Internal wave

About: Internal wave is a research topic. Over the lifetime, 8311 publications have been published within this topic receiving 221331 citations. The topic is also known as: Internal_wave.

Introduction to Geophysical Fluid Dynamics

Abstract: Preface. I. FUNDAMENTALS. 1. Introduction. 2. The Coriolis Force. 3. The Governing Equations. II. ROTATION EFFECTS. 4. Geostrophic Flows and Vorticity Dynamics. 5. The Ekman Layer. 6. Linear Barotropic Waves. 7. Barotropic Instability. 8. Large-Scale Ocean Circulation. III. STRATIFICATION EFFECTS. 9. Stratification. 10. Internal Waves. 11. Turbulence in Stratified Fluids. IV. COMBINED ROTATION AND STRATIFICATION EFFECTS. 12. Layered Models. 13. Stratified Geostrophic Dynamics. 14. Upwelling. 15. Quasi-Geostrophic Dynamics. 16. Barolinic Instability. 17. Fronts, Jets, and Vortices. V. SPECIAL TOPICS. 18. Climate Dynamics. 19. Equatorial Dynamics. Appendix: Wave Kinematics. References. Index.

Turbulence and mixing in a Scottish Loch

Abstract: It is nearly three-quarters of a century since E. R. Watson (1904) and E. M. Wedderburn (1907) made the observations in Loch Ness which showed conclusively, and for the first time, that large bodies of water contain beneath their surface the wave motions which have now come to be known as internal waves. The observations and theory of these waves have developed much since those days, but the Loch is still very useful as a site in which to observe and examine phenomena which are also found in other bodies of water, particularly the ocean. In particular the Loch provides a large-scale natural ‘laboratory’ in which a variety of small-scale phenomena associated with turbulence in a stratified fluid may be studied. Observations have been made with a novel profiling instrument which measures the horizontal velocity of the water and its temperature, from which the density may be inferred. These observations serve to illustrate a variety of local conditions which occur in calm weather, as the Loch responds to the wind and during the passage of an internal surge. Analysis of the records is conducted in terms of an intermittency index (the fraction of fluid in which the density decreases with depth), the Richardson number and a length scale which characterizes the vertical scale of the regions which are found to be unstably stratified. Semi-empirical formulae for the eddy diffusion coefficient and the rate of dissipation of kinetic energy in the turbulent motion are examined to see whether they are consistent with observations. No universal value of the Richardson number is found, but this may be a consequence of the rather low values of Reynolds number found in the Loch thermocline.

Oceanic Rogue Waves

Abstract: Oceanic rogue waves are surface gravity waves whose wave heights are much larger than expected for the sea state. The common operational definition requires them to be at least twice as large as the significant wave height. In most circumstances, the properties of rogue waves and their probability of occurrence appear to be consistent with second-order random-wave theory. There are exceptions, although it is unclear whether these represent measurement errors or statistical flukes, or are caused by physical mechanisms not covered by the model. A clear deviation from second-order theory occurs in numerical simulations and wave-tank experiments, in which a higher frequency of occurrence of rogue waves is found in long-crested waves owing to a nonlinear instability.

Space Charge Waves in Cylindrical Plasma Columns

Abstract: When a plasma is of finite transverse cross section, space-charge waves may propagate even in the absence of a drift motion or thermal velocities of the plasma. Some of the properties of these space charge waves have been investigated by regarding the plasma as a dielectric and solving the resulting field equations. The effect of a steady axial magnetic field is considered, but motion of heavy ions and electron temperature effects are neglected. Waves are found to exist at frequencies low compared with the plasma frequency as well as waves with oppositely directed phase and group velocities (backward waves).Many of the features of these waves have been verified experimentally by measuring phase velocity and attenuation of waves along the positive column of a low pressure mercury arc in an axial magnetic field. Measurements of electron density have been made using these waves and the results are compared with those obtained by other methods. An interesting feature of these measurements, of value in plasma diagnostics, is that they can be made with frequencies which are small compared with the plasma frequency.

Algebraic Solitary Waves in Stratified Fluids

Abstract: By using nonlinear perturbation method a time-dependent equation is derived which governs internal waves in stratified fluids of great depth. The resultant equation takes the following form :