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1.
Wind-generated waves in Hurricane Juan 总被引：3，自引：0，他引：3
We present numerical simulations of the ocean surface waves generated by hurricane Juan in 2003 as it reached its mature stage (travelling from deep waters off Bermuda to Nova Scotia and making landfall near Halifax) using SWAN (v.40.31) nested within WAVEWATCH-III (v.2.22; denoted WW3) wave models, implemented on multiple-nested domains. As for all storm-wave simulations, spectral wave development is highly dependent on accurate simulations of storm winds during its life cycle. Due to Juan’s rapid translation speed (accelerating from 2.28 m s−1 on 27 September, 1200 UTC to 20 m s−1 on 29 September, 1200 UTC), an interpolation method is developed to blend observed hurricane winds with numerical weather prediction (NWP) model winds accurately. Wave model results are compared to in situ surface buoys and ADCP wave data along Juan’s track. At landfall, Juan’s maximum waves are mainly swell-dominated and peak waves lag the occurrence of the maximum winds. We explore the influence of surface waves on the wind and show that the accuracy of the wave simulation is enhanced by introducing swell and Stokes drift feedback mechanisms to modify the winds, and by limiting the peak drag coefficient under high wind conditions, in accordance with recent theoretical and experimental results. 相似文献
2.
A new empirical formula for the aerodynamic roughness of water surface waves has been derived from laboratory experimental results using dimensional analysis. The formula has different forms according to wind speed: at moderate wind speeds the formula is a function of the friction velocity of wind, the surface tension, the water density, the kinematic viscosity of water and the acceleration of gravity; at strong winds the formula is expressed by the Charnock relation. The aerodynamic roughness does not depend on such wave state parameters as the spectral peak frequency or the steepness of waves, unlike almost all parameterizations that have been proposed to date. The drag coefficient at moderate winds depends on the surface tension of water and the water temperature through the temperature dependence of the kinematic viscosity of water. 相似文献
3.
根据１９８３－１９８９年南麂海洋站在台风影响过程中的实测风和浪资料，分析了该海域的波浪特征。结果表明，这个海域的台风波浪通常是混合浪，在台风影响过程中出现的最大值波高，既有较大波陡的风浪，也有波陡较小的清浪；各向波高的均值变化不大，各向最大波高却有较大幅度的差距；本区的台风浪以４级波高占优，风浪以ＮＮＥ向、涌浪以Ｅ向为常浪向；波高为４级的风浪和涌浪，其周期分别在４．０－４．９Ｓ和７．０－７．９Ｓ之 相似文献
4.
Statistical study on the local equilibrium between wind and wind waves by using data from ocean data buoy stations 总被引：6，自引：0，他引：6
The local equilibrium between the wind and wind waves, which is defined by a range of the coefficient of the 3/2-power law between the non-dimensional significant wave height and period, is statistically investigated by using wind and wave data obtained at four ocean data buoy stations in the seas near Japan. The friction velocity is calculated from the wind speed measured at one height together with the significant wave period by using formulas of the wave dependent drag coefficient proposed by Tobaet al. (1990). The data for small waves or for weak winds indicate that the waves do not satisfy the criterion for the local equilibrium, because they may be affected by changing winds or remotely generated swells. In the seas near Japan, the data which satisfy the local equilibrium are about 6% through a year. Otherwise swells are dominant in most situations. Changing winds also cause deviations from the local equilibrium. The degree of satisfaction of the local equilibrium can be classified by ranges of the significant wave height. As the significant wave height exceeds 4 m, the local equilibrium is more frequently satisfied. 相似文献
5.
风浪和海洋飞沫对海表面拖曳系数和风廓线的影响 总被引：2，自引：1，他引：1
基于埃克曼理论,本文将波致应力和飞沫应力引入到海-气边界层的界面应力中,来研究海表面风浪和海洋飞沫对海-气边界层动量交换的影响,并得到修改后的埃克曼模型的理论解。波致应力是由风浪谱和波增长函数估计,并得到在中低风速下,波致应力、飞沫应力与湍流应力相比,对海表面拖曳系数和风廓线的影响非常小。当风速高于25米/秒时,海洋飞沫通过飞沫应力对海-气界面应力的作用远高于波致应力,以至于波致应力可以忽略。海表面拖曳系数在高风速下,随着风速的增大而减小。通过采用风浪谱的不同波龄,得到海洋飞沫的产生会导致海-气边界层风速的增加。最后,理论解与现场的观察数据进行了对比。对比后的数据表明,在中高风速下,飞沫对海-气边界层的影响远大于表面风浪。 相似文献
6.
Wind speed scaling and the drag coefficient 总被引：2，自引：0，他引：2
[1]Banner M L, Chen W, Walsh E J, et al. 相似文献
7.
-Drift current induced by wind and waves is investigated with phase-averaged Navier-Stokes equation in which the Reynolds stress is closed by k-ε model. The governing equations are solved by the finite volume method in a system of nonorthogonal coordinates which is fitted to the phase-averaged wave surface. The predicted drift current is fairly reasonable and the drag coefficient of sea-surface predicted with the newly developed interface conditions shows good agreement with previous measurements when breaking waves do not exist. 相似文献
8.
Paul A. Hwang 《Journal of Oceanography》2004,60(5):835-841
Surface waves are the roughness element of the ocean surface, the air-sea interaction processes are influenced by the wave
conditions. The dynamic influence of surface waves decays exponentially with distance from the air-water interface. The relevant
length scale characterizing the decay rate is the wavelength. The parameterization of drag coefficient and surface roughness
can be significantly improved by using wavelength as the reference length scale of atmospheric measurements. The wavelength
scaling of drag coefficient and dynamic roughness also receives support from theoretical studies of wind and wave coupling. 相似文献
9.
Naoto Ebuchi 《Journal of Oceanography》1999,55(5):575-584
By using wind vector fields observed by the NASA Scatterometer (NSCAT) and significant wave heights observed by the TOPEX/POSEIDON and European Remote Sensing Satellite-2 (ERS-2) altimeters, one-dimensional fetch growth of wind waves has been investigated under conditions of strong wind and high waves caused by the East Asian winter monsoon in the Sea of Japan. The evolution of fetch-limited wind waves can be observed by the altimeters along their ground tracks. The fetch is estimated by using vector wind fields observed by NSCAT. The derived growth characteristics of wind waves are compared with empirical relationships between the non-dimensional fetch and significant wave height proposed by previous studies. Good agreement is discernible with Toba's fetch graph formula normalized by the friction velocity, while Wilson's well-known formula normalized by the wind speed at a height of 10 m tends to underestimate the wave height under such severe conditions of high wind and very long fetch. This discrepancy is explained by the wind-speed dependence of the drag coefficient. A simple correction to Wilson's formula for the high wind conditions is proposed and compared with the observed data. 相似文献
10.
SWAN模型中不同风拖曳力系数对风浪模拟的影响 总被引：1，自引：1，他引：0
本文以荷兰哈灵水道海域为实验区域,通过敏感性实验,研究了在14 m/s、31.5 m/s和50 m/s（分别代表一般大风、强热带风暴和强台风的极端条件）定常风速下SWAN模型中不同风拖曳力系数对风浪模拟的影响程度。结果表明,对于近岸浅水区域（水深小于20 m）,风拖曳力系数计算方案的选择对有效波高影响较小,而且当风速增加到一定程度后,波浪破碎成为影响波高值的主要因素;对于深水区域（水深大于30 m）,一般大风条件下风拖曳力系数计算方案的选择对有效波高影响仍然较小,随着风速的继续增大,风拖曳力系数计算方案的选择对有效波高的影响逐渐显著。对于平均周期,风拖曳力系数计算方案的选择和风速的改变对其影响均较小,而由水深变浅导致的波浪破碎对其影响较为显著。根据敏感性实验结果,本文对SWAN模型中风拖曳力系数计算方案的选择做出如下建议:计算近岸浅水区域风浪场或深水区域一般大风条件风浪场时,其风拖曳力系数可以直接采用模型默认选项;而对于深水区域更大风速条件,可首先采用模型默认选项试算,然后结合当地海域实测波浪资料进行修正。 相似文献
11.
Surface waves are the roughness element of the ocean surface. The parameterization of the drag coefficient of the ocean surface is simplified by referencing to wind speed at an elevation proportional to the characteristic wavelength. The dynamic roughness is analytically related to the drag coefficient. Under the assumption of fetch limited wave growth condition, various empirical functions of the dynamic roughness can be converted to equivalent expressions for comparison. For datasets covering a wide range of the dimensionless frequency (inverse wave age), it is important to account for the variable rate of wave development at different wave ages. As a result, the dependence of the Charnock parameter on wave age is nonmonotonic. Finally, the analysis presented here suggests that the significant wave steepness is a sensitive property of the ocean surface and a single variable normalization of the dynamic roughness using a wavelength or wave height parameter actually produces more robust functions than bi-variable normalizations using wave height and wave slope. 相似文献
12.
Analytically Derived Wind Wave Growth Relations 总被引：3，自引：1，他引：3
By the use of the 3/2 power law presented by Toba combined with the significant wave energy balance equation for wind wave, wind wave growth at a limited fetch is analytically investigated. The new wind wave growth relations (WWGRs) are analytically derived with shehering coefficient and wind drag coefficient as parameters. The geometrical average of observational values of shehering coefficient and the arithmetic average of observational values of wind drag coefficient are applied to detennine the new WWGRs. Comparisons with existing empirical WWGRs are made. 相似文献
13.
Amal C. Phadke Christopher D. Martino Kwok Fai Cheung Samuel H. Houston 《Ocean Engineering》2003,30(4):5039-578
This paper compares three commonly used parametric models of tropical cyclone winds and evaluates their application in the wave model WAM. The parametric models provide surface wind fields based on best tracks of tropical cyclones and WAM simulates wave growth based on the wind energy input. The model package is applied to hindcast the wind and wave conditions of Hurricane Iniki, which directly hit the Hawaiian Island of Kauai in 1992. The parametric wind fields are evaluated against buoy and aircraft measurements made during the storm. A sensitivity analysis determines the spatial and spectral resolution needed to model the wave field of Hurricane Iniki. Comparisons of the modeled waves with buoy measurements indicate good agreement within the core of the storm and demonstrate the capability of the model package as a forecasting tool for emergency management. 相似文献
14.
A coupled wave–tide–surge model has been established in this study in order to investigate the effect of tides, storm surges, and wind waves interactions during a winter monsoon on November 1983 in the Yellow Sea. The coupled model is based on the synchronous dynamic coupling of a third-generation wave model, WAM-Cycle 4, and the two-dimensional tide–surge model. The surface stress generated by interactions between wind and waves is calculated using the WAM-Cycle 4 directly based on an analytical approximation of the results obtained from the quasi-linear theory of wave generation. The changes of bottom friction factor generated by waves and current interactions are calculated by using simplified bottom boundary layer model. The model simulations showed that bottom velocity and effective bottom drag coefficient induced by combination of wave and current were increased in shallow waters of up to 50 m in the Yellow Sea during the wintertime strong storm conditions. 相似文献
15.
基于选定风浪方向谱的海浪模拟方法(英文) 总被引：1，自引：0，他引：1
简要回顾当前第三代海浪模式中的困难。为避开这些困难,作者提出一种新的海浪模拟方法,其中特定定义的风浪组成波依常风下随时间成长的方向谱计算,而涌浪组成波藉考虑涡动黏性和底摩擦加以计算。并进行了常风场和变风场下系统的数值试验。在常风速情形中,模拟结果能精确地化为建立模拟所根据的谱和风浪成长关系。计算显示出台风中心附近浪场的极端复杂的谱结构。当风速骤然降低时,模拟的波高减小与观测符合。在风向逐渐或骤然改变情形下,计算的时间响应尺度与海上观测符合,而且演化中的二维谱结构得到良好刻画。对于涌浪在无风下的传播,模拟结果合理,包括波参量及谱结构的变化。后报得到的波高、周期和海上资料符合。与第三代模式相比,文中提出的方法较易改进,需用的计算机时间显著减少。最后讨论采用一个已知谱来建立谱形式的海浪预报模型的合理性以及有关的问题。 相似文献
16.
海气动量通量研究综述 总被引：1，自引：0，他引：1
海气界面动量通量也称为风应力,是海流和表面海浪的主要驱动力,是海洋从大气获得动量的重要途径。因此,合理可靠的海洋表面风应力的参数化对于海洋、大气和波浪以及气候模式的准确预报都具有非常重要的科学意义和实用价值。对风应力拖曳系数的参数化是风应力参数化的主要内容。近来的观测发现,风应力拖曳系数随着风速的增加出现了先增后减的趋势,同时还与海面的波浪状态以及海流有关。基于观测或理论分析,目前已经得到了一系列的风应力拖曳系数计算方法或公式,有的考虑了海浪的作用,有的没有,但这些方案大都是适合中低风速,在高风速下的适用性还有待检验。本文回顾了目前在海气动量通量观测和参数化方面的研究进展,并建议应增加高风速下风速、海流以及海浪等的同步观测,以进一步完善风应力参数化方案。 相似文献
17.
A coupled wave–tide–surge model has been developed in this study in order to investigate the effect of the interactions among tides, storm surges, and wind waves. The coupled model is based on the synchronous dynamic coupling of a third-generation wave model, WAM cycle 4, and the two-dimensional tide–surge model. The surface stress, which is generated by interactions between wind and wave, is calculated by using the WAM model directly based on an analytical approximation of the results using the quasi-linear theory of wave generation. The changes in bottom friction are created by the interactions between waves and currents and calculated by using simplified bottom boundary layer model. In consequence, the combined wave–current-induced bottom velocity and effective bottom drag coefficient were increased in the shallow waters during the strong storm conditions. 相似文献
18.
A review of the climatological characteristics of landfalling Gulf hurricanes for wind, wave, and surge hazard estimation 总被引：1，自引：0，他引：1
The climatological characteristics of landfalling Gulf of Mexico hurricanes are presented, focusing on the basic parameters needed for accurately determining the structure and intensity of hurricanes for ocean response models. These include the maximum sustained wind, radius of maximum winds, the Holland-B parameter, the peripheral or far-field pressure, the surface roughness and coefficient of drag, and the central pressure for historical hurricanes in the Gulf.Despite evidence of a slight increase in the annual number of named storms over the past 50 years, presently there is no statistically significant trend in tropical storms, hurricanes, or major hurricanes in the Gulf of Mexico. In addition, the long-term variability of tropical cyclones in the Gulf reflects the observed variability in the Atlantic basin as a whole. Analyses of hurricane winds from multiple sources suggest the presence of a bias toward overestimating the strength of winds in the HURDAT dataset from 7% to 15%. Results presented comparing HURDAT with other sources also show an overestimation of intensity at landfall, with an estimated bias of ~10%.Finally, a review of recent studies has shown that hurricane frequencies and intensities appear to vary on a much more localized scale than previously believed. This exacerbates the sampling problem for accurate characterization of hurricane parameters for design and operational applications. 相似文献
19.
The paper concentrates on the evolution of a spectrum of short wind waves (SW) along the profile of a long surface wave (LW).
Short wave spectral variations are considered in the relaxation approximation. The SW spectrum is modulated by the orbital
velocities of long waves and by the variations of wind stress along the LW profile. The latter effect occurs due to wind flux
perturbations induced by both the long wave proper and variations of the sea surface roughness induced by the SW modulations.
To describe this effect, a feedback mechanism is introduces—the growth of energy of short waves results in the larger roughness
of the sea surface, thereby contributing to the local wind stress, which facilitates, in turn, the growth of short waves.
With moderate and strong winds being involved, this effect (aerodynamic feedback) is shown to be dominant in the short wave
spectrum modulation. The mechanism becomes more efficient with intensification of the wind and decreasing of the long waves'
frequency. Results of model calculations are in agreement with the known experimental data.
Translated by Vladimir A. Puchkin. 相似文献
20.
The climatology of the troposphere–stratosphere–mesosphere model of the Institute for Numerical Mathematics (INM) with the uppermost level at 0.003 hPa is presented. This model is vertically extended from the upper level of 10 hPa for the earlier version, and a drag parameterization due to internal gravity waves (GW) is included. The model describes the main features of the mesospheric circulation: decreasing and reversion of westerly and easterly winds, equatorward shift of the westerly wind maximum with height and reversal of the meridional temperature gradient in the upper mesosphere. The model underestimates to some extent the amplitude of wave number 1 for stationary waves in the winter hemisphere. The same holds for the internal low‐frequency variability in the winter stratosphere. The sensitivity of the model climate is studied with respect to the inclusion of orographic gravity wave drag and the variation of the source height of internal gravity waves. 相似文献