A critical layer dominated by nonparallel effects in a rotating barotropic flow
Abstract
The critical layer of perturbations to slowly modulating strong rectified currents induced by vorticity sources in a quasigeostrophic barotrophic flow is investigated. For r much greater than Re to the 3/2 and r much greater than delta squared, which correspond to realistic geophysical conditions, the critical layer is dominated by the advection of the perturbation's vorticity by the weak transverse velocity of the basic state and not by the traditional viscous or nonlinear balance. The Ekman, Rossby and Reynolds numbers of the flow are E, Ro and Re respectively and r = (sq rt E)/Ro, while delta is the parameter of nonlinearity. The width of the critical layer is O(r to the 1/6), which can be quite thick for relevant flow conditions. This suggests that nonparallel effects play an important role in the dynamics of large scale geophysical flows.
 Publication:

Proceedings of the Royal Society of London Series A
 Pub Date:
 August 1983
 DOI:
 10.1098/rspa.1983.0084
 Bibcode:
 1983RSPSA.388..293M
 Keywords:

 Barotropic Flow;
 Flow Stability;
 Vortices;
 Parallel Flow;
 Rossby Regimes;
 Stream Functions (Fluids);
 WentzelKramerBrillouin Method;
 Fluid Mechanics and Heat Transfer