不正规日潮流,随水深的增加日潮流的性质有所减弱;主要日分潮流多作顺时针方向旋转,主要半日潮流则作反时针方向旋转。春季余流较稳定,速度在10cm／s左右,流向多为偏S-SW向。初步探讨了表层不同方位上综合极值海流的分布,不同方位上综合极值海流相差较大,NE、SSW方位上综合极值海流占份量较显著,显示出季风海流的特征。     

Evaluation of tidal error in altimetry data in the Asian marginal seas

The magnitude and geographical distribution of the error in the Archiving, Validation and Interpretation of Satellite Oceanographic data (AVISO) altimetry data associated with tidal correction around Asian marginal seas has been revealed. The errors were evaluated by harmonic analysis of the AVISO corrected sea surface heights data (CorSSH). Errors of more than 15 cm of tidal correction were recognized in the western and northern parts of the Yellow Sea, Celebes Sea, Kuril Islands, and the northwestern part of the Okhotsk Sea. It was found that the CorSSH and sea level anomaly (SLA) data downloaded from the AVISO are not available for direct use in those marginal seas. To reduce the tidal correction error, the harmonic constants calculated from the latest tide model and regional tide model were applied as the tidal correction of the Altimetry data. The tidal errors in the Yellow Sea and the northwestern part of the Okhotsk Sea were reduced by approximately 20 cm and 10 cm, respectively. Root mean square differences between the harmonic constants derived from tide models and those derived from altimetry data were calculated. The root mean square differences were large in the Yellow and the Okhotsk Seas. Root sum squares for four principal tidal constituents in the Yellow and East China Seas and Okhotsk Sea were 7.72 cm and 8.36 cm, respectively.     

东印度洋海域最优深度基准面模型构建

利用东印度洋海域周边长期验潮站实测数据、TOPEX/Poseidon等系列卫星测高反演结果,评估了DTU10,EOT11a,FES2014,GOT4.8,OSU12和TPXO8六种全球潮汐模型精度,根据卫星测高结果给出了浅水分潮改正量和长周期分潮改正量的经验模型,又在此基础上分析并构建了研究区域精度最优的深度基准面模型。考虑到全球潮汐模型在近岸的影响因素及验潮站位置,将13个验潮站分成开阔海域与近海海域两类,与潮汐模型的对比,结果表明,DTU10和FES2014模型分别在开阔海域和近海海域精度最优。根据潮汐模型在不同分潮处的精度,如EOT11a模型在O1和K1分潮处精度较高,DTU10在N2,M2,S2和K2分潮处精度较高等,分别构建了开阔海域与近海海域的组合深度基准面模型,计算得知误差分别为11.33和20.95 cm,其精度显著提高。     

基于高频地波雷达资料的海南中东部近海表层海流特征

利用海南中东部近海海域高频地波雷达观测得到的2019年4月—2020年3月表层海流资料进行潮流调和分析和余流分析。结果表明: 海南中东部近海海域以不规则半日潮流为主, 半日分潮M₂和S₂以往复流为主, 全日分潮O₁、K₁以顺时针旋转流为主, M₂、S₂、O₁、K₁分潮最大潮流流速的比为1 : 0.51 : 0.60 : 0.65, M₂为最主要分潮。最大可能潮流流速分布从西南方向向东北方向逐步增大, 最大值为35cm·s^-1。余流受东亚季风影响较大, 季节变化特征显著, 呈夏季形态(6月—8月)、冬季形态(9月—次年2月)和过渡形态(3月—5月)。夏季形态流向东北, 平均流速29cm·s^-1; 冬季形态持续时间最长, 流向西南, 平均流速36cm·s^-1, 大于夏季形态; 过渡形态为冬季形态向夏季形态的转变期, 流向分布较复杂, 平均流速13cm·s^-1, 明显小于夏季和冬季形态。从全年来看, 西南向流动的时间最长、流速最大, 海南中东部表层海水物质输运自东北向西南。     

