Abstract
The technique of slow and fast variables is used to investigate the relation between the amplitude of hydromagnetic-planetary-gravity waves and the strength of the basic state zonal flow and zonal magnetic field.
It is found that the amplitude of pure, vertically propagating planetary (Rossby)-gravity waves increases as the zonal flow strength increases, but not in a simple linear manner, for all phase speeds.
For hydromagnetic-planetary-gravity waves the wind shear has the same destabilising effect on the wave amplitude, whereas, in contrast, the magnetic field has a stabilising effect in the sense that the wave amplitude decreases as the magnetic field intensity increases.
Résumé
On a utilisé la méthode des variables lentes et rapides pour rechercher une relation entre l'amplitude des ondes hydromagnètiques planétaires de gravité et l'intensité du flux de base zonal et du champ magnétique zonal.
On a découvert que l'amplitude d'ondes pures planétaires (Rossby) de gravité se propageant verticalement augmente en même temps que le flux zonal pour toutes les vitesses de phase, mais non de manière simplement linéaire.
Pour les ondes hydromagnétiques planétaires de gravité le cisaillement pour le vent magnétique a un effet similaire déstabilisateur sur l'amplitude de l'onde, alors que, au contraire, le champ magnétique a un effet stabilisateur, c'est-à-dire que l'amplitude de l'onde décroît quand l'intensité du champ magnétique augmente.
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Mekki, O.M.E. Internal hydromagnetic planetary-gravity waves in zonal wind-magnetic shears. Two-variables technique. Z. angew. Math. Phys. 33, 461–472 (1982). https://doi.org/10.1007/BF00955696
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DOI: https://doi.org/10.1007/BF00955696