Normal‐mode surface waves in the pseudobranch on the (001) plane of gallium arsenide

1976 ◽  
Vol 47 (4) ◽  
pp. 1712-1713 ◽  
Author(s):  
G. I. Stegeman
Keyword(s):  
Gallium Arsenide ◽  
Surface Waves ◽  
Normal Mode

MHD surface waves in high- and low-beta plasmas. Part 1. Normal-mode solutions

1989 ◽  
Vol 42 (1) ◽  
pp. 75-89 ◽  
Author(s):  
Z. E. Musielak ◽  
S. T. Suess
Keyword(s):  
Magnetic Field ◽  
Surface Waves ◽  
Normal Mode ◽  
General Structure ◽  
Normal Modes ◽  
Resonant Absorption ◽  
Normal Surface ◽  
Phase Mixing ◽  
Cold Plasmas ◽  
The Waves

Since the first paper by Barston (1964) on electrostatic oscillations in inhomogeneous cold plasmas, it has been commonly accepted that all finite layers with a continuous profile in pressure, density and magnetic field cannot support normal surface waves but instead the waves always decay through phase mixing (also called resonant absorption). Here we reanalyse the problem by studying a compressible current sheet of a general structure with rotation of the magnetic field included. We find that all inhomogeneous layers considered in the high-β plasma limit do not support normal modes. However, in the limit of a low-β plasma there are some cases when normal-mode solutions are recovered. The latter means that the process of resonant absorption is not common for all inhomogeneous layers.

The deformation of steep surface waves on water ll. Growth of normal-mode instabilities

1978 ◽  
Vol 364 (1716) ◽  
pp. 1-28 ◽  
Keyword(s):  
Surface Waves ◽  
Normal Mode ◽  
Gravity Waves ◽  
Wave Breaking ◽  
Wave Train ◽  
Local Instability ◽  
Fast Growing ◽  
Intermediate Range ◽  
Time Stepping ◽  
Rates Of Growth

Studies of the normal-mode perturbations of steep gravity waves (Longuet-Higgins 1978 b , c ) have suggested two distinct types of instability: at low wave steepnesses we find subharmonic instabilities with fairly low rates of growth, and at higher wave steepnesses there are apparently local (‘superharmonic’) instabilities leading directly to wave breaking. Between these two types of instability is an intermediate range of wave steepnesses where the unperturbed wave train is neutrally stable. In the present paper we employ the time-stepping method of an earlier paper (Longuet-Higgins & Cokelet 1976) to test the rate of growth of each type of instability. For the initial linear stages of each instability, the computed rates of growth are accurately confirmed, and it is verified that the local instability does indeed lead to breaking. The later nonlinear stages of the subharmonic instabilities are further investigated. In the two examples so far computed it is found that the gradual rates of growth of the subharmonic instabilities are maintained, and that ultimately every alternate crest develops a fast-growing local instability which quickly leads to breaking.

scholarly journals Local Coupling and Conversion of Surface Waves due to Earth’s Rotation. Part 2: Numerical Examples

2020 ◽  
Author(s):  
Christoph Sens-Schönfelder ◽  
Ebru Bozdağ ◽  
Roel Snieder
Keyword(s):  
Surface Wave ◽  
Surface Waves ◽  
Normal Mode ◽  
Coriolis Force ◽  
Rayleigh Waves ◽  
Love Wave ◽  
Resonant Coupling ◽  
Phase Velocities ◽  
Rayleigh And Love Waves ◽  
Similar Phase

Summary Rotation of the Earth affects the propagation of seismic waves. The global coupling of spheroidal and toroidal modes by the Coriolis force over time is described by normal-mode theory. The local action of the Coriolis force on the propagation of surface waves can be described by coefficients for the coupling between propagating Rayleigh and Love waves as derived by (Landau & Lifshitz 1959). Using global wavefield simulations we show how the Coriolis force leads to coupling and conversion between both surface wave types depending on latitude, propagation direction, frequency, and local velocity structure. Surface wave coupling is most efficient for periods where the modes have similar phase velocities, a condition that is equivalent to the selection rules of the angular degree in the normal-mode framework, a phenomenon that we refer to as resonant coupling. In the time-domain, resonant coupling gradually converts energy from one wave type–Rayleigh waves or Love wave–into the other, which then propagates independently. Due to the lateral heterogeneity, the condition of equal phase velocity renders the rotational coupling location-dependent. East-west oriented ray path segments and segments at high latitudes (across the Poles) only weakly couple the fundamental mode Rayleigh and Love waves while coupling is strongest for propagation along the meridians across the equator. At 250 s period, where Love and Rayleigh waves have similar phase velocities, the net energy transfer from Rayleigh to Love wave reaches about 10% for one orbit.

scholarly journals P and S tomography using normal-mode and surface waves data with a neighbourhood algorithm

2002 ◽  
Vol 149 (3) ◽  
pp. 646-658 ◽  
Author(s):  
Caroline Beghein ◽  
Joseph S. Resovsky ◽  
Jeannot Trampert
Keyword(s):  
Surface Waves ◽  
Normal Mode ◽  
Neighbourhood Algorithm
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