INTERACTIONS BETWEEN WATER WAVES AND WINDS (I): co-existent system of wind wave and regular oscillatory wave
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A central question in this study is the evaluation and the improvement of the accuracy of wind-wave predictions in semi-enclosed seas. It was investigated how the parametrization of the wave models can be modified to provide accurate predictions in these specific areas. Furthermore, this work outlines how the physical inputs of the wave model such as the wind forcing and the bathymetry can affect wave predictions. An additional objective of this work is to assess the accuracy of the in-situ and remote field observations used in the calibration and validation processes of the numerical wave model. To examine these questions, wind-waves were simulated with the spectral wave model Simulating WAves Nearshore (SWAN) included in the Delft3D modelling package (Deltares, the Netherlands). Extensive calibration and validation of the wave model and its wind forcing were achieved by means of large datasets of in-situ and remote measurement technologies. Numerical predictions of wind-generated waves in two semi-enclosed seas, the Red Sea and the Bohai Sea were improved by means of modifications of the source term responsible of the generation of wave energy by wind in the action balance equation of the wave model. The findings provide support to the scientific community in the field of the operational oceanography. The outputs of the wave model for the Red Sea and the coastal waters of Jeddah were integrated into a coastal monitoring system. The wave model set up for the Bohai Sea is part of a Decision Support System for the Shandong peninsula. The two information systems provide hindcasts and forecasts of hydrodynamic parameters.
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Wave model
Significant wave height
Parametrization (atmospheric modeling)
Forcing (mathematics)
Wave height
Sea state
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A numerical simulation study is carried out over Indian Ocean using spectral wind-wave model “WAM.” The surface wind analysis data utilized in this study are generated by assimilation of satellite data in numerical weather prediction models. These winds are used for forcing the ocean WAve Model (WAM) and various spectral and significant wave parameters are simulated. The model simulated outputs viz. significant wave height, peak, and mean wave periods; mean wave and wind-wave directions; the swell wave height, frequency, and direction; frictional wind velocity, wave-induced stress, frequency spectrum, and the two-dimensional directional wave spectrum are presented. A detail analysis is performed to these parameters for assessing spatio-temporal variability for rough weather period (July 1–August 24, 1999). Further, the input wind and simulated waves are validated against ocean buoy observations. The time series spectral evolution of wind-wave in central Bay of Bengal is discussed. The comparison results of significant and spectral wave parameters with measured data co-locating in time and space are presented. The result reveals that the performance of third generation wave model is promising over Indian Ocean despite several limitations. Further, the coincidence and departure of simulated and observed waves are critically examined.
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Infragravity wave
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Since waves fluctuate continuously, the forecast of the wave energy is very important for the operation of the power system integrated with large-scale wave energy generations. Waves are driven by wind, so that the relationship between wind and wave is very useful in wave energy forecast. Hence, a wave energy forecast method based on the wind-wave coupling model is proposed in this paper. The wave is first divided into wind waves and swells. The correlation between wind and wind wave is analyzed, and a wind-wave coupling model is established using copula function. Based on the coupling model and the forecasted wind speed, the average wave height of the wind wave can be forecasted, while the time series method is used to forecast the average wave height of the swell. Combining the wind wave and the swell, the average wave height of the integrated wave is obtained and the wave energy can be forecasted. Using the measured wind and wave data from a real ocean, the day-ahead wave energy is forecasted by the proposed method. The forecast result is close to the measured data and the effectiveness of the proposed wave energy forecast method is validated.
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This paper investigates the utility of winds obtainable from a numerical weather prediction model for driving a spectral ocean-wave model in an operational mode. Wind inputs for two operational spectral wave models were analyzed with respect to observed winds at three locations in the Canadian east coast offshore. Also, significant wave heights obtainable from the two spectral models were evaluated against measured wave data at these locations. Based on this analysis, the importance of appropriate wind specification for operational wave analysis and forecasting is demonstrated.
