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Abstract
The generation and propagation of a packet of smallamplitude inertiagravity waves (IGWs) in a rotating stratified balanced flow Is described. The initially balanced geophysical flow is an unstable baroclinic jet which breaks LIP into a street of cyclonic and anticyclonic vortices. The smallamplitude unbalanced component of the flow is extracted from the largeamplitude mesoscale balanced flow using the optimal potential vorticity balance approach. This analysis reveals that during the instability the balanced flow spontaneously emits bursts of IGWs. The emission occurs along two directions, into and Out of the anticyclonic vortices. The inwardwaves remain trapped inside the vortices while the outwardwaves propagate away from them as a packet of smallamplitude IGWs with a threedimensional helical structure. The wave packet emission is confirmed for different spatial resolutions (128(3), 160(3), 192(3) and 256(3) grid points). The ratio between the balanced vertical and horizontal velocity components is of the order of 10(3), as is typical of mesoscale geophysical flows. The ratio between the unbalanced vertical and horizontal components is about 0.1. Since the unbalanced horizontal and the balanced vertical velocity components are of similar magnitude, the vertical velocity of the IGWs is about 10(4) times the balanced horizontal velocity. The IGWs are dominated by frequencies close to the inertial frequency and have a clockwise rotating horizontal velocity, similar to plane wave Solutions.
Original language  English 

Pages (fromto)  107117 
Number of pages  11 
Journal  Journal of Fluid Mechanics 
Volume  553 
DOIs  
Publication status  Published  25 Apr 2006 
Keywords
 LORENZKRISHNAMURTHY MODEL
 POTENTIAL VORTICITY
 SLOW QUASIMANIFOLD
 VERTICAL VELOCITY
 MANIFOLD
 DYNAMICS
 MOTION
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Dive into the research topics of 'Spontaneous generation of inertiagravity wave packets by balanced geophysical flows'. Together they form a unique fingerprint.Projects
 1 Finished

EPSRC GR/S69290/01: A new twist to rotating stratified turbulance
1/03/04 → 28/02/07
Project: Standard