渤海潮波系统的数值模拟

利用二维非线性潮波方程组,讨论了渤黄海主要分潮(全日潮、半日潮及浅水分潮) 数值模拟中的有关问题。数值模拟中同时考虑了4个主要分潮(M2,S2,K1,O1)和两个浅水分潮(M4,MS4)。分析表明,在渤黄海潮波系统数值模拟中,稳定后选取14 d的数值模拟结果进行调和分析能够取得最佳(最合理)的调和分析结果。计算出调和常数的模拟值与实测值之差的绝对平均值:M2分潮的振幅差为4cm,迟角差为3.3°,S2分潮的振幅差为2cm,迟角差为4.2°,K1 分潮的振幅差为1cm,迟角差为3.7°,O1分潮的振幅差为2 cm,迟角差为5.5°。实验结果较好地体现了渤黄海潮波系统的特征。     

渤、黄、东海三维潮波运动数值模拟

采用POM三维海流数值模式模拟渤、黄、东海潮波运动。所得潮汐调和常数与77个测站的观测值的平均绝对误差：m1振幅1．92cm,迟角4．39°;M2振幅4．70cm,迟角5．08°。模拟结果显示M2分潮流共存在8个圆流点,m1岁潮流共存在9个圆流点。其中,M2分潮流在舟山群岛附近与m1分潮流在黄海北部和台湾海峡谷存在一个圆流点,这三个圆流点是本文数值模拟所首次显示的,需进一步的观测验证它们实际存在与否。模式还得出湍流涡动系数分布。     

Comparison of sea surface heights observed by TOPEX altimeter with sea level data at Chichijima

The sea surface heights (SSHs) observed by the TOPEX altimeter are compared with tide gauge data at Chichijima in Ogasawara (Bonin) Islands and hydrographic data taken around the islands, in order to quantitatively verify the altimeter observations and oceanic tide corrections by three tide models proposed by Cartwright and Ray (1991), Rayet al. (1994), and Maet al. (1994). First, performance of the new tide models is assessed by comparing tidal variations consisting of diurnal and semi-diurnal constituents with the tide gauge data at Chichijima. The tide model proposed by Rayet al. gives the smallest root-mean-squared (rms) difference of 2.61 cm. Errors in amplitude and phase in each tide model are evaluated by spectral analysis. The TOPEX SSHs corrected by the tide models are compared with sea level data at Chichijima. A long-term variation of a period of about 1 year is found in the residual between the SSHs and the Chichijima sea levels. This variation is also found in the difference between the dynamic height anomalies calculated from hydrographic data around the island and the Chichijima sea levels. By subtracting the long-term variation, the rms difference between the TOPEX SSHs and the Chichijima sea levels is reduced to about 4 cm and the slope of the regression line is improved to unity. The residual shows variations related to aliasing caused by incompleteness of the ocean tide correction with the repeat cycle of the altimeter observation.     

A numerical study of a tide with four harmonic constituents at the open boundary

The tidal current in Kagoshima Bay is simulated by the two-dimensional subdomain finite-element method. At the open boundary, the sea level is forced to be oscillatory with a linear combination of the four harmonic constituents (M2, S2, K1, O1) of the tide. A calculation having only M2 sea level at the open boundary is also performed and the harmonic constants of M2 are compared with those calculated by the four components.In the calculated velocity vector, a large difference between the two maxima or the two minima in one day appears when the vector is directed to the open sea. On the other hand, when it is directed into the bay, the two extreme velocities are almost equal. In tide-killer residual flow, the flow pattern is almost independent of the tidal age; however, the absolute value of the current velocity depends on the tidal age. The pattern is nearly the same as that calculated by giving only M2 sea level at the open boundary.In relation to the nonlinear interaction, the kinetic energy ratio KER is defined by the ratio of kinetic energy of the induced harmonic components to that of harmonic constituents given at the open boundary. KER is large where the tidal current is disturbed by obstacles,e.g. along the west coast at the mouth of the bay and in the southern sea of Mt. Sakurajima. The distribution of KER seems to be independent of the number of harmonic constituents (one or four) given at the open boundary. The difference of kinetic energy of the M2 tidal constituent between the two calculations.i.e. with the open boundary conditions of four components (M2, S2, K1, O1) and of a single component (M2), is found to be large where the current velocity is large.