Extended Abstract (176K)7.4
Simulation of inertial instability in a primitive equations model
D. Pendlebury, NorthWest Research Associates, Bellevue, WA; and T. J. Dunkerton
Equatorial inertial instability simulated in middle atmosphere models is characterized by vertical gridscale structures in the zonal-mean winds and temperature. This paper will examine the three-dimensional structure of the instability. It will be shown that the instability has a zonal wavenumber dependence that is selected by the winter-hemispheric planetary waves impinging upon the zero-wind line. The breakdown of the unstable region will be examined, along with the effects on the zonal-mean state. Modification of the potential vorticity gradient on the summer side of the equator by inertial instability creates a region of barotropically unstable flow that leads subsequently to the excitation of two-day waves. It will be demonstrated that the inertial instability also generates small-scale travelling waves. Examination of the dispersion relation suggests that these are gravity waves.
Session 7, Stability of Flows
Tuesday, 10 June 2003, 11:30 AM-3:45 PM
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