摘要:

We consider the propagation of acoustic waves in an ocean sound channelC(z, x) with slow dependence onx. The travel timetRDin the range-dependent channel differs from the travel timetRAthrough the range-averaged sound channelCRA(z) = ±C(z, x)⟩x. The Hamiltonian formulation (Wunsch, in press) takes advan tage of the nearly periodic (inx) paths of the ray loops. The biastRD-tRAfor anadiabatic x-dependence is a function only of the variance in the channel parameters. Generally (but not always)tRD<tRA, thus giving a “warm bias” in the range-averaged ocean for any inversion of the acoustic travel times which ignores the range dependence of the sound channel. We derive bias formulae for three models ofx-dependence, corresponding to perturbations of the first and second baroclinic modes, respectively, and to anx-dependent surface warming.

ISSN:0309-1929    

DOI:10.1080/03091928708208803

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

In seeking to determine how the energy in a continental shelf wave that has travelled across the Great Australian Bight can reach the east Australian coast, the reflection/ transmission process at the southern tip of Tasmania is modelled by using a doublesided continental shelf of exponential/constant depth profile on which the coastline is semi-infinite.

ISSN:0309-1929    

DOI:10.1080/03091928708208804

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

A nonlinear energy stability analysis is presented for the penetrative convection model of Veronis (1963). The critical Rayleigh number boundary determined here ensures nonlinear stability for arbitrary sized initial amplitudes, unlike the conditional results of Straughan (1985).

ISSN:0309-1929    

DOI:10.1080/03091928708208805

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

Although the undular instabilities of a stratified horizontal magnetic field have been studied in a number of contexts we believe that the physical mechanism responsible for the instability has not been fully explained. In this paper we present a new explanation of why these instabilities occur, considering in detail the differing cases of two-dimensional and three-dimensional motions.

ISSN:0309-1929    

DOI:10.1080/03091928708208806

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

The magnetohydrodynamic stability of a class of magnetohydrostatic equilibria is investigated. The effect of gravity is included as well as the stabilising influence of the dense photospheric line-tying.

ISSN:0309-1929    

DOI:10.1080/03091928708208807

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

A quasi-linear approach to the problem of the evolution of a shear flow on the β-plane is considered for the case when a large number of waves with close phase velocities are excited. Their interaction with the flow occurs mainly in a narrow resonance region due to the presence of a positive derivative on the absolute vorticity profile Ωa(y).

ISSN:0309-1929    

DOI:10.1080/03091928708208808

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor