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1.
In this paper, first we introduce the wave run-up scale which describes the degree of wave run-up based on observed sea conditions near and on a coastal structure. Then, we introduce a simple method which can be used for daily forecast of wave run-up on a coastal structure. The method derives a multiple linear regression equation between wave run-up scale and offshore wind and wave parameters using long-term photographical observation of wave run-up and offshore wave forecasting model results. The derived regression equation then can be used for forecasting the run-up scale using the offshore wave forecasting model results. To test the implementation of the method, wave run-up scales were observed at four breakwaters in the East Coast of Korea for 9 consecutive months in 2008. The data for the first 6 months were used to derive multiple linear regression equations, which were then validated using the run-up scale data for the remaining 3 months and the corresponding offshore wave forecasting model results. A comparison with an engineering formula for wave run-up is also made. It is found that this method can be used for daily forecast and warning of wave run-up on a coastal structure with reasonable accuracy. 相似文献
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The sea-surface height (SSH) signatures of internal tides extracted from the TOPEX/Poseidon (T/P) altimeter data along satellite tracks are fitted with superposition of several plane waves which have different wavenumber vectors. The key problem of plane wave fitting with iterative method is how to determine the initial value of wavenumber of each plane wave. The previous solving method is to analyze the internal tidal SSH signatures along each track with wavenumber spectrum. But it is found that the problem cannot be solved completely with the wavenumber spectrum analysis method only. The method based on the combination of wavenumber spectrum analysis method and the exhaustive method is proposed to determine the initial values of wavenumbers for iteration. Numerical results indicate that the proposed method is not only reasonable and feasible but also better than the previous method. The proposed method is an improvement of the previous one, which is beneficial to improving the precision of plane wave fitting of the T/P internal tidal SSH signatures and deepening the understanding of the internal tides in ocean. 相似文献
3.
By analysing the scatter diagrams of characteristic the wave height H and the period T on the basis of instrumental data from various ocean wave stations, we found that the conditional expectation and standard deviation of wave period for a given wave height can be better predicted by using the equations of normal linear regression rather than by those based on the log- normal law. The latter was implied in Ochi' s bivariate log-normal model(Ochi. 1978) for the long-term joint distribution of H and T. With the expectation and standard deviation predicted by the normal linear regression equations and applying proper types of distribution, we have obtained the conditional distribution of T for given H. Then combining this conditional P(T / H) with long-term marginal distribution of the wave height P(H) we establish a new parameterized model for the long-term joint distribution P(H,T). As an example of the application of the new model we give a method for estimating wave period associated with an extreme w 相似文献
4.
The variational assimilation method has been examined for ability of reconstructing mesoscale features in altimeter data using a simple dynamic model. A one-dimensional, two-layer Rossby wave model in a cross-track channel has been chosen. The simulated data are constructed from a theoretical solution, which is composed of any combination of two normal vertical (barotropic and baroclinic) modes. The data are collected along tracks and with repeat periods similar to those of the Geosat altimeter. The phase space of control variables is composed of initial and boundary conditions. A cost function is defined to measure differences between the simulated data and the model solution. Regularization (smoothing) terms are also included in the cost function in the form of secon-order spatial and time derivatives of the solution. In this paper, two potential problems existing in the altimeter data assimilation are addressed: one is low cross-track resolution, and the other is vertical projection of the data measured at the sea surface. A succesful metho is developed for reconstructing Rossby waves with wavelengths as short as twice the track intervals for any combination of two vertical modes. A key component to efficient assimilation is a preparation step prior to the actual variational assimilation: a uniform ratio of pressure amplitudes in the two layers is included as an optimization parameter. Starting with the first guess from the preparation step, the variational method is carried out based on adjoint equations without such constraint. Separation of the control variables into the two subsets of the initial and the boundary conditions is found useful. Characteristics of the Hessian matrix are related to the performance of this technique. The method developed for the linear system implies steps to be included in data assimilation for nonlinear meanders and eddies in a major current system as well. 相似文献
5.
