摘要:

Barotropic instability of weakly non-parallel zonal flows with localized intense shear regions is investigated numerically. The numerical integrations of the linear stability problem reveal the existence of unstable localized wave packets whose spatial structure and eigenfrequencies depend on two parameters which measure the degree of supercriticality and the zonal length-scale of the shear region. The results indicate that the structure of the instability is determined by conditions that ensure the decay of the wave packet at infinity and the transition from long to short waves across a turning point (critical layer) region which is controlled by non-parallel effects. The controlling influence exerted by the weak non-parallel effects on the evolution of the instability underlines the weakness of the parallel flow assumption which can be used locally, away from critical layers, as a diagnostic tool only.

ISSN:0309-1929    

DOI:10.1080/03091928308210116

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

The problem of oblique incidence of internal ocean waves on a thin submerged ocean barrier is considered when the ocean has exponential density stratification. A Wiener-Hopf approach is used combined with numerical evaluation of series. Results for the reflected energy are obtained and reveal a complex dependence on incidence and barrier height. Application of this model to waves incident on the Mid-Atlantic ridge suggests that the ridge almosts isolates first mode energy on one side of the ocean from the other side. In certain circumstances there, is a surprising appearance of “barrier” waves. These waves are closely confined to the barrier and propagate along it.

ISSN:0309-1929    

DOI:10.1080/03091928308210117

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Part II of this series of papers provided those modes of the Non-Diffusive Zonal momentum Fluxes (NDZF) which reproduce the observed profiles for the angular velocity and horizontal Reynolds stress of the Sun. In explaining the fluxes we now consider the influence of the Coriolis force on given turbulence models. For solar applications we find that the basic rotation must be assumed to be neither too slow nor too rapid in order to allow a non-trivial expansion of the NDZF. Two different turbulence fields provide the desired latitudinal profiles but give different radial rotation laws: turbulence with a dominant horizontal (vertical) intensity always yields equatorial acceleration as well as the observed horizontal Reynolds stresses in connection with radial superrotation, ∂Ω/∂r>0 (subrotation, ∂Ω/∂r<0). In both cases the turbulent cells must be rather flat.

ISSN:0309-1929    

DOI:10.1080/03091928308210118

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor