ON DOPPLER-SPREADING MODELS OF INTERNAL WAVES

Present Doppler-spreading models for short internal waves in the atmos phere and the ocean either neglect the time dependence of the backgrou nd long-wave shear entirely, or ignore time-dependent effects in their parameterization of dissipation. We use ray and numerical simulations to examine the Doppler spreading of a short internal-wave packet by a n inertia-wave packet. The results are enough to show that time depend ence in the long-wave shear can make a significant difference to short -wave behavior, and will need to be taken into account in future model ling efforts.