利用美国NOAA/NCEP环境模拟中心海洋模拟小组近年新开发的一个准业务化的海浪数值模式WAVEWATCH Ⅲ(以下简称WWATCH),以每天4次的NOAA/NCEP再分析风场资料为输入,模拟了1996年的南海海域的海面风浪场,通过分析TOPEX/Poseidon(以下简称T/P)高度计的上升和下降轨道在南海海域的交叉点位置处的风、浪观测资料与NCEP风场和WWATCH模式模拟的有效波高大小,可以看出,NCEP风场基本与T/P高度计的风速观测结果一致,相应的模式模拟的有效波高也基本与卫星高度计的有效波高观测结果相一致,但从空间上看,在计算区域中心附近海域的结果一致性较好,靠近计算边界附近海域的结果相对较差,但这种因边界而影响模拟结果的范围很有限;从时间上看,冬季风期间的结果一致性较好,而夏季风期间的结果偏小的趋势明显,并且这种偏小主要出现在夏季风期间的极小风速值附近。 相似文献
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基于浮标数据的卫星雷达高度计海浪波高数据评价与校正 总被引：1，自引：1，他引：0
卫星雷达高度计是海浪有效波高（significant wave height,SWH）观测的重要手段之一,本文利用时空匹配方法对T/P、Jason-1、Envisat、Jason-2、Cryosat-2和HY-2A共6颗卫星雷达高度计SWH数据与NDBC（National Data Buoy Center,NDBC）浮标SWH数据进行对比验证,并对雷达高度计SWH数据进行校正。全部卫星雷达高度计SWH数据时间跨度为1992年9月25日到2015年9月1日,对比验证NDBC浮标共53个,包括7个大洋浮标。精度评价发现除T/P外,各卫星雷达高度计SWH的RMSE都在0.4~0.5 m之间,经过校正后,RMSE都有显著下降,下降程度最大为13.82%;对于大洋浮标,评价结果RMSE在0.20~0.28 m之间,结果明显优于全部NDBC浮标的精度评价结果;HY-2A卫星雷达高度计SWH在经过校正后数据质量与国外其他5颗卫星雷达高度计SWH数据质量差异较小。 相似文献
8.
海洋多道地震数据建模和成像是获取洋壳速度和构造信息的重要手段。海水层的存在使得多道地震拖缆接收到的折射波走时信息仅仅存在于较远的炮检距, 近炮检距被强振幅海底反射波覆盖, 制约了走时数据拾取和反演效果。本文基于波动方程的Kirchhoff积分法, 成功实现了多道地震数据向下延拓, 获取到了更大炮检距区间的初至折射波走时拾取, 并将其应用于洋中脊新生洋壳2A/2B层的合成多道地震数据走时反演。比较向下延拓前后的走时拾取范围及走时反演结果表明, 向下延拓法能够保持地震波场的运动学和动力学特征不变, 在共炮集数据的更大炮检距范围内进行初至折射走时拾取, 从而增加反演的数据选择和浅层射线覆盖, 反演结果能更加准确地分辨出洋壳2A/2B层界面, 并得到更高的分辨率和更准确的速度结构剖面。 相似文献
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The development of a definitive predictive model that accurately accounts for the nonlinear hydrodynamics and structural response behavior observed in arrays of closely spaced risers on deep water structures will require a more detailed understanding of this fluid–structure interaction. Through the analysis and interpretation of data from model basin tests on single and paired tandem cylinder configurations this study is directed at uncovering the nature of some aspects of this nonlinear response behavior using an orthogonal third-order Volterra technique that can delineate between linear, quadratic and cubic nonlinear frequency dependent behavior. As part of the analysis procedure the data was organized in input–output pairs that would provide logical groupings of the measured quantities. The data pairs presented in this study include wave excitation and inline cylinder displacement, wave excitation and transverse cylinder displacement, wave excitation and inline reaction force, and, upstream cylinder and downstream cylinder response. This information is presented in terms of spectral and coherence plots. The single cylinder data is presented as a means to contrast the behavior of the tandem cylinders. Both configurations were analyzed at two different pretensions adding another dimension to this investigation. It is shown that although a primary variable such as displacement may be more easily measured, pretension and force measurements provide an important key to our understanding of this difficult problem. 相似文献
10.
本文利用TerraSAR-X(TSX)卫星于2010年4月22日在南海东沙岛附近海域获取的数据进行海洋内孤立波动力要素和海表流速信息的提取研究。基于TSX数据的后向散射强度信息,利用经验模态分解法得到内孤立波半波宽度,再利用两层模型法和参数化法计算得到内孤立波振幅和相速度。反演结果显示,利用参数化方法得到的振幅(约21~39 m)和两层模型法得到的相速度(约1.07 m/s)与历史实测资料较为一致。进而利用TSX的顺轨干涉数据获取研究海域内的多普勒速度,再分别采用M4S模型法和直接分离法处理,进而提取海表流速。结果显示,两种方法得到的海表流速的全场平均值较为一致,均为1.10 m/s左右。M4S模型法对流速最大值的改变量较大而直接分离法对流速最小值的改变量较大。M4S模型对内孤立波波峰线区域海表流速的修正大于无内孤立波的海域。最后,基于KdV方程计算得到内孤立波引起的表面流的流速约为0.28 m/s,对反演出的海表流速贡献占比23%。 相似文献
11.
