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1.
It is traditionally assumed that the relationship between wave steepness and wave age is independent of the wind wave growth state. In fact, the traditional relationship can not describe the whole course of wind wave growth. This paper assumes that the relationship between wave steepness and wave age changes with the variety of dimensionless fetch. Based on the relationship proposed by Hou and Wen (1990), a new relationship in the course of wind wave growth is revealed. Comparisons between the present study and other previous relationships show that this new relationship explains better the observations than the other existing relationships.In the case of small fetch, wave age value increases more quickly than other models while it is in opposition to that in the case of large fetch. The result in present paper can clearly reflect the whole course of wind wave growth, it is an improvement for traditional results. 相似文献
2.
The Antarctic circumpolar wave （ACW） has become a focus of the air-sea coupled Southern Ocean study since 1996, when it was discovered as an air-sea coupled interannual signal propagating eastward in the region of the Antarctic Circumpolar Current （ACC）. In order to analyze the mechanism of discontinuity along the latitudinal propagation, a new idea that ACW is a system with a traveling wave in the Southern Pacific and Atlantic Ocean and with a concurrent standing wave in the southern Indian Ocean is proposed in this paper. Based on the ideal wave principle, the average wave parameters of ACW is achieved using a non-linear approximation method, by which we find that the standing part and the traveling part possess similar radius frequency, proving their belonging to an integral system. We also give the latitudinal distribution of wave speed with which we could tell the reason for steady propagation during the same period. The spatial distribution of the propagation reveals complex process with variant spatial and temporal scales--The ENSO scale oscillation greatly impacts on the traveling process, while the result at the south of Australia indicates little connection between the Indian Ocean and the Pacific, which may be blocked by the vibration at the west of the Pacific. The advective effect of ACC on the propagation process should be examined clearly through dynamical method. 相似文献
3.
《中国海洋湖沼学报》2016,(5)
Directional wave spectra and integrated wave parameters can be derived from X-band radar sea surface images.A vessel on the sea surface has a significant influence on wave parameter inversions that can be seen as intensive backscatter speckles in X-band wave monitoring radar sea surface images.A novel algorithm to eliminate the interference of vessels in ocean wave height inversions from X-band wave monitoring radar is proposed.This algorithm is based on the characteristics of the interference.The principal components(PCs) of a sea surface image sequence are extracted using empirical orthogonal function(EOF)analysis.The standard deviation of the PCs is then used to identify vessel interference within the image sequence.To mitigate the interference,a suppression method based on a frequency domain geometric model is applied.The algorithm framework has been applied to OSMAR-X,a wave monitoring system developed by Wuhan University,based on nautical X-band radar.Several sea surface images captured on vessels by OSMAR-X are processed using the method proposed in this paper.Inversion schemes are validated by comparisons with data from in situ wave buoys.The root-mean-square error between the significant wave heights(SWH) retrieved from original interference radar images and those measured by the buoy is reduced by 0.25 m.The determinations of surface gravity wave parameters,in particular SWH,confirm the applicability of the proposed method. 相似文献
4.
Because of the intrinsic difficulty in determining distributions for wave periods, previous studies on wave period distribution
models have not taken nonlinearity into account and have not performed well in terms of describing and statistically analyzing
the probability density distribution of ocean waves. In this study, a statistical model of random waves is developed using
Stokes wave theory of water wave dynamics. In addition, a new nonlinear probability distribution function for the wave period
is presented with the parameters of spectral density width and nonlinear wave steepness, which is more reasonable as a physical
mechanism. The magnitude of wave steepness determines the intensity of the nonlinear effect, while the spectral width only
changes the energy distribution. The wave steepness is found to be an important parameter in terms of not only dynamics but
also statistics. The value of wave steepness reflects the degree that the wave period distribution skews from the Cauchy distribution,
and it also describes the variation in the distribution function, which resembles that of the wave surface elevation distribution
and wave height distribution. We found that the distribution curves skew leftward and upward as the wave steepness increases.
