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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.
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
3.
A. V. Babanin P. P. Verkeev B. B. Krivinsky V. G. Proshchenko 《Physical Oceanography》1993,4(5):399-407
An accelerometer buoy wave gauge developed in the Marine Hydrophysical Institute of the Ukrainian Academy of Sciences is described. This allows measurement of acceleration and the sea surface elevation in the system of reference connected with a buoy. The integral and frequency spectral characteristics of waves can be computed from the records of the wave gauge signal. The use of a buoy accelerometer at sea provides a possibility to derive effective information on the wind waves.Translated by Mikhail M. Trufanov. 相似文献
4.
In most design applications such as alignment of the berthing structure and breakwater alignment, it becomes necessary to determine the direction of design wave. There are two different approaches to determine wave direction. One involves the use of first order Fourier coefficients (mean wave direction) while the other uses second order Fourier coefficients (principal wave direction). Both the average wave direction over the entire frequency range (0.03–0.58 Hz) and the direction corresponding to the peak frequency are used in practice. In the present study, comparison is made on wave directions estimated based on first and second order Fourier coefficients using data collected at four locations in the west and east coasts of India. Study shows that at all locations, the mean and principal wave directions for frequencies ranging from 0.07 to 0.25 Hz (±0.5 times peak frequency) co-vary with a correlation coefficient of 0.99 but at lower and higher frequencies, difference between the parameters is large. Average difference between the mean wave direction at peak frequency and the average over the frequency related to spectral energy more than 20% of maximum value is less, around 13°. Study shows that average difference in the sea and swell directions is around 39°. 相似文献
5.
海底峡谷在全球陆缘广泛分布,是浅海沉积物向深海运移的主要通道,对于理解深海浊流触发机制、深海沉积物的搬运模式、深海扇的发育历史和深海油气资源勘探等均具有重要意义。本文基于高分辨率高精度的多波束测深数据,首次对南海东北部海底峡谷体系进行了研究,精细刻画了高屏海底峡谷、澎湖海底峡谷、台湾浅滩南海底峡谷和东沙海底峡谷等4条大型海底峡谷的地貌特征并分析其发育控制因素。海底坡度、构造运动、海山与海丘是影响南海东北部峡谷群走向与特征的重要因素,其中,海底坡度对于峡谷上游多分支与“V”字特征有显著的控制作用;构造运动是控制高屏海底峡谷走向的因素,澎湖海底峡谷的走向则与菲律宾海板块与欧亚板块碰撞有关,东沙海底峡谷的走向则与东沙运动相关,台湾浅滩南海底峡谷上段受NW向断裂构造的控制;海山的阻挡作用造成峡谷局部走向和特征改变。海底峡谷群输送大量陆源沉积物到深海盆并形成大面积的沉积物波,海山和沉积物波的发育导致东沙海底峡谷下段“回春”和转向。 相似文献
6.
Analysis of freak wave measurements in the Sea of Japan 总被引：3，自引：0，他引：3
This paper presents an analysis of a set of available freak wave measurements gathered from several periods of continuous wave recordings made in the Sea of Japan during 1986–1990 by the Ship Research Institute of Japan. The analysis provides an ideal opportunity to catch a glimpse of the statistics of freak waves in the ocean. The results show that a well-defined freak wave may occur in the developed wind–wave condition: S(f)∝f−4, with single-peak directional spectra. The crest and trough amplitude distributions of the observed sea waves including freak waves are different from the Rayleigh distribution, although the wave height distribution tends to agree with the Rayleigh distribution. Freak waves can be readily identified from the wavelet spectrum where a strong energy density occurs in the spectrum, and is instantly surged and seemingly carried over to the high-frequency components at the instant the freak wave occurs. 相似文献
7.
Lipa B.J. Barrick D.E. Isaacson J. Lilleboe P.M. 《Oceanic Engineering, IEEE Journal of》1990,15(2):119-125
CODAR, a high-frequency (HF) compact radar system, was operated continuously over several weeks aboard the semisubmersible oil platform Treasure Saga for the purpose of wave-height directional measurement and comparison. During North Sea winter storm conditions, the system operated at two different frequencies, depending on the sea state. Wave data are extracted from the second-order backscatter Doppler spectrum produced by nonlinearities in the hydrodynamic wave/wave and electromagnetic wave/scatter interactions. Because the floating oil rig itself moves in response to long waves, a technique has been developed and successfully demonstrated to eliminate to second order the resulting phase-modulation contamination of the echo, using separate accelerometer measurement of the platform's lateral motions. CODAR wave height, mean direction, and period are compared with data from a Norwegian directional wave buoy; in storm seas with wave heights that exceeded 9 m, the two height measurements agreed to within 20 cm RMS, and the mean direction to better than 15° RMS 相似文献
8.
Ambient noise in the surf zone, in the frequency range 120 Hz to 5 kHz, was recorded using a broad-band hydrophone, located approximately 1 m above bottom and 1-2 m below the mean sea surface. The predominant source of this noise is breaking waves. Analysis of simultaneous land-based video observations of the sea surface in the region of the hydrophone, along with wave height data, reveals quantitative correlation between wave-breaking events and the hydrophone signal. In energetic surf, locally breaking waves appear as discrete events in the ambient noise spectra. Distant breaking events do not appear to be detected, as distinct events above the ambient background noise, by the hydrophone. The noise events associated with local breakers are characterized by an asymmetry in the time envelope: low frequencies (less than 500 Hz) are observed leading the breaking crest, followed by a broader range of frequencies peaking in intensity with the passage of the wave crest above the hydrophone, and then decreasing abruptly at all frequencies. Low frequencies are generally not observed trailing the breaking wave. The detection by the hydrophone of breaking waves in the immediate vicinity implies that ambient noise in heavy surf provides a means of studying breaking-wave statistics in the surf zone in situ: in particular, the frequency of occurrence of local breaking 相似文献
9.
This paper provides an approach by which the scour depth below pipelines in shoaling conditions beneath non-breaking and breaking random waves can be derived. Here the scour depth formula in shoaling conditions for regular non-breaking and breaking waves with normal incidence to the pipeline presented by Cevik and Yüksel [Cevik, E. and Yüksel, Y., (1999). Scour under submarine pipelines in waves in shoaling conditions. ASCE J. Waterw., Port, Coast. Ocean Eng., 125 (1), 9–19.] combined with the wave height distribution including shoaling and breaking waves presented by Mendez et al. [Mendez, F.J., Losada, I.J. and Medina, R., (2004). Transformation model of wave height distribution on planar beaches. Coast. Eng. 50 (3), 97–115.] are used. Moreover, the approach is based on describing the wave motion as a stationary Gaussian narrow-band random process. An example of calculation is also presented. 相似文献
10.
作者利用浅地层剖面资料研究了天津近海海域存在的主要海底地质灾害。研究发现:浅层气、埋藏三角洲前缘、水下潮流沙脊、陡坎、沙波等地质灾害发育。浅层气主要分布在研究区北部海域的近岸附近,南部海域远离海岸浅层气逐渐增多;埋藏三角洲前缘分布区北至涧河口,南至南港工业区东部海域;水下沙脊分布于北部海域5 m~7 m水深的近岸带,地层内部前积斜层理发育;沙波区延伸长度约3 km,整体上在天津海域分布较少;海底表层陡坎出现在天津港及以南海域,其成因主要是航道两侧边缘陡坎或因吹填而抽走的泥沙造成的,近岸及远海地区均有分布。 相似文献
11.
12.
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
13.
Submarine channel levee systems form important hydrocarbon reservoirs in many deep marine settings and are often deposited within a structurally active setting. This study focuses on recent submarine channels that developed within a deepwater fold and thrust belt setting from the Levant Basin, eastern Mediterranean Sea. Compressional deformation within the study area is driven by the up-dip collapse of the Nile cone above the ductile Messinian Evaporites. Structures such as folds and strike slip faults exert a strong control on channel location and development over time. From this study four end-member submarine channel–structure interactions can be defined: Confinement, diversion, deflection and blocking. Each of these channel–structure interactions results in a distinct submarine channel morphology and pattern of development compared to unconfined channel levee systems. Each interaction can also be used to assess timing relationships between submarine channel development and deformation. 相似文献
14.
C. M. Alexander 《Ocean Engineering》1981,8(4):379-406
A cylinder in cross-flow experiences periodic forcing related to the shedding of vortices in its wake. Long wires in the ocean vibrate in response to this forcing, but their length and damping is such that boundary conditions do not generally apply to solutions of the equations of motion and their vibratory behavior at one point is of little consequence at remote points. The bulk of previous studies of vibrating wire characteristics have utilized only short wires or cylinders in the laboratory, so have not considered or even permitted this phenomenon.During a typical deployment of the Scripps Deep-Tow survey system to 2800 m a small 2-axis accelerometer package was attached to the tow wire at a depth of 30 m and its output recorded in a diver-operated vehicle about 1 m downstream. Analysis of this data produced sharply peaked spectra with the frequencies of vibration in the direction of flow twice those across the flow. Good correlations were found between mean amplitudes across the flow and the corresponding peak frequencies, and between mean amplitudes across and aligned with the flow. Preference for a specific phase relation between motions in the two planes suggests that vortex shedding occurs progressively and forcing has the form of a complex wave travelling down the wire.To investigate the implications of the preceding, a tow-tank fixture was built which permitted reproduction of amplitude, frequency and phase relations in a cylinder representing a point on the wire. A series of runs were then made to measure drag force directly and obtain an empirical drag law. A constant drag coefficient of 1.8 was found in the Reynolds number range 7000–12000, contrary to other investigations that have ignored vibrations in the flow direction. 相似文献
15.
The paper provides a bivariate distribution of wave power and wave height, as well as a bivariate distribution of wave power and wave period; both bivariate distributions are for individual waves within a sea state. This is relevant for e.g. making assessments of wave power devices and their potential for converting energy from waves. The results can be applied to compare systematically the wave power potential for individual waves in a given sea state at different locations. 相似文献
16.