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Wave model
Mode (computer interface)
Spectral Analysis
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Numerical models
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The ocean wave is one of the main marine disasters that have great effects on the ocean engineering. The research on the ocean waves can supply data for ocean engineering and protect it. In recent years, the results of numerical study have been an important basis for wave forecasting and engineering design. The full-spectral third-generation ocean wind-wave model, WAVEWATCH-Ⅲ, has been implemented in the Bohai Sea, the Yellow Sea and the East China Sea for investigating wind-wave characteristics. The QSCAT/NCEP blended wind data (0.5° resolution) from Colorado Research Associates 4 times daily were used to simulate the wind waves in two cold wave events in 1999 and 2000. Firstly, the results from WAVEWATCH-Ⅲ were tested, and the main factors that influence simulation were analyzed. Compared with the Janson-1 altimetric data, the capability of WAVEWATCH-Ⅲ for the selected region was validated. It is also shown that, during the course of the cold wave, the east and south water boundary of the selected region have little effects on the simulation of the significant wave heights, while the islands are important influencing factors, especially when the wave height value is small. Secondly, the characteristics of ocean waves in the region were studied. The directions of wind and wave are mainly the same during the cold wave events. The center of maximum wave height corresponds to that of maximum wind speed in the south Yellow Sea and the East China Sea. However, in the Bohai Sea and the north Yellow Sea, the center of maximum wave height is in the south to that of maximum wind speed, which is probably induced by the closeness of the sea regions. Finally, the response characteristics of wave spectra to the cold wave events were analyzed. In cold wave events, frequency and direction of ocean waves at certain point are centralized mostly when its wave energy is most. At the same time, the peak frequency is lowest. The response of the wave energy lags behind the variation of the wind speed, while the factors related to the lag time are uncertain.
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China sea
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This paper investigates the utility of winds obtainable from a numerical weather prediction model for driving a spectral ocean-wave model in an operational mode. Wind inputs for two operational spectral wave models were analyzed with respect to observed winds at three locations in the Canadian east coast offshore. Also, significant wave heights obtainable from the two spectral models were evaluated against measured wave data at these locations. Based on this analysis, the importance of appropriate wind specification for operational wave analysis and forecasting is demonstrated.
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Spectral Analysis
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East coast
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Two wind modes were developed and their results compared with data gathered during the Wangara experiment, so as to characterise their uncertainty. One of the models was adopted to generate the wind fields used as input to a second generation wave model. The relative error in the wind speed was considered in order to assess the uncertainties of the predictions of the significant wave height. Different time steps for the wind input were also used to determine their effect on the predicted significant wave height.
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ABSTRACT In recent years, the number of wave prediction models has proliferated. These models range from relatively simple parameterizations of significant wave height as a function of wind, duration and fetch to rather sophisticated solutions for the generation, propagation and dissipation of two dimensional wave spectra. It is sometimes suggested that any wave model will provide reasonable answers when properly applied, and that most of the deviations between measured waves and predicted waves can be explained by discrepancies between actual and estimated wind fields. Although almost certainly much of the error in wave prediction is related to problems in determining a wind field, this paper examines the specific question of whether or not there are differences among these models such that even if the wind field were perfectly specified, there would remain significant deviations among predicted waves. First, wave generation under uniform wind fields are compared using non-dimensional parameters. Then, the models are again compared under conditions of time varying, space varying wind fields and with irregular fetch boundaries. It is concluded that, in the open ocean with long duration, slowly varying weather system, most models produce rather similar results; however, near a coastal or in regions with rapidly varying weather systems rather marked differences can be expected from the use of different models. INTRODUCTION The need for wave data has increasingly led to the use of wave hindcast techniques to produce wave climates, and a number of major hindcast efforts are underway in the U. S. alone (Lazanoff, 1977; Ward et al., 1978; Vincent et al., 1978). Numerous techniques are available, ranging from significant wave techniques, in which wave parameters can be estimated from nomograms, to directional spectral models, which are usually run on largecore high-speed digital computers. Table I lists a sample of some of these techniques. An underlying assumption commonly made by practicing engineers is that each of the techniques will produce similar results when properly applied with correct wind input. It is the purpose of this paper to demonstrate that this is not always the case. Instead, various models can be shown to have theoretical differences which in climatological, as well as specific, applications might lead to significant discrepancies in estimates of sea state. Since all wave hindcasts begin with reconstruction of past wind fields from historical records a baseline error present in all wave estimates comes from inaccuracies in available meteorological data. Often it seems as though it is tacitly assumed by investigators that the wind error dominates the total error term in hindcast studies and hence that the absolute accuracy of the wave model is not all that important. A consequence of this might seem to be that, where available meteorological data is of high quality, a wave model of high quality should be used; but, where available meteorological data is of low quality (or sparse in time and space), a simple wave model will suffice.
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