2.3A
Spontaneous inertia-gravity wave radiation from cloudy and baroclinic cyclones
David A. Schecter, NorthWest Research Associates, Bellevue, WA; and M. T. Montgomery
We here present a system of equations that approximately govern small amplitude perturbations in a non-precipitating cloudy vortex. The cloud coverage can be partial or complete. The model is used to examine how clouds affect the spontaneous radiation of inertia-gravity waves from an atmospheric cyclone at high Rossby and Froude numbers (a parameter regime accessible to hurricanes and mesocyclones). The basic state of the cyclone is barotropic and has a potential vorticity distribution that decays monotonically with distance from the axis of symmetry. The radiation is produced by discrete, three-dimensional vortex Rossby waves, and has positive feedback on those waves. However, cloud coverage indirectly enhances the rates at which the Rossby-wave critical layers absorb wave activity. As a result, sufficiently dense cloud coverage damps the vortex Rossby waves and suppresses inertia-gravity wave radiation. In another development, the formal theory for this kind of spontaneous radiation is extended to baroclinic vortices with three-dimensional critical shells.
Session 2, Stability of Flows
Monday, 25 June 2007, 10:45 AM-12:15 PM, Ballroom South
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