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1.
Transformation of internal tidal waves over the Guinean shelf is studied on the basis of theoretical and field research. This area is characterized by the presence of a narrow high-frequency waveguide. Internal tides propagating over the shelf are similar to shock waves. Short-period oscillations with an amplitude of 15 m develop at the wave's fore front. A shock wave is generated at the phase of a syzygial tide.Translated by V. Puchkin. 相似文献
2.
V. G. Bondur Yu. V. Grebenyuk K. D. Sabynin 《Izvestiya Atmospheric and Oceanic Physics》2009,45(5):598-607
Based on the results of analyzing the characteristics of currents and temperature measured in the water space of the Mamala
Bay (the Island of Oahu, Hawaii), we investigate the main properties of the field of short-period internal waves, which is
very complex. We focus on analyzing the spectral characteristics and orbit parameters for waves with a period of 20 minutes.
The results of investigations reveal two types of short-period internal waves for this area: intense and fast waves propagating
predominantly toward the ocean and weaker and slower waves propagating mainly toward the coast. Suppositions are made on how
these waves form: the strong and fast waves are likely to be caused by the decay of locally generated internal tides near
the shelf edge, while the weak and slow and very short waves seem to result from the specific interaction between the pycnocline
and strong tidal currents over a steep slope. 相似文献
3.
We study nonlinear three-wave interactions between edge waves propagating in the same direction over the shelf step. The conditions
of synchronism are determined and the coefficient of interaction is computed for the cases where the waves of the five lowest
modes participate in the interaction. The space-time dynamics is studied by analyzing, as an example, a single triad of edge
waves. The possibility of interaction of edge waves in the regions with actual topography is demonstrated.
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Translated from Morskoi Gidrofizicheskii Zhurnal, No. 3, pp. 3–19, May–June, 2008. 相似文献
4.
The nonlinear modulation of water wave groups is investigated and the interaction equations with induced flows are obtained. The analysis is performed up to the third order of the wave steepness a by treating it as a small parameter in the singular perturbation technique by means of the Krylov-Bogoliubov-Mitropolski method. The equation which governs the development of the wave envelope is found by a modification of the ordinary nonlinear Schroedinger equation for the case of uniform depth. The equations governing the behavior of the induced mean flow are examined by deriving the second order flow when the form of the modulated wave train is prescribed. The present theory can describe the mean flow caused by the radiation stress. Some applications containing the monochromatic wave instability are given to confirm the theoretical results.An outline of this paper was presented at The Ocean Surface Symposium (Sendai, 1984). 相似文献
5.
A. A. Slepyshev 《Izvestiya Atmospheric and Oceanic Physics》2016,52(3):301-308
Free internal waves are considered in a Boussinesq approximation in the situation when horizontal eddy viscosity and diffusion in a vertically inhomogeneous flow are taken into account. The dispersion relation and wave damping factor are found in a linear approximation. The Stokes drift velocity is determined in the second order of smallness based on the wave amplitude. It has been indicated that the Stokes drift velocity, transverse with respect to the wave propagation direction, differs from zero if the flow-rate transverse component depends on the vertical coordinate. Vertical momentum fluxes differ from zero and can be comparable with or exceed the corresponding turbulent fluxes if eddy viscosity and diffusion are taken into account. 相似文献
6.
V. F. Ivanov 《Physical Oceanography》2001,11(5):425-437
On the basis of a nonlinear model taking into account viscosity, density diffusion, and currents, we perform the numerical
analysis of propagation of perturbations formed in the abyssal part of the Black Sea as a result of the action of tangential
wind stresses or density flows in the form of a strip on the sea surface. It is shown that, in the course of time, in the
region of the bottom slope, these perturbations generate a train of waves in the sea, which causes oscillations of the fields
of density and currents. There are some differences between the generation of internal waves by the flows of density and the
wind. Unlike the wind action, in the presence of flows of density in the upper layer in the region of the strip, the initial
period of generation is characterized by the formation of intense perturbations without train structure.
Translated by Peter V. Malyshev and Dmitry V. Malyshev 相似文献
7.
8.
J.W. Lavelle E.T. Baker G.J. Massoth 《Deep Sea Research Part II: Topical Studies in Oceanography》1998,45(12):2619-2636
Total heat, salt, and other tracer masses released during a hydrothermal event are shown to be proportional to, but not necessarily equal to, volume integrals of resulting water column anomalies. Proportionality coefficients depend on anomaly definition, on background hydrographic and tracer profiles, on expansion coefficients of the equation of state at an appropriate pressure, and on tracer to heat anomaly ratios at the venting source. For Gorda Ridge event plumes, which are described in other papers of this issue, volume integrals of conventionally defined heat anomalies underestimate actual released heat by a factor of 2.4 if the discharge is not anomalously saline. Under certain combinations of hydrographic and source anomaly conditions, not unlike those found on the East Pacific Rise at 10°N, the apparent total heat released during an event can be deceivingly zero. This analysis also establishes a linear relationship between the ratio of tracer anomaly to heat anomaly at any point in the plume to the same ratio at the source. One consequence is that the ratio of anomalous 3He to heat in Gorda Ridge event plumes is approximately 2.4 larger in the water column than it is at the source. Results are independent of the entrainment process involved in event plume formation, and they are shown to hold true even for background hydrographic profiles that do not vary linearly with depth. 相似文献
9.
I. I. Pipko S. P. Pugach I. A. Repina O. V. Dudarev A. N. Charkin I. P. Semiletov 《Izvestiya Atmospheric and Oceanic Physics》2015,51(9):1088-1102
This article presents the results of long-term studies of the dynamics of carbonate parameters and air–sea carbon dioxide fluxes on the Chukchi Sea shelf during the summer. As a result of the interaction of physical and biological factors, the surface waters on the west of Chukchi Sea were undersaturated with carbon dioxide when compared with atmospheric air; the partial pressure of CO2 varied in the range from 134 to 359 μatm. The average value of CO2 flux in the Chukchi Sea per unit area varied in the range from–2.4 to–22.0 mmol /(m2 day), which is significantly higher than the average value of CO2 flux in the World Ocean. It has been estimated that the minimal mass of C absorbed by the surface of Chukchi Sea from the atmosphere during ice-free season is 13 × 1012 g; a great part of this carbon is transported to the deeper layers of sea and isolated from the atmosphere for a long period of time. The studies of the carbonate system of the Chukchi Sea, especially of its western part, will provide some new data on the fluxes of carbon dioxide in the Arctic Ocean and their changes. Our analysis can be used for an interpretation of the satellite assessment of CO2 fluxes and dissolved CO2 distribution in the upper layers of the ocean. 相似文献
10.
《Deep Sea Research Part I: Oceanographic Research Papers》2007,54(1):75-84
A perpetual salt fountain can draw up deep sea water without any artificial energy source. This is one of the ideal ways to draw up deep sea water for nutrient enhancement application. A perpetual salt fountain experiment was carried out in May 2004. The estimated average velocity of the upwelling after 48 h from the start of the experiment was about 7 mm/s, and it continued for about 3 days. The flow rate with a single pipe was estimated as approximately 45 m3/day. The amount of upwelled deep sea water by this single pipe seems too small to be of benefit, but we can easily increase the amount by deploying a number of pipes. 相似文献
11.
Yutaka Isoda 《Journal of Oceanography》1993,49(5):535-549
The higher mode predominance in the current velocity fields associated with wind-induced shelf waves in the nondispersive regime is studied with a special attention to the effect of the geographical boundary, e.g. wide strait or wide bank areas. The effect of such large topographic change is represented by wind forcing with a finite dimension near the geographical boundary. The time development processes of the wind-induced shelf waves is examined in the context of an initial-value problem, where a spatially finite wind stress is applied att=0. Various modes of shelf waves excited at the boundary start propagating simultaneously and develop monotonically within the forcing region. After the passage of such wave, the energy of wind is used to maintain the attained equilibrium condition, i.e. the steady shelf circulation. The current evolution of the lower mode is restricted to the earlier stage because of the large propagation speed. In contrast, the higher mode waves can travel slowly within the forcing region so that the kinetic energy is supplied from wind stress for a long time before the equilibrium condition is established. Consequently, the observation at the fixed point near the geographical boundary would show that the higher mode waves gradually dominate as time goes on, i.e. for the long-term forcing. 相似文献
12.
The generation of a magnetic field by surface waves in a sea of finite depth is considered. The effect of self-induction on
this process is analyzed and the conditions under which self-induction is of considerable importance are determined. The effects
that sea depth, wave period, and wave-propagation direction have on the value and direction of the magnetic field induced
are studied. 相似文献
13.
14.
本文利用实验室波浪水槽观测规则长波对风浪的影响。谱分析显示,较之纯风浪谱,除已被广泛关注的长波抑制风浪这一现象外,当长波波陡较小,且频率远离风浪峰频时,长波还使得风浪谱向低频移动。本文利用Longuet-HigginsStewart(1960)理论,并考虑到风浪破碎的约束,计算了规则长波的存在对风浪谱的影响,发现可以较好地解释这一现象。这一工作表明,当长波波陡小且频率远离风浪峰频时,长波对短波的二阶调制及其引起的破碎加强可能是长波影响风浪的主要机制。 相似文献
15.
Shenn-Yu Chao Ping-Tung Shaw Ming-Kuang Hsu Ying-Jang Yang 《Journal of Oceanography》2006,62(6):811-823
We have investigated the reflection and diffraction of first-mode and second-mode solitary waves by an island, using a three-dimensional
nonhydrostatic numerical model. The model domain consists of a circular island 15 km in diameter in an ocean 300 m deep. We
use prescribed density anomalies in an initially motionless ocean to produce highly energetic internal solitary waves; their
subsequent propagation is subject to island perturbations with and without the effect of earth’s rotation. In addition to
reflected waves, two wave branches pass around the island and reconnect behind it. Island perturbations to the first-mode
and second-mode waves are qualitatively similar, but the latter is more profound because of the longer contact time and, in
the presence of earth’s rotation, the scale compatibility between Rossby radius of the second baroclinic mode and the island
diameter. Without earth’s rotation, reflected and diffracted waves are symmetrical relative to the longitudinal axis passing
through the island center. With earth’s rotation, the current following the wave front veers to the right due to Coriolis
deflection. For a westward propagating incoming wave, the deflection favors northward wave propagation in the region between
the crossover point and the island, shifting the wave reconnection point behind the island northward. It also displaces the
most visible part of the reflected waves to the southeast. In the presence of earth’s rotation, a second-mode incoming wave
produces island-trapped internal Kelvin waves, which are visible after the passage of the wave front. 相似文献
16.
Koki Midorikawa 《Journal of Oceanography》1977,33(6):311-319
Internal waves were observed by measuring temperature variations of several subsurface layers at the innermost part of Suruga Bay from December 1968 to October 1971. Spectral energy densities of temperature fluctuations were computed from the records of the measurements. In the shorter period range from one minute to one hour, peaks of energy density were found occasionally in the range shorter than the minimum of VÄisÄlÄ periods computed from the vertical distribution of water density. It has been generally understood, however, that the periods of internal waves in a stable stratum should be within the range between the inertial and VÄisÄlÄ periods.The measurements of tidal currents in the surface and lower layers, which were undertaken simultaneously with the temperature measurements, revealed that the short-period oscillations were associated with the increase of current velocity and of vertical shear of current at the pycnocline.It is considered that observed periods shorter than the minimum of VÄisÄlÄ period are not real but apparent periods due to the Doppler effect, because the waves are generated in the velocity shear of tidal current and the source is moving towards the station with the tidal current. 相似文献
17.
Environmental data, particularly wave and current data, are of vital importance in offshore engineering. The needs for such data are discussed with reference to the influence of various environmental parameters on the loads of offshore structures. Data collected until now from the Norwegian continental shelf are reviewed. Furthermore, a planned data collection program is presented and discussed with respect to experience with instrumentation techniques, data recovery, and representativity, as well as interpretation and analysis gained from the present activity in this field. 相似文献
18.
Past studies of harbor resonance have mainly been restricted to the quasi-steady oscillations induced by steady wave conditions. This paper investigates the response of a rectangular harbor to subaerial landslide-generated impact waves based on physical models, in order to compare the oscillations induced by steady and transient waves. In response to steady incident waves, oscillations within the harbor need to experience a long process to obtain their maximum value before the input energy and the losses are balanced. Landslide-generated impact waves usually include components with solitary wave characteristics and also components with dispersive wave characteristics. Each component travels with a different celerity. Usually, solitary wave components propagate faster, and arrive in the harbor first. Oscillations attain their maximum status as soon as these components arrive. The subsequently arriving components with dispersive characteristics do not enhance the resonance oscillations. So the waves with solitary characteristics are considered to play an important role in harbor resonance. Numerical experiments, using the FUNWAVE model, were conducted in order to further verify these conclusions. 相似文献
19.
Takeshi Uji 《Journal of Oceanography》1978,34(5):189-203
In the framework of linear wave theory both the effects of tangential and normal stresses on the water waves are discussed without the assumption of irrotational water motion. A formal solution initially at rest with level surface and developed under the actions of the surface stresses depending arbitrarily on time and sinusoidally on space is obtained.A progressive wave type tangential stress whose wave number and frequency are satisfying the dispersion relation of the water waves is shown to be equivalent to the normal stress of the same type on the growth of the waves except the phase relations between the stresses and the water motion. The growth rate of the waves induced by the tangential stress is also shown to be quite insensitive to the actual value of the viscosity.The rotational part of the water motion can dominate only in the early stage of wave generation and becomes negligible with the growth of the waves relative to the irrotational part of the motion even in the case where the motion is induced by the tangential stress alone. Therefore it is not reasonable to neglect effect of the tangential stress on wind waves even if the developed wind waves seem to be irrotational. 相似文献
20.
A numerical model which consists of the Korteweg-de Vries (KdV) equation, the action balance equation and the radar backscat- tering model is developed to simulate the frequency dependence of synthetic aperture radar (SAR) remote sensing of nonlinear o- cean internal waves. Muhifrequency data collected by NASA SIR - C SAR and NASA JPL AIRSAR are used as comparison. Case studies show that the results of simulation agree well with the results of SAR data. 相似文献