T. Bjarte-Larsson 《Ocean Engineering》2006,33(7):847-877
A heaving axisymmetric floating body is tested with sinusoidal incident waves in a wave channel. It is connected to the piston of a pump, and it may be latched by an electromagnetic mechanism. Experimental results are compared with a linear mathematical model, for heave response, hydrodynamic parameters, absorbed wave power and converted hydraulic power. Heave resonance occurs at 1.1 Hz. For sub-resonant frequencies, latching control results in a significant increase in heave response and in absorbed, as well as converted, power. Hydraulic energy capture increases by a factor of 2.8 or 4.3 for frequency 0.75 or 0.5 Hz, respectively. 相似文献
17.
Robert H. Stewart 《Ocean Engineering》1977,4(2):101-107
Described herein is a self-contained, discus-hulled buoy 1.5 m dia., weighing 150 kg, which uses inertial instruments to measure wave height and tilt. Wave tank calibration and the theory of shallow draft buoys demonstrate such a hull accurately follows waves with length greater than twice the buoy diameter. The non-linear response of the buoy determines its sensitivity to low-frequency waves in a sea. And the ratio of wave signal to instrument “noise” is constant over the energetic part of the ocean-wave spectrum for measurements of wave acceleration and slope. 相似文献
18.
Interannual Variations of Sea Level at the Nansei Islands and Volume Transport of the Kuroshio Due to Wind Changes 总被引：4，自引：0，他引：4
Masaki Kawabe 《Journal of Oceanography》2001,57(2):189-205
Interannual variations of sea level at the Nansei Islands and volume transport of the Kuroshio during 1967–95 are calculated by integrating variations carried by windforced Rossby waves. Effects of eddy dissipation and ocean ridges are considered. Ridge effect is inferred by comparing between the calculated and observed sea levels. The calculation is satisfactory to sea levels and Kuroshio transport for the whole period. They are mostly caused by Rossby waves forced by wind and modified by the ridges, and are due to barotropic wave primarily and the first baroclinic wave secondly. The calculated Kuroshio transport well represents variations of several-year scales with maximums in respective duration of the large meander (LM) of the Kuroshio, as well as bi-decadal variation that transport was small during the non-LM period of 1967–75 and large during the LM-dominant period of 1975–91. Mean volume transport of the subtropical gyre is estimated at 57 Sv (1 Sv = 106 m3s–1) and divided by the Nansei Shoto Ridge into those of the Kuroshio in the East China Sea (25.5 Sv) and a subsurface current east of this ridge (31.5 Sv). The Subtropical Countercurrent and a southward deep current east of the Izu-Ogasawara Ridge are estimated at 16 Sv and 7 Sv, respectively. The calculated transports of the Kuroshio and other subtropical currents reach maximums at every El Niño event due to strong excitement of upwelling barotropic Rossby wave. 相似文献
19.
R. S. Bortkovskii 《Izvestiya Atmospheric and Oceanic Physics》2012,48(2):193-199
The results of hourly measurements of sea roughness and hydrometeorological parameters, which were automatically taken from
special buoys over a long period of time, were used. These buoys were located in the open regions of both the Atlantic and
Pacific oceans in different climatic zones; the mean water-surface temperature around the buoys varies from 1–3°C to 26–28°C.
In addition to measurement results, the tables contain data on the spectral density of sea roughness for a wide range of frequencies.
An analysis of these data, which was made for a short-wave region of the wind-wave spectrum, for the first time revealed a
noticeable watertemperature dependence of the spectral density of wind waves within the frequency range 0.30–0.40 Hz, which
corresponds to wave lengths of 9-4 m. The presence of such dependence is explained by a rapid temperature change in kinematic
sea-water viscosity. Earlier, we indicated the temperature dependence of only very short spectral components that relate to
a centimetric wavelength range. The statistical significance of the watertemperature effect on the spectral density of waves
of the indicated frequency is supported by the results of a variance analysis. Temperature variations in the parameter of
sea-surface roughness, which is determined, first of all, by the energy of the spectral shortwave region, are estimated. Altimetry
is the basic method which is used in remotely determining the velocity of near-water wind. This method allows one to obtain
records of deviations of the sea surface from the geoid surface and to calculate (on the basis of these records) the spectral
density of wave components of almost any frequency. It is known that the wave-spectrum components in the region of low frequencies
are almost always affected by ripple. Consequently, the energy of these components is determined not only by wind forcing,
and only the components in the range of frequencies exceeding approximately 0.3 Hz are purely windy. Therefore, using the
results of sea-surface altimetry in order to determine the velocity of near-water wind, one should use the spectral densities
of wave components in this frequency region. The water-temperature dependence of the spectral density of short wind waves
is manifested only in a certain frequency interval, which supports this recommendation. 相似文献
20.
Submarine pipelines are widely used coastal structures, and scour around them can influence their stability. In this study, scour around rigid submarine pipelines under normal-incidence irregular wave attack on horizontal and (1/10) sloping beaches is studied. This paper presents experimental results concerning scour under irregular wave attack. Multiple regression analysis is used to develop models to predict the scour depth under pipelines under the influence of irregular wave attack. The representative wave parameters that characterize the irregular sea state that causes the same scour depth as regular wave attack were determined. 相似文献