The wave period observations for the SZFII-1 buoy, made off the coast of Weihai (37°27.6′ N, 122°15.1′ E), China, are used
to verify the new distribution. The coefficient of the correlation between the new distribution and the buoy data at different
spectral widths (ν=0.3−0.5) is within the range of 0.968 6 to 0.991 7. In addition, the Longuet-Higgins (1975) and Sun (1988)
distributions and the new distribution presented in this work are compared. The validations and comparisons indicate that
the new nonlinear probability density distribution fits the buoy measurements better than the Longuet-Higgins and Sun distributions
do. We believe that adoption of the new wave period distribution would improve traditional statistical wave theory. 相似文献
5.
In this paper, function characteristics of dispersion of ocean wave in finite depth water were analyzed systematically. The functional form of the fitting function is reasonably proposed, in which the parameters are optimally determined by the least square method （LSM）. For infinitely deep and extremely shallow water,the fitting function fits strictly the dispersion to be fitted. A new technique is presented in application of LSM.An empirical formula with maximum error of less than 0.5% for computing wavelength in finite depth water is presented for practical applications. 相似文献
6.
The effect of ocean wave breaking as a non-Bragg mechanism on backscattering cross-section and modulation transfer functions （MTF） of radar was investigated based on Bragg resonance theory and parametric method. The result showed that the additional effect of wave breaking on backscattering cross-section is not more than 20% except for the small incident angle of VV polarized electromagnetic （e.m.） wave but is significant for HH polarized e.m. wave. Breaking waves lead to increase in the modulus of tilt modulation MTF and the larger the wind speed, the faster the increase. For large incident angle, the modulus of tilt modulation MTF with wave breaking decreases quickly with incident angle for HH polarization and approach to that without wave breaking for VV polarization. The hydrodynamic MTF increases 30%-60% when considering wave breaking and the increase is larger for HH polarization than for VV polarization. 相似文献
7.
The effect of ocean wave breaking as a non-Bragg mechanism on backscattering cross-section and modulation transfer functions (MTF) of radar was investigated based on Bragg resonance theory and parametric method. The result showed that the additional effect of wave breaking on backscattering cross-section is not more than 20% except for the small incident angle of VV polarized electromagnetic (e.m.) wave but is significant for HH polarized e.m. wave. Breaking waves lead to increase in the modulus of tilt modulation MTF and the larger the wind speed, the faster the increase. For large incident angle, the modulus of tilt modulation MTF with wave breaking decreases quickly with incident angle for HH polarization and approach to that without wave breaking for VV polarization. The hydrodynamic MTF increases 30%-60% when considering wave breaking and the increase is larger for HH polarization than for VV polarization. 相似文献
8.
lareODUcrI0NThephenomenonofbreakingwavesintheoasnoocurswheneveramomentahiyhighcrestmecheSanunstablecondition.It0ccursintendtimhy,andtheoccurrencefre-qUencydePendsonthescastate.ManystudAshaddricaniedoutontheoccurmcefre-qUencyofbrmkingwavesindeepweter.0chiandTsai(l983),LongueHiggins(l975)andVanD0mandPamn(l975)nadstheptalictonofbrmkingwavesoccurrenceindeePwater,usingabaskingcriterionforindividualwavesbasedonthewavesmpness.ThecriterioncanbeexpmeedintennSofthewaVehdghtHandperiodTasH>PgT'(… 相似文献
9.
Linear wave theory and Longuet-Higgins and Steward's (1964) group-induced second-order longweve (GSLW) theory ware used in this study on the grouping effect on wave forces acting on a verticalbreakwater. The calculated variance of total wave pressure on the vertical breakwater was closer tothe measured value if the wave grouping effect was considered. 相似文献
10.
A WEAKLY NONLINEAR WATER WAVE MODEL TAKING INTO ACCOUNT DISPERSION OF WAVE PHASE VELOCITY 总被引：1，自引：0，他引：1
This paper presents a weakly nonlinear water wave model using a mild slope equation and a new explicit formulation which takes into account dispersion of wave phase velocity, approximates Hedges‘ (1987) nonlinear dispersion relationship, and accords well with the original empirical formula. Comparison of the calculating results with those obtained from the experimental data and those obtained from linear wave theory showed that the present water wave model considering the dispersion of phase ve-locity is rational and in good agreement with experiment data. 相似文献
11.
《中国海洋湖沼学报》2019,(6)
The effect of the drag coefficient on a typhoon wave model is investigated. Drag coefficients for Pingtan Island are derived from the progress of nine typhoons using COARE 3.0 software. The wind parameters are obtained using the Weather Research and Forecasting model. The simulation of wind agrees well with observations. Typhoon wave fields are then simulated using the third-generation wave model SWAN. The wave model includes exponential and linear growths of the wind input, which determine the wave-growth mode. A triple triangular mesh is adopted with spatial resolution as fine as 100 m nearshore. The SWAN model performs better when using the new drag coefficient rather than the original coefficient. 相似文献
12.
The objective of this study is to experimentally investigate the effectiveness of Tuned Liquid Dampers (TLDs) for suppressing the dynamic response of a platform structure subjected to wave loading and to explore the applicability of TLDs for suppressing the structural vibration of fixed offshore platforms. The experimental model is scaled according to a full size platform by matching its dynamic properties. Rectangular and circular TLDs of various sizes and water depths are examined.The experiments were performed in a 2-D wave flume. The effectiveness of TLDs is evaluated based on their response reduction. By observing the performance and the behavior of TLDs through laboratory experiments, the effects of a number of parameters including container shape, container size, number of dampers, frequency ratio, mass ratio, and incident wave characteristics are investigated. 相似文献
13.
基于波动方程预测相减的表面多次波压制方法,能较好压制地下复杂介质产生的多次波,但是计算成本较高。基于滤波方法压制多次波计算效率较高,对一次波和多次波存在较大时差的地震数据有明显的压制效果,但是对来自复杂介质的地震数据较难得到良好的压制效果。将波动方程法和滤波法结合,提出一种基于抛物Radon变换和波动方程的多次波压制方法。首先应用表面多次波形成机理预测多次波,利用对应的预测多次波的地震记录和初始地震记录,在抛物Radon域设计自适应滤波函数,通过准确滤波得到多次波在抛物Radon域的能量;然后通过反变换得到多次波,从原始地震记录中减去多次波,得到压制多次波后的结果。水平层状模型及SMAART模型测试结果表明,该方法结合两种方法的优点,能够准确、高效压制来自地下复杂介质产生的表面多次波。 相似文献
14.
To understand the processes and energy dissipation performance caused by turbulence during the wave run-up over a stepped revetment, hydraulic model tests with steady flow conditions are conducted and correlated with unsteady flow conditions of the wave run-up within a short time frame. Under irregular waves, the run-up reduction over a stepped revetment is dependent on the Iribarren number and decreases for decreasing Iribarren numbers. Velocity gradients are found to be similar in a steady and unsteady flow regime near the pseudo-bottom. 相似文献
15.
Zhifeng Wang Liangming Zhou Sheng Dong Lunyu Wu Zhanbin Li Lin Mou Aifang Wang 《中国海洋大学学报(英文版)》2014,13(6):893-900
Wave simulation was conducted for the period 1976 to 2005 in the South China Sea (SCS) using the wave model, WAVEWATCH-III. Wave characteristics and engineering environment were studied in the region. The wind input data are from the objective reanalysis wind datasets, which assimilate meteorological data from several sources. Comparisons of significant wave heights between simulation and TOPEX/Poseidon altimeter and buoy data show a good agreement in general. By statistical analysis, the wave characteristics, such as significant wave heights, dominant wave directions, and their seasonal variations, were discussed. The largest significant wave heights are found in winter and the smallest in spring. The annual mean dominant wave direction is northeast (NE) along the southwest (SW)-NE axis, east northeast in the northwest (NW) part of SCS, and north northeast in the southeast (SE) part of SCS. The joint distributions of wave heights and wave periods (directions) were studied. The results show a single peak pattern for joint significant wave heights and periods, and a double peak pattern for joint significant wave heights and mean directions. Furthermore, the main wave extreme parameters and directional extreme values, particularly for the 100-year return period, were also investigated. The main extreme values of significant wave heights are larger in the northern part of SCS than in the southern part, with the maximum value occurring to the southeast of Hainan Island. The direction of large directional extreme H s values is focus in E in the northern and middle sea areas of SCS, while the direction of those is focus in N in the southeast sea areas of SCS. 相似文献
16.
ImooUcrIONAtfrequendesseveraltirathatofthespeCtralpcak,thewaveelevationhigherordercomPonentS'contributionstothewavespatrumaremoresignificantthanthosefromthelinearcomPonentS.Tick(l959)firstproposedandevaluatedtheserendxidespodrumofunidindionalrandomwaves.TheexpnaionderivedbyDingPingxingetal.(l994)forthesecondxirderspeCtmmisanimProvernentofTick's.TickandDingPingxingetal.didnotaanuntforthirdxirderperturbations,althoughthethirdxirdersolutionefhaonthequadraticspeCtrumisofthesameorderofmagnit… 相似文献
17.
Studying the relationship between wave steepness and wave age is important for describing wind wave growth with energy balance equation of significant waves. After invoking the dispersion rela- tion of surface gravity wave in deep water, a new relationship between wave steepness and wave age is revealed based on the “3/2-power law” (Toba, 1972), in which wave steepness is a function of wave age with a drag coefficient as a parameter. With a given wave age, a larger drag coefficient would lead to larger wave steepness. This could be interpreted as the result of interaction between wind and waves. Comparing with previous relationships, the newly proposed one is more consistent with observational data in field and laboratory. 相似文献
18.
In considering the vertical heat transport problems in the upper ocean, the flat upper boundary approximation for the free
surface and the horizontal homogenous hypothesis are usually applied. However, due to the existence of the wave motion, the
application of this approximation may result in some errors to the solar irradiation since it decays quickly in respect to
the actual thickness of the water layer below the surface; on the other hand, due to the fluctuation of the water layer depth,
it is improper to neglect the effects of the horizontal advection and turbulent diffusion since they also contribute to the
vertical heat transport. A new model is constructed in this study to reflect these effects. The corresponding numerical simulations
show that the wave motion may remarkably accelerate the vertical heat transferring process and the variation of the temperature
in the wave affected layer appears in an oscillating manner.
Supported by the National High Technology Research and Development Program of China (863 Program, No. 2006AA09A309); China
Postdoctoral Science Foundation (No. 20070411111) and the Fund of Shandong Province for the Excellent Post-Doctors (No. 200603056) 相似文献
19.
The paper introduces a new approach to estimating the T-year return-period wave height (TRPW), i.e. the wave height expected to occur in T-year, from two sets of observed extreme data and on the basis of the maximum entropy principle. The main points of the approach are as follows. 1) A maximum entropy probability density function (PDF) for the extreme wave height H is derived from a Euler equation subject to some necessary and rational constraints. 2) The parameters in the function are expressed in terms of the mth moment of H. 3) This PDF is convenient to theoretical and practical applications as it is simple and its four parameters are easy to be determined from observed extreme data. An example is given for estimating the TRPW in 50 and 100 years by the present approach and by some currently used methods using observed data at two hydrographic stations.The comparison of the estimated results shows that the present approach is quite similar to the Pearson-Ⅲ and Gumbel methods. 相似文献
20.
楼菁 《中国海洋湖沼学报》1994,12(4):361-371
A numerical model based on the mild-slope equation of water wave propagation over complicated bathymetry,taking into account the combined effects of refraction,diffraction and dissipation due to wavebreaking is presented.Wave breaking is simulated by modifying the wave height probability density func-tion and the wave energy dissipation mechanism is parameterized according to that of the hydraulic jumpformulation.Solutions of the wave height,phase function,and the wave direction at every grid point areobtained by finite difference approximation of the governing equations,using Gauss-Seidel Iterative Method(GSIM)row by row.Its computational convenience allows it to be applied to large coast regions tostudy the wave transformation problem.Several case studies have been made and the results compare verywell with the experiment data and other model solutions.The capability and utility of the model forreal coast areas are illustrated by application to a shallow bay of northeast Australia. 相似文献