Surface water wave elevations and kinematics from four unidirectional irregular wave trains, with a Pierson and Moskowitz or JONSWAP random wave spectrum, were measured in the laboratory using resistance wave probes and a laser Doppler anemometer. The wave elevation data, velocity time series, extreme (largest) wave horizontal velocity profiles and extreme wave acceleration fields are compared with the predictions of a new wave kinematics model, named the hybrid wave model. Irregular waves are commonly viewed as the summation of many linear wave components of different frequencies, but more accurate predictions of downstream surface elevations (wave evolution) and wave kinematics are attained by considering the non-linear interactions among wave components. The hybrid wave model incorporates these non-linear wave component interactions, and its wave evolution predictions and kinematics estimates are compared with laboratory measurements in this study. Linear random wave theory, Wheeler stretching and linear extrapolation wave kinematic prediction techniques are also compared. Comparisons between measurements and hybrid wave model estimates demonstrate its improved capability to predict velocity and acceleration fields and wave evolution in two-dimensional irregular waves. 相似文献
12.
Compared to single-polarization synthetic aperture radar(SAR) data, fully polarimetric SAR data can provide more detailed information of the sea surface, which is important for applications such as shallow sea topography detection. The Gaofen-3 satellite provides abundant polarimetric SAR data for ocean research. In this paper, a shallow sea topography detection method was proposed based on fully polarimetric Gaofen-3 SAR data. This method considers swell patterns and only requires SAR data and ... 相似文献
13.
0414号"云娜"台风浪数值试验 总被引：3，自引：0，他引：3
利用美国NOAA/NCEP开发的海浪数值模式WAVEWATCHⅢ。以每天4次的NOAA/NCEP再分析风场资料为输入,模拟了2004年8月8~12日西北太平洋海域的0414号“云娜”台风引起的海浪。通过分析TOPEX/Poseidon(以下简称T/P)高度计的星下轨迹浪观测资料和WAVEWATCHⅢ模式后报的有效波高大小,可以看出模式能够较好地模拟台风浪。 相似文献
14.
An ensemble optimal interpolation (EnOI) data assimilation method is applied in the BCC_CSM1.1 to investigate the impact of ocean data assimilations on seasonal forecasts in an idealized twin experiment framework. Pseudo-observations of sea surface temperature (SST), sea surface height (SSH), sea surface salinity (SSS), temperature and salinity (T/S) profiles were first generated in a free model run. Then, a series of sensitivity tests initialized with predefined bias were conducted for a one-year period; this involved a free run (CTR) and seven assimilation runs. These tests allowed us to check the analysis field accuracy against the “truth”. As expected, data assimilation improved all investigated quantities; the joint assimilation of all variables gave more improved results than assimilating them separately. One-year predictions initialized from the seven runs and CTR were then conducted and compared. The forecasts initialized from joint assimilation of surface data produced comparable SST root mean square errors to that from assimilation of T/S profiles, but the assimilation of T/S profiles is crucial to reduce subsurface deficiencies. The ocean surface currents in the tropics were better predicted when initial conditions produced by assimilating T/S profiles, while surface data assimilation became more important at higher latitudes, particularly near the western boundary currents. The predictions of ocean heat content and mixed layer depth are significantly improved initialized from the joint assimilation of all the variables. Finally, a central Pacific El Ni?o was well predicted from the joint assimilation of surface data, indicating the importance of joint assimilation of SST, SSH, and SSS for ENSO predictions. 相似文献
15.
A new global archive of wind wave characteristics has been developed based on Voluntary Observing Ship (VOS) data for the period of 1888–2015. In addition to the basic meteorological variables, we have derived the records of visually observed heights, periods, and wind sea and swell directions. The main parameters have been supplemented by significant wave height and dominant period estimates, as well as wave geometry characteristics: steepness, wave age, and wavelength. Multistage quality control has been applied to correct or eliminate spurious values. Data are presented as individual records for every month and as original monthly means fields for every parameter. Easy access and use, along with representative data, make the new archive particularly special and applicable in different ways without any additional preprocessing. Visual wave observations assimilated in the new archive can be used to develop global and regional climatologies, estimate extreme wave characteristics and long-term trends in wave climate, verify and compare them with satellite measurements and model analysis, and test the theoretical laws of ocean wave development and propagation. 相似文献
16.
This paper presents a three-dimensional analytic linear wave solution for surface gravity wave propagation over a sloping bottom that is valid for small, but realistic, slopes. The sloping-bottom linear model is compared to published laboratory data and to predictions of two-dimensional, constant-bottom nonlinear theories. The model is shown to describe the measured wave-height growth in the wave transformation region up to a limiting local Ursell number Ur of 0.35-1.0, depending on the wave type, although, as a linear model, it does not predict the harmonics observed in that range. For Ur<0.35, the harmonics can generally be neglected and the sloping-bottom linear theory agrees closely with both the published wave-height data and third-order Stokes nonlinear theory. As a three-dimensional linear model, superposition can be invoked to synthesize and relate wave structure in the transformation region to complex incident ocean spectra with both wind wave and swell components that arrive with a range of incidence angles. As such, the sloping-bottom linear model presented here should be a convenient useful tool for ocean modeling through a significant portion of the wave transformation region 相似文献
17.
主动源海底地震仪探测在海底结构的研究中发挥着重要作用, 其中转换横波数据模拟为研究海底构造和物质属性提供了精确依据。本文针对现行转换横波模拟技术存在的步骤繁琐、难以确保最优解和无法进行非唯一性分析等问题进行研究, 提出了基于模型解空间和目标函数的模拟技术, 形成了主动源转换横波数据模拟的新方法, 该方法可借助计算机程序实现结构模拟的自动化。在南海西北陆缘的西沙地块OBS2013-3测线上对该方法进行验证, 分别利用单台PPS震相和全体台站的PSS震相走时数据进行模拟试验。结果表明, 本文的方法能够提供对于最优模型的快速、准确搜索和非唯一性范围的估计。这一方法有助于提高主动源海底地震仪转换横波数据模拟的效率, 并为结果的可靠性和稳定性提供更好的保障。 相似文献
18.
建立了求解一维全非线性Green-Naghdi水波方程的中心有限体积/有限差分混合数值格式。采用结构化网格对守恒形式的控制方程进行离散和积分,界面数值通量采用有限体积法计算,剩余项则采用中心有限差分格式求解。其中,采用中心迎风有限体积格式计算控制体界面数值通量,并结合界面变量的线性重构方法,使其在空间上具有四阶精度,通过引入静压重构技术和波浪破碎指标使模型具备处理海岸水-陆动边界及波浪破碎的能力。时间积分则采用具有总时间变差减小(Total Variation Diminishing,TVD)性质的三阶龙格-库塔法进行。应用该模型对孤立波在常水深和斜坡海岸上的传播过程及规则波跨越潜堤传播的实验进行了数值模型研究,数值计算同解析解及实验数据吻合良好。 相似文献
19.
Qiu Dahong Zhou Yuanheng Jia Ying Professor Dept. of Civil Engineering Dalian University of Technology Dalian Lecturer Dept. of Civil Engineering Dalian University of Technology Dalian 《中国海洋工程》1992,(1)
Based on the 1st order cnoidal wave theory, the wave diffraction around the pier group inshallow water is studied in this paper. The formulas for calculating the nonlinear wave forces are also presented here. In order to verify the theoretical results, model tests are conducted in the wave flume in The State Key Laboratory of Coastal and Offshore Engineering located in Dalian University of Technology. The range of the wave parameters in the experiments is characteristic wave period T g/d~(1/2) = 8.08- 22.86, characteristic wave height H/ d= 0.1 ~ 0.45. The results obtained from the experiments agree with the theoretical results quite well. It is shown that, in shallow water the nonlinear wave forces acting on a pier group are greater than those calculated by linear wave theory, the value of increment in wave force increases with the increases of the nonlinearity of the wave. In the wave range studied in this paper, the nonlinear wave force can reach over 4 times the force calculatecd by linear wave theory. Thus, it is suggested that, when Tg / d~(1/2)> 8, the wave force on the piers in the pier group in shallow water should be calculated by using the cnoidal wave theory. 相似文献
20.
Shutang Zhu 《Ocean Engineering》1999,26(12):535
This paper presents a transfer function method (TFM) which can separate a regular wave field into incident and reflected waves based on the linear wave theory. The TFM uses specific transfer functions and corresponding convolution integrals to separate time series data measured in a combined partial standing wave system into incident and reflected waves. After this separation, estimation of the reflection coefficient becomes very easy. All manipulations have been performed in time domain. Furthermore, this method does not involve the calculation of wave heights and/or phase differences. The present method is demonstrated through numerical sample and physical model experiments carried out in a wave flume. Compared with other methods, the TFM gives much better estimates of the incident wave heights for physical model experiments in this study. 相似文献