Generation and Structure of Solitary Rossby Vortices in Rotating Fluids.
Abstract
The formation of zonal flows and vortices in the generalized Charney-Hasegawa-Mima equation is considered. We focus on the regime when the size of structures is comparable to or larger than the deformation (Rossby) radius. In this case an additional nonlinearity, physically analogous to the scalar nonlinearity of the Korteweg-de Vries equation which describes solitons, should be taken into account footnote V.I. Petviashvili, Sov. Phys. JETP Lett. 32, 619 (1980). The combined impact of the β-effect (both Rossby waves and KdV nonlinearity) and deformation radius on coherent structures is studied. It is shown that for parameters close to those of giant planets large-scale zonal flows created by small-scale forcing tend to preferentially form anticyclonic vortices. Their emergence can be explained by the modified Rayleigh-Kuo instability criterion which takes into account the deformation of free surface. We have provided numerical evidence that for scales larger than the Rossby radius, the scalar nonlinearity is responsible for the formation of ring anticyclonic vortices with quiescent cores consistent with observations of the Jovian and oceanic flows. Physical mechanisms that lead to these phenomena and their relevance to turbulence in planetary atmospheres are discussed.
- Publication:
-
APS Division of Fluid Dynamics Meeting Abstracts
- Pub Date:
- November 1996
- Bibcode:
- 1996APS..DFD..FM10K