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1.
The relationship between the RMS amplitudes of the wind wave spectral components and the wind speed has been studied at ten frequencies in the band of 0.65–23 Hz. To measure the parameters of the high-frequenci waves, a resistance elevation wave gauge was operated, which was deployed in the Black See on an oceanographic platform near Katsively. The correlation between the wave amplitudes and the wind velocity at high frequencies of 5–23 Hz, corresponding to gravitation-capillary ripples, was found to reach a value of 0.8. At lower frequencies of 0.65–4.3 Hz, corresponding to short gravity waves, it dropped to 0.5–0.7. The response of spectral components to the wind speed variations in the gravity-capillary range is higher than in the range of short gravity waves. The results obtained differ from Phillips' idea about a saturated range for the frequency form of the spectrum of high-frequency gravity waves, since a linear dependence of the spectral amplitudes on the wind speed is established at a wind of force 1–8.Translated by Mikhail M. Trufanov. 相似文献
2.
Based on observations from buoys, it is found that the wave age is well correlated with the nondimensional wave height, and this correlation is best described by a 3/5-power law. This similarity law is valid in the cases of wind waves as well as swells under natural sea states. On the basis of the 3/5-power law combined with the well-known 3/2-power law, it is shown that the wave-induced wind stress increases rapidly with wave age, indicating that the traditional observations or analytic techniques have only given the turbulent Reynolds stress induced by short wind waves, but excluded the long-wave-induced wind stress. The latter constitutes a small fraction to the total wind stress when the wave age is smaller than 1.0. The increase of sea-surface roughness with wave age can be attributed to wave breaking. 相似文献
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4.
Beng-Chun Lee Li-Chung Wu Dong-Jiing Doong Chia Chuen Kao 《Marine Geophysical Researches》2007,28(3):183-190
We here investigate the frequency and intensity of oscillations in oceanographic data within intraseasonal time scales using
spectral analysis of surface wind and wave time-series data collected at off-island weather stations or moored buoys around
Taiwan. Data from marine weather stations were used to trace atmospheric conditions, while we used buoy data to examine sea
states. The spectra and wavelet scalogram of the wind fields revealed oscillations with a period of around 20–33 days, and
the energy density of the wind field at the off-island stations was stronger than that at the data buoy stations. However,
the wavelet scalogram of the wave height measured at the buoy stations was stronger than its associated wind field. This long-period
oscillation is consistent with the wavelet scalogram of the wind field calculated from the off-island weather stations. About
20–33 day oscillations exist within intraseasonal variations, which are closely linked to the atmospheric environment and
to wind and ocean wave fields. Oscillations with a period of 5–10 days are a pronounced feature over northeastern Taiwan waters
during the winter season and can be interpreted as the wave pattern following synoptic weather systems. 相似文献
5.
Data on the temporal variability of sea wave spectral components in the frequency range 1–8 Hz, collected by a drifting vessel in the Pacific ocean (wind speed 1–10 m/s), are discussed in this paper. For the frequency range 3–6 Hz (wind speed 5–8 m/s), a weak variability of the ripples is observed, synchronous with long waves; in the remaining part of the spectral range studied the fluctuations are fortuitous. It is concluded that the wind plays a crucial role in forming the ripples' fluctuation characteristics in the high-frequency part of the spectrum.Translated by Vladimir A. Puchkin. 相似文献
6.
The results of radiometric remote simultaneous field measurements of the temperature and radiation capacity of the upper layer of the sea-surface temperature film 0.2 mm thick are presented. The measurements were conducted in the presence of wind waves and were characterized by an increased accuracy, which was achieved owing to the use of measurements of the intensity of radio radiation from the surface illuminated by radiation of a specified varying power. In our experiment, this illumination was provided by the radio radiation of the atmosphere, whose radiance temperature varies significantly, depending on the frequency at the slope of the absorption band of molecular oxygen (52.5–56 GHz). As a result, the radiation capacity and temperature of the skin layer were determined from the correlation dependence between the radiance temperatures of the surface and atmosphere measured by a radiometer-spectrometer in a number of channels separated in frequency. The radiance temperatures of the sea and atmosphere were measured at four frequencies of the 5-mm spectral range (53–55 GHz) on a vertical polarization. For absolute measurements, a calibration method was developed on the basis of a blackbody disk and two reflecting mirrors with the same solid angles. The measured values of the radiation capacity are variable and substantially smaller than the theoretical values determined by the models accepted for the permittivity of water and sea roughness. A possible cause of this can be the change of the permittivity of water in a thin surface layer of the temperature film (0.2 mm) due to the concentration of gases dissolved in water and surface-active substances within this layer. 相似文献
7.
G. S. Golitsyn 《Izvestiya Atmospheric and Oceanic Physics》2010,46(1):6-13
The problems of wind-induced waves on the sea surface are considered. To this end, the empirical fetch laws that determine
variations in the basic periods and heights of waves in relation to their fetch are used. The relation between the fetch and
the physical time is found, as are the dependences of the basic characteristics of waves on the time of wind forcing. It is
found that about 5% of wind energy dissipated in the near-water air layer contributes to the growth of wave heights, i.e.
wave energy, although this quantity depends on the age of waves and the exponent in the fetch laws. With consideration for
estimates of the probability distribution functions for the wind over the world ocean [11], it is found that the rate of wind-energy
dissipation in the near-water air layer is on the order of 1 W/m2. The calculations of wind waves [19] for the world ocean for 2007 have made it possible to assess the mean characteristics
of the cycle of wave development and their seasonal variations. An analysis of these calculations [19] shows that about 20%
of wind energy is transferred to the water surface. The remaining amount (80%) of wind energy is spent on the generation of
turbulence in the near-water air layer. About 2%, i.e., one tenth of the energy transferred to water, is spent on turbulence
generation due to the instability of the vertical velocity profile of the Stokes drift current and on energy dissipation in
the surf zones. Of the remaining 18%, 5% is spent directly on wave growth and 13% is spent on the generation of turbulence
during wave breaking and on a small-scale spectral region. These annually and globally mean estimates have a seasonal cycle
with an amplitude on the order of 20% in absolute values but with a smaller amplitude in relative values. According to [19]
and to the results of this study, the annually mean height of waves is estimated as 2.7 m and their age is estimated as 1.17. 相似文献
8.
Sea-surface acoustic backscattering measurements at moderate to high frequencies were performed in the shallow water of the south Yellow Sea, using omnidirectional spherical sources and omnidirectional hydrophones. Sea-surface backscattering data for frequencies in the 6–25 k Hz range and wind speeds of(3.0±0.5)and(4.5±1.0) m/s were obtained from two adjacent experimental sites, respectively. Computation of sea-surface backscattering strength using bistatic transducer is described. Finally, we calculated sea-surface backscattering strengths at grazing angles in the range of 16°–85°. We find that the measured backscattering strengths agree reasonably well with those predicted by using second order small-roughness perturbation approximation method with "PM" roughness spectrum for all frequencies at grazing angles ranged from 40° to 80°. The backscattering strengths varied slightly at grazing angles of 16°–40°, and were much stronger than roughness scattering. It is speculated that scattering from bubbles dominates the backscattering strengths at high wind speeds and small grazing angles. At the same frequencies and moderate to high grazing angles, the results show that the backscattering strengths at a wind speed of(4.5±1.0) m/s were approximately 5 d B higher than those at a wind speed of(3.0±0.5) m/s. However, the discrepancies of backscattering strength at low grazing angles were more than 10 d B. Furthermore the backscattering strengths exhibited no significant frequency dependence at 3 m/s wind speed. At a wind speed of 4.5 m/s, the scattering strengths increased at low grazing angles but decreased at high grazing angles with increasing grazing angle. 相似文献
9.
We consider the influence of the sea surface state on the backscattered radar cross section and the accuracy of the wind speed retrieval from the scatterometer data. We used a joint set of radars and buoys to determine the type of sea waves. Three types of sea waves were distinguished: developing wind waves, fully developed wind waves, and mixed sea. It is shown that the retrieval error of the near surface wind speed using a one-parameter algorithm is minimal in the case of fully developed wind waves. We compared these data with the results of radio-altimeter data analysis and showed that in both cases underestimation of the retrieval wind speed exists for developing wind waves and overestimation occurs for mixed sea. A variety of swell parameters (length of the dominating wave, swell height, swell age) significantly influence the backscattered radar cross section, leading to a growth in the mean square error of the retrieved wind speed during vertical sounding (radio-altimeter data), and only slightly influence the mean square error of the scatterometer data (medium incidence angles). It is necessary to include the information about the parameters of sea waves in the algorithms and take into account the regional wave properties to increase the accuracy of wind speed retrieval. 相似文献
10.
Hisashi Mitsuyasu 《Journal of Oceanography》2017,73(2):169-180
Wind and wind-generated waves were measured in a wind-wave tank. A clear transition was found in the relation between the wind speed U 10 and the wind friction velocity u * near u * = 0.2 m/s, where U 10 is the wind speed at 10 m height extrapolated from the measured wind profile in a logarithmic layer, and u * = 0.2 m/s corresponds roughly to U 10 = 8 m/s in the present measurement. Quite a similar transition was found in the relation between the spectral density of high frequency wind waves and u *. These results suggest the existence of the critical wind speed for air–sea boundary processes, which was proposed by Munk (J Marine Res 6:203–218, 1947) more than half a century ago. His original idea of the critical wind speed was based on the discontinuities in such phenomena as white caps, wind stress, and evaporation, which commonly appear at a wind speed near 7 m/s. On the basis of the results of our present study and those of earlier studies, we discuss the phenomena which are relevant to the critical wind speed for the air–sea boundary processes. The conclusion is that the critical wind speed exists and it is attributed to the start of wave breaking rather than the Kelvin–Helmholtz instability, but the air–sea boundary processes are not discontinuous at a particular wind speed; because of the stochastic nature of breaking waves, the changes occur over a range of wind speeds. Detailed discussions are presented on the dynamical processes associated with the critical wind speed such as wind-induced change of sea surface roughness and high frequency wave spectrum. Future studies are required, however, to clarify the dynamical processes quantitatively. In particular, there is a need to further examine the gradual change of breaking patterns of wind waves with the increase of wind speed, and the associated change of the structure of the wind over wind waves, such as separation of the airflow at the crest of wind waves, the turbulent stress, and wave-induced stress. Studies on the dynamical structure of the high frequency wave spectrum are also needed. 相似文献
11.
Akira Masuda Tadao Kusaba Kenji Marubayashi Michiyoshi Ishibashi 《Journal of Oceanography》1999,55(2):289-305
The variability of the sea surface wind and wind waves in the coastal area of the Eastern Tsushima Strait was investigated
based on the hourly data from 1990 to 1997 obtained at a station 2 km off Tsuyazaki, Fukuoka. The annual mean wind speed was
4.84 m s−1, with strong northwesterly monsoon in winter and weak southwesterly wind in summer. Significant wave heights and wave periods
showed similar sinusoidal seasonal cycles around their annual means of 0.608 m and 4.77 s, respectively. The seasonal variability
relative to the annual mean is maximum for wave heights, medium for wind speeds, and minimum for wave periods. Significant
wave heights off Tsuyazaki turned out to be bounded by a criterion, which is proportional to the square of the significant
wave period corresponding to a constant steepness, irrespective of the season or the wind speed. For terms shorter than a
month, the significant wave height and the wave period were found to have the same spectral form as the inshore wind velocity:
white for frequencies less than 0.2 day−1 and proportional to the frequency to the −5/3 power for higher frequencies, where the latter corresponds to the inertial
subrange of turbulence. The spectral levels of wave heights and wave periods in that inertial range were also correlated with those of the inshore wind velocity, though the scatter was large.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
12.
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
13.
基于加密的非结构三角网格,以Holland模型风场叠加美国国家环境预报中心（NCEP）海面风场构造的合成风场驱动第三代浅水波浪数值模型（SWAN）对2017年影响闽东海域的“纳沙”和“泰利”台风过程进行数值模拟,并运用浮标站的实测数据对模拟结果进行验证.结果表明,模型计算的风速、有效波高与实测值符合较好,合成风场能较好地模拟台风期间的风速变化过程,SWAN模式能够合理地再现闽东沿海台风浪的时空分布特征.由模拟结果可见：台风“纳沙”中心越过台湾岛进入台湾海峡北部海面,受海峡地形的约束,其波浪场呈NE—SW向椭圆状分布,北部海域的浪高大于南部,闽东沿海遍布大范围的巨浪到狂浪;超强台风“泰利”未登陆闽东,当其台风中心与大陆的距离最近时,海面波浪场分布与台风风场结构一致,台风中心附近海域为14 m以上的怒涛区,巨浪遍布于闽东沿海.研究结果可为闽东沿海台风浪灾害预警和应急管理提供技术支撑和参考依据. 相似文献
14.
The effect of wave age on the wind gust spectrum over wind waves is considered by using the Ochi and Shin [1988. Wind turbulent spectra for design considerations of offshore structures. Proceedings of 20th Offshore Technology Conference, Paper No. 5736, Houston, Texas. pp. 461–467] spectrum together with the wave age dependant Volkov [2001. The dependence on wave age. In: Jones, I.S.F., Toba, Y. (Eds.), Wind Stress Over the Ocean. Cambridge University Press, Cambridge, UK, pp. 206–217] sea surface roughness formula. The wave age independent Charnock [1955. Wind stress on a water surface. Quarterly Journal of Royal Meteorological Society 81, 639–640] sea surface roughness is used as a reference. An example of results demonstrates a clear effect of wave age on the wind gust spectrum. 相似文献
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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
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18.
The small-scale roughness of the sea surface acts as an important link in air-sea interaction processes. Radar and sonar waves are scattered by short surface waves providing the basis for remote sensing methods of the sea surface. At high wind speeds, breaking waves occur. Bubbles penetrate into the water and drastically increase acoustical reverberation, transmission loss and ambient noise. Thus, the development of short waves and wave breaking have to be known to apply radar remote sensing to the surface and to deduce from radar backscatter which sonar conditions prevail. To measure the wind dependence of short waves an experimental device was constructed for use from stationary platforms. It is nearly all-weather capable and can easily be handled by a crane. On the other hand, frequencies of short waves measured in a fixed position are extremely frequency shifted by currents. This limits the usefulness of tower-based measurements, e.g., the short wave modulation by wind and waves or currents can only be estimated in a rough approximation. Consequently, a buoy was developed to reduce the frequency shifts. The principle of the buoy is to drift in the local surface current and to follow the amplitudes of long waves. Therefore, short waves are measured in facets of long waves and the Doppler shifts are minimized. The wind is measured at a constant height above the long wave profile and relative to the moving facets. The paper describes the conventional measuring device and points out the necessity of the drifting buoy system. Examples of wind and wave spectra are presented and short wave modulations by long waves are depicted, too. From these measurements, new insights in short wave behaviour have to be expected 相似文献
19.
自然海况下波浪特性的初步研究 总被引：2，自引：0，他引：2
赵栋梁 《中国海洋大学学报(自然科学版)》2002,32(6):853-858
通过分析大量的外海浮标观测资料 ,发现波龄和无因次波高之间存在非常好的相关性 ,自然海况下的波浪场满足 3/ 5指数律 ,其波龄可达到几十 ,远远超过风浪波龄的上限 1 .4,说明波浪组成波之间波 -波共振非线性相互作用是波浪内部结构的主要调节机制 ,使波高和周期之间具有很好的相关性。 相似文献
20.
This is a Part I of a paper of nonlinearities of wind waves in the deep open ocean. First, considerations are given in order to verify the theoretical expression for bound waves from observed data. We compare the contribution of bound waves and double Bragg scattering to the second-order scattering, and we show that the contribution of bound waves is larger, and that bound waves can be detected by measuring the Doppler spectra of HF (high-frequency) radio wave scattering from the sea surface. Moreover, if the theory of the HF radio wave scattering from the sea surface is verified, so is the second-order perturbation theory for bound waves. Then, the contributions of bound waves to ocean wave spectra are investigated on the basis of the nonlinear theory. The bound waves are shown to modify frequency spectra and wave directional distributions at higher frequencies, and it is shown that although the modifications of frequency spectra are smaller for a two-dimensional field case than for a one-dimensional field case, they are not negligible at higher frequencies. On the other hand, the modifications of wave directional distributions are shown to be significant at higher frequencies. These discussions become significant only when bound wave predictions are verified in the open ocean. Consequently, it is shown that nonlinearities of water waves are important in considering both radio wave scattering from the sea surface and the detailed structures of ocean wave spectra at high frequencies. 相似文献