摘要:

It is demonstrated in laboratory experiments with rotating shallow water that large scale Rossby vortices, greater than the Rossby-Obukhov radius in size, have dispersive and non-linear properties that are fundamentally different for the two possible polarities. We call this “cyclonic-anticyclonic asymmetry”. This asymmetry manifests itself in the following way: first, anticylones, unlike cyclones, do not undergo the dispersive spreading inherent in a linear wave packet. and therefore, having a considerably longer natural lifetime, are obvious candidates for Rossby solitons; second, dipolar vortices are, because of the comparatively rapid decay of a cyclone, transformed into anticyclonic solitons; third, anticyclones are much more readily generated by zonal flows of the type existing in planetary atmospheres. The evident dominance of anticyclones amongst the long-lived vortices in the atmospheres of giant planets strongly suggests that the cyclonic-anticyclonic symmetry plays a decisive role in the atmospheric cyclogenesis of large planets.

ISSN:0309-1929    

DOI:10.1080/03091929008219505

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

We demonstrate the existence of a class of dissipative, stratified, parallel shear flows which, as a consequence of linear supercritical instability, evolve directly into three-dimensional flows without the requirement for an intermediate two-dimensional finite-amplitude state. This represents a counter-example to a common misinterpretation of Squire's theorm, namely that the fastest-growing unstable mode of a dissipative parallel shear flow must be two-dimensional.

ISSN:0309-1929    

DOI:10.1080/03091929008219506

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

In recent years there has been rapidly growing interest in deterministic dynamo action: to what extent can non-random conducting flows sustain magnetic fields, and efficiently so, at the high magnetic Reynolds numbers which are common in the natural environment? For a dynamo to be relevant to astrophysical applications, it can be crucial that it be “fast” in the sense of Vainshtein and Zeldovich (1972): the exponential growth rate of the magnetic field should remain positive and bounded away from zero as the magnetic Reynolds number tends to infinity. Research in this area involves a mixture of advanced numerical simulations and analytical work which touches on delicate issues in the theory of dynamical systems. A workshop was held in the Observatoire de Nice, where recent advances, controversies and the possibilities for future collaboration were discussed in an informal atmosphere, reflected in this report. Note that to make the report more readable, references are not given for papers presented at the workshop itself.

ISSN:0309-1929    

DOI:10.1080/03091929008219507

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Atmospheric Tidal and Planetary Waves, by H Volland, Kluwer Academic Publishers, 1988, x+348 pp., US$99, (ISBN 90-277-2630-2)

ISSN:0309-1929    

DOI:10.1080/03091929008219508

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Wave Interactions and Fluid Flows by A. D. D. Craik, Cambridge University Press, 1985, xii+322 pp., $37.50, US$65 (ISBN 0-521-26740-4). Paperback version 1988, US$24.95.

ISSN:0309-1929    

DOI:10.1080/03091929008219509

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor