Baroclinic instability of quasi-geostrophic flows localized in a thin layer

• Published in: Journal of Fluid Mechanics
• Main Author: Benilov, ES
• Format: Article in Journal/Newspaper
• Language: English
• Published: Cambridge Univ Press 1995
• Subjects: Earth Sciences; Oceanography; Physical Oceanography; Pacific; Subarctic
• Online Access: https://doi.org/10.1017/S002211209500111X; http://ecite.utas.edu.au/3520

This paper examines the baroclinic instability of a quasi-geostrophic flow with vertical shear in a continuously stratified fluid. The flow and density stratification are both localized in a thin upper layer. (i) Disturbances whose wavelength is much smaller than the deformation radius (based on the depth of the upper layer) are demonstrated to satisfy an equivalent two-layer model with properly chosen parameters. (ii) For disturbances whose wavelength is of the order of, or greater than, the deformation radius we derive a sufficient stability criterion. The above analysis is applied to the subtropical and subarctic frontal currents in the Northern Pacific. The effective time of growth of disturbances (i) is found to be 1622 days, the characteristic spatial scale is 130150 km. 1995, Cambridge University Press. All rights